基于mSCTP异构网络垂直切换性能优化方案

基于mSCTP,通过分析影响垂直切换性能的两个问题,即切换到新路径上的慢启动现象导致的吞吐量骤降,以及由于原无线信号的迅速衰减使得SACK丢失导致的多余重传,引入一种垂直切换性能优化的改良方案mSCTP-IPVHO。通过仿真表明,mSCTP-IPVHO能在一定程度上优化异构网络垂直切换性能。     

Optimization of Handover Parameters for Traffic Sharing in GERAN

Cellular network traffic is unevenly distributed both in time and space, which greatly complicates network dimensioning. As a result, some cells in the network are permanently congested, while others are underutilized. In a previous paper, the authors showed that this problem can be effectively solved in GSM/EDGE Radio Access Networks (GERAN) by modifying handover boundaries. However, several drawbacks prevent operators from fully exploiting the potential of this technique. This paper investigates the limitations of current traffic-sharing approaches with tight frequency reuses in GERAN. To deal with such limitations, an algorithm is proposed to jointly optimize handover margins and signal-level constraints based on network statistics for traffic sharing in GERAN. A complementary algorithm is proposed to adjust cell (re)selection offsets to minimize the number of handovers. Simulation results show that the proposed method achieves a significant reduction in call blocking without excessive call quality impairment or increase of network signaling load when compared to the current approaches. More traffic can thus be handled without the need for any hardware upgrades, providing a cost-effective means to increase network capacity.

异构无线网络的快速垂直切换改进方案

异构无线网络间的切换延迟是影响无线网络融合实时应用的重要问题。采用IEEE802.21标准所定义的媒介独立切换功能（MIHF）,基于FVHMIPv6提出了一种新的快速垂直切换方案,并详细描述了该方案的执行过程。最后的切换分析表明,结合了MIHF的FVHMIPv6方案可以优化和加强原先FVHMIPv6的性能。     

移动IPv6移动性能的改进

主要问题是移动IPv6协议中移动主机移动性能的改进。通过对现有方案的研究和分析，提出了一种新的多层次移动IPv6方案。新方案中采用了新的方法计算主机的移动速度以便移动主机选择合适的MAP，同时还提出了新的缓存机制来减少转交过程中数据包的丢失。还利用了NS2对新方案进行了模拟仿真。新方案可以适应移动主机的快速移动，并能够减少绑定更新报文和数据包的丢失。     

蜂窝网中基于位置预测的切换算法

为了满足未来移动网络蜂窝小、切换频繁、支持规模用户和多媒体应用的需求,对位置预测与越区切换进行深入分析,提出了基于位置预测的越区切换方案HDLP(Handover Decision based on Location Prediction),其基本思想是:(1)从移动用户的大量历史移动轨迹数据中挖掘频繁轨迹;(2)根据挖掘出的频繁轨迹集合生成运动规则;(3)将运动规则运用于判决蜂窝移动通信的越区切换中。对所提算法进行仿真的结果表明,与传统的切换方案相比较,本算法减少了不必要的越区切换次数,降低了错误切换率,提高了切换的准确率,进而在一定程度上降低了通信代价,提高了通信系统的容量以及QoS。     

一种新路由切换策略的研究

Based on some basic handover rules, a new routing handover strategy is proposed and the performance is analyzed. The handover strategy is under considerations of handover, delay and load. Its performance is compared with other handover strategies The simulation results show that the new strategy performs better with less delay, lower handover frequency and can equipoise the network flux.     

MIPv6协议的切换算法的发展及其安全性研究

移动节点切换安全是移动IPv6网络今后研究中最基本的问题之一.切换安全时于保障移动IPv6网络的完整性、可用性,推动其实际应用具有重要意义.本文在全面地阐述了切换算法的发展历程的基础上,对切换过程的网络威胁、安全性需求及现状进行了总结,然后分别对当前的代表性切换算法提供的保护机制进行安全性分析,指出了这些算法相对于安全性需求存在的不足,最后进一步分析和总结了研究现状中存在的问题、需要研究的内容和切换安全性研究的发展趋势.     

基于灰色预测的链路即将中断触发算法

及时有效的链路即将中断(LGD)触发机制对网络切换的性能有重要的影响。首先引入IEEE 802.21介质独立切换(MIH)标准,利用MIH提供的信息服务估计出网络切换所需时间,然后提出了一种基于灰色预测的LGD触发机制,通过估计的切换时间建立灰色预测模型,预测出终端的接收信号强度,动态确定触发时刻。并且为了降低预测开销,提出了基于信号衰减检测的灰色预测建模方法。仿真结果表明,算法实现了LGD及时有效地触发,而且可以减少不必要的预测开销,避免了终端资源的浪费。     

A novel re-authentication scheme based on tickets in wireless local area networks

Fast re-authentication schemes during handover of a mobile station are essential to seamless services for real-time multimedia applications in wireless local area networks. Although much research has been done to reduce re-authentication latency, the schemes developed so far either suffer from heavy burden problems or degrade the security level. In this paper, a novel ticket-based approach is proposed for re-authentication during handover. The mobile station receives handover tickets from the authentication server as a proof of authorization, and it presents the corresponding ticket when associating with a new access point. Our scheme reduces re-authentication delay to the delay of 2-way handshake between a mobile station and an access point. Furthermore, this scheme imposes less burden over the entities compared with other proactive key pre-distribution schemes, while satisfying 802.11i security requirements.     

LTE—A系统中基于多目标的CoMP切换算法研究

协作多点传输（CoMP）作为LTE—A系统中的一项关键技术,能消除或降低相邻小区间干扰,提升边缘用户的传输性能。由于这一新技术的弓l入,传统切换算法已经不能适应CoMP技术的切换要求,由此根据CoMP中联合处理（JP）技术的特点提出了一种新的切换算法。首先分析CoMP技术的实现原理并阐述了切换的概念,然后对传统A3切换算法和新的切换算法进行了研究,最后对两种算法的性能进行了仿真。结果表明：与传统A3切换算法相比,新的切换算法能提高系统吞吐量和减少系统切换总次数。