【作者】 张楠；

【导师】 张英海；

【作者基本信息】 北京邮电大学 ， 微电子学与固体电子学， 2010， 硕士

【摘要】 在未来的无线通信网络的发展中,异构网络是最具有发展前途的网络体系结构,它实现多种无线接入技术的融合,将现有的和未来将要出现的多种无线接入系统有机的融合在一起,满足未来用户对各种不同类型业务的需求。接入选择算法作为异构网络无线资源管理中的关键技术,选择的结果不仅会影响用户的服务质量,还会对整个网络的资源利用以及负载均衡产生较大的影响。本文针对异构网络接入选择算法现有研究存在的问题,指出了现有接入选择算法忽略的因素,即忽略了业务的非对称性对异构网络接入选择的影响。业务的接入在上下行链路同时满足接入请求的情况下才允许新业务的接入,业务的非对称性会引起网络上下行负载率的非对称,当网络的上下行负载率具有较大差异时,会因为上下行链路中某一条链路资源不足而拒绝业务的接入,而另一条链路却存在较大的资源剩余,会造成假性拥塞现象。业务的非对称性提高了系统阻塞率,浪费了系统资源,降低了网络的吞吐量。为了解决这个问题,本文提出一种新型的异构网络接入选择算法,充分考虑业务的上下行非对称性,为业务选择合适的网络,实现网络的上下行链路间的负载均衡,避免因网络上下行负载率不对称而引起的业务阻塞的发生,从而降低业务的阻塞率,提高系统的资源利用率和网络吞吐量。最后,通过matlab设计了异构无线网络系统级仿真平台,验证了提出的算法的性能。通过与传统的基于网络间负载均衡的异构网络接入算法进行比较,新算法在阻塞率、上下行链路的平均吞吐量方面都具有较大的改善。更多还原

【Abstract】 In the future development of wireless communication networks, heterogeneous network is considered to be the most promising network architecture.It implements the integration of a variety of wireless access technologies.Existing and future wireless access systems will be integrated into a seamless organic whole which will meet the requirements of different type services of future users.Multi-radio access selection (MRAS) algorithm is a key technology in radio resource management of heterogeneous network. The result of choice will not only affect the user’s service quality, but also has a great impact on the entire network resource utilization and load balance.Existing MRAS algorithms are introduced and the problems of present algorithms are discussed in this paper,The most significant problem is that the existing MRAS ignores asymmetry of the servers which will have large impact on network selection.Call admission control (CAC) allows permission of service when both link of system satisfy the access requirements.Asymmetry of the servers will cause unbalance between the uplink load and downlink load. When there are a large differences between uplink load and downlink load, one of the links will refuse the access requirement because of the lack of resources, while the other link, there are remaining resources.The asymmetry of services will increase the blocking probability of the heterogeneous network. It is a waste of system resources and reduces the network throughput. This paper proposes a new MRAS based on DL/UL load balance which realizes the load balance between uplink and downlink by selecting an appropriate network as the targeted network for a new service.It can reduce the blocking rate, improve the system resource utilization and enlarge throughput of the heterogeneous network.In the last part, a system-level simulation platform based on the heterogeneous wireless network is designed by matlab.It evaluated the performance of the proposed algorithm.The simulation results show that the new algorithm has a large improvement in the blocking rate, DL and UL throughput compared with traditional MRAS based on load balance in heterogeneous network.更多还原