Study of Future Demand for Radio Spectrum in Canada 2011-2015

6.3 Backhaul Microwave Facilities

6.3.1 Overview

Although backhaul microwave facilities are used for a wide range of applications, this Study will focus mainly on the demand for backhaul facilities to support the accelerated growth of cellular networks and broadband access systems at frequencies up to 28 GHz. Use of microwave technologies for point-to-point access communications, and its associated demand for spectrum, is covered in the previous section under Fixed Wireless Access.

There has been a major shift in the development of backhaul microwave facilities to support public telecom networks since the mid-1980s. A number of large regional and national fibre-optic-based facilities have been built to accommodate public telephone and data networks, Internet traffic transmission, inter-city carriage of television programming to cable TV head-ends and to DTH broadcasting satellite gateways, as well as to meet other transmission requirements. The role of heavy-route, long-haul microwave radio systems in certain bands below 10 GHz, such as the 4 and 6 GHz bands, has been replaced mostly by large fibre-optic systems. These systems are able to expand their transmission capacity with the adoption of new generation optical multiplexers and repeaters, and advanced signal processing techniques.

There have been similar initiatives undertaken by incumbent telecom carriers, local cable operators and new telecom entrants to build a wide range of fibre-optic systems in urban areas and surrounding communities to complement traditional copper and coaxial distribution facilities for residential and business customers. A main reason for this was to increase the transmission capacity and quality of their broadband Internet and cable TV offerings, including the bundling of multiple services (IPTV, telephone, broadband).

As for microwave facilities, there has been considerable activity in the 1990s in rolling out point-to-point links in the 23 GHz and 38 GHz bands to serve large business customers. At that time, a significant amount of spectrum was licenced using competitive processes for point-to-multipoint broadband access in the 24/28/38 GHz bands, the 2500 band and the 2300/3500 MHz bands. Point-to-multipoint spectrum below 6 GHz has been gradually assigned for FWA broadband access. FWA to households has not been economically viable in the 24 GHz to 38 GHz range due to the historic lack of cost-effective Consumer Premise Equipment (CPEs) for residential use. However, some of the spectrum is being used effectively for short-haul backhaul links.

Therefore, while the incumbent telecom and cable operators have extensive wireline-based facilities (copper/fibre and coaxial/fibre), microwave backhaul and FWA provide them another transmission alternative. For new entrants in cellular and broadband, the use of FWA and microwave backhaul are, often, their only options.

Given the number of national and regional cellular networks with thousands of cell sites concentrated in Southern Canada, and the rapid growth of mobile traffic, the use of backhaul microwave facilities has significantly increased to link clusters of cell sites to collector points and public switching networks. Due to the relatively short distances between cell sites in urban areas, the use of microwave spectrum in the Ku- (11/14 GHz) and Ka- (18/21 GHz) bands has exceedingly been in demand for backhaul. There has also been an increased use of these bands for microwave backhaul to support broadband Internet access using FWA bands below 6 GHz.

The demand for microwave backhaul facilities and spectrum will be studied within the context of other backhaul transmission facilities, mainly fibre-optical systems and copper-based digital operators providing extensive routing of traffic of cellular and broadband Internet distribution services.

6.3.2 Spectrum Inventory and Spectrum Utilization

The Inventory Report (Section 2.0) reviews the number of frequency assignments in the fixed-service frequency bands (both point to point and point to multipoint). It considers various factors, including regional distribution and geographical concentration, metropolitan/non-metropolitan usage, growth of frequency use, and trends over the last 10 years for selected bands.

The spectrum of interest for backhaul facilities in this Study is the frequency bands above 10 GHz for two-way point-to-point microwave links. These links are in increasing demand, as a result of growth in traffic of mobile cellular networks and broadband distribution systems. Specifically, the 11 GHz, 14 GHz, 18 GHz and 23 GHz bands are of interest. These bands are experiencing the greatest demand to provide short transmission links in urban and rural areas.

