Multi-cell Cognitive Radio Spectrum Allocation Algorithm

Cognitive radio (CR) is considered as a revolutionary technology which will fundamentally solve the problem of spectrum shortage. By detection the spectrum usage of licensed user, adaptively adjust the communication parameters, CR users opportunisticly choose free spectrum to communication will greatly improve spectrum efficiency.Because of the working manner and the spectrum to use are very different with the traditional wireless communication systems, the spectrum allocation of CR is facing immense challenges. How to efficiently use the dynamic changing spectrum and provide reliable communication services to CR users is an important issue need to be studied and solved.Currently the CR technology is working on two types of spectrum: One is the free spectrum in the licensed band, the other is the spectrum in unlicensed band. The CR system behavior will vary considerably in different spectrum. The former scenario includes avoiding interference to licensed users, which is the key point of existing research.Three major definitions of CR are firstly introduced in this dissertation, the current research on CR system and development of CR relevant standards is also introduced.The CR spectrum sharing model, the CR system model and the common models in CR spectrum allocation are detaily introduced in this dissertation subsequently. These models have close relationship with multi-cells spectrum allocation of CR network, which are the basis and reference of this dissertation.This dissertation studies the issue of CR network multi-cells spectrum allocation under the scenario of CR system opportunisticly access the free spectrum of licensed system. By introducing the spectrum allocation algorithms based on graph coloring model, the inadequateness of these algorithms is analyzed. The concept of spectrum quality grading is proposed to better express the characteristic of spectrum. The demand based multi-cells spectrum allocation algorithm is proposed, Graph coloring model is used in multi-cells spectrum allocation. The proposed algorithm allocates spectrum to CR cells to meet demand maximally under QoS guarantee and also improves the spectrum allocation efficiency.Through analysis of the shortcomings of graph coloring model, based on the interference temperature model this dissertation further studies the issue of CR network multi-cells power control combined spectrum allocation. Through seriously study existing interference temperature model based multi cells spectrum allocation algorithms, including two-phase resource allocation algorithm and dynamic graph based channel allocation and power control algorithm. Advanced two-phase resource allocation algorithm is proposed, which takes full advantage of the power allocated to cell to improve the utilization of CR system. In order to improve the fairness of spectrum allocation, the advanced fairness resource allocation strategy is also proposed by this dissertation, the existing algorithms are further improved to enhance allocation fairness.