Power aware scalable multicast routing protocol for MANETs

Multicasting is an effective way to provide group communication. In mobile ad hoc networks (MANETs), multicasting can support a wide variety of applications that are characterized by a close degree of collaboration. Since MANETs exhibit severe resource constraints such as battery power, limited bandwidth, dynamic network topology and lack of centralized administration, multicasting in MANETs become complex. The existing multicast routing protocols concentrate more on quality of service parameters like end‐to‐end delay, jitter, bandwidth and power. They do not stress on the scalability factor of the multicast. In this paper, we address the problem of multicast scalability and propose an efficient scalable multicast routing protocol called ‘Power Aware Scalable Multicast Routing Protocol (PASMRP)’ for MANETs. PASMRP uses the concept of class of service with three priority levels and local re‐routing to provide scalability. The protocol also ensures fair utilization of the resources among the nodes through re‐routing and hence the lifetime of the network is increased. The protocol has been simulated and the results show that PASMRP has better scalability and enhanced lifetime than the existing multicast routing protocols. Copyright © 2005 John Wiley & Sons, Ltd.     

Moralism: mobility prediction with link stability based multicast routing protocol in MANETs

In recent research, link stability is getting tremendous attention in mobile adhoc networks (MANETs), because of several impediments that occur in a reliable and robust network. Link stability metric is used to improve network performance in terms of end-to-end delay, data success delivery ratio (DSDR) and available route time (ART). Energy consumption, bandwidth and communication delay of major concern in ad hoc networks. A high mobility of MANET nodes reduces the reliability of network communication. In a dynamic networks, high mobility of the nodes makes it very difficult to predict the dynamic routing topology and hence cause route/link failures. Multicast in MANETs is an emerging trend that effectively improves the performance while lowering the energy consumption and bandwidth usage. Multicast routing protocol transmits a packet to multicast a group at a given time instant to achieve a better utilization of resources. In this paper, node mobility is considered to map better their movement in the network. So, the links with long active duration time can be identified as a stable link for route construction. Variation in signal strength is used to identify whether the direction of the node is towards or away from estimating node. We consider signal strength as QoS metric to calculate link stability for route construction. Efforts are made to identify the link with highly probable longer lifetime as the best suitable link between two consecutive nodes. We predict the movement time of nodes that define the route path to the node destination. Exata/cyber simulator is used for network simulation. The simulation results of the proposed routing protocol are compared with on-demand multicast routing protocol and E-ODMRP, which works on minimum hop count path. Analysis of our simulation results has shown improvement of various routing performance metrics such as DSDR, ART, routing overhead and packet drop ratio.     

新的多速率多播拥塞控制方案

提出了一种新的基于数据包束探测(packet-bunch probe)和TCP吞吐量公式的多速率多播拥塞控制方案PTMCC(packet-bunch probe and TCP-formula based multicast congestion control)。这种接收端驱动的拥塞控制,采用数据包束来探测网络的可用带宽,利用TCP吞吐量公式得到TCP友好速率,并采用了新的速率调节算法。仿真实验表明,PTMCC在收敛性、灵敏性以及TCP友好性上具有较好的性能。     

WSN中基于身份的高效多播认证协议

分析了无线传感器网络中已有多播认证协议的不足,给出了基于PKC的WSN安全协议研究进展,并提出一种基于身份的高效多播认证协议.该协议具有消息恢复功能,可有效缩短签名长度,减少协议的通信和计算开销,克服公钥密码体制开销大的缺点.在随机预言模型下证明了协议在适应性选择消息攻击和身份攻击下是存在性不可伪造的.最后,基于MICA2DOT无线传感器网络节点对协议的能量消耗进行了定量分析,结果表明,本协议的性能优于HESS、Zhang和BLS等协议,能更好地适用于资源受限的WSN环境.     

