Packet Scheduling in the Presence of Channel Estimation Error in Multi-User OFDM Wireless Systems

In this paper, we investigate the performance of a packet-based multi-user orthogonal frequency division multiplexing (OFDM) wireless system in the presence of channel estimation error. To this end, we consider the use of two channel estimation schemes for coherent demodulation; one is a simple linear and the other is an optimum Wiener-type channel estimator. We examine the effect of channel impulse response (CIR) estimation error on the coherent reception and then the effect of signal-to-interference and noise ratio (SINR) estimation error on channel aware transmission techniques (e.g., packet scheduling). It is shown that the performance of coherent reception is relatively less susceptible to the CIR error, but the performance of channel aware schemes can be very sensitive to the SINR estimation error, mainly due to incorrect scheduling. To alleviate this problem, we propose a scheduling scheme which can work without significant performance degradation in the presence of large channel estimation error. Finally, we verify the performance of the proposed scheduling scheme by computer simulation