Researches To Resource Allocation Algorithms Of Relay Networks

With the development of the Wireless Communication, uses'requirements to Quality-of-Service (QoS) of Wireless Communication Networks are higher and higher. Although the User Terminals have more and more traffic functions, their limited sizes still affect the application of many technologies for improving the capacity of networks, such as the Multi-Antenna technology and so on. Therefore, the Communication Industry votes the Relay Cooperative Communication to satisfy users'requirements. That is an important technology to solve the contradiction between the high rate requirement and the User Terminals'limited sizes.Many problems which have been existing in traditional networks for a long time, such as poor flexibility, bad robustness and so on would be solved in Relay Networks. Thus, researches to Wireless Relay Networks have become hot points. This dissertation mainly researches resource allocation algorithms in the relay system. And OFDM based relay network and OFDMA based relay network are the objects of our research on resource optimization.Firstly, resource allocation algorithm in OFDM based relay network is studied. In non-regenerative two-hop relay system using OFDM modulation, optimal power allocation strategy combining source node and relay node is proposed in the case that the sum power of source node and relay node is constrained, given theory analysis and specific implementation. Since the subcarrier pairing issue is related in the relay system using OFDM modulation technology, a joint optimal power allocation and subcarrier pairing algorithm is presented. Compared with several existing algorithms by simulation, the proposed algorithm in this dissertation improves the channel capacity in the relay cooperative system more effectively.Secondly, resource allocation algorithm in OFDMA based relay network is studied. Adaptive resource allocation algorithm is proposed, which divides the resource allocation issue into two steps to fulfill, including subcarrier pairing and adaptive power allocation. Compared with the fixed subcarrier pairing and equal power allocation algorithm by simulation, adaptive resource allocation algorithm brings gains to system capacity more effectively. And the system capacity increases as the number of users increases. Based on the algorithm, an improved adaptive resource allocation algorithm is presented, allocating the lengths of BS subframe and RS subframe with the instantaneous channel statement information dynamically. Compared with the adaptive resource allocation algorithm by simulation, the improved adaptive resource allocation algorithm brings more capacity gain. Especially when the SNR is larger than 13dB, the improvement of the performance is more obvious.