Maximal-ratio-combining array beamforming assisted by training sequences for SDMA mobile radios

This paper proposes and discusses the study of a non-blind type digital beamformer that can be applied to receiving array antennas with many elements. It can steer different beams independently to different users at the same frequency and of the same modulation type located in different unknown directions. The proposed beamformer is comprised of the combination of a spatial discrete Fourier transform (DFT) and maximal ratio combining (MRC) to training sequences in the complex baseband. Numerical simulations show that this beamformer can provide fast acquisition, sufficient beam isolation, and stable tracking without extensive computations such as those that would be needed for heavy matrix operations or nonlinear optimization.