Course Frequency-Offset Acquisition via Subcarrier Differential Detection for OFDM Communications

An effective frequency-offset acquisition technique based on differential detection for wireless orthogonal frequency-division multiplexing communication is investigated. By exploiting differentially coherent detection involving coherent cross-correlation extraction and subsequent differential detection, data-aided frequency acquisition assisted by frequency-domain pseudonoise matched filters reduces probabilities of false alarm and miss over a propagation channel with a sufficiently wide coherence bandwidth. Furthermore, the proposed technique uses the inherent frequency diversity with maximum ratio combining, and exploits subcarrier-level differential detection and subsequent coherent cross-correlation accumulation. To realize the subcarrier-level differential-detection approach proposed here, the -lock sequence must be modified by taking into consideration the self-interference caused by Rayleigh fading, and the out-of-lock sequence must be remodeled by means of the discrete Wiener process. Statistical analysis and extensive computer simulation verify the superiority of the proposed technique.