Differential codebook for general rotated dual-polarized MISO channels

It is crucial to have accurate channel state information at the transmit side to achieve the maximum performance in multiple-input multiple-output (MIMO) systems, especially for multi-user systems. Frequency division duplexing systems based on limited feedback facilitate this, but these techniques are reliant on carefully design codebooks that are optimized for various antenna deployment scenarios. In this paper we discuss the channel model for rotated-dual-polarized (RDP) antenna systems and propose an efficient way of designing practical differential codebooks for RDP scenarios. We assess the performance of the proposed differential codebook design technique by simulations, and it is shown that codebooks designed by the proposed technique outperform conventional fixed and differential codebooks with small number of codewords.