A Domain-Based Routing Protocol for SSM Source Mobility in Mobile IPv6 Networks

In Mobile IP, the signaling traffic overhead will be too high since the new Care-of-Address (CoA) of the mobile node (MN) is registered all the way with the home agent (HA) whenever the MN has moved into a new foreign network. To complement Mobile IP in better handling local movement, several IP micro protocols have been proposed. These protocols introduce a hierarchical mobility management scheme, which divides the mobility into micro mobility and macro mobility according to whether the host's movement is intra-domain or inter-domain. Thus, the requirements on performance and flexibility are achieved, especially for frequently moving hosts. This paper introduces a routing protocol for multicast source mobility on the basis of the hierarchical mobile management scheme, which provides a unified global architecture for both uni- and multicast routing in mobile networks. The implementation of multicast services adopts an improved SSM (Source Specific Multicast) model, which combines the advantages of the existing protocols in scalability and mobility transparency. Simulation results show that the proposed protocol has better performance than the existing routing protocols for SSM source mobility.     

Multicast support for mobile hosts using Mobile IP: Design issues and proposed architecture

In this paper, we consider the problem of providing multicast to mobile hosts using Mobile IP for network routing support. Providing multicast in an internetwork with mobile hosts is made difficult because many multicast protocols are inefficient when faced with frequent membership or location changes. This basic difficulty can be handled in a number of ways, but three main problems emerge with most solutions. The tunnel convergence problem, the duplication problem, and the scoping problem are identified in this paper and a set of solutions are proposed. The paper describes an architecture to support IP multicast for mobile hosts using Mobile IP. The basic unicast routing capability of Mobile IP is used to serve as the foundation for the design of a multicast service facility for mobile hosts. We believe that our scheme is transparent to higher layers, simple, flexible, robust, scalable, and, to the extent possible, independent of the underlying multicast routing facility. For example, our scheme could interoperate with DVMRP, MOSPF, CBT, or PIM in the current Internet. Where differences exist between the current version of IP (IPv4) and the next generation protocol (IPv6), these differences and any further optimizations are discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

一种基于MobiCast的移动IP组播方案

本文提出一种改进的MobiCast方案来实现移动IP组播通信,主要解决MobiCast方案中进行区域间切换时组播数据包丢失问题。与MobiCast方案相比,在区域外地代理(DomainForeignAgent,DFA)处引入一种缓存的机制。当移动节点发生区域间切换时,移动节点的旧区域外地代理采用隧道技术,将移动节点的信息和缓存的组播数据包发送给移动节点的新区域外地代理处,减少移动节点进行区域间切换时丢失的组播数据包。     

Bandwidth-satisfied multicast trees in large-scale ad-hoc networks

The purpose of this paper is to construct bandwidth-satisfied multicast trees for QoS applications in large-scale ad-hoc networks (MANETs). Recent routing protocols and multicast protocols in large-scale MANETs adopt two-tier infrastructures to avoid the inefficiency of the flooding. Hosts with a maximal number of neighbors are often chosen as backbone hosts (BHs) to forward packets. Most likely, these BHs will be traffic concentrations/bottlenecks of the network. In addition, since host mobility is not taken into consideration in BH selection, these two-tier schemes will suffer from more lost packets if highly mobile hosts are selected as BHs. In this paper, a new multicast protocol is proposed for partitioning large-scale MANET into two-tier infrastructures. In the proposed two-tier multicast protocol, hosts with fewer hops and longer remaining connection time to the other hosts will be selected as BHs. The objective is not only to obtain short and stable multicast routes, but also to construct a stable two-tier infrastructure with fewer lost packets. Further, previous MANET quality-of-service (QoS) routing/multicasting protocols determined bandwidth-satisfied routes for QoS applications. Some are implemented as a probing scheme, but the scheme is inefficient due to high overhead and slow response. On the contrary, the others are implemented by taking advantage of routing and link information to reduce the inefficiency. However, the latter scheme suffers from two bandwidth-violation problems. In this paper, a novel algorithm is proposed to avoid the two problems, and it is integrated with the proposed two-tier multicast protocol to construct bandwidth-satisfied multicast trees for QoS applications in large-scale MANETs. The proposed algorithm aims to achieve better network performance by minimizing the number of forwarders in a tree.     

