Cooperative communications aided downlink DS-CDMA with transmitter preprocessing: Performance results

Abstract

In this article, we analyze the performance of a downlink (DL) direct sequence code division multiple access (DS-CDMA) system aided by cooperative diversity for the bad urban power-delay distribution pertaining to ITV-R. The considered DL system supports multiuser transmitter preprocessing (MUTP) to mitigate the DL multiuser interference (MUI) at the relay stations (RSs) and mobile stations (MSs). TP employed at the base station (BS) is based on formulating a subspace that is orthogonal to the interfering subspace with the aid of singular value decomposition (SVD). The relays in our considered work support decode and forward (DF) protocol. At the mobile stations (MSs) the user specific signals are combined with the aid of classical maximal ratio combining (MRC) principle. Our simulation study shows that the relay aided DL DS-CDMA system with MVTP achieves better performance in terms of bit error rate (BER) as the DL MUI at the relays is completely eliminated by the preprocessing matrix employed at the BS.