Frequency offset mitigation of cooperative ofdm system in wireless digital broadcasting

Mobile digital broadcasting is expected to become a promising application in future wireless communication. To improve the system performance in limitation of size and cost, the OFDM and MIMO techniques are adopted. Recently, cooperative diversity techniques are developed to be a solution. In this paper, we propose the carrier frequency offset mitigation scheme in cooperative communication using multi-symbol encapsulated orthogonal frequency division multiplexing (MSE-OFDM), in which one cyclic prefix (CP) is used for multiple OFDM symbols. We use the FFT size-reduced MSE-OFDM system which can be used to reduce the peak-to-average power ratio (PAPR) and improve the robustness to carrier frequency offset. The cooperative communication uses not only direct path from source to destination but also indirect path via relay station. Each different relays require more precise frequency synchronization and lower PAPR, so we adopt the MSEOFDM to increase the system performance. The performance analysis of cooperative MSE-OFDM in multipath fading channels has been done and the effect of carrier frequency offset and PAPR have been studied.