AF and DF Protocols based on Alamouti ST Code

Abstract

In this work we propose a new amplify-and-forward (AF) protocol and a new decode-and-forward (DF) protocol based on the Alamouti space-time (ST) code, chosen because of its decoding simplicity. We also apply a new selection criterion for AF and DF protocols that improves their performance and solves the problem of bad performance at low SNR. Finally, we apply the Alamouti AF and DF protocols to a "non-line-of-sight" (NLOS) scheme to bring diversity. Outage probabilities and simulation results show that at low spectral efficiency, in spite of their rate of 1/2 symbol per channel use, these Alamouti AF and DF protocols have better performance than the non-orthogonal AF (NAF) protocol.