Hopfield neurobeamformer for spread spectrum communications

In cellular or mobile systems, provisions must be made for a high-quality reception. Therefore, adaptive beamforming can be combined with spread spectrum modulation in order to provide interference protection for users within a cell or users in co-cells. Hopfield (1984) neural network is used to carry out adaptive beamforming with direct sequence spread spectrum signals. A reference signal generator is employed to derive the desired signal for the adaptive processor. A PN code is used to spread the data signal which is biphase modulated. At the receiver end, this code is used to extract the desired signal component from the array output and reject any narrowband interference signals. Simulations are carried out for 8-element linear and circular arrays. The performance of the neurobeamformer is evaluated in the presence of interference from directions very close to the desired signal. Simulations also include a scenario where a multipath signal impinges on the array