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Showing papers on "Destination-Sequenced Distance Vector routing published in 2010"


Journal ArticleDOI
TL;DR: A simulated annealing (SA) based heuristic for solving the location routing problem is proposed and it is indicated that the proposed SALRP heuristic is competitive with other well-known algorithms.

271 citations


Journal ArticleDOI
TL;DR: It is observed that carry-and-forward is the new and key consideration for designing all routing protocols in VANETs, and min-delay and delay-bounded routing protocols for VANets are discussed.
Abstract: Vehicular Ad hoc Network (VANET), a subclass of mobile ad hoc networks (MANETs), is a promising approach for the intelligent transportation system (ITS). The design of routing protocols in VANETs is important and necessary issue for support the smart ITS. The key difference of VANET and MANET is the special mobility pattern and rapidly changeable topology. It is not effectively applied the existing routing protocols of MANETs into VANETs. In this investigation, we mainly survey new routing results in VANET. We introduce unicast protocol, multicast protocol, geocast protocol, mobicast protocol, and broadcast protocol. It is observed that carry-and-forward is the new and key consideration for designing all routing protocols in VANETs. With the consideration of multi-hop forwarding and carry-and-forward techniques, min-delay and delay-bounded routing protocols for VANETs are discussed in VANETs. Besides, the temporary network fragmentation problem and the broadcast storm problem are further considered for designing routing protocols in VANETs. The temporary network fragmentation problem caused by rapidly changeable topology influence on the performance of data transmissions. The broadcast storm problem seriously affects the successful rate of message delivery in VANETs. The key challenge is to overcome these problems to provide routing protocols with the low communication delay, the low communication overhead, and the low time complexity. The challenges and perspectives of routing protocols for VANETs are finally discussed.

243 citations


Proceedings ArticleDOI
Hussam Abu-Libdeh1, Paolo Costa1, Antony Rowstron1, Greg O'Shea1, Austin Donnelly1 
30 Aug 2010
TL;DR: This paper designs an extended routing service allowing easy implementation of application-specific routing protocols on CamCube, and demonstrates the benefits and network-level impact of running multiple routing protocols.
Abstract: Building distributed applications that run in data centers is hard. The CamCube project explores the design of a shipping container sized data center with the goal of building an easier platform on which to build these applications. CamCube replaces the traditional switch-based network with a 3D torus topology, with each server directly connected to six other servers. As in other proposals, e.g. DCell and BCube, multi-hop routing in CamCube requires servers to participate in packet forwarding. To date, as in existing data centers, these approaches have all provided a single routing protocol for the applications.In this paper we explore if allowing applications to implement their own routing services is advantageous, and if we can support it efficiently. This is based on the observation that, due to the flexibility offered by the CamCube API, many applications implemented their own routing protocol in order to achieve specific application-level characteristics, such as trading off higher-latency for better path convergence. Using large-scale simulations we demonstrate the benefits and network-level impact of running multiple routing protocols. We demonstrate that applications are more efficient and do not generate additional control traffic overhead. This motivates us to design an extended routing service allowing easy implementation of application-specific routing protocols on CamCube. Finally, we demonstrate that the additional performance overhead incurred when using the extended routing service on a prototype CamCube is very low.

