5. The Commission also makes other minor changes and refinements to its rules for TV bands devices. With these changes and clarifications, the rules will better ensure that licensed services are protected from interference while retaining flexibility for unlicensed devices to share the TV bands with them.
Protection Criteria for Incumbent Services

TV Stations

6. In the Second Report and Order, the Commission adopted technical criteria for determining when a TV channel is considered vacant for the purpose of allowing operation of an unlicensed device on that channel. It protected full service TV stations and Class A TV, low power TV, TV translator and TV booster stations from interference within defined signal contours. The signal level defining a television station's protected contour varies depending on the type of station, e.g., analog or digital TV, and the band in which a TV station operates, e.g., VHF or UHF. The protected contours for analog TV stations are calculated in accordance with the F(50,50) curves specified in the Commission's rules, and the protected contours for digital TV stations are calculated in accordance with the F(50,90) curves. While part 74 of the rules protects low power stations to a higher signal strength contour, and therefore to a shorter distance, than full service TV stations, the Commission decided to require TV bands devices to protect low power stations to the same contour as full service TV stations.

7. Decision. The Commission affirms its decisions regarding the protection contours for TV stations. First, the Commission declines to change the method that must be used to calculate TV station protected contours. No party has described an alternative model that will provide more accurate calculations of TV station contours than the Commission's current method. The current method of calculating TV station contours in Sec. 73.684 of the rules using the FCC curves in Sec. 73.699 of the rules is straightforward, well understood and has proven sufficiently accurate over time. Given the lack of compelling information to the contrary, the Commission believes that calculations of channel availability relying on that methodology will provide satisfactory protection of TV services. Further, with respect to Adaptrum's request that TV signal information be incorporated into the TV bands databases, the Commission is removing the requirement that TV bands devices that include a geolocation capability and access to a database must sense television and low power auxiliary stations. Thus, sensing information on the location of TV signals would not be available to incorporate into the database. The Commission agrees with Rudman/Ericksen that the TV bands device database should include information on transmit antenna beam tilt to permit TV contour calculations to be made consistent with part 73 of the rules and is modifying Sec. 15.713(h) of the rules accordingly.

8. The Commission also affirms its decision to protect low power television stations to the same signal contour as full service TV stations. Low power stations may provide the only overtheair broadcast services in rural areas, and the Commission disagrees that viewers of those stations should receive less protection than viewers of full service stations. Further, low power stations by their nature cover only a relatively small area, so a modest increase in the protected area beyond the defined part 74 contour for these stations will not significantly impact the deployment of TV bands devices.

9. The Commission disagrees with SBE and Community Broadcasters that the rules fail to protect analog TV stations. While the D/U protection ratios for analog TV stations are higher than for digital stations, the protected service contours for analog stations are also higher than for digital stations. The net result is that the level of an undesired signal from a TVBD that will cause interference to an analog station is higher than the level that will cause interference to a digital station. Thus, the Commission's standards for protection of digital TV stations from
[[Page 75816]]
interference caused by TVBDs when applied for protection of analog TV stations provide somewhat greater protection of analog TV stations than would standards produced from a similar analysis that specifically considered protection of analog TV stations. The Commission also finds that an analysis focusing on digital operation is appropriate for low power television stations because these stations will eventually convert to digital operation.

10. The Commission declines to adopt any new requirements related to the use of TV bands devices in close proximity to amplified indoor antennas. A TV bands device and a TV receiver in close proximity would be under the control of the same party who could take steps to eliminate interference. The Commission previously adopted a requirement in the Second Report and Order requiring manufacturers to provide information to consumers on possible methods to resolve interference to television in the event it occurs, so the Commission finds no need to adopt any additional requirements.
Wireless Microphones and Other Low Power Auxiliary Stations

11. In the Second Report and Order, the Commission decided that the locations where licensed part 74 low power auxiliary stations, including wireless microphones, are used can be registered in the TV bands device database and will be protected from interference from TV bands devices. TV bands devices may not operate cochannel to a registered low power auxiliary station within a distance of 1 kilometer of the registered coordinates.

