Resource Optimization In Multi-carrier And Cooperative Communication Systems

With the rapid growing of wireless applications, the conflict between the limited wireless resource and the increasing Quality of Service (QoS) requirement of multimedia traffics becomes more and more urgent. It involves various technologies from different layers of wireless systems to reconcile the conflict. At the physical layer, Orthogonal Frequency Division Multiplexing (OFDM) is an efficient capacity approaching technique for broadband wireless systems;Cooperative communication is a recently developed capacity enhancement method, which can effectively increase the capacity and robustness of wireless systems. At the data link layer, resource optimization is a vital way to increase the system throughput and the utilization of wireless resource while providing the QoS requirement of multimedia traffics. In this dissertation, under the guidance of multiuser information theory, the resource optimization techniques in both OFDM systems and cooperative communication systems are intensively studied. The contents of this work are listed as follows:Power is the most important resource for wireless systems and the water-filling method is the optimal power allocation method for independent parallel channels. Thus, various water-filling methods are firstly studied in this dissertation, including water-filling for multicarrier systems, time domain water-filling and multiuser water-filling. Especially, the water-filling method with the integer bit constraint is researched and a modified greedy method and a bisection bit allocation method are proposed, respectively. Based on this, a multiuser water-filling method for parallel multiple access channel is presented.The subcarrier, bit and power allocation in OFDM system is studied in the second part. Firstly, a novel concept of marginal utility of a subcarrier is developed, based on the interconversion of the subcarrier and power. After that, a resource optimization method for realtime traffics is proposed, which minimizes the required transmit power while guaranteeing the QoS requirement of realtime traffics. In addition, a proportional fair resource allocation algorithm is proposed for non-realtime users, which aims to achieve the highest system throughput under the constraints of overall power and fairness among users. Furthermore, the resource allocation for heterogeneous traffics is studied. An optimal algorithm is proposed to determine the overall subcarrierand power allocation for realtime traffics, as well as a computationally efficient subop-timal algorithm. For grouping OFDM systems, a fast subchannel allocation algorithm is firstly developed. Then, an exponential granularity OFDM system and its related subchannel grouping and allocation algorithm are presented. In addition, we consider the antennas in MIMO-OFDM systems as a kind of resource, and develop a joint antenna selection and subchannel allocation algorithm.The resource optimization in cooperative communication systems is studied in the third part. A novel cooperative ARQ protocol is firstly developed, which utilizes the limited feedback from the destination and combines the incremental relaying with selection relaying. The packet loss rate and the throughput efficiency of the cooperative ARQ protocol are theoretically analyzed. Furthermore, we take the cooperative partners as resource and propose an optimal partner selection algorithm for cooperative ARQ protocol in multiuser networks, which is based on the bipartite graph matching. The optimal power allocation for cooperative relaying channels is also studied. The concept of equivalent channel gain model for cooperative relaying channels is developed, for both AF and DF relaying modes. Based on this, a time-domain water-filling power allocation method is proposed. We then study the resource optimization in OFDM relaying channels and propose a suboptimal joint cooperative subcarrier pair selection and power allocation algorithm.