Study On Queuing Scheduling Mechanism For Cognitive Cooperative Networks With Energy Harvesting

With the rapid development of wireless communication technology,wireless terminals and multimedia services are increasingly diversified,the data transmission rate,reliability of communication and the communication service quality are also put forward higher requirements,the problems of the shortage of spectrum resource and its low utilization rate become more prominent.Moreover,the energy consumption in the application field of wireless communication is quite huge,and its proportion in the industry has been very high.For energy and environment,it is urgent to solve the problem of high energy consumption of communication.Therefore,breaking up the barriers to the shortage of spectrum and energy resources has become the driving force to promote the development of modern communications.Cognitive radio(CR)has attracted many scholars as an effective scheme to improve the utilization of spectrum resources.It is an intelligent communication technology that has high learning ability and adaptive ability.It can use the dynamic spectrum access(DSA)and spectrum sharing(SS)technology to improve the utilization of limited spectrum.Aiming at the problem of low efficiency and high energy consumption,the scholars proposed energy harvesting(EH)technology,that is,the receiver can collect wasted natural energy to supply the required energy utilization system.This technology alleviates the contradiction between the developing wireless communication and the increasingly scarce energy,and the purpose of green communication is realized.The cognitive radio network which combines the energy harvesting has effectively solved the two difficult problems that restrict the development of modern communication.Cooperative technology can effectively improve the reliability of communication of inter user in the system,enhance the capacity of the system and extend the coverage of communication system.The cooperative technology is introduced into the cognitive network based on energy harvesting.More performance gains can be obtained by using the appropriate cooperative strategy and scheduling mechanism.Therefore,the performance optimization of the cognitive cooperative network based on energy harvesting has become one of the research problems.In this paper,the queue scheduling mechanism of cognitive cooperative network is deeply studied.The main work is as follows:(1)The queue scheduling of cognitive cooperative network based on energy harvesting is studied.In the system,secondary user(SU)can decode the primary data that is not decoded by the destination node,and transmit the these primary data packets after accessing the idle spectrum.In addition,the SU is equipped with an energy collection receiver to receive the radio frequency(RF)energy generated by transmission of primary data.Constrained by the stability of the data queue,a reasonable queue scheduling algorithm is proposed to control the scheduling probability in real time to achieve sub-system optimization.(2)In order to make the queuing scheduling algorithm closer to the actual communication system,this paper studies the effect of imperfect spectrum sensing on queuing scheduling of cognitive cooperative networks with energy harvesting.The maximum tolerable queue delay of PU is constrained,which is stricter compared with the queue stability condition.Based on this constraint,the SU throughput and the average queue delay are optimized simultaneously.According to the characteristics of the optimization problem,the one-dimensional linear search method is decomposed into a series of linear problems,and the computational complexity of optimization problem solving is simplified.The influence of the uncertainty of spectrum sensing on the performance of the system is verified by simulation,and the performance of the cooperative and non-cooperative systems is compared.