Study On The Limited Feedback Technique In Mimo System

Wireless MIMO (Multiple Input Multiple Output, MIMO) communication system, which uses multiple transmitting and receiving antennas to transmit and receive data, is able to combat multi-path fading in the hash wireless communication environment. Moreover, under the band width and power constraint, the capacity of a MIMO system is linear proportional to the minimum number of the transmitting and receiving antennas. Since the spectrum efficiency is improved significantly by the MIMO technology, it has been widely accepted as the core technology of the B3G or 4G wireless communication.Considering the limited feedback channel capacity achieved by practical communication system, the transmitter can't get the whole channel state information (CSI). Therefore, studying the limited feedback MIMO system has theoretical significance and application value. The subject of this dissertation focused on how to feedback and use partial CSI in the limited feedback MIMO system and the contents of the work are listed as follows:1. The multi-user limited feedback MIMO system using zero-forcing beamforming is further studied in this dissertation. On the basis of being familiar of the MIMO system model and the capacity achieved by the MIMO system in all kinds of channels, this dissertation further analysis the SINR of the MIMO system, then simulates the channel capacity achieved by the MIMO system in all kinds of limited feedback technique.2. A scheme of variable length coding is proposed in this dissertation, which is employed in multi-user limited feedback MIMO system using zero-forcing beamforming in the slow fading channels. In the certain slow fading channels, the proposed scheme outperforms multi-user MIMO system employing quantization-based combining in terms of sum capacity, with the same average feedback bits needed.3. The multi-user limited feedback MIMO-OFDM system using zero-forcing beamforming is further studied in this dissertation. The scheme of variable length coding proposed by this dissertation is employed in the MIMO-OFDM system based on pilot. It is demonstrated that the scheme of variable length coding outperforms the scheme of subspace tracking algorithm.