Multi-user Mimo System Interference Management Research

Since MIMO can substantially increase the channel capacity and improve the communication quality, it has been accepted as one of the key techniques for the future wide-band wireless communication. Recently, more and more schemes have been proposed for signal processing and space-time coding for single-user MIMO (SU-MIMO), research on it are close to saturation. But we should face a more practical question:how to solve the problem of user interference in multi-user MIMO (MU-MIMO) systems.When channel state information is known at the transmitter, precoding technology is a very effective means to solve the problem of user interference. With this fact in mind, the precoding technique in multi-user MIMO system is explored. We consider a multiple-antenna multi-access scenario where multiple antennas have been used to suppress the interference from other users. Applying a linear transformation based on the singular value decomposition (SVD) theorem to the codeword before transmission, the transmit vectors of each user are orthogonal and the performance of the MIMO system can be improved significantly using precoders.Multi-user detection at the receiver can weak the multi-user interference. Partial interference cancellation (PIC) group decoding, which groups the transmit symbols and decodes them independent after interference cancellation, have low symbol-error-rate (BER). For single user MIMO systems, full diversity can be achieved by space-time code design with low complexity PIC group decoding. In the thesis, we apply PIC group decoding algorithm in the design of multi-user layered space-frequency coded MIMO-OFDM system. Then the receiver can separate symbols and decode the signals of each user independently, and the decoding complexity of layered space-frequency code improved substantially.