Coarse frequency-offset acquisition via subcarrier differential detection for OFDM communications

An effective frequency-offset acquisition technique based on differential detection (DD) for wireless orthogonal frequency-division multiplexing communication is investigated. By exploiting differentially coherent detection involving coherent cross-correlation extraction and subsequent DD, 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 operation and subsequent coherent cross-correlation accumulation. To realize the subcarrier-level DD approach proposed here, the in-lock sequence must be modified by taking self-interference caused by Rayleigh fading into account, and the out-of-lock sequence must be remodeled by means of the discrete Wiener process. Statistical analysis and extensive computer simulation verifies the superiority of the proposed technique.