Scientific publications—2014

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Each year, CRC's researchers author a number of publications communicating successes in advanced wireless telecommunications R&D. Integral to their work is sharing the results with others.

Here you will find abstracts and links to papers published in peer-reviewed scientific journals or books or presented at conference proceedings.

If you experience issues accessing the full report or the website, please contact us. Other formats of documents are also available upon request.


Research publications—2014
Title Authors
Dual-band SRR using CRLH TL-based elements

Year: 2014

Abstract: In this paper, a new dual-band split ring resonator based on composite right-/left-handed transmission line-based elements is proposed. The distributed elements within the resonator are patterned in the centre strip of a folded coplanar waveguide transmission line. The new elements which are deployed in a prototype transmission line-based inclusion provide a dual-band resonance behavior. The design procedure and theory behind the new inclusion are introduced. Simulated results agree well with the theoretical results. © 2014 IEEE.

Source title: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest)

DOI: 10.1109/APS.2014.6904503

Link: Dual-band SRR using CRLH TL-based elements

Abu Safia, O.; Talbi, L.; Hettak, K.
Versatile 20 GHz wideband RF digitizer for test and measurement

Year: 2014

Abstract: Wireless device manufacturers are challenged with the test and measurement of ever-evolving complex signals while at the same time contending with shrinking test equipment budgets. For example, modern wireless signals can have bandwidths up to 80 MHz [1] and can vary in operating frequency and amplitude over time. In contrast, affordable spectrum analyzers typically have narrow (up to 10 MHz) instantaneous bandwidth (IBW). This makes analyzing a time-varying wideband signal that is greater than 10 MHz in bandwidth with such narrowband instrumentation require a sweep over several frequency bands. This can yield erroneous measurement results. © 2014 IEEE.

Source title: IEEE Instrumentation and Measurement Magazine

Series Number: Volume 17 Issue 4

DOI: 10.1109/MIM.2014.6873723

Link: Versatile 20 GHz wideband RF digitizer for test and measurement

Adnani, N.; Lamanque, M.; Helaly, T.; Farhan, M.; Hember, T.; Ward, I.
Adaptive topology control to improve network performance through power and rate adaptation

Year: 2014

Abstract: Adaptive topology control (ATC) is an important and versatile tool in the optimization of wireless networks. ATC can be implemented in different layers of the protocol stack, such as at the physical layer by power control and at the network layer through routing protocols. In this work, ATC is provided by changing the network nodes' transmission range by controlling transmit power at the physical layer. This leads to a change in both the number of hops that a packet travels and the transmission rates of the links, due to the signal to noise power ratio. The impact of ATC on the network performance is demonstrated through simulation studies employing a standard medium access control protocol and channel models. The simulation studies show that ATC can significantly alter the behavior of the network. It is observed that ATC through power and rate adjustment can improve the network performance by 27% when compared with non-adaptive topology control. © 2014 IEEE.

Source title: 2014 27th Biennial Symposium on Communications, QBSC 2014

DOI: 10.1109/QBSC.2014.6841199

Link: Adaptive topology control to improve network performance through power and rate adaptation

Ahmed, S.; Rahman, K.A.; Al Rubeaai, S.; Colman, G.; Tepe, K.
Remarks on the feasibility of full-wave analyses of printed lens/transmitarray antennas

Year: 2014

Abstract: The full-wave analysis of a specific type of printed lens antenna is performed using the commercial code HFSS. This is done with the antenna operating in the receive mode and then in the transmit mode. The feasibility and usefulness of such computations is demonstrated. © 2014 IEEE.

Source title: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest)

DOI: 10.1109/APS.2014.6904961

Link: Remarks on the feasibility of full-wave analyses of printed lens/transmitarray antennas

Almajali, E.; McNamara, D.A.; Gagnon, N.; Petosa, A.
Feed image lobes in offset-fed reflectarrays: Diagnosis and solution

Year: 2014

Abstract: The actual source of the "feed image lobe" in fixed-beam single-layer offset-fed reflectarrays composed of variable-size patch or dipole elements is diagnosed using a novel technique based on determining the individual contributions of the conduction currents on the reflectarray elements and the groundplane, to the reflectarray scattered fields. The behavior of the feed image lobe is studied over a range of frequencies about the center frequency, and this is used to establish the fact that both the elements and the groundplane are responsible for the presence of the feed image lobe. We show how to reduce or eliminate the feed image lobe at off-center frequencies in offset-fed reflectarrays through use of sub-wavelength reflectarrays instead of conventional reflectarrays with half-wavelength inter-element spacing. Measured and full-wave predicted results are used in all discussions. © 2013 IEEE.

Source title: IEEE Transactions on Antennas and Propagation

Series Number: Volume 62 Issue 1

DOI: 10.1109/TAP.2013.2288977

Link: Feed image lobes in offset-fed reflectarrays: Diagnosis and solution

Almajali, E.; McNamara, D.A.; Shaker, J.; Chaharmir, M.R.
Experimental assessment of snow-induced attenuation on an Earth-space link operating at Ka-band

Year: 2014

Abstract: This investigation assesses the attenuation induced by snowfall on an experimental slant-path link that monitors the 20.199 GHz beacon signal of the Anik F2 satellite. Beacon data collected at Communications Research Centre Canada (CRC) in Ottawa over 2 years, including the winters of 2010-2011 and 2011-2012, were analyzed as part of this study. The antenna of one of the two receivers used in the propagation campaign with Anik F2 was shielded, the first year under a tent and the second year under the roof of a building, in order to prevent degradations on the measured beacon signal due to snow or ice accumulation on the parabolic reflector surface. One of the main challenges of the study was the unambiguous identification of snow events. Information provided by several weather sensors, a profiling radiometer, and meteorological reports were used to help identify the type of precipitation. Events of wet and dry snow along with freezing rain are presented and discussed. Radiometric measurements of sky noise temperature were particularly useful to detect light snowfall events and to estimate event durations. Statistics of snow attenuation were derived for the winter months of the study. It is found that snow attenuation is modest at 20.2 GHz; however, modest attenuation may be important for small-margin communication systems. ©2014. American Geophysical Union. All Rights Reserved.

Source title: Radio Science

Series Number: Volume 49 Issue 10

DOI: 10.1002/2014RS005547

Link: Experimental assessment of snow-induced attenuation on an Earth-space link operating at Ka-band

Amaya, C.; Garcia-Rubia, J.-M.; Bouchard, P.; Nguyen, T.
Impact analysis of wind farms on telecommunication services

Year: 2014

Abstract: Wind power is one of the fastest-growing technologies for renewable energy generation. Unfortunately, in the recent years some cases of degradation on certain telecommunication systems have arisen due to the presence of wind farms, and expensive and technically complex corrective measurements have been needed. This paper presents a comprehensive review on the impact of wind turbines on the telecommunication services. The paper describes the potential affections to several telecommunication services, the methodology to evaluate this impact, and mitigation measures to be taken in case of potential degradation, both preventive and corrective. The telecommunication services included in this review are those that have demonstrated to be more sensitive to nearby wind turbines: weather, air traffic control and marine radars, radio navigation systems, terrestrial television and fixed radio links. The methods described in the paper allow a thorough case-by-case analysis before the wind farm is installed, taking into account the particular features of each installation and the involved services. The prediction of the potential impact makes it possible to propose alternative solutions in order to assure the coexistence between the wind turbines and the telecommunication services. © 2014 The Authors.

Source title: Renewable and Sustainable Energy Reviews

Series Number: Volume 32

DOI: 10.1016/j.rser.2013.12.055

Link: Impact analysis of wind farms on telecommunication services NOTE: A login may be required to access this site.

Angulo, I.; De La Vega, D.; Cascon, I.; Canizo, J.; Wu, Y.; Guerra, D.; Angueira, P.
On-chip, single-shot characterization of GHz-rate complex optical signals

Year: 2014

Abstract: Phase reconstruction based on optical ultrafast differentiation is implemented using an integrated-waveguide Mach-Zehnder interferometer to demonstrate self-referenced phase characterization of gigahertz-rate complex modulated signals (e.g., quadrature phase shift keying and amplitude phase shift keying modulation formats), through a single-shot and realtime technique. This method is transparent to both modulation format and bit rate, limited only by the bandwidth capabilities of the temporal intensity measurement instrumentation. © 2014 IEEE.

Source title: IEEE Photonics Technology Letters

Series Number: Volume 26 Issue 23

DOI: 10.1109/LPT.2014.2354636

Link: On-chip, single-shot characterization of GHz-rate complex optical signals

Bazargani, H.P.; Quelene, J.-B.; Dumais, P.; Malacarne, A.; Clerici, M.; Morandotti, R.; Callender, C.L.; Azana, J.
A multiobjective optimization approach for optimal link adaptation of OFDM-based cognitive radio systems with imperfect spectrum sensing

Year: 2014

Abstract: A transmission technique was analyzed with improved capability to achieve high data rates while allowing more efficient coexistence of radio systems by limiting interference to adjacent spectrum users.

Source title: IEEE Transactions on Wireless Communications

Series Number: Volume 13 Issue 4

DOI: 10.1109/TWC.2014.022114.131948

Link: A multiobjective optimization approach for optimal link adaptation of OFDM-based cognitive radio systems with imperfect spectrum sensing

Bedeer, E.; Dobre, O.A.; Ahmed, M.H.; Baddour, K.E.
Rate-interference tradeoff in OFDM-based cognitive radio networks

Year: 2014

Abstract: In cognitive radio (CR) networks, secondary users (SUs) are allowed to opportunistically access the primary users (PUs) spectrum to improve the spectrum utilization; however, this increases the interference levels at the PUs. In this paper, we consider an orthogonal frequency division multiplexing OFDM-based CR network and investigate the tradeoff between increasing the SU transmission rate (hence improving the spectrum utilization) and reducing the interference levels at the PUs. We formulate a new multiobjective optimization (MOOP) problem that jointly maximizes the SU transmission rate and minimizes its transmit power, while imposing interference thresholds to the PUs. Further, we propose an algorithm to strike a balance between the SU transmission rate and the interference levels to the PUs. The proposed algorithm considers the practical scenario of knowing partial channel state information (CSI) of the links between the SU transmitter and the PUs receivers. Simulation results illustrate the performance of the proposed algorithm and its superiority when compared to the work in the literature. © 2014 IEEE.

Source title: 2014 IEEE Global Communications Conference, GLOBECOM 2014

DOI: 10.1109/GLOCOM.2014.7037279

Link: Rate-interference tradeoff in OFDM-based cognitive radio networks

Bedeer, E.; Dobre, O.A.; Ahmed, M.H.; Baddour, K.E.
Inter-cell handoff performance improvement in LTE-A multi-hop relay networks

Year: 2014

Abstract: Multi-hop relay technology is one of the most promising candidate technologies to overcome the coverage and capacity problem in LTE-Advanced networks. Currently 3GPP is considering the incorporation of multi-hop relays into Release 12 of LTE-A standards. However, many issues remain to be resolved due to the complexity of multi-hop relaying paradigm, specifically resource allocation and mobility management. In this work we focus on the relay selection problem, where a user may have in his range several relay nodes to choose. The conventional selection scheme is based on the channel condition between the relay and the user, such that the user will achieve a high level of throughput. Alternatively we propose in this paper a novel relay selection strategy taking handoff into account over LTE-A multi-hop relay networks. Our goal is to achieve significant performance improvement against legacy centralized resource allocation and handoff algorithms such as disjoint path relay selection. Simulation results show that our design has the advantage of reducing inter-cell handoff frequency and lowering handoff failure ratio.

Source title: MobiWac 2014 - Proceedings of the 12th ACM International Symposium on Mobility Management and Wireless Access

DOI: 10.1145/2642668.2642672

Link: Inter-cell handoff performance improvement in LTE-A multi-hop relay networks

BenMimoune, A.; Khasawneh, F.A.; Kadoch, M.; Sun, S.; Rong, B.
Improved tile format of stereoscopic video for 3-D TV broadcasting

Year: 2014

Abstract: Tile format is a new frame packing arrangement for the first generation of 3-D TV broadcasting services. It puts the left-and right-eye images of each stereoscopic image pair into a single composition frame that allows the service provider to reuse existing production and distribution infrastructure for offering 3-D TV services. Different from frame compatible formats, the tile format composition does not down-sample the left-and right-eye images and, thus, provides a higher video quality for both 3-D and 2-D display. The problem with the tile format is that it creates artificial edges in the right-eye image and introduces visible tiling artifacts around the artificial edges after compression. This brief paper presents a simple modification to the tile format composition method that significantly reduces the tiling artifacts. Experimental results show that local PSNRs around artificial edges are improved by over 1 dB. © 1963-12012 IEEE.

Source title: IEEE Transactions on Broadcasting

Series Number: Volume 60 Issue 1

DOI: 10.1109/TBC.2014.2306038

Link: Improved tile format of stereoscopic video for 3-D TV broadcasting

Blanchfield, P.; Wang, D.
Vivaldi Antenna for MM-Wave Communications

Year: 2014

Abstract: The paper is a tutorial explaining the various design and fabrication considerations for developing a type of slot antenna known as a balanced antipodal Vivaldi antenna for operation in the 60 GHz band.

Source title: High Frequency Electronics Magazine

DOI: N/A

Link: Vivaldi Antenna for MM-Wave Communications

Brzezina, G.; Amaya, R.; Petosa, A.; Roy, L.
Broadband and compact Vivaldi arrays in LTCC for 60 GHz point-to-point networks

Year: 2014

Abstract: This paper presents two new Vivaldi antenna array topologies that operate in the 60 GHz range. Their small size and end-fire radiation make them suitable for future 802.11ad mobile terminals. Both the two- and four-element arrays are fed by a stripline feed network that is inherently well isolated from its surroundings. A stripline-to-microstrip transition is incorporated in each array feed so that standard V-connectors can be used to conduct measurements. Low temperature co-fired ceramic (LTCC) technology is used to realize the multilayered antenna prototypes. Results from within an anechoic chamber are in good agreement with simulations and show peak gains up to 11.57 dBi and impedance bandwidths that cover most of the range from 59 to 64 GHz. These characteristics make the proposed antenna arrays suitable candidates for use in wireless modules for point-to-point networks. © 2014 IEEE.

