| 摘要 |
A wireless communications system is described for subscribers scattered at distances of up to 40 km. Wireless access for subscribers is provided from wireless base-stations (WBS) that are connected to a PSTN access node 16 via T1 links. These links support the subscriber traffic, and also provide network management. Where, due to terrain, the whole area can not be served from a single WBS site, additional WBS may have to be installed to provide fill-in coverage. However, all WBS in the coverage area are connected to the same PSTN access node. A wireless loop air interface structure consists of 2304 bits per 4 milliseconds divided into an outbound portion and an inbound portion with a gap of 48 bits between. The communications air interface uses a Frequency Hopping Spread-Spectrum (FHSS) air interface as specified for the 2.4-2.4835 GHz ISM band. The FCC regulations for occupied channel avoidance FH are given in 47CFR2.47(h). The intelligent adaptation of the FH code used by each WBSR follows this regulation. This is done by making each WBSR individually select and/or adapt its hop set, based on its detection of potentially interfering signals.
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