Showing papers on "Geographic routing published in 2001"

Ad hoc positioning system (APS)

Abstract: Many ad hoc network protocols and applications assume the knowledge of geographic location of nodes. The absolute location of each networked node is an assumed fact by most sensor networks which can then present the sensed information on a geographical map. Finding location without the aid of GPS in each node of an ad hoc network is important in cases where GPS is either not accessible, or not practical to use due to power, form factor or line of sight conditions. Location would also enable routing in sufficiently isotropic large networks, without the use of large routing tables. We are proposing APS - a distributed, hop by hop positioning algorithm, that works as an extension of both distance vector routing and GPS positioning in order to provide approximate location for all nodes in a network where only a limited fraction of nodes have self location capability.

A survey on position-based routing in mobile ad hoc networks

Abstract: We present an overview of ad hoc routing protocols that make forwarding decisions based on the geographical position of a packet's destination. Other than the destination's position, each node need know only its own position and the position of its one-hop neighbors in order to forward packets. Since it is not necessary to maintain explicit routes, position-based routing does scale well even if the network is highly dynamic. This is a major advantage in a mobile ad hoc network where the topology may change frequently. The main prerequisite for position-based routing is that a sender can obtain the current position of the destination. Therefore, previously proposed location services are discussed in addition to position-based packet forwarding strategies. We provide a qualitative comparison of the approaches in both areas and investigate opportunities for future research.

Split multipath routing with maximally disjoint paths in ad hoc networks

Abstract: In recent years, routing has been the most focused area in ad hoc networks research On-demand routing in particular, is widely developed in bandwidth constrained mobile wireless ad hoc networks because of its effectiveness and efficiency Most proposed on-demand routing protocols however, build and rely on a single route for each data session Whenever there is a link disconnection on the active route, the routing protocol must perform a route recovery process In QoS routing for wired networks, multiple path routing is popularly used Multiple routes are however, constructed using link-state or distance vector algorithms which are not well-suited for ad hoc networks We propose an on-demand routing scheme called split multipath routing (SMR) that establishes and utilizes multiple routes of maximally disjoint paths Providing multiple routes helps minimizing route recovery process and control message overhead Our protocol uses a per-packet allocation scheme to distribute data packets into multiple paths of active sessions This traffic distribution efficiently utilizes available network resources and prevents nodes of the route from being congested in heavily loaded traffic situations We evaluate the performance of our scheme using extensive simulation

Routing with guaranteed delivery in ad hoc wireless networks

Abstract: We consider routing problems in ad hoc wireless networks modeled as unit graphs in which nodes are points in the plane and two nodes can communicate if the distance between them is less than some fixed unit. We describe the first distributed algorithms for routing that do not require duplication of packets or memory at the nodes and yet guarantee that a packet is delivered to its destination. These algorithms can be extended to yield algorithms for broadcasting and geocasting that do not require packet duplication. A by product of our results is a simple distributed protocol for extracting a planar subgraph of a unit graph. We also present simulation results on the performance of our algorithms.

Energy efficient routing in wireless sensor networks

Abstract: Wireless sensor nodes can be deployed on a battlefield and organize themselves in a large-scale ad-hoc network. Traditional routing protocols do not take into account that a node contains only a limited energy supply. Optimal routing tries to maximize the duration over which the sensing task can be performed, but requires future knowledge. As this is unrealistic, we derive a practical guideline based on the energy histogram and develop a spectrum of new techniques to enhance the routing in sensor networks. Our first approach aggregates packet streams in a robust way, resulting in energy reductions of a factor 2 to 3. Second, we argue that a more uniform resource utilization can be obtained by shaping the traffic flow. Several techniques, which rely only on localized metrics are proposed and evaluated. We show that they can increase the network lifetime up to an extra 90% beyond the gains of our first approach.

