Array processing for slow FHMA and hybrid FH/TDMA with overlap channel transmission

In this paper, we present an overlapped channel transmission (OCT) multiple access scheme which increases the uplink capacity of the slow FHMA or FH/TDMA communication systems. Traditional systems which use frequency division channels and guard bands waste useful spectrum. By using antenna array techniques, subscribers can communicate through frequency overlapped channels but still have satisfied performance. A practical system that uses 2-fold OCT to increase system capacities with the same total bandwidth is proposed along with an optimal beamforming algorithm. Simulation results show that the proposed blind beamforming algorithm almost achieves the Wiener solution and converges very fast within 40 iterations. We also discuss the beamforming performance when more than 2-fold overlapped channels are applied