Research On Resource Allocation Of Cognitive Radio

With the rapid development of wireless communication services, the radio spectrum as a non renewable resources become increasingly scarce. Because of realization of reutilization of frequency spectrum, cognitive radio is considered to be the effective technique to solve the problem of shortage of spectrum. Due to the reasonably allocates subcarrier and power among users to improve spectrum utilization, resource allocation become a key research topic in cognitive radio. This article focus on research on resource allocation for cognitive radio system based on the shared transmission model of hybrid overlay and underlay, the specific work as follows:Firstly, in view of some existing algorithms cannot effectively use the primary user can bear interference limit, proposed an power allocation algorithm for maximizing rate of utilization of available power. The algorithm in the primary user interference threshold maximize interference of cognitive users generated to the primary user, so that each cognitive user can share more effective power, increasing the available power utilization, and improving the cognitive users sum-rate. The simulation results show that the algorithm can effectively improve the cognitive users sum-rate.Secondly, aiming at multi-user hybrid business in cognitive wireless network model, proposing a subcarrier allocation algorithm based on hybrid priority. The algorithm in time(RT) the user prior to the non timely(NRT) user subcarrier to meet its demand for Qos, and the RT and NRT users to give priority to the use of the overlay mode of the subcarriers, and then use the underlay mode of the subcarrier. The algorithm to allocate resources according to business type reasonable, making the different service Qos needs are satisfied. The simulation results show that the algorithm can satisfy each cognitive user’s Qos requirements.Finally, according to the interference characteristics of FBMC subcarrier that only a pairs of adjacent subcarrier are influenced by pre-subcarrier, an improved ladder power allocation algorithm is proposed. In the proposed algorithm, FBMC technology is applied to the hybrid overlay and underlay shared cognitive wireless network mode for the first time; several subcarriers of distance of the primary user band edge are allocated power based on ladder distribution, and farther subcarriers are allocated equal power, improving fairness of allocating the power to each subcarrier, thus improving the cognitive user sum-rate. The simulation results show that the algorithm is better than the traditional ladder power allocation algorithm.