异构网络中多媒体业务的联合呼叫接纳控制

提出了3G与WLAN互连的异构网络中一种多媒体业务的联合呼叫接纳控制算法,针对不同类型用户的业务特性选择合适的优先接入网络,考虑到切换用户及不同业务类型用户的优先级,分别在3G和WLAN中设置了多级的接入门限值．运用多维Markov链模型对该算法的新呼叫阻塞率和切换呼叫掉线率性能进行了理论分析．仿真结果表明,本算法在满足不同类型用户的QoS需求的同时,在新呼叫阻塞率和切换呼叫掉线率之间获得了良好的折中,提高了系统整体性能．     

基于交互测量和时延预测的无线传感网络呼叫接入控制机制

为了在无线传感网络(Wireless sensor network,WSN)中实现多媒体业务的传输,基于时延的非饱和模型,采用交互测量和时延预测的分布式接入控制机制,设计了呼叫接入控制(Call admission control,CAC)机制。最后采用NS2仿真平台对该机制的延迟性能进行了仿真分析。结果表明:该机制可以为对实时业务提供有效的延迟保证。     

3G系统自适应优先级接入控制方法

提出一种针对于第三代移动通信系统的宽带功率自适应优先级接入控制方案.通过空中接口负载因子的变化来衡量系统所承受负荷的大小,并由总接收干扰门限来判断呼叫请求的接入与否.此方案充分考虑CDMA系统的软容量特性,通过设立预留资源来达到优先级控制,自适应的调整预留资源的大小,使其始终处于最优值状态.重点研究了系统只设立两级呼叫的情况,即越区切换呼叫与新呼叫.仿真结果表明,该方案在始终满足越区呼叫阻塞率低于门限的情况下,尽可能降低新呼叫的阻塞率,使系统的信道利用率达到最大值.     

基于降级机制WCDMA系统接入控制方案

在第3代宽带码分多址系统中,为使系统在接近满负荷运转时能够满足新用户呼叫所要求的带宽,以增大新用户呼叫的接入概率,提出了基于"降级机制"的接入控制方法.即基于非实时呼叫信息码速率可调这一特性,通过降低非实时呼叫信息码速率来降低系统负载,文中在给出了设计方案的基础上还做了系统级的仿真测试,仿真结果证明加入降级机制的新方案比不加入降级机制的原方案提高了系统实时在线的用户数,降低了呼叫阻塞概率.该方案具有很好的应用前景.     

基于效用公平的低轨卫星网络呼叫准入控制算法

提出了一种新的适用于多媒体低轨卫星网络的呼叫准入控制算法。该算法利用目标小区实时切换掉线概率,结合概率门限方法和效用公平分配机制为切换呼叫预留带宽。仿真结果表明,与其他算法相比,本算法不仅提供了满意的新呼叫阻塞概率,还能够大大降低切换呼叫掉线概率,同时保证了较高的带宽利用率。     

ESWAN:无线移动网络中的一种拥塞控制方案

提出了在竞争连接环境中的一种改进的无状态无线自组织网络拥塞控制方案:ESWAN.该方案根据可利用带宽的变化,动态地调节网络源端的发送速率.分析和仿真结果表明,该方案较SWAN进一步降低了数据包的传送延迟,并提高了网络的发送速率及网络发送速率的稳定性.     

异构型无线传感器网络的生命周期

研究了一种异构型无线传感器网络的能量效率问题。该网络是具有不同初始能量的两类传感器节点以不同的数量均匀地分布在监测区域形成的,它基于簇的方式周期性采集数据传输到网关(sink)节点。本文对簇头节点和成员节点的能量消耗进行了数学建模,并且分析了网络的生命周期与检测区域参数之间的关系。通过理论分析和仿真结果得到了最大网络生命周期的最佳分簇数目以及不同层次节点的能量分配比例,并进一步导出了网络生命周期与簇头能量配置的关系。     

改进的异构无线网垂直切换算法

对异构无线网络融合中垂直切换判定算法进行研究。以典型的全球通信系统与无线局域网融合为例,引入乒乓带概念,利用移动终端当前位置、运动速度与径向运动角度等参数扩展驻留定时器算法。模拟仿真结果显示,移动终端采用该算法后即可实现预决策提前进行切换操作,避免不必要的切换,从而可保最大限度与无线局域网相连接。     

Novel routing protocol for heterogeneous wireless sensor networks

An improved LEACH for heterogeneous wireless sensor networks is proposed.Nodes are distributed in a sensing area that is divided into a number of same equilateral hexagons.Heterogeneous nodes act as the cluster heads and ordinary nodes act as those cluster sensors in all clusters.The structure of WSNs is a two-layer structure.The upper layer consists of all cluster heads and the lower layer consists of all ordinary sensors managed by their corresponding cluster heads.The cluster heads and the ordinary sensors establish their pairwise keys respectively through utilizing different methods.The arithmetic balances energy expense among all kinds of nodes,saves the node energy,and prolongs the life of wireless sensor networks.Additionally,Analysis demonstrates that the security of wireless sensor networks has been improved obviously even with some heterogeneous nodes.     

异构无线网络接入选择算法综述

移动互联网和无线通信技术的发展形成多种无线网络共存、覆盖范围重叠的异构无线网络,各种无线接入技术的差异和单一网络技术无法满足用户的全部需求使异构无线网络融合成为必然,接入选择作为异构无线网络融合的关键技术之一已成为研究热点.在简述异构无线网络基本架构和接入选择概念的基础上,对接入选择算法进行分类总结与详细对比分析,深入剖析各算法采用的方法和特点,同时对存在的问题进行总结归纳,并展望了未来的研究方向.     

An overview of intelligent selection and prediction method in heterogeneous wireless networks

Heterogeneous wireless access technologies will coexist in next generation wireless networks. These technologies form integrated networks, and these networks support multiple services with high quality level. Various access technologies allow users to select the best available access network to meet the requirements of each type of communication service. Being always best connected anytime and anywhere is a major concern in a heterogeneous wireless networks environment. Always best connected enables network selection mechanisms to keep mobile users always connected to the best network. We present an overview of the network selection and prediction problems and challenges. In addition, we discuss a comprehensive classification of related theoretic approaches, and also study the integration between these methods, finding the best solution of network selection and prediction problems. The optimal solution can fulfill the requirements of the next generation wireless networks.     

无线异构网络中终端的能耗分析模型

为了对无线异构网络中多模终端的能耗分析问题进行研究,通过考察终端的工作机理,利用半马尔科夫链描述终端的通信状态,从而得到终端的能耗分析方程. 相比已有的工作,提出的模型更全面地考虑了终端的工作状态,还考虑了终端发现wireless local area network(WLAN)的概率和业务类别等因素的影响. 分析结果表明,终端能耗随呼叫到达强度和呼叫持续时间增大而增大;终端能耗与话音业务的比例和发现WLAN的概率均成近似线性关系;使WLAN模块进入低能耗的等待状态并不会节省终端能耗.     

异构无线网络TOPSIS算法的一种改进

针对接近理想方案的序数偏好方法(TOPSIS)在异构无线网络环境的应用中容易出现逆序的问题,给出一种改进方法,即在通用移动通信系统、全球微波互联接入及两个无线局域网接入点构成的重叠覆盖区域的特定环境下,找出每个候选网络的业务服务质量(QoS)参数的取值范围,来最终确定绝对正、负理想解。由于方案个数的改变不会引起绝对理想解的改变,所以各个决策方案距绝对正、负理想解的距离不会改变。新方案集中原有方案的贴近度不变,则各方案之间的优劣顺序也不会发生变化,以此避免失序问题。在所搭建的特定环境下进行仿真实验,结果表明针对TOPSIS方法的改进是合理的。     

Downlink call admission control with power allocation and rate scheduling for IDMAbased multibeam satellite systems

Considering the advantage of interleave-division multiple-access (IDMA) technique and the technical bottlenecks in the existing satellite systems,IDMA is introduced into satellite communication network...     

性价比最大化的异构网络博弈选择策略简

A heterogeneous network selection scheme based on game theory is proposed. A non-cooperation game model is formed which is aimed to maximize the overall profits of heterogeneous networks according to the integrated quality of service and the pricing scheme of each network. The network selection scheme is proposed to maximize the result of the quality of service versus price by means of Nash Equilibrium of the game. Analysis and simulation results validate the advantage of the scheme.     

基于网格的异构无线网络负载均衡算法

针对目前软负载均衡算法中无线资源统计不具有普适性,未考虑用户业务需求与异构资源单元差异性匹配的问题,根据网格计算的思想,在异构无线网络中提出了基于网格的负载均衡算法。该算法首先将无线资源映射成不同的三维资源单元,每个三维资源单元相当于一个网格。然后将业务分成不同的子业务流(数据包),统一分给不同的网格,实现业务的分布式分流,在保证用户QoS的情况下,实现网络的负载均衡。仿真结果表明:基于网格的负载均衡算法能够较好地均衡异构网络间的负载,降低负载偏离度,提高系统吞吐率。     

一种用于无线ATM网络的呼叫允许控制方案

无线异步传输模式(ATM)网络通信系统将在宽带和多媒体个人通信得到广泛应用.提出一种用于无线ATM网络多媒体通信服务的呼叫允许控制(CAC)方案,它采用统计大量用户移动信息来估计未来业务需求和系统可用资源,并根据用户移动信息动态地调整用于潜在切换呼叫的资源预约,能有效利用无线频谱资源,增大系统容量.     

Collaborative offloading of overloaded MEC servers in ultra-dense heterogeneous networks

Mobile Edge Computing (MEC) can perform computational task offloading with the help of edge servers, and is no longer limited by the power of mobile terminals (MTs). When the edge server is overloaded, it often chooses to queue, postpone or reject the MT’s offloading request. QoS (Quality of Service) of users will deteriorate greatly due to service disruption and extended waiting, but the existing research work does not consider how the MEC-BS can relieve load pressure at this time. In this paper, we study how to enhance the computing offloading service of the MEC-BS by offloading the task of the overloaded base station to the other MEC-BS in the same collaboration space. Combining the penalty function with the two-step quasi-newton method, an optimization algorithm is proposed to minimize the joint utility function including the total delay and energy consumption of the edge computing network. Empirical factors are used to adjust the optimization deviation according to the different needs of the optimization target for time delay or energy efficiency. Simulation results show that the proposed scheme is better than two other schemes in improving the system performance and convergence speed.     

3G系统基于区分业务的接入控制

为提高无线接入控制过程的性能,针对WCDMA系统各种业务的特点,采用了能有效保障QoS的上行接入控制方案,依据具体业务的分类和QoS指标来分配网络资源,提出了一种新的接入算法-PCD(Priori-ty Code based Diffserv)算法.设计了实时和非实时业务呼叫的信令流程,并对提出的算法和现有的接入算法进行了仿真评估.结果表明,该方法有效地解决了上行接入控制问题,与随机接入算法相比具有良好的业务吞吐量和时延性能,提高实时业务的服务质量.