Source title: 2014 IEEE 15th Annual IEEE Wireless and Microwave Technology Conference, WAMICON 2014

DOI: 10.1109/WAMICON.2014.6857763

Link: Broadband and compact Vivaldi arrays in LTCC for 60 GHz point-to-point networks

Brzezina, G.; Amaya, R.E.; Petosa, A.; Roy, L.
Design and analysis of a low-profile directive antenna array for multi-element terminals

Year: 2014

Abstract: The authors verify the benefits of directivity for a 4 × 4 multiple-input multiple-output (MIMO) system in a non-lineof- sight indoor propagation environment. A novel prototype with four directive antennas has been designed to have full aggregate azimuth coverage, which is conveniently achieved without the need for electronic or mechanical beam-steering. In this way, it captures similar multipath content to that of an equivalent omnidirectional device as confirmed by the field measurements. This coupled with the inherently larger gain of directive antennas renders the prototype a better choice for multi-antenna receivers. The prototype design makes it possible to use a simple but effective power-based antenna selection algorithm. Importantly, this algorithm achieves close to the theoretical maximum channel capacity when only two radio frequency chains are available at the receiver. For the first time, these results show that in an MIMO indoor environment directive receive antennas are a viable option. © Crown 2014.

Source title: IET Microwaves, Antennas and Propagation

Series Number: Volume 8 Issue 8

DOI: 10.1049/iet-map.2013.0459

Link: Design and analysis of a low-profile directive antenna array for multi-element terminals

Brzezina, G.; Basri, A.A.; Ghasemi, A.; Sydor, J.; Vukovic, A.
Exploring the disruptive edge of coalition network management

Year: 2014

Abstract: In 2009 The Technical Cooperation Program (TTCP) Policy Enabled Coalition Communications (PECC) environment Project Arrangement (PA) officially began to investigate scalable and distributed network management and control approaches that addressed policy-enabled networking, management and security across different coalition domains. This paper highlights the progress of the work undertaken: the characterisation of military coalition networks, and the creation of both a framework for Quality of Protection (QoP) via overlay networks and techniques for policy based network management in coalition black core networks. Finally, the application of QoP to develop a mechanism for trust based path selection is explored. © 2014 IEEE.

Source title: Proceedings - IEEE Military Communications Conference MILCOM

DOI: 10.1109/MILCOM.2014.33

Link: Exploring the disruptive edge of coalition network management

Burnop, T.; St-Onge, F.; Haines, J.; George, P.
ITU Handbook on Radiometeorology (2nd edition)

Year: 2014

Abstract: This Handbook provides information on radiometeorology, the branch of meteorology that studies the effects of the atmosphere on the propagation of radio waves. Topics covered in the Handbook include: physical characteristics of the atmosphere, atmospheric refraction, attenuation of radio waves due to atmospheric gases, rain, ice and snow.

Source title: ITU (International Telecommunication Union)

DOI: N/A

Link: ITU Handbook on Radiometeorology (2nd edition)

César, A.; Bouchard, P.
Design of an FSS-backed 20/30 GHz circularly polarized reflectarray for shared aperture X/Ka-band satellite applications

Year: 2014

Abstract: A 20/30GHz Frequency Selective Surface (FSS)-backed reflectarray is introduced in this paper. This reflectarray is designed as part of a shared aperture reflectarray for simultaneous operation at X- and Ka-band. The reflectarray is illuminated with a circularly polarized (CP) feed and the elements are designed to collimate the beam in a desired direction. Separate reflectarrays with frequency selective surface (FSS) as the ground plane was designed for both receive (20 GHz) and transmit (30 GHz) bands. This FSS-backed reflectarray will be located on the top of an X-band reflectarray with a solid ground and the FSS structure is designed to maximize the transmission at X-band. © 2014 IEEE.

Source title: Proceedings - ANTEM 2014: 2014 16th International Symposium on Antenna Technology and Applied Electromagnetics

DOI: 10.1109/ANTEM.2014.6887697

Link: Design of an FSS-backed 20/30 GHz circularly polarized reflectarray for shared aperture X/Ka-band satellite applications

Chaharmir, M.R.; Shaker, J.
Design of a multi-layer Ka-band frequency selective surface-backed reflectarray for satellite applications

Year: 2014

Abstract: A multi-band reflectarray structure that transmits and receives at both Ka- and X-bands is introduced in this paper. A separate reflectarray is designed for each band and a frequency selective surface (FSS) is used as the ground plane for the Ka-band reflectarray. Additional FSS's are implemented to further enhance the isolation between bands. The reflectarrays also implement a circular to linear polarized transformation which results in a simplified feed geometry. © 2014 European Association on Antennas and Propagation.

Source title: 8th European Conference on Antennas and Propagation, EuCAP 2014

DOI: 10.1109/EuCAP.2014.6902048

Link: Design of a multi-layer Ka-band frequency selective surface-backed reflectarray for satellite applications

Chaharmir, M.R.; Shaker, J.
When vehicles meet TV white space: A QoS guaranteed dynamic spectrum access approach for VANET

Year: 2014

Abstract: Vehicular ad hoc network(VANET) is an emerging wireless communication scenario and has caught the attentions of both academia and industry. However, some challenges still exist, one of which is the spectrum scarcity problem, especially for the throughput-demanding downlink infotainment services. In this paper, we present a solution to the problem by introducing the state-of-the-art cognitive radio technology, namely the exploitation of TV white space(TVWS). First, we give an overview of the compositions of this new networking paradigm. Then, taking into account the characteristics of both VANET and TVWS, we develop a novel TVWS resource model tailored for the system. After that, we focus on the dynamic spectrum access problem and formulate it as a matching between vehicles/requests and available channels. Both the throughput of the network and the guarantee of QoS are considered during the calculation of preference lists. Furthermore, an algorithm is also brought forth to implement the matching process. It is proved that after the execution of the algorithm, the matching is stable and vehicle-optimal. Numerical results demonstrate the feasibility and efficiency of our system. © 2014 IEEE.

Source title: IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, BMSB

DOI: 10.1109/BMSB.2014.6873511

Link: When vehicles meet TV white space: A QoS guaranteed dynamic spectrum access approach for VANET

Chen, J.; Liu, B.; Zhou, H.; Wu, Y.; Gui, L.
Distributed interference alignment for mobile MIMO systems based on local CSI

Year: 2014

Abstract: The requirement for global channel state information (CSI) throughout the network is a significant hurdle to overcome in interference alignment (IA) technologies for mobile applications. In this letter, a distributed IA algorithm is proposed that uses local CSI at the receivers to determine desirable precoding matrices for all interfering transmitters. These matrices are fed back to the transmitters where they are combined, using scalar weighting, to determine the next set of transmit precoding matrices. Results herein show that, with equivalent feedback limitations, the proposed algorithm provides better SINR performance than an IA algorithm requiring full CSI-based feedback, due to the smaller dimensions of the precoding matrices. © 2014 IEEE.

Source title: IEEE Communications Letters

Series Number: Volume 18 Issue 7

DOI: 10.1109/LCOMM.2014.2325024

Link: Distributed interference alignment for mobile MIMO systems based on local CSI

Colman, G.W.K.; Muruganathan, S.D.; Willink, T.J.
Interference-aware power coordination game for ISM bands

Year: 2014

Abstract: The use of wireless equipment in the already-overcrowded ISM bands had been further growing in recent years. This increase leads to high interference levels, which causes unstable communication and an average throughput reduction in heavily-used channels. This calls for more robust, interference-aware means of channel-access for Wi-Fi and similar wireless devices in ISM bands. In this paper, we propose a Game Theory (GT) based power allocation mechanism for IEEE 802.11 networks, which might incorporate some aspects of Cognitive Radio (CR) functionality. Up to now operation of 802.11 devices was constrained by regulations in terms of maximum transmission power, in order to limit the extent of interference from uncoordinated emissions. Our proposed mechanism, with its feasibility backed by the practical experimentation reported in this paper, would allow embracing lighter regulatory rules or complete abolition of power limits for unlicensed access in ISM bands. Moreover, our proposed concept of channel access based on power balancing game might also make unnecessary the use of CSMA/CA protocol. © 2014 ICST.

Source title: Proceedings of the 2014 9th International Conference on Cognitive Radio Oriented Wireless Networks and Communications, CROWNCOM 2014

DOI: 10.4108/icst.crowncom.2014.255367

Link: Interference-aware power coordination game for ISM bands

Cuzanauskas, T.; Medeisis, A.; Haddad, Y.; Anskaitis, A.; Cremene, L.C.; Sydor, J.; Holland, O.D.; Nekovee, M.
Perceptual quality-driven resource allocation in energy-aware wireless video multicasting

Year: 2014

Abstract: In conjunction with the rising trend towards consumption of resource-hungry multimedia content over wireless medium, efficient radio resource allocation (eRRA) represents an ongoing challenge to network operators. This paper explores the application of multicasting in light of an eRRA that considers the perceptual quality aspect of wireless video transmission such that transmission energy is minimized. A multiuser orthogonal frequency-division multiplexing (OFDM) environment is considered. The resource allocation scheme presented is based on the genetic algorithm (GA) and offers fairness through the balance of average perceptual quality and minimal total energy among all subscribers in multicasting groups. In order to assist with this balance, a utility function is introduced as a fitness function for the GA. The allocation scheme relies on a well-established video quality model (VQM) for assessment of user-perceived quality. Simulation results show that the allocation scheme helps to preserve the energy requirement at low levels despite the proportionate rise in the number of subscribers. Moreover, perceived quality is well-secured and maintained at high levels, with a consistent increase of the utility value. Reflecting on today's consumption patterns of popular video content, adoption of the presented scheme in multicasting would help lessen the carbon footprint emitted by wireless communications, while consumers' quality of experience (QoE) is maintained. © 2014 ICST.

Source title: Proceedings of the 2014 10th International Conference on Heterogeneous Networking for Quality, Reliability, Security and Robustness, QSHINE 2014

DOI: 10.1109/QSHINE.2014.6928667

Link: Perceptual quality-driven resource allocation in energy-aware wireless video multicasting

Danish, E.; Fernando, A.; Abdul-Hameed, O.; Pourazad, M.
Experimental characterization of building shadowing and exit loss in a small-cell environment at 700, 2600 and 4900 MHz

Year: 2014

Abstract: Results are presented of propagation measurements at 700, 2600 and 4900 MHz, in an environment representative of expected small-cell deployments, i.e., with the transmitting antenna located below the rooftop of a nearby building and/or indoors. Building shadowing and exit loss are estimated by comparing spatial propagation loss distributions measured in the area around a transmitting antenna located, alternately, at various heights outside a building, and on different storeys inside the building. © 2014 European Association on Antennas and Propagation.

Source title: 8th European Conference on Antennas and Propagation, EuCAP 2014

DOI: 10.1109/EuCAP.2014.6902532

Link: Experimental characterization of building shadowing and exit loss in a small-cell environment at 700, 2600 and 4900 MHz

De Jong, Y.L.C.; Bouchard, P.; Shewan, G.D.
The Economics of Spectrum and Related Business Models

Year: 2014

Abstract: This is a report looks at the current state of Dynamic Spectrum Sharing research and development around the world.

Source title: Dynamic Spectrum Sharing Annual Report

DOI: N/A

Link: The Economics of Spectrum and Related Business Models

Dumoulin, S.; Sydor, J.; Chester, D.; D'Arcy, P.; Choi, J.; Holland, O.; Lamont, L.; Marojevic, V.; Mitola, J.; Romano, F.; Uhm, M.; Baddour, K.; Buchwald, G.; Dietrich, C.; Devasirvatham, D.; Dwyer, J.; Glossner, J.; Leschhorn, R.; Oberlies, B.; Reed, J.
Multiport antenna performance analysis from ray-traced channels for small cells

Year: 2014

Abstract: The evaluation of multi-element antenna (MEA) performance in urban environments is particularly important for the planning and design of reliable, spectrally efficient systems. To date, MIMO communication using large dimensions has not been implemented for commercial systems. But the potential capacity of MIMO is much more significant when the MIMO dimensions become large. The hold-up is not just the shortfall in understanding how to deploy large-dimension MIMO, but also how to design the antenna systems. There is no widely agreed method for evaluating MEAs used by MIMO communications. Even the performance evaluation of a well-established MIMO configuration, such as the small scale systems already used, remains limited. The evaluation often defers to OTA tests in artificial environmental conditions. The real-world performance remains unclear, so care must be taken in design optimization. In this paper, we discuss the incorporation of some physical modeling of the propagation environment to evaluating the MEA performance for a typical urban wireless channel. A ray-optic method is applicable to any 3D environment, and any number of antennas with arbitrary patterns. In this sense it offers a practical approach for large-dimension MIMO evaluation by being able to change the antennas and the environment, all in software. The evaluation method is illustrated by using an MEA slot cube (12 antennas) operating in a specific environment, namely downtown Ottawa. © 2014 European Association on Antennas and Propagation.

Source title: 8th European Conference on Antennas and Propagation, EuCAP 2014

DOI: 10.1109/EuCAP.2014.6902535

Link: Multiport antenna performance analysis from ray-traced channels for small cells

Estarki, M.D.; Yun, J.X.; De Jong ,Y.L.C.; Vaughan, R.G.
Reflectarray design with similarity-shaped fragmented sub-wavelength elements

Year: 2014

Abstract: A new technique for synthesizing reflectarray antennas is presented. It utilizes fragmented elements in a manner that allows the elements of the reflectarray to be shaped-optimized so that a high degree of geometrical similarity is maintained between adjacent elements. The implication is that in a reflectarray of such elements each element will see an electromagnetic environment that more closely emulates the infinite periodic one used to compute the element properties. We show experimentally that this indeed results in aperture efficiencies closely approaching the upper bounds achievable for some selected feed system, and offers a significant improvement over that obtained with conventional reflectarrays (that is, those not using similarity-synthesized fragmented elements). It is also shown that a reflectarray surface that uses fragmented elements can be simultaneously patterned with a visual image while still closely maintaining the desired reflection phase from its surface to yield a high-gain antenna. © 2014 IEEE.

