The National Telecommunications and Information Administration (NTIA) commends the Federal Communications Commission (Commission) for initiating this proceeding to expand the options for unlicensed device use, and particularly, linking such expanded use to adoption of new technologies for active interference-avoidance. NTIA agrees with the Commission regarding the significant benefits to the economy, businesses, consumers, and government agencies that could be gained by allowing unlicensed devices to operate in the 5.47-5.725 GHz frequency range, provided that such operation is tied to effective implementation of active interference-avoidance techniques. NTIA would also like to commend the Commission for its careful consideration and review of existing Part 15 Rules in the 5.25-5.35 GHz band as well as consideration of the federal government and private sector spectrum requirements in the 5 GHz frequency range. NTIA provides the following comments to specific issues raised in the Unlicensed-National Information Infrastructure (U-NII) Notice of Proposed Rulemaking (NPRM) that may have an impact on critical federal systems used for scientific research, aviation, and national defense.
NTIA supports the Commission’s proposals to upgrade the frequency allocations of federal government Radiolocation Service, and federal and non-federal government Space Research Service (active) and the Earth Exploration-Satellite Service (active) in the 5 GHz frequency range. Upgrading these allocations is consistent with the allocations adopted internationally, and will provide the necessary protection to federal systems supporting national defense as well as federal and non-federal commercial and scientific operations. In addition to the allocation upgrades in the 5 GHz frequency range, several footnotes were adopted at the World Radiocommunication Conference 2003 (WRC-2003). There were also modifications made to several existing footnotes in the 5 GHz frequency range. The Commission’s proposal to modify the U.S. Table of Frequency Allocations did not include the new footnotes or the modifications to existing footnotes that were adopted at WRC-2003. NTIA believes that the modifications to the U.S. Table of Frequency Allocations should include the appropriate new footnotes and modifications to existing footnotes adopted at WRC-2003. NTIA believes that the inclusion of these new footnotes and the modifications to existing footnotes are necessary because of the complex sharing arrangements that exist between the diverse federal and non-federal government radio services operating in the 5 GHz frequency range.
NTIA supports the Commission’s proposal to modify the Part 15 Rules to allow U-NII devices to operate in the 5.47-5.725 GHz band on a non-interference basis. Utilization of the mitigation measures proposed in the NPRM along with the additional 255 MHz of spectrum for U-NII devices to spread across will provide protection to vital government systems. The Commission’s proposal will also meet current industry needs as well as future growth in the radio local area network radio local area network (RLAN) industry which has proven to be one of the few technology success stories in the current economy.
NTIA concurs with the Commission’s proposal that Dynamic Frequency Selection (DFS) should be required in the existing 5.25-5.35 GHz U-NII band as well as the proposed U-NII 5.47-5.725 GHz band. NTIA also concurs with the technical limits on DFS proposed by the Commission. Comprehensive studies carried out jointly between NTIA, Department of Defense, and private industry with Commission representatives has proven the requirement for these technical limits. Specifically, NTIA considers the proposed power limits, detection threshold, move time, and non-occupancy period as fundamental for the protection of government radars and no relaxation in the proposed values can be accepted based on the studies cited above. DFS is an integral part of the protection measures that allows for sharing between the U-NII devices and existing primary government users. NTIA is of the opinion that the DFS mechanism should be required to detect a single radar pulse present during coincidence of the transmitted radar pulse and the dedicated listen period of the DFS mechanism between each packet/frame. The requirement should be for detection of a single pulse during this coincidence period. In addition, the DFS mechanism should be allowed to average received power over successive 1 microsecond periods during the dedicated listen period. Given the typical pulse widths and pulse repetition rates of the radars operating in these bands, as well as the average power levels transmitted by these radars, the DFS mechanism should have no problems detecting single radar pulses during coincidence. This will not allow for radar signal detection and instead forces the DFS to rely on signal detection above the DFS detection threshold no matter the source. This provides further protection of radar systems given the high probability of masking of radar signals from adjacent, competing U-NII devices.
NTIA’s Office of Spectrum Management is leading a government/industry project team to develop proposed compliance measurement procedures for DFS equipped U-NII devices. This project team will be responsible for addressing technical issues related to the generation of radar signals and the techniques to reliably measure these signals. NTIA believes that this government/industry project team has the expertise to provide guidance to the Commission in the development of the compliance measurement procedures for DFS equipped U-NII devices. A first draft of the proposed compliance measurement procedures is provided as part of these comments. There are plans in the November 2003 timeframe for manufacturers to bring DFS equipped devices to NTIA’s Institute for Telecommunication Sciences to validate the draft measurement procedures. This testing will be dependent on the availability of DFS equipped U-NII devices. NTIA will submit a report to the Commission documenting the results of these measurements and any modifications to the draft procedures. NTIA believes that providing the draft measurement procedures to the Commission as part of the public record will allow other parties that are not participating in the government/industry project team to review and provide comments on the proposed measurement procedures.
The current Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards require Transmitter Power Control (TPC) in both the 5.25-5.35 GHz and 5.47-5.725 GHz bands as a means to facilitate sharing among U-NII devices. Therefore, NTIA believes that it should not create a burden on industry to implement TPC in both bands. NTIA believes that TPC will provide a mitigation factor of at least 3 dB within the EESS/SRS satellite footprint providing additional protection for these critical government operations.
NTIA agrees with the Commission’s transition schedule for domestically manufactured U-NII devices operating in the 5.25-5.35 GHz band. NTIA believes that this approach will lessen the burden on manufacturers by allowing them adequate time to redesign their devices to comply with the DFS and TPC requirements necessary to protect federal systems. NTIA recommends that the Commission require that imported U-NII devices operating in the 5.25-5.35 GHz band adhere to the Commission’s Rules (e.g., DFS and TPC), one year after the date of publication of the Report and Order in the Federal Register.
Finally, NTIA recommends that the Commission include additional definitions in their rules for U-NII devices. The additional definitions proposed by NTIA are consistent with the terminology employed by the RLAN industry, and will help to avoid confusion that may arise when developing compliance measurement procedures for U-NII devices.