Efficient embedded signaling through Alamouti STBC precoders in MIMO-OFDM systems

Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) is a promising modulation scheme for high performance broadband wireless communications that suffers from a major drawback, which is the high Peak-to-Average Power Ratio (PAPR) of the output signals. In this paper, we propose a new blind combined Alamouti Space-Time Bloc Codes (STBC) approach inspired from the Selected Mapping (SLM) process to solve this PAPR issue for MIMO-OFDM systems. Our solution is based on a specific STBC patterns from which we construct precoding sequences forming a codebook that ensures the role of an inherent embedded signaling for the MIMO-OFDM system. Furthermore, in order to efficiently recover the transmitted sequence, we propose a set of decision schemes that banks on the Max-Log-Maximum A Posteriori (MAP) algorithm. To significantly improve the obtained results, we add another embedded signaling through a rotated and unrotated QAM constellation set. Both embedded signallings lead to a combined SLM-Alamouti technique for which we investigate a powerful decision process. We show that our proposed method guarantees a reliable and perfect signal recovery at the receiver side and dramatically reduces the PAPR level at the transmitter side. Simulation results are given to support our claims.