We present a new distributed routing protocol for mobile, multihop, wireless networks. The protocol is one of a family of protocols which we term "link reversal" algorithms. The protocol's reaction is structured as a temporally-ordered sequence of diffusing computations; each computation consisting of a sequence of directed l i nk reversals. The protocol is highly adaptive, efficient and scalable; being best-suited for use in large, dense, mobile networks. In these networks, the protocol's reaction to link failures typically involves only a localized "single pass" of the distributed algorithm. This capability is unique among protocols which are stable in the face of network partitions, and results in the protocol's high degree of adaptivity. This desirable behavior is achieved through the novel use of a "physical or logical clock" to establish the "temporal order" of topological change events which is used to structure (or order) the algorithm's reaction to topological changes. We refer to the protocol as the Temporally-Ordered Routing Algorithm (TORA).

A mobile ad hoc network consists of wireless hosts that may move often. Movement of hosts results in a change in routes, requiring some mechanism for determining new routes. Several routing protocols have already been proposed for ad hoc networks. This paper suggests an approach to utilize location information (for instance, obtained using the global positioning system) to improve performance of routing protocols for ad hoc networks. By using location information, the proposed Location-Aided Routing (LAR) protocols limit the search for a new route to a smaller “request zone ” of the ad hoc network. This results in a significant reduction in the number of routing messages. We present two algorithms to determine the request zone, and also suggest potential optimizations to our algorithms. 1

this paper, we impose a virtual backbone structure on the ad-hoc network, in order to support unicast, multicast, and fault-tolerant routing within the ad-hoc network. This virtual backbone differs from the wired backbone of cellular networks in two key ways: (a) it may change as nodes move, and (b) it is not used primarily for routing packets or flows, but only for computing and updating routes. The primary routes for packets and flows are still computed by a shortest-paths computation; the virtual backbone can, if necessary, provide backup routes to handle interim failures. Because of the dynamic nature of the virtual backbone, our approach splits the routing problem into two levels: (a) find and update the virtual backbone, and (b) then find and update routes. The key contribution of this paper is to describe several alternatives for the first part of finding and updating the virtual backbone. In this paper, to keep the virtual backbone as small as possible, we use an approximation to the minimum connected dominating set (MCDS) of the ad-hoc network topology as the virtual backbone. The hosts in the MCDS maintain local copies of the global topology of the network, along with shortest paths between all pairs of nodes. We note that the concept of a virtual backbone is not new. Ephremides et al.

We develop an on-demand, multipath distance vector protocol for mobile ad hoc networks. Specifically, we propose multipath extensions to a well-studied single path routing protocol known as Ad hoc On-demand Distance Vector (AODV). The resulting protocol is referred to as Ad hoc Ondemand Multipath Distance Vector (AOMDV). The protocol computes multiple loop-free and link-disjoint paths. Loopfreedom is guaranteed by using a notion of "advertised hopcount." Link-disjointness of multiple paths is achieved by using a particular property of flooding. Performance comparison of AOMDV with AODV using ns-2 simulations shows that AOMDV is able to achieve a remarkable improvement in the end-to-end delay --- often more than a factor of two, and is also able to reduce routing overheads by about 20%. 1

We evaluate several routing protocols for mobile, wireless, ad hoc networks via packet level simulations. The protocol suite includes routing protocols specifically designed for ad hoc routing, as well as more traditional protocols, such as link state and distance vector, used for dynamic networks. Performance is evaluated with respect to fraction of packets delivered, end-to-end delay and routing load for a given traffic and mobility model. It is observed that the new generation of on-demand routing protocols use much lower routing load. However, the traditional link state and distance vector protocols provide, in general, better packet delivery and delay performance. 1. Introduction A mobile, ad hoc network [4] is an autonomous system of mobile hosts connected by wireless links. There is no static infrastructure such as base stations. If two hosts are not within radio range, all message communication between them must pass through one or more intermediate hosts that double as router...

An ad hoc network consists of a number of mobile hosts who communicate with each other over a wireless channel without any centralized control. The basic problem is to obtain a distributed routing scheme so that under the network connectivity assumption any mobile host can transmit/receive data from any other host in the network. In this paper we propose a new routing algorithm for ad hoc networks. The proposed algorithm uses a more appropriate distance measure given by the expected delay along a path, instead of the number of hops used in most of the existing algorithms. This metric allows the algorithm to adapt to changes not only in the topology of the network, but also in the traffic intensity. The algorithm uses a novel technique for estimating the path delays without requiring the links to be bidirectional or the clocks at the nodes in the network to be synchronized. The proposed algorithm is able to perform both reliable and good routing with low communication overhead and compu...

this paper are: (a) how to build and maintain the spine, (b) what network topology information to collect in the spine, and (c) how to compute routes once the information is aggregated in the spine nodes. This infrastructure is specifically built to address the dynamics of the network topology, scarcity of the shared resources, and the nature of applications that may typically run in such adhoc networking environments. We address the following goals in this paper:

In this paper we evaluate several routing protocols for mobile, wireless, ad hoc networks via packet level simulations. The ad hoc networks are multi-hop wireless networks with dynamically changing network connectivity owing to mobility. In the protocol suite includes several routing protocols specifically designed for ad hoc routing, as well as more traditional protocols, such as link state and distance vector, used for dynamic networks. Performance is evaluated with respect to fraction of packets delivered, end-to-end delay and routing load for a given traffic and mobility model. Both small (30 nodes) and medium sized (60 nodes) networks are used. It is observed that the new generation of on-demand routing protocols use much lower routing load, especially with small number of peer-to-peer conversations. However, the traditional link state and distance vector protocols provide, in general, better packet delivery and end-to-end delay performance. 1 Introduction A mobile, ad hoc networ...

This work proposes a self-organizing, dynamic infrastructure called a spine for efficient routing in ad hoc networks. We present a scalable framework for routing that encompasses a range of knowledge at each spine node, and identify the trade-offs involved for routing at different points in this range. Our routing algorithm requires only partial topology information at each spine node, consisting of the spine structure, dependents of each spine node, propagation of long-lived links, and snooped routing information from ongoing flows. Through worst-case theoretical bounds and simulation of typical scenarios, we show that the spinebased routing with only partial topology information provides good routes at low overhead. 1. Introduction An ad hoc network is a multihop wireless network in which mobile hosts communicateover a shared, scarce wireless channel. Ad hoc networks lack a wired backbone to maintain routes as hosts move or turn off or on. Instead, the hosts in ad hoc network must c...

A crucial aspect of effective networking on the battlefield is choosing the correct networking architecture. Multi-hop wireless networks provide the best model for tactical networking because of their ability to self-organize and rapidly adapt to change. We focus on a multi-hop wireless network model that is highly dynamic and that consists of mobile base stations and mobile hosts. In this model, there are two key requirements for enabling an effective networking infrastructure for the battlefield: the support of highly mobile nodes and the scalability to a large number of nodes. In this paper, we present some of the systemlevel challenges encountered in highly dynamic multi-hop wireless networks. In particular, we address the topology model, the location model, and the routing model in light of the aforementioned challenges. INTRODUCTION Wireless networking technology will play a key role in future battlefield communications. The choice of the network architecture model strongly imp...