The Inventory Report summarizes the number of frequency assignments for two-way microwave bands between 2 GHz to 38 GHz. A number of these bands in this spectrum range have been identified as prime bands for backhaul facilities supporting cellular and wireless broadband access networks. Both of these network types are experiencing a very high demand for backhaul facilities. Microwave bands above 10 GHz are well suited for short hops (typically less than 16 km) to link cellular and broadband sites to their respective networks directly or through other transmission facilities. Microwave bands below 10 GHz provide for much longer hops (20–50 km) and are intended for medium-to-long-haul transmission, often as provincial or inter-provincial systems. Figure 6.3.1, below, taken from Chapter 2 of the Inventory Report shows the number of frequency assignments in the various fixed point-to-point microwave bands, and the relative interest for spectrum in the 11 GHz, 14 GHz, 18 GHz and 23 GHz range for microwave backhaul facilities.

Figure 6.3.1 — Total Number of Fixed Land Station Frequencies Assigned

Total Number of Fixed Land Station Frequencies Assigned (the long description is located below the image)

Source: Inventory Report, Figure 2.1, Section 2.3.2

Description of Figure 6.3.1

This graph shows the total number of fixed land station frequencies assigned across the spectrum. The values from the graph are summarized in the following table:

Total Number of Fixed Land Station Frequencies Assigned
Frequency Range Number of Assignments
953-960 MHz 1314
1700-1710 MHz 1477
1780-1850 MHz 477
2025-2110 MHz 2474
2200-2285 MHz 896
3700-4200 MHz 133
5925-6425 MHz 3973
6425-6930 MHz 3420
6930-7125 MHz 2295
7125-7725 MHz 2942
7725-8275 MHz 1051
8275-8500 MHz 473
10550-10595 MHz 991
10615-10660 MHz 991
10700-11700 MHz 3617
12700-13250 MHz 2618
14500-14875 MHz 3597
14875-14975 MHz 212
14795-15350 MHz 3605
17800-18300 MHz 4671
19300-19700 MHz 4672
21800-22400 MHz 3609
23000-23600 MHz 3611

Some of the key insights in the Inventory Report that are relevant to the scope of this Study include:

  • The 11 GHz, 14 GHz, 18 GHz and 23 GHz bands are experiencing an exponentially high growth of frequency assignments. This is likely being driven by increasing capacity requirements in support of cellular and broadband access networks;
  • The highest number of frequency assignments across Canada are found in the 18 GHz band, with the majority of assignments in Ontario at close to 4600;
  • The second-highest number of frequency assignments is in the band 5925-6425 MHz, with nearly 4000 assignments. This is likely due to the re-channellization of part of the band to support low-capacity microwave systems via a larger number of narrowband channels;
  • An average of approximately 65% of all backhaul links are located in non-metropolitan areas; and
  • The number of assignments in metropolitan areas tends to be greater in bands above 14 GHz, with the exception of the 6930-7125 MHz band.
  • The Inventory Report identified new spectrum for backhaul below 10 GHz in the bands 7975-8025 MHz and 3700-4200 MHz; and above 10 GHz, in the bands 12.7-13.2 GHz and 28 GHz.
  • We note that 600 + 600 MHz of fixed microwave spectrum has been reserved since the early 1990s in the paired bands 21.2-21.8/22.4-23.0 GHz. This band is adjacent to the popular paired spectrum in bands 21.8-22.4/23.0-23.6 GHz, where technology readily exists.
  • It can also be observed that, despite the availability of suitable technology, there is unassigned spectrum in the 31 GHz range, which could provide more spectrum for backhaul microwave facilities.

