Cooperative uplink VG-CDMA over frequency selective generalized ? slowly fading channels

Abstract

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.