分布式波束成形下的中继协作研究-通信与信息系统专业论文.docx

Abstract Abstract IV IV allocation between data transition and information feedback phase is proposed to maximize the upper bound of data transmission rate. Simulations show that the proposed scheme can improve data rate and relay number is limited by feedback error. In more-relay selection system, we discuss index mapping in feedback phase and propose a low-complexity designing method to maximize the received SNR at the destination. Theoretical analysis and simulations show that the proposed index mapping can obtain higher SNR than random index mapping and SNR loss induced by feedback error grows linearly with feedback error probability. In distributed beamforming system, beamforming codebook is designed to maximize the received SNR. Due to high complexity of the optimal codebook, a low-complexity method to design codebook is proposed based on vector quantization (VQ) codebook. Simulations show that the proposed codebook outperforms VQ codebook. Finally, in multiple-user cooperative networks, interference between users is the major problem of influencing data transmission rate. Distributed beamforming is utilized to cancel the interference in this dissertation. Compared to MIMO systems, due to limited resource and independently decoding the received signals at relays, relays cannot completely cancel the interference in Multiple Access channel-Broadcast channel (MAC-BC) scheme. Therefore, we focus on interference alignment with distributed beamforming at relays. Condition on users and relay antennas, the least relay number is given to achieve degree of freedom (DoF) of interference channel. The beamforming vectors are also obtained and optimized to improve system performance. Simulation shows the proposed scheme can achieve DoF of interference channel with the least relays and efficiently improve data transmission rate. Key Words: cooperative communication, feedback error, power allocation, distributed beamforming, Demodulate-and-Forward, index mapping, interferenc