Adaptive antenna system for diversity and interference avoidance in a multi-station network

Abstract

The invention provides a method of operating a communication network and a network itself. The network comprises a plurality of wireless stations, each station being able to transmit and receive data so that the network can transmit a message comprising a plurality of data packets from an originating station to a destination station via at least one intermediate station. At least some of the stations have a controllable antenna system operable to direct a null selectively. The method includes selecting, at each station, one or more probing channels for the transmission of probe signals to other stations. At stations having a controllable antenna system, the presence of interference on said one or more probing channels is detected, and one or more nulls are selectively directed towards the source or sources of the interference. Typically, a null is directed towards a source of interference where the level of the interference exceeds a predetermined level. Each station transmits neighbor gathering probe signals on the selected probing channel or channels, and other stations which receive the neighbor gathering probe signals from a probing station respond directly or indirectly to thereby indicate to the probing station their availability as destination or intermediate neighbor stations. The presence of the nulls affects the ability of other stations to receive the neighbor gathering probe signals, and the resulting variations in the connectivity between stations provides variations in the availability of neighbor stations to each station.