COOCCURRENCE INTERFERENCE GRAPH (CIG) BASED HYBRID SCHEDULING SCHEME COMBINING INTERFERENCE ALIGNMENT IN DENSE FEMTOCELL NETWORKS

摘要

To satisfy the requirement of enormous wireless data services, it has been proposed to improve the network throughput by the dense deployment of femtocells with frequency reuse. However, the interference poses big challenges. The scheduling problem combing interference alignment (IA) is fundamentally different from traditional scheduling problems. On the one hand, it needs to select users to perform IA due to the feasible constraint of IA and the diversity of the interference strength. On the other hand, IA can decrease the interference in the selected IA group, while all the participant users have to be scheduled simultaneously, termed as the consistency of scheduling among participant users of the IA group. Therefore, the hybrid scheduling scheme combining IA in the dense femtocells network is studied in this paper. First, to represent the diversity of interference and the consistency of scheduling among participant users of the IA group, the combination representation model of the IA and interference named the multi-scheme cooccurrence interference graph (CIG) is constructed. Second, the available rate of each user is acquired considering the aggregate interference and asymmetry of interference, which are based on the decomposition in chordal graph and the analysis of the characteristic network topology. At last, the hybrid scheduling scheme is proposed based on the maximum weight independent set (MWIS) problem. Simulation results shows that the proposed scheme can approach the optimum solution in a small-sized network, and effectively improve the sum rate in dense networks.