Showing papers on "Ad hoc wireless distribution service published in 1997"

Signal stability-based adaptive routing (SSA) for ad hoc mobile networks

Abstract: Ad hoc networks have no spatial hierarchy and suffer from frequent link failures which prevent mobile hosts from using traditional routing schemes. Under these conditions, mobile hosts must find routes to destinations without the use of designated routers and also must dynamically adapt the routes to the current link conditions. This article proposes a distributed adaptive routing protocol for finding and maintaining stable routes based on signal strength and location stability in an ad hoc network and presents an architecture for its implementation. Interoperability with mobile IP (Internet protocol) is discussed.

Associativity-Based Routing for Ad Hoc Mobile Networks

Abstract: This paper presents a new, simple and bandwidth-efficient distributed routing protocol to support mobile computing in a conference size ad-hoc mobile network environment. Unlike the conventional approaches such as link-state and distance-vector distributed routing algorithms, our protocol does not attempt to consistently maintain routing information in every node. In an ad-hoc mobile network where mobile hosts (MHs) are acting as routers and where routes are made inconsistent by MHs‘ movement, we employ an associativity-based routing scheme where a route is selected based on nodes having associativity states that imply periods of stability. In this manner, the routes selected are likely to be long-lived and hence there is no need to restart frequently, resulting in higher attainable throughput. Route requests are broadcast on a per need basis. The association property also allows the integration of ad-hoc routing into a BS-oriented Wireless LAN (WLAN) environment, providing the fault tolerance in times of base stations (BSs) failures. To discover shorter routes and to shorten the route recovery time when the association property is violated, the localised-query and quick-abort mechanisms are respectively incorporated into the protocol. To further increase cell capacity and lower transmission power requirements, a dynamic cell size adjustment scheme is introduced. The protocol is free from loops, deadlock and packet duplicates and has scalable memory requirements. Simulation results obtained reveal that shorter and better routes can be discovered during route re-constructions.

Routing in ad hoc networks using a spine

Abstract: We present a two-level hierarchical routing architecture for ad hoc networks. Within each lower level cluster, we describe a self-organizing, dynamic spine structure to (a) propagate topology changes, (b) compute updated routes in the background, and (c) provide backup routes in case of transient failures of the primary routes. We analyze and bound the worst case of movements between upper level clusters to show that this hierarchical architecture scales well with network size.

A system and traffic dependent adaptive routing algorithm for ad hoc networks

Abstract: 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 computational requirements.

Using Location Information to Improve Routing in Ad Hoc Networks

Abstract: In ad hoc network environments, any techniques to reduce high routing-related overhead are worth investigating. This brief note explains how to exploit location information to improve ad hoc routing. We also suggest some optimization approaches that can improve the performance of the protocol.

Issues in Supporting Quality of Service in Mobile Ad Hoc Networks

Abstract: This paper addresses issues in supporting Quality of Service (QoS)-based delivery in mobile ad hoc networks. It first describes the generic character of mobile ad hoc networks (a.k.a. mobile packet radio networks), some ways in which they differ from non-wireless multihop networks, and the impact these differences have on supporting QoS-based delivery. It then briefly gives some thoughts on supporting QoS in these systems.

Mutual Exclusion on Multihop, Mobile Wireless Networks

Abstract: The system considered in this paper is a mobile wireless network, commonly known as an ad hoc network. Mobile nodes in this dynamic topology function both as processors and routers to provide communication between nodes which are not within wireless transmission range. We present a token based mutual exclusion algorithm designed for an ad hoc distributed system. This mutual exclusion algorithm modifies a logical tree structure when link failures occur or when the token moves, thereby adapting to node mobility.

A Routing Protocol for Physically Hierarchical Ad Hoc Networks

Abstract: Several routing schemes proposed for ad hoc networks assume that all mobile hosts have the same transmission power and bandwidth constraints. However, in real world, this assumption may often not be true since there exist many types of mobile hosts with different transmission capacity and mobility rate. This paper discusses a new ad hoc network architecture, called `Physically Hiera rchical Ad Hoc Networks'' where two kinds of mobile hosts form the ad hoc network hierarchy: Super Mobile Hosts(Super-MHs) and Mini Mobile Hosts (Mini-MHs). The paper presents a protocol for routing in such a network. The protocol is based on the idea that most communication between Mini-MHs can be provided through a Super-MH playing the role of mobile base station for Mini- MHs.

A distributed multicast routing protocol for ad-hoc (flat) mobile wireless networks

Abstract: "Multicasting" refers to the transmission of the same information to several destinations. We present a loop-free, distributed multicast routing protocol for wireless networks that consist of an arbitrarily large number of nodes, each of which is mobile in an unpredictable manner. Most existing multicast protocols have been developed for non-wireless, stationary networks in which there is an abundance of bandwidth and where intended destinations initiate their connection to the multicast tree. In mobile wireless networks of the future, bandwidth may be limited if not scarce, and in addition to destination initiated connections, there will be purely source-initiated multicasts. We propose a combined multicast routing and resource reservation protocol, which is source-initiated and which uses dynamic frequency allocation to establish, and maintain, connections to desired destinations in the randomly varying topology of ad-hoc wireless networks. Power control is applied to tradeoff between routing delays and frequency reuse factor.