Source title: IEEE Transactions on Antennas and Propagation

Series Number: Volume 62 Issue 9

DOI: 10.1109/TAP.2014.2330578

Link: Reflectarray design with similarity-shaped fragmented sub-wavelength elements

Ethier, J.L.T.; McNamara, D.A.; Chaharmir, M.R.; Shaker, J.
A 3-state hypothesis test model for cognitive radio systems

Year: 2014

Abstract: This paper presents a cognitive engine that is applied to dynamic channel selection and parameter configuration of opportunistic spectrum users. This engine uses a 3-state hypothesis test model to make ternary decisions about channel status: vacant, underutilized, or congested. A simple autoregressive model is also used to rank channels taking channel history into considerations. The set of ranked channels is stored in a look-up table. An opportunistic user seeking a channel for its transmission uses the look-up table to access a vacant channel or share the best underutilized channel. Channel selection and parameter configuration are performed on Wi-Fi data collected using a test-bed of 16 sensors operating in the 2.4 GHz ISM band in an outdoor urban radio environment. Mining sensed data showed underutilized spectrum with a sufficient room for opportunistic spectrum use. Mining sensed data also favored making autonomous channel status decisions. In addition, a detection metric based on channel occupancy time is favored over the energy based received signal strength indicator (RSSI). A comparative performance is presented between 2-state and 3-state hypothesis test models with detection metrics based on signal energy and channel occupancy time. Using a 3-state hypothesis test model instead of a 2-state model has made more channels available for opportunistic spectrum use where underutilized channels can be shared instead of being classified busy. © 2014 IEEE.

Source title: 2014 IEEE International Symposium on Dynamic Spectrum Access Networks, DYSPAN 2014

DOI: 10.1109/DySPAN.2014.6817806

Link: A 3-state hypothesis test model for cognitive radio systems

Hanna, S.A.
60 GHz optically transparent microstrip antenna made of meshed AuGL material

Year: 2014

Abstract: In this study, a 60 GHz optically transparent microstrip (OTM) patch antenna array is designed, fabricated and measured. Gold meshes are implemented for the two layers of the antenna. A numerical parametric study on the positioning of the two meshed layers is performed to give design considerations and optimise both the electromagnetic and optical performances of OTM antennas at 60 GHz band. The simulation and measured results of the OTM antenna with a theoretical maximum transparency up to 74.6% are compared with a light reflecting reference antenna. Both antennas have similar reflection coefficients and radiating performances. This study provides practical design rules to fabricate high gain OTM antennas with performances similar to those of standard topologies at 60 GHz band, with the addition of high optical transparency. © The Institution of Engineering and Technology 2014.

Source title: IET Microwave Antennas Propagation

DOI: 10.1049/iet-map.2013.0564

Link: 60 GHz optically transparent microstrip antenna made of meshed AuGL material

Hautcoeur, J.; Talbi, L.; Hettak,K.; Nedil, M.
Flexible plastic-based inkjet printed CPW fed dipole antenna for 60 GHz ISM applications

Year: 2014

Abstract: This study investigates an inkjet-printed millimeter wave antenna on PET (polyethylene terephthalate) substrate. The 60 GHz CPW (coplanar waveguide) fed dipole antenna, was printed with a Dimatix inkjet printer using silver nanopPublished Paper/Article colloidal ink. First, this process uses a plasma polymerization technique to prepare the PET surface for printing. Then, the silver ink lines are printed on the PET substrate, followed by curing in an oven, to remove excess solvent. The silver ink layer conductivity is around 4 × 106 Siemens/m. The measured impedance bandwidth of the printed antenna, defined by return loss at -10 dB, is 4GHz, from 58 to 62 GHz. © 2014 IEEE.

Source title: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest)

DOI: 10.1109/APS.2014.6904496

Link: Flexible plastic-based inkjet printed CPW fed dipole antenna for 60 GHz ISM applications

Hettak, K.; Petosa, A.; James, R.
Flexible plastic substrate-based inkjet printed CPW resonators for 60 GHz ISM applications

Year: 2014

Abstract: This study investigates inkjet-printed millimetre-wave coplanar waveguide (CPW) series tuning stubs printed on flexible plastic substrates such as Polyethylene Terephthalate (PET). These CPW resonators exhibit a bandpass/bandstop response that is useful for microwave and millimetre-wave filtering applications. The 60GHz CPW resonators were printed with a DMP-2800 series inkjet printing system. A silver nanoparticle colloidal solution was used as the printing ink. First, this process uses a plasma polymerization technique to improve the PET surface for printing. Next, silver lines are inkjet printed on the PET substrate and cured in an oven to remove excess solvent and material impurities. The experimental prototypes presented in this paper demonstrate the efficiency of the design method and the feasibility of creating CPW resonators using inkjet printing technology. © 2014 European Microwave Association

Source title: European Microwave Week 2014: Connecting the Future, EuMW 2014 - Conference Proceedings; EuMC 2014: 44th European Microwave Conference

DOI: 10.1109/EuMC.2014.6986655

Link: Flexible plastic substrate-based inkjet printed CPW resonators for 60 GHz ISM applications

Hettak, K.; Ross, T.; James, R.; Momciu, A.; Wight, J.
A new type of Robust broadband GaN HEMT-based high power high-pass/low-pass 22.5° phase shifter

Year: 2014

Abstract: This Published Paper/Article proposes a new type of GaN HEMT-based high power phase shifter operating at X-band. The design includes a 22.5° phase shift network and a high power SPDT switch. The design and resulting performance are discussed in detail and are confirmed by experimental and simulation results, which are in good agreement up to 20 GHz. The one bit phase shifter exhibits good phase performance, insertion loss, and return loss. The proposed phase shifter MMIC has been successfully demonstrated using a 0.5 µm gate GaN HEMT process. © 2014 Wiley Periodicals, Inc.

Source title: Microwave and Optical Technology Letters

Series Number: Volume 56 Issue 2

DOI: N/A

Link: A new type of Robust broadband GaN HEMT-based high power high-pass/low-pass 22.5° phase shifter

Hettak, K.; Ross, T.N.; Cormier, G.; Wight, J.S.
A low-cost small-size 60 GHz quadrature coupler for IPD-based SiP radio systems

Year: 2014

Abstract: A reduced-size 60-GHz coplanar-waveguide (CPW) branch-line coupler has been demonstrated in integrated passive device (IPD) technology and is presented in this paper. The fabricated coupler has a size-reduction of more than 85% compared to that of a conventional CPW branch-line coupler. The size reduction is achieved by utilizing CPW transmission lines loaded with microstrip open-circuited stubs as capacitive elements. The measured results at the coupler's output ports showed a phase error of less than 3 degrees and an amplitude imbalance of less than 1.3 dB over the frequency band of 57-64 GHz. The measurements also showed an insertion loss of less 1 dB and return losses better than 14 dB over the frequency band of interest. The proposed coupler is well suited for use in low cost high performance System-in-Package (SiP) V-band radio front-ends for high data rate wireless applications. Copyright 2014 IEICE.

Source title: 2014 Asia-Pacific Microwave Conference Proceedings, APMC 2014

DOI: N/A

Link: A low-cost small-size 60 GHz quadrature coupler for IPD-based SiP radio systems

Hsu, Y.-C.; Haroun, I.; Chang, D.-C.; Amaya, R.; Hettak, K.
Security in wireless multimedia communications

Year: 2014

Abstract: With the proliferation of mobile devices and the popularity of mobile multimedia applications, systematic research of the overall aspects of security in mobile multimedia communications is crucial. The emerging mobile wireless multimedia communications can be used for various pervasive and ubiquitous applications in consumers, businesses, and government agencies. Besides the consumer cellular systems and residential homes, mobile devices are being rapidly integrated into enterprises with the increase in bring-your-own-device (BYOD) in many organizations. As mobile multimedia communications become more popular in both the consumer and business markets, the need for tighter security is inevitable.

Source title: IEEE Communications Magazine

Series Number: Volume 52 Issue 3

DOI: 10.1109/MCOM.2014.6766085

Link: Security in wireless multimedia communications

Hu ,R.; Rong, B.; Wang, C.; Qian, Y.; Chen, H.-H.
Robust broadcasting in tactical networks using network coding

Year: 2014

Abstract: Broadcasting (communicating information from one to all or many to all nodes in a network) is an important communication primitive in tactical networks. To reduce the spectral cost of broadcast, instead of using simple flooding, many proposed broadcast protocols such as the Simplified Multicast Forwarding (SMF) employ local topology information to decrease the number of packet retransmissions. The performance of such optimizations depends on the accuracy of the topology information. In this work, we propose an alternative approach that is based on network coding. This protocol determines, based on a node's view of its local topology, how many coded packets each node rebroadcasts. Our results show that network-coding based broadcasting has lower spectral cost and is more robust to partial/inaccurate local topology knowledge than protocols based on SMF. © 2014 IEEE.

Source title: Proceedings - IEEE Military Communications Conference MILCOM

DOI: 10.1109/MILCOM.2014.203

Link: Robust broadcasting in tactical networks using network coding

Kunz, T.; Li, L.
Analysis on two dimensional block interleaver for the cloud transmission system

Year: 2014

Abstract: This paper analyzes a interleaver size and its complexity of 2D block code, which consists of vertical raptor-like rate-compatible LDPC code and horizontal Reed Solomon (RS) code. An adequate size of 2D interleaver should be reasonably chosen by considering not only the performance and user satisfaction, but also the required memory size at a receiver side. © 2014 IEEE.

Source title: IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, BMSB

DOI: 10.1109/BMSB.2014.6873530

Link: Analysis on two dimensional block interleaver for the cloud transmission system

Kwon, S.; Park, S.I.; Wu, Y.; Lee, J.-Y.; Kim, H.M.; Hur, N.; Kim, J.
EM Channel Characteristics and their Impact on MAC Layer Performance in Underwater Surveillance Networks

Year: 2014

Abstract: In this paper, we discuss the characteristics of electromagnetic channels in seawater. We also implement in a network simulator an underwater surveillance network using electromagnetic channels to study its performance.

Source title: Wireless Communications and Mobile Computing

DOI: 10.1002/wcm.2461

Link: EM Channel Characteristics and their Impact on MAC Layer Performance in Underwater Surveillance Networks

Li, J.; Toulgoat, M.
Propagation modeling and MAC-layer performance in EM-based underwater sensor networks

Year: 2014

Abstract: Electromagnetic (EM) waves have been considered as an alternative to acoustic communications in seawater. In this paper, we propose a propagation model for EM channels in seawater and study the MAC-layer performance in EM-based underwater sensor networks. We implement the communication characteristics of EM channels in seawater and an EM-based underwater surveillance network in the QualNet network simulator to evaluate the performance of MAC techniques including Aloha, multiple access with collision avoidance (MACA), carrier sense multiple access without acknowledgement (CSMAWithoutACK), and carrier sense multiple access with acknowledgement (CSMAWithACK). Simulation results show that CSMAWithoutACK and CS-MAWithACK outperforms Aloha and MACA in terms of the packet average delay, the packet delivery ratio, and the scheme overhead. CSMAWithoutACK achieves lower packet delay and scheme overhead values than CSMAWithACK, and thus is the most appropriate MAC scheme for EM-based underwater surveillance networks with a relatively low data generation rate. Copyright © 2014 ACM.

Source title: DIVANet 2014 - Proceedings of the 4th ACM Symposium on Development and Analysis of Intelligent Vehicular Networks and Applications

DOI: 10.1145/2656346.2656359

Link: Propagation modeling and MAC-layer performance in EM-based underwater sensor networks

Li, J.; Toulgoat, M.; Deziel, M.; Yu, F.R.; Perras, S.
Exact analysis on network capacity of airborne MANETs with digital beamforming antennas

Year: 2014

Abstract: Recently, the use of digital beamforming (DBF) antennas has been drawing lots of interest in airborne platforms for resolving the network partition problem in airborne mobile ad hoc networks (MANETs). In this paper, properties of the network capacity of an airborne MANET with DBF antennas are investigated. This paper considers an ad hoc network consisting of a number of uniformly distributed airborne platforms in a bounded area. These platforms are either directly or indirectly connected with each other through DBF antennas, and form an airborne MANET. We first formulate a digital beamforming antenna system model, referred to as the omni-direction plus sector (OPS) model, and then carry out an exact analysis for the network capacity. The OPS model characterizes the radiation pattern of a DBF antenna. Under the condition that a Hamiltonian path exists in the network, an explicit expression is derived for the network capacity. We show that, for fixed values of the OPS model, the network capacity increases as the network size increases until it reaches an optimal value. If the network size continues to increase, the network capacity will decrease until it reaches zero. Explicit expressions for the optimal network size and the maximum network capacity are also obtained. Finally, numerical results are presented. It is shown that both the optimal network size and the maximum network capacity increase as the antenna beamwidth decreases. They increase slowly when the beamwidth is large, but as the antenna beam becomes narrower, they increase faster. Copyright 2014 ACM.