242 citations


Journal ArticleDOI
TL;DR: This paper first breaks up existing routing strategies into a small number of common and tunable routing modules, and shows how and when a given routing module should be used, depending on the set of network characteristics exhibited by the wireless application.
Abstract: Communication networks, whether they are wired or wireless, have traditionally been assumed to be connected at least most of the time. However, emerging applications such as emergency response, special operations, smart environments, VANETs, etc. coupled with node heterogeneity and volatile links (e.g. due to wireless propagation phenomena and node mobility) will likely change the typical conditions under which networks operate. In fact, in such scenarios, networks may be mostly disconnected, i.e., most of the time, end-to-end paths connecting every node pair do not exist. To cope with frequent, long-lived disconnections, opportunistic routing techniques have been proposed in which, at every hop, a node decides whether it should forward or store-and-carry a message. Despite a growing number of such proposals, there still exists little consensus on the most suitable routing algorithm(s) in this context. One of the reasons is the large diversity of emerging wireless applications and networks exhibiting such "episodic" connectivity. These networks often have very different characteristics and requirements, making it very difficult, if not impossible, to design a routing solution that fits all. In this paper, we first break up existing routing strategies into a small number of common and tunable routing modules (e.g. message replication, coding, etc.), and then show how and when a given routing module should be used, depending on the set of network characteristics exhibited by the wireless application. We further attempt to create a taxonomy for intermittently connected networks. We try to identify generic network characteristics that are relevant to the routing process (e.g., network density, node heterogeneity, mobility patterns) and dissect different "challenged" wireless networks or applications based on these characteristics. Our goal is to identify a set of useful design guidelines that will enable one to choose an appropriate routing protocol for the application or network in hand. Finally, to demonstrate the utility of our approach, we take up some case studies of challenged wireless networks, and validate some of our routing design principles using simulations.

232 citations


Journal ArticleDOI
TL;DR: A cross-layer opportunistic spectrum access and dynamic routing algorithm for cognitive radio networks, which is called the routing and dynamic spectrum-allocation (ROSA) algorithm, which aims to maximize the network throughput by performing joint routing, dynamic spectrum allocation, scheduling, and transmit power control.
Abstract: Throughput maximization is one of the main challenges in cognitive radio ad hoc networks, where the availability of local spectrum resources may change from time to time and hop by hop. For this reason, a cross-layer opportunistic spectrum access and dynamic routing algorithm for cognitive radio networks is proposed, which is called the routing and dynamic spectrum-allocation (ROSA) algorithm. Through local control actions, ROSA aims to maximize the network throughput by performing joint routing, dynamic spectrum allocation, scheduling, and transmit power control. Specifically, the algorithm dynamically allocates spectrum resources to maximize the capacity of links without generating harmful interference to other users while guaranteeing a bounded bit error rate (BER) for the receiver. In addition, the algorithm aims to maximize the weighted sum of differential backlogs to stabilize the system by giving priority to higher capacity links with a high differential backlog. The proposed algorithm is distributed, computationally efficient, and has bounded BER guarantees. ROSA is shown through numerical model-based evaluation and discrete-event packet-level simulations to outperform baseline solutions, leading to a high throughput, low delay, and fair bandwidth allocation.

232 citations


Journal ArticleDOI
01 Jan 2010
TL;DR: The experimental results show that these immigrants and memory-based GAs can quickly adapt to environmental changes and produce high-quality solutions after each change and this paper considers MANETs as target systems because they represent new-generation wireless networks.
Abstract: In recent years, the static shortest path (SP) problem has been well addressed using intelligent optimization techniques, e.g., artificial neural networks, genetic algorithms (GAs), particle swarm optimization, etc. However, with the advancement in wireless communications, more and more mobile wireless networks appear, e.g., mobile networks [mobile ad hoc networks (MANETs)], wireless sensor networks, etc. One of the most important characteristics in mobile wireless networks is the topology dynamics, i.e., the network topology changes over time due to energy conservation or node mobility. Therefore, the SP routing problem in MANETs turns out to be a dynamic optimization problem. In this paper, we propose to use GAs with immigrants and memory schemes to solve the dynamic SP routing problem in MANETs. We consider MANETs as target systems because they represent new-generation wireless networks. The experimental results show that these immigrants and memory-based GAs can quickly adapt to environmental changes (i.e., the network topology changes) and produce high-quality solutions after each change.

