An Iterative CFO Compensation Algorithm for Distributed Spatial Modulation OFDM Systems

Spatial Modulation (SM), conveying data bits via the antenna-activation process, is a novel modulation technique for multiple-input multiple-output (MIMO) systems. SM can be combined with orthogonal frequency division multiplexing (OFDM) to improve the reliability, quality and capacity of transmission. However, SM OFDM systems also inherit from OFDM systems the drawback of high sensitivity to carrier frequency offset (CFO), especially in distributed MIMO environment where the CFOs of all transmit antennas are different. To overcome this problem, in this paper, the CFO characteristics of distributed SM OFDM systems are studied and a new iterative CFO compensation algorithm which exploits the interference effect caused by each antenna´s CFO is proposed. Moreover, the information-conveying feature of SM system is applied to the proposed CFO compensation algorithm to reduce the computational complexity and provide fast compensation of CFOs. Simulation results show that the proposed CFO compensator achieves considerable performance improvement with low complexity.