Research On Resource Allocation For Wideband Multicarrier Wireless Transmission

In future mobile communication system, the high transmission rate determines the choice of wideband transmission. In wireless channel, especially in terrestrial communication environment, with the increase of transmission rate, the multipath propagation effect would influence the quality of communication more seriously. Due to the high spectrum efficiency and strong ability to combat multipath propagation effect, multicarrier technique, e.g. OFDM, has received intense attention. In this paper, the resource allocation problem of wideband multicarrier wireless transmission system is discussed to realize the optimal allocation of system resource, i.e. transmission bit, power and subcarrier, and the improvement of system performance.The research work in this paper is implemented through theoretical analysis and computer simulations. Firstly, the characteristics of mobile channel are introduced, and the emphasis is placed on the analysis of frequency selective channel. Then the basic principle of wideband multicarrier wireless transmission is discussed in detail. This part develops a good theoretical infrastructure for the following researches.Secondly, the resource allocation problem for single-user multicarrier system is discussed. The ideal resource allocation scheme is described. Meanwhile, considering the real-time and low-complexity requirements of practical system, we introduced several sub-optimal schemes with low computational complexity whose advantages and disadvantages are analyzed and computer simulations are done. Simulation results shows that compared to the traditional fixed resource allocation, the adaptive resource allocation improve the system performance greatly.Finally, the resource allocation problem for multi-user multicarrier system is discussed. After the introduction of joint allocation scheme, we decouple the subcarrier allocation and other resource (bit and power) allocation processes to decrease the algorithm complexity, that is, the subcarrier allocation is performed first, followed with the bit and power allocation. Actually, the subcarrier allocation process can be considered as a kind of multiplexing access of multi users. Under the background of multimedia communication, this paper proposes two subcarrier allocation schemes considering the different proportionality of data rates among users: the subset-based and Hungarian method-based subcarrier allocation scheme. Simulation results show that the two proposed schemes can realize the proportional fairness among users efficiently and effectively, which guarantees the fairness among different users.