AT&T, T-Mobile Agree on the Future of Small Cell

AT&T and T-Mobile recently filed comments with the FCC that will enable small cell backhaul in urban cores for greater subscriber connectivity.

AT&T and T-Mobile recently filed comments with the FCC that will enable small cell backhaul in urban cores for greater subscriber connectivity.

In the last few weeks, the future prospects of small cell antennas got brighter and shrank at the same time. AT&T and T-Mobile both filed comments with the Federal Communications Commission (FCC) in support of an industry-wide waiver of rules against flat-panel antennas for backhaul radios in the 70-80GHz bands. Currently, out-of-date FCC regulations about antenna radiation patterns hold back development and deployment of this type of equipment that urban dwellers will find acceptable in big city cores.

The current rules effectively call for the use of parabolic antennas that will be unsightly and would violate the aesthetics considerations and zoning regulations in many city core locations—precisely the type of environment that 70-80GHz radios exist to service. While the FCC regulations seem to necessitate parabolic antennas to keep radio beams focused and from interfering with equipment in the vicinity that uses the same wavelengths, mobile subscribers prefer more visually friendly solutions.

How to get from here to there
For the last few years, Aviat Networks has been working with the Fixed Wireless Communications Coalition and others to get the FCC to update its regulations in the 70-80GHz bands. The problem: when the FCC promulgated these rules, the idea had never occurred to anyone that these bands would ever service small cell applications. And the applications that the FCC’s 70-80GHz rules were designed to support never materialized, with only 5,500 links registered in this spectrum since 2005, according to T-Mobile.

However, with this breakthrough in support from Tier 1 operators like AT&T and T-Mobile, the FCC should feel reassured that granting the waiver to the antenna rules for 70-80GHz bands is in the best interest of all the wireless industry service providers. And with OEMs in addition to Aviat asking for the waiver, no specific vendor will be favored. We urge other wireless service providers, communications equipment OEMs, subscribers and anyone else interested in moving forward as fast as the technology can go to also contact the FCC about granting this industry-wide waiver.

In the meantime, to learn more about urbanized small cell backhaul in the 70-80GHz bands, download this white paper.

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FCC Rule Changes Lower the Cost of Microwave Deployments

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Last Friday, 03 August 2012 saw the release of FCC Report and Order 12-87, which contained some significant changes that will lower the total cost of ownership for many microwave links. The two most significant changes concern antenna sizes and wider bandwidths.

Following lobbying by Comsearch and the Fixed Wireless Communications Coalition (FWCC), within which Aviat Networks plays an important role, the FCC has allowed an additional alternative set of antenna parameters to be used in the 6, 18 and 23GHz bands. These new parameters are an alternative to the existing antenna parameters, which have been retained. It is worth noting that while the FCC does not specify actual antenna sizes, the realization of antennas based upon these new parameters does represent a reduction in size and thus provides for the reduced cost of both CAPEX and OPEX that has already been championed by Aviat Networks and other interested parties. The new working alternative antenna parameters are as follows:

  • 3 feet for the 6GHz band
  • 1 foot for the 18GHz band
  • 8 inches for the 23GHz band

To put these changes into perspective the typical cost of renting space for an antenna on a tower is US$400 + US$100 per foot (diameter) per month. So a link consisting of two 6ft antennas will cost 2x (400 + 6×100) = $2000 per month, i.e. $24,000 per annum.

If the antenna diameter could be reduced to 3 feet the cost is reduced to 2x (400 + 3×100) = $1400 per month, i.e. $16800 per annum—a saving of $7200 per year on a single link!

The above calculations are not only ours but also those of MetroPCS, which is quoted in the report and order. MetroPCS specifically notes, as an example, that “the cost of a microwave dish antenna is approximately $100 per foot per month. Thus, even if the revised rule allows for a reduction of just one foot, the annual savings would be $1,200, and the savings over a ten year period would be $12,000.”

Smaller antennas also open up more options in terms of locations for these antennas, and their smaller size reduces wind loading and the need for specialist mountings and strong towers.

Additionally, the FCC in a further notice of proposed rule making attached to this report and order seeks feedback on allowing similar alternative antenna parameters in the 11 and 13GHz bands. Aviat Networks intends to support this proposal via the FWCC.

