Importance

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Abstract

A frequency hopping spread spectrum wireless data communications network is disclosed. Time mark frames are transmitted by each base station at a regular cadence and each time mark frame contains all information necessary to determine the hopping sequence of channels, a sub-set of possible channels in use, and the particular channel upon which the time mark was transmitted. Receipt of the time mark resynchronizes a slot clock that is used by the wireless terminals in implementing a media access protocol with defined synchronous time slots. The base station to roaming terminal radio link is half duplex. Each base station broadcasts an end-of-message frame during a hop period that indicates that it has no more data to send during that hop. If there are no inbound messages a roaming terminal needs to send, it puts its receiver in a low power mode until the next hop time approaches. Look ahead acquisition of the hopping sequence for a nearby base station when the received signal level for the current base station drops is also disclosed.

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First Claim