Radio frequency devices: Frequency hopping spread spectrum systems operating in 2.4 GHz band for wider operational bandwidths,

[Federal Register: July 20, 1999 (Volume 64, Number 138)]

[Proposed Rules]

[Page 38877-38878]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr20jy99-31]

FEDERAL COMMUNICATIONS COMMISSION

47 CFR Part 15

[ET Docket 99-231; FCC 99-149]

Spread Spectrum Devices

AGENCY: Federal Communications Commission.

ACTION: Proposed rule.

SUMMARY: This document proposes to revise the rules for frequency hopping systems operating in the 2.4 GHz band (2400-2483.5 MHz) to allow for wider operational bandwidths. We also propose to refine the method for measuring the processing gain of direct sequence systems. This action is taken to facilitate the continued development and deployment of spread spectrum technology, particularly for high data rate wireless applications.

DATES: Comments must be filedon or before October 4, 1999, and reply comments must be filedon or before November 2, 1999.

ADDRESSES: Address all comments concerning this proposed rule to the Commission's Secretary, Magalie Roman Salas, Office of the Secretary, Federal Communications Commission, 445 12th Street SW, Washington, DC 20554.

FOR FURTHER INFORMATION CONTACT: Neal McNeil, Office of Engineering and Technology, (202) 418-2408, TTY (202) 418-2989, e-mail: nmcneil@fcc.gov.

SUPPLEMENTARY INFORMATION: This is a summary of the Commission's Notice of Proposed Rule Making, ET Docket 99-231, FCC 99-149, adopted June 21, 1999, and released June 24, 1999. The full text of this document is available for inspection and copying during regular business hours in the FCC Reference Center, (Room TW-A306) 445 12th Street SW, Washington, DC. The complete text of this document also may be purchased from the Commission's duplication contractor, International Transcription Service, Inc., (202) 857-3800, 1231 20th Street, NW, Washington, DC 20036.

Summary of Notice of Proposed Rulemaking

1. Frequency Hopping Systems. Section 15.247 of the Commission's rules, permits frequency hopping spread spectrum systems to operate in the 2.4 GHz band with a maximum output power of 30 dBm (1 watt). The rules specify that frequency hopping systems operating in this spectrum must use a minimum of 75 hopping channels with each channel having a 20 dB bandwidth not exceeding 1 MHz. The average time of occupancy on any frequency must not be greater than 0.4 second within a 30 second period.

2. The Home RF Working Group (``HRFWG'') fileda request that the Commission interpret section 15.247 to allow frequency hopping systems in the 2.4 GHz band to operate with 3 MHz and 5 MHz bandwidths. HRFWG proposes to allow systems with bandwidths of up to 3 MHz to operate with output power no more than 25 dBm and channel occupancy time no greater than 0.05 second per hop. Each of the 75 channels will be used at least once during a 3.75 sec period. Like existing 1 MHz systems, the average time of occupancy on any channel will not be greater than 0.4 second within a 30 second period. HRFWG's proposal will allow systems using 5 MHz channels to operate with output power no more than 23 dBm and channel occupancy time no greater than 0.02 second per hop. Each of the 75 hopping channels will be used at least once during a 1.5 second period. Again, the average occupancy time on any channel will remain 0.4 second or less per 30 second period.

3. We do not believe these proposed rule changes will result in any significant increase in interference to direct sequence spread spectrum systems. We recognize that spectrum occupancy of frequency hopping systems in the 2.4 GHz band will increase as a result of the proposed changes. The existing rules require a minimum of 75 hopping channels each with a bandwidth of no more than 1 MHz. Given the 83.5 MHz of spectrum available in the 2.4 GHz band, no frequency is used more than once in the hop sequence. However, if the channel bandwidth is increased to 3 MHz or 5 MHz, overlapping channels will be needed to accommodate 75 hops. Accordingly, the average time of occupancy on any one frequency will increase. However, it appears that the proposed reduction in output power and time of occupancy would offset any potential increase in interference. Further, we observe that manufacturers of direct sequence systems that are concerned about interference can improve the robustness of their systems by increasing processing gain.

4. Direct Sequence Processing Gain. Under section 15.247(e) of the Commission's rules, direct sequence systems are required to exhibit a processing gain of at least 10 dB. The 10 dB minimum was established to ensure that a system is, in fact, spread spectrum in nature. Generally, systems employing a spreading rate of at least 10 chips/symbol meet the 10 dB processing gain requirement. The number of chips per symbol refers to the ratio of spreading imposed by the direct sequence high speed spreading code.

