Researches On Coalitional Game Based Interference Management In Heterogeneous Cellular Network

With the increase of intelligent terminals and mobile broadband data busi-ness, wireless communication service with higher data rate, full coverage, lower latency and lower power cost is necessary. Due to the bottleneck of the traditional macrocell network in terms of network construction, coverage and system capacity enhancement, a-cademia and industry unanimously propose to design more efficient network deployment strategies and communications technologies to meet the demand of wireless communi-cation. Fortunately, the heterogeneous cellular network with its high system capacity, in-depth coverage, flexible deployment and low installation and maintenance costs has stood out. The basic idea of the heterogeneous cellular network is to deploy one tier or multiple-tier low power small sites underlaying existing communication infrastructure. Moreover, all types of sites can organically integrated with each other to provide high quality service for mobile users, and it has become a research focus of the current and future wireless cellular network. However, the deployment of heterogeneous cellular net-works is accompanied with numerous technical challenges in the aspect of interference management. In heterogeneous cellular networks, the interference is randomized, com-plex and serious. The reason is that the small sites are deployed randomly by users and in an ultra-dense manner in hotspots, reusing all available frequency. Therefore, the network planning methods as well as the interference management technologies which are used to macrocell are no longer applicable to heterogeneous cellular networks. It is necessary to do research on more effective interference management methods to mitigate and control the interference in heterogeneous cellular network.Based on the theoretical methods such as probability theory, stochastic process and coalitional game theory, this dissertation has done some research on the interference man-agement for heterogeneous cellular networks. By the depth analysis of the characteristics of both the heterogeneous cellular network and the behaviors of the nodes, intra-tier and inter-tier interference management solutions are proposed to improve the overall system performance from the perspective of coalition formation. The main contributions of the dissertation are listed as follows:1) Game theory is the theoretical tool for analyzing the interactions between in-dependent rational players. This dissertation studies the differences between non- cooperative games and cooperative games. Based on the analysis of the competitive be-havior and the cooperative behavior of heterogeneous cellular network users, it is claimed that it is of great importance to design interference management schemes by using coali-tional game theory. Besides, the basic concepts of coalitional game theory are summa-rized.2) To solve the intra-tier interference problem in the indoor environment, a FAPs’ cooperation approach is proposed for the uplink transmissions in a femtocell network. To obtain the sum-rate capacity, FAPs’cooperation problem is modeled as a coalitional game in characteristic form with transferable utility by using coalitional game theory. Moreover, the optimal coalition structure and its stability are derived. To get the rate allocation of the sum-rate capacity, three rate allocation strategies are compared, and the simulation results illustrate the influence of different rate allocation strategies on the stability of the coalition structure.3) A new cooperative interference management approach which allows the FUEs to merge into cooperative groups, i.e., coalitions, for the uplink transmissions in a femtocell network is proposed to reduce the random intra-tier interference. Taking into account the power cost for cooperation, it is claimed that all the FUEs are impossible to merge togeth-er, and the proposed cooperative problem is formulated as a coalitional game in partition form. To get the solution, a novel distributed coalition formation algorithm, i.e., RSSI-based coalition formation algorithm, is proposed. And furthermore, the convergence and the stability of the final solution obtained by using the proposed algorithm are analyzed.4) Considering both the achievable data rate and the power cost, a novel inter-tier in-terference management scheme based on FUE and MUE cooperation by using D2D tech-nology is proposed in multiple macrocell heterogeneous cellular networks. It is proved that the proposed scheme can be modeled as a coalitional game in partition form with non-transferable utility. In order to maximize the individual payoff of each user, a new "Pairwise Merge" distributed coalition formation algorithm is proposed. Compared with the recursive core algorithm, the solution of the proposed algorithm is stable. Moreover, simulation results show that the proposed algorithm can guarantee the individual payoff of each user with lower computational complexity.