12. Decision. The Commission continues to recognize that wireless microphones are currently used in many different venues where people gather for events large and small and many consumers and businesses have come to rely on these devices. The Commission has previously limited use of channels 2 and 520 to communications between fixed TVBDs and reserved two channels in the range 1451 in the 13 markets where PLMRS and CMRS systems operate to make sure that frequencies are available for wireless microphones. The Commission herein expands the reservation of two channels in the range 1451 to all markets nationwide as suggested by several petitioners. This will provide frequencies where a limited but substantial number of wireless microphones can be operated on any basis without the potential for interference from TV bands devices. It will also ensure that frequencies are available everywhere for licensed wireless microphones used on a roving basis to operate without risk of receiving harmful interference from TVBDs. The Commission has also provided for a nominal separation distance between TVBDs and sites of venues and events where large numbers of unlicensed wireless microphones used by permitting such sites to be registered in the TV bands databases. Further, it notes that at any particular location a number of TV channels will not be available for use by TVBDs due to the application of the various interference protection requirements under our rules. Thus, a significant amount of spectrum will be available on which wireless microphones can be operated as they have in the past without concern for interference from TVBDs. The Commission believes that this spectrum will provide sufficient frequencies to support wireless microphone operations at the great majority of events. The Commission disagrees with those who argue that more spectrum should be reserved for wireless microphones. It observes that wireless microphones generally have operated very inefficiently, perhaps in part due to the luxury of having access to a wealth of spectrum. While there may be users that believe they need access to more spectrum to accommodate more wireless microphones, the Commission finds that any such needs must be accommodated through improvements in spectrum efficiency. The Commission underscored this point in the currently pending wireless microphone proceeding and sought comment on solutions that could enable wireless microphones to operate more efficiently and/or improve their immunity to harmful interference, See Report and Order and Further Notice of Proposed Rule Making in WT Docket Nos. 08166 and 08167 and ET Docket No. 1024, 25 FCC Rcd 643, 702 (2010), FCC 1016, 75 FR 9113, March 1, 2010. The Commission will continue to pursue this issue as it considers possible repurposing of the TV spectrum.

13. The Commission disagrees with the petitioners that argue unlicensed wireless microphones should be subject to the same requirements as TVBDs under the rules. There are many important differences that make it impractical to apply the same rules to both types of devices. For example, TVBDs are expected to be data devices that will have access to the Internet. Wireless microphones do not typically include geolocation technology nor do they connect to the Internet, so requiring these devices to check for channel availability through a database would be impractical. Also, TVBDs generally should be able to tolerate some latency, whereas wireless microphones operate in real time and generally cannot tolerate significant latency. Most importantly, unlicensed wireless microphones have been operating for quite some time without causing harmful interference. Accordingly, the Commission concludes that unlicensed wireless microphones should not be subject to the more confined approach it has applied to TVBDs.

14. With regard to registration of unlicensed devices in the TV bands databases, the Commission first observes that unlicensed wireless microphones operate under the same general conditions of operation in Sec. 15.5 of the rules as TV bands devices, meaning they may not cause interference to authorized services and must accept any interference received, including interference from other nonlicensed devices. As a general matter, the Commission therefore finds that it would be inappropriate to protect unlicensed wireless microphones against harmful interference from other unlicensed devices, and in particular TV bands devices. The Commission observes that there are a wide variety of applications for wireless microphones ranging from a single wireless microphone used by a performer or presenter, to small theatrical productions using perhaps 1020 microphones, to large scale productions and events such as professional sports events and Broadway style productions that may use well over 100 wireless microphones. The overwhelming majority of such use does not merit registration in the TV bands database. In cases where the number of wireless microphones needed for an event is relatively low, the operator of unlicensed microphones can avoid receiving harmful interference from TVBDs by simply using the reserved channels or other channels in each market where TVBDs are not allowed to operate. The two reserved TV channels will accommodate a minimum of at least 16 wireless microphones, and the additional channels that are not available for TVBDs at most locations will accommodate many additional wireless microphones. On the other hand, the Commission recognizes that certain events, such as major sporting contests or live theatrical productions/shows, may use scores of wireless microphones and therefore may not be able to be accommodated in the two reserved channels and other channels that may be available for wireless microphones at that location.

[[Page 75817]]

15. Accordingly, the Commission is addressing unlicensed wireless microphones and low power auxiliary devices in our rules for TV band devices as follows. As the general rule, it is not allowing unlicensed wireless microphones and other low power auxiliary devices operating without a license to be registered in the database; these devices will not be afforded protection from interference from TV bands devices on channels where TV bands devices are allowed to operate. Entities desiring to operate wireless microphones on an unlicensed basis without potential for interference from TVBDs may use the two channels in each market area where TVBDs are not allowed to operate, as well as other TV channels that will be available in the vast majority of locations. Such entities may consult with a TV bands database to identify the reserved channels at their location, as well as the TV channels that may not be available for TV band devices. Entities operating or otherwise responsible for the audio systems at major events where large numbers of wireless microphones will be used and cannot be accommodated in the available channels at that location may request registration of the site in the TV bands databases. The registration requests must be filed with the Commission. Entities filing registration requests will be required to certify that they are using the reserved channels and all other available channels from 751 (except channel 37) that are not available for use by TV band devices and are practicable for use by wireless microphones. The request to be registered must be filed with the Commission at least 30 days in advance and include the hours, dates or days of the week and specific weeks on which those microphones will be in actual use (on dates where events are not taking place, those sites will not be protected) and other identifying information also required of low power auxiliary licensees. Unlicensed microphones at event sites qualifying for registration in TV bands databases will be afforded the same geographic spacing from TVBDs as licensed microphones. The Commission also advises entities responsible for event sites qualifying for registration in TV bands databases that registration does not create or establish any form or right or assurance of continued use of the spectrum in the future.

