Performance Analysis of a Rate-Adaptive Dual-Branch Switched Diversity System

In this paper, a performance analysis of a dual- branch switched diversity system operating on identically distributed Nakagami-m fading channels is presented. An adaptive coded modulation (ACM) scheme is employed to increase the spectral efficiency of the system. The ACM scheme consists of a set of multidimensional trellis codes originally designed for additive white Gaussian noise channels, where the codes are based on quadrature amplitude modulation (QAM) signal constellations of varying size. The performance is evaluated by assuming perfect channel knowledge at the receiver and instantaneous feedback of channel state information, conveyed from the receiver to the transmitter on a zero-error feedback channel. Both spatially uncorrelated and correlated antenna branches are considered. The optimal switching threshold in terms of maximizing the average spectral efficiency is identified in the case of uncorrelated antenna branches.