Power-aware localized routing in wireless networks

Abstract: A cost aware metric for wireless networks based on remaining battery power at nodes was proposed for shortest-cost routing algorithms, assuming constant transmission power. Power-aware metrics, where transmission power depends on distance between nodes and corresponding shortest power algorithms were also proposed. We define a power-cost metric based on the combination of both node's lifetime and distance-based power metrics. We investigate some properties of power adjusted transmissions and show that, if additional nodes can be placed at desired locations between two nodes at distance d, the transmission power can be made linear in d as opposed to d/sup /spl alpha// dependence for /spl alpha/ /spl ges/ 2. This provides basis for power, cost, and power-cost localized routing algorithms where nodes make routing decisions solely on the basis, of location of their neighbors and destination. The power-aware routing algorithm attempts to minimize the total power needed to route a message between a source and a destination. The cost-aware routing algorithm is aimed at extending the battery's worst-case lifetime at each node. The combined power-cost localized routing algorithm attempts to minimize the total power needed and to avoid nodes with a short battery's remaining lifetime. We prove that the proposed localized power, cost, and power-cost efficient routing algorithms are loop-free and show their efficiency by experiments.

An analysis of the optimum node density for ad hoc mobile networks

Abstract: An ad hoc mobile network is a collection of nodes, each of which communicates over wireless channels and is capable of movement. Wireless nodes have the unique capability of transmission at different power levels. As the transmission power is varied, a tradeoff exists between the number of hops from source to destination and the overall bandwidth available to individual nodes. Because both battery life and channel bandwidth are limited resources in mobile networks, it is important to ascertain the effects different transmission powers have on the overall performance of the network. This paper explores the nature of this transmission power tradeoff in mobile networks to determine the optimum node density for delivering the maximum number of data packets. It is shown that there does not exist a global optimum density, but rather that, to achieve this maximum, the node density should increase as the rate of node movement increases.

The performance of query control schemes for the zone routing protocol

Abstract: In this paper, we study the performance of route query control mechanisms for the Zone Routing Protocol (ZRP) for ad hoc networks. ZRP proactively maintains routing information for a local neighborhood (routing zone), while reactively acquiring routes to destinations beyond the routing zone. This hybrid routing approach can be more efficient than traditional routing schemes. However, without proper query control techniques, the ZRP cannot provide the expected reduction in the control traffic.Our proposed query control schemes exploit the structure of the routing zone to provide enhanced detection and prevention of overlapping queries. These techniques can be applied to single- or multiple-channel ad hoc networks to improve both the delay and control traffic performance of ZRP. Our query control mechanisms allow ZRP to provide routes to all accessible network nodes, with less control traffic than purely proactive link state or purely reactive route discovery, and with less delay than conventional flood searching.

Online power-aware routing in wireless Ad-hoc networks

Abstract: This paper discusses online power-aware routing in large wireless ad-hoc networks for applications where the message sequence is not known. We seek to optimize the lifetime of the network. We show that online power-aware routing does not have a constant competitive ratio to the off-line optimal algorithm. We develop an approximation algorithm called max-min zPmin that has a good empirical competitive ratio. To ensure scalability, we introduce a second online algorithm for power-aware routing. This hierarchical algorithm is called zone-based routing. Our experiments show that its performance is quite good.

Minimum-energy broadcast routing in static ad hoc wireless networks

Abstract: Energy conservation is a critical issue in ad hoc wireless networks for node and network life, as the nodes are powered by batteries only. One major approach for energy conservation is to route a communication session along the routes which requires the lowest total energy consumption. This optimization problem is referred to as minimum-energy routing. While minimum-energy unicast routing can be solved in polynomial time by shortest-path algorithms, it remains open whether minimum-energy broadcast routing can be solved in polynomial time, despite the NP-hardness of its general graph version. Previously three greedy heuristics were proposed in Wieselthier et al. (2000): MST (minimum spanning tree), SPT (shortest-path tree), and BIP (broadcasting incremental power). They have been evaluated through simulations in Wieselthier et al.], but little is known about their analytical performance. The main contribution of this paper is the quantitative characterization of their performances in terms of approximation ratios. By exploring geometric structures of Euclidean MSTs, we have been able to prove that the approximation ratio of MST is between 6 and 12, and the approximation ratio of BIP is between /sup 13///sub 3/ and 12. On the other hand, the approximation ratio of SPT is shown to be at least /sup n///sub 2/, where n is the number of receiving nodes. To our best knowledge, these are the first analytical results for minimum-energy broadcasting.

