Effects of Mutual Coupling on the Diversity Order of EGT Systems

Multiple-input multiple-output (MIMO) wireless systems have gained attention due to their ability to provide substantial gains in capacity and quality. This paper proposes equal gain transmission (EGT) to provide diversity advantage in MIMO systems experiencing Rayleigh fading and correlation. The applications of EGT with selection diversity combining (SDC), equal gain combining (EGC), and maximum ratio combining (MRC) are addressed. Since in practice full channel knowledge at the transmitter is difficult to realize, a quantized version of EGT is proposed. Because small distances between the antennas on a mobile unit causes mutual coupling, in this paper, first a new approach to calculate the effects of coupling is introduced; and then the diversity-order for systems that use EGT and any different combining schemes with various distances between the antennas on a mobile unit, with coupling calculated by the conventional method and the new method, and without considering the effect of coupling are compared by simulation.