An easy-to-implement dual codebook for multiuser MIMO systems

The complex multiplication between data streams and codebook when precoding at the transmitter always needs a lot of computing units in hardware implementation. In this paper, we first propose a binary-based codebook, in which all elements in the precoding matrix are expressed in power of 2. The proposed method can reduce practical engineering implementation complexity significantly, since the multiplication between the data symbol and the element of the codebook matrix can be regarded as a simple binary shift of the transmission data. This approach can be applied in various existing codebook design methods and we also consider on the multi-user case. But the operation is bound to bring in some accuracy loss because we hardly obtain the optimal codebook right with expression of power of 2. Then we propose a novel dual-codebook scheme which is easy to implement and can make up the performance penalty. The simulation results reveal that the proposed scheme outperforms 3GPP R10 LTE-A DFT (discrete Fourier transform) codebook and ease the burden of implementation cost.