Performance of relay assisted multiuser uplink MIMO wireless communication using Walsh Hadamard sequences

This paper compares the performance of single user and multiuser with Walsh Hadamard spreading sequences for relay assisted wireless link as well as direct link. Space Time Block Coding (STBC) is used for encoding the information at user's handset and relay. Input information are mapped using Walsh Hadamard spreading sequences and send to a QPSK or 16 QAM or 64 QAM modulator. Modulated symbols are encoded by STBC encoder and split into n streams which are simultaneously transmitted using n transmit antennas. Relay receives the Rayleigh fading effected signals where it decodes and forwards the signals for destination after further encoding using STBC. It is observed that there is around 9-12 dB coding gain for using Walsh Hadamard spreading sequences in multiuser system and there is around 11 dB coding gain for using relay in the MIMO system.