Spread Spectrum Devices

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

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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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