E-band Wireless Comms: UK Announces New Approach

On Dec. 16 2013, Ofcom—the UK telecom regulator—announced a new approach for the use of E-band wireless communications in the United Kingdom. This new approach results from an earlier Ofcom consultation exercise in which Aviat Networks participated.

To summarize, the new approach, which is available for licensing after Dec. 17, 2013, splits the band into two segments. Ofcom will coordinate the lower segment of 2GHz, while the upper segment of 2.5GHz will remain self-coordinated as per the prior policy.

The segment Ofcom coordinates will follow the usual regulatory processes for all the other fixed link bands it oversees. Moreover, Ofcom has already updated all the relevant documents and forms to accommodate E-band. While we (i.e., Aviat Networks, other telecom vendors) would have preferred the larger portion of spectrum to have been granted to the Ofcom-coordinated process, we welcome this new arrangement because it provides an option for greater security and peace of mind to operators in terms of protection from interference than was envisaged for the previous all self-coordinated spectrum regime.

For a more detailed look at the new E-band arrangement, Figure 1 shows the Ofcom-coordinated section sitting in the lower half of both the 71-76GHz and 81-86GHz bands thus allowing for the deployment of FDD systems in line with ECC/REC(05)07.

figure-1-segmented-plan-for-mixed-management-approach-aviat-networks-blog-on-ofcom-e-band-policies-18dec13.jpg

Figure 1: Segmented Plan for Mixed Management Approach (click on figures to enlarge)

In terms of channelization within the Ofcom-coordinated block, the regulator announced that it would permit 8 x 250MHz channels, 4 x 500MHz channels, 1 x 750MHz channel and 1 x 1000MHz channel as per ECC/REC(05)07. Ofcom also stated that 62.5MHz and 125MHz channels will be implemented as soon as the relevant technical standards, etc., from ETSI are published. Figure 2 shows the Ofcom channel plan:

Figure-2-Ofcom-Permitted-E-band-Channelizations-Aviat-Networks-blog-on-Ofcom-E-band-policies-18Dec13

Figure 2: Ofcom Permitted E-band Channelizations

Regarding equipment requirements, Ofcom stated that it will allow equipment that meets the appropriate sections of EN 302 217-2-2 and EN 302 217-4-2. This includes the antenna classes (e.g., classes 2-4) that will allow the deployment of solutions with flat panel antennas. Aviat Networks welcomes this approach and hopes that other regulators—notably the FCC in terms of antenna requirements—currently considering opening up and/or revising their rules for E-band adopt similar approaches.

The license fees for the self-coordinated segment remains at £50 per link per annum, whereas in the Ofcom-coordinated segment the fees are bandwidth based as reflected in Figure 3:

Figure 3-Ofcom-Bandwidth-based-Fees-Aviat-Networks-blog-on-Ofcom-E-band-policies-18Dec13

Figure 3: Ofcom Bandwidth-based Fees

Notwithstanding the current fees consultation process that Ofcom is undertaking, these “interim fees” will remain in place for five years, after which time the results of the fees review may mean that they will be amended.

Also because of responses received during the consultation process, within the self-coordinated block, Ofcom will now require the following additional information for the self-coordination database: antenna polarization (horizontal, vertical or dual), ETSI Spectrum Efficiency Class and whether the link is TDD or FDD.

Ian Marshall
Regulatory Manager
Aviat Networks

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Feds Update Spectrum Release to Relieve Wireless Congestion

Photo of HTC Mogul smartphone

Smartphones such as the HTC Mogul are driving the demand for more wireless spectrum to be released.

To help relieve wireless network congestion, the Obama Administration made a commitment to release up to 500 MHz of spectrum for reuse in commercial wireless solutions. In April 2011, the NTIA updated the progress toward this commitment in its first interim report. This 500 MHz of spectrumcomprising 280 MHz of underused commercial spectrum and 220 MHz of federally owned radio spectrum now administered by the NTIAwould help ease the growing shortage of spectrum as demands on the wireless network rise. This demand is primarily fueled by the explosive adoption rate of smartphones and other mobile broadband devices and the corresponding infrastructure—both access and mobile backhaul—required to support their use.

The timescales and conditions for the availability of this spectrum is in the hands of the FCC and is expected to take about five years as the first part of its 10 year plan. However, the first four blocks of spectrum have recently been identified for release by the NTIA at 1675-1710 MHz, 1755-1780 MHz, 3500-3650 MHz, 4200-4220 MHz and 4380-4400 MHz.

It is estimated that an auction of 500 MHz of spectrum could raise more than $20 billion for the U.S Treasury.

Many wireless technology industry commentators expect the lower bands to be taken up for wireless access. But the higher three bands could be allocated for mobile backhaul use to begin the process of easing congestion in the current 6GHz bands.

The microwave backhaul industry welcomes this first step. We look forward to follow through on further spectrum releasesespecially in the 4 to 8GHz range—which is suitable for high-capacity trunking backhaul.

