Power allocation and relay selection for cooperative transmission in interference limited wireless networks

Abstract

Cooperative communication assisted by relay nodes can significantly improve the quality of wireless links due to a spatial diversity from different transmitters. Therefore, there have been extensive researches related to cooperative communication. Among plentiful studies, an effective resource allocation algorithm for cooperative transmission is important in order to adopt the cooperation to practical systems and evaluate the benefits of the cooperation. However, most of existing works on resource allocation unfortunately were not considered interference from neighboring wireless links that utilize the same frequency band. Moreover, few recent studies investigating cooperative communication in interference limited networks were not solved a joint resource allocation problem including optimal relay selection and power control. Therefore, in this thesis, we suggest an effective resource allocation algorithm for cooperative communication in interference limited wireless networks. We consider the situation where numerous cooperation pairs are uniformly distributed in a given area. Before investigating the case of multiple cooperation pairs, we concentrate on a special system model that consists of only two cooperation pairs. One is an interested cooperation pair that we allocate resources and the other is a neighboring cooperation pair that interferes to the interested cooperation pair. We can easily obtain insight of joint power allocation and relay selection from this simple situation. Then, we formulate an optimization problem of relay selection and power allocation to minimize the total power consumption while satisfying the quality of service requirement of multiple cooperation pairs. However, the optimization problem is a mixed integer non-convex problem which is one of the most difficult problems to solve. Therefore, we propose an iterative heuristic algorithm that each cooperation pair resolves the resource allocation problem of own cooperation pair using ...