Adaptive resource allocation for real-time services in OFDMA based cognitive radio systems

In this paper an adaptive resource allocation algorithm in OFDMA based cognitive radio (CR) system is proposed that not only meets the quality of service (QoS) of real-time (RT) services but also increases the dynamic capacity of the system. In contrast to existing algorithms for multi-user OFDM systems which are unable to guarantee maximum sum data rate when applied to CR system in real-time, the proposed joint sub carrier and power allocation algorithm (JSPA) ensures maximum sum data rate under power constraint while improving the system capacity. We model the resource allocation problem with the goal of maximizing the overall system throughput. By judicially assigning resource in primary and secondary sources based on the types of application JSPA demonstrates that the system efficiency and throughput can be dynamically enhanced. JSPA is simulated under two types of services: constant bit rate (CBR) and variable bit rate (VBR).