16. To allow it to better identify registered wireless microphone licensed operations and unlicensed sites, the Commission adopted the following registration procedures. Operators of licensed wireless microphones may register sites directly with one of the designated database administrators and provide the information required by the rules, which the Commission is amending to include the wireless microphone call sign. As indicated, operators of venues using unlicensed wireless microphones will be required to register their sites with the Commission, which will transmit the information to the TV bands device database administrators. For the purpose of this registration, the Commission will develop a form that will allow the information to be filed through one of the Commission's electronic filing systems, such as the Universal Licensing System (ULS). The applicant will be required to certify that it complies with the requirements for registration of unlicensed wireless microphones, including that it will first make use of all TV channels not available for TV bands devices that are practicable for wireless microphone use, including channels 751 (except channel 37), and submit the information specified by the rules, which we are amending to include the name of the venue where the equipment is operated. As a benchmark, at least 68 wireless microphones must be operating in each channel that is being used for the event. Registration requests that do not meet these criteria will not be registered in the TV bands databases. The Commission will take actions against parties that file inaccurate or incomplete information, such as denial of registration in the database, removal of information from the database pursuant to Sec. 15.713(i), or other sanctions as appropriate to ensure compliance with the rules. The Commission will make requests for registration of sites that use unlicensed wireless microphones public and will provide an opportunity for public comment or objections. The Commission has delegated authority for administering this registration process jointly to its Office of Engineering and Technology and Wireless Telecommunications Bureaus.

17. The Commission is maintaining the requirement that fixed TV bands devices may not operate cochannel with low power auxiliary stations within 1 km of their coordinates registered in the TV bands databases. The Commission recognizes the arguments of Shure and CWMU about the difference in power levels between fixed TV bands devices and wireless microphones. However, whether harmful interference occurs in a particular situation depends on many factors, including the undesired signal power, antenna directivity and separation distance, as well as the level of the desired signal at the receiver, the receive antenna and receiver characteristics, and any intervening structures or terrain that could attenuate the undesired signal. Neither Shure nor CWMU provided an analysis with their petitions demonstrating that the 1 km separation distance adopted in the Second Report and Order is inadequate for fixed devices when taking all relevant factors into account. In cases where licensed low power auxiliary stations are being used at large outdoor venues, such as racetracks or golf courses, the Commission will permit the party registering the devices to specify the coordinates of multiple locations within the site to ensure that protection is provided over the entire facility where microphones are being used.

18. However, the Commission agrees with petitioners that argue that it is not necessary to provide low power auxiliary stations the same protection from personal/portable TV bands devices because the latter operate with power levels at least forty times lower than the maximum power permitted for fixed TV bands devices. Therefore, it is modifying the rules to require that Mode II (independent) personal/portable devices not operate cochannel with low power auxiliary stations within 400 meters (0.4 km) of their coordinates registered in the TV bands device database. A 100 mW transmitter will produce a lower signal at 400 meters than a 4 watt transmitter at 1 km using a free space calculation, so this shorter distance will provide greater protection for low power auxiliary devices from 100 mW TV bands devices than a 1 km separation from 4 watt devices. The Commission will use this same 400 meters distance for personal/portable devices that operate with less than 100 mW of power.

19. The Commission finds that it is not practical to protect wireless microphones using information obtained from the ULS and declines to require that that information be used in defining such protection as suggested by Rudman/Ericksen. Some wireless microphones are licensed using specific coordinates, while others are licensed to a wide area such as the entire service area of a TV station, and a license may specify multiple operating channels. The Commission also observes that wireless microphones can be operated intermittently at discrete locations, rather than continuously over a wide area. Thus, the use of ULS licensing data could preclude TV bands devices from operating on multiple channels and at locations where no wireless microphones are in operation.
[[Page 75818]]
Translators, Cable Headends and Multichannel Video Program Distributors

20. In the Second Report and Order, the Commission adopted rules to protect TV translator receive sites and cable TV headends that are located outside the protected contours of the TV stations being received. TV translator receive sites are often located on high towers or at high elevations and use high gain antennas to receive a full service station's signal well beyond the station's service area. Cable headends are facilities that acquire and distribute video service signals over a cable television system. Broadcast TV signals are often received offtheair at a cable headend for retransmission over the cable system. In many cases, the cable headend will use an antenna with high gain antenna mounted high on a tower to receive a TV station's signals well beyond the station's service area in a manner similar to that used by TV translators. The Commission found that it is important to avoid disruption of TV service to viewers who are located beyond TV station service areas and able to receive those signals through retransmission on TV translators and cable systems. While those viewers are in fact located beyond the areas where the Commission normally protects TV services, in these cases TV services have de facto been extended and valuable service is being provided to a significant number of households. If a TV bands device were to be located between the TV translator/cable headend and TV station and then operate on one or more of the channels being received by those facilities in a manner that results in harmful interference, TV reception to the households and the cable system services could be disrupted.