6.3.3 Stakeholder Input and Research Analysis

Stakeholder Input

  • Service providers highlighted the benefits of microwave backhaul facilities, including:
    • Microwave provides a cost-effective way to rapidly deploy facilities, and transport traffic from cell sites to aggregation points. This is especially important for new entrants having limited fibre-optic and wireline facilities.
    • Microwave backhaul supports broadband distribution networks. Some broadband FWA hubs have moved from 36 Mbps to 150 Mbps with further expansion planned in the near future.
    • Currently, HSPA sites use microwave backhaul links with 150 Mbps capacity. These links can support 220 Mbps capacity. When LTE sites are launched, the capacity will grow to support 530 Mbps.
    • With the aggregation of traffic in multi-hop backhaul relays, the capacity of these hops is 2 to 3 times that of an average busy site.
  • Service providers also indicated their perspective on future needs as:
    • The deployment of 4G technology, for broadband services, will have dramatic demand on backhaul capacity in the next five years.
    • An incumbent local exchange carrier (ILEC) expects exponential growth in backhaul capacity needs in the coming years.
    • A wholesale microwave backhaul provider projected 20% annual growth for microwave-backhaul-capacity needs, driven by incremental bandwidth demanded by businesses.
    • Another operator, discussing highly congested areas of Toronto and Ottawa suggested that it expects its backhaul capacity needs to grow by up to 25 times over the next five years.
  • Comments by some indicated that they are moving to fibre optic to save costs:
    • Meanwhile, it was also noted that, over time, multiple microwave channels will be needed per link, which are more expensive than fibre facilities. Therefore, it is expected that there will be an increase in the use of fibre-optic-based systems to backhaul.
    • A public power utility indicated that they have replaced microwave with fibre optic connections already, as a result of the long-term cost benefits for them.
    • Another major ILEC and CLEC carrier indicated that most of their heavy-transmission routes have moved from microwave to fibre. It also indicated that the majority of its light-transmission routes, that have more than two hops, will be replaced by fibre within five years. However, for the foreseeable future, it sees using microwave backhaul for switching office transport and to access remote sites, where fibre costs are prohibitive.
    • In lieu of deploying heavier capacity microwave systems, a facilities service provider reported that it continued to maintain dark and leased fibre facilities to aggregate traffic and to offload over-exerted microwave links. Although this has helped alleviate short-term needs along busy corridors, it does not meet the redundancy requirements for some Canadian businesses.
  • Current use of various bands was addressed by several stakeholders as follows:
    • It was noted that bands used for the types of hops are as follows:
      • Long hops: 6, 7, 8 GHz
      • Medium hops: 11, 15 GHz
      • Short hops: 18, 23 GHz
    • Some observed that, in some cases, the 24 and 28 GHz, even the 38 GHz, FWA bands for point-to-multipoint applications have been treated more like backhaul bands and as broadband pipes to enterprises.
    • As growing rural expansion requires long hops and spectrum below 10 GHz, concern was expressed about the limited available channel bandwidth of 30 MHz.
    • A provincial ILEC is using a mixture of 2, 6 and 8 GHz microwave system in rural and remote northern regions.
    • New entrants are using several bands for backhaul, including 11 GHz, 14 GHz, 18 GHz and 23 GHz bands, plus the 24 GHz and 38 GHz bands in large urban centres. Transmission capacity ranges from 30 Mbps up to 227 Mbps with channel bandwidth of 4 MHz to 10 MHz. In many cases, those without existing wireline facilities see an annual growth of 50% in the use of microwave assignments.
    • A large broadband service provider indicated using the four prime bands above 10 GHz with bandwidth ranging from 30 MHz to 50 MHz, to support up to 300 Mbps capacity, depending on the number of relay hops. The first link from a point of presence (POP), or where the link connects to the fibre backhaul facility, has the highest transmission capacity. In the near future, with 4G broadband, the minimum microwave backhaul capacity is expected to rise to 150 Mbps. Hence, the last microwave link connected to the fibre system for three to four broadband sites will require 500 Mbps capacity.
    • A national cellular operator reported primarily using the 11 and 18 GHz band for microwave backhaul. These links are mainly used in mid-urban areas, and the anticipated capacity requirement in five years is 1 Gbps, with increments expected as follows:
      • 2011: 134 Mbps;
      • 2012: 300 Mbps;
      • 2013: 500 Mbps;
      • 2014: 750 Mbps; and
      • 2015: 1 Gbps.

      Over the last five years, for medium-haul backhaul, the carrier has preferred to use fibre optic than microwave. The capacity for these microwave links has jumped from 15 Mbps up to 135 Mbps per MW hop.

