Research On The Optimal Policy Of Resource Allocate In Multi-Carrier System

Data transmission in the mobile channel with high speed and reliability is required in future mobile communication system. The 4th mobile communication system is expected to provide high-quality broadband services using the minimum possible resources (power, bandwidth, complexity). Toward this end, an appropriate transmission technique that matches the mobile channel characteristics is required. Taking many uncertain factors in mobile communication channel into account, OFDM (orthogonal requency-division multiplexing) is one of the promising techniques that meet such requirements with reasonable complexity. OFDM is one of multi-carrier digital modulation techniques, in which a single high rate data stream is transmitted using a number o lower data rate sub carriers, it has many properties, such as robustness to multi-path fading, high data rate transmission capability with bandwidth efficiency, and so on.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 studies 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 real-time traffics is proposed, which minimizes the required transmit power while guaranteeing the QoS requirement of real-time traffics. In addition, a proportional fair resource allocation algorithm is proposed for non-real-time users, which aims to achieve the highest system throughput under the constraints of overall power and fairness among users. For grouping OFDM systems, a fast sub channel allocation algorithm is firstly developed. Then, an exponential granularity OFDM system and its related sub channel grouping and allocation algorithm are presented.