Research On Enhanced Mimo For Imt-advanced

3G wireless communication system is being widely used in the world, and research work of B3G,4G wireless communication systems are being intensively carried out. The4G communication system adopts MIMO transmission as the key physical layer technique to meet the requirements of.high data rates in future communications. Various kind of MIMO enhanced techniques are researched for4G based on traditional point to point MIMO. The MU-MIMO (Multi-User MIMO) and CoMP (Coordinated Multiple Points) are two hottest points in research and standardization work. They have been treated as basic MIMO transmission techniques in4G standardization LTE-A proposed by3GPP.This thesis research on these two key MIMO enhanced techniques, which are MU-MIMO and CoMP. Detailed researches include channel feedback technique of MU-MIMO, multi-user selection technique as well as coordinated resource allocation technique. The main contributions and innovative research findings of this thesis are listed as follows:1. For the downlink CSI (Channel State Information) feedback of MU-MIMO, the codebook extension feedback technique is proposed. Two codebook vectors are fed back without channel the codebook structure and the CSI accuracy is enhanced by the weighted sum of the two codebook vectors as it increases the covering space of codebook. It has2advantages:(1) the increscent CSI accuracy need not new codebook design, so it holds forward compatibility and simple codebook design in update system;(2) the two codebook vectors focus on SU-MIMO (Single-User MIMO) and MU-MIMO respectively, so the base station can effectively perform dynamic SU/MU MIMO switching and ensure the flexible of scheduling.2. For the MU-MIMO SNR (Signal to Noise Ratio) estimation, the maximum MU-MIMO SNR base on ZF (Zero-Forcing) precoding is derived. The MU-MIMO feedback scheme is proposed based on the SNR, which is mapping to CQI (Channel Quality Indicator). The scheme increases the MU-MIMO CQI accuracy, and hence the MU-MIMO performance is enhanced.3. For single cell MU-MIMO user pairing, a novel user selection switch (USS) feedback scheme and related user selection procedure are proposed. It derives MU-MIMO performance, which is base on ZF (Zero-Forcing) precoding and adopts fixed codebook in CSI quantization, for different number of paired users. Through this USS feedback, BS can avoid large inter-user interference in pairing user. Hence it solves two problems in low rates fixed codebook feedback. The two problems are:(1) MU-MIMO performance is not increase with the feedback bits increasing;(2) the MU-MIMO performance gain compared with SU-MIMO is decreased with the received SNR (Signal Noise Ratio) increasing.4. For multi-user CoMP transmission, the MU-MIMO transmission in CoMP scenario is divided into four typical pairing forms. Series user pairing criteria are designed for different form based on received SINR (Signal to Interference Noise Ratio) characteristic and channel Correlation characteristic of MU-MIMO and CoMP transmission. The rounded user pairing procedure and algorithm is proposed for actual CoMP MU-MIMO transmission based one these criteria.5. For CoMP transmission resource allocation, the optimal sub-band cooperated power allocation strategy among sub channels is derived base on single antenna downlink coordinated transmission in frequency selective channel. The strategy derived local optimal solution through Lagrange method aim at maximum transmission rate. A fast search method is proposed base on characteristic of optimal solution and the search overhead is largely reduced, from2dimensions to1dimension.