Overlay multicast for MANETs using dynamic virtual mesh

Overlay multicast protocol builds a virtual mesh spanning all member nodes of a multicast group. It employs standard unicast routing and forwarding to fulfill multicast functionality. The advantages of this approach are robustness and low overhead. However, efficiency is an issue since the generated multicast trees are normally not optimized in terms of total link cost and data delivery delay. In this paper, we propose an efficient overlay multicast protocol to tackle this problem in MANET environment. The virtual topology gradually adapts to the changes in underlying network topology in a fully distributed manner. To save control overhead, the participating nodes only keep a fisheye view of the dynamic mesh. The multicast tree is progressively adjusted according to the latest local topology information. Simulations are conducted to evaluate the tree quality. The results show that our approach solves the efficiency problem effectively. This research was supported in part by the National Science Foundation under the grants CCR-0296070 and ANI-0296034. The preliminary results of this work is presented in “Efficient Overlay Multicast in Mobile Ad Hoc Networks,” Proc. IEEE WCNC 2003. Chao Gui is a Technical Research Staff at Kiyon Inc (www.kiyon.com). His research interests include wireless networking and mobile computing. His current efforts are on industrial implementation of wireless mesh networks and embedded systems. Dr. Gui has received Ph.D. in Computer Science from University of California at Davis in 2005. Prasant Mohapatra is currently a Professor in the Department of Computer Science at the University of California, Davis. He has also held various positions at Iowa State University, Michigan State University, Intel Corporation, Panasonic Technologies, Institute of Infocomm Research, Singapore, and the National ICT, Australia. Dr. Mohapatra received his Ph.D. in Computer Engineering from the Pennsylvania State University in 1993. He was/is on the editorial boards of the IEEE Transactions on computers, ACM/Springer WINET, and Ad hoc Networks Journal. He has served on numerous technical program committees for international conferences, and served on several panels. He was the Program Vice-Chair of INFOCOM 2004, and the Program Co-Chair of the First IEEE International Conference on Sensor and Ad Hoc Communications and Networks, (SECON-2004). Dr. Mohapatra’s research interests are in the areas of wireless networks, sensor networks, Internet protocols and QoS.     

移动AdHoc网络的单信道媒体接入协议

AdHoc网络中的信道接入是一个比较复杂的问题,单信道接入协议是目前AdHoc网络中应用最广泛的,本文介绍了AdHoc网络中MAC协议需要解决的主要问题和设计要求,并列举分析了几种典型的基于CSMA/CA的由原端发起的单信道接入协议。最后总结了在MAC协议中常用的退避算法:二进制退避算法(BEB)和倍数增线性减算法(MILD),指出其中存在的问题。     

利用network coding的多速率多播最大吞吐量问题研究

本文研究了利用network coding的多速率多播最大吞吐量问题.与以往研究重点集中在单速率多播中的network coding研究工作不同,本文考虑了链路的异构性问题并采用多速率多播来解决该问题.首先文中形式化地描述了多速率多播最大可得吞吐量问题,并证明了在分层独立和层速率固定条件下,利用network coding的多速率多播最大吞吐量问题是NP-hard类问题,同时给出了最大吞吐量的上界.此外本文同时也研究了分层相关和层速率可变情况下的最大吞吐量问题.     

On the optimal multi-rate throughput for multicast with network coding

This paper investigates the maximal achievable multi-rate throughput problem of a multicast session at the presence of network coding. Deviating from previous works which focus on single-rate network coding, our work takes the heterogeneity of sinks into account and provides multiple data layers to address the problem. Firstly formulated is the maximal achievable throughput problem with the assumption that the data layers are independent and layer rates are static. It is proved that the problem in this case is, unfortunately, Non-deterministic Polynomial-time （NP）-hard. In addition, our formulation is extended to the problems with dependent layers and dynamic layers. Furthermore, the approximation algorithm which satisfies certain fair- ness is proposed.     

Exploring mesh and tree-based multicast. Routing protocols for MANETs

Recently, it became apparent that group-oriented services are one of the primary application classes targeted by MANETs. As a result, several MANET-specific multicast routing protocols have been proposed. Although these protocols perform well under specific mobility scenarios, traffic loads, and network conditions, no single protocol has been shown to be optimal in all scenarios. The goal of this paper is to characterize the performance of multicast protocols over a wide range of MANET scenarios. To this end, we evaluate the performance of mesh and tree-based multicast routing schemes relative to flooding and recommend protocols most suitable for specific MANET scenarios. Based on the analysis and simulation results, we also propose two variations of flooding, scoped flooding and hyper flooding, as a means to reduce overhead and increase reliability, respectively. Another contribution of the paper is a simulation-based comparative study of the proposed flooding variations against plain flooding, mesh, and tree-based MANET routing. In our simulations, in addition to "synthetic" scenarios, we also used more realistic MANET settings, such as conferencing and emergency response.     

