Research On Issues Of Radio Resource Management In Heterogeneous Wireless Networks

With the rapid development of mobile communication and information technology, various emerging wireless access technologies out of the area of wireless communication are to satisfy people’s needs of work and life. Different wireless technologies are heterogeneous in terms of access technology, terminal and service, which brings challenges to the reliability, stability and expansibility of heterogeneous integrated network. Facing multi-users, multi-services, high-speed service needs and complex heterogeneous wireless environment, in order to effectively use the wireless resources in heterogeneous network, efficient dynamic management mechanism of wireless resources is highly needed to guarantee fine performance of the whole integrated system. Therefore, the research of wireless resources management mechanism is very significant.This paper researches on network selection, vertical handoff, call admission control and provider pricing for wireless resource management in heterogeneous wireless networks. In the same time, it proposes corresponding optimal schemes that are veritified to be valid through mathematics model and simulation results. Specifically, This paper main contributions can be included in the follows:In the first place, an optimal mechanismfrom two aspects is proposed on how to make a network selection in heterogeneous network, one is to optimize the determination method of decision-making factor weights, and using fuzzy Analytic Hierarchy Process (AHP) and extension theory to obtain weights is raised, by which the degree of membership of each decision-making factor could be obtained through the calculation of extension theory and the degree of variance among networks is also reflected. Then in the combination of service types obtaining service membership degree of each decision-making factor, the comprehensive weights of each decision-making factor obtained by using Fuzzy Analytic Hierarchy Process (AHP). This mechanism overcame the subjectivity of man-made scoring in AHP. The other is to propose a simple and effective optimal method taking into account of users’and service suppliers’preferences, by which the performance of function value of each candidate network under the preferences of users and service suppliers would be calculated respectively by Simple Additive Weigting(SAW) method, and corresponding weighting coefficient could be dynamically set in accordance with the actual situation of network. Then adding the performance values of each candidate network together will achieve the general performance value of each candidate network, and the one with maximum general performance value is optimal network. Simulation results show that the proposed network selecting mechanism, on the premise of taking users’ and service suppliers’ preferences into consideration, effectively balanced the load of different network and increased the use efficiency of the whole system.In the second place, an optimized idea is proposed taking handoff trigger in the process of vertical handoff of heterogeneous wireless network, target network selecting and cutover execution as an organic whole. Taking SINR as the decision factor of handoff trigger, a combined model prediction method is proposed by connecting gray prediction model and BP neural network, so as to increase the predicting accuracy of SINR and reliability of switch trigger mechanism. Then a cost function is constructed, which could select target network in line with network actual situation, requirement of QoS and users’preference. Before the execution of vertical handoff, the selected target network would be accessed several times in regular period, so as to reduce the unnecessary handoff and system signaling overhead. Simulation results show that the proposed vertical handoff mechanism is capable of increasing the system throughput, reducing the number of times of vertical handoff and lowering system dropping probability.Next, an optimal combined call admission control mechanism is proposed, in which the peak rate that users could get in different areas covered by wireless network and different service types are taken into consideration, and the joint call control mechanism is modeled into a semi-Markov decision-making model. Corresponding status spaces are established based on network capacity, and corresponding action spaces are also established in view of different service types and call types, at the same time, state transition probability of system is deduced on the basis of service model. In addition, in the light of QoS requirement and analysis of network conditions, an admission utility function based on service types is put forward to estimate theadmission utility. On the basis of guaranteeing success rate of service admission and low blocking rate, the maximum value of average admission utility will be obtained through optimal control strategy. Simulation results show that the established admission utility function is able to effectively reflect the influences of changing network conditions to admission control, satisfy the requirement of QoS, and obtain higher average admission utility and larger system throughput and guaranteeing lower blocking rate.Final, this paper proposes prcing and resource allocation scheme based on game theory in multi providers and multi users heterogeneous wireless environment. First discusses the noncooperative game producing effect on provider pricing, Nash equilibrium is considered as the solution of this game. Next, considers the pricing under the cooperative game, comparing the providers revue difference between noncooperative game and cooperative game. Final, a allocation scheme is adopted to attain maximation revue of both providers ang users based on multi-leader Stackelberg games, and designs a user revue function about uer utility, user cost and delay cost. A distributed iterative algorithm is derived to obtain optimal bandwidth allocation and pricing strategies for user and providers respectively.