[Federal Register Volume 64, Number 138 (Tuesday, July 20, 1999)]
[Proposed Rules]
[Pages 38877-38878]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-18428]
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FEDERAL COMMUNICATIONS COMMISSION
47 CFR Part 15
[ET Docket 99-231; FCC 99-149]
Spread Spectrum Devices
AGENCY: Federal Communications Commission.
ACTION: Proposed rule.
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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 filed on or before October 4, 1999, and reply
comments must be filed on 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:
[email protected].
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'') filed a 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 filed by 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.
A. Reason for Action
9. This rule making proceeding is initiated to obtain comment
regarding proposed changes to the regulations for non-licensed
transmitters.
B. 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).
C. 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.
D. 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.
E. Significant Alternatives to Proposed Rules Which Minimize
Significant Economic Impact on Small Entities and Accomplish Stated
Objectives
13. None.
F. 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. 99-18428 Filed 7-19-99; 8:45 am]
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