Resource Allocation in Coded Cooperative Relay for Multi-channel Cognitive Radio Networks

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By providing unlicensed (also known as secondary or cognitive) users the capability to share the wireless channel with licensed (also known as primary) users in an opportunistic manner, as long as the interference introduced to primary users is kept below a predefined threshold, cognitive radio technology has emerged as a promising solution to improve the utilization of wireless spectrum resources. Cognitive radio networks are envisioned to provide high bandwidth to mobile users via heterogeneous wireless architectures and dynamic spectrum access techniques, while improving connectivity and self-adaptability of channel environment. This technology is, however, limited in coverage and network connectivity due to emissions restrictions imposed on secondary cognitive radio terminals. On the other hand, cooperative communication technology has been studied extensively for traditional wireless networks and shown to be a powerful approach to combat the detrimental effects of wireless channels and improve system performance by exploiting the spatial diversity over dispersed nodes. It allows multiple wireless nodes to share their resources (bandwidth and power) and assist each other in information delivery, with the objective of achieving better overall performance, i.e. greater reliability and efficiency. Moreover, coded cooperation, that integrates channel coding with cooperative communication, provides significant performance gains for a variety of channel conditions while maintaining the same information rate, transmit power and bandwidth as a comparable non-cooperative system. The aim of this research program is to provide a novel practical framework for the fundamental problem of resource allocation (relay selection, power, rate, and channel) in energy-efficient relay-based cognitive radio networks. This will integrate coded cooperative communication technology into the design of the communications protocols of cognitive radio systems to improve the performance of both spectrum sensing and secondary transmissions, and to reduce the required transmission power of each cognitive user with quality-of-service guarantee. The anticipated outcomes will provide some scientific insights on issues related to the efficient development and operation of reliable cognitive radio networks with high data rates, and thus strongly impact the future and evolution of wireless communications, by contributing to the large-scale deployment of the cognitive radio technology. These outcomes will be of significant importance to the research community, the wireless industry, government labs, the practitioners in the field, and spectrum regulatory agencies.