59 Phase Estimation Based Channel Equalization Technique for 64-QAM Communication

Small scale fading causes severe fluctuations in the received signal strength. So, accurate channel estimation and equalization of the received signal is one of the most challenging problems of wireless communication. In this work, the performance of 64-QAM under fading condition is analyzed and efficient adaptive equalization technique is implemented using LMS algorithm. The Bit Error Rate (BER) of 64-QAM is determined after passing it through flat Rayleigh fading channel. Unlike conventional channel estimation techniques, such as PSAM, gradient approach is found to be more effective when input symbol constantly changes. By Law of large numbers we have considered that impulse response of the channel has almost unity amplitude and concentrated on estimating the phase of the channel coefficient. Here, the incoming symbols to the channel are constantly changing causing the behavior of the channel to vary according to the data. In gradient approach we estimate the channel using incoming symbols alone. The simulated results are found to be in good agreement with the theoretically determined results.