Analysis and optimization of pilot-symbol-assisted-modulation M-QAM for OFDM systems

In this paper, the current analysis focuses on the influence of demodulation performance in multipath fading propagation environments, which results from the pilot power variation of pilot symbol assisted modulation (PSAM) M-QAM in orthogonal frequency division multiplexing (OFDM) systems. The pilot-to-data power ratio (PDR) is optimized analytically, the loss due to imperfect channel estimation is calculated, and the probability is presented. Theoretical and simulation results show that the optimum PDR is affected by the signal-to-noise ratio (SNR), Doppler frequency and interpolation size etc. When the optimization parameter of PDR is used, the power of system transmission is minimum while still meeting a fixed bit error rate (BER) target, meanwhile the system can obtain to accurate channel estimation.