Research Of Resource Allocation Algorithm Based On Service Characteristic In Cognitive OFDM System

With the increase of service types of mobile communication, the mobile user’s service requirement is from voice to comprehensive services including voice, data and video stream. The current spectrum allocation policy belongs to static fixed spectrum allocation, that is to say, it divides the frequency spectrum into authorized frequency band and unauthorized frequency band. The imbalance of such spectrum allocation strategy leads to serious waste of resource and becomes the bottleneck to the further development of mobile communication. The cognitive radio technology can perceive frequency spectrum holes in the authorized spectrum intelligently and can improve the frequency spectrum resource scarcity situation. Combined cognitive radio technology and OFDM technology not only can take full advantage of OFDM technology with the user scheduling flexibility and the resource allocation dynamics and so on, but also can able to effectively use the idle resource of authorized frequency spectrum hole, and provides a good technical support platform to fully meet the increasing Qo S demand of users.Based on the resource allocation model considering service characteristics in the cognitive OFDM system, a resource allocation scheme suitable for the streaming media service is proposed. The scheme takes Artificial Fish Swarm Algorithm(AFSA) to allocate subcarriers and puts forward the Simple Power Interference(SPI) algorithm to allocate power. The target is to maximize the downlink system capacity of the system within the total power budget and do not disturb the primary user. And the simulation has been carried out to verify that the proposed scheme has superior performance.Then, based on the resource allocation algorithm suitable for the streaming media service and in order to meet different service Qo S requirement as well as improve the utilization rate of wireless resource, the service model including data, voice and streaming media services is build and resource allocation is carried out in the system. Taking the pre-power allocation using the inverses ratio to interference factor method, and on the basis of the preset power allocation, the scheme takes the subcarrier allocation for different users by the artificial fish algorithm at first, then, takes power allocation by simplified power allocation method. The simulation and analysis shows that the proposed scheme can meet different Qo S and delay requirements of users’ different services and effectively improve system capacity and reduce the algorithm complexity under the premise of not affecting PU communication and its performance is close to the optimal solution.