Newly adopted and proposed fixed service rules add flexibility, especially in rural areas.
We wrote last summer about how the proliferation of wireless devices has created a corresponding need for wireless backhaul capacity – “backhaul” being a term that refers generally to the “middle mile” links that move end-user traffic between cell towers and the core network. Traditionally, backhaul was carried on copper wires or fiber, but that 20th Century approach isn’t necessarily the most practical, particularly in rural and remote locations. In those situations, a wireless approach, using point-to-point links on microwave frequencies allocated by the FCC for “fixed service”, does the trick better. The FCC has now adopted the proposals it put forth a year ago to facilitate the use of fixed service spectrum for wireless backhaul. In a concurrent notice of proposed rulemaking (NPRM), the Commission seeks comment on additional wireless backhaul matters.
During the meeting at which the Commission adopted the new rules, Chairman Genachowski admitted that when he first heard about the proposals to change the fixed service rules, his eyes “glazed over.” Now, however, the subject is generating a lot of enthusiasm at the FCC. At the meeting, Genachowski and the other Commissioners rhapsodized that more flexible fixed service rules will increase rural buildout, spur 4G deployment, create jobs, and stimulate technical innovation.
Specifically, the new rules will:
- Allow fixed service wireless into the 7 and 13 GHz bands currently occupied by broadcast auxiliary services (BAS) and cable TV relay service (CARS). Broadcasters and cable operators use BAS and CARS to transmit video programming, both over fixed links (e.g., from TV studio to transmitter) and through TV pickup operations (those news vans with telescoping antennas on top). While sharing among fixed users is feasible, mobile and fixed operations don’t mix as well. News gathering vehicles must respond to breaking news quickly, without stopping to formally coordinate with other spectrum users, while fixed service systems need protection from interference to assure a high level of reliability.
The FCC divided the baby along demographic lines: it authorized fixed service operations in the BAS and CARS bands only in areas that have no TV pickup licenses. That’s half of the nation’s land mass, but only 10% of its people. Allowing sharing in these areas may encourage rural buildout, as the FCC hopes, but will not go far to ease the congestion in urban areas caused by millions of data-hungry smartphones and tablets. The fixed wireless industry is therefore likely to continue exploring other workable spectrum arrangements, such as sharing with government spectrum at 7125-8500 MHz.
*** NOTE: If you’re a BAS or CARS licensee, make sure your information in ULS is correct, so that the Commission does not authorize an overlapping fixed service link. We have previously provided tips on how to do that here. The new rules also require registration of TV pickup receive stations. ***
Permit adaptive modulation. The Part 101 rules governing fixed service operation require a minimum payload capacity (in megabits per second) for fixed links. Sometimes, though, passing atmospheric conditions interrupt a signal at this data rate, a condition called a “fade.” The connection is lost and the system has to be resynchronized, which can take several minutes. The Fixed Wireless Communications Coalition (FWCC) asked the FCC to allow “adaptive modulation”, a process which temporarily slows the data rate during a fade so as to keep the connection intact. The FCC agreed, but with a catch: for efficiency, a fixed link using adaptive modulation must maintain the minimum payload capacity 99.95 percent of the time, or all but four hours of the year. This is a design requirement, not a performance requirement: links must be designed to comply, but the FCC will not require reporting of actual adaptive modulation use.
- Eliminate the “final link” rule. Broadcasters have generally been permitted to use fixed Part 101 fixed service stations as part of the process of delivering programming to their transmitters – provided, that is, that fixed service stations not be used as the final RF link in that process. The Commission has now re-thought that rule, concluding that there may be significant benefits to be realized from eliminating it, with no associated costs. Result: the “final link” rule is now history.
The FCC rejected a proposal to allow fixed service licensees to deploy smaller “auxiliary” transmitters, all sharing the same spectrum as the primary station and all located within that primary station’s coordinated service contour. Proponents claimed that this would lead to more efficient use, or re-use, of the spectrum. Not so fast, said the Commission, which wasn’t convinced that primaries and auxiliaries could really co-exist without causing interference . . . or that the spectrum isn’t already extensively re-used, and re-useable, under existing rules. Plus, the “auxiliary” proposal would create a “perverse” – that’s the Commission’s word, not ours – incentive for applicants to propose excessive power for their primary stations, since the bigger the primary contour, the more auxiliaries could be crammed into it. And anyway, a variety of other bands (think LMDS, 24 GHz and 39 GHz) already available could be used for the types of operations contemplated for “auxiliary” stations. Bottom line: a big negatory on the auxiliary proposal.
Finally, in the concurrent NPRM, the Commission has requested comment on:
- Allowing smaller Category B antennas in the 6, 18, and 23 GHz bands (three-foot, one-foot, and eight-inch antennas, respectively). Smaller antennas potentially cause more interference because they disperse energy more broadly, but are cheaper to manufacture, install, and maintain, and typically generate fewer zoning objections. There are no proposed changes to the more stringent Category A antennas, which are required wherever Category B antennas would cause interference.
- Exempting licensees from payload and loading requirements in non-congested (mostly rural) areas – specifically, in areas where Category B antennas are allowed. The goal is to lower costs and increase investment in rural broadband deployment. In congested areas, the Commission proposes exempting licensees that can make a special showing that: (a) the efficiency standard is preventing deployment; (b) there are no reasonable alternatives; and (c) relaxing the standard would result in tangible and specific public interest benefits.
- Allowing wider channels, or channel “stacking,” in the lower 6 and 11 GHz bands, as proposed by the FWCC. Where traffic demand is high, wider channels would result in lower costs, improved reliability, elimination of intermodulation issues, and increased spectrum utilization. The Commission seeks comment on allowing 60 MHz channels in the lower 6 GHz band and 80 MHz channels in the 11 GHz band.
- Revising waiver standards for microwave stations that point near the geostationary arc to conform to International Telecommunications Union (ITU) regulations.
- Defining the term “minimum payload capacity” as used in the efficiency standard rule. To accommodate application of the rule to Internet protocol radios, the Commission proposes rules, put forward by Comsearch, defining the term to include only capacity that is available to carry traffic, excluding overhead data used by the network itself, such as error correction and routing information.
The newly adopted rules will become effective 30 days after publication in the Federal Register. Check back here for updates on that front. Comments on the issues teed up in the NPRM are due on October 4, 2011, and reply comments on October 25.