Energy Saving Strategy Research In Cognitive Radio Networks

With the development of the wireless communication, the number of users and communication traffic are increasing rapidly, on the other hand wireless spectrum becomes more and more crowded. However, according to surveys the utilization of wireless spectrum is not very high. In order to improve the spectrum utilization, cognitive radio technology emerged. On the other hand, in the past5years, the amount of data has increased10times, and in cognitive radio networks, spectrum sensing is used to detect the spectrum holes, so the power consumption also increases. Face of the above problems, reducing the energy consumption of wireless networks is particularly important. The research of the energy saving in cognitive radio networks, not only can reduce carbon dioxide emissions, but also can reduce the telecom operators operating costs.In this paer, the energy saving strategies in the ideal scenario of cognitive cooperative spectrum sensing is first studied. And the corresponding cooperative spectrum sensing detection probability, false alarm probability, and the modeling of cooperative spectrum sensing in cognitive radio networks under the unit power obtained throughput are given out. Joint optimization of spectrum sensing and transmission strategies related parameters, the use of convex optimization theory proved system efficiency and the functional relationship between the variables. This paper first approximation to simplify the use of the original optimization problem, and made a loop iteration method and the dichotomy to maximize the energy efficiency of the system.Basis on the ideal cognitive scenario, the paper further studied the energy saving policies in the non-ideal scenario. Cognitive modeling of non-ideal scenario interference model, ensure that the total transmit power constraints and each primary user under the premise of normal communication maximize system efficiency. Since the original problem is a mixed integer optimization problem, we propose a two-step resource allocation strategies. The first sub-carrier allocation and planning using fractional and sub-gradient method allocate the transmission power, to maximize the energy efficiency of cognitive radio networks.The results showed that the spectrum detected in an ideal scenario, the collaboration can improve detection accuracy, and improve the energy efficiency and reduce energy consumption network. Consider the scenario of spectrum sensing errors, the system detects the spectrum obtained EER ideal scenario about5%lower, but it can better protect the primary user’s normal communication. On the other hand, this paper proposed the energy-saving strategies to maximize the network efficiency, and the energy efficiency achieved by it is higher than that obtained by the schemes of maximizing the capacity of the cognitive radio networks.