Performance of Single Carrier Transmission with Cooperative Diversity over Fast Fading Channels

Abstract

Space-time block coded (STBC) single carrier (SC) transmission was extended in a distributed fashion for practical implementation of user cooperation. However, STBC was designed under the assumption that the channel is static over the duration of a space-time codeword. Thus, the distributed STBC SC system suffers from the time selectivity of wireless fading channels. To achieve a reliable performance over fast fading channels, we propose a distributed space-frequency block coded (D-SFBC) SC transmission. This paper analytically compares the performance of these two distributed SC transmissions over fast fading environment. For evaluation of mean square error (MSE) over fast fading channels, we present a channel model that captures the time-varying nature of wireless channels. It gives an insight into the characteristics of inter-carrier interference and simplifies the evaluation of MSE. Using this model, it is proven that the D-SFBC SC transmission outperforms the D-STBC SC transmission when there exists a severe Doppler spread. Simulation results are also provided to validate our analysis and to compare two distributed single carrier transmission schemes.