202 citations


Journal ArticleDOI
TL;DR: GeoDTN+Nav is proposed, a hybrid geographic routing solution enhancing the standard greedy and recovery modes exploiting the vehicular mobility and on-board vehicular navigation systems to efficiently deliver packets even in partitioned networks by using delay tolerant forwarding in sparse networks.
Abstract: Position-based routing has proven to be well suited for highly dynamic environment such as Vehicular Ad Hoc Networks (VANET) due to its simplicity. Greedy Perimeter Stateless Routing (GPSR) and Greedy Perimeter Coordinator Routing (GPCR) both use greedy algorithms to forward packets by selecting relays with the best progress towards the destination or use a recovery mode in case such solutions fail. These protocols could forward packets efficiently given that the underlying network is fully connected. However, the dynamic nature of vehicular network, such as vehicle density, traffic pattern, and radio obstacles could create unconnected networks partitions. To this end, we propose GeoDTN+Nav, a hybrid geographic routing solution enhancing the standard greedy and recovery modes exploiting the vehicular mobility and on-board vehicular navigation systems to efficiently deliver packets even in partitioned networks. GeoDTN+Nav outperforms standard geographic routing protocols such as GPSR and GPCR because it is able to estimate network partitions and then improves partitions reachability by using a store-carry-forward procedure when necessary. We propose a virtual navigation interface (VNI) to provide generalized route information to optimize such forwarding procedure. We finally evaluate the benefit of our approach first analytically and then with simulations. By using delay tolerant forwarding in sparse networks, GeoDTN+Nav greatly increases the packet delivery ratio of geographic routing protocols and provides comparable routing delay to benchmark DTN algorithms.

181 citations


Proceedings ArticleDOI
20 Jun 2010
TL;DR: This paper compares Mobile Ad-Hoc network routing protocols DSDV, AODV and DSR using network simulator NS2.34 and the performance matrix includes PDR, Throughput, End to End Delay, Routing overhead.
Abstract: Mobile Ad-Hoc networks are highly dynamic networks characterized by the absence of physical infrastructure. Nodes of these networks functions as a routers which discovers and maintains the routes to other nodes in the network. In such networks, nodes are able to move and synchronize with their neighbors. Due to mobility, connections in the network can change dynamically and nodes can be added and removed at any time. In this paper, we are going to compare Mobile Ad-Hoc network routing protocols DSDV, AODV and DSR using network simulator NS2.34. We have compared the performance of three protocols together and individually too. The performance matrix includes PDR (Packet Delivery Ratio), Throughput, End to End Delay, Routing overhead. We are comparing the performance of routing protocols when packet size changes, when time interval between packet sending changes, when mobility of nodes changes.

173 citations


Journal ArticleDOI
TL;DR: This paper addresses an important combination of three-dimensional loading and vehicle routing, known as the Three-Dimensional Loading Capacitated Vehicle Routing Problem, by means of an Ant Colony Optimization algorithm that makes use of fast packing heuristics for the loading.

169 citations


Proceedings ArticleDOI
30 Aug 2010
TL;DR: The model of energy-aware routing in data center network is established, and a heuristic algorithm is designed to achieve the idea, which shows that energy- aware routing can effectively save power consumed by network devices.
Abstract: The goal of data center network is to interconnect the massive number of data center servers, and provide efficient and fault-tolerant routing service to upper-layer applications. To overcome the problem of tree architecture in current practice, many new network architectures are proposed, represented by Fat-Tree, BCube, and etc. A consistent theme in these new architectures is that a large number of network devices are used to achieve 1:1 oversubscription ratio. However, at most time, data center traffic is far below the peak value. The idle network devices will waste significant amount of energy, which is now a headache for many data center owners.In this paper, we discuss how to save energy consumption in high-density data center networks in a routing perspective. We call this kind of routing energy-aware routing. The key idea is to use as few network devices to provide the routing service as possible, with no/little sacrifice on the network performance. Meanwhile, the idle network devices can be shutdown or put into sleep mode for energy saving. We establish the model of energy-aware routing in data center network, and design a heuristic algorithm to achieve the idea. Our simulation in typical data center networks shows that energy-aware routing can effectively save power consumed by network devices.

