Doug Lung /
08.12.2011 12:00 AM
FCC Approves Sharing of BAS Microwave Bands

At Tuesday's Open Commission Meeting the FCC adopted a Report and Order, Further Notice of Proposed Rulemaking and Memorandum Opinion and Order (FCC 11-120) allowing fixed service (FS) operations in the 6875-7125 MHz and 12700-13100 MHz broadcast auxiliary service (BAS) bands. While this sharing will complicate BAS operations in these bands, the impact is not nearly as bad as it would have been had the FCC adopted some of the more radical proposals in its Notice of Proposed Rulemaking. FS operations will be permitted only in rural areas where the band is not currently licensed to TV mobile pickup stations used in local news gathering operations. The FCC also did not permit FS licensees to coordinate and deploy "auxiliary" links which would effectively allow point-to-multipoint operations under point-to-point rules. Broadcasters will be required to register ENG receive sites.

"The record indicates that it is not feasible to allow FS to share spectrum with mobile and temporary fixed TV pickup operations in areas where mobile and temporary fixed TV pickup operations are licensed," the commission said in its Report and Order. "While BAS fixed and mobile operations share spectrum in the same geographic areas, the sharing that exists today would not be practicable if it were not guided by informal agreements among local market participants."

Referencing comments from Engineers for Integrity of Broadcast Auxiliary Service Spectrum EIBASS), the Report and Order notes that sharing among broadcasters works well "because they have an incentive to participate in mutually agreed shared coordination." It also notes, "Part 101 FS operators do not have the same incentive to accommodate the needs of TV pick-up operations, however, as few of them are involved in video newsgathering or video coverage of other live events." The Report and Order acknowledges that if FS operators were granted the same formal priority over TV pick-up operations, "FS operators could apply for spectrum that is presently used by TV pick-up operations—potentially precluding new TV pick-up operations and forcing existing operations to shut down."

Fortunately the FCC concluded that it is not "feasible at this time to adopt a formal band segmentation plan to separate fixed and mobile operations into designated sub-bands of the 7 and 13 GHz bands" as was requested by the Fixed Wireless Communications Coalition (FWCC) and Vislink, Inc. The FCC noted that the BAS and CARS bands support a mix of fixed, temporary fixed and mobile services, including airborne mobile, which are coordinated on an individual market, not national, basis. The FCC states, "Since we could not adopt a uniform band plan throughout the nation and provide the same spectrum to FS throughout the nation, the value of such band segmentation would be quite limited." The FCC retained the 25 MHz bandwidth in the 7 and 13 GHz BAS/CARS bands but allowed some flexibility to sub-divide the channels. FS operators can utilize 5, 8.33, and 12.5 MHz wide channels but not 10 and 30 MHz wide channels. FS operators can also combine two 25 MHz wide channels to obtain a 50 MHz wide channel. 50 MHz wide channels are not allowed in the 7 GHz due to the limited amount of spectrum in the band.

FS paths are not allowed to cross the service areas of TV pickup authorizations and FS operators must coordinate with all relevant licensees, including TV pickup authorizations, pursuant to the formal Part 101 coordination procedures. FS applicants are also required to coordinate with and protect fixed satellite service (FSS) licensees and applicants according to Part 101 rules.

If you are wondering what happens if there is a major news event in one of the rural areas where FS operation on BAS bands is allowed, the FCC said it would reserve two 25-MHz channels for BAS and CARS in the 7 GHz band (6975-7125 MHz) and two 25-MHz channels in the 13 GHz band (13150-13200 MHz) nationwide to "accommodate TV pickup stations covering events that occur outside the license areas of local BAS and CARS operations." The FCC rejected an additional condition requested by EIBASS and NAB that the newcomer FS station cannot degrade the noise threshold of any existing ENG-RO site by more than 0.5 dB

The Report and Order requires BAS TV pickup licensees to record their stationary receive-only sites in the FCC ULS database. This should be relatively easy for TV stations with limited area of operation. It may be difficult for BAS TV pickup licensees with licenses specifying a nationwide area of operation to list all receive sites, but in many cases these would be temporary receive sites, which do not have to be listed, or receive sites shared with local stations, which will be registered in ULS by the local station.

The Report and Order eliminated the "final link rule" which prevented broadcasters from using Part 101 licenses to deliver programming to their transmitter sites. The FCC notes that "With increasing adoption of digital technologies, the final link rule has become an outdated regulation that imposes unnecessary costs on broadcasters. In some instances, it may have required broadcasters to build two different, largely redundant, systems: one system to carry program material to the transmitter site and a separate system to handle other data. Eliminating the rule will provide tangible benefits to broadcasters by reducing unnecessary duplication of system and enabling them to operate more efficiently." I can see this opening opportunities for low power and potentially some full power operators to use 23 GHz for short studio-to-transmitter links in some areas where the path is too short for 7 GHz and 13 GHz frequencies are not available.

The Report and Order modifies other rules relating to FS operations, including use of adaptive modulation and its impact on reliability and minimum payload capacity for various channel sizes in certain Part 101 bands, The FCC adopted a 99.95 percent standard for reliability over the objections of Verizon, which asserted that a 99.95 percent standard would create improper incentives to use smaller and lower performance antennas, which would significantly decrease spectral efficiency and increase the deployment costs and interference to future microwave licensees.

The FCC is planning additional changes to the microwave rules, that are reflected in the Further Notice of Proposed Rulemaking (FNPRM) adopted with the Report and Order. These changes would impact antenna standards for pattern and gain, revising spectrum efficiency standards in rural areas, where lower traffic volume and greater distances may make it financially prohibitive to meet minimum capacity requirements, and allow wider channels in the 6 GHz and 11 GHz band.

A waiver filing is currently required for FS transmitters operating in the 2655-2690 MHz and 5925-7075 MHz bands with an antenna aimed within 2 degrees of the geostationary arc and for transmitters operating in the 12700-13250 MHz band with an antenna aimed within 1.5 degrees of the geostationary arc. Comsearch asked the FCC to amend Section 101.145 of the Rules to require a waiver filing for these stations only if the EIRP is greater than the values listed in the ITU Radio Regulations. The FCC seeks comment on these and other proposals in the FNPRM.

In my opinion the FCC has achieved a reasonable balance between protecting TV pickup operations in the 7 and 13 GHz band, at least in markets where such use is already licensed. Broadcasters will face more competition for fixed link STL and ICR paths. Broadcasters will need to make sure all existing links are properly licensed, including correct receive site location and emission type in order to prevent a properly filed and coordinated FS application from blocking any license changes. TV Pickup receive sites also need to be added to licenses in ULS. Not only is this now an FCC requirement, but unregistered receive sites will have trouble getting protection not only from in-band 7 and 13 GHz FS operations but from new services moving into spectrum adjacent to the 2 GHz BAS band.


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