21. To protect cable headends and TV translator receive sites which are not listed in Commission databases, the Commission allowed operators of TV translator receive sites and cable headends that are located within 80 km of the service contour of the received TV station to register their location and the channel(s) they receive in the TV bands device database. To prevent unnecessary entries into the database, the Commission permitted translator receive sites and cable headends to be registered only if they are outside the protected contour of the TV station being received. The rules limit operation of TV bands devices cochannel and adjacent to the channel(s) being received over an arc of 30 degrees from a line between the receive site and the TV station(s) being received. Within this arc, TV bands devices operating cochannel to the received station may not operate within 80 km of the receive site, and TV bands devices on channels adjacent to the received station may not operate within 20 km of the receive site. The protection radius extends only as far as the protected contour of the station being received, so the cochannel protection distance would be less than 80 km for receive sites closer than this distance from a protected contour, and both the cochannel and adjacent channel protection distances would be less than 20 km for receive sites closer than this distance from a protected contour. In addition, to prevent interference to TV translators and cable headends from TV bands devices outside the main beam of the receive antenna, the Commission prohibited TV bands devices from operating cochannel to the channel(s) being received by these facilities within 8 kilometers and from operating on adjacent channels within 2 kilometers in all directions off the 30 degree arc.

22. Decision. The Commission modified the rules to expand and more clearly define the types of receive facilities that may be registered in the TV bands database and are making certain changes to the protection criteria for these receive facilities. The purpose of permitting the registration of receive sites is to protect the reception of overtheair TV signals that are redistributed through another means. Consistent with this intent, the Commission will permit the registration of TV receive sites for other types of video service providers besides cable systems and is modifying the rules in this regard to more clearly and completely define the types of facilities that may be registered. The Commission therefore specifies that receive sites of all multichannel video programming distributors (MVPDs) as defined by section 602(13) of the Communications Act may be voluntarily registered in the database, in addition to TV translator receive sites.

23. The Commission recognizes that there are cable headends that receive TV station signals located at distances beyond 80 km from the edge of a television station's protected service contour and understand NCTA's concern for possible disruption service to cable subscribers. These same considerations would apply to other MVPDs and to TV translator, low power TV and Class A TV stations that retransmit programming from another TV station. The Commission does not believe that the requested change would have significant impact on the availability of TV white space because these facilities are generally in remote areas where many channels will be available for white space devices. However, the Commission also recognizes that parties may wish to have an opportunity to review such requests to confirm the assessment. We are therefore providing that current MVPD operators, TV translator, low power TV and Class A TV stations with receive sites located beyond the 80 km cochannel protection distance in the rules may apply for a waiver of that distance during a period that will end 90 days after the effective date of the rules adopted herein. Such waiver requests would also involve shifting the 20 km adjacent channel protection distance so that it is measured from the actual receive site. The Commission will then issue a public notice requesting comment on requests it receives and issue decisions. MVPD operators and TV translator, low power TV and class A TV stations that commence operation in the future with receive sites located beyond the co channel and adjacent protection distances may apply for a waiver of those distances within 90 days of commencing operation. Following receipt of such request(s), the Commission will then issue a public notice asking for comment on the request(s) and issue decision(s).

24. The Commission declines to increase the width of the 30 degree protected arc as requested by NCTA. A receive site located outside the protected contour of a TV station would need to incorporate a high gain receive antenna, which has a narrow beamwidth. While it recognizes NCTA's argument that an antenna has side lobes that will allow it to receive signals outside its main beam, this does not in itself demonstrate that the current protection requirement is inadequate or that a wider protected arc is necessary. Adaptrum provides no information to support its argument that the protection distance outside of the main lobe of the receive antenna should be significantly reduced and we therefore deny that request. The Commission further declines to require operators of fixed TV bands devices to coordinate with operators of receive sites. The requirements it has adopted are extremely conservative and will adequately protect receive sites, so a coordination requirement is unnecessary and would be cumbersome to implement.

25. The Commission finds it unnecessary to provide for registration of receive sites within the protected contour of a TV station being received and thus declines to allow such registrations. Within a station's protected service contour, receive sites are protected from interference by the
[[Page 75819]]
same provisions that protect reception by consumers. The rules require that TV bands devices be located outside the contour of a cochannel TV station, so a TV bands device located near a contour that is communicating with another TV bands device would not be directing its signal into the contour where the receive site is located. Further, a receive site inside, but near the edge of a protected contour, would have it receive antenna directed toward the TV station and not at the TV bands device outside the contour. Therefore, the orientation of the antennas in this situation makes interference highly unlikely. Additionally, a TV bands device operating on a channel adjacent to an occupied TV channel is permitted to operate within the service contour, but at a lower power level not to exceed 40 mW. This lower power level combined with the fact that a receive site within a contour will receive a higher signal level than a receive site outside the contour makes adjacent channel interference from that source again unlikely. Furthermore, in the event that interference does occur, the operator of the TV bands device is required to cease operation.

