A Robust Joint Frequency Offset Estimation for the OFDM System Using Cyclic Delay Diversity

摘要

Cyclic delay diversity (CDD) is a low-complexity transmit diversity technique for orthogonal frequency division multiplexing (OFDM), which transforms a multiple-input channel into an equivalent single-input channel with a large delay spread. Consequently, high frequency selectivity makes channel and frequency estimation a challenging task. This paper proposes an improved joint estimation of carrier frequency offset and sampling frequency offset for the OFDM system using CDD technique. By finding the amount of a transmitantenna specific delay which reduces the variance of the frequency estimation scheme, these parameters improve the robustness of the joint frequency estimation scheme against the frequency selectivity of the channel. Computer simulation shows that the joint frequency-offset estimation scheme with properly designed cyclic delay parameters performs robustly, with the performance better than the conventional scheme.