Analysis of maximal-ratio transmit and combining spatial diversity

Abstract

Spatial diversity is still remaining as a powerful means to improve the transmission performance in a multipath fading environment. Various spatial diversity schemes have been proposed such as maximal-ratio transmit and combining (MRTC), selective MRTC, and space-time block coded transmit diversity (STBC-TD). In this paper, we derive a closed form expression for the received signal-to-noise ratio (SNR) achievable with MRTC for the case of base station (BS) having an arbitrary number of antennas and user-equipment (UE) having 2 antennas. Using the derived SNR expression, the average bit error rate (BER) performance of quaternary phase shift keying (QPSK) transmission in a Rayleigh fading environment is numerically evaluated. It is shown that MRTC provides the BER performance superior to STBC-TD and selective MRTC.