26. Finally, the Commission is modifying the text of the rules to clarify that registration for receive sites is limited to channels that are received overtheair and are used as part of service of the MVPD, TV translator, low power TV station or Class A TV station. The Commission is not limiting registration to local channels so as not to preclude the possibility that an MVPD or TV translator/low power television station may retransmit outofmarket channels if it is authorized to do so.
TV Bands Devices

Spectrum Sensing

27. In addition to requiring that TV bands devices access a database to determine available channels, the Commission decided in the Second Report and Order to require that TV bands devices be capable of sensing analog TV signals, digital TV signals and wireless microphone signals at a level of 114 dBm within defined receiver bandwidths. This level is referenced to an omnidirectional receive antenna with a gain of 0 dBi. If a receive antenna with a minimum directional gain of less than 0 dBi is used, the detection threshold must be reduced by the amount in dB that the minimum directional gain of the antenna is less than 0 dBi. Alternative approaches for the sensing antenna are permitted that provide at least the same performance as an omni directional antenna with 0 dBi gain. The Commission also required that the receive antenna used by fixed devices be located at least 10 meters above the ground to maximize the likelihood that its reception is not blocked from receiving signals originating from any direction. It found that receive antenna height requirements are impractical for personal/ portable devices and declined to impose such requirements on those devices.

28. Under the rules adopted in the Second Report and Order, a TV bands device is permitted to begin operating on a TV channel if no wireless microphone or other low power auxiliary device signals above the detection threshold are detected within a minimum time interval of 30 seconds. A TV bands device must also perform inservice monitoring of channels on which it operates a minimum of once every 60 seconds. There is no minimum channel availability check time for inservice monitoring. If a device detects a wireless microphone or other low power auxiliary device signal on a channel it is using, the device must cease all transmissions on that channel within two seconds. If a TV signal is detected on a channel indicated as available for use by the database, the TV bands device must provide a notice of that detection to the operator of the device and provide a means for the operator to remove the channel from the device's list of available channels. However, with respect to TV signals, the database is the controlling factor in determining whether a channel is available, and there is no requirement for a TV bands device to avoid operating on a channel where it detects a TV signal, since it is possible to detect a signal outside a station's protected service contour.

29. A personal/portable device operating in Mode I must identify (report) those TV channels on which it senses a wireless microphone or television signal above the detection threshold to the fixed or Mode II personal/portable device that provides it with a list of available channels. The fixed or Mode II device must respond as if it had detected the signal itself, i.e., it must not use the occupied channel if the Mode I device detects a wireless microphone and must report the TV signal detection to the operator of the device. In addition, TV bands devices communicating either directly with one another or linked through a base station must share information on channel occupancy determined by sensing. If any device in a local area group or network determines that a channel is occupied and notifies other devices with which it is linked, all the other linked devices will be required to respond as if they had detected the signal themselves.

30. Decision. The Commission eliminated the requirement for TV bands devices that rely on geolocation and database access to sense analog and digital TV signals and also wireless microphones and other low power auxiliary stations. Much of this proceeding has focused on the central question of whether spectrum sensing is a viable tool for providing access to spectrum. The Commission has noted the benefits and limitations of spectrum sensing through testing conducted by its engineers and extensive discussion in the Second Report and Order. The Commission continues to believe that spectrum sensing will continue to develop and improve. It anticipates that some form of spectrum sensing may very well be included in TVBDs on a voluntary basis for purposes such as determining the quality of each channel relative to real and potential interference sources and enhancing spectrum sharing among TVBDs. However, at this juncture, the Commission does not believe that a mandatory spectrum sensing requirement best serves the public interest. As petitioners and responding parties indicate, the geo location and database access method and other provisions of the rules will provide adequate and reliable protection for television and low power broadcast auxiliary services, so that spectrum sensing is not necessary. With respect to protection of television services, the Commission observes that the geolocation and database method is already the primary means for preventing interference to TV stations. The sensing requirement adopted in the Second Report and Order only requires that a TV bands device inform the user when a TV signal above a threshold is detected and provide an opportunity for the user to change channel, but it does not preclude operation on a channel where a TV signal is detected. That is, the Second Report and Order essentially relied on geolocation and the TV bands databases to protect overthe air TV broadcasting, not spectrum sensing.

31. The Commission also now concludes that inclusion of a spectrum sensing capability is not necessary to protect wireless microphone operations. Parties operating part 74 licensed low power auxiliary stations at fixed locations are eligible to register those operations in the TV bands device database to obtain interference protection from TV bands devices. As indicated, for parties ineligible for part [[Page 75820]]
74 licensing, the Commission, in its Wireless Microphone R&O/FNPRM permitted the operation of low power auxiliary service stations on an unlicensed basis under part 15 of the rules pending a final decision on its proposals to expand eligibility for part 74 licensing and to allow a new category of wireless audio devices to operate in the core TV bands under part 15. Based on the Commission's informal observations of the marketing and uses of wireless microphones, it appears that the number of wireless microphones operating under the part 15 waiver significantly outnumbers those operating as part 74 licensed devices. Unlicensed devices operate on a noninterference basis, meaning they may not cause interference to authorized services, and must accept any interference received, including interference from other unlicensed devices such as TV bands devices. Requiring TV bands devices to sense low power auxiliary stations such as wireless microphones would inappropriately give interference protection to a large number of other unlicensed, unprotected devices because there is no way for the sensing feature of a TV bands device to distinguish licensed from unlicensed devices. The Commission recognizes that there will be some licensed low power auxiliary stations that can be used in roving applications for which the location cannot be known in advance and therefore cannot be registered in the TV bands device database. The Commission has reserved two channels at all locations on which unlicensed TV bands devices will not be allowed to operate in order to ensure that there are frequencies on which licensed microphones used in roving applications such as electronic news gathering can operate. The availability of the frequencies in these channels will make it unnecessary to provide special protection from interference for such applications.