168 citations


Journal ArticleDOI
TL;DR: This paper presents rapid, an intentional DTN routing protocol that can optimize a specific routing metric such as the worst-case delivery delay or the fraction of packets that are delivered within a deadline, and significantly outperforms existing routing protocols for several metrics.
Abstract: Routing protocols for disruption-tolerant networks (DTNs) use a variety of mechanisms, including discovering the meeting probabilities among nodes, packet replication, and network coding. The primary focus of these mechanisms is to increase the likelihood of finding a path with limited information, and so these approaches have only an incidental effect on such routing metrics as maximum or average delivery delay. In this paper, we present rapid, an intentional DTN routing protocol that can optimize a specific routing metric such as the worst-case delivery delay or the fraction of packets that are delivered within a deadline. The key insight is to treat DTN routing as a resource allocation problem that translates the routing metric into per-packet utilities that determine how packets should be replicated in the system. We evaluate rapid rigorously through a prototype deployed over a vehicular DTN testbed of 40 buses and simulations based on real traces. To our knowledge, this is the first paper to report on a routing protocol deployed on a real outdoor DTN. Our results suggest that rapid significantly outperforms existing routing protocols for several metrics. We also show empirically that for small loads, RAPID is within 10% of the optimal performance.

Journal ArticleDOI
TL;DR: A global dynamic routing strategy for network systems based on the information of the queue length of nodes, which improves the traffic capacity and the system capacity remains constant, while the travel time for packets increases.
Abstract: Traffic is essential for many dynamic processes on networks. The efficient routing strategy [G. Yan, T. Zhou, B. Hu, Z. Q. Fu, and B. H. Wang, Phys. Rev. E 73, 046108 (2006)] can reach a very high capacity of more than ten times of that with shortest path strategy. In this paper, we propose a global dynamic routing strategy for network systems based on the information of the queue length of nodes. Under this routing strategy, the traffic capacity is further improved. With time delay of updating node queue lengths and the corresponding paths, the system capacity remains constant, while the travel time for packets increases.

Journal ArticleDOI
TL;DR: Simulation results show that the EBGR scheme significantly outperforms existing protocols in wireless sensor networks with highly dynamic network topologies and extends to lossy sensor networks to provide energy-efficient routing in the presence of unreliable communication links.
Abstract: Geographic routing is an attractive localized routing scheme for wireless sensor networks (WSNs) due to its desirable scalability and efficiency. Maintaining neighborhood information for packet forwarding can achieve a high efficiency in geographic routing, but may not be appropriate for WSNs in highly dynamic scenarios where network topology changes frequently due to nodes mobility and availability. We propose a novel online routing scheme, called Energy-efficient Beaconless Geographic Routing (EBGR), which can provide loop-free, fully stateless, energy-efficient sensor-to-sink routing at a low communication overhead without the help of prior neighborhood knowledge. In EBGR, each node first calculates its ideal next-hop relay position on the straight line toward the sink based on the energy-optimal forwarding distance, and each forwarder selects the neighbor closest to its ideal next-hop relay position as the next-hop relay using the Request-To-Send/Clear-To-Send (RTS/CTS) handshaking mechanism. We establish the lower and upper bounds on hop count and the upper bound on energy consumption under EBGR for sensor-to-sink routing, assuming no packet loss and no failures in greedy forwarding. Moreover, we demonstrate that the expected total energy consumption along a route toward the sink under EBGR approaches to the lower bound with the increase of node deployment density. We also extend EBGR to lossy sensor networks to provide energy-efficient routing in the presence of unreliable communication links. Simulation results show that our scheme significantly outperforms existing protocols in wireless sensor networks with highly dynamic network topologies.

Patent
19 Feb 2010
TL;DR: In this paper, the authors propose an architecture that facilitates load balancing among a plurality of hosts and preserves session affinity to a given host by using a maximally backward compatible hash function to minimize the differences between the old and new routing functions.
Abstract: The invention relates to an architecture that facilitates load balancing among a plurality of hosts and preserve session affinity to a given host. An incoming stream of data packets that include packet sessions is input to one or more forwarding mechanisms for forwarding to one or more hosts. The forwarders generate a routing function that takes into consideration host availability, and distributes session packets according to the routing function. A session is distributed to the same host to preserve session affinity. When host availability changes, a new routing function is generated, such that any new session is routed according to the new routing function and existing sessions are routed according to the old routing function. When the old routing function becomes irrelevant, it is phased out. An optimization utilizes a maximally backward compatible hash function to minimize the differences between the old and new routing functions.

