On Angle Feedback and Antenna Shuffling in Double Space-Time Transmit Diversity Systems

In this letter, we compare angle feedback and transmit antenna shuffling schemes for double space-time transmit diversity (DSTTD) systems with four transmit antennas and at least two receive antennas. We show that a DSTTD system with one bit of angle feedback does not provide better performance than the same system with one bit of transmit antenna shuffling. We also present a simplified general result about the selection of antenna shuffling matrix from six permutation matrices to facilitate our arguments. In simulation, we observe that antenna shuffling outperforms angle feedback in i.i.d. Rayleigh fading channels.