A Multi-Path QoS Routing Protocol in a Wireless Mobile Ad Hoc Network

A mobile ad hoc network (MANET) is one composed of a set of mobile hosts capable of communicating with each other without the assistance of base stations. This paper considers the QoS (quality-of-service) routing problem in a MANET, which is important for many real-time multimedia applications. We propose an on-demand protocol for searching for a multi-path QoS route from a source host to a destination host in a MANET, where a multi-path is a network with a source and a sink satisfying certain bandwidth requirement. Existing works all try to find a uni-path to the destination. The basic idea is to distribute a number of tickets from the source, which can be further partitioned into subtickets to search for a satisfactory multi-path. Through simulations, we justify that the value of our multi-path protocol is in its flexibility: (i) when the network bandwidth is very limited, it can offer a higher success rate to find a satisfactory QoS route than those protocols which try to find a uni-path, and (ii) when the network bandwidth is sufficient, it can perform almost the same as those protocols which try to find a uni-path (in both routing overhead and success rate).     

Route Maintenance in a Wireless Mobile Ad Hoc Network

A mobile ad-hoc network (MANET) is formed by a cluster of mobile hosts, without the infrastructure of base stations. To deal with the dynamic changing topology of a MANET, many routing protocols have been proposed. In this paper, we consider the route maintenance problem, which includes two parts: route deterioration and route breakage. In a MANET, a route may suddenly become broken because only one host roams away. Even if a route remains connected, it may become worse due to host mobility or a better route newly being formed in the system. Existing protocols, however, will stick with a fixed route once it is discovered, until it is expired or broken. In this paper, we show how to enhance several existing protocols with route optimization and local route recovery capability. So the routing paths can be adjusted on-the-fly while they are still being used for delivering packets and can be patched in minimum wireless bandwidth and delay while route errors occur.     

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.     

Location aided probabilistic broadcast algorithm for mobile Ad-hoc network routing

On-demand routing protocols are widely used in mobile Ad-hoc network (MANET). Flooding is an important dissemination scheme in routing discovering of on-demand routing protocol. However, in high-density MANET redundancy flooding packets lead to dramatic deterioration of the performance which calls broadcast storm problem (BSP). A location-aided probabilistic broadcast (LAPB) algorithm for routing in MANET is proposed to reduce the number of routing packets produced by flooding in this paper. In order to reduce the redundancy packets, only nodes in a specific area have the probability, computed by location information and neighbor knowledge, to propagate the routing packets. Simulation results demonstrate that the LAPB algorithm can reduce the packets and discovery delay (DD) in the routing discovery phase.     

基于OPNET仿真平台的AODV协议的性能研究

AODV(Ad hoc On-demand Distance Vector Routing)路由协议是面向移动Adhoc网络的,在介绍了移动Ad hoc网络的特征、现有路由协议和AODV路由协议的发展过程之后,重点分析了AODV协议的特征、路由建立、维护过程,并基于OPNET平台仿真了AODV协议的性能(包括路由发现时间、协议效率、平均跳数、数据吞吐量),总结了目前AODV协议存在的问题及其改进的主要方法,最后对AODV协议改进的前景进行了预测。     

Integrating Mobile Ad Hoc Network to the Internet

A novel scheme is presented to integrate mobile ad hoc networks （MANETs） with the lnternet and support mobility across wireless local area networks （WLANs） and MANETs. The mobile nodes, connected as a MANET, employ the optimize d link state routing （OLSR） protocol for routing within the MANET. Mobility management across WLANs and MANETs is achieved through the hierarchical mobile IPv6 （HMIPv6） protocol. The performance is evaluated on a HMIPv6 based test-bed composed of WLANs and MANETs. The efficiency gain obtained from using HMIPv6 in such a hybrid network is investigated. The investigation result shows that the use of HMIPv6 can achieve up to 27% gain on reducing the handoff latency when a mobile roams within a domain. Concerning the reduction of the signaling load on the lnternet, the use of HMIPv6 can achieve at least a 54% gain and converges to 69%.     