Journal ArticleDOI
TL;DR: This paper provides a review of the most recent developments that had a major impact in the current state-of-the-art of exact algorithms for vehicle routing problems under capacity constraints, with a focus on the basic Capacitated Vehicle Routing Problem (CVRP) and on heterogeneous vehicle routing problem.
Abstract: The solution of a vehicle routing problem calls for the determination of a set of routes, each performed by a single vehicle which starts and ends at its own depot, such that all the requirements of the customers are fulfilled and the global transportation cost is minimized. The routes have to satisfy several operational constraints which depend on the nature of the transported goods, on the quality of the service level, and on the characteristics of the customers and of the vehicles. One of the most common operational constraint addressed in the scientific literature is that the vehicle fleet is capacitated and the total load transported by a vehicle cannot exceed its capacity.

Journal ArticleDOI
TL;DR: This paper proposes a distributed Prediction-based Cognitive Topology Control scheme to provision cognition capability to routing in CR-MANETs and constructs an efficient and reliable topology, which is aimed at mitigating re-routing frequency and improving end-to-end network performance such as throughput and delay.
Abstract: Recent research activities on cognitive radio (CR) have mainly focussed on opportunistic spectrum access and spectrum utilization. However, CR technology will have a significant impact on upper layer performance in wireless networks, particularly in mobile ad hoc networks (MANETs). In this paper, we study topology control and routing issues in CR-MANETs and propose a distributed prediction-based cognitive topology control (PCTC) scheme to provision cognition capability to routing in CR-MANETs. PCTC is a middleware-like cross-layer module residing between CR module and routing. It uses cognitive link availability prediction, which is aware of the interference to primary users and user mobility, to predict the available duration of links. Based on the link prediction, PCTC captures the dynamic changes of the topology and constructs an efficient and reliable topology, which is aimed at mitigating rerouting frequency and improving end-to-end network performance such as throughput and delay. Simulation results are presented to show the effectiveness of the proposed scheme.

Journal ArticleDOI
Xin Li1, Zhiping Jia1, Peng Zhang1, Ruihua Zhang1, Haiyang Wang1 
TL;DR: A trust-based reactive multipath routing protocol, ad hoc on-demand trusted-path distance vector (AOTDV), is proposed for MANETs and the results show that AotDV improves packet delivery ratio and mitigates the impairment from black hole, grey hole and modification attacks.
Abstract: A mobile ad hoc network (MANET) is a self-organised system comprised of mobile wireless nodes. All nodes act as both communicators and routers. Owing to multi-hop routing and absence of centralised administration in open environment, MANETs are vulnerable to attacks by malicious nodes. In order to decrease the hazards from malicious nodes, the authors incorporate the concept of trust to MANETs and build a simple trust model to evaluate neighbours’ behaviours – forwarding packets. Extended from the ad hoc on-demand distance vector (AODV) routing protocol and the ad hoc on-demand multipath distance vector (AOMDV) routing protocol, a trust-based reactive multipath routing protocol, ad hoc on-demand trusted-path distance vector (AOTDV), is proposed for MANETs. This protocol is able to discover multiple loop-free paths as candidates in one route discovery. These paths are evaluated by two aspects: hop counts and trust values. This two-dimensional evaluation provides a flexible and feasible approach to choose the shortest path from the candidates that meet the requirements of data packets for dependability or trust. Furthermore, the authors give a routing example in details to describe the procedures of route discovery and the differences among AODV, AOMDV and AOTDV. Several experiments have been conducted to compare these protocols and the results show that AOTDV improves packet delivery ratio and mitigates the impairment from black hole, grey hole and modification attacks.

