Performance analysis of hybrid selection and closed-loop transmit diversity systems in the presence of feedback delay

The paper investigates the effect of feedback delay on hybrid selection and closed-loop transmit diversity in Rayleigh time- selective flat fading. A Jakes model was used to formulate channel state correlation as a function of feedback delay and a Markov model was used to characterize channel state evolution. According to these models, the receive SNR is obtained. Averaging the receive BER over the probability distribution of error vector and optimal channel vector respectively, the closed-form expression on the average BER of the systems was derived. The expression gives the relationship between performance degradation and feedback delay. Simulation results verify the theoretical calculation and present the varying curve of performance loss as the feedback delay increases.