Source title: MSWiM 2014 - Proceedings of the 17th ACM International Conference on Modeling, Analysis and Simulation of Wireless and Mobile Systems

DOI: 10.1145/2641798.2641821

Link: Exact analysis on network capacity of airborne MANETs with digital beamforming antennas

Li, J.; Zhang, C.; Zhou, Y.; Perras, S.; Zhao, Y.Q.
Network properties of mobile tactical scenarios

Year: 2014

Abstract: The mobile tactical network is a practical implementation of the mobile ad hoc network. Formed across tactical radios operating in the military very high frequency and low ultrahigh frequency bands, the mobile tactical network has distinctive characteristics when compared with generic mobile ad hoc networks, in particular with respect to its network topological behaviors and connectivity attributes. These characteristics must be understood and considered when selecting suitable network protocols. To this end, in this paper, a network science-based systematic modeling approach is applied to analyze typical deployment scenarios and identify fundamental tactical network properties. The novel framework employs realistic scenario models as well as radio physical layer performance parameters and channel models to effectively capture the dynamic network behavior that needs to be considered for protocol design. The results provide critical insights and guidance to the development of tactical network solutions. © Her Majesty the Queen in Right of Canada 2013

Source title: Wireless Communications and Mobile Computing

Series Number: Volume 14 Issue 14

DOI: 10.1002/wcm.2320

Link: Network properties of mobile tactical scenarios

Li, L.; Vigneron, P.; Brown, C.; Kunz, T.; Zhuang, W.
A compact UWB band-pass filter with ultra-narrow tri-notch-band characteristic

Year: 2014

Abstract: This paper proposes a novel approach for designing compact ultra-wideband (UWB) band-pass filter with a good tri-notch-band characteristic, which is obtained by using the ring-stub multimode resonator (MMR). The equivalent model of the filter is achieved by using odd/even excitation resonance condition. The characteristics of the designed filter are investigated and analyzed by means of IE3D. This filter is designed, analyzed, fabricated, and measured successfully. Experimental and numerical results show that the proposed filter, with compact size of 25 × 10mm2, has an impedance bandwidth range from 3 GHz to 10.6 GHz with the triple notch bands at 4.14 GHz, 6.1 GHz, and 7.1 GHz. The proposed filter can be incorporated into UWB radio systems in order to efficiently enhance the interference immunity from undesired signals. © 2014 ACES.

Source title: Applied Computational Electromagnetics Society Journal

Series Number: Volume 29 Issue 2

DOI: N/A

Link: A compact UWB band-pass filter with ultra-narrow tri-notch-band characteristic NOTE: A login may be required to access this site.

Li, Y.; Li, W.; Liu, C.; Ye, Q.
A compact circular slot UWB antenna with multimode reconfigurable band-notched characteristics using resonator and switch techniques

Year: 2014

Abstract: In this Published Paper/Article, we propose a circular slot ultrawideband (UWB) antenna with multimode reconfigurable dual band-notched characteristics. By using a two-stage T-shaped stepped impedance resonator (TS-TSIR) and a parallel stubs loaded resonator (PSLR), dual band-notched function is achieved to reject worldwide interoperability for microwave access, WLAN, and X-band signals. The multimode reconfigurable band-notched characteristic is realized by integrating four switches onto the TS-TSIR and the PSLR. Simulated and measured results show that this antenna, with multimode reconfigurable characteristics and dual band-notched function, can operate from 2.7 to 12 GHz (VSWR<2), which includes the entire UWB band. This antenna maintains omnidirectional radiation patterns that is suitable for UWB applications. © 2014 Wiley Periodicals, Inc.

Source title: Microwave and Optical Technology Letters

Series Number: Volume 56 Issue 3

DOI: 10.1002/mop.28152

Link: A compact circular slot UWB antenna with multimode reconfigurable band-notched characteristics using resonator and switch techniques

Li, Y.; Li, W.; Ye, Q.
A CPW-fed circular wide-slot UWB antenna with dual-notch bands by combining slot and parasitic element techniques

Year: 2014

Abstract: A compact coplanar waveguide fed circular wide-slot antenna with dual-band-notched characteristic is proposed by using an arc-shaped slot (ASS) and an arc-shaped parasitic element (ASPE) for ultra-wideband (UWB) communication applications. The center frequencies of the dual-notch bands can be tuned in a wide range by adjusting the parameters of the ASS and the ASPE. Both the numerical and experimental results show that the proposed antenna can operate over a wide frequency band ranging from 2.7 to 12 GHz with VSWR < 2, with the exception of the two notch bands operating at wireless local area network band and X-band. In addition, the proposed antenna has a compact size and omnidirectional radiation pattern, which is suitable for UWB communication applications. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1240-1244, 2014 Copyright © 2014 Wiley Periodicals, Inc.

Source title: Microwave and Optical Technology Letters

Series Number: Volume 56 Issue 5

DOI: 10.1002/mop.28296

Link: A CPW-fed circular wide-slot UWB antenna with dual-notch bands by combining slot and parasitic element techniques

Li, Y.; Li, W.; Ye, Q.
LDPC-RS product codes for digital terrestrial broadcasting transmission system

Year: 2014

Abstract: Product code is a promising technique for the next generation digital terrestrial broadcasting transmission system, due to its superior error correction performance. In this paper, we propose an Low Density Parity Check-Reed Solomon (LDPC-RS) product code structure, along with a novel hybrid iterative decoding scheme. The decoding scheme combines a hybrid LDPC decoding technique and RS+LDPC hard decision decoding to form a 'turbo-like' decoding structure. By ingeniously ranging the order of different decoding techniques as well as performing error estimation and soft value modification at proper stages, the proposed decoding scheme greatly improves the error performance in low SNR regions while reducing the computational complexity in moderate and high SNR regions compared with the simple concatenation of LDPC and RS decoding. Moreover, we propose a rate compatible LDPC-RS product code to further reduce complexity by adaptively choosing the decoding code rate. Simulation results verify the outstanding error performance and suitability for the energy saving applications. © 1963-12012 IEEE.

Source title: IEEE Transactions on Broadcasting

Series Number: Volume 60 Issue 1

DOI: 10.1109/TBC.2013.2291359

Link: LDPC-RS product codes for digital terrestrial broadcasting transmission system

Liu, B.; Li, Y.; Rong, B.; Gui, L.; Wu, Y.
A frequency reconfigurable patch antenna with reed switches

Year: 2014

Abstract: A frequency reconfigurable patch antenna using 19 reed switches to connect the patch with the ground plane is proposed. Compared with other controlling methods, using reed switches could avoid the need of placing bias and control lines in the vicinity of the radiating elements and the attendant impacts on the antenna radiation performance. Simulated results show that the antenna can be reconfigured to operate in the frequency range from 1.7 GHz to 2.7 GHz. Two working cases of the antenna (resonate at 2.05 GHz and 2.45 GHz) are studied and presented to illustrate the feasibility of this method. © 2014 IEEE.

Source title: 2014 IEEE International Wireless Symposium, IWS 2014

DOI: 10.1109/IEEE-IWS.2014.6864248

Link: A frequency reconfigurable patch antenna with reed switches

Liu, Q.; Wang, N.; Zeng, Q.; Wu, C.; Wei, G.
Antipodal linearly tapered slot antenna array for millimeter-wave base station in massive MIMO systems

Year: 2014

Abstract: For massive MIMO systems, it is very challenging to have the large-scale antennas for a compact base station. This paper presents a 36 sub-sectors for a compact millimeter-wave base station. The antenna array for each sub-sector is comprised of 16 planar high-gain dielectric-loaded antipodal linearly tapered slot antenna (ALTSA) elements arranged in a 4 × 4 configuration. Down to 36 feed ports are required in a base station with 36 × 16 antennas. The realized gain of the antenna array is 25.6 dBi, and the half-power beam widths (HPBW) are 10.7° and 5.3° in H-plane and E-plane, respectively. © 2014 IEEE.

Source title: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest)

DOI: 10.1109/APS.2014.6904887

Link: Antipodal linearly tapered slot antenna array for millimeter-wave base station in massive MIMO systems

Ma, R.; Gao, Y.; Cuthbert, L.; Zeng, Q.
Dynamic Channel Selection in cognitive radio WiFi networks: An experimental evaluation

Year: 2014

Abstract: Increased wireless network intelligence and interference awareness enabled by cognitive radio can lead to improved spectrum utilization and network performance. Using a cognitive radio platform developed by Communication Research Centre Canada (CRC), in this work we propose and implement a novel Dynamic Channel Selection (DCS) algorithm for a network of sectorized WiFi cells. The proposed algorithm leverages the ability of underlying cognitive radio platform to continuously monitor and identify WiFi interference sources and relieves the network operator of having to manually configure and update the channels across the network. The algorithm's performance is evaluated using field experiments in both rural and urban environments which demonstrate significant improvement in terms of spectrum efficiency as well as robustness to variations in the interference. The main contributions of this work include the proposed DCS algorithm as well as offering a prime example of cognitive radio's potential in practical deployments. In addition, an overview of the CORAL platform summarizing its major components and capabilities is provided. © 2014 IEEE.

Source title: 2014 IEEE International Conference on Communications Workshops, ICC 2014

DOI: 10.1109/ICCW.2014.6881206

Link: Dynamic Channel Selection in cognitive radio WiFi networks: An experimental evaluation

Mack, J.; Gazor, S.; Ghasemi, A.; Sydor, J.
Design of a multilayered six-aperture directional coupler using substrate integrated waveguide

Year: 2014

Abstract: The design of a six-aperture, 10-dB directional coupler using substrate integrated waveguide is presented. Size constraints precluded addition of holes in series, however, in parallel the addition enhanced performance without increasing size. Here, 10-dB coupling with ±2 dB coupling ripple and reflection coefficient exceeded that of 15 dB over 34% of bandwidth. © 2014 Wiley Periodicals, Inc.

Source title: Microwave and Optical Technology Letters

Series Number: Volume 56 Issue 1

DOI: 10.1002/mop.28006

Link: Design of a multilayered six-aperture directional coupler using substrate integrated waveguide

Mbaye, M.; Talbi, L.; Hettak, K.
ISM-Advanced: Improved access rules for unlicensed spectrum

Year: 2014

Abstract: Access to unlicensed spectrum has thus far been based on simplistic rules, such as a transmission power limitation, requirement for tolerance of interference, and a relaxed out-of-band transmission mask. Such rules originate from the rudimentary applications originally envisaged for such spectrum, which don't consider the current technical capabilities of radio devices. This paper introduces the concept of 'ISM-Advanced', which incorporates Cognitive Radio capabilities into the rules for unlicensed spectrum access in ISM bands. It is argued and shown that the introduction of such capabilities can significantly improve the efficiency of spectrum usage, as well as the quality of service that is experienced by spectrum users. Moreover, constraints such as on transmission power can be relaxed under the proposed scheme, and the stability in performance of unlicensed spectrum can be improved. Among many other benefits, these characteristics facilitate use of unlicensed spectrum by quality-of-service-conscious telecommunication service entities such as cellular (LTE) operators, likely in aggregation with and supplementing their licensed spectrum. In view of the increased use and allocations being seen of unlicensed spectrum, it is suggested that the policies and technical rules that govern dynamic spectrum access in ISM bands be reviewed bringing them up to a level matching technical capabilities of modern radio equipment using Cognitive Radio technology. © 2014 IEEE.

Source title: 2014 IEEE International Symposium on Dynamic Spectrum Access Networks, DYSPAN 2014

DOI: 10.1109/DySPAN.2014.6817796

Link: ISM-Advanced: Improved access rules for unlicensed spectrum

Medeisis, A.; Sydor, J.; Cremene, L.C.; Holland, O.; Anskaitis, A.; Wiecek, D.; Haddad, Y.; Cuzanauskas, T.
Error propagation in the cancellation stage for a multi-layer signal reception

Year: 2014

Abstract: Cloud-Txn is a new broadcasting approach, which proposes the usage of the layer-division-multiplexing (LDM) to meet the requirements of the new generation digital TV services. Cloud Txn has been proposed as one of the candidate technologies for the Next Generation DTV systems. This technology is considered as an attractive alternative to the commonly used Time Division (TDM) and Frequency Division (FDM) multiplexing. Its main advantage lies in being more efficient as the RF channel is continuously used both in time and frequency, while the flexibility for each layer configuration is maintained. Nevertheless, the performance of this technique is closely related to the accuracy of the cancelation process required to decouple the multi-layered signals. The main objective of this paper is to analyze the possible error propagation due to the cancellation stage and the corresponding impact on the layers performance. © 2014 IEEE.

Source title: IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, BMSB

DOI: 10.1109/BMSB.2014.6873554

Link: Error propagation in the cancellation stage for a multi-layer signal reception

Montalban, J.; Angulo, I.; Velez, M.; Angueira, P.; Regueiro, C.; Wu, Y.; Zhang, L.; Li, W.
Large size FFTs over time-varying channels

Year: 2014

Abstract: In orthogonal frequency division multiplexing (OFDM) signals, the usage of large size fast Fourier transforms (FFTs) reduces the guard interval percentage, and therefore increases the data throughput reducing the data overhead. In addition, for the same pilot pattern, the distance between adjacent pilots is smaller, which will improve the channel estimation. Nevertheless, up to now, they have not been considered for delivering mobile services as the inter-carrier interference (ICI) due to the Doppler effect is very critical. The main objective is to show that taking advantage of the latest improvements in error correction techniques, it is feasible to use large size FFTs for time-varying channels. Furthermore, there is also presented a theoretical estimation for quantifying the loss due to the ICI, and finally several simulation results that reinforce the idea that large OFDM symbols are suitable for mobile channels. © 2014 The Institution of Engineering and Technology.

Source title: Electronics Letters

Series Number: Volume 50 Issue 15

DOI: 10.1049/el.2014.1301

Link: Large size FFTs over time-varying channels

Montalban, J.; Velez, M.; Angulo, I.; Angueira, P.; Wu, Y.
Cloud transmission: System performance and application scenarios

Year: 2014

Abstract: Cloud transmission (Cloud Txn) is a flexible multilayer system that uses spectrum overlay technology to simultaneously deliver multiple program streams with different characteristics and robustness for different services (mobile TV, HDTV, and UHDTV) in one radio frequency channel. Cloud Txn is a multilayer transmission system like layered-division multiplexing. The transmitted signal is formed by superimposing a number of independent signals at desired power levels to form a multilayered signal. The signals of different layers can have different coding, bit rate, and robustness. The upper layer system parameters are chosen to provide very robust transmission that can be used for high-speed mobile broadcasting. The bit rate is traded for powerful coding and robustness so that the signal-to-noise ratio (SNR) threshold at the receiver is in the range of -2 to -3 dB. The top layer is designed to withstand combined noise, co-channel interference and multipath distortion power levels higher than the desired signal power. The lower-layer signal can be a DVB-T2 signal or another new system to deliver HDTV/UHDTV to fixed receivers. The system concept is open to technological advances that might come in the future: BICM/non uniform-QAM, rotated constellations, time frequency slicing or MIMO techniques can be implemented in the Cloud Txn lower (high data rate) layer. The system can have backward compatible future extensions, adding more lower layers for additional services without impact legacy services. This paper describes the performance of Cloud Txn broadcasting system. © 1963-12012 IEEE.

