Exact and asymptotic BEP of cooperative DS-CDMA systems using decode and forward relaying in the presence of multipath propagation

In this paper, we derive the bit error probability (BEP) of cooperative DS-CDMA systems using decode and forward (DF) relaying. We consider a conventional DF protocol where all the relays that have correctly decoded transmit and a selective DF (S-DF) protocol where we activate only the relay that offers the best instantaneous signal to noise ratio (SNR) of the relay to destination link among the relays that have correctly decoded. The derived results are valid for any multipath intensity profile of the channel, any path delays and take into account the correlation of the multipath gains.