Resource Allocation for Cognitive Radio Networks with Cooperative Relaying
Date
2020
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Abstract
Resource allocation is a key issue to efficiently utilize the spectrum in wireless communication systems. A promising technology for efficient spectrum usage, cognitive radio (CR), allows the secondary users (SUs) to make use of the spectrum that has been assigned to the licensed users, also known as primary users (PUs). The spectrum can be accessed by SUs as long as the PUs are idle or the interference caused by the SUs is below some threshold. Therefore, the management of such spectrum resources needs to be carefully investigated. Allocation is a problem in resource management which aims to find a way for the SUs to access proper licensed channels based on certain criteria. Meanwhile, the geographical distribution of the system users leads to spatial reuse and primary system protection, e.g., exclusion zone approximation problem. As the number of devices significantly grows, the coordination among different devices in such networks needs to be carefully considered as well. In this dissertation, we investigate the following issues in spectrum resource allocation for cognitive radio networks (CRNs). For the exclusion zone approximation problem, theoretical analysis has been proposed in prior work to find the range of the zone. For the spectrum allocation problem, game theoretic approaches have been proposed so that the optimal channels could be allocated to the SUs. All the above approaches could be further extended to more realistic and complicated scenarios such as relay transmission. In our work, we first adopt a Gaussian random field model (GRFM) to approximate the radius of an exclusion zone to protect PUs from SU interference. This approach allows us to find the coverage of exclusion zone using limited observations of signal power and interference received by the SUs. Second, we propose a novel Stackelberg-game based framework to model the behavior of SUs and PUs in cooperative relaying, and design hybrid scheduling algorithms to solve the resource allocation problem in CRNs. Numerical results show that significant improvement in terms of CRN system capacity can be achieved under cooperative relaying. Third, we propose a hierarchical Stackelberg game/mean field game framework to coordinate the behavior of the cognitive devices and control transmit power under cooperative relaying, and develop a finite difference method for determining the optimal power control scheme in this setting.