PUBLIC NOTICE Federal Communications Commission 445 12th St., S.W. Washington, D.C. 20554 News Media Information 202 / 418-0500 Internet: http://www.fcc.gov TTY: 1-888-835-5322 DA 09-1427 Released: June 25, 2009 WIRELESS TELECOMMUNICATIONS BUREAU SEEKS COMMENT ON REQUEST OF ALCATEL-LUCENT, et al. FOR INTERPRETATION OF 47 C.F.R. § 101.141(a)(3) TO PERMIT THE USE OF ADAPTIVE MODULATION SYSTEMS WT Docket No. 09-106 Comments Due: July 27, 2009 Reply Comments Due: August 11, 2009 On May 8, 2009, Alcatel-Lucent; Dragonwave Inc.; Ericsson Inc; Exalt Communications; Fixed Wireless Communications Coalition; Harris Stratex Networks; and Motorola, Inc. (“Petitioners”) filed a request for a declaratory ruling pursuant to Section 1.2 of the Commission’s Rules.1 In their Request, Petitioners ask the Wireless Telecommunications Bureau (“Bureau”) to interpret Section 101.141(a)(3) of the Commission’s Rules2 to permit data rates to drop for brief periods below the minimum payload capacity specified in the rule, when a link would otherwise be temporarily out of service, so long as the values mandated by the rule are maintained both in normal operation and on average.3 Section 101.141(a)(3) of the Commission’s Rules sets forth capacity and loading requirements which must be met by equipment operating in the 4, 6, 10, and 11 GHz bands for point-to-point systems operating under Part 101 of the Commission’s Rules.4 These capacity and loading requirements are designed to promote efficient use of the spectrum.5 Section 101.147 of the Commission’s Rules specifies authorized channel bandwidths in each band.6 For each authorized bandwidth, Section 101.141(a)(3) of the Commission’s Rules specifies a minimum payload capacity, expressed in megabits per second.7 According to Petitioners, the industry has generally construed the minimum payload requirements as applying each and every second the link is in service.8 Petitioners assert that fixed service links, 1 47 C.F.R. § 1.2. Request for Interpretation of Section 101.141(a)(3) of the Commission’s Rules to Permit the Use of Adaptive Modulation Systems (filed May 8, 2009) (“Request”). 2 47 U.S.C. § 101.141(a)(3). 3 Request at 2, 5. 4 47 C.F.R. § 101.141(a)(3). 5 See Reorganization and Revision of Parts 1, 2, 21, and 94 of the Rules to Establish a New Part 101 Governing Terrestrial Microwave Fixed Radio Services, et al., WT Docket No. 94-148, CC Docket No. 93-2, RM-7861, Report and Order, 11 FCC Rcd 13449, 13476 ¶¶ 76-77 (1996). 6 47 C.F.R. § 101.147. 7 47 C.F.R. § 101.141(a)(3). 8 Request at 2. 2 especially long links, are subject to atmospheric fading: a temporary drop in received power caused by changes in propagation conditions.9 Fading leads to an increase in bit errors, and sometimes to a complete loss of communications.10 According to Petitioners, one way to combat fading is by briefly reducing the data rate, which requires a temporary change in the type of modulation, a process called “adaptive modulation.”11 Petitioners acknowledge that the use of adaptive modulation may reduce the minimum payload capacity below the value specified in the rule for a short time, although this still represents an increase over the otherwise zero level during the fade.12 Petitioners further allege that, in a properly designed system, fading conditions that might trigger adaptive modulation occur well under one percent of the time, and thus, even under pessimistic assumptions, a system employing adaptive modulation will comfortably achieve the minimum on average.13 Petitioners ask that the Bureau confirm that the use of adaptive modulation is consistent with Section 101.141(a)(3) of the Commission’s Rules.14 Specifically, Petitioners ask the Bureau to rule that it is permissible for data rates to drop for brief periods below the minimum payload capacity specified in the rule, when a link would otherwise be temporarily out of service, so long as the values mandated by the rule are maintained both in normal operation and on average.15 They assert that the proposed reading of the rule fully maintains the rule’s purpose by enhancing spectrum efficiency.16 Petitioners also state that the interpretation would allow for the continued handling of critical traffic when the link would otherwise be inoperative.17 They claim that the use of adaptive modulation could preserve network synchronization during fading, which could eliminate several additional minutes of outage.18 Petitioners acknowledge that a license application and prior coordination for a system that uses adaptive modulation must list all of the modulations that the system might use, with their respective emissions designators.19 We seek comment on Petitioners’ Request. Interested parties may file comments on or before July 27, 2009, and reply comments on or before August 11, 2009. All filings must be addressed to the Commission’s Secretary, Marlene H. Dortch, Office of the Secretary, Federal Communications Commission, 445 12th Street, SW, Suite TW-A325, Washington, DC 20554. Comments may be filed under WT Docket No. 09-106 using the Commission’s Electronic Comment Filing System (ECFS) or by filing paper copies.20 Parties that choose to file by paper must file an original and four copies of each filing. Commenters must also send a copy to Best Copy and Printing, Inc., 445 12th St, SW, Suite CY- 9 Id. at 3. 10 Id. 11 Id. 12 Id. 13 Id. 14 Id. 15 Id. at 2, 5. 16 Id. at 4. 17 Id. 18 Id. 19 Id. 20 Instructions for filing paper copies can be found at http://www.fcc.gov/osec/guidelines.html or by calling the Office of the Secretary at 202-418-0300. For help filing electronically, see Electronic Filing of Documents in Rulemaking Proceedings, 63 FR 24121 (1998) and http://www.fcc.gov/cgb/ecfs. 3 B402, Washington, DC 20554, by telephone at 800-378-3160 or 202-488-5300, fax at 202-488-5563, or e-mail at fcc@bcpiweb.com. Petitioners’ Request and comments filed in response to this Public Notice will be available via the ECFS, in the Commission's Reference Center,21 or from Best Copy and Printing, Inc. This matter shall be treated as a “permit-but-disclose” proceeding in accordance with the Commission’s ex parte rules.22 FOR FURTHER INFORMATION, CONTACT: Barrett Brick of the Wireless Telecommunications Bureau, Broadband Division, at (202) 418-1065, Barrett.Brick@fcc.gov. Action by the Chief, Broadband Division, Wireless Telecommunications Bureau. -FCC- 21 The Commission’s Public Reference Center is located at Portals II, 445 12th Street SW, Room CY-A257, Washington, DC 20554. 22 See 47 C.F.R. §§ 1.1200, 1.1206. Ex parte presentations that are made with respect to the issues involved in the Petition will be allowed but must be disclosed in accordance with the requirements of 47 C.F.R. § 1.1206(b).