    • According to a facility carrier, its microwave backhaul has reached more than 70% utilization on some hops and will require solutions in the short term to sustain the incrementing traffic load. Markets with high-spectrum utilization, such as the GTA, Montreal, Calgary and Vancouver, are expected to be at 80%-100% capacity within the next five years.
  • As expected, respondents indicated that some bands are becoming congested in certain regions:
    • There is increased congestion surrounding Toronto and Ottawa in the 18 GHz and 23 GHz bands, due to new cellular operators.
    • CLEC indicated challenges in coordinating frequencies at 11 GHz in Toronto to avoid interference from other users. Examples of such areas include the Greater Toronto Area (GTA) and Greater Vancouver Area (GVA), both congested at 11 GHz.
    • The GTA, GVA, Calgary, Edmonton and Montreal also have a high level of utilization in the 18 GHz band.
    • It was suggested that 11 GHz faces very challenging congestion in Ontario, due to the 15-GHz moratorium, which is displacing many links into the 11 GHz band. In addition, LTE will put pressure on 11 GHz in more urban areas. The 6 GHz could see issues in rural areas, as expansion continues and several long hops are required. In fact, it was noted that the upper 6 GHz is already experiencing congestion in Alberta.
  • There were some exceptions for regional carriers who reported sufficient spectrum for their use:
    • A provincial ILEC carrier uses the 2, 6, 7, 11, 18, 24 and 38 GHz bands to establish backhaul facilities for mobile and broadband traffic. The carrier does not experience any congestion, nor does it foresee any congestion in the next five years.
    • Another regional carrier indicated using a large amount of fibre infrastructure. Microwave is used only in remote areas where deployment of fibre is too difficult and costly. In these remote areas, there are a sufficient number of channels available in the 6 and 8 GHz bands to provide capacity for the present and foreseeable future.
  • Recommendations by some respondents included:
    • Spectrum should be allocated in the 13 GHz band, which provides similar propagation characteristics as 11 GHz, and the 80 GHz band, as well, which is instrumental in supplying multiple gigabit access in dense urban areas. Both bands currently have equipment from Canadian and U.S. radio vendors.
    • 50 MHz channels are especially preferred because they maximize the potential of the hardware. Currently, all new microwave hardware deployed is capable of supporting 50 MHz channels but is typically used only with 30 MHz channels. 40% of the radio's potential is going untapped in this scenario.
    • Utilize Cross-polarization whenever possible to maximize capacity on a single channel.
    • Make use of adaptive modulation (up to 256 QAM) in order to provide the highest-possible best-effort data rates.
    • Deploy fibre where feasible, as it has better scalability.
    • Systems in the 11 GHz band utilize high-modulation schemes up to 256 QAM, with good propagation and small channel bandwidths of 30 MHz–40 MHz; the spectral efficiency allows capacity up to 200 Mbps. In addition, the spectral efficiency is doubled by employing two independent microwave links, by using a single assigned pair on both polarities along the same path. This supports aggregated traffic upwards of 400 Mbps. With authorization to use 50 MHz of channel bandwidth, radio systems can achieve the same 400 Mbps at 256 QAM on a single radio and 800 Mbps at 256 QAM, when employing dual radio systems.

Research Analysis

As a review of trends in other markets, the U.S. market was reviewed. As can be noted, there are several parallels in the Canadian market to the U.S.

A 2009 FCC ReportFootnote 22 on Mobile Wireless Competition summarizes the situation with backhaul facilities supporting cellular networks. It notes that, with growing mobile voice and data traffic, the existing backhaul facilities need to accommodate greater transmission capacity and, often, these facilities need major rebuilds. The U.S. study noted that cell-site backhaul capacity had increased four-fold between 2007 and 2011.

Three major technologiesFootnote 23 are being employed for backhaul transmission, mainly digital wireline, fixed microwave and fibre-optical systems. The U.S. study estimated that, in 2009, some 71% of the backhaul traffic was carried over wireline carriers, 16.8% over fibre systems, and 12.3% using microwave transmission. In comparison to 2005, there was a decrease of 15% in the use of wireline systems, and, consequently, an increase of 11% for fibre optic and 4% for microwave systems.

Much like the U.S., it can be seen that, in Canada, several trends in the mobile market have led to the increased demands for backhaul capacity. The rapid growth of mobile computing devices incorporating video and Internet browsing has resulted in much higher bandwidth consumption than previously anticipated. As smartphone penetration accelerates, data services are becoming a dominant percentage of the overall traffic. The U.S. report noted that mobile data traffic is growing at exponential rates, and competitively priced mobile Internet services are enabling subscribers to consume more. The conditions in Canada are expected to replicate the U.S. experience.

