With the adoption of 802.11j will there be a difference on how it will be adapted in the US or will it follow the 802.11a standard in terms of power levels and antenna gains?
802.11j defines extensions allow 802.11a WLAN operation in the 4.9 to 5.0 GHz frequency band, complying with Japanese MPHPT regulations regarding operational mode, operational rate, radiated power, spurious emissions and channel sense. 802.11j defines uniform methods that let APs move to new frequencies or change channel width for better performance or capacity -- for example, to avoid interference with other wireless applications.
Currently, the 4.9 GHz band is only available for unlicensed use in Japan. It is reserved for use by public safety wireless applications in the US. However, FCC regulations regarding the 4.9 GHz band may be changing, making 802.11j of interest to 802.11a WLAN users in the US as well. To read the FCC's recent ruling, see this FCC Memorandum (FCC 04-265, PDF). For more speculation about 802.11j and its potential US impact, see these Wireless Watch and Wi-Fi Planet articles.
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