The Scheme of MIMO-OFDM Linear Precoding Based on CDD

MIMO linear precoding can transform relative MIMO channels into Ns independent virtual channels by precoding process in the transmitter and receiver, and is an effective MIMO multiplex mode to improve throughput. In this contribution the principle and system structure of MIMO linear precoding based on CDD is introduced. With the CDD based precoding, we can select the best precoding for the data channel not only based on the sum capacity metric but also based on the feedback reliability. By choosing a proper cyclic delay between a small delay (e.g., tau=2) and a large delay (e.g., tau=N_jji/N_t), we can efficiently adapt to the proper MIMO mode with a single unified precoding structure.