Flooding for Reliable Multicast in Multi-Hop Ad Hoc Networks

Ad hoc networks are gaining popularity as a result of advances in smaller, more versatile and powerful mobile computing devices. The distinguishing feature of these networks is the universal mobility of all hosts. This requires re-engineering of basic network services including reliable multicast communication. This paper considers the special case of highly mobile fast-moving ad hoc networks and argues that, for such networks, traditional multicast approaches are not appropriate. Flooding is suggested as a possible alternative for reliable multicast and simulation results are used to illustrate its effects. The experimental results also demonstrate a rather interesting outcome that even flooding is insufficient for reliable multicast in ad hoc networks when mobility is very high. Some alternative, more persistent variations of flooding are sketched out.     

Efficient Resource Allocation for Wireless Multicast

In this paper, we propose a bandwidth-efficient multicast mechanism for heterogeneous wireless networks. We reduce the bandwidth cost of an Internet protocol (IP) multicast tree by adaptively selecting the cell and the wireless technology for each mobile host to join the multicast group. Our mechanism enables more mobile hosts to cluster together and leads to the use of fewer cells to save the scarce wireless bandwidth. Besides, the paths in the multicast tree connecting to the selected cells share more common links to save the wireline bandwidth. Our mechanism supports the dynamic group membership and offers mobility of group members. Moreover, our mechanism requires no modification to the current IP multicast routing protocols. We formulate the selection of the cell and the wireless technology for each mobile host in the heterogeneous wireless networks as an optimization problem. We use integer linear programming to model the problem and show that the problem is NP-hard. To solve the problem, we propose a distributed algorithm based on Lagrangean relaxation and a network protocol based on the algorithm. The simulation results show that our mechanism can effectively save the wireless and wireline bandwidth as compared to the traditional IP multicast.     

Integrated services packet networks with mobile hosts: Architecture and performance

This paper considers the support of real-time services to mobile users in an Integrated Services Packet Network. In the currently existing architectures, the service guarantees provided to the mobile hosts are mobility dependent, i.e., mobile hosts experience wide variation in the quality of service and often service disruption when hosts move from one location to another. The network performance degrades significantly when mobile hosts are provided with mobility independent service guarantees. In this paper we have proposed a service model for mobile hosts that can support adaptive applications which can withstand service degradation and disruption, as well as applications which require mobility independent service guarantees. We describe an admission control scheme for implementing this service model and evaluate its performance by simulation experiments. Simulation results show that, if sufficient degree of multiplexing of the mobility dependent and independent services are allowed, the network does not suffer any significant performance degradation and in particular our admission control scheme achieves high utilization of network resources.     

Wireless Ad Hoc Multicast Routing with Mobility Prediction

An ad hoc wireless network is an infrastructureless network composed of mobile hosts. The primary concerns in ad hoc networks are bandwidth limitations and unpredictable topology changes. Thus, efficient utilization of routing packets and immediate recovery of route breaks are critical in routing and multicasting protocols. A multicast scheme, On-Demand Multicast Routing Protocol (ODMRP), has been recently proposed for mobile ad hoc networks. ODMRP is a reactive (on-demand) protocol that delivers packets to destination(s) on a mesh topology using scoped flooding of data. We can apply a number of enhancements to improve the performance of ODMRP. In this paper, we propose a mobility prediction scheme to help select stable routes and to perform rerouting in anticipation of topology changes. We also introduce techniques to improve transmission reliability and eliminate route acquisition latency. The impact of our improvements is evaluated via simulation.     

