一种基于业务切换的垂直切换判决算法

在下一代异构无线网络环境中,为满足在异构无线网络架构下采用不同切换方式的垂直切换请求,我们提出一种基于业务切换的垂直切换判决算法,并设计了一种基于业务切换的代价函数。通过数学分析和在UMTS,WLAN融合的网络环境下对该方案的切换失败率的仿真分析,证明了该方案在支持终端的移动性、保障用户业务请求满意度以及缓解网络负载压力上相比传统基于代价函数的垂直切换判决算法更具优势。     

一种基于异构网络的自适应垂直切换算法

提出一种基于WSN与WLAN异构网络环境下无缝移动通信的垂直切换算法。该算法针对日益普及的传感器网络自身特点与室内应急通信应用的特殊性,提出网络选取优先级参数。针对传感器网络在应急通信等特殊场合的应用．制定了专门的切换判决策略。实验分析表明,该算法可以一定程度地提高通信网络对现场场景变化的适应程度,满足室内环境下异构网络通信的需求。     

一种新的无线异构网络的自适应垂直切换算法

针对当前无线异构网络融合技术中的垂直切换机制,提出了一种以平均接收信号强度为评价指标,并由此指标判断可能的运动趋势的自适应垂直切换算法。仿真结果表明:相比于传统的固定门限的平均接收信号强度垂直切换算法,提出的方法能较好地预测并提前触发该发生的切换,改善切换性能。     

面向终端个性化服务的模糊垂直切换算法

在异构无线网络中,针对终端不同类型的应用在服务质量(QoS)需求上的差异,该文提出一种面向终端个性化服务的模糊垂直切换算法。该算法从以下两个方面提高切换性能：首先在网络发现阶段,通过预测候选网络在切换时刻的负载状态,对候选网络进行筛选;然后在切换判决阶段,根据每类应用对QoS参数的不同需求范围设计不同的隶属度函数。仿真结果表明,该算法能有效降低切换阻塞率,提高系统吞吐量,并能根据终端的应用类型合理地选择切换网络,满足了终端的个性化服务需求。     

垂直切换中的网络选择算法比较

随着移动通信技术的不断发展,通信业引入越来越多的无线通信技术标准,不同接入技术的融合已是业界公认的通信网络的发展趋势。因此。异构网络环境下的垂直切换及最优网络选择也就成为通信界的一个研究热点。现有的网络选择算法可以分为MADM（多属性决策）算法和非MADM算法两大类,文章详细阐述了两类算法的基本原理．并对两类算法的特点...     

一种基于上下文感知的垂直切换技术研究

未来网络的发展趋势是各种无线接入网络共存的异构网络环境,而垂直切换技术是融合多个异构接入网络的关键技术之一,垂直切换包括三个阶段,即系统发现、切换决策和切换执行。文中主要研究了基于上下文感知的垂直切换判决策略,并与移动垂直切换技术相结合,实现了WLAN/UMTS网络间的垂直切换,通过仿真表明该方法在吞吐量和切换时延方面都得到改善。     

一种基于身份签名的快速垂直切换认证机制研究

无缝垂直切换是异构无线网络融合的关键技术。通过分析垂直切换的执行过程,指出切换重认证所带来的长时延和分组丢失是影响切换性能的重要因素。对比分析了现有的几种重认证解决方案,指出了各种方案的利弊。最后,从统一认证的理念出发,权衡重认证的安全性和切换效率,提出了一种基于身份签名的快速重认证方案。该方案仅需移动节点保持一套认证信息,并与认证服务器交互一次就可完成双向认证,大大缩减了切换时延,提高了切换效率。     

基于mSCTP的垂直切换的研究

随着通信技术的发展,同一地区可能存在多个异构的网络,并且这些网络存在互补关系。为了充分的利用这些异构的网络,研究垂直切换技术将非常有必要。mSCTP由于其多家乡性,可以充分的支持垂直换。相比其他技术并有一定的优势。     

异构网络中基于Savitzky-Golay滤波的垂直切换算法

为了实现异构网络中的无缝链接和准确地判断网络状态,需加强确定移动台(MS)的位置信息,以及减少不利的衰落效应。本文提出了一种基于Savitzky-Golay滤波(即S-G滤波)的垂直切换算法,该算法能够使MS准确地判断网络的覆盖范围。仿真结果表明,该算法可以减少衰落效应,从而有效地减少了乒乓效应,提高了网络的性能。     

基于用户消费习惯多选权重的垂直切换算法

针对现有异构网络垂直切换算法未能充分考虑不同用户以及同一用户不同次通信对网络资源需求有所不同的问题,提出了一种基于用户消费习惯的多选权重垂直切换算法(MWVH)。算法通过计算用户近期实时业务和非实时业务消费的期望、方差以及消费频率动态改变候选网络切换利润函数中的指标权重,得到符合用户近期消费习惯的网络选择。     

A RISC architecture extended by an efficient tightly coupled reconfigurable unit

In this paper, the architecture of an embedded processor extended with a tightly-coupled coarse-grain reconfigurable functional unit (RFU) is proposed. The efficient integration of the RFU with the control unit and the datapath of the processor eliminate the communication overhead between them. To speed up execution, the RFU exploits instruction level parallelism (ILP) and spatial computation. Also, the proposed integration of the RFU efficiently exploits the pipeline structure of the processor, leading to further performance improvements. Furthermore, a development framework for the introduced architecture is presented. The framework is fully automated, hiding all reconfigurable hardware related issues from the user. The hardware model of the architecture was synthesized in a 0.13?µm process and all information regarding area and delay were estimated and presented. A set of benchmarks is used to evaluate the architecture and the development framework. Experimental results prove performance improvements in addition to potential energy reduction.     

Group vertical handoff management in heterogeneous networks

Traditional vertical handover schemes postulate that vertical handovers (VHOs) of users come on an individual basis. This enables users to know previously the decision already made by other users, and then the choice will be accordingly made. However, in case of group mobility, almost all VHO decisions of all users, in a given group (e.g., passengers on board a bus or a train equipped with smart phones or laptops), will be made at the same time. This concept is called group vertical handover (GVHO). When all VHO decisions of a large number of users are made at the same time, the system performance may degrade and network congestion may occur. In this paper, we propose two fully decentralized algorithms for network access selection, and that is based on the concept of congestion game to resolve the problem of network congestion in group mobility scenarios. Two learning algorithms, dubbed Sastry Algorithm and Q‐Learning Algorithm, are envisioned. Each one of these algorithms helps mobile users in a group to reach the nash equilibrium in a stochastic environment. The nash equilibrium represents a fair and efficient solution according to which each mobile user is connected to a single network and has no intention to change his decision to improve his throughput. This shall help resolve the problem of network congestion caused by GVHO. Simulation results validate the proposed algorithms and show their efficiency in achieving convergence, even at a slower pace. To achieve fast convergence, we also propose a heuristic method inspired from simulated annealing and incorporated in a hybrid learning algorithm to speed up convergence time and maintain efficient solutions. The simulation results also show the adaptability of our hybrid algorithm with decreasing step size‐simulated annealing (DSS‐SA) for high mobility group scenario. Copyright © 2015 John Wiley & Sons, Ltd.     

异构网络中基于终端决策的通用垂直切换算法

垂直切换是异构网络中的关键技术,目前已有的垂直切换算法大多是针对特定的网络或切换过程的某个环节,提出一种与网络类型无关的通用垂直切换算法,仿真结果表明该算法在支持多任务,有效利用能量方面比传统方法有很大的改进.     

多网络共存下基于贝叶斯的垂直切换算法

针对目前的垂直切换技术普遍不能满足多网络下的切换问题,提出了一种改进的基于贝叶斯决策的垂直切换算法。首先根据接入终端网络的信号强度、网络负载、误码率和网络阻塞率以及用户业务对网络的实际需求偏好建立多条件相关的切换概率分布,计算出先验切换概率;然后通过贝叶斯决策算法计算出后验概率来进行判决比较,从而选取最优的接入网络。仿真结果表明,该算法不仅能有效地实现不同接入技术之间的垂直切换,从而减少不必要的切换,提高了切换成功的概率,而且还能在维持各网络平均负载达到30%~40%时减轻通信热点的阻塞情况,为用户提供更优的服务质量。     

车联网中基于贝叶斯决策的垂直切换方法研究

车辆需要在车联网的异构无线网络环境下进行垂直切换,针对垂直切换技术普遍不能支持 WAVE, WiMAX和3G cellular间的垂直切换这一问题,提出了一种基于贝叶斯决策的垂直切换算法。首先,根据接入网络的信号强度、传输速率、误码率和网络阻塞率以及车辆终端的速度和运动趋势建立多条件相关的切换概率分布,计算出切换先验概率;然后通过贝叶斯决策算法计算后验概率并进行决策分类,从而选取最优网络接入。仿真实验结果表明,该算法不仅有效地实现WAVE,WiMAX和3G cellular无线接入技术之间的垂直切换,而且避免了乒乓效应,保证了网络及时更新。     

Efficient mobility management for vertical handoff between WWAN and WLAN

As we move toward next-generation all-IP wireless networks, we are facing the integration of heterogeneous networks, such as WWAN and WLAN, where vertical handoff is required. In vertical handoff between WWAN and WLAN, mobile hosts should be able to move freely across different networks while satisfying QoS requirements for a variety of applications. In order to achieve seamless handoff and maintain continuity of connection, we propose a novel mobility. management system that integrates a connection manager to detect network condition changes in a timely and accurate manner, and a virtual connectivity manager that uses an end-to-end principle to maintain a connection without additional network infrastructure support. A prototype system was built to test the effectiveness of the proposed system. Experiments show that seamless roaming between WLAN and WWAN can be achieved, and much better performance can be obtained than with the traditional scheme.     

An adaptive resource management for mobile terminals on vertical handoff

Mobile communications and wireless networks are developing at a fast pace. The increasing number of mobile subscribers and terminals are the real life evidence of the fast growing development in the area of wireless communication. Wireless communication technology is now pursuing 4G (fourth generation) and seeking a scheme to provide quality of service (QoS) to the various applications continuously even moving to another network. In this paper, we proposed a dynamic resource management architecture which considers vertical handoff situation with minimal disruption of service to the users considering seamless provision of QoS. The proposed scheme efficiently manages resources and provides stable services to the mobile terminal. The simulation results show that resource management enabled mobile terminals utilize system resources, CPU and memory, efficiently improved by 40% and 65%, respectively, rather than mobile terminals without resource tuning.     

A new handoff management system for heterogeneous wireless access networks

In heterogeneous wireless access networks, each mobile terminal may frequently need to change its base station (BS); this change is called a ‘handoff’. BSs have static parameters, which are related to their radio access technologies (RATs); however, they also contain dynamic parameters such as load and signal quality. Therefore, the problem of handoff decision includes two subproblems of RAT selection and BS selection. In this paper, first a ‘heterogeneous handoff management system’ for gathering all different required parameters is proposed. Second, a RAT Selection algorithm based on analytic hierarchy process and a BS Selection algorithm based on data envelopment analysis are designed. Finally, by means of ‘weight restriction’ technique, we develop a method for studying the impact of RAT Selection parameters on the performance of the network. Simulation results indicate that RAT Selection parameters have significant impact on the bandwidth utilization, energy consumption and the whole satisfaction of the users in heterogeneous wireless access networks.Copyright © 2012 John Wiley & Sons, Ltd.     

Sensor-based architecture for QoS provisioning and fast handoff management in WLANs

As wireless local area networks gain popularity from network access providers and customers, supporting multimedia applications becomes a crucial yet unresolved challenge. The need to maintain quality-of-service in the presence of bandwidth limitations, increasing traffic volume and user mobility entails radical rethinking in resource management design in WLANs. The unique capabilities of wireless sensor networks constitute a promising research direction to tackle these issues. In this paper, we present a new sensor-based resource management architecture for enhanced QoS provisioning and handoff management in WLANs. Through theoretical analysis and simulations, we show that the framework can maximize bandwidth utilization while satisfying applications’ QoS requirements and significantly reduce handoff latency.