32. With the elimination of the spectrum sensing requirement for TV bands devices that use geolocation and database access, there is collaterally no longer a need for a minimum receive antenna height for fixed devices, and the Commission consequently is removing that requirement from the rules. The Commission also revised and amended certain elements of the rules so that they continue to provide comparable assurance of protection against interference in the absence of sensing capabilities and to clarify and simplify the rules as they pertain to interference protection. In addition to revisions of the geolocation and database access rules, the changes include revision of certain terms used in the rules and elimination of the terms ``client device,'' ``client mode,'' ``master device,'' and ``master mode.''

33. As part of these changes, the Commission eliminated the requirements for devices operating in Mode I to use distributed sensing. It also observes that some of the comments on this issue appear to reflect an understanding that the rules permit extensive networks of devices that would all be linked together using a commonly identified list of available channels. The Commission wishes to correct any misconceptions that, at least at this stage, the rules contemplate or permit such networks and sharing of channel availability information. Rather, as stated in the Second Report and Order, the Commission will permit personal/portable TVBDs to be used in the operation of networks only where a means is provided to ensure that each device is operating consistent with the channels available at its particular location. The rules do not permit personal/portable devices operating in Mode I to relay channel availability information from one Mode I device to another Mode I device unless some means is used to ensure that each device is operating within the parameters for its particular location.

34. The Commission's elimination of the general requirement that all TV bands devices perform spectrum sensing at least once per minute and report channel availability information to other devices in a network removes the only existing requirement in the rules for a Mode I device to maintain contact with a fixed or Mode II device. In reviewing this provision, the Commission also observed that the rules currently do not require that a Mode I device periodically reestablish its list of available channels through either device that uses geolocation and database access; however, such rechecks for channel availability are necessary to ensure that a Mode I device does not continue to operate on a channel that becomes unavailable. To address these concerns, the Commission is adding a requirement that a device operating in Mode I must either receive a special signal from the Mode II or fixed device that provided its current list of available channels to verify that it is still in reception range of that device or contact a Mode II or fixed device at least once per minute to reverify/reestablish channel availability. This new requirement, including the special signal for verifying contact with the Mode II or fixed device that provided the Mode I device's list of available channels, is described in more detail in the section below on Recheck Procedures. This requirement is necessary because a Mode I device is not generally expected to be able to determine when it has moved, and it could possibly be moved to a location where the operating channel is occupied. Maintaining regular contact with a Mode II or fixed device will ensure that Mode I devices operate only on channels available at their location and that they cease operation when they move out of range of the device from which they obtained their list of available channels, in which case their list of available channels would no longer be valid. This requirement will also address situations where a Mode I device is no longer able to maintain contact with an operating fixed or Mode II device (for example, if the fixed or Mode II device with which the Mode I device has been communicating ceases operation and the Mode I device is not able to contact a replacement).

35. In reviewing the rules in this context, the Commission also observes that Sec. 15.711(b)(3)(ii) of the rules requires that a Mode II personal/portable device access the database for a list of available channels each time it is activated from a poweroff condition and re check its location and the database for available channels if it changes location during operation. It is the Commission's intent that a Mode II device monitor its location regularly to determine if its location has changed under this requirement. The Commission therefore amended this section of the rules to clarify that a Mode II device must use its geolocation capability to check its location at least once every 60 seconds, except when in ``sleep mode,'' i.e., in a mode in which the device is inactive but is not powereddown. This
clarification will ensure that Mode II devices recheck their list of available channels within a short interval if their location changes. It will also provide clarity with respect the recheck requirements for devices that operate on a mobile basis within a bounded geographic area in which the same channels are available at all locations.