A Two-Tier Heterogeneous Mobile Ad Hoc Network Architecture and Its Load-Balance Routing Problem

The mobile ad hoc network (MANET) has attracted a lot of interest recently. However, most of the existing works have assumed a stand-alone MANET. In this paper, we propose a two-tier, heterogeneous MANET architecture which can support Internet access. The low tier of the network consists of a set of mobile hosts each equipped with a IEEE 802.11 wireless LAN card. In order to connect to the Internet and handle the network partitioning problem, we propose that the high tier is comprised of a subset of the mobile hosts, called gateways, which can access to cellular/infrastructure networks. The high tier is heterogeneous in the sense that the network interfaces in the gateway hosts could be IEEE 802.11 cards, PHS handsets, or GPRS handsets characterized by different bandwidths and latencies. Observing that the gateways could become the bottlenecks of the two-tier network, we propose a set of solutions, namely boundary-moving, host-partitioning, and probabilistic solutions, to solve the load-balance routing issue. Implementation issues/concerns of these schemes are discussed. Simulation results are presented to compare these load-balance routing schemes.     

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.     

A Power-Aware Multicast Routing Protocol for Mobile Ad Hoc Networks With Mobility Prediction

A mobile ad hoc network (MANET) is a dynamically reconfigurable wireless network that does not have a fixed infrastructure. Due to the high mobility of nodes, the network topology of MANETs changes very fast, making it more difficult to find the routes that message packets use. Because mobile nodes have limited battery power, it is therefore very important to use energy in a MANET efficiently. In this paper, we propose a power-aware multicast routing protocol (PMRP) with mobility prediction for MANETs. In order to select a subset of paths that provide increased stability and reliability of routes, in routing discovery, each node receives the RREQ packet and uses the power-aware metric to get in advance the power consumption of transmitted data packets. If the node has enough remaining power to transmit data packets, it uses the global positioning system (GPS) to get the location information (i.e., position, velocity and direction) of the mobile nodes and utilizes this information to calculate the link expiration time (LET) between two connected mobile nodes. During route discovery, each destination node selects the routing path with the smallest LET and uses this smallest link expiration time as the route expiration time (RET). Each destination node collects several feasible routes and then selects the path with the longest RET value as the primary routing path. Then the source node uses these routes between the source node and each destination node to create a multicast tree. In the multicast tree, the source node will be the root node and the destination nodes will be the leaf nodes. Simulation results show that the proposed PMRP outperforms MAODV (Royer, E. M. & Perkins, C. E. (1999). In Proceedings of the ACM MOBICOM, pp. 207–218, August 1999.) and RMAODV (Baolin, S. & Layuan, L. (2005). In Proceeding of the 2005 IEEE International symposium on microwave antenna, propagation and EMC technologies for wireless communications, Vol. 2, pp. 1514–1517, August 2005.).     

An efficient MAC protocol for multi‐channel mobile ad hoc networks based on location information

This paper considers the channel assignment problem in a multi‐channel MANET environment. We propose a scheme called GRID, by which a mobile host can easily determine which channel to use based on its current location. In fact, following the GSM style, our GRID spends no communication cost to allocate channels to mobile hosts since channel assignment is purely determined by hosts' physical locations. We show that this can improve the channel reuse ratio. We then propose a multi‐channel MAC protocol, which integrates GRID. Our protocol is characterized by the following features: (i) it follows an ‘on‐demand’ style to access the medium and thus a mobile host will occupy a channel only when necessary, (ii) the number of channels required is independent of the network topology, and (iii) no form of clock synchronization is required. On the other hand, most existing protocols assign channels to a host statically even if it has no intention to transmit [IEEE/ACM Trans. Networks 1995; 3 (4):441–449; 1993; 1 (6): 668–677; IEEE J. Selected Areas Commun. 1999; 17 (8):1345–1352], require a number of channels which is a function of the maximum connectivity [IEEE/ACM Trans. Networks 1995; 3 (4):441–449; 1993; 1 (6): 668–677; Proceedings of IEEE MILCOM'97, November 1997; IEEE J. Selected Areas Commun. 1999; 17 (8):1345–1352], or necessitate a clock synchronization among all hosts in the MANET [IEEE J. Selected Areas Commun. 1999; 17 (8):1345–1352; Proceedings of IEEE INFOCOM'99, October 1999]. Through simulations, we demonstrate the advantages of our protocol. Copyright © 2005 John Wiley & Sons, Ltd.