Source title: IEEE Transactions on Broadcasting

Series Number: Volume 60 Issue 2

DOI: 10.1109/TBC.2014.2304153

Link: Cloud transmission: System performance and application scenarios

Montalban, J.; Zhang, L.; Gil, U.; Wu, Y.; Angulo, I.; Salehian, K.; Park, S.-I.; Rong, B.; Li, W.; Kim, H.M.; Angueira, P.; Velez, M.
Joint network channel fountain scheme for reliable communication in wireless networks

Year: 2014

Abstract: Joint network-channel coding (JNCC) has attracted significant interest recently for reliable data transmission over error-prone transmission channel. However, it appears that no fixed-rate channel coding is capable of driving the outage probability to zero without channel state information at the transmitter. In this paper we employ rateless coding and network coding for reliable communication in wireless relay networks. Specially we develop a scheme of joint network and fountain coding (JNFC), which can effectively combat the detrimental effect of wireless fading channel by seamlessly coupling fountain and network paradigms. Simulation results justify that our proposed JNFC has significant performance advantage over other schemes in a variety of metrics. © 2014 IEEE.

Source title: 2014 International Conference on Computing, Networking and Communications, ICNC 2014

DOI: 10.1109/ICCNC.2014.6785332

Link: Joint network channel fountain scheme for reliable communication in wireless networks

Nessa, A.; Kadoch, M.; Rong, B.
Efficient and reliable communication in wireless relay networks using joint network channel fountain

Year: 2014

Abstract: In the past few years, joint network-channel coding (JNCC) has drawn significant attention for reliable data communication in wireless network. However, it appears that fixed-rate channel coding is ineffective to make the outage probability to zero without having precise channel state information at the transmitter. To enhance the link robustness and the system throughput, this paper presents a joint network-fountain coding (JNFC) scheme which can effectively combat the detrimental effect of wireless fading channel by seamlessly coupling fountain and network paradigms. In particular, we consider a cooperative system with two sources, two relays and one destination where the sources encode the message using fountain code and broadcast to the destination and relays. While the relays first decode the information and then transmit to the destination after network and fountain coding. For information combining at relays we employ Random Linear Network Coding (RLNC) and Modified LT coding (MLT). Simulation results justify that JNFC has significant performance advantage over other schemes and JNFC with Modified LT coding (JNFC-MLT) always outperforms JNFC with Random Linear Network Coding (JNFC-RLNC) in a variety of metrics regardless of network scenarios. © 2014 Engineering and Technology Publishing.

Source title: Journal of Communications

Series Number: Volume 9 Issue 8

DOI: 10.12720/jcm.9.8.597-606

Link: Efficient and reliable communication in wireless relay networks using joint network channel fountain

Nessa,A.; Kadoch, M.; Rong, B.
Connectivity in mobile tactical networks

Year: 2014

Abstract: In today's network-centric battlefield, the ad hoc style, self-organizing networks play a more and more important role in the operation of mobile forces that are deployed quickly to meet the tactical demands. However, the unique features of the tactical scenario also pose significant challenges for networking, which makes the existing research results for the general mobile ad hoc networks (MANETs) difficult to be reused directly. In this paper, we focus on the connectivity issue of the mobile tactical networks (MTNs). To better describe the special formation-oriented mobility pattern of MTNs, a more realistic node-following mobility model is used, based on which the neighbor connectivity is obtained from both the geometrical and physical communication point of view for not only 1-D but also 2-D network scenarios. After that, we further evolve our recently proposed decomposition and recursion method to derive the end-to-end connectivity for some formations commonly used in the MTNs. All our analytical results are verified by extensive simulations. We believe that this work is able to shed new lights on the MTNs' performance characteristics, which can be used for guiding the development of the next-generation MTNs. © 2014 IEEE.

Source title: 2014 IEEE Global Communications Conference, GLOBECOM 2014

DOI: 10.1109/GLOCOM.2014.7037500

Link: Connectivity in mobile tactical networks

Ni, M.; Zhang, L.; Pan, J.; Cai, L.; Rutagemwa, H.; Li, L.; Wei, T.
POXN: A new passive optical cross-connection network for low-cost power-efficient datacenters

Year: 2014

Abstract: Passive optical devices, characterized by low cost, zero energy consumption, and high reliability, are essential building blocks for today's telecom network infrastructure, permeating from conventional backbone transport networks towards next-generation broadband access networks. Motivated by the striking features of passive optical devices, in this paper, we seek their potential applications in emerging datacenter networks to tackle the scalability challenges arising from cost and power. Specifically, we propose passive optical cross-connection networks (POXNs) that enable cost-saving, power-efficient, and reliable communication within datacenters. To support POXNs in warehouse-scale datacenters, we address physical-layer scalability challenges by using advanced interconnection techniques. Next, we propose a distributed polling protocol to address link-layer issues that arise from the broadcast nature of the medium. The performance of our protocol is studied through analysis and simulation. In particular, we develop an analytical model to compute lower and upper bounds on the expected delay of a packet. Numerical results show that the mean packet delay is equal to the lower bound in one regime, while converges to the upper bound in the complementary regime. Results also show that our protocol can achieve high bandwidth efficiency (no less than 85% in our studied case). Additionally, we demonstrate that our protocol can embrace scheduling algorithms that support fairness and QoS. Last, we sketch the roles POXNs can play in various datacenter network architectures in terms of capital and operational cost reductions. © 2014 IEEE.

Source title: Journal of Lightwave Technology

Series Number: Volume 32 Issue 8

DOI: 10.1109/JLT.2013.2295599

Link: POXN: A new passive optical cross-connection network for low-cost power-efficient datacenters

Ni, W.; Huang, C.; Liu, Y.L.; Li, W.; Leong, K.-W.; Wu, J.
Provisioning high-availability datacenter networks for full bandwidth communication

Year: 2014

Abstract: One critical challenge in datacenter network design is full bandwidth communication. Recent advances have enabled this communication paradigm based on the notion of Valiant load balancing (VLB). In this paper, we target full bandwidth communication among all servers, for all valid traffic patterns, and under k arbitrary link failures. We focus on two typical datacenter topologies, VL2 and fat-tree, and propose a mechanism to perform VLB on fat-tree. We develop the minimum link capacity required on both topologies, where edge and core links are handled separately. These results can help datacenter providers to provision their networks with guaranteed availability. Based on the results, we evaluate the minimum total link capacity required on each topology and characterize the capacity increase trend with k and with the total number of supported servers. These studies are important for datacenter providers to project their capital expenditures on datacenter design, upgrade, and expansion. Next, we compare the total link capacity between the two topologies. We find that given the same server scale, fat-tree requires less total capacity than does VL2 for small k. For large k, there exists a turning point at which VL2 becomes more capacity-efficient. © 2014 American Geophysical Union All Rights Reserved.

Source title: Computer Networks

Series Number: Volume 68

DOI: 10.1016/j.comnet.2013.12.006

Link: Provisioning high-availability datacenter networks for full bandwidth communication NOTE: A login may be required to access this site.

Ni, W.; Huang, C.; Wu, J.
Integrated design of fault localization and survivable mapping in IP over transparent WDM networks

Year: 2014

Abstract: Lightpaths play multiple critical roles in cross-layer fault management of IP over transparent optical networks. While the roles of lightpaths have been discussed specifically in fault localization as well as fault recovery phases, these existing works only take a sporadic, piecemeal view of these roles by studying each of them individually as a separate lightpath routing problem. In this paper, we instead take an integrated, systematic view by considering these multiple roles jointly as one single lightpath routing problem. In particular, we propose a new design model to fulfill the lightpath layout requirements in both identifying fiber link failures for fault localization and ensuring IP topology connectivity for fault recovery. With a much smaller formulation size, our new model significantly outperforms the existing counterpart in computational efficiency, scalability, and solution quality. © 2014, Springer Science+Business Media New York.

Source title: Photonic Network Communications

Series Number: Volume 28 Issue 3

DOI: 10.1007/s11107-014-0452-4

Link: Integrated design of fault localization and survivable mapping in IP over transparent WDM networks

Ni, W.; Huang, C.; Wu, J.
Reflectarray antennas using single layer polarization independent multi-resonant unit cells

Year: 2014

Abstract: The investigation results of a single layer reflectarray (RA) antenna are presented and discussed. The design frequency of the RA is set at 12 GHz, and it consists of 20 × 20 polarization independent resonant unit cells (UCs), which are illuminated by a circular horn antenna placed at F=200 mm to obtain F/D=0.77. The UCs are composed of three resonant elements, a cross loop surrounded by two concentric circular rings. The obtained results demonstrate that the proposed new UC provides a large linear phase variation range of at least 700°. The designed RA antenna offers a gain of at least 27.5 dB for an aperture area of 10Λ × 10λ at the operating frequency. © 2014 IEEE.

Source title: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest)

DOI: 10.1109/APS.2014.6904731

Link: Reflectarray antennas using single layer polarization independent multi-resonant unit cells

Niroo-Jazi, M.; Chaharmir, M.R.; Shaker, J.; Sebak, A.R.
A hybrid isolator to reduce electromagnetic interactions between Tx/Rx antennas

Year: 2014

Abstract: A hybrid compact isolator with a cross section of 17 × 11 mm 2 is proposed to reduce the electromagnetic coupling between two vertically polarized Tx/Rx microstrip antennas, both operating at 9.4 GHz. This isolator is built by embedding a piece of artificial material between two metallic walls. The obtained results using this hybrid isolator demonstrate that the coupling between the two antennas is significantly reduced across at least 55% of the matching band. To substantiate the proposed configuration, a prototype is fabricated and tested, and the corresponding measured results are presented. Furthermore, the discrepancies between the simulations and measurements are interpreted with the aid of the electromagnetic (EM) simulator. © 2013 IEEE.

Source title: IEEE Antennas and Wireless Propagation Letters

Series Number: Volume 13

DOI: 10.1109/LAWP.2013.2296139

Link: A hybrid isolator to reduce electromagnetic interactions between Tx/Rx antennas

Niroo-Jazi, M.; Denidni, T.A.; Chaharmir, M.R.; Sebak, A.R.
Meta-surfaces and antennas' radiation characteristics enhancement: Planar microstrip and microstrip-based quasi-aperture antennas

Year: 2014

Abstract: Meta-surfaces as artificial magnetic conductors or high impedance surfaces to control the electromagnetic fields excited by a microstrip patch resonator are investigated for planar and non-planar structures. In the planar structure, two types of meta-surfaces are used as electromagnetic transducers to transform the captured non-radiating waves to radiated space waves, leading to about 4 dBi gain enhancement. Alternatively, by applying these surfaces as E-plane fences in two sides of a patch, a compact microstrip-based quasiaperture antenna is proposed. The proposed antenna not only improves the gain up to 8 dBi, but also provides almost a symmetric radiation pattern by controlling the phase distribution of electric fields in the antenna aperture. Using near electric-field pattern inspection and characterising the meta-surfaces, the radiation mechanism of the proposed antennas are delineated. Two antenna prototypes are fabricated and tested and, confirming the simulated ones, the corresponding measured results are presented. © The Institution of Engineering and Technology 2014.

Source title: IET Microwaves, Antennas and Propagation

Series Number: Volume 8 issue 12

DOI: 10.1049/iet-map.2014.0117

Link: Meta-surfaces and antennas' radiation characteristics enhancement: Planar microstrip and microstrip-based quasi-aperture antennas

Niroo-Jazi, M.; Denidni, T.A.; Chaharmir, M.R.; Sebak, A.R.
Applications of polarization-independent frequency selective filters for transmitarray antennas

Year: 2014

Abstract: Polarization-insensitive band-stop and band-pass filters are investigated for transmitarray (TA) antennas. Their performances in terms of phase variation and transmission loss for different TE-incident angles are presented and discussed. As a proof of concept, a TA with an aperture area of 7λ × 7λ is designed for the operating frequency 12 GHz. The results demonstrate at least 19 dB gain for this TA when it is illuminated by a horn placed at a focal distance of F=60 mm (i.e., F/D=0.3). © 2014 IEEE.

Source title: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest)

DOI: 10.1109/APS.2014.6904855

Link: Applications of polarization-independent frequency selective filters for transmitarray antennas

Niroo-Jazi, M.; Sebak, A.R.; Chaharmir, M.R.; Shaker, J.
Inter-domain routing for tactical mobile Ad-hoc networks

Year: 2014

Abstract: We propose and evaluate a routing solution for a large scale tactical inter-domain network containing multiple Mobile Ad-hoc Networks (MANETs) and fixed networks. The proposed solution uses Open Shortest Path First-MANET Designated Router (OSPF-MDR); which is a modification of OSPFv3 to support MANETs as well as OSPFv3 in the fixed networks. We then propose a new border gateway routing protocol which supports the dynamic split and merger of MANETs, having routing abilities similar to the Border Gateway Protocol (BGP). This new protocol, named BGP-MANET Routing (BGP-MR)m, provides effective communication across separate and highly dynamic domains. BGP-MR introduces a dynamic election of gateways and recursive purging of routes from the BGP table as BGP peers are lost due to network mobility. The proposed solution is tested in CORE to show BGP-MR's effectiveness as a gateway protocol in mobile scenarios. Our results demonstrate BGP-MR's ability to provide seamless routing as well as reduced overhead when compared to running BGP in interconnecting highly dynamic MANETs. © 2014 IEEE.

Source title: IEEE Vehicular Technology Conference

DOI: 10.1109/VTCFall.2014.6966013

Link: Inter-domain routing for tactical mobile Ad-hoc networks

Okundaye, I.; Kunz, T.; Gulder, S.
On multihop communications for in-vehicle Internet access based on a TDMA MAC protocol

Year: 2014

Abstract: A vehicular ad hoc network (VANET) is an emerging technology which has a great potential in realizing a variety of new applications. This paper presents a new packet routing scheme which allows a vehicle to discover the existence of a gateway to the Internet and to send/receive packets to/from the gateway via multihop communications. The proposed routing scheme is based on a multichannel medium access control protocol, known as VeMAC [1], [2], using time division multiple access. The performance of this cross-layer design is evaluated for a multichannel VANET in terms of the end-to-end packet delay and the percentage of occupied time slots per frame in a highway scenario. Both packet queueing and service delays are considered in the end-to-end delay calculation by modeling each relay vehicle as a queueing system, in which the packets are served in batches of no more than a specified maximum batch-size. © 2014 IEEE.

Source title: Proceedings - IEEE INFOCOM

DOI: 10.1109/INFOCOM.2014.6848115

Link: On multihop communications for in-vehicle Internet access based on a TDMA MAC protocol

Omar, H.A.; Zhuang, W.; Li, L.
Photosintering and electrical performance of CuO nanoparticle inks

Year: 2014

Abstract: A copper oxide (CuO) nanopPublished Paper/Article ink was inkjet printed and photosintered in order to optimize electrical performance as a function of pattern dimension. For a given photosintering condition, electrical conductance varied strongly with line widths, ranging from 100 to 300 µm, illustrating the implications of printing and sintering complex circuit designs with varying feature sizes. By tuning the time delay between printing and sintering, exposure wavelength, radiant energy, pulse width and the distance between the light-source and substrate, photosintering conditions were optimized so that variations in sheet resistance for different line widths were minimized. Using optimized photosintering conditions, a sheet resistance value as low as 150 mΩ/ (resistivity of 9 µΩ cm) and current carrying capacity of 280 mA for a 300 µm wide trace was achieved. © 2014 Published by Elsevier B.V. All rights reserved.

Source title: Organic Electronics: physics, materials, applications

Series Number: Volume 15 Issue 8

DOI: 10.1016/j.orgel.2014.05.014

Link: Photosintering and electrical performance of CuO nanoparticle inks NOTE: A login may be required to access this site.

Paquet, C.; James, R.; Kell, A.J.; Mozenson, O.; Ferrigno, J.; Lafreniere, S.; Malenfant, P.R.L.
Field test results of additional data transmission for the ATSC terrestrial DTV system

Year: 2014

Abstract: In this paper, we explain an additional data transmission (ADT) increasing the data capacity of the advanced television systems committee terrestrial digital television (DTV) system, present its field test results conducted in Jeju Island, Korea, and analyze the results in different scenarios. The ADT system can offer an additional data of rate from a few hundred bits per second (bps) to a few megabits per second based on a transmitter identification (TxID) or successive interference cancellation (SIC) techniques. For the field test, the field strength and the required carrier to noise ratio for a stable reception were measured at each test point. Based on the field test, we verify that the TxID- and SIC-based ADT systems can provide an additional data link supporting 160 bps data rate, which is at least 13 dB robust compared to the conventional DTV system, and 2 Mbps data rate which is about 3 dB worse than the conventional DTV system, respectively. © 2014 IEEE.

Source title: IEEE Transactions on Broadcasting

Series Number: Volume 60 Issue 4

DOI: 10.1109/TBC.2014.2348892

Link: Field test results of additional data transmission for the ATSC terrestrial DTV system

Park, S.I.; Kim, H.M.; Wu, Y.; Kim, J.
Raptor-like rate compatible LDPC codes and their puncturing performance for the cloud transmission system

Year: 2014

Abstract: This paper proposes a class of raptor-like rate compatible low-density parity check (LDPC) codes for the cloud transmission (CTxN) system. The proposed LDPC codes have lengths of 16,200 and 64,800 which are the same as those of DVB T2/S2 LDPC codes so that the CTxn system can easily be combined with the DVB-T2/S2 system for a second layer service. As the proposed LDPC codes are optimized at low coding rate range (R<1/2) , their performance is not only close to the Shannon limit, but also better than the DVB-T2/S2 LDPC codes. Moreover, the proposed LDPC codes have raptor code's property so that they can be decoded with a punctured codeword at the receiver for power saving and less latency under high signal-to-noise ratio regions. © 1963-12012 IEEE.

Source title: IEEE Transactions on Broadcasting

Series Number: Volume 60 Issue 2

DOI: 10.1109/TBC.2014.2304134

Link: Raptor-like rate compatible LDPC codes and their puncturing performance for the cloud transmission system

Park, S.I.; Wu, Y.; Kim, H.M.; Hur, N.; Kim, J.
LDPC-RS two dimensional code for the next generation cloud transmission system

Year: 2014

Abstract: This paper proposes a two dimensional (2D) code, which has vertical raptor-like rate-compatible LDPC code and horizontal Reed Solomon (RS) code, for the terrestrial CTxn system. The proposed 2D code not only removes error-floor phenomenon with a help of RS code, but also does not require a complex interleaver for stable reception under fading channels because the 2D code itself provides block-type interleaver. © 2014 IEEE.

Source title: IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, BMSB

DOI: 10.1109/BMSB.2014.6873509

Link: LDPC-RS two dimensional code for the next generation cloud transmission system

Park, S.I.; Wu, Y.; Kim, H.M.; Kwon, S.; Zhang, L.; Rong, B.; Hur, N.; Kim, J.
QoE aware resource allocation for video communications over LTE based mobile networks

Year: 2014

Abstract: As the limits of video compression and usable wireless radio resources are exhausted, providing increased protection to critical data is regarded as a way forward to increase the effective capacity for delivering video data. This paper explores the provisioning of selective protection in the physical layer to critical video data and evaluates its effectiveness when transmitted through a wireless multipath fading channel. In this paper, the transmission of HEVC encoded video through an LTE-A wireless channel is considered. HEVC encoded video data is ranked based on how often each area of the picture is referenced by subsequent frames within a GOP in the sequence. The critical video data is allotted to the most robust OFDM resource blocks (RBs), which are the radio resources in the time-frequency domain of the LTE-A physical layer, to provide superior protection. The RBs are ranked based on a prediction for their robustness against noise. Simulation results show that the proposed content aware resource allocation scheme helps to improve the objective video quality up to 37dB at lower channel SNR levels when compared against the reference system, which treats video data uniformly. Alternatively, with the proposed technique the transmitted signal power can be lowered by 30% without sacrificing video quality at the receiver. © 2014 ICST.

Source title: Proceedings of the 2014 10th International Conference on Heterogeneous Networking for Quality, Reliability, Security and Robustness, QSHINE 2014

DOI: 10.1109/QSHINE.2014.6928661

Link: QoE aware resource allocation for video communications over LTE based mobile networks

Perera, R.; Fernando, A.; Mallikarachchi, T.; Arachchi, H.K.; Pourazad, M.
Performance Evaluation of Next Generation Wi-Fi (802.11ac) for Mobile Offloading

Year: 2014

Abstract: This paper provides performance evaluation of commercial off-the-shelf (COTS) next-generation Wi-Fi devices (802.11ac) in a controlled laboratory environment.

Source title: IEEE 11th Annual Consumer Communications and Networking Conference (CCNC 2014)

DOI: 10.1109/CCNC.2014.6940508

Link: Performance Evaluation of Next Generation Wi-Fi (802.11ac) for Mobile Offloading

Picard, V.; Lafond, E.
Modeling and process control of MOCVD growth of InAlGaAs MQW structures on InP

Year: 2014

Abstract: We have developed a model which integrates calculation of InAlGaAs multiple quantum well (MQW) transition energies using the envelope function approximation with a statistical analysis of the PL emission wavelength, net strain and MQW period measured for a variety of MQW designs grown by MOCVD. The model relates the measured MQW parameters directly to MOCVD process parameters, allowing an accurate prediction of the process parameters required to grow a specified MQW design. This greatly reduces the need to grow and characterize individual calibration layers. The difference of the measured and predicted MQW parameters is recorded run-to-run over time, which allows process variability to be analyzed across a number of process parameters with intentional variations to grow different MQW designs. © 2013 Elsevier B.V.

Source title: Journal of Crystal Growth

Series Number: Volume 393

DOI: 10.1016/j.jcrysgro.2013.10.019

Link: Modeling and process control of MOCVD growth of InAlGaAs MQW structures on InP NOTE: A login may be required to access this site.

Pitts, O.J.; Benyon, W.; Springthorpe, A.J.
Optimization of MOCVD-diffused p-InP for planar avalanche photodiodes

Year: 2014

Abstract: We investigate the materials properties and dark currents of planar InP/InGaAs avalanche photodiodes (APDs) in which the p-dopant, Zn, is introduced by diffusion in an MOCVD reactor using dimethylzinc (DMZn) as the source. APD dark currents are compared with low-temperature photoluminescence (PL), electrochemical capacitance-voltage (ECV) and secondary ion mass spectroscopy (SIMS) measurements of layers diffused under the same set of conditions. Device dark currents exhibit both surface-related and bulk contributions, with the bulk contribution appearing as a step increase in the current near the punch-through voltage. The bulk dark current contribution depends on the diffusion process parameters and is correlated with the total Zn incorporation and the intensities of the InP and InGaAs PL peaks. A variation of three orders of magnitude is observed in the bulk dark current contribution as diffusion conditions are varied. © 2013 Elsevier B.V.

Source title: Journal of Crystal Growth

Series Number: Volume 393

DOI: 10.1016/j.jcrysgro.2013.09.053

Link: Optimization of MOCVD-diffused p-InP for planar avalanche photodiodes NOTE: A login may be required to access this site.

Pitts, O.J.; Hisko, M.; Benyon, W.; Raymond, S.; Springthorpe, A.J.
Cognitive radio based adaptive SON for LTE-A heterogeneous networks

Year: 2014

Abstract: This paper presents a novel scheme of adaptive self-organization network (SON) by integrating cognitive radio (CR) with inter-cell interference coordination (ICIC) for LTE-A heterogeneous networks (HetNets). Particularly, we take advantage of the spectrum sensing function from CR and the radio resource layering function from ICIC. Our work addresses the issues of smart low-power node (SLPN) development, which associates appropriate sectorization with radio resource allocation during the self-organization process. We further develop a Hungary algorithm based self-organization strategy to improve the SLPN adaptive optimization. Simulation results show that our proposed scheme can achieve considerable gain in terms of throughput and coverage, with extra rewards of high flexibility and low complexity in HetNet SON. © 2014 IEEE.

Source title: 2014 IEEE Global Communications Conference, GLOBECOM 2014

DOI: 10.1109/GLOCOM.2014.7037502

Link: Cognitive radio based adaptive SON for LTE-A heterogeneous networks

Qi, F.; Sun, S.; Rong, B.; Hu, R.Q.; Qian, Y.
Wideband Printed Bowtie Array for Spectrum Monitoring

Year: 2014

Abstract: A six-element compact array of wideband printed bowtie antennas is designed for mobile spectrum monitoring applications covering 2-6 GHz. Each element in the array is designed to cover a 60° azimuth sector with minimal beam-width variation over the frequency band. Simulated beam patterns and return loss performance is provided. © 2014 IEEE.

Source title: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest)

DOI: 10.1109/APS.2014.6904449

Link: Wideband Printed Bowtie Array for Spectrum Monitoring

Raut, S.; Petosa, A.
High-power X-band GaN switched-filter phase shifter

Year: 2014

Abstract: This paper presents a high-power switched-filter GaN phase shifter, designed for X-band and offering good performance from 8-16 GHz. The manufactured 0°/22.5° switched-filter phase shifter has much wider bandwidth than is typically found with this configuration, while maintaining low insertion loss (< 2 dB), good return loss (> 11.15 dB) and an amplitude imbalance of less than 1.03 dB across X-band. The 1 dB compression point was higher than laboratory equipment was able to measure (> 38 dBm) and the phase shifter MMIC exhibited an IIP3 higher than 46 dBm. The proposed high-power phase shifter has been fabricated in a 0.5 µm GaN HEMT process and was designed using an accurate, customized switch FET model. © 2014 IEEE.

Source title: IEEE MTT-S International Microwave Symposium Digest

DOI: 10.1109/MWSYM.2014.6848556

Link: High-power X-band GaN switched-filter phase shifter

Ross, T.N.; Cormier, G.; Hettak, K.; Wight, J.S.
Dual-band split-ring resonator using composite right-/left-handed coplanar waveguide transmission line-based elements

Year: 2014

Abstract: In this paper, a new dual-band split ring resonator based on frequency-controlled-response distributed elements is proposed. The response of the new inclusion is controlled using special composite right-/left-handed transmission line-based elements patterned in the centre strip of a folded coplanar waveguide line. These new reactive elements are deployed into a transmission line-based split ring resonator inclusion in order to have the dual-band resonance. The design procedure and theory behind the new inclusion is introduced. Simulated results agree well with the theoretical results. © 2014 IEEE.

Source title: Canadian Conference on Electrical and Computer Engineering

DOI: 10.1109/CCECE.2014.6901113

Link: Dual-band split-ring resonator using composite right-/left-handed coplanar waveguide transmission line-based elements

Safia, O.A.; Talbi, L.; Hettak, K.
Continuously tunable photonic fractional Hilbert transformer using a high-contrast germanium-doped silica-on-silicon microring resonator

Year: 2014

Abstract: We propose and experimentally demonstrate a continuously tunable fractional Hilbert transformer (FHT) based on a high-contrast germanium-doped silica-on-silicon (SOS) microring resonator (MRR). The propagation loss of a highcontrast germanium-doped SOS waveguide can be very small (0.02 dB/cm) while the lossless bend radius can be less than 1 mm. These characteristics lead to the fabrication of an MRR with a high Q-factor and a large free-spectral range (FSR), which is needed to implement a Hilbert transformer (HT). The SOS MRR is strongly polarization dependent. By changing the polarization direction of the input signal, the phase shift introduced at the center of the resonance spectrum is changed. The tunable phase shift at the resonance wavelength can be used to implement a tunable FHT. A germanium-doped SOS MRR with a high-index contrast of 3.8% is fabricated. The use of the fabricated MRR for the implementation of a tunable FHT with tunable orders at 1, 0.85, 0.95, 1.05, and 1.13 for a Gaussian pulse with the temporal full width at half-maximum of 80 ps is experimentally demonstrated. © 2014 Optical Society of America.

Source title: Optics Letters

Series Number: Volume 39 Issue 9

DOI: 10.1364/OL.39.002778

Link: Continuously tunable photonic fractional Hilbert transformer using a high-contrast germanium-doped silica-on-silicon microring resonator

Shahoei, H.; Dumais, P.; Yao, J.
A novel bidirectional antenna with broadband circularly polarized radiation in X-Band

Year: 2014

Abstract: A novel bidirectional antenna with a broadband circular polarization (CP) property in X-band is proposed. The CP characteristics are simply achieved by the asymmetrical Y-shaped feeding line. Both the impedance bandwidth and the axial-ratio (AR) bandwidth can be greatly improved by a through-via that is in series with an inductive strip and the polygon slot structure. The antenna is fabricated and measured for verifying the theory. A good agreement is achieved between the simulated and measured results. The 10-dB return-loss bandwidth is 31.4%, in which the AR is less than 2 dB. The measured radiation pattern shows a near-symmetry bidirectional radiation with the peak gain of 4.6 dBi. This antenna is a good candidate as a unit element in beamforming array applications. © 2002-2011 IEEE.

Source title: IEEE Antennas and Wireless Propagation Letters

Series Number: Volume 13

DOI: 10.1109/LAWP.2013.2295151

Link: A novel bidirectional antenna with broadband circularly polarized radiation in X-Band

Shen, J.; Lu, C.; Cao, W.; Yang, J.; Li, M.
Visual comfort amelioration technique for stereoscopic images: Disparity remapping to mitigate global and local discomfort causes

Year: 2014

Abstract: This paper proposes a new disparity remapping framework to improve the visual comfort of stereoscopic images. The proposed framework adaptively remaps disparities of a scene according to different causes of visual discomfort. A linear disparity remapping is first performed in order to address visual discomfort induced by excessive disparities. This linear remapping changes the disparities of the scene to obtain an overall target disparity range. Then, a nonlinear disparity remapping process selectively adjusts the disparity of problematic local disparity ranges according to their contribution to the visual discomfort. The proposed nonlinear disparity remapping process enables us to minimize the loss in perceived depth range while further improving visual comfort. The effectiveness of the proposed disparity remapping framework has been successfully evaluated by subjective assessments of visual comfort and naturalness. Experimental results demonstrate the validity of the proposed remapping framework. More importantly, we show that the nonlinear refinement of disparity in problematic regions can efficiently improve visual comfort while maintaining the naturalness of the scene. © 2013 IEEE.

Source title: IEEE Transactions on Circuits and Systems for Video Technology

Series Number: Volume 24 Issue 5

DOI: 10.1109/TCSVT.2013.2291281

Link: Visual comfort amelioration technique for stereoscopic images: Disparity remapping to mitigate global and local discomfort causes

Sohn, H.; Jung, Y.J.; Lee, S.-I.; Speranza, F.; Ro, Y.M.
A survey of two kinds of complementary coded CDMA wireless communications

Year: 2014

Abstract: In this Published Paper/Article, we present a comprehensive survey of existing literature in the area of complementary coded CDMA (CC-CDMA) technique for wireless communications to provide an introduction and overview to the field. According to the kinds of independent sub-channels, we divide the existing CC-CDMA solutions into two categories: time division multiplex (TDM) and frequency division multiplex (FDM) CC-CDMA systems. Then we compared them in terms of resistance of multiuser interference and multi-path interference, implementation complexity and spread and spectrum efficiency. © 2014 IEEE.

Source title: 2014 IEEE Global Communications Conference, GLOBECOM 2014

DOI: 10.1109/GLOCOM.2014.7036852

Link: A survey of two kinds of complementary coded CDMA wireless communications

Sun, S.; Han, S.; Yu, Q.; Meng, W.; Li, C.
Broadband 60 GHz sounder for propagation channel measurements over short/medium distances

Year: 2014

Abstract: This paper presents a millimeter-wave propagation-channel sounder that uses an optical-fiber cable to achieve phase coherence between transmitting and receiving antennas using two modulated light waves in the vicinity of 1550 nm. In the described sounder, the optical-fiber cable approach permits a separation of up to almost 1000 m between the transmitter and receiver because of the low level of attenuation per unit length in a single-mode optical-fiber cable. The measurement system can sweep from 500 MHz below 60.1 GHz (59.6 GHz) to 500 MHz above 60.1 GHz (60.6 GHz) and proceed to 10 001 in-phase and in-quadrature propagation channel measurements in ~ 5 sec. Measurements of the frequency response of nonline-of-sight and line-of-sight indoor/outdoor propagation channels over medium (> 100 m) and short ranges can be performed for two or more different lateral receiving antenna positions for antenna diversity studies. © 2013 IEEE.

Source title: IEEE Transactions on Instrumentation and Measurement

Series Number: Volume 63 Issue 2

DOI: 10.1109/TIM.2013.2280487

Link: Broadband 60 GHz sounder for propagation channel measurements over short/medium distances

Talbi, L.; Lebel, J.
Joint channel assignment and power allocation in cognitive radio networks

Year: 2014

Abstract: A joint channel assignment and power allocation algorithm is presented for cognitive wireless networks, where primary and secondary users operate over the same frequency band at the same time. In this study, we take into consideration a constraint on the interference from secondary users towards primary users, as well as a constraint on the QoS of secondary users. The problem is formulated as a constrained utility maximization problem, for which we prove the existence and the uniqueness of the global optimum solution. Since the problem is NP-hard, we provide a novel heuristic algorithm that operates in two phases. Firstly, it admits all the incoming secondary users and allocates the available channels through a distributed and dynamic procedure, taking into account the interference constraint. Secondly, an iterative power control, which considers both constraints, is applied. In each iteration, a user removal algorithm is employed to reduce the number of admitted secondary users until a steady state is reached. The performance of the joint resource allocation algorithm is investigated in terms of the total number of admitted secondary users for several network parameters, such as the minimum QoS requirements and the interference constraint. © 2014 IEEE.

Source title: 2014 IEEE Global Communications Conference, GLOBECOM 2014

DOI: 10.1109/GLOCOM.2014.7036919

Link: Joint channel assignment and power allocation in cognitive radio networks

Tsiropoulos, G.I.; Dobre, O.A.; Ahmed, M.H.; Baddour, K.E.
Robust two-way cognitive relaying: Precoder designs under interference constraints and imperfect CSI

Year: 2014

Abstract: We present various robust precoder designs for two-way relaying in a cognitive radio network, where a pair of cognitive (or secondary) transceiver nodes communicate with each other assisted by a set of cognitive two-way relays. The secondary nodes share the spectrum with a licensed primary user (PU) node while keeping the interference to the PU below a specified threshold. The PU node and the cognitive transceivers employ single transmit/receive antennas whereas the secondary relay nodes employ multiple transmit/receive antennas. The proposed precoder designs ensure robust performance in the presence of errors in the channel state information (CSI). Such robust designs are of significant interest since in practice it is very difficult to obtain perfect CSI. We consider CSI errors with two different types of characterization and corresponding robust designs. First, we consider robust relay precoder designs that are applicable when CSI errors have known first and second moments. Next, we consider robust designs that are applicable when the CSI error can be characterized in terms of spherical uncertainty region. We show that the proposed designs can be reformulated as convex optimization problems that can be solved efficiently. Through numerical simulations and comparisons we illustrate the performance of the proposed designs. © 2002-2012 IEEE.

Source title: IEEE Transactions on Wireless Communications

Series Number: Volume 13 Issue 5

DOI: 10.1109/TWC.2014.031714.130082

Link: Robust two-way cognitive relaying: Precoder designs under interference constraints and imperfect CSI

Ubaidulla, P.; Aissa, S.
Stochastic network collection point (NCP) selection in mobile sensor networks with cooperative communications

Year: 2014

Abstract: In wireless sensor networks (WSNs) with mobile sinks, some stationary sensor nodes, known as network collection points (NCPs), can communicate with mobile sinks to collect sensed data. Most existing works on mobile WSNs assume that mobile sinks directly communicate with NCPs via point-to-point links. Consequently, recent advances in cooperative communications, which are more energy-efficient than traditional point-to-point communications, are largely ignored in mobile WSNs. In this paper, we present a novel stochastic NCP selection scheme using cooperative communications. In addition, most existing works assume perfect channel state information (CSI) knowledge, which may not be realistic in practice. We only assume inaccurate CSI in this paper. We formulate the problem as a stochastic multi-armed bandit system. This formulation facilitates the distributed architecture due to its 'indexibility' characteristic, which dramatically simplifies the computation and implementation of the proposed scheme. Simulation results are presented to show the effectiveness of the proposed scheme. © 2014 IEEE.

Source title: IWCMC 2014 - 10th International Wireless Communications and Mobile Computing Conference

DOI: 10.1109/IWCMC.2014.6906510

Link: Stochastic network collection point (NCP) selection in mobile sensor networks with cooperative communications

Wang, M.; Yu, F.R.; Lamont, L.; Zhao, N.
A design of integrated ultra-wideband/narrow band rectangular dielectric resonator antenna

Year: 2014

Abstract: An ultra-wideband (UWB) rectangular dielectric resonator antenna (DRA) integrated with a narrow-band (NB) DRA is presented. The proposed antenna consists of a UWB rectangular DRA excited by a bevel-shaped patch and a NB DRA excited by a strip. The simulated results demonstrate that the UWB antenna provides a 2:1 voltage standing wave ratio (VSWR) bandwidth for 2.5-12 GHz, integrated with a NB antenna. Moreover, the two ports have the same polarization, and two symmetrical short circuited strips are used to improve the isolation between the two ports. This can be a suitable candidate for applications in cognitive radio, where the UWB antenna can be used for spectrum sensing and the NB antenna for communication operation. © 2014 IEEE.

Source title: 2014 IEEE International Wireless Symposium, IWS 2014

DOI: 10.1109/IEEE-IWS.2014.6864187

Link: A design of integrated ultra-wideband/narrow band rectangular dielectric resonator antenna

Wang, Y.; Denidni, T.A.; Zeng, Q.; Wei, G.
Integrated ultrawideband/narrowband rectangular dielectric resonator antenna for cognitive radio

Year: 2014

Abstract: An integrated ultrawideband (UWB) and narrowband (NB) rectangular dielectric resonator antenna (DRA) is presented. The proposed antenna consists of a UWB rectangular DRA excited by a bevel-shaped patch and an NB DRA excited by a strip. The measured results demonstrate that the UWB and NB antenna provides a 2:1 voltage standing wave ratio (VSWR) bandwidth for 2.4-12 and 2.3-4.5 GHz, respectively, with the same polarization. Moreover, two symmetrical short-circuited strips are introduced to improve the isolation between the two ports. This can be a suitable candidate for applications in cognitive radio, where the UWB antenna can be used for spectrum sensing and the NB antenna for communication operation. © 2002-2011 IEEE.

Source title: IEEE Antennas and Wireless Propagation Letters

Series Number: Volume 13

DOI: 10.1109/LAWP.2014.2314480

Link: Integrated ultrawideband/narrowband rectangular dielectric resonator antenna for cognitive radio

Wang, Y.; Wang, N.; Denidni, T.A.; Zeng, Q.; Wei, G.
Band-notched UWB rectangular dielectric resonator antenna

Year: 2014

Abstract: A new ultra-wideband (UWB) rectangular dielectric resonator antenna (DRA) with band-stop performance is proposed. Two symmetrical short-circuited strips together with a slot etched in the feeding patch are introduced to form the notched band. The design principles of the proposed methods are described in detail. The measured result demonstrates that the proposed DRA achieves an UWB bandwidth from 3.6 to 12 GHz for a voltage standing wave ratio < 2 with a notched band from 5.1 to 6.0 GHz.

Source title: Electronics Letters

Series Number: Volume 50 Issue 7

DOI: 10.1049/el.2014.0188

Link: Band-notched UWB rectangular dielectric resonator antenna

Wang, Y.F.; Denidni, T.A.; Zeng, Q.S.; Wei, G.
Security enhancements for mobile ad hoc networks with trust management using uncertain reasoning

Year: 2014

Abstract: The distinctive features of mobile ad hoc networks (MANETs), including dynamic topology and open wireless medium, may lead to MANETs suffering from many security vulnerabilities. In this paper, using recent advances in uncertain reasoning that originated from the artificial intelligence community, we propose a unified trust management scheme that enhances the security in MANETs. In the proposed trust management scheme, the trust model has two components: trust from direct observation and trust from indirect observation. With direct observation from an observer node, the trust value is derived using Bayesian inference, which is a type of uncertain reasoning when the full probability model can be defined. On the other hand, with indirect observation, which is also called secondhand information that is obtained from neighbor nodes of the observer node, the trust value is derived using the Dempster-Shafer theory (DST), which is another type of uncertain reasoning when the proposition of interest can be derived by an indirect method. By combining these two components in the trust model, we can obtain more accurate trust values of the observed nodes in MANETs. We then evaluate our scheme under the scenario of MANET routing. Extensive simulation results show the effectiveness of the proposed scheme. Specifically, throughput and packet delivery ratio (PDR) can be improved significantly with slightly increased average end-to-end delay and overhead of messages. © 2014 IEEE.

Source title: IEEE Transactions on Vehicular Technology

Series Number: Volume 63 Issue 9

DOI: 10.1109/TVT.2014.2313865

Link: Security enhancements for mobile ad hoc networks with trust management using uncertain reasoning

Wei, Z.; Tang, H.; Yu, F.R.; Wang, M.; Mason, P.
Trust establishment with data fusion for secure routing in MANETs

Year: 2014

Abstract: Mobile Ad hoc NETworks (MANETs) are a promising communication technology for tactical environments and emergency response operations. However, the features of MANETs, including dynamic topology and open wireless medium, lead to many security vulnerabilities. Malicious nodes can drop or modify packets that are received from other nodes and diminish the reliability of networks. Therefore, secure routing in MANETs is an important area of research. In this paper, we propose a scheme that enhances routing security based on trust. In the proposed scheme, in order to improve the accuracy of trust values with indirect observations, we use Dempster-Shafer theory of evidence to fuse observers' opinions. Consequently, a more accurate trust value can be calculated from indirect observations. We then utilize the trust value to enhance the MANET routing protocol security. Simulation results are presented to demonstrate the effectiveness of the proposed scheme. © 2014 IEEE.

Source title: 2014 IEEE International Conference on Communications, ICC 2014

DOI: 10.1109/ICC.2014.6883396

Link: Trust establishment with data fusion for secure routing in MANETs

Wei, Z.; Tang, H.; Yu, F.R.; Wang, M.; Mason, P.
Optical Switching and Networking – Editorial

Year: 2014

Abstract: [No abstract available]

Source title: Optical Switching and Networking

Series Number: Volume 11 Part A

DOI: 10.1016/j.osn.2013.11.001

Link: Optical Switching and Networking – Editorial NOTE: A login may be required to access this site.

Wu, J.; Wosinska, L.; Mas Machuca, C.; Tzanakaki, A.; Hasegawa, H.
Optical networks control and management

Year: 2014

Abstract: [No abstract available]

Source title: Journal of Network and Systems Management

Series Number: Volume 22 Issue 3

DOI: 10.1007/s10922-014-9311-y

Link: Optical networks control and management

Wu, J.; Wosinska, L.; Shen, G.; Spadaro, S.
A fully integrated 1-4 GHz GaN Class J power amplifier

Year: 2014

Abstract: A non-switching mode Class J power amplifier (PA) is presented. Its output power capability is improved by driving the active device into the non-linear region to generate extra harmonics. The output matching circuit is also structured to filter out unwanted harmonics to let the PA retain high efficiency and high linearity concurrently. A GaN Hetero-junction Field Effect transistor has a low output capacitance. Therefore, combining with a reactive load, a relatively broadband resonance circuit at GHz frequencies is designed. A fully integrated Class J PA., which has an area of 1.8 × 1.3 mm., is realized with measured 12% overall efficiency at the 2 dB compression point (P2dB), 3 GHz bandwidth, and 20.3 dBm output referred 1 dB compression. © 2014 IEEE.

Source title: 2014 IEEE 15th Annual IEEE Wireless and Microwave Technology Conference, WAMICON 2014

DOI: 10.1109/WAMICON.2014.6857749

Link: A fully integrated 1-4 GHz GaN Class J power amplifier

Wu, T.; Plett, C.; Rogers, J.W.M.; Li, M.
Channel estimation algorithms for cooperative spectrum sensing in amplify-and-forward cooperative system

Year: 2014

Abstract: In amplify-and-forward (AF)-based cooperative spectrum sensing system, the bit-error-rate (BER) performance and detection probability will decrease because of the existence of channel estimation error. In this paper, the influence of channel estimation error on system performance is firstly deduced, and then, linear minimum mean-square error (LMMSE) channel estimation algorithm with filtering delay time-domain windowing (LMMSE-filtering-DTW) technique and modified singular value decomposition-based LMMSE algorithm are proposed to improve the channel estimation performance for code division multiple access system and orthogonal frequency division multiplexing system in AF cooperative scenario, respectively. Simulation results verify the effectiveness of the two proposed channel estimation algorithms in cooperative spectrum sensing, and when Eb/ N0 is bigger than 20dB, given the required false alarm probability smaller than 15%, the difference of detection probability between the channel obtained using the proposed channel estimation algorithms and the ideal channel is less than 2.5%, respectively. Copyright © 2012 John Wiley & Sons, Ltd.

Source title: Wireless Communications and Mobile Computing

Series Number: Volume 14 Issue 13

DOI: 10.1002/wcm.2307

Link: Channel estimation algorithms for cooperative spectrum sensing in amplify-and-forward cooperative system

Wu, X.-L.; Luo, M.; Liu, K.; Shen, Q.
Variable LLR scaling in min-sum decoding for irregular LDPC codes

Year: 2014

Abstract: Min-sum decoding is a low-complexity alternative to the so-called belief propagation and consists in simplification of the nonlinear operation on the log likelihood ratios (LLRs) in the check nodes. The resulting suboptimality may be tempered via appropriate scaling of the LLRs, e.g., the fixed optimal scaling in the normalized min-sum algorithm, and variable scaling algorithms gradually appearing in the literature. However, up to now, none of the papers studied variable scaling both as per iteration and as per different check node degree, due to the prohibitive complexity of multioptimization over space of too many parameters. In this paper, we propose a generalized mutual information (GMI) of LLRs as the criterion to search for the scaling factors for different check node degrees in every iteration in a 1-D thus low-complexity manner. This approach is first analyzed via density evolution, and in addition can be extended to practical LLRs based formulas via Monte Carlo tools to cope with the mismatch issue. Bit error rate simulation results on two low-density parity-check codes show that our proposed GMI metrics have a noticeable gain over the variable scaling schemes that appeared in the literature. © 2014 IEEE.

Source title: IEEE Transactions on Broadcasting

Series Number: Volume 60 Issue 4

DOI: 10.1109/TBC.2014.2364532

Link: Variable LLR scaling in min-sum decoding for irregular LDPC codes

Xu, Y.; Szczecinski, L.; Rong, B.; Labeau, F.; He, D.; Wu, Y.; Zhang, W.
Capacity of wireless ad hoc networks with digital beamforming antennas

Year: 2014

Abstract: A collision model for wireless ad hoc networks with digital beamforming antennas is proposed, and an analytic result for network capacity is provided.

Source title: The 56th CORS (Canadian Operational Research Society) Annual Conference, Ottawa, Ontario, Canada, May 2014

DOI: N/A

Link: Capacity of wireless ad hoc networks with digital beamforming antennas (PDF document)

Zhang, C.; Li, J.; Zhou, Y.; Zhao. Y.
A low-complexity robust OFDM receiver for fast fading channels

Year: 2014

Abstract: Orthogonal frequency division multiplexing (OFDM) receivers suffer significant performance degradation in time-varying fast fading channels because of the inter-carrier interference (ICI) induced by the Doppler effect. We previously proposed a novel iterative decision-directed channel estimation and ICI cancellation technique which can provide robust performance for mobile OFDM receivers moving at fast vehicle speed. The nutshell of the proposed technique is a channel estimator which is capable of estimating the ICI gains on each off-diagonal vector of the channel frequency response matrix of a doubly-selective fading channel, which corresponds to the ICI induced by the neighbor subcarrier symbol to current subcarrier. In this paper, we generalize the channel estimator and provide theoretical analysis on the achievable performance. As an application to digital video broadcasting terrestrial system, we provide intensive simulation results and detailed comparison on implementation complexity and performance with existing techniques to showcase the significance of the proposed technique in practical applications. © 1963-12012 IEEE.

Source title: IEEE Transactions on Broadcasting

Series Number: Volume 60 Issue 2

DOI: 10.1109/TBC.2014.2321681

Link: A low-complexity robust OFDM receiver for fast fading channels

Zhang, L.; Hong, Z.; Thibault, L.; Boudreau, R.; Wuieee, Y.
Application of DFT-based channel estimation for accurate signal cancellation in Cloud-Txn multi-layer broadcasting system

Year: 2014

Abstract: Cloud transmission (Cloud-Txn) with layer-division-multiplexing (LDM) was proposed as a candidate Physical Layer (PHY) technology for the next generation digital TV broadcasting system. In this paper, we investigate the performance of the upper-layer signal cancellation with DFT-based channel estimation techniques, due to their capability of providing near-optimal performance for challenging channels with long delay spread at low Signal to Noise Ratio (SNR). Both Pilot-Aided (PA) and Decision-Directed (DD) techniques are investigated and their performances are compared. The major issue with DFT-based techniques is the 'edge effect' for OFDM systems with Null spectrum on either side of the useful spectrum, which serves as guard band. A Cloud-Txn/LDM system usually requires very accurate channel estimation to achieve very low residual upper-layer signal after the cancellation. In this case, the 'edge effect' becomes a significant impairment. In this paper, we evaluate different data-padding methods to reduce the 'edge effect', which fill the Null spectrum with Virtual Pilots (VP). It is shown that, with proper data-padding technique, 30 to 40 dB signal cancellation can be achieved. © 2014 IEEE.

Source title: IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, BMSB

DOI: 10.1109/BMSB.2014.6873491

Link: Application of DFT-based channel estimation for accurate signal cancellation in Cloud-Txn multi-layer broadcasting system

Zhang, L.; Wu, Y.; Li, W.; Kim, H.M.; Park, S.-I.; Angueira, P.; Montalban, J.; Velez, M.
Channel capacity distribution of Layer-Division-Multiplexing system for next generation digital broadcasting transmission

Year: 2014

Abstract: Cloud transmission (Cloud-Txn) with Layer-Division-Multiplexing (LDM) was proposed as a candidate Physical Layer (PHY) technology for next generation digital TV broadcasting system. This paper presents a fundamental analysis on the channel capacity allocation among the different layers of a LDM-based transmission system. The analysis reveals that, for delivering fixed and mobile TV services in the same RF channel, by controlling the power allocation among the layers, the LDM-based system provides much better efficient usage of the spectrum as compared to the single-layer Time-Division-Multiplexing (TDM) or Frequency-Division-Multiplexing (FDM)-based systems. The spectrum efficiency of LDM allows the simultaneous delivery of a high-data-rate UHDTV service and a mobile HDTV service within a single 6 MHz channel. © 2014 IEEE.

Source title: IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, BMSB

DOI: 10.1109/BMSB.2014.6873500

Link: Channel capacity distribution of Layer-Division-Multiplexing system for next generation digital broadcasting transmission

Zhang, L.; Wu, Y.; Li, W.; Kim, H.M.; Park, S.-I.; Angueira, P.; Montalban, J.; Velez, M.
FOBTV: Worldwide efforts in developing next-generation broadcasting system

Year: 2014

Abstract: The challenges facing the terrestrial broadcast industry are to how more efficiently and effectively use the scarce spectrum to deliver the vast amount of media data to the general public. Future of Broadcast Television Initiative (FOBTV) was founded by the broadcasters, manufacturers, network operators, standardization organizations, research institutes, and universities around the world, aiming at better solving these problems through global collaboration. Since its establishment, use cases for the future broadcast applications have been extensively collected and classified. Potential technologies applied for the summarized new application scenarios have been carefully studied and the most effective ones are highlighted. Moreover, FOBTV is trying to develop a layered model for the next-generation broadcasting system and taking great efforts toward the ultimate goal of a global harmonized terrestrial broadcasting system. © 1963-12012 IEEE.

Source title: IEEE Transactions on Broadcasting

Series Number: Volume 60 Issue 2

DOI: 10.1109/TBC.2014.2310067

Link: FOBTV: Worldwide efforts in developing next-generation broadcasting system

Zhang, W.; Wu, Y.; Hur, N.; Ikeda, T.; Xia, P.
Blind Self-Calibration Technique for In-phase/Quadrature (I/Q) Imbalances and Direct Current-Offsets

Year: 2014

Abstract: The gain/phase imbalances and DC-offsets in the in-phase and quadrature branches in direct conversion transmitters (DCTs) are main sources of errors, especially at microwave frequencies and above. These impairments distort the spectrum of the transmitted signal and degrade the communications performance. In this paper, a blind technique based on higher order statistics is proposed to estimate the calibration parameters in order to compensate for these impairments. By minimizing a cost function composed of second and fourth moments of the modulator output signal, the DC-offsets, gain imbalance, and phase imbalance can be successively calibrated. The convergence of the proposed technique is also analyzed. This technique is blind in the sense that it does not require any prior knowledge about the DCT input signal, and is applicable to many communications systems including QAM, OFDM, and SC-FDMA. Computer simulations and experiments at 20 GHz demonstrate that the proposed technique can significantly improve the DCT performance in terms of local oscillator leakage and image suppressions.

Source title: Circuits and Systems I: Regular Papers, IEEE Transactions on  (Volume: 61 ,  Issue: 6 )

Series Number: Volume 61 Issue 6

DOI: 10.1109/TCSI.2013.2290826

Link: Blind Self-Calibration Technique for In-phase/Quadrature (I/Q) Imbalances and Direct Current-Offsets

Zhu, Z.; Huang, X.; Caron, M.; Leung, H.
Compensation of delay mismatch in a direct conversion transmitter

Year: 2014

Abstract: This brief analyzes the effects of the delay mismatch (DM) between in-phase (I) and quadrature (Q) branches of a direct conversion transmitter (DCT) on its image rejection capability. An iterative technique is proposed to compensate for the DM, based on the instantaneous power measurement of the DCT output signal. It is shown that the proposed compensation technique can obtain the true DM value even when the I/Q impairment exists in the DCT. Simulation results show that the proposed technique can effectively compensate for the DM, thereby improving the DCT performance. © 2014 IEEE.

Source title: IEEE Transactions on Circuits and Systems II: Express Briefs

Series Number: Volume 61 Issue 12

DOI: 10.1109/TCSII.2014.2356894

Link: Compensation of delay mismatch in a direct conversion transmitter

Zhu, Z.; Huang, X.; Leung, H.
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