Signal Detection for Space-Frequency Coded Cooperative Communication System with Multiple Carrier Frequency Offsets

To combat synchronization errors in cooperative communication, paper (Li, 2006) applied the orthogonal frequency division multiplexing (OFDM) technique to achieve full cooperative diversity and full multipath diversity for asynchronous cooperative communications, where a kind of high rate space-frequency (SF) codes was used at relay nodes. However, OFDM is very sensitive to carrier frequency offset (CFO). For conventional communication system, only one CFO exists and its effect is easy to be compensated. But for cooperative communication, the CFO between each relay and destination may be very different. These multiple CFO make frequency compensation difficult if not impossible. To solve this problem, we propose a detection scheme for SF codes which can work much better than the conventional SISO zero-forcing (ZF) and minimum mean square error (MMSE) methods. Moreover, parallel interference cancellation (PIC) can be used to further improve the system performance. Simulation results show that the proposed scheme combined with PIC is capable to achieve almost the same performance as cases without CFO.