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Planning and Implementing Wireless LANS
By Peter Rysavy Propagating into the Future
While we emphasize how to take advantage of wireless LANs today, it is worth noting some of the ongoing developments and what to expect over the next five years. This will give you a better idea of how wireless LANs might address your expanding needs, and whether you will be able to consider wireless LANs for other applications. There are a number of notable trends. One is that the performance of wireless LANs technology will keep increasing while costs will decrease. Another is that as wireless data usage grows, increasing amounts of spectrum will become available. Higher Performance At Lower Cost Early wireless LANs of the late 1980s offered throughputs of about 250 Kbps. The next generation reached 1 Mbps and today rates of 10 Mbps are available, albeit with lower coverage range. While 1 Mbps to 2 Mbps can be considered the standard today (with some higher-speed exceptions), 10 Mbps will become standard over the next couple of years, especially as new technologies such as pulse position spread spectrum are deployed. Also, expect to soon start seeing HiperLAN products offering about 24 Mbps. And standards work is already under way with HiperLAN and a wireless version of ATM to extend speeds to 155 Mbps, though affordable products at such higher data rates probably will not be available for another five years. Also, expect to see prices dropping, with 802.11 adapters falling as low as $200 in a couple of years. At these prices, wireless LANs could start competing with wired LANs for typical worker connectivity, and could start propelling wireless LANs into horizontal markets. Improvements in technology have allowed radio communications to take advantage of higher frequencies. Wireless LANs that originally operated at 900 MHz have migrated to the 2.4-GHz band. And now an increasing number of products are using the even higher 5.7-GHz ISM band. The possibility of cost-effective products at 5 GHz prompted the FCC in 1997 to allocate 300 MHz for a new band it is calling the Unlicensed National Information Infrastructure (UNII). As with the ISM bands, users can operate without a license, but to encourage innovation and free market forces the FCC is imposing virtually no restrictions on how this band is used except for transmission power levels. The UNII band, which spans from 5.15 to 5.35 GHz and 5.725 to 5.825 MHz, is more than twice all the spectrum allocated for PCS, which itself has spawned a massive expansion of the cellular telephone industry. The UNII band will provide a home for HiperLAN (which in Europe operates at similar frequencies) and for new wireless LAN technologies that will undoubtedly evolve to take advantage of this spectrum. Developments like UNII are representative of the overall trend. Microwave communications can now easily operate at frequencies as high as 40 GHz. Expect to see wireless LANs keep moving up in frequency and expect to see licensing bodies keep allocating additional spectrums at higher frequencies as market demand increases.
Updated January 14, 1998
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