Cooperative diversity for synchronous uplink DS-CDMA transmission over Rayleigh frequency flat fading channel

This paper presents an analysis of cooperative direct-sequence code division multiple access (DS-CDMA) relay communications with one source terminal and two relay nodes with multiuser detection over the frequency-flat fading channel for uplink transmission where the decode-and-forward (DF) protocol is employed at the relay nodes. We analyze for synchronous transmission with binary phase shift keying (BPSK) modulation. Bit error rate (BER) performance expressions are derived. In the analysis, we assume that the relay nodes correctly decode information and at BER 10−2 improvement is acquired at Eb/N0 = 16 dB. The effect various processing gain (N) is simulated. Numerical results show that the BER can be improved by increasing the processing gain and BER expressions are obtained by assuming that the relay nodes forwards information only if they correctly decode information and we assume that perfect cyclic redundancy check (CRC) is applied at the relays.