Resource Allocation Based On Energy-efficient And Spectrum-efficient In Cognitive Radio

In recent years, with the rapid development of wireless communication, the demand for high speed wireless services is becoming higher. Therefore, the wireless spectrum resources become increasingly scarce, and the energy consumption is also increasing. Cognitive radio technology can well solve the problem of low utilization of spectrum. In cognitive radio networks, the secondary user is able to perceive the environment and change the working parameters, then adaptive access the spectrum.At the same time, the emergence of cooperative communication technology meets the needs of users for high speed business. It improves the capacity of the system through cooperative diversity technology. The future of wireless communication is not only to consider the problem of low utilization of spectrum resources, but also to emphasize energy efficiency of the green radio. In view of this, this paper has done research on the spectrum efficiency and energy efficiency in cognitive radio, the specific contents include:1、According to the cognitive radio network, the resource allocation of energy efficiency based on OFDM imperfect spectrum sensing is studied. In order not to waste power in error detection, by defining a rate loss function introduced a new energy efficiency model, expressions for the efficiency optimization can save valuable resources, such as battery life, the efficiency is larger than that of the traditional energy efficiency gain. In the optimization, all the sub channels are considered power constraint. There are two interference constraints for primary user:peak interference power constraint and the average interference power constraint, by comparing the two power constraint can measure the efficiency of performance. After calculation, verified the efficiency and the transmission power have a quasi concave relationship, and then proposes a resource allocation algorithm for energy efficiency optimization. The simulation results show that the new algorithm for energy efficiency is larger than the traditional method, and in certain interference power,energy efficiency based on the average interference power constraint is larger than theenergy efficiency based on peak interference power constraint.2 、 Based on the two-way relay network in cognitive radio, the resource allocation problem of spectrum efficiency based on OFDM imperfect spectrum sensing is studied. Two access mechanisms are considered: opportunistic spectrum access and shared spectrum access. Different from the traditional two-way relay resource allocation method based on cognitive, the proposed algorithms jointly optimizes the sensing time and transmit power, so as to maximize the throughput of the secondary system. In the spectrum sensing phase, the two users and relay of the secondary system are aware of the existence of the primary user, which ensures the accuracy of the results. In the stage of data transmission, in order to effectively protect the primary user, each stage are considered average interference power constraint and secondary system total power constraint, under these constraints to obtain the optimal sensing time and power allocation. Finally, the performance of the two access mechanisms is compared and the effectiveness of the proposed algorithm is verified.