Impact of Uncertain Channel Estimation and Outdated Feedback on the Adaptive M-PSK Modulation

This paper investigates an adaptive M-ary phaseshift keying (M-PSK) modulation scheme over Rayleigh flat fading channels. The data rate is adapted according to the channel state. At the receiver, the fading is estimated using pilot symbols. To cancel the channel impact, we correct the received signal by dividing it by the estimated value of the fading. So, we propose to adjust the modulation level by examining the statistics of the corrected signal. In contrast to the previous works on the adaptive M-PSK modulation techniques, our modulation switching protocol takes into account the channel estimation error variance. Moreover, we derive a new closed-form expression for the average bit error rate of the considered system