Comparison of AF and DF relaying for uplink CDMA communications subject to constant multiple access interference cost

Abstract

In radio mobile cellular networks, the users located at the cell border suffer from a bad quality of service (QoS). Cooperative communication is a promising technique that can overcome this weakness by allowing these users to profit from powerful benefits of spatial diversity. Nevertheless, abstraction is usually made on the impact of the additional multiple access interference inherent to relaying. In a previous work, we have optimized amplify-and-forward (AF) relaying scheme subject to a constant multiple access interference cost for CDMA (Code Division Multiple Access) uplink communications. Here, we extend this work by dealing with performance optimization for decode-and-forward (DF) relaying subject to the same cost constraint for the same framework. We compare the performance of both optimized AF and DF schemes for different scenarii. A variety of simulation results reveals that DF relaying provides cellular performance enhancement in terms of BER (Bit Error Rate) over both direct transmission and AF relaying schemes.