36. While the Commission eliminated spectrum sensing for TVBDs that use geolocation and database access, it continues to believe that this technology offers significant promise for improving spectrum access and efficiency both in the TV bands and in providing access to other spectrum. Spectrum sensing has come a long way and some have expressed the view that even today it is sufficiently developed that it can be [[Page 75821]]
relied upon for determining access to the TV bands and other spectrum. The Commission is therefore leaving open the opportunity to submit applications for certification of sensingonly devices. It acknowledges that the process for approval of such devices is rigorous. However, the Commission continues to believe that an open and transparent review as provided by that process is appropriate for sensingonly devices. Accordingly, the Commission retained the provisions in the rules that permit the authorization and operation of personal/portable TV bands devices that rely on sensing alone under a ``proofofperformance'' standard. The Commission invites parties that submit such applications when they are ready to do so. The Commission takes this opportunity to clarify that devices that use sensing alone may initiate and participate in a network of TVBDs and may communicate with fixed, Mode I, Mode II and other sensingonly TVBDs but may not provide a Mode I device with a list of available channels. The Commission is also re locating the existing spectrum sensing technical provisions that previously applied to all TVBDs into the rule section on sensingonly devices.

37. The Commission is also increasing the minimum required detection threshold for wireless microphones and other LPAS stations of sensingonly devices from 114 dBm to 107 dBm. It is making this change for two reasons. First, sensingonly devices must operate with lower power than fixed or other personal/portable devices (except for personal/portable devices operating on channels adjacent to television stations), so a higher detection threshold would provide a level of protection that is approximately comparable to a lower threshold in a higher power device. Second, the rules for such devices specify that although compliance with the detection threshold for spectrum sensing is required, it is not necessarily sufficient for demonstrating reliable interference avoidance. Thus, the required detection threshold we are adopting serves as a minimum performance criteria for a device.

38. Authorization of a sensing only TVBD under the proofof performance standard also requires that a manufacturer submit a prototype device that will be tested by the Commission to ensure that the device is capable of operating without interference prior to certification. The decision on whether to certify a sensingonly device will be based on its performance, and in particular its ability to reliably detect the presence of authorized transmissions. If the Commission determines through testing that a lower detection threshold is necessary to prevent interference then it will require the device to meet the lower threshold before it could be certified. The Commission believes that these requirements for sensingonly devices are sufficiently conservative to prevent interference to TV reception and low power auxiliary stations. The Commission sees no basis for increasing the threshold for sensing of television signals. Technical Requirements

Antenna Height

39. Because the range at which a TV bands device can cause interference increases as the height of the device's antenna increases, the Commission adopted a maximum antenna height limit of 30 meters above ground for fixed devices. This height limit was intended to balance unlicensed fixed TV bands device transmission range with the distance at which those operations could impact licensed services. The Commission did not impose height restrictions on personal/portable devices because it found that it is not practical to administer an antenna height limit for those devices and the lower power and limited antenna gain of personal/portable devices would generally result in propagation over a shorter range than fixed devices. Further, the Commission observed that personal/portable devices, unlike fixed devices which have gain antennas mounted outdoors to maximize the propagation range of their signals, will likely typically be used indoors where their signals will be attenuated by exterior walls. These factors will significantly reduce the range at which signals from a personal/portable device will be of sufficient field strength to cause interference.

40. Decision. The Commission declines to increase the maximum permitted transmit antenna height above ground for fixed TV bands devices. As the Commission stated in the Second Report and Order, the 30 meters above ground limit was established as a balance between the benefits of increasing TV bands device transmission range and the need to minimize the impact on licensed services. Consistent with the Commission's stated approach in the Second Report and Order of taking a conservative approach in protecting authorized services, it finds the prudent course of action is to maintain the previously adopted height limit. If, in the future, experience with TV bands devices indicates that these devices could operate at higher transmit heights without causing interference, the Commission could revisit the height limit.

41. While the Commission expects that specifying a limit on antenna height above ground rather than above average terrain is satisfactory for controlling interference to authorized services in the majority of cases, it also recognizes petitioners' concerns about the increased potential for interference in instances where a fixed TV bands device antenna is located on a local geographic high point such as a hill or mountain. In such cases, the distance at which a TV bands device signal could propagate would be significantly increased, thus increasing the potential for interference to authorized operations in the TV bands. The Commission therefore concludes that it is necessary to modify our rules to limit the antenna HAAT of a fixed device as well as its antenna height above ground. In considering a limit for antenna HAAT, the Commission needs to balance the concerns for long range propagation from high points against the typical variability of ground height that occurs in areas where there are significant local high pointsthe Commission does not want to preclude fixed devices from a large number of sites in areas where there are rolling hills or a large number of relatively high points that do not generally provide open, lineof sight paths for propagation over long distances. The Commission finds that limiting the fixed device antenna HAAT to 106 meters (350 feet), as calculated by the TV bands database, provides an appropriate balance of these concerns. It will therefore restrict fixed TV bands devices from operating at locations where the HAAT of the ground is greater than 76 meters; this will allow use of an antenna at a height of up to 30 meters above ground level to provide an antenna HAAT of 106 meters. Accordingly, the Commission specifies that a fixed TV bands device antenna may not be located at a site where the ground HAAT is greater than 75 meters (246 feet). The ground HAAT is to be calculated by the TV bands database using computational software employing the methodology in Sec. 73.684(d) of the rules to ensure that fixed devices comply with this requirement.

