A Robust Turbo Coder Design For Channel Maximization In MIMO OFDM With Cognitive Radio System

In this paper, we study the turbo coder design problem for MIMO-OFDM systems with insufficient cyclic prefix (CP) using statistical channel state information (CSI) at the transmitter. In our previously proposed channel independent turbo coder scheme, an interference nulling based turbo coder structure is studied, which can assist to either cancel inter-block interference (IBI) or separate the subspace engaged by IBI from the subspace used for information symbols. In this work, we consider a robust turbo coder design which combines statistical CSI at the transmitter and the interference nulling based turbo coder arrangement to gain a better performance compared to the channel independent turbo coder scheme. OFDM (Orthogonal Frequency Division Multiplexing) has been chosen as the air interface technique for LTE (Long Term Evolution) standard. However, OFDM system is sensitive to synchronization errors generated by multipath delay, Doppler shift and oscillator instability. In this paper, we address the synchronization problem between the transmitter and the receiver is done. Time-domain synchronous orthogonal frequency division multiplexing (OFDM) has advantages in spectral efficiency and synchronization. However, its iterative interference cancellation algorithm will suffer from performance loss especially under severely fading channels with long delays and has difficulty supporting high-order modulations like 256 QAM, which may not accommodate the emerging ultra-high definition television service.