Iterative carrier frequency offset estimation and compensation for OFDMA uplink

This paper presents a method to counteract the detrimental effects of carrier frequency offsets (CFOs) in the uplink of OFDMA-based wireless networks. The CFO values of different users are first estimated from the received decomposed signal using the best linear unbiased estimator (BLUE). The CFOs effects are then compensated based on the estimated values and also taking advantage of an iterative parallel interference cancellation (PIC) scheme. A novel contribution of this paper is introducing an iterative concatenated estimation and compensation algorithm for suppressing the residual interference due to imperfect estimators. The introduced method is successful where the estimator converges after only one iteration with a significant improvement in estimation accuracy. Also very close BER performance results can be achieved to that of systems with perfect knowledge or without CFOs particularly at practical SNRs.