Channel Quality Estimation Index (CQEI): An Improved Performance Criterion for Wireless Communications Systems Over Fading Channels

We introduce the Channel Quality Estimation Index (CQEI) as an alternative improved performance criterion of wireless communications systems operating over fading channels, directly related to the system's average error rate. CQEI is simple to evaluate, since it depends on the channel statistics, which vary much more slowly than the channel state itself, and thus can be obtained at the initialization state using a long training sequence and continuously improved during the whole communication period. As an application, we use CQEI to find the optimum number of branches in equal gain combining (EGC) receivers, operating over non-identical fading channels. Numerical and simulations results show that CQEI represents an efficient and easy to evaluate criterion to assess the performance of wireless systems.