Other Changes

With the ever-growing demand for bandwidth the FCC has decided to allow aggregation of two 30MHz channels in the 6GHz band and two 40MHz channels in the 11GHz band, giving maximum bandwidths of 60MHz and 80MHz, effectively allowing a doubling of the capacity of a microwave link. This represents another significant cost saving because this increased capacity can be achieved with the same amount of hardware.

Also in this report and order were changes to the definition of efficiency standards to a bits/sec/Hz standard as proposed by the FWCC, and a clarification of the definition of payload capacity: “The bit rate available for transmission of data over a radiocommunication system, excluding overhead data generated by the system.” The FCC has also introduced a welcome simplification of the rules with regard to bit rate efficiency. FCC Part 101.141 has been amended to include a table (below) that details the efficiency criteria according to two frequency ranges and three bandwidth ranges:FCC new bits/sec/Hz efficiency standard

Aviat Networks welcomes the FCC’s progressive changes as the amendments will stimulate the microwave industry and enhance the cost effectiveness of microwave networks across the United States. We expect the rule changes to be effective approximately in October.

Ian Marshall
Regulatory Manager
Aviat Networks

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42GHz: A New Global Standard for Wireless Backhaul?

Parabolic antennas

With ever-increasing demand for spectrum in fixed services, FWCC has endorsed opening up the 42GHz band as a new global standard for microwave backhaul. (Photo credit: Miguel Ferrando via Wikipedia)

An ever-increasing demand for spectrum has recently turned focus on the 42GHz band. Initially opened in some European countries following the development of ECC REC(01)04, the recently published ECC Report 173 states 12 countries have opened this band including Germany, Norway, Poland, Switzerland and the United Kingdom. In the U.K., this band was part of a wider auction of fixed service bands in 2010, with three operators being granted blocks of spectrum in the 42GHz band as a result.

Building on this growth there is a move to make this band global and earlier this year saw the publication of ITU-R Rec F.2005, which in effect promoted the aforementioned CEPT recommendation to global status. Aviat Networks has been lobbying key regulators to open this band. We are eagerly awaiting a consultation from Canada and responses have already been submitted to recent consultations from France and Ireland containing considerations regarding opening this band. The process is also underway in Finland and Sweden to open up this band. Recently our attention has turned to the United States and whether the FCC will open this band for use by the fixed service.

Back in autumn 2011, Aviat Networks raised this topic within the FWCC (Fixed Wireless Communications Coalition) as the first stage of a petition of rulemaking to the FCC. At first there was only a lukewarm reception to our idea as there was concern that the FCC would refuse the request out-of-hand as some previously released spectrum below 40 GHz is underutilized and, therefore, why is more needed? We pointed out that much of this spectrum (e.g., 39 GHz) was block-allocated by auction and thus has not been readily available to all users and that the licensees have underutilized the spectrum. There is a growing need for spectrum that can be licensed on a flexible, site-by-site basis, and this is reflected by the fact that there are no underutilization issues in bands such as 18 and 23 GHz, which are licensed in this manner. It is no coincidence that auctioned bands tend to underperform in terms of efficiency and utilization. So, undeterred, we forged ahead and this resulted in the production of a FWCC petition to the FCC in May 2012. The FCC has recently placed this petition on public notice, per its procedures. This is a great success for Aviat Networks and our commitment to seeking more spectrum for the fixed service, but the story has not ended here as can be seen from a recent blog entry from the FWCC.

Aviat Networks will continue work with the FWCC to ensure that the FCC gives this proposal full consideration and, having learned important lessons from past spectrum allocations, we will lobby for a flexible approach to the licensing model.

Ian Marshall
Regulatory Manager
Aviat Networks

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FCC: New Spectrum for Wireless Backhaul, Relaxed ACM Rules

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On 9 August 2011, the FCC announced several changes to the rules (Part 101) that govern the use of microwave communications in the Fixed Service bands in the U.S. These changes are great news for operators and will be encouraging increased adoption of microwave technology as a wireless transmission alternative to fiber for next generation mobile networks and fixed/private networks.

New Frequency Band for Fixed Services

The FCC opened 650 MHz of new spectrum for Fixed Service (FS) operators in the 6875-7125 MHz and 12700-13100 MHz bands, which will be shared with the incumbent Fixed and Mobile Broadcast Auxiliary Service (BAS) and Cable TV Relay Service (CARS). These bands will primarily be used as an alternative to the 6 and 11 GHz “Common Carrier” bands in rural areas, where the band is not currently licensed to TV mobile pickup stations used in newsgathering operations.