Geographical routing using partial information for wireless ad hoc networks

Abstract: This paper presents an algorithm for routing in wireless and ad hoc networks using information regarding the geographic location of the nodes. The algorithm, which is a new type of distributed, adaptive and asynchronous algorithm, is known as a geographical routing algorithm (GRA). The authors describe the GRA, and discuss it in relation to other routing algorithms in the literature. A system model and a problem statement are presented. Issues related to position information inaccuracy and inconsistency, and mobility are discussed, along with simulation results.

Geographical routing using partial information for wireless ad hoc networks

Abstract: We present an algorithm for routing in wireless ad hoc networks using information about the geographical location of the nodes. We assume each node knows its geographical position and the position of the node to which it wants to send a packet. Initially, the nodes know only their neighbors. But over time they discover other nodes in the network. The routing table at a node S is a list , where p/sub i/ is a geographical position and S/sub i/ is a neighbor of node S. When node S receives a packet for a node D at position pos(D), it finds the p/sub i/ in its routing table which is closest to pos(D) and forwards the packet to the neighbor S/sub i/. We prove the correctness of the algorithm and show that our algorithm naturally aggregates the nodes so that the routing tables remain small. We show that the mean routing table size is O(L~logn), where L~ is the average number of hops between two nodes and n is the number of nodes in the network. We also present methods for taking positional errors, node failures and mobility into account. We justify the results through simulation.

Geometric spanner for routing in mobile networks

Abstract: We propose a new routing graph, the Restricted Delaunay Graph (RDG), for ad hoc networks. Combined with a node clustering algorithm RDG can be used as an underlying graph for geographic routing protocols. This graph has the following attractive properties: (1) it is a planar graph; (2) between any two nodes there exists a path in the RDG whose length, whether measured in terms of topological or Euclidean distance, is only a constant times the optimum length possible; and (3) the graph can be maintained efficiently in a distributed manner when the nodes move around. Furthermore, each node only needs constant time to make routing decisions. We also show by simulation that the RDG outperforms the previously proposed routing graphs under the Greedy Perimeter Stateless Routing (GPSR) protocol. In addition, we investigate theoretical bounds on the quality of paths discovered using GPSR

The impact of Internet policy and topology on delayed routing convergence

Abstract: This paper examines the role inter-domain topology and routing policy play in the process of delayed Internet routing convergence. In previous work, we showed that the Internet lacks effective inter-domain path fail-over. Unlike circuit-switched networks which exhibit fail-over on the order of milliseconds, we found Internet backbone routers may take tens of minutes to reach a consistent view of the network topology after a fault. In this paper, we expand an our earlier work by exploring the impact of specific Internet provider policies and topologies on the speed of routing convergence. Based on data from the experimental injection and measurement of several hundred thousand inter-domain routing faults, we show that the time for end-to-end Internet convergence depends on the length of the longest possible backup autonomous system path between a source and destination node. We also demonstrate significant variation in the convergence behavior of Internet service providers, with the larger providers exhibiting the fastest convergence latencies. Finally, we discuss possible modifications to BGP and provider routing policies which if deployed, would improve inter-domain routing convergence.

Methods and apparatus for displaying a travel route and/or generating a list of places of interest located near the travel route

Abstract: An automated travel planning apparatus includes three separate databases, including a map database for storing bit-mapped images covering numerous geographic regions, a routing database for storing node, link, and shape data for roads geographically located within the geographic regions and for storing place data indicating the geographic location of places such as towns and cities, and a places of interest database containing the geographic locations of numerous places of interest. A processor within the automated travel planning apparatus may be divided into several functional components, including a map selection component, a routing component, and a place selection component. In response to user input at the user interface, the map selection component chooses a bit-mapped image from the map database for display on the display monitor. After a user selects, via the user interface, a departure point and a destination point, the routing component employs the routing database to generate and display a route between the selected departure and destination points. If the user requests a list of places near the displayed route, the place selection component employs the places of interest database to generate and display a list of places of interest which are within a predetermined distance of the generated route.

