Investigating the Performance of Pilot Aided Channel Estimation in Amplify and Forward Cooperative Wireless System

Abstract

Investigations on the performance of pilot aided channel estimation in amplify and forward orthogonal frequency division multiplexing (AF-OFDM) based cooperative wireless system is presented. The quest for a reliable and high rate of data transmission over Rayleigh fading environment has necessitated the need to estimate the channel condition of a communication system. The effect of block type channel estimation using the least square estimator (LS), and minimum mean square error (MMSE) algorithms were evaluated in term of bit error rate (BER). In cooperative wireless system, the source node generate an analogue signal which is then converted using analogue to digital converter (A/D) and then transmitted using OFDM system with the insertion of pilots and data as training sequence to enhance the quality of the signal at the relay and destination nodes. At the relay node, the signal received is converted using digital to analogue converter (D/A) and then amplified and forwarded to the destination where the channel estimation process is also performed, and the destination node estimate and combine the signals received. Simulation results obtained using 4-QAM,16-QAM, 32-QAM and 64-QAM show that, the BER values decreases as signal to noise ratio (SNR) increases for LS and MMSE but at higher SNR, MMSE outperforms LS estimation algorithms.