Energy efficient secured routing protocol for MANETs

The design of routing protocol with energy efficiency and security is a challenging task. To overcome this challenge, we propose energy-efficient secured routing protocol. The objective of our work is to provide a secured routing protocol, which is energy efficient. To provide security for both link and message without relying on the third party, we provide security to the protocol by choosing a secure link for routing using Secure Optimized Link State Routing Protocol. Each node chooses multipoint relay nodes amongst the set of one-hop neighbors, so as to reach all two-hop neighbors. The access control entity authorizes nodes announcing the node identification to the network. In addition, the access control entity signs a public key Ki, a private key ki, and the certificate Ci required by an authorized node to obtain the group key. Each node maintains a route table with power status as one of its entry. After selecting the link, on requirement of a new route, we check nodes’ power status in its routing table and then accordingly arise a route. Then, we perform group key distribution using the generated keys using a small number of messages which helps reducing energy consumption. The group key can be altered periodically to avoid nonauthorized nodes and to avoid the use of the same group key in more than some amount of data. Then, we provide communication privacy for both message sender and message recipient using Secure Source Anonymous Message Authentication Scheme. Thereby, the message sender or the sending node generates a source anonymous message authentication for message for releasing each message based on the MES scheme. Hence, our approach will provide message content authenticity without relying on any trusted third parties.     

A secure multicast protocol for the internet's multicast backbone

In this paper we propose a secure and efficient multicast protocol where the key management is distributed to local groups. The proposed protocol takes advantage of MBone topology to maintain scalability and efficiency at the same time. Copyright © 2001 John Wiley & Sons, Ltd.     

The polarized gossip protocol for path discovery in MANETs

In this paper we present a novel probabilistic protocol for path discovery in Mobile Ad Hoc Networks (MANETs). The protocol implements what we call a polarized gossiping algorithm. While in the classical gossip algorithm each node forwards a message with the same probability, our proposal is characterized by a variable gossiping probability, which is high enough only for sustaining the spreading process towards the destination. The gossiping probability of a node is determined by the difference between its proximity to the destination and the proximity to the destination of the node from which the message was received. Differently from other proposals no external location service support, e.g., via GPS, is required. Rather, the proximity is estimated from the “inside” of the network using periodic beacons for determining the time elapsed since a node met the destination and the dwell time of a node with the destination. These information are then exploited by nodes to modulate their gossiping probability. The paper reports a mathematical model for the analysis of the algorithm along with an extensive simulation study of its implementation, which shows the suitability of the proposed solution.     

多速率自适应技术在Ir协议中的应用研究

在RRU设备的组网过程中,由于新设备的引入,需要兼容多种速率的光接口,多速率自适应技术不需要人为对RRU设备的光接口速率进行干预.以TI公司的TLK6002为例,研究了RRU设备光接口多种速率自适应的难点,给出了进行速率自适应的流程图和方法.使用本方法的RRU设备,自动进行光接口速率的调整,能够大大降低网络建设中的难度...     

An Efficient and Scalable Routing for MANETs

Recently, Distributed-Hash-Table (DHT)-based routing protocols have been proposed for large scale mobile ad hoc networks (MANETs). The motive behind using DHT is to avoid/reduce network wide flooding in MANETs in route discovery phase leading to achieve more scalable network. The challenge of deploying DHT at network layer for routing purpose in MANETs is to achieve more matching between logical and physical networks. The paper describes that existing DHT-based routing protocols for MANETs lack this feature. The paper presents a new DHT based scheme [called an efficient and scalable routing for MANETs (ESR)] which reduces the ill-matching between logical and physical networks. This is achieved be distributing the logical identifier (LID) space of DHT structure among the nodes such that the physical neighbors have consecutive LID space portions, i.e. all physical neighbors of a node are also the logical neighbors of the node. Therefore the logical ID space portion of a node may be non-contiguous. Based on this logical structure, a node builds up binary-search-tree (BST) using both logical ID space portion of itself and its neighbors. This BST at the node is traversed to find the next hop for a query/message. Through simulation, the paper shows the proposed approach (ESR) performs better than the existing one in term of routing overhead, average end-to-end delay, path-stretch values and false-negative ratio.     

面向应用的车载自组织网络跨层多信道MAC协议

提出了一种面向应用的车载网络跨层多信道MAC协议。对来自应用层不同类型的消息进行实时统计,预测出最优控制信道周期,确保控制信道上安全消息的及时、可靠传输,同时采用预约机制实现消息在服务信道上的无竞争传输,提高服务信道的吞吐量。本协议适合饱和与非饱和的一般VANET环境,具有较低的计算复杂度,扩展性较好。与现存的其他协议相比较,仿真结果证实了所提协议的优越性。     