42. In reexamining this issue, the Commission also notes that the rules currently do not indicate that fixed device antenna heights must be provided to the database for use in determining available channels. It was clearly the Commission's intent that fixed devices include their height when
[[Page 75822]]
querying the database because the available channels for fixed devices cannot be determined without this information. The Commission is therefore modifying Sec. Sec. 15.711(b)(3) and 15.713(f)(3) to indicate that fixed devices must submit their antenna height above ground to the database.

43. The Commission continues to decline to establish height limits for personal/portable devices. As the Commission stated in the Second Report and Order, there is no practical way to enforce such limits, and such limits are not necessary due to the different technical and operational characteristics of personal/portable devices.

Power and Power Spectral Density Limits

44. In the Second Report and Order, the Commission allowed fixed TV bands devices to operate with a peak transmitter output power of one watt with a maximum antenna gain of 6 dBi, and required that the transmitter power be reduced by the same amount in dB that the maximum antenna gain exceeds 6 dBi. This allows unlicensed TV bands fixed devices to operate with the equivalent of 4 watts EIRP. The Commission found that 4 watts EIRP is sufficient to allow fixed devices to communicate at ranges that will serve community and rural users while minimizing the potential for interference to broadcast television and other authorized services in the TV bands. Fixed TV bands devices were not permitted to operate adjacent to occupied TV channels, although the Commission decided to defer a final decision on this issue and to keep the record open pending the development of additional information demonstrating that a reliable method can be developed to allow adjacent channel operation while protecting authorized services.

45. The Commission allowed personal/portable TV bands devices to operate with a peak transmitter output power of 100 mW with a maximum antenna gain of 0 dBi, and required that the transmitter power of such devices be reduced by the same amount in dB that the maximum antenna gain exceeds 0 dBi. This allows personal/portable TV bands devices to operate with an equivalent of 100 mW EIRP. In cases where a personal/ portable device is operating adjacent to an occupied TV channel, the maximum permitted EIRP is 40 mW. Personal/portable devices that rely on spectrum sensing without the use of geolocation and a TV bands device database may be authorized at a power level up to 50 mW EIRP. The Commission did not specify minimum bandwidth limits for transmissions by TV bands devices or power spectral density (PSD) limits in the Second Report and Order.

46. Decision. The Commission is not convinced by the petitions for reconsideration that the power limits for unlicensed TV bands can be increased without also increasing the potential for interference to authorized services and is therefore affirming the power limits for fixed and personal/portable devices that it adopted in the Second Report and Order. In addition, the Commission does not find that the power level of TV bands devices should be restricted to protect against direct pickup interference to cable and satellite TV services. The Commission does, however, recognize the need to address power considerations in TV bands device signals that occupy less than the full bandwidth of a TV channel and is therefore amending the rules to include power spectral density limits.

47. The Commission declines to increase the 4 watt EIRP power limit for fixed devices and notes that it also considered and rejected a higher power limit for fixed devices in the Second Report and Order. While the Commission previously observed that there are advantages to higher power levels for fixed devices, such as reduced infrastructure costs and increased service range, it did not adopt a higher power limit due to concerns about increased risk of interference in congested areas and a lack of experience with unlicensed wireless broadband operations in the TV bands. The Commission also recognizes the increased range provided by operation at higher power levels would be particularly desirable for some applications, including rural service and mobile operations as suggested by Motorola. The Commission also understands that there may be situations where radio communications facilities could operate at higher power in TV white spaces without causing interference. However, the Commission continues to conclude that because the extended range of such devices would significantly increase the potential for interference and also make it more difficult to identify sources of interference, it would not be appropriate to allow higher power for unlicensed TV bands devices at this time. Indeed, such operation would be more appropriate under a licensed regime of regulation. The Commission therefore affirms its previous decision on fixed device power levels, but could revisit the issue of higher power levels for TV bands devices on a licensed or unlicensed basis at some point in the future as may be appropriate.

48. The Commission retained the current 100 mW maximum transmitter power limit for Mode I and Mode II personal/portable devices and decline to establish a new class of higher power vehicle mounted portable devices. As the Commission noted in the Second Report and Order, personal/portable devices generally pose a greater risk of harmful interference to authorized operations than fixed devices because these devices will change locations, making identification of both unused TV frequencies and the devices themselves, if interference occurs, more complex and difficult. The Commission also noted the significant distances at which interference could occur from a personal/portable device operating at greater than 100 mW would make it very difficult to identify a device that is the source of interference. The Commission therefore declines to increase the power limit for personal/portable devices at this time.

49. Additionally, the Commission is retaining the 50 mW power limit for sensingonly devices. The Commission stated in the Second Report and Order that the prototype TV bands devices it tested were able to sense the presence of signals from incumbent services under some conditions, but were unable to do so in others, such as in noisy environments or in the presence of strong adjacent channel signals. It further stated that th

FOR FURTHER INFORMATION CONTACT

Hugh Van Tuyl, Policy and Rules Division, Office of Engineering and Technology, (202) 4187506 or via email Hugh.VanTuyl@fcc.gov.