5.8 GHz Band Said to Interfere with Missile Systems’ Radar

Rules unveiled last month allow unlicensed applications such as wireless loops (WID July 15 p4). But, Geiss said, given power limits on the 5150-5350 MHz and 43570-5725 MHz bands, “the range that can be achieved is not the best, although mesh networks may contribute to the range that can be achieved.”

Citing a “significant level of interest” among industry, users and public bodies in deployment of high- speed communications with fixed, nomadic and/or mobile usage nodes, the EC Radio Spectrum Committee RSC) published a working document on BWA in May. It said successful commercial development of such systems would offer an alternative for access to high-speed voice and data services in home and office, and in-between. Central to the success of BWA offerings is availability of harmonized frequencies for the systems to operate in -- plus removal of unnecessary restrictions on those frequencies, the RSC said.

The document focussed on 3 frequencies, including the 5.7-5.9 GHz band. The RSC noted the possible incompatibility of wireless access systems/radio local area networks with some military aeronautical radar, saying introduction of new technologies using that band would “require further attention.” Another group, the newly constituted Electronic Communications Committee Joint Project Team on Broadband Fixed Wireless Applications, is studying the compatibility of fixed wireless and other systems in that band.

In the U.K., the 5.8 GHz band opened for fixed wireless applications in Feb. 2004. The Office of Communications (Ofcom) imposed a “light licensed” regime on what’s known in the U.K. as “Band C,” requiring electronic registration by new services of all transmitting terminals at a Pounds 1 ($1.75) fee per terminal installed yearly. All fixed wireless access services in the band are licensed on a nonprotected and noninterference basis.

Use of the band is subject to 2 technical parameters, said John Wilson, co-founder of Open Spectrum U.K.: (1) Dynamic frequency selection, where the system adapts to avoid interference. (2) Transmit power control, which lets wireless local area network users use the minimum output power necessary to transmit data signals if interference is encountered. These conditions were set by Ofcom ancestor the Radiocommunications Agency, ostensibly to avoid interference with U.K. military missile radar. But, Wilson said, the missiles involved actually were American weapons using the 5.8 GHz frequency, and the RA also claimed the use of the band interfered with some broadcast uses, delaying even longer its approval for wireless applications.

Moreover, while regulators have subjected Band C to regulation, the terms of reference for a wireless access group created by the RA during a public consultation were actually to look at license-exempt access, Wilson said. By contrast, the FCC established a principle for unlicensed use of 5.8 GHz, called Band B in the U.S.

Use of Band C to bridge the last mile sparked new turns, such as growth of community networks and new market entrants providing wireless access to broadband, Wilson said. Wireless ISPs emerged in rural areas where other technologies weren’t available, until telcos fought back by pushing ADSL. At one point, he said, the last mile problem in the U.K. became “inverted,” with some at the end of a telco’s network considering themselves as being at the start of their own community networks: “Wireless as a first-mile technology.”

Debate over use of the 5.8 GHz band for BWA will go on at the group’s Oct. 5 meeting, Geiss said. The EC is “quite interested in the potential of wireless loops to cover the last mile,” said Philippe Lefebvre, principal administrator of the EC Radio Spectrum Policy Unit. In fact, he said, the commission is considering an overarching approach to regulating all wireless access platforms for electronic communications services.