Research On Resource Allocation Algorithm In CoMP OFDM Systems

Currently, due to the limited radio resources, it is necessary to manage radio resource for more high-speed data transmission, steady QoS guarantee and various services. To satisfy the diverse demands on data rate from multiple services, improving the efficiency of the resource allocation has been the hotspot in wireless networks.This thesis focuses mainly on the resource allocation algorithms in wireless networks. Firstly, this thesis introduces the background of the research, and then it illustrates the fundamental knowledge of the wireless channel, OFDM channel and utility function. Secondly, the resource allocation approach is researched in single-cell scenarios of OFDM system. In general, subcarrier allocation plays a role in the resource allocation algorithms of OFDM system. These approaches are divided into two different types:"one type was to decouple the solution into an initial resource allocation step, wherein the number of subcarriers and amount of power for each user is determined; and subsequently a subcarrier assignment step, wherein each user is assigned their corresponding subcarriers. On the other hand, another type is to first determine the subcarrier allocation, followed by the power allocation". We mainly focus on two different algorithms ("FIND-ROOT" AND "LINE") of the second type. In simulation, although both of them solve the problem of rate-adaptive resource allocation, "LINE" approach performs better than the "FIND-ROOT" approach in terms of computational complexity and total capacities.Finally, the resource allocation of OFDM-CoMP networks with mixed traffic patterns is also evaluated in this thesis. In OFDM-CoMP networks, the utility based centralized joint resource allocation approach, as well as the utility based distributed joint resource allocation approach and the proportional-fair resource allocation approach are simulated. The simulation results show that two different approach based on utility can gain a better performance in throughput、sum utility、 packet drop ratio and outage ratio, compared with the proportional-fair approach. However, exploiting the average power allocation in these above algorithms leads to power wasting, so a water-filling power allocation algorithm is proposed to replace the average algorithm. This improved approach promotes throughput and sum utility effectively. In addition, a project based on water-filling power allocation is proposed for OFDM networks.