Abstract
This paper presents a simple and robust hybrid combiner for the multiuser massive multiple-input multiple-output (MIMO) uplink. The hybrid beamforming is used in massive MIMO systems to reduce the number of radio frequency chains. Radio frequency chain consists of power hungry electronic components like mixer, analog-to-digital converter / digital-to-analog converter etc. This paper proposes a Householder based hybrid beamforming (HHBF) design to simultaneously reduce the beam domain inter-user interference and increase the sum-rate performance of massive MIMO uplink. The Householder reflectors generate the orthogonal analog combiner matrix which not only reduces inter-user interference but also helps reduce the dimension of the digital combiner. It has been shown that the proposed HHBF scheme provides better sum-rate performance than the Gram-Schmidt based hybrid beamforming design in the real-World ill-conditioned MIMO channel. Simulation results show that the beam domain orthogonality error remains less than 0.5 with 0.97 probability and the proposed HHBF provides 25.95% increased sum-rate at 10 dB SNR.