The rollout of HSPA and HSPA+, with greater transmission speed, the availability of high-end smartphones and tablets, aircards for netbooks and laptops with an ever-increasing number of applications, will greatly increase the backhaul capacity requirements. Further, pressure will be exerted on backhaul facilities in the next year or so with the rollout of 4G mobile networks with a much higher access speed.

In Canada, Telcos have built significant fibre- and wireline-based distribution facilities in populated areas, along major highways and to many rural communities. Similarly, Cablecos have built significant fibre-distribution facilities in populated areas and between various cities. These facilities accommodate the needs of their cellular and broadband services. New-entrant operators have the challenge of rolling out their own facilities in a timely manner. Therefore, in many cases, new entrants must negotiate the use of backhaul facilities from existing carriers.

A significant number of fibre-optic facilities support many of the provincial broadband initiatives. In cities, the traffic of a cluster of three to five cell sites is often routed to a central control site by single aggregated microwave links and then routed off to fibre backhaul rings and wireline digital carriers. Cellular traffic can be typically offloaded at any of many points in a cellular network. In suburban and rural areas, microwave backhaul facilities often route mobile traffic over a few radio hops, and there is an accumulation of traffic as cell sites are added.

The Inventory Report summarizes the number of frequency assignments for two-way microwave bands between 2 GHz to 38 GHz. A number of these bands have been identified as the prime spectrum for backhaul facilities for the expanding number of cellular networks and for wireless broadband access systems. The microwave bands above 10 GHz are well suited for short hops (typically less than 16 km) to link cellular sites and broadband access hubs directly to networks or through other transmission backhaul facilities. Microwave bands below 10 GHz provide for much longer hops (20-50 km) and are most suitable for medium-to-long haul inter-city microwave transmission systems.

The Study concentrates on the microwave backhaul facilities used to carry the traffic of fixed and cellular networks. Several different backhaul technologies are deployed to meet the ever-expanding traffic demand of cellular and broadband Internet networks. The main wireline facilities are digital-wireline carriers and fibre-system carriers.

As another wireless alternative to microwave backhaul, fixed bent-pipe satellites often provide backhaul to northern and remote communities.

This section of the Study focuses on the microwave backhaul in the 10 to 23 GHz bands. These facilities are greatly used in urban and surrounding areas. They have also been extensively deployed as short-distance links for handling cellular sites and rural fixed broadband traffic.

Result of Analysis

The distribution of cellular towers across CanadaFootnote 24 has been reviewed to get a sense of the concentration of cell sites and associated backhaul microwave facilities. While not precise, however, a relatively decent estimate can be made of the backhaul requirements, assuming a mix of transmission facilities, including microwave backhaul links. This, in addition to information from the Inventory Report and other sources, was used to derive the estimates shown in the table below. The table shows an estimate of frequency assignment density per 100 square kilometres in Ontario cities.

Table 6.3.1 — An estimate of the highest frequency-assignment density areas of Canada,
assuming that city area is approximately 10% cellular coverage area
Total Frequency Assignments [FA] in Canada Percentage of FAs Assigned to Canadian Cities Portion of Canadian City FAs Assigned to Ontario Cities Est. of FAs for Ontario Cities Est. area of Ont. Cities (10% of cell coverage of 150,000 sq. km.) [sq. km.] FA density per 100 sq km. for Ontario Cities [FA/sq. km.]
11 GHz

500 + 500
(Now 375 + 375) MHz
3700 FA 23%

(851 FA)
45 %

(i.e. 383 FAs out of 851 FAs)
383 FA 15,000 2.5
14 GHz

375 + 375 (Now 215 + 215) MHz
7400 FA 33%

(2442 FA)
47 % 1150 FA 15,000 7.7
18 GHz

500 + 500
9600 FA 53%

(5088 FA)
45% 2290 FA 15,000 15.3
23 GHz

600 + 600
7200 FA 75 %

(5400 FA)
40 % 2160 FA 15,000 14.4

Source: Red Mobile Analysis based on Ontario cities, derived from Inventory Report Figures 2.2 and 2.3, and other sources, as discussed

It can be noted that the Ontario Region has between 40% and 50% of all frequency assignments in Canada in the four prime bands. An assessment of the spectrum density of the Ontario cities is a good proxy of the highest frequency assignment areas of Canada.