5. The Commission allows processing gain to be determined by either of two methods. The first is a direct measurement taken from the demodulated output of the receiver. The processing gain is calculated as the ratio, in dB, of the signal-to-noise ratio with the system spreading code turned off to the signal-to-noise ratio with the system spreading code turned on. Alternatively, in cases where the design of the system does not permit de-activation of the spreading code, an

   [[Page 38878]]

   indirect measurement of processing gain, based on receiver jamming margin (the ``CW jamming margin method''), is permitted. See 15 CFR 15.247(e)(2). The receiver jamming margin is representative of the ability of the receiver to reject other radio signals appearing on the same frequency. The test is generally viewed as an accurate measure of processing gain for systems employing spreading rates of at least 10 chips/symbol. However, in cases where the spreading rate is less, the results of the test are questionable.

6. The jamming margin test is based on use of a CW signal as an interference source. Some spread spectrum device manufacturers have suggested that the use of a Guassian noise interferer, instead of a CW interferer, would be more suitable for the jamming margin test. After reviewing the various submissions, we tentatively conclude that a Guassian interferer is likely to give a more accurate measure of processing gain because it is more closely related to the noise a system would encounter in a real-world environment. Therefore, we propose to permit the use of a Guassian interferer for determining receiver jamming margin.

7. The Commission has also received comments from manufacturers asserting that the current jamming margin test, along with a mathematical calculation of processing gain, should be required to demonstrate that systems using fewer than 10 chips per symbol are in compliance with the rules. The mathematical calculation would take into account the ``coding gain'' achieved by modulating and spreading of the baseband signal. We believe that this approach will provide greater assurance that the systems are in compliance. Accordingly, we propose to amend the rules to require manufacturers of direct sequence spread spectrum systems that use a spreading rate less than 10 chips per symbol to submit the results of the jamming margin test as well as a calculation of processing gain to verify compliance. Omnidirectional antenna operating at 250 mV/m.

   Initial Regulatory Flexibility Analysis

8. As required by Section 603 of the Regulatory Flexibility Act, 5 U.S.C. 603, the Commission has prepared an Initial Regulatory Flexibility Analysis (IRFA) of the expected significant economic impact on small entities by the policies and rules proposed in this Notice of Proposed Rule Making (``NPRM''). Written public comments are requested on the IRFA. Comments must be identified as responses to the IRFA and must be filedby the deadlines for comments on the NPRM. The Commission shall send a copy of this NPRM, including the IRFA, to the Chief Counsel for Advocacy of the Small Business Administration in accordance with paragraph 603(a) of the Regulatory Flexibility Act.

   1. Reason for Action

9. This rule making proceeding is initiated to obtain comment regarding proposed changes to the regulations for non-licensed transmitters.

   2. Legal Basis

10. The proposed action is taken pursuant to Sections 4(i), 301, 302, 303(e), 303(f), and 303(r) of the Communications Act of 1934, as amended, 47 U.S.C. 154(i), 301, 302, 303(e), 303(f), and 303(r).

    3. Description and Estimate of the Number of Small Entities to Which the Proposed Rules Will Apply

11. For the purposes of this NPRM, the RFA defines a ``small business'' to be the same as a ``small business concern'' under the Small Business Act, 15 U.S.C. 632, unless the Commission has developed one or more definitions that are appropriate to its activities. See 5 U.S.C. 601(3). Under the Small Business Act, a ``small business concern'' is one that: (1) is independently owned and operated; (2) is not dominant in its field of operation; and (3) meets any additional criteria established by the Small Business Administration (SBA). See 15 U.S.C. 632. SBA has defined a small business for Standard Industrial Classification (SIC) category 4812 (Radiotelephone Communications) to be small entities when they have fewer than 1500 employees. See 13 CFR 121.201. Given this definition, nearly all such companies are considered small.

    4. Description of Projected Reporting, Recordkeeping and Other Compliance Requirements

12. Part 15 transmitters are already required to be authorized under the Commission's certification procedure as a prerequisite to marketing and importation. See 47 CFR 15.101, 15.201, 15.305, and 15.405. The changes proposed in this proceeding would not change any of the current reporting or recordkeeping requirements. Further, the proposed regulations adds permissible measurement techniques and methods of operation. The proposals would not require the modification of any existing products.

    5. Significant Alternatives to Proposed Rules Which Minimize Significant Economic Impact on Small Entities and Accomplish Stated Objectives

13. None.

    6. Federal Rules That May Duplicate, Overlap, or Conflict With the Proposed Rule

14. None.

    List of Subjects in 47 CFR Part 15

    Communications equipment.

    Federal Communications Commission. Magalie Roman Salas, Secretary.

    [FR Doc. 99-18428Filed7-19-99; 8:45 am]

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