Constellations Rotation for Quaternion Quasi-rthogonal Space Time Block Code in Keyhole Channel

 A new kind of constellations rotation for quaternion quasi-orthogonal space time block code (QQOSTBC-CR) in keyhole channel is proposed. These codes can transmit and receive through dual-polarized antennas respectively. The QQOSTBC with eight transmit antennas are designed firstly. And pair-wise decoding algorithm is adopted for N=8. Finally, it is compared the QQOSTBCCR with the QOSTBC-CR (Constellation Rotation Quasi-Orthogonal Space Time Block Code) and QOSTBC (Quasi-Orthogonal Space Time Block Code）in the case of keyhole channel, and with the QQOSTBC-CR in the case of Rayleigh channel. Simulation results show that the new QQOSTBC-CR can provide a gain of 4.5dB/7dB than the QOSTBC-CR at the given BER of 10^-3 for BPSK/QPSK in the condition of four transmit antennas and keyhole channel, the new QQOSTBC-CR can provide a gain of -4dB/-3dB than the QQOSTBC-CR in the case of Rayleigh channel for BER=10^-3