Research On Key Techniques Of Wireless Resource Management In OFDM System Based On Relaying

In recent years, along with the rapid development of the mobile communication, data communication and internet network, much more performance for the next generation of wireless communication network are desired by people. This new type of wireless communication network can not only provide users with high quality of QoS service, especially multimedia data with higher rate and lower delay, but also should has the characteristic of scalable network topology and low cast, which is exactly the business operators expect the future network to be. OFDM(Orthogonal Frequency Division Multiplexing) shows good resistance to multipath fading and leads to high frequency efficiency in wireless communication system, while relay can enlarge coverage and reduce the network cost, even if improve the channel quality when the relay is cooperative. The result that combination of OFDM and relay will be used in future wireless communication system has been generally authorized by the researchers and engineers.Efficient radio resource management plays a very important role in the design of wireless network, in the dissertation, we study the problems about wireless resource allocation and packet scheduling used in the ofdm communication system with relaying technology. We focus on the resource allocation for the relaying channel and the OFDMA enhanced cellular system, additionally, packet scheduling is studied for wireless Mesh backbone network. Lots of this research is supported by the National Basic Research Program of China (973 Program) No. 2007CB310604, National Natural Science Foundation of China No. 60772108 and the Program "The Research on Key Techniques in Wireless Mesh Network" cooperated with China Mobile Institution. The main contents of this thesis are as follows:After reviewing the development and challenges of wireless relaying communications, firstly, the resource allocation for wireless relaying channel is studied. For two-hop cooperative relaying channel, one subcarrier allocation algorithm is proposed, it could significantly improve system capacity both in AF and DF schemes based on the given power allocation methods, the complexity of this algorithm is also very low. Then, the resource allocation for multi-hop channel is studied under the constraint of system power. In order to maximize the system capacity, one joint power and subcarrier allocation strategy are explored by using of PGA(Partheno Genetic Algorithm). In AF scheme, the complex mathematic model of multi-hop system is changed into an equivalent one by induction method, optimal power allocation for multi-hop single-carrier system is developed by the methods of lagrange multiplier and power water-filling method, the proposed adaptive power allocation algorithm for multi-carrier system is applied in the joint allocation strategy and further enhanced capacity.Subsequently, we research resource allocation method for OFDMA cellular network with relaying in Chapter 4. Different from the general model, the wireless resource allocation model taking into account user QoS and fairness is established based on game theory and Nash Bargaining Solution(NBS). A suboptimal subcarrier allocation algorithm is proposed in accordance with NBS, it could grant the minimum rate of each user, and fairly allocate subcarriers to improve the system capacity at the same. An effective power allocation method is also studied after this subcarrier allocation work, the simulation results show that it could enlarge capacity greatly.Centralized wireless resource allocation methods are used in relay channel and wireless relaying cellular network above, distributed packet scheduling is studied for wireless Mesh backbone network with MRMC(Multi-Radio/Multi-Channel) in this dissertation. In chapter 5, each Mesh router is responsible for packet scheduling of all packets in its buffer. By using of the packet's routing information, a priority criterion is developed based on the crosslay optimization of MAC and Router, and wireless resource allocation method for MRMC is described. Simulation results show that the proposed packet scheduling method can effectively reduce the packet delay and packet loss probability.The final chapter gives the summary of this dissertation and emphasizes the valuable research directions for OFDM wireless system with relaying technology.