Blind SLM for PAPR reduction of Alamouti DSFBC systems

The combination of differential space-time block codes and orthogonal frequency-division multiplexing (OFDM) as differential space-frequency block coded (DSFBC)-OFDM system is a good candidate to achieve maximum diversity without the need to channel estimation. High peak-to-average-power ratio (PAPR) is a major drawback in these systems. The available PAPR reduction methods are not directly applicable in DSFBC-OFDM system. In this study, the proper application of selected mapping (SLM) method for reducing PAPR in Alamouti DSFBC-OFDM system is investigated and two different schemes are presented: conventional SLM (C-SLM) and blind differential SLM (BD-SLM). In C-SLM technique, the index of the selected phase sequence must be sent to the receiver side as the side information (SI). In the proposed BD-SLM method, specific phase mask vectors are generated with one-to-one correspondence with the different phase rotation sequences. Then at the receiver side, a differential minimum Hamming distance decoder is introduced to detect the index of optimum phase mask vectors without SI. Simulation results show that the proposed BD-SLM scheme (without the need to SI) provides good performances of both the bit error rate and PAPR reduction compared with C-SLM method.