Ian Marshall
Regulatory Manager, Aviat Networks

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Small Cell Mobile Backhaul: The LTE Capacity Shortfall

With immense mass-market demand for mobile broadband services, and emergence of new high-capacity mobile devices (e.g., smartphones, tablets) and applications, many of the world’s most advanced mobile networks are struggling to deliver a high-quality consumer experience. Explosion of per-user data consumption, combined with subscriber growth and mobility needs, is putting today’s networks are under tremendous pressure. In addition, as operators continuously evolve networks with the latest technology (e.g., 2G, 3G, 4G) to meet these capacity and coverage demands, network costs are exploding and operators are struggling to keep up profitable businesses.

LTE, representing a 4x capacity improvement over current 3G networks, on its own will be insufficient to address all future capacity demands, as mobile data traffic will double every year equating to a 32x growth by 2014 (Figure 1).

32x backhaul capacity demand jump

Figure 1: The forecast 32x jump in data demand cannot be met alone by LTE, which can only offer a 4x increase over current wireless technologies.

Increasing spectral efficiency with new versions of LTE will help manage the shortfall, but these solutions are not yet available and again will not provide the volume of capacity necessary. Acquiring more spectrum would help but additional spectrum is costly and in most cases not available. Traffic management approaches such as caching and mobile data offloading are emerging to help manage the load but because of limited cache hit rates, these solutions will be insufficient to address the capacity shortfall. Offload techniques, such as in-home femto cells and mobile offload gateways, are emerging to reduce load on mobile infrastructure, but again they will be insufficient. A new approach is required.

Emergence of Small Cells

To meet these capacity challenges, and address ever-prevalent coverage issues, new small cell network architectures are emerging based on a new generation of low power, small cell (i.e., micro, pico, femto) mobile base stations. ABI Research estimates 4 million pico base stations will be shipped per year by 2015. Being deployed into an existing network on lampposts, utility poles and building walls, these base stations offer a way for operators to meet challenges of urban, suburban and in-building locations. Combined with existing base station infrastructure, these small cells are transforming the flat macro mobile network into a multi-level, hierarchical radio access network (Figure 2).

Macro, Pico & Femto base stations

Figure 2: Combined with existing macro base station infrastructure, small cells are transforming the flat mobile network into a multi-level, hierarchical radio access network.

Small Cell Backhaul: Wired or Wireless

When considering IP mobile backhaul options, operators must first ponder the choice between wireline or wireless solutions. There is generally no “one-size-fits-all” solution, and in reality we’re likely to see a mix of mobile backhaul technologies deployed to meet the small cell backhaul challenge. However, because of challenging utility pole and lamppost deployments, operators cannot count on fixed line options (e.g., fiber, cable, copper/DSL) being ubiquitously available. Moreover, more than 40 percent of the world’s macrocell base stations are backhauled wirelessly and because of these challenging locations, we’re likely to see a much higher percentage of wireless-based backhaul in small cell applications.

Wireless Backhaul for Small Cells: Challenges

Small cell deployments present a number of challenges—not the least of which is impact on mobile backhaul. Operators—and equipment vendors—must consider the key factors below when selecting (and designing) wireless backhaul solutions for small cells:

Lower cost solutions needed—Smaller cells mean more cells and thus more mobile backhaul. To meet overall cost objectives, lower cost backhaul solutions will be required to make sure small cells can be deployed cost effectively. Typical macrocell backhaul CapEx is about 50 percent of the total base station CapEx, and similar ratios will be required to ensure a cost-effective solution.

Space-optimized solutions required—To improve street-level coverage and capacity, small cells are being deployed on lampposts and utility poles. These challenging deployment locations place demands on the physical attributes of backhaul solutions. Unlike traditional cellsites, typical dish antennas will not be feasible for such deployments. In addition, because of space constraints and operations costs, backhaul and base station hardware integrated into common enclosures would be ideal.

Line-of-Sight (LOS) not possible—Street level, metro area deployments mean line of sight to backhaul hub locations are not always—in fact—rarely possible. Requiring large antennas, combined with lack of LOS characteristics, makes traditional point-to-point wireless backhaul ineffective for most small cell backhaul applications.

Interference must be carefully managed—When it comes to wireless backhaul solutions, close proximity of cellsites creates possible interference issues for the backhaul system. These interference issues are relatively new for backhaul systems and need to be considered.

High-capacity solutions required—Driven by increasing demand for mobile data, backhaul requirements for small cells are expected to approach macro cell capacity requirements (50-100Mbps per cellsite) in the next three years.

Which challenges matter most will depend heavily on how small cells eventually are deployed. Stay tuned for a followup blog post where I discuss small cell backhaul deployment options and available solutions to address these needs. In the meantime, feel free to leave me your thoughts, or comments.

Gary Croke
Sr. Product Marketing Manager, Aviat Networks

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