Multiple Carrier Frequency Offsets Estimation in Cooperative OFDM Systems

Frequency synchronization plays a critical role in acquiring cooperative diversity for cooperative OFDM systems. However, the superposition of different carrier frequency offsets (CFOs) among each relay and destination makes the estimation difficult. In this paper, a novel multiple CFOs estimation algorithm is proposed. With this algorithm, the CFO corresponding to each relay can be accurately estimated through eliminating the inter-node interference caused by other relay nodes´ CFOs. Simulation results show that the proposed algorithm works well, and the mean square error of which is close to the Cramer-Rao lower bounds.