Research On Distributed Radio Resource Management In Ultra Dense Networks For 5G Communication Systems

With the rapid development of mobile Internet and Internet of things, the 5th Generation mobile communication technology (5G) comes into being to meet the user’s demands for higher speed, greater data traffic and more dense network coverage.5G system requires higher network capacity and better network coverage. As an effective deployment scenario to solve seamless link of network, the Ultra Dense Networks (UDN) has been recognized as one of the key technologies for 5G communication systems. Compared to the traditional macrocell base station (BS) deployment, UDN has many advantages. Firstly, the cost is reduced because the cell deployment is performed by users. Secondly, flexible configuration is achieved to improve the energy efficiency. Thirdly, the problem of blind spots coverage is well solved and seamless connection for users is realized. However, with the intensive network deployment, UDN is also facing some technical challenges, such as the user’s access selection, inter-cell interference among small cells (SC), the user’s mobility, the effective use of radio resources and so on. These technical problems need to be solved urgently.In this thesis, the problems of radio resource management in UDN are discussed. First of all, a method based on first-price sealed-bid auction game is proposed to solve the small cell access problem for users. Another, a geometric programming based radio resource allocation is presented to solve the problem of inter-cell interference among small cells. The main contributions of this thesis are summarized as follows.1. This thesis develops a novel distributed small cell selection mechanism based on first-price sealed-bid auction game. This mechanism establishes utility functions for small cell base stations and users, and adds the reward of Service Provider (SP) for small cell base stations which participate in the auction to the small cell base utility function. It also sets the user’s access rights as auctions and users exercise the option as auctioneers. From the user’s perspective, the algorithm ensures users a better quality of service (QoS) and experience, enhances the user’s quality of experience. Simulation results demonstrate the effectiveness and superiority of the algorithm.2. The delay constraint is introduced in the optimal objective function for the proposed radio resource allocation algorithm. And the constraint value can be set according to the priorities, quality of service requirements and other conditions. This method effectively ensures the quality of service for users. The simulation results demonstrate that the delay constraint shows the effectiveness in guaranteeing the user’s quality of service.3. This thesis devises a distributed radio resource allocation scheme based on geometric programming. Unlike traditional centralized resource allocation performed by the macrocell base station, the mathematical method proposed in this thesis uses geometric programming to establish a distributed subcarrier allocation and power distribution scheme implemented by each of the small cell base station according to the capacity maximization objective function for ultra dense networks. The distributed method in practical applications not only reduces the huge signaling overhead of macro base station, but also keeps in line with the flat development direction of modern communication networks. Simulation results prove the effectiveness of the distributed resource allocation.