Understanding HomeRF


About the same time WECA approved the 802.11 standard, several other types of wireless technologies were being introduced. Although a few have made a rather impressive niche in the Personal Area Network (PAN) market, the only other WLAN technology that came close to competing with 802.11 was HomeRF.

Using the Shared Wireless Access Protocol (SWAP), HomeRF merges the 802.11 FHSS standard with the six voice channels based on Digital Enhanced Cordless Telecommunications (DECT). In other words, the home network included both voice and data streams that could all work together at the same time. In addition, HomeRF devices do not require an access point to convert signals. The HomeRF devices do all the required conversion.

Understanding FHSS

HomeRF uses another frequency control standard called FHSS (Frequency Hopping Spread Spectrum) . Used in combination with a 2.4GHz frequency, a signal can change channels 50 times per second. This helps provide reliable service, even with the existence of other HomeRF networks. By using the entire frequency range, as illustrated in Figure 2.5, multiple networks can operate in the same area without fear of collision.

Figure 2.5. The Frequency Hopping Spread Spectrum.

graphics/02fig05.gif

Ironically, FHSS was also used in the preliminary implementations of the 802.11 standard. However, HomeRF used an enhanced version and managed to achieve a data rate of 1.6Mbps, as compared to the 1Mbps 802.11 reached.

This standard was short-lived because of the low bandwidth (1 “2Mbps) and the relatively short effective distance. One advantage that helped keep HomeRF in the market was its low cost. However, after the wireless fad caught on, 802.11b devices quickly dropped in price, and numerous vendors started producing equipment for WLANs.



Maximum Wireless Security
Maximum Wireless Security
ISBN: 0672324881
EAN: 2147483647
Year: 2002
Pages: 171

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