Some additional observations based on interviews, review of research and industry participants include:

  • The 11 GHz, 14 GHz, 18 GHz and 23 GHz bands are of main interest for cellular and broadband backhaul. Significant spectrum was reassigned in the 11 GHz and 14 GHz to accommodate DTH satellite and military services, of late.
  • The 11 GHz and 18 GHz bands are the most popular microwave bands used by wireless carriers. In certain regions, an estimate of 20% and 35% spectrum vacancy may exist in the respective 11 GHz and 18 GHz bands, based on efficient spectrum planning. As opposed to this, in other areas, such as in London and Ottawa, there are only limited frequency assignments available in the 11 GHz band.
  • There is a need for microwave links having greater than 30 MHz bandwidth (50 MHz or more) and larger capacity due to the ever-increasing mobile data growth;
  • There is interest in the 4 GHz band for microwave backhaul. This band is currently under-utilized.

6.3.4 Services and Spectrum Demand

As with the other services, the projections for service demand in terms of traffic were first set out, then, based upon further review and analysis, relevant assumptions were used to convert these projections for traffic into a demand for spectrum. These were, then, modelled to develop projections for spectrum demand.

Service Demand: Market Analysis

It is estimated that there are approximately 28,000 bidirectional microwave backhaul links, with a further breakdown estimated as just more than 75% (21,500) for fixed networks and 6,500 for cellular. The fixed network backhaul links tend to be in deep rural/low-density locations;cellular backhaul links are a mix of urban and rural.

As busy links reach capacity and require upgrading, and as the economics of fibre versus microwave changes, there is a continuing offload of links and traffic from microwave to fibre-based systems.

The traffic that these links carry is estimated to increase in volume, but decline as a proportion of the total traffic carried by the fixed and cellular telecoms' networks, as follows:

  • For fixed networks, the proportion of fixed network traffic carried over microwave backhaul declines from 10% to 5% over the period of 2010-15.
  • For cellular, the proportion of cellular network traffic carried over microwave backhaul declines from 50% to 25% over the same period.

In both cases, this means that the volume of traffic carried over microwave backhaul continues to increase, but it increases at a slower rate than the trajectory for the total traffic over the network.

Figure 6.3.2, below, shows the projected growth in traffic over microwave backhaul. Fixed network traffic dominates, but cellular is projected to contribute to a growing proportion of the total traffic.

Figure 6.3.2 — Growth in traffic, Microwave backhaul

Growth in traffic, Microwave backhaul (the long description is located below the image)

Source: Red Mobile Projections

Description of Figure 6.3.2

This chart provides the growth in traffic for microwave backhaul in GB/mo for both fixed networks and cellular networks. The growth in traffic, from 2007-2015 is summarized in the following table:

Growth in traffic, Microwave backhaul
Fixed Backhaul Cellular Backhaul
2007 12,480,000 961,248
2008 17,280,000 1,149,540
2009 21,120,000 1,397,125
2010 28,800,000 1,973,214
2011 38,880,000 3,879,868
2012 48,000,000 7,347,672
2013 58,800,000 12,693,111
2014 72,000,000 17,473,288
2015 84,000,000 21,010,500

Key Assumptions and Relationship between Service and Spectrum Demand

Assumptions are given separately for Fixed and Cellular backhaul networks.

