Increasing the capacity of GSM cellular radio using adaptive antennas

The capacity of mobile cellular radio networks can be considerably increased if a higher level of cochannel interference can be tolerated. An adaptive antenna combines the outputs of an array of elements to maximise the wanted signal and suppress interfering signals. The author proposes an adaptive antenna algorithm suitable for GSM and the urban multipath environment. The algorithm is based on iterative reference signal reconstruction from the GSM training sequence. The average error rate is obtained by simulation for four equal power interfering signals and an urban GSM multipath model. An adaptive antenna can only practically be deployed at the base station. Realising its gains in a real network on both the up and downlinks requires, for the downlink, a number of techniques. This is discussed and a concept of how the full capacity gains can be achieved in an evolutionary manner on both links is proposed. The concept is equally applicable to the DCS 1800 and DCS 1900 systems based on GSM