Frequency allocations in these new bands should commence later this year and will be based upon the existing 25MHz channelization. To facilitate adoption, the FCC is also allowing the use of 5, 8.33 and 12.5 MHz channels, as well as 50 MHz channel operation in the 12700-13100 MHz band using two adjacent 25MHz channels.

Allowing Adaptive Modulation

Adaptive Modulation, or AM—or ACM when used with Adaptive Coding—is a relatively recent innovation in microwave technology that allows the radio to dynamically adapt to path conditions to allow a much higher degree of spectrum efficiency, increased wireless link throughput, use of smaller antennas or a combination of all three benefits.

Up until now, the use of AM was restricted by the requirement to comply with FCC spectrum efficiency rules, which dictate a minimum data rate for certain bands. For example in the 6 GHz band a minimum capacity of 130 Mbit/s, or 3xDS3, must be maintained at all times within a 30 MHz channel assignment, using 64QAM modulation. The FCC now allows AM operation where the capacity of the link may drop below the minimum data rate, as long as the operators “design their paths to be available at modulations compliant with the minimum payload capacity at least 99.95 percent of the time,” or in other words, operators will have to “design their paths to operate in full compliance with the capacity and loading requirements for all but 4.38 hours out of the year.”

Aviat Networks, through our membership of the Fixed Wireless Communications Coalition (FWCC), supported rule changes to permit ACM, and the FCC included in its Rulemaking (Clause 48) our analysis on the benefits of ACM in terms of reducing the costs associated with tower leasing:

By way of hypothetical, consider a single link in the 6 GHz band that would require 10-foot antennas with a 99.999 percent standard instead of 6-foot antennas under the 99.95 percent standard. The total cost increase over a 10-year period in this hypothetical example could exceed $100,000.

The smaller antennas offer a number of advantages over larger ones, including more TCO savings over those 10 years.

Still Under Consideration by the FCC

Of all the new proposals being considered, the FCC also announced a Further Notice of Proposed Rulemaking (FNPRM) to further investigate the following proposals:

  • Allowing Smaller Antennas in Certain Part 101 Antenna Standards without materially increasing interference
  • Exempting Licensees in Non-Congested Areas from Efficiency Standards to allow operators to increase link length in rural areas
  • Allowing Wider Channels, including 60 MHz in the 6 GHz band, and 80 MHz in the 11 GHz bands
  • Revising Waiver Standard for Microwave Stations Near the Geostationary Arc to align with ITU regulations
  • Updating Definition of Payload Capacity rules in Part 101 rules to account for Internet Protocol radio systems

Aviat Networks continues to work on these issues, via the FWCC, which we believe will assist operators in lowering their total wireless network operational costs by taking advantage of the newest innovations that are now available in microwave technology.

With these new rules, along with the potential for further changes under consideration, microwave solutions provide an even more compelling case to enable mobile operators in the U.S. to keep pace with the IP mobile backhaul capacity demand driven by the introduction of new 4G wireless/LTE wireless networks.

Ian Marshall
Regulatory Manager, Aviat Networks

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Antennas: Why Size is Important for This Wireless Equipment

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In response to the recent FCC docket 10-153, many stakeholders proposed relaxing antennas requirements so as to allow the use of smaller antennas in certain circumstances. This is an increasingly important issue as tower rental costs can be as high as 62 percent of the total cost of ownership for a microwave solutions link. As these costs are directly related to antenna size, reducing antenna size leads to a significant reduction in the cost of ownership for microwave equipment links.

The Fixed Wireless Communications Coalition (FWCC), of which Aviat Networks is a major contributor, proposed a possible compromise that would leave Category A standards unchanged while relaxing Category B standards. The latter are less demanding than Category A, and after some further easing, might allow significantly smaller antennas. The rules should permit the use of these smaller antennas where congestion is not a problem, and require upgrades to better antennas where necessary.

A further detailed proposal from Comsearch proposed a new antenna category known as B2, which would lead to a reduction in antenna size of up to 50 percent in some frequency bands. This would be a significant cost saving for link operators.

At the present time, the industry is waiting for the FCC to deliberate on the responses to its 10-153 docket, including those on reducing antenna size.

See the briefing paper below for more information.

Ian Marshall
Regulatory Manager, Aviat Networks

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