A low complexity receiver for OFDM-IDMA with multiple carrier frequency offsets

The performance of orthogonal frequency division multiplexing interleave division multiple access (OFDM-IDMA) systems would be severely degraded by the inter-carrier interference (ICI) which is caused by multiple carrier frequency offsets (CFOs). Existing receivers with CFO mitigation capabilities either have extremely high complexities or suffer from performance loss compared with the conventional receiver in the absence of CFOs. In this paper we propose a new receiver suitable for OFDM-IDMA in the presence of multiple CFOs. By properly performing soft interference cancellation (SIC) and variance approximation, the proposed receiver is capable of completely eliminating the CFO effects with a much lower complexity which is comparable with the zero CFO case. Both signal-to-interference-plus-noise ratio (SINR) and complexity analysis are conducted to theoretically validate the idea of the proposed receiver. Simulation results are also presented to compare the proposed receiver with existing ones. It is shown that the proposed receiver is a strong candidate for OFDM-IDMA with CFOs in practice.