Proceedings ArticleDOI
30 Aug 2010
TL;DR: This work proposes an alternative, highly agile approach called backpressure routing for Delay Tolerant Networks (DTN), in which routing and forwarding decisions are made on a per-packet basis, using information about queue backlogs, random walk and data packet scheduling nodes.
Abstract: In this paper we consider an alternative, highly agile In this paper we consider an alternative, highly agile approach called backpressure routing for Delay Tolerant Networks (DTN), in which routing and forwarding decisions are made on a per-packet basis. Using information about queue backlogs, random walk and data packet scheduling nodes can make packet routing and forwarding decisions without the notion of end-to-end routes. To the best of our knowledge, this is the first ever implementation of dynamic backpressure routing in DTNs. Simulation results show that the proposed approach has advantages in terms of DTN networks.

Journal ArticleDOI
TL;DR: The proposed dynamic routing method for supervisory control of multiple automated guided vehicles that are traveling within a layout of a given warehouse has been successfully implemented in the industrial environment in a form of a multiple AGV control system.
Abstract: This paper presents a dynamic routing method for supervisory control of multiple automated guided vehicles (AGVs) that are traveling within a layout of a given warehouse. In dynamic routing a calculated path particularly depends on the number of currently active AGVs' missions and their priorities. In order to solve the shortest path problem dynamically, the proposed routing method uses time windows in a vector form. For each mission requested by the supervisor, predefined candidate paths are checked if they are feasible. The feasibility of a particular path is evaluated by insertion of appropriate time windows and by performing the windows overlapping tests. The use of time windows makes the algorithm apt for other scheduling and routing problems. Presented simulation results demonstrate efficiency of the proposed dynamic routing. The proposed method has been successfully implemented in the industrial environment in a form of a multiple AGV control system.

Journal ArticleDOI
TL;DR: This research investigates distributed clustering scheme and proposes a cluster-based routing protocol for Delay-Tolerant Mobile Networks (DTMNs), showing that it achieves higher delivery ratio and significantly lower overhead and end-to-end delay compared with its non-clustering counterpart.
Abstract: This research investigates distributed clustering scheme and proposes a cluster-based routing protocol for Delay-Tolerant Mobile Networks (DTMNs). The basic idea is to distributively group mobile nodes with similar mobility pattern into a cluster, which can then interchangeably share their resources (such as buffer space) for overhead reduction and load balancing, aiming to achieve efficient and scalable routing in DTMN. Due to the lack of continuous communications among mobile nodes and possible errors in the estimation of nodal contact probability, convergence and stability become major challenges in distributed clustering in DTMN. To this end, an exponentially weighted moving average (EWMA) scheme is employed for on-line updating nodal contact probability, with its mean proven to converge to the true contact probability. Based on nodal contact probabilities, a set of functions including Sync(), Leave(), and Join() are devised for cluster formation and gateway selection. Finally, the gateway nodes exchange network information and perform routing. Extensive simulations are carried out to evaluate the effectiveness and efficiency of the proposed cluster-based routing protocol. The simulation results show that it achieves higher delivery ratio and significantly lower overhead and end-to-end delay compared with its non-clustering counterpart.

01 Jan 2010
TL;DR: This paper is a survey of active research work on routing protocols for MANET, an autonomously self-organized networks without infrastructure support that may experience rapid and unpredictable topology changes.
Abstract: Mobile ad hoc networks (MANETs) are autonomously self-organized networks without infrastructure support. In a mobile ad hoc network, nodes move arbitrarily; therefore the network may experience rapid and unpredictable topology changes. Because nodes in a MANET normally have limited transmission ranges, some nodes cannot communicate directly with each other. Hence, routing paths in mobile ad hoc networks potentially contain multiple hops, and every node in mobile ad hoc networks has the responsibility to act as a router. This paper is a survey of active research work on routing protocols for MANET.

Proceedings ArticleDOI
24 Apr 2010
TL;DR: A new routing protocol for VANET is designed based on the former results, called CBR (Cluster Based Routing), which has obvious improvement in the average routing overhead and small average end to end delay jitter with the increase of vehicles number.
Abstract: With the development of vehicles and mobile Ad Hoc network technology, the Vehicle Ad hoc Network (VANET) has become an emerging field of study It is a challenging problem for searching and maintaining an effective route for transporting some data information In this paper the authors designed a new routing protocol for VANET based on the former results