MP-DSR: a QoS-aware multi-path dynamic source routing protocol for wireless ad-hoc networks

Abstract: Routing in wireless ad-hoc networks has received significant attention in the literature due to the fact that the dynamic behavior of these networks poses many technical challenges on the design of an effective routing scheme. Though on-demand routing approaches have been shown to perform well, they generally lack the support for quality-of-service (QoS) with respect to data transmission. In order to select a subset of end-to-end paths to provide increased stability and reliability of routes, a new QoS metric, end-to-end reliability, is defined and emphasized. We present a distributed multi-path dynamic source routing protocol (MP-DSR)for wireless ad-hoc networks to improve QoS support with respect to end-to-end reliability. Our protocol forwards outgoing packets along multiple paths that are subject to a particular end-to-end reliability requirement. A simulation study is performed to demonstrate the effectiveness of our proposed protocol, particularly the fact that MP-DSR achieves a higher rate of successful packet delivery than existing best-effort ad-hoc routing protocols, such as the dynamic source routing (DSR).

Multipath routing in the presence of frequent topological changes

Abstract: In this article we propose a framework for multipath routing in mobile ad hoc networks and provide its analytical evaluation. The instability of the topology (e.g., failure of links) in these types of networks, due to nodal mobility and changes in wireless propagation conditions, makes transmission of time-sensitive information a challenging problem. To combat this inherent unreliability of these networks, we propose a routing scheme that uses multiple paths simultaneously by splitting the information among the multitude of paths, to increase the probability that the essential portion of the information is received at the destination without incurring excessive delay. Our scheme works by adding some overhead to each packet, which is calculated as a linear function of the original packet bits. The resulting packet (information and overhead) is fragmented into smaller blocks and distributed over the available paths. Our goal is, given the failure probabilities of the paths, to find the optimal way to fragment and then distribute the blocks to the paths so that the probability of reconstructing the original information at the destination is maximized. Our algorithm has low time complexity, which is crucial since the path failure characteristics vary with time and the optimal block distribution has to be recalculated in real time.

Scalable routing protocol for ad hoc networks

Abstract: In this paper we present a scalable routing protocol for ad hoc networks. The protocol is based on a geographic location management strategy that keeps the overhead of routing packets relatively small. Nodes are assigned home regions and all nodes within a home region know the approximate location of the registered nodes. As nodes travel, they send location update messages to their home regions and this information is used to route data packets. In this paper, we derive theoretical performance results for the protocol and prove that the control packet overhead scales linearly with node speed and N3/2 with increasing number of nodes. These results indicate that our protocol is well suited to relatively large ad hoc networks where nodes travel at high speed. Finally, we use simulations to validate our analytical model.

Routing with load balancing in wireless Ad hoc networks

Abstract: An ad hoc wireless mobile network is an infrastructure-less mobile network that has no fixed routers; instead, all nodes are capable of movement and can be connected dynamically in an arbitrary manner. In order to facilitate communication of mobile nodes that may not be within the wireless range of each other, an efficient routing protocol is used to discover routes between nodes so that messages may be delivered in a timely manner. In this paper, we present a novel Load-Balanced Ad hoc Routing (LBAR) protocol for communication in wireless ad hoc networks. LBAR defines a new metric for routing known as the degree of nodal activity to represent the load on a mobile node. In LBAR routing information on all paths from source to destination are forwarded through setup messages to the destination. Setup messages include nodal activity information of all nodes on the traversed path. After collecting information on all possible paths, the destination then makes a selection of the path with the best-cost value and sends an acknowledgement to the source node. LBAR also provides efficient path maintenance to patch up broken links by detouring traffic to the destination. A comprehensive simulation study was conducted to evaluate the performance of the proposed scheme. Performance results show that LBAR outperforms existing ad hoc routing protocols in terms of packet delivery and average end-to-end delay.

