Low speed feedback for grassmannian beamforming in MIMO-OFDM with frequency selective channel

Multiple input multiple output (MIMO) precoding is an efficient scheme that may significantly enhance the communication link. Many precoding schemes require channel knowledge at the transmitter that is obtained, in non-reciprocal channels, through feedback from the receiver to the transmitter. Focusing on the natural fusion of orthogonal frequency division multiplexing (OFDM) and MIMO, we exploit the channel correlation in the frequency domain to reduce the required feedback data rate. The proposed feedback method tailors Huffman coding to an existing clustering method, and is employed here for the transmit beamforming. The method leads to a significant reduction in the required feedback data rate, and performs better than existing feedback techniques. The proposed method can be easily implemented in any existing or future protocol due to its low complexity.