Conformity Magazine - September 2007 - (Page 31)

Author’s Note: The intent of this article is to share some practical advice on how to achieve compliance with the FCC’s new dynamic frequency selection (DFS) requirements. However, in order to provide some general background information on this subject, the article begins with an excerpt from the article “Dynamic Frequency Selection and the 5 GHz Band,” written by our colleague Mark Briggs and originally published in Conformity in December 2005. he advent of the 802.11a wireless market and the constant push to open up new spectrum for unlicensed use created a requirement for dynamic frequency selection (DFS), a mechanism to allow unlicensed devices to share spectrum with existing radar systems. The regulatory requirements for DFS, along with requirements for transmit power control (TPC) and uniform channel loading have been adopted in the United States, Europe and Japan and are being considered by many other regulatory domains looking at adopting the 5GHz bands for unlicensed (and possibly licensed) devices. Some Background on DFS Requirements in the United States The Federal Communications Commission (FCC) had already opened up the 5150 – 5350 MHz band when it adopted the UNII rules into Part 15. The FCC opened up the 5470 – 5725 MHz band by working with industry and the Department of Defense through the U.S. Department of Commerce, National Telecommunications and Information Administration (NTIA), and released its Report and Order FCC 03-287 [3]. To release the 5470 – 5725 MHz, a requirement for DFS was proposed to cover the new band and the existing 5250 – 5350 MHz band. The timing and threshold requirements were identical to those of EN 301 893 v1.2.3, but the signal parameters were different and included a frequency hopping radar. The original time line for these bands would have required any devices using the 5250 – 5350 MHz band that would be certified after January 2005 to have DFS capability. Issues with the implementation of a test procedure (such as detection success rates) and the radar parameters caused the postponement of this date first to January 2006 and ultimately to July 2006. The main concern from the government’s side was that the detection algorithms implemented might only look for signals with the specific parameters listed, and industry was concerned that detection rates might not be achievable in the proposed, high-traffic (50% channel utilization) environment. The big challenge for the FCC-related test methods was to develop methods for evaluating the frequency hopping radar (preferably avoiding test labs having to invest in expensive frequency agile signal generators) and the ability to generate the bin 5, long duration waveform that includes chirped pulses of varying lengths. Trials by NTIA have demonstrated that devices are capable of detecting the various waveforms, and have also validated some alternate test procedures for simulating frequency hopping waveforms. Additional trials with real radars were the next step, and these results and further discussions between industry and government finalized the formal test procedures and pass/fail criteria. Once these issues were resolved, any products that required certification of DFS capability had to be certified by the FCC. At the same time, the FCC also performed surveillance audits on many devices until DFS capabilities had been proven. As the 5GHz bands are opened up in other geographic areas, it can be expected that DFS requirements will be included in each country’s spectrum allocation. Now that the U.S. has ironed out the prevailing issues with its DFS requirements, it is hoped that the concordance reached between the various industry and governmental parties will assist in making regulations that match the requirements of existing spectrum users and new wireless technologies in other markets. Practical Advice for Meeting the FCC’s DFS Requirements On June 30, 2006 when the FCC issued its Report & Order mandating official DFS certification requirements for devices operating in the 5 GHz band, wireless device manufacturers faced a new set of compliance challenges that they did not have to contend with in the past. Since those requirements went into effect, we have assisted numerous companies in achieving their DFS certification requirements and have KTL advert.ai 14/2/07 learned some very valuable lessons 11:50:14 way. With the along the Giving you the confidence to connect KTL is an accredited testing laboratory specializing in telecoms, IT, electrical and electronic products. KTL offers testing services for DSL, Safety, Environmental, EMC, Wireless and Telecoms to internationally recognized test standards. C M In addition to the test services KTL also provides compliance management services to assist clients with access to international markets. Our expertise in fixed wire telecommunication technologies makes us a world leader in the testing and evaluation of broadband technologies. KTL is recognized by the DSL Forum as an ITL (independent test laboratory) for DSL interoperability testing. Y CM MY CY CMY K 4701 Patrick Henry Drive, Building 19, Santa Clara CA 95054, USA. 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Table of Contents Feed for the Digital Edition of Conformity Magazine - September 2007

Contents Editor’s Note FCC Extends Disability Access Requirements to VOIP Commission Fines Importer $3 Million Over Non-Compliant TVs FCC Gets Tough on Retailers Over Analog TV Tuner Labeling Analog Cellular Service Sunset Date Reaffirmed Commission Adopts Recommendations of Katrina Panel Free-Space Antenna Factors Through the Use of Time-Domain Signal Processing Editorial Correction ESD Open Forum An Update on Revisions to IEC 61000-4-2, the Basic Standard on ESD Practical Advice for Meeting the DFS Testing Requirements of the FCC The EMC Impact of Embedded Software ESD Design Buyer's Guide Tate Renominated to the FCC EPA Releases Report on U.S. Electronic Waste Additional Standards For The EU’s Toy Directive Medical Device Manufacturer Enters Consent Order Updated Guidance Document on Laser Products Issued FDA Offers Advice on Defective Heating Pads CPSC Issues China Product Safety Program Report Other CPSC Actions In The News IEC Standards Update Product Reviews Product News UL Standards Update From Our “You Can’t Make This Stuff Up” Department Looking Back: Items from Past Issues of Conformity Advertisers

Conformity Magazine - September 2007

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