关键词: 协作通信, 空频码, 载波频率偏移, 正交频分复用技术

Abstract: To combat synchronization errors in cooperative communication，Orthogomal Frequence Digital Multiplexing（OFDM） technique is applied to achieve the full cooperative diversity and full multipath diversity for asynchronous cooperative communications，in which a kind of Space-Frequency（SF） code is used at relay nodes.Although OFDM can combat timing errors，it is very sensitive to Carrier Frequency Offset（CFO）.For cooperative communication，multiple CFO makes frequency compensation difficult if not impossible.By exploiting the structure of the SF code and energy distribution characteristics of Inter-Carrier Interference（ICI），this paper proposes re-ranging the SF code at transmitter and multiple frequency shifts with corresponding FFT at receiver to combat multiple CFO effectively.Based on this，by using Q tap method，it gets a performance to close Minimum Mean Square Error（MMSE） at the cost of lower algorithm complexity.

Key words: cooperative communication, Space-Frequency（SF） code, Carrier Frequency Offset（CFO）, Orthogonal Frequence Digital Multiplexing（OFDM）