MANET中基于AODV的跨层多度量路由协议

针对无线自组网按需平面距离向量路由协议(AODV)路由度量的单一化而引起的节点能耗枯竭,形成的网络区域化以及路径拥塞问题,提出一种多度量路径选择机制的路由协议――M-AODV。以AODV路由协议为基础,在路由发现阶段,根据设定的能量阈值和接收信号强度阈值选择能量较高和信号强度较强的节点作为路由节点;在路径选择阶段,首先根据物理层的接收信号强度、拥塞度和跳数计算每段链路稳定值,其次将每段路径稳定值进行累加得到整条路径的稳定值,最后选择稳定值最大的路径作为最优路径。使用NS2.35仿真软件仿真,结果表明：改进后的协议与AODV相比在端到端延时缩短了近30%,在数据包传输率、吞吐量和节点存活率方面优于AODV和I-AODV-SE路由算法。     

Relay-volunteered multi-rate cooperative MAC protocol for IEEE 802.11 WLANs

In IEEE 802.11, the rate of a station (STA) is dynamically determined by link adaptation. Low-rate STAs tend to hog more channel time than high-rate STAs due to fair characteristics of carrier sense multiple access/collision avoidance, leading to overall throughput degradation. It can be improved by limiting the transmission opportunities of low-rate STAs by backoff parameters. This, however, may cause unfair transmission opportunities to low-rate STAs. In an attempt to increase overall throughput by volunteer high-rate relay STAs while maintaining fairness, we propose a new cooperative medium access control (MAC) protocol, relay-volunteered multi-rate cooperative MAC (RM-CMAC) based on ready to send/clear to send in multi-rate IEEE 802.11. In the RM-CMAC protocol, we show that the effect of hogging channel time by low-rate STAs can be remedied by controlling the initial backoff window size of low-rate STAs and the reduced transmission opportunity of low-rate STAs can be compensated by the help of volunteer high-rate relay STAs. We analyze the performance of RM-CMAC, i.e., throughput and MAC delay, by a multi-rate embedded Markov chain model. We demonstrate that our analysis is accurate and the RM-CMAC protocol enhances the network throughput and MAC delay while maintaining the fairness of low-rate STAs.     

A cross-layer framework for multi-layer-video multicast with QoS requirements in multirate wireless networks

We propose a cross-layer framework for efficient multi-layer-video multicast with rate adaptation and quality-of-service (QoS) requirements in multirate wireless networks. We employ time division multiple access at the physical layer to transmit different video layers' data. The multicast sender then dynamically regulates the transmission rate and time-slot allocation based on the channel state information (CSI) and loss QoS requirements imposed by upper protocol layers. Under our proposed cross-layer framework, we first design a rate adaptation algorithm to fulfill the diverse loss QoS requirements for all video layers while achieving high multicast throughput. We then develop a time-slot allocation scheme which synchronizes data transmission across different video layers. Also conducted are simulation results to validate and evaluate our designed adaptive multicasting schemes under the proposed cross-layer framework.     

Improved multicast routing in MANETs using link stability and route stability

The growing popularity of multimedia applications and services needs to support several quality of service metrics such as high throughput, low energy, and jitter, which is a challenging task in mobile ad hoc networks. Because of limited bandwidth, energy constraints, dynamic topology, transmission errors, and fluctuating link stability, the links between adjacent nodes are often not reliable and may break because of node mobility. Link breakage initiates the process of rerouting either at the sender node (the node at which the link breaks) or at the source node. In either case, it leads to packet loss, delivery delays, and increased control overheads. Hence, to attain a minimum quality of service, routing protocols must address the dynamic network topology. Uncertain and varying movement of nodes necessitates stability of the links between such nodes. The objective of this paper is to propose 2 protocols, the first based on link stability and the other based on route stability. Link stability identifies a stable link from the available links to the next hop and determines a stable end‐to‐end route. The probability of successful transmission of periodic packets is used as a link stability metric to assess the stable path. Acknowledgment ‐free packets are used to check connectivity in the network. Increased probability of successful transmission implies that the selected link is sustained for longer duration and can deliver packets more reliably or, as a consequence, results in a stable link to deliver a better data rate. With a stable link, there is a reduced possibility of retransmissions, reduced end‐to‐end delay, reduced control overheads, and enhanced data delivery ratio. Selection of the most stable route for data transmission improves the performance. Experimental results from simulations performed on EXata/Cyber v2.0 simulator reveal that our proposed protocols are an improvement over the existing protocols in terms of packet delivery ratio, average end‐to‐end delay, and average route lifetime, even without route optimization with the minor increase in control packets. A case study of the application of proposed protocols is also presented.