Quadrature sub-branch hybrid selection/maximal-ratio combining

A quadrature sub-branch hybrid selection/maximal-ratio combining (QBHS/MRC) scheme for one-dimensional modulations in Rayleigh fading is proposed. At the receiver, N diversity branches are split into 2N in-phase and quadrature sub-branches. Traditional hybrid selection/maximal-ratio combining (H-S/MRC) is then applied over the 2N sub-branches. The symbol error rate (SER) of M-ary pulse amplitude modulation (PAM), including coherent binary phase shift keying (BPSK), with QBHS/MRC is derived. The mean output signal-to-noise ratio (SNR) of a QBHS/MRC combiner is given. The performances of QBHS/MRC and H-S/MRC are compared. Results show that QBHS/MRC systems outperform traditional H-S/MRC systems.