Dynamic routing of locally restorable bandwidth guaranteed tunnels using aggregated link usage information

Abstract: We consider a new QoS routing problem which requires the on-line routing of a bandwidth guaranteed path along with the setting up of bypass paths for every link or node traversed by the primary active path. The bypass paths are used for fast local restoration where upon a link or node failure, the first upstream node re-establishes path continuity (with bandwidth guarantees) by switching to the bypass path for the failed node or link, The routing objective is to minimize the bandwidth usage for each connection so as optimize use of network resources while protecting against single node or link failure. Bandwidth efficiency is achieved by exploiting the potential for inter-demand and intra-demand backup bandwidth sharing. We develop a new algorithm for this routing problem which only uses aggregated link usage information (total bandwidth consumed on each link by active paths, total bandwidth consumed on each link by backup paths, and the residual bandwidths) that is easily obtainable by proposed routing protocol extensions. We show that the algorithm performs well in terms of the number of rejected requests and the total bandwidth used, The main use of this algorithm is for MPLS network routing and for wavelength routing in optical networks with wavelength conversion.

Apparatus, and associated method, for routing packet data in an ad hoc wireless communication system

Abstract: Apparatus, and an associated method, by which to route packets of data between a data source node (18-1) and a data destination node (18-6) in an ad hoc, wireless network, such as a Bluetooth scatternet (10). Data routing tables (26, 28, 32) are provided to each node, and header information extracted from a packet header (36) is used by such tables (26, 28, 32). Routing of a packet of data is effectuated in a hop-by-hop manner to effectuate the communication of the packet from the data source node (18-1) to the data destination node (18-6).

Routing in Trees

Abstract: This article focuses on routing messages along shortest paths in tree networks, using compact distributed data structures. We mainly prove that n-node trees support routing schemes with message headers, node addresses, and local memory space of size O(log n) bits, and such that every local routing decision is taken in constant time. This improves the best known routing scheme by a factor of O(log n) in term of both memory requirements and routing time. Our routing scheme requires headers and addresses of size slightly larger than log n, motivated by an inherent trade-off between address-size and memory space, i.e., any routing scheme with addresses on log n bits requires Ω(√n) bits of local memory-space. This shows that a little variation of the address size, e.g., by an additive O(log n) bits factor, has a significant impact on the local memory space.

Integrated dynamic IP and wavelength routing in IP over WDM networks

Abstract: This paper develops an algorithm for integrated dynamic routing of bandwidth guaranteed paths in IP over WDM networks. By integrated routing, we mean routing taking into account the combined topology and resource usage information at the IP and optical layers. Typically, routing in IP over WDM networks has been separated into routing at the IP layer taking only IP layer information into account, and wavelength routing at the optical layer taking only optical network information into account. The motivation for integrated routing is the potential for better network usage, and this is a topic which has not been been studied extensively. We develop an integrated routing algorithm that determines (1) whether to route an arriving request over the existing topology or whether it is better to open new wavelength paths. Sometimes it is better to open new wavelength paths even if it feasible to route the current demand over the existing IP topology due to previously set-up wavelength paths. 2) For routing over the existing IP-level topology, compute "good" routes. (3) If new wavelength paths are to be set-up, determine the routers amongst which new wavelength paths are to be set-up and compute "good" routes for these new wavelength paths. The performance objective is the accomodation of as many requests as possible without requiring any a priori knowledge regarding future arrivals. The route computations account for the presence or absence of wavelength conversion capabilities at optical crossconnects. We show that the developed scheme performs very well in terms of performance metrics such as the number of rejected demands.

Load-balancing routing for wireless access networks

Abstract: The widespread use of wireless devices presents new challenges for network operators, who need to provide service to ever larger numbers of mobile end users, while ensuring quality-of-service guarantees. We describe a new distributed routing algorithm that performs dynamic load-balancing for wireless access networks. The algorithm constructs a load-balanced backbone tree, which simplifies routing and avoids per-destination state for routing and per-flow state for QoS reservations. We evaluate the performance of the algorithm using several metrics including adaptation to mobility, degree of load-balance, bandwidth blocking rate, and convergence speed. We find that the algorithm achieves better network utilization by lowering bandwidth blocking rates than other methods.

