Cooperative diversity schemes for uplink single-carrier FDMA systems

Single-carrier frequency division multiple access (SC-FDMA) is considered as a promising technique that is adopted in the uplink for the upcoming 3GPP long term evolution (LTE). This is because it keeps most of the advantages of OFDMA in addition to low peak to average power ratio (PAPR). Designing diversity achieving schemes for SC-FDMA is a challenging task. The code should not affect the PAPR among other constraints. In this paper, we propose cooperative diversity schemes for SC-FDMA systems. Specifically, distributed space–time/frequency codes are proposed. The proposed distributed space–frequency code (DSFC) takes into account the low PAPR which is the feature of the system. Both decode-and-forward (DAF) and amplify-and-forward (AAF) protocols are considered. Erroneous decoding at the relay node is taken into account. Moreover, we propose a bandwidth efficient distributed space–time code (DSTC) for slow fading relay channels with DAF. Analytical and simulation results indicate that the proposed schemes achieve full diversity at the expense of small performance loss compared to the proposed codes in the literature.