SIP Multicast-Based Mobile Quality-of-Service Support over Heterogeneous IP Multimedia Subsystems

The Universal Mobile Telecommunications System (UMTS) all-IP network supports IP multimedia services through the IP Multimedia Subsystem (IMS). This paper proposes a mobile Quality-of-Service (QoS) framework for heterogeneous IMS interworking. To reduce the handoff disruption time, this framework supports the IMS mobility based on the concept of Session Initiation Protocol (SIP) multicast. In our approach, the mobility of a User Equipment (UE) is modeled as a transition in the multicast group membership. With the concept of dynamic shifting of the multicast group's members, the flow of actual data packets can be switched to the new route as quickly as possible. To overcome mobility impact on service guarantees, UEs need to make QoS resource reservations in advance at neighboring IMS networks, where they may visit during the lifetime of the ongoing sessions. These locations become the leaves of the multicast tree in our approach. To obtain more efficient use of the scarce wireless bandwidth, our approach allows UEs to temporarily exploit the inactive bandwidths reserved by other UEs in the current IMS/access network. Analytic and simulation models are developed to investigate our resource reservation scheme. The results indicate that our scheme yields comparable performance to that of the previously proposed channel assignment schemes.     

The Performance Analysis of the Multicast Extension Support for Proxy MIPv6

Mobile multicast is based on the traditional multicast protocols and the mobility support protocols to provide the multicast services for the mobile subscribers. Several mobile multicast methods were proposed in the past few years, but most of them are based on Mobile IPv6 and its variants which require the mobile node to support the mobility function. Recently, Proxy Mobile IPv6 (PMIPv6) was proposed to provide the mobility support for the mobile node with or without mobility function, and the previous studies have shown that PMIPv6 can improve the performance in term of the handover performance and protocol cost. However, PMIPv6 mainly concerns on the mobility support for unicast routing and little considers the multicast routing. In this paper, we propose two multicast methods called the MAG (Mobile Access Gateway)-based method and LMA (Local Mobility Anchor)-based method based on the different multicast delivery transmission path to extend PMIPv6, and analyze their performance under the different scenarios. The analytical results show that the LMA-based method is suitable for the higher speed, bigger domain size, and larger network topology scenarios, whereas the MAG-based method is suitable for the lower speed, smaller domain size and smaller network topology scenarios.     

基于代价函数的动态分布式解析映射机制

针对身份与位置的动态解析映射问题,依据终端的移动模式和通信特征,提出了一种基于代价函数的动态分布式移动解析映射机制。该机制将移动终端的通信状态划分为移动更新、均衡传输和解析查询3种通信模式,以最小化解析映射代价为目标,分别提出了基于分布式多播、一致性散列协同和主动式域内共享的解析映射方法,设计了对应的注册更新、解析查询和数据路由解析优化策略。仿真结果表明,该机制实现了移动过程中解析映射代价的最小化,具有较小的解析时延,对网络结构的动态变化具有良好的适应性。     

360 m 20 Gbit/s的W波段无线通信系统

为了满足未来空间高速通信的迫切需求,进行了W波段(75~110 GHz)无线高速通信的研究。通信系统中采用光子上变频技术产生传输速率为20 Gbit/s的W波段QPSK信号,解决了电子器件带宽受限的瓶颈问题。在接收机端采用模拟下变频和先进数字信号处理技术,实现了无线传输360 m距离后信号的离线解调。最终系统的误码率小于硬判决前向纠错(FEC)门限3.8×10?3。     

An efficient multicast protocol for PCS networks

In a Personal Communication Services (PCS) network, mobile hosts communicate with other mobile hosts through base stations on a wired (static) network. The mobile hosts connect to different base stations through wireless links and the base stations to which mobile hosts are connected change depending on the current location of the mobile hosts. In this environment, the problem of efficiently delivering a multicast message from one mobile host to a group of other mobile hosts becomes challenging. In this paper, we present a multicast protocol that delivers multicast messages from a mobile host to a group of other mobile hosts without flooding the wired network. The multicast protocol is built on top of a user location strategy that should follow one of the three models of user location described in the paper. The basic multicast protocol proposed guarantees exactlyonce message delivery to all mobile hosts in the multicast group and also ensures that multicast messages are delivered in FIFO order from the point of view of the base station that originates the multicast message (referred to as BSFIFO). More importantly, an extension of the basic protocol is provided that, unlike earlier work, delivers multicast messages in FIFO order from the point of view of the mobile host that initiates the multicast message (referred to as MHFIFO). The modifications to be made to the multicast protocol to accommodate each of the three models of user location is also described.     