Evaluating the impact of stale link state on quality-of-service routing

Abstract: Quality-of-service (QoS) routing satisfies application performance requirements and optimizes network resource usage by selecting paths based on connection traffic parameters and link load information. However, distributing link state imposes significant bandwidth and processing overhead on the network. This paper investigates the performance tradeoff between protocol overhead and the quality of the routing decisions in the context of the source-directed link state routing protocols proposed for IP and ATM networks. We construct a detailed model of QoS routing that parameterizes the path-selection algorithm, link-cost function, and link state update policy. Through extensive simulation experiments with several network topologies and traffic patterns, we uncover the effects of stale link state information and random fluctuations in traffic load on the routing and setup overheads. We then investigate how inaccuracy of link state information interacts with the size and connectivity of the underlying topology. Finally, we show that tuning the coarseness of the link-cost metric to the inaccuracy of underlying link state information reduces the computational complexity of the path-selection algorithm without significantly degrading performance. This work confirms and extends earlier studies, and offers new insights for designing efficient quality-of-service routing policies in large networks.

A scalable location management scheme in mobile ad-hoc networks

Abstract: In ad-hoc networks, geographical routing protocols take advantage of location information so that stateless and efficient routing is feasible. However such routing protocols are heavily dependent on the existence of scalable location management services. We present a novel scheme to perform scalable location management. With any location management schemes, a specific node, A, in the network trusts a small subset of nodes, namely its location servers, and periodically updates them with its location. Our approach adopts a similar strategy, but a different and original approach to select such location servers. First, we present a selection algorithm used to designate location servers of a node by its identifier. Second, we propose a hierarchical addressing model for mobile ad-hoc networks, where node locations could be represented at different accuracy levels. With this approach, different location servers may carry location information of different levels of accuracy and only a small set of location servers needs to be updated when the node moves. Through rigorous theoretical analysis, we are able to show that the control message overhead is bounded under our scheme. Finally, simulation results are presented to demonstrate the performance of our location management scheme.

Survivable routing of logical topologies in WDM networks

Abstract: Network restoration is often done at the electronic layer by rerouting traffic along a redundant path. With wavelength division multiplexing (WDM) as the underlying physical layer, it is possible that both the primary and backup paths traverse the same physical links and would fail simultaneously in the event of a link failure. It is therefore critical that lightpaths are routed in such a way that a single link failure would not disconnect the network. We call such a routing survivable and develop algorithms for survivable routing of a logical topology. We prove necessary and sufficient conditions for a routing to be survivable and use this condition to formulate the problem as an integer linear program. We use our new formulation to route various logical topologies over a number of different physical topologies and show that this new approach offers a much greater degree of protection than alternative routing schemes such as shortest path routing and a greedy routing algorithm.

Location awareness in ad hoc wireless mobile networks

Abstract: Networks composed of dynamically repositioning mobile hosts require location awareness to provide new geographic services and to maximize routing efficiency and quality of service. Because wireless networks can operate in a 3D physical environment, exploiting mobile hosts' location information is both natural and inevitable. Emerging geographic services based on mobile ad-hoc networks (manets) must confront several challenges, including how to increase positioning accuracy and how to establish a connection from location information to the vast body of Web data, as in a tour-guide system for example.

Profile-Based Routing: A New Framework for MPLS Traffic Engineering

Abstract: We present a new algorithm and framework for dynamic routing of bandwidth guaranteed flows. The problem is motivated by the need todynamically set up bandwidth guaranteed paths in carrier and ISP networks. Traditional routing algorithms such as minimum hop routing or widest path routing do not take advantage of any knowledge about the traffic distribution or ingress-egress pairs, and therefore can often lead to severe network underutilization. Our work is inspired by the recently proposed "minimum interference routing" algorithm (MIRA) of Kodialam and Lakshman, but it improves on their approach in several ways. Our main idea is to use a "traffic profile" of the network, obtained by measurements or service level agreements (SLAs), as a rough predictor of the future traffic distribution. We use this profile to solve a multicommodity network flow problem, whose output is used both to guide our online path selection algorithm as well as impose admission control. The offline multicommodity solution seems very effective at distributing the routes and avoiding bottlenecks around hot spots. In particular, our algorithm can anticipate a flow's blocking effect on groups of ingress-egress pairs, while MIRA only considers one ingress-egress pair at a time. Our simulation results show that the new algorithm outperforms shortest path, widest path, and minimum interference routing algorithms on several metrics, including the fraction of requests routed and the fraction of requested bandwidth routed. Finally, the framework is quite general and can be extended in numerous ways to accommodate a variety of traffic management priorities in the network.