The main assumptions regarding fixed networks backhaul are as follows:

  • Fixed network data traffic for residential subscribers is 15 GB/subscriber/month in 2010, rising to 90 GB in 2015.
  • This traffic is scaled up by a factor of 1.6 to allow for non-residential traffic and non-data (voice) traffic.
  • The number of links declines at 5% per annum;
  • By 2015, 10% of the fixed network microwave backhaul traffic is routed over links operating at frequencies at or above 38 GHz. The traffic carried over these links is included in the projected traffic volumes for the microwave backhaul service, but removed before the demand for spectrum is calculated.
  • Busy-hour traffic is 3.5 times that in the average hour, and required headroom (for minimizing latency, etc. and for delivering burst rates to individual users) is six times the average-hour traffic (approximately 1.7 times the busy-hour traffic).
  • A factor of two is applied to allow for dual routing/ring architectures.
  • A further factor of two is applied to the required capacity, to allow for some future growth in traffic without needing a further install of equipment.
  • Spectral efficiency is 4 bits/sec/Hz, rising by 5% per annum.
  • Backhaul links are often required to operate in series. A busy link needs to be dimensioned to carry traffic for six times the traffic on an average link.
  • Where there are multiple operators in the same neighbourhood, backhaul links are licensed and implemented in a coordinated fashion across operators. A frequency reuse factor of three is sufficient to avoid interference between neighbouring/co-aligned links.
  • Backhaul spectrum is all paired.
  • So in total it is assumed that when a busy link (i.e. the link for the RAN site nearest to the core network) is dimensioned, it is sized to cope with the average traffic from thatRAN site, scaled up as follows:
    • 6 times for busy hour and required headroom for thatRAN site
    • Another 6 times for busy link, i.e. its carrying traffic for 5 otherRAN sites as well
    • 3 times for ring architecture / resilience, i.e. it needs to be able to cope with a break elsewhere on the backhaul ring
    • 2 times for future - proofing

    Therefore, the Grand total is about 200 times the average hour traffic of theRAN site.

The main assumptions regarding Cellular networks backhaul are as follows:

  • Cellular network voice and data traffic, for residential subscribers, is as described in the section on Cellular Services above.
  • The number of links increases at 10% per annum.
  • By 2015, 15% of the cellular network microwave backhaul traffic is routed over links operating at frequencies at or above 38 GHz. As with fixed backhaul, this traffic is included in the projected traffic volumes, but removed before the demand for spectrum is calculated.
  • Where there are multiple operators in the same neighborhood, cellular backhaul links are licensed and implemented in a coordinated fashion across operators. A frequency reuse factor of six is sufficient to avoid interference between neighbouring/co-aligned links.
  • The other assumptions — Busy hour, Required Capacity, Capacity for future growth, Spectral Efficiency, dimensioning for busy links and pairing — are all the same as for fixed networks backhaul.

Demand for Spectrum

Figure 6.3.3 shows the growth in the demand for spectrum. This demand is projected to grow by a factor of about three, slightly slower than the growth in traffic.

The drivers of this difference are: improvements in spectral efficiency and substitution to frequencies above 38 GHz.

There is also a shift in spectrum required, from fixed backhaul to cellular backhaul. This is driven by faster growth in cellular network traffic, but is offset slightly by an increase in the number of cellular backhaul links.

Figure 6.3.3 — Demand for Spectrum, Microwave backhaul

Demand for Spectrum, Microwave backhaul (the long description is located below the image)

Source: based on Red Mobile and PA analysis, and PA PRISM Modelling

Description of Figure 6.3.3

This chart provides the demand for spectrum for microwave backhaul in MHz for both fixed networks and cellular networks. The demand for spectrum, from 2007-2015 is summarized in the following table:

Demand for Spectrum, Microwave backhaul
Fixed Backhaul Cellular Backhaul
2007 307 MHz 79 MHz
2008 426 MHz 90 MHz
2009 522 MHz 103 MHz
2010 713 MHz 164 MHz
2011 965 MHz 276 MHz
2012 1,195 MHz 463 MHz
2013 1,438 MHz 667 MHz
2014 1,693 MHz 726 MHz
2015 1,896 MHz 708 MHz

As with some of the other services, there are further factors not included in the projections (above) that are likely to create a balancing feedback loop. So, if spectrum did start to become a constraint for operators, they may have viable options for mitigating this, albeit at some cost. These options may include offloading a larger percentage of the traffic onto fibre, where possible, for high-demand areas/links; and/or greater substitution to higher frequency bands above 38 GHz, where feasible.

Assessment of Alternative Scenarios

Projections for trafficand for spectrum demand for microwave backhaul are shown in Figure 6.3.4 and Figure 6.3.5.

