Research On The Dynamic Spectrum Management In Wireless Networks With Restless Bandits Formulation

Wireless spectrum is an essential and precious resource in wireless communications. However, with the rapid development of information communication technologies and related applications, radio spectrum has almost been used up. On the other hand, the utilization of some spectrum, such as television broadcasting system, is as low as 15% to 85%. The main reason is that the current spectrum allocation is based on the long-term and fixed policy. To solve the problem, cognitive radio(CR) has been proposed, allowing cognitive equipment to use the spectrum bands, which are authorized to the primary users but not in use without introducing interference to the primary users. Cognitive radio is considered a hot research topic in wireless communications, attracting lots of attention on its key technologies on spectrum sensing, spectrum decision, dynamic spectrum allocation, spectrum auction, and network architecture.In this paper, the dynamic spectrum management schemes with different scenarios are proposed. The spectrum allocation problem in small-cell cognitive radio networks is firstly studied. In this small cells and cognitive radio coexisting network, taking into account the case that free available spectrum bands from primary users are limit and cannot satisfy the demands from cognitive users(secondary users), an optimal secondary users scheduling mechanism scheme has been proposed, considering the important factors in small-cell designing, such as throughput, network interference and base station power. The dynamic spectrum subband management problem is formulated as a restless bandit system, whose indexibility feature reduces the optimization problem to simply selecting the subbands with the smallest indices. Then the proposed scheme is extended by introducing the concept of interference efficiency and establishing the multi-objective function as a combination of energy consumption efficiency and interference efficiency. This scheme has low computational complexity and distributed and dynamic characteristics.Besides, this thesis studies spectrum management problem in cyber-physical system(CPS). Having attention to the application layer quality of service and wireless link security, a novel dynamic spectrum management scheme has been proposed to minimize the system cost of cyber-physical surveillance system for transportation(CPSST). We adopt quality-of-service(Qo S)-centric design to optimize the Application Layer QoS with the minimization of video distortion. The method to make the usage of spectrum safer is considered in the proposed scheme, in which the concepts of security level and security cost are introduced to describe the probability of attacking. The video distortion and the chance of being attacked or peeped in the transmission subband are minimized to reduce the total system cost, which could improve system performance significantly.