Two adaptive diagonalization method for Double STTD system

In this paper, we deliver the diagonalization methods for the single user and multi-user D-STTD (Double Space Time Transmission Diversity) system. A single user D-STTD system is that one transmitter sends four streams to one receiver and a multi-user D-STTD system is that one transmitter sends four streams to two receivers. In the two scenarios, we utilize the special structure of H^HH of D-STTD system and split the precoding matrix W as W₁W₂ with known channel knowledge in the transmitter: at first, the anti-diagonal sub-matrix of H^HH has been diagonalized by W₁; in the second, the leaving element of symmetric structure matrix (HW₁)^HHW₁ has been diagonalized by W₂ through SVD or GSVD. Furthermore, the adaptive antenna shuffling has been introduced into multi-user D-STTD system to improve performance. Our methods in two systems all have significant performance gain which are proved by the simulation results: in the single user D-STTD system, our method has the same performance as SVD method and no special operation is needed in receiver; in the multi-user D-STTD system, our method has almost 2.0 dB gain than no precoding method.