基于动态组播代理的移动组播协议

根据动态组播代理的移动组播算法原理,提出一种移动组播协议,采用新的快速组播切换机制,以时间量度和距离量度为依据,动态选择组播代理。仿真结果表明,该协议避免组播转发树的频繁重构,降低组播切换延迟,具有次优的组播传输路径,可以与现有网络协议相融合。     

一个有效的分布式移动IP组播路由算法

为了优化移动IP环境下组播树的代价,减少移动结点的切换时延,设计了分布式移动IP组播路由算法BNSBMR（Bone Node Set-Based Multicast Routing Algorithm）。该算法使用“骨干结点集”的思想,能大大降低组播树代价,并优化切换时延;同时使用分布式的策略来进行设计,使得算法具有良好的可扩展性,有利于在大规模移动Internet上的实现。仿真实验表明：根据该算法生成的组播树代价、时延等性能明显优于其他同类移动IP组播路由算法。     

基于动态范围的移动组播协议

提出在基于范围的移动组播协议（RBMoM）的基础上根据用户的移动特性、业务量及网络特性为每个主机动态地确定最优服务范围的算法,形成了基于动态范围的移动组播协议（DRBMoM）．该协议通过设计一个代价函数并求解使代价函数最小化的服务范围来实现减小组播分组传输时延和组播树重构频率的折衷．分析表明,代价函数值随主机的业务量和移动速度的增加而增加;最优服务范围随主机业务量的增加而减小,随主机移动速度的增加而增加．在性能对比中发现,DRBMoM的代价函数值小于RBMoM的代价函数值,表明DRBMoM的确增强了RBMoM的性能;在与同类方案的比较中,发现DRBMoM的平均切换信令代价稍高于同类方案,但其平均组播分组传输代价及最终的代价函数值均小于同类方案．     

基于区域代理选择的移动组播算法

针对移动组播接入点切换造成的组播树频繁重建问题,本文提出了基于移动频率的区域代理选择方法。整个无线网络被划分为不同的区域,在某一区域内,选择移动频率最小的节点作为该区域的组播代理,为移动网络内该区域的节点提供组播服务。实验证明,该方法有效减少了因节点移动而造成的组播树重构频率。     

基于骨干结点集的移动IP组播路由算法研究

为了优化移动IP组播生成树代价,减少移动结点切换加入时延和信息传输时延,引入了移动IP"骨干结点集"思想,设计了移动IP组播路由算法BNSBMR(bone node set-based muhicast routing algorithm),"骨干结点集"是移动IP环境下满足一定条件的IP子网接入路由器AR(access router)的集合.该算法通过"骨干结点集"降低移动IP组播生成树的代价;减少移动结点切换的加入时延;并通过路径优化降低信息传输时延.理论上证明了算法的正确性,并分析了其计算复杂度.仿真实验表明:BNSBMR算法从树代价、加入时延、传输时延3个方面提高了移动IP环境下组播业务满足QoS约束的能力.     

一种基于分区的移动IPv6组播算法

提出的基于分区的移动组播算法旨在解决移动节点远离本地网络且持续快速运动情况下的组播重构开销过大的问题,通过将网络划分成不同的区域并指定一个区域代表,降低了组播树重构频率。仿真结果表明,此算法较之FHSR算法在网络利用率及组播重构开销方面有更好的性能。     

MIP-RS与MobiCast组合的移动组播分析和实现

本文提出了MIP-RS与MobiCast组合的移动组播方案,然后通过移动组播管理的方法,将节点在域内的移动节点对外屏蔽,提高了域间组播转发树主干的稳定性,并利用快速组播机制,从而减少了切换延迟以及由此引发的分组丢失.     

移动无线Internet中的公平QoS组播路由机制

提出一种公平QoS组播路由机制,包括初始QoS组播路由树建立算法、节点加入／退出／切换机制以及树重构机制,从路由角度支持公平性的实现。仿真研究表明,该机制是可行和有效的。     

一种多QoS约束的可靠移动组播路由协议

针对复杂多变的移动组播环境,从整体上提出了一种基于优先级的报文管理机制(PDMM)。对不同类型的报文赋以不同的优先级别,提出了一种基于层次结构的自适应移动组播路由协议(AMMPH),在子网内采用隧道机制、子网间采用远程签署和隧道机制相结合的组播路由协议,保证了报文的可靠高效传输,并在寻求最短转发路径和减少组播树重构开销间取得了较好的平衡。     

一种基于移动预测的分层移动组播协议

组播通信有效地节约了网络资源,在无线移动网络环境中引入组播有着非常重要的意义。论文简要分析了现有移动组播协议,提出了一种新的基于移动预测的分层移动组播方案。仿真与分析表明,该协议组播树重构频率低,子网切换延迟小,可减少组播包的丢失,减少协议开销,优化组播包的传输路径。     

基于多播树的HMIPv6快速切换方案

为了缩短移动节点的切换延迟时间,提出基于多播树的分层移动IPv6(HMIPv6)快速切换方案。该方案采用快速切换方式建立移动锚点与移动节点之间的多播隧道,移动节点在同一个区域内始终使用相同的多播地址。仿真结果表明,与现有HMIPv6方案相比,该方案的切换时间更短、丢包率更低、性能更好。     

A weight-aware channel assignment algorithm for mobile multicast in wireless mesh networks

Wireless mesh networks (WMNs) are one of key technologies for next generation wireless networks. In this paper, we propose a heuristic channel assignment algorithm with weight awareness to support mobile multicast in WMNs. To enhance network throughput, our algorithm is based on the path forwarding weight to perform channel assignment. In addition to non-overlapping channels, partially-overlapping channels are also used in channel assignment. To fully exploit all available channels in channel assignment, we devise a new channel selection metric to consider the channel separation and the distance between nodes. In mobile multicast, the multicast tree structure cannot be fixed due to receiver (multicast member) mobility. The change of the multicast tree structure will result in channel re-assignment. The proposed algorithm is based on a critical-event driven manner to reduce the times of channel re-assignment as much as possible. Finally, we perform simulation experiments to show the effectiveness of the proposed channel assignment algorithm.     

Distributed dynamic mobile multicast

Traditional mobile multicast schemes have either high multicast tree reconfiguration cost or high packet delivery cost. The former affects service disruption time while the latter affects packet delivery delay. Although existing region-based mobile multicast schemes offer a trade-off between two costs to some extent, most of them do not determine the size of the service range, which is critical to network performance. In this paper, we propose a novel approach, called Distributed Dynamic Mobile Multicast (D²M²), to dynamically determine the optimal service range according to the mobility and service characteristics of a user. We derive an analytical model to formulate the costs of multicast tree reconfiguration and multicast packet delivery. The model is based on a Markov chain that analyzes a mobile node’s movement in a 2D mesh network. As the complexity of computing steady probability is high, we aggregate the Markov states by leveraging mobility symmetry. Simulation shows that the network performance is enhanced through D²M².     

一种基于范围的可靠移动组播算法

移动IP[1]提出了双向隧道和远程签署两种移动组播算法,各自有明显的优缺点.在以双向隧道为基础的改进算法RBMoM[4]中引入了服务范围的概念.提出移动组播算法在远程签署的基础上结合服务范围概念,寻求最优转发路径和最小组播树管理开销之间的折衷,并在节点移动时采用在移动代理间建立隧道的方式补充数据包,提高组播可靠性.对模拟结果的分析和比较显示该算法具有更好的综合性能.     

Hierarchical agent-based secure and reliable multicast in wireless mesh networks

We propose and analyze a hierarchical agent-based secure and reliable multicast (HASRM) algorithm for efficiently supporting secure and reliable mobile multicast in wireless mesh networks, with design considerations given to minimize the overall network cost incurred by reliable multicast packet delivery, mobility management, security key management, and group membership maintenance. HASRM dynamically maintains a group of multicast agents running on mesh routers for integrated mobility and multicast service management and leverages a hierarchical multicast structure for secure and reliable multicast data delivery. The regional service size of each multicast agent is a key design parameter. We show via model-based performance analysis and simulation validation that there exists an optimal regional service size that minimizes the overall communication cost and the optimal regional service size can be dynamically determined. We demonstrate that HASRM under optimal settings significantly outperforms traditional algorithms based on shortest-path multicast trees extended with user mobility, security, and reliability support. We also show that a variant of HASRM is superior to a recently proposed multicast algorithm for secure group communication in wireless mesh networks.     

移动自组网中基于移动预测和概率的能量有效组播路由算法

移动自组网中节点的使用寿命很大程度上依赖于电池能量的有效利用．通过研究移动节点能量的剩余和使用情况，提出了一种新的关于节点能量估价函数PCF（power cost function）计算方法，能够较好地反映当前节点的能耗值．并且结合PCF提出一种基于移动预测和概率构造能量有效组播树M-REMiT（an algorithm based on mobility prediction and probability for refining energy-efficient multicast tree）的分布式算法，在节点移动的情况下，利用概率优化方法减少一棵组播树的总能量消耗，延长了组播树中每个节点的使用寿命．模拟结果显示这个组播算法比以前相关的算法具有更好的性能．     

Efficient group communications in location aware mobile ad-hoc networks

The highly dynamic and uncertain character of mobile ad-hoc networks poses significant challenges for group management. Node mobility often changes the multicast tree, and therefore, frequent updates from group members are required to refresh the multicast tree at the source node. This paper presents Courier, a group communications algorithm that uses the location and velocity of roaming nodes to provide bandwidth efficient multicast between a source and its destinations (i.e., group members) in location aware mobile environments. Toward that end, Courier offers (1) a bandwidth efficient method for location updates from group members, (2) a mobility prediction model for predicting the movement of mobile group members, and (3) an overlay multicast data distribution tree (OMDDT) construction algorithm that is guided by the mobility prediction model. Comparisons of Courier to related multicast algorithms indicate an increase in data transmission success and a decrease in overall bandwidth consumption.