The primary differences between the scenarios are as follows:

Scenario 2:

  • Higher traffic growth, by 2015, there is 1.5x the fixed network traffic and twice the cellular network traffic of Scenario 1.
  • Share of traffic routed over microwave backhaul declines faster; by 2015, it is down to 4% of fixed network backhaul, rather than 5%.
  • Take-up of frequencies above 38 GHz is twice as fast as in Scenario 1.
  • Spectral efficiency improves at 7% pa, instead of 5%.

Scenario 3:

As with the other services, the underlying traffic growth on the fixed and cellular networks in Scenario 3 is the same as it is in Scenario 1. However, as there is less investment in fixed facilities for Scenario 3, therefore, more traffic goes over microwave backhaul in this case. Thus, we note a divergence in Scenario 3 mainly on the following inputs:

  • Scenario 3 has less investment in fixed-network fibre backhaul, resulting in the share of traffic routed over microwave backhaul declining 30% more slowly over the period 2010-15 — reaching 7% of fixed network backhaul, rather than 5%. This results in some 50% higher volumes of traffic over microwave backhaul in Scenario 3, when compared against Scenario 1.
  • This reduced investment in fibre backhaul also results in a 5% per annum (pa) growth in the number of fixed network microwave backhaul links.
  • There is little or no migration to frequencies above 38 GHz.
  • Spectral efficiency improves at 3% pa instead of 5%.

The net result of these differences is that Scenario 3 (Low Investment) has the highest level of microwave backhaul traffic in 2015.

Figure 6.3.4 — Microwave Backhaul Traffic, by Scenario

Microwave Backhaul Traffic, by Scenario (the long description is located below the image)

Source: Red Mobile Projections

Description of Figure 6.3.4

This chart provides the total growth in traffic for microwave backhaul in GB/mo for each of the three scenarios. The growth in traffic, from 2010-2015 is summarized in the following table:

Microwave Backhaul Traffic, by Scenario
Backhaul BAU Low Inv.
2010 30,773,214 30,773,214 30,773,214
2011 42,759,698 43,276,668 43,790,792
2012 55,347,672 58,921,871 62,350,539
2013 71,493,111 80,410,314 88,592,659
2014 89,473,288 106,367,119 121,960,620
2015 105,010,500 131,880,390 157,453,253

When converted into a demand for spectrum, the higher traffic growth in Scenarios 2 and 3 is offset by differences in spectral efficiency, rates of growth/retention of microwave links, and offloads to frequencies above 38 GHz.

The resulting projections from spectrum demand are shown in the chart below. The net effect is that Scenarios 1 and 2 have similar demands for spectrum, and Scenario 3 has a slightly higher demand.

Figure 6.3.5 Microwave Backhaul – Spectrum Demand by Scenario

Microwave Backhaul – Spectrum Demand by Scenario (the long description is located below the image)

Source: Red Mobile Projections

Description of Figure 6.3.5

This chart provides the total demand for microwave backhaul in MHz for each of the three scenarios. The spectrum demand from 2010-2015 is summarized in the following table:

Microwave Backhaul – Spectrum Demand by Scenario
Backhaul BAU Low Inv.
2010 878 MHz 878 MHz 3394 MHz
2011 1241 MHz 1258 MHz 1271 MHz
2012 1658 MHz 1721 MHz 1750 MHz
2013 2104 MHz 2176 MHz 2356 MHz
2014 2419 MHz 2475 MHz 2935 MHz
2015 2603 MHz 2621 MHz 3394 MHz

6.3.5 Conclusion

The Study has modelled the relative traffic (GB/mo) levels of the microwave backhaul facilities in the prime microwave bands (i.e. 11/14/18/23 GHz) bands, to carry cellular network and FWA broadband traffic (to collector points or concentrators) for the period 2010-2015. Then, the Study has converted these traffic levels of cellular and fixed networks to spectrum demand for the same period.

Results suggest that the prime microwave backhaul bands (i.e. 11/14/18/23 GHz) bands will see an increase in their demand for spectrum over the period of 2010-15, as HSPA and LTE networks drive growth in cellular traffic, and as fixed networks increase their appetite for high-capacity microwave backhaul links.

Date modified: