Cooperative Uplink VG-CDMA over Frequency Selective Generalized Gamma Slowly Fading Channels

Cooperative diversity has been recently proposed as a way of forming virtual Multi Input Multi Output (MIMO) channels that provide extraordinary gains in wireless fading environments. In this work, we develop, analyze and evaluate the uplink performance of a new cooperative scheme, Virtual Group CDMA (VG-CDMA) based on quasisynchronous communications and QPSK modulation. Users cooperatively synchronize themselves and establish quasisynchronous relaying links in a form of virtual group to share binary information symbols. Then, the QPSK modulation symbol constructed from itself and its cooperative user´s binary information symbol is sent to base station, which enables virtual MIMO system. The uplink performance of the proposed VG-CDMA over frequency selective generalized gamma slowly fading channels is obtained. Results show that VG-CDMA outperforms DS-CDMA.