Mobility of sources and listeners: real-time support of multicast services

In today??s Internet there is an increasing demand for group-based multimedia sessions, such as video/audio conferencing, IPTV, push media. Moreover, there is an increasing trend for mobile communications, with large network dynamic events, which require fast resilience to keep, as much as possible, sessions alive over time. In this sense, the bandwidth-constrained data transport scheme of IP multicast allows traffic optimization throughout the network. However, current IP multicast support over mobile communications is not efficient, mainly due to the IP addressing scheme and mobility. If multicast sources mobility is taken into account, then the performance of IP multicast is significantly degraded, due to the requirement for constantly changing the overall multicast tree. In this paper we propose a new solution for agent-based multicast in both sources and listeners mobile environments, called MUlticast TEleport (MUTE). MUTE considers the existence of anchor points in the network that provide proxy features, assuming the view of multicast data source inside the network, and establishing independence between listeners and sources movements. Moreover, we propose MUTE extension to efficiently support time-sensitive sessions, which consists in integrating IEEE 802.21 and QoS-aware abstracted transport approach, to allow media independent transport with fast resilience support. The evaluation of MUTE was carried out in NS-2, and the results show that it is able to provide both multicast sources and listeners mobility with decreased disruption time and increased network performance in heterogeneous systems.     

IP multicast for mobile hosts

We present alternative designs for efficiently supporting multicast for mobile hosts on the Internet. Methods for separately supporting multicasting and mobility along with their possible interactions are briefly described, and then various solutions to the combined problem are explored. We examine three different multicast delivery mechanisms and compare them based on their efficiency and impact on host protocol software. We describe proposals for integrating multicasting and mobility in the Internet architecture. We first present IP extensions for host mobility and other extensions for multicasting. We then examine local multicasting mechanisms, focusing on a group membership protocol that is optimized for wireless point-to-point links. Next, we examine the problems of sending and receiving multicast datagrams in a wide area network. For multicast reception, we describe three alternative proposals and compare them by examining both their applicability and their performance, as well as possible tradeoffs among the two     

依赖源汇聚点的组播协议

域间组播一直是大范围内部署组播时需要考虑的主要因素。依赖源汇聚点组播是一种基于Chord查找协议的简单有效的域间组播方案，方案中接收者的指定路由器（DR）使用Chord协议获得源RP地址，并加入源RP树。依赖源汇聚点的组播方案是一种域同ASM解决方案；能提供很好的容错性和可扩展性；支持主机移动组播，但不会造成三角路由问题。     

An Efficient Multicast Routing Protocol in Wireless Mobile Networks

Providing multicast service to mobile hosts in wireless mobile networking environments is difficult due to frequent changes of mobile host location and group membership. If a conventional multicast routing protocol is used in wireless mobile networks, several problems may be experienced since existing multicast routing protocols assume static hosts when they construct the multicast delivery tree. To overcome the problems, several multicast routing protocols for mobile hosts have been proposed. Although the protocols solve several problems inherent in multicast routing proposals for static hosts, they still have problems such as non-optimal delivery path, datagram duplication, overheads resulting from frequent reconstruction of a multicast tree, etc. In this paper, we summarize these problems of multicast routing protocols and propose an efficient multicast routing protocol based on IEFT mobile IP in wireless mobile networks. The proposed protocol introduces a multicast agent, where a mobile host receives a tunneled multicast datagram from a multicast agent located in a network close to it or directly from the multicast router in the current network. While receiving a tunneled multicast datagram from a remote multicast agent, the local multicast agent may start multicast join process, which makes the multicast delivery route optimal. The proposed protocol reduces data delivery path length and decreases the amount of duplicate copies of multicast datagrams. We examined and compared the performance of the proposed protocol and existing protocols by simulation under various environments and we got an improved performance over the existing proposals.