Resource Allocation Algorithm In Cognitive Cellular Heterogeneous Networks

The rise of smart terminal provides users with a wide variety of applications,not only drives the rapid development of communication industry,but also accelerates the innocation of communication technologies.The demand of high rate date serveces has also risen sharply.As a result,the problem of scarcity of rad spectrum resource has also become more and more serious.Cognitive radio technology is considered as the most effective method to solve the imbalance of spectrum resource allocation.CR technology can improve spectrum efficiency through spectrum sharing and effectively solve the problem of spectrum resource shortage.On the other hand,the rise of cellular heterogeneous networks techonology has spared the conventional macro network an enormous burden of coverage,and made a compensation for coverage blind zone in macrocell edge.The combination of CR and cellular heterogeneous network is considered as a promising solution for futher inprove the spectrum utilization,and cognitive cellular heterogeneous networks are closely integrated with other 5G key technologies to form a new generation of mobile communication networks that respond to the rapid changes in the information society in the future,which attract much attention.However,the large-scale deployment of cognitive cellular heterogeneous networks still faces many technical challenges.Reasonable resource allocation solution and network performance optimization play an important role in improving the overall network performance.Therefore,this paper takes the cognitive cellular heterogeneous networks as the background and starts from the problem of resource allocation in the network,the main contents of the research are as follows:1.In order to solve the problem about interference mitigation in the cognitive heterogeneous networks,this paper studied how to reduce the interference to macrocell users and improve system throughput.By analyzing the source of interference completely,the interference model with imperfect spectrum sensing was established.Based on the user topology,the optimization problem was built to maximize the downlink throughput with considering the total power constraint and interference constraint,which is include subcarriers allocation and power allocation.Then simplified the optimization problem based on the analysis of KKT conditions,and designed the resource allocation algorithm with the imperfect spectrum sensing.Simulation results and performance analyses show that the proposed algorithm has less interference to macrocell users than the algorithm with perfect spectrum sensing,and achieves better throughput performance.2.In order to solve the problem about the energy consumption due to the large-scale deployment of cognitive femtocell base stations in cognitive cellular heterogeneous networks.This paper studied the uplink resource allocation algorithm in the two-tier heterogeneous networks.A joint subchannel and power resource allocation based on double loop iteration was proposed.The optimization problem was built to maximize the cognitive system energy efficiency with considering the quality of service(QoS)requirement of real time user constraint and cross-tier interference constraint.The introduction of interference temperature makes the problem a mixed integer non-convex programming problem.The fractional form of energy efficiency was converted into an equivalent problem in subtractive form,then the optimization problem was approximated as convex optimization and solved by iterative method.The simulation results show that the algorithm can converge to the optimal energy efficiency quickly and ensure the QoS requirement of real-time users,and effectively improve energy efficiency.