Research On Power Optimization Technologies In Cooperative Transmission Systems

Along with the explosive increase of smart mobile terminals and multimedia services, the mobile communication system is facing new challenges, such as the shortage of wireless resources, low efficiency of spectrum usage, not enough data transmission rate, heterogeneous coverage, poor user experience and so on. In order to meet the requirements of next generation telecommunication system, extensive research has been done on cooperative communications by both academic and industry field, which has been standardized in3GPP (3rd Generation Partnership Project) as key technologies. Meanwhile, since the huge increase of wireless equipment and traffic load, the intense energy consumption will be a bottleneck of the future mobile communication development. Currently green communication has received wide attention of both academic and industry field. Researchers begin to focus on combining renewable energy resources, such as solar energy, wind energy, bioenergy and so on with conventional wireless communication systems. As one of those renewable energy resources, energy in microwaves, which is used to transfer information, has attracted many knowledgeable researchers’ attentions on simultaneous information and power transfer from the information theoretic perspective. At the background of low resource utility, high complexity and ever increasing energy consumption of mobile communication system, and supported by both vertical and horizontal research programs of our lab, we have done research on power allocation optimization technologies in cooperative transmission systems, which includes two key research points:1. Combined power allocation with precoding scheme in coordinated multi-point multiuser MIMO system based on joint processing mode.2. Power allocation algorithms in multiuser MIMO downlink systems for simultaneous information and power transfer.This dissertation presents a systematic research and illustration of cooperation transmission systems and precoding schemes. Cooperation transmission is a board conception, this dissertation mainly focus on multi-user cooperation, coordinated multi-point transmission. As to precoding research, we focus on non-codebook-based techniques and studied several precoding schemes based on Zero Forcing criterion and Minimun Mean Square Error criterion.In the first research point, we proposed a novel linear precoding scheme for CoMP MU-MIMO downlink systems based on JP mode. By carrying out an innovative channel extension approach and a matrix decomposition method with lower complexity, this precoding algorithm suppresses noise and multiuser interference (MUI) simultaneously and there is no additional requirement on the system’s configuration in terms of the number of antennas for each user. We also introduce a suboptimal power allocation scheme under the total power constraint of all the base stations. Complexity analysis and simulation results show that the proposed precoding algorithm can achieve elaborate performance while offering lower computational complexity. In the second research points, simultaneous wireless information and power transfer (SIPT) in multiuser MIMO downlink systems is studied. The combination of wireless energy transfer and traditional wireless communication techniques has been widely researched in order to release the high energy consumption dilemma and the limitation of battery supply for communication terminals. We built a system model for MU MIMO systems with simultaneous wireless information and power transfer, described the optimization problem, presented the boundary of the rate-energy (R-E) region and at last proposed a novel power allocation algorithm based on convex optimization theory, which is a rational compromise between system capacity and energy collection.