Research On The Resource Management And Optimization Technology For Wireless Cooperative Communication Systems

With the fast development of wireless access technology and continuously emerging of many new applications of wireless data service, not only the wireless spectrum demand increases sharply, but the transmission rate that the network can provide is put forward higher requirement. As the available spectrum resources are limited, the next generation wireless communication system must adopt more advanced algorithms and techniques to improve the spectrum efficiency and meet the growing demand of the user’s transmission rate. In collaborative communication technology, nodes with one antenna can utilize antennas of other nodes to form a virtual antenna array to obtain the diversity and multiplexing gain through node’s cooperation which can combat multipath fading and decrease inter-cell interference. Due to this, user’s transmission rate and system’s spectrum efficiency can be improved effectively which makes collaborative communication technology draw people’s more and more attention.In wireless collaborative communication system, one of the most important challenges is how to realize the resource management and optimization, such as collaborative node selection, subcarrier and power allocation, node’s spectrum sharing, and so on. Currently, quite a lot research institutions and researchers have done much work on wireless collaborative communication system and they have achieved a lot, however, various problems remain to be solved.In this dissertation, we have investigated relay node selection and resource allocation in wireless cooperative communication systems, the collaborative cell selection and resource allocation in CoMP systems and how the authorized user and the cognitive user share the same spectrum resource cooperatively and the corresponding power allocation in Underlay/Overlay spectrum share mode. We propose several innovative settlement mechanisms and further verificate the performance through theoretical analysis and simulation results. The main contributions of this dissertation are listed as follows:1. Propose one cooperative relay node selection and power allocation scheme based on a first price auction game aiming to increase the total system energy efficiency.Firstly, we propose an energy efficiency aim function which can consider the source node’s transmission rate and the corresponding consumed transmission power simultaneously which aims to decrease the total system energy consumption.Secondly, while giving an energy efficiency aim, we model the interaction between the source node and the relay node as a first price auction game model, when the source node needs help, it will choose the relay node which not only causes the minimum cost to it but also can ensure the minimum transmission rate for help.Thirdly, the power of the relay node which takes part in the cooperation will be got and the relay node will also gain some awards from the cooperation, and through reinforce learning, its awards will be maximized.Finally, the simulation results show that with the same energy efficiency aim, the proposed scheme can reduce the power consumption obvisously.2. Propose one collaborative cell selection, sub-carrier and power allocation scheme in downlink CoMP systemFirstly, fully considering the energy efficiency of the system, we propose one coordinated cell selection scheme, aims to choose the two most suitable cooperative eNBs for each cell-edge user.Secondly, while the cooperative eNBs are selected, we propose a novel sub-carrier allocation algorithm which can fully consider all the users’fairness, and in this sub-carrier allocation algorithm, the cell-center users and the cell-edge users can utilize the optimal sub-carrier resources according to their priorities which can ensure fainess.Thirdly, after all the sub-carriers allocated to the users, the corresponding power allocated to each user is calculated.Finally, simulation results show that the proposed scheme can not only improve the system’s energy efficiency and users’fairness but also all users’throughput in one sector.3. Propose a novel cooperative spectrum sharing diagram, and based on this diagram a distributed optimal power allocation algorithm for cognitive users is proposed.Firstly, we propose a novel cooperative spectrum sharing diagram for the authorized users and the cognitive users based on the spectrum occupancy of the authorized users and the cognitive users in Underlay/Overlay mode respectively, and in this novel spectrum sharing diagram, the cognitive users can utilize all the spectrum resources, including the spectrum allocated to the authorized users and the idle spectrum resource.Secondly, based on this novel spectrum sharing diagram, we consider the distributed power allocation problem and formulate the problem as a non-cooperative game.Thirdly, we get the solution of the Nash Equilibrium Problem and propose an optimal distributed power allocation scheme under this new spectrum sharing diagram.Finally, simulation results show that the proposed scheme can not only reduce the switching frequency and improve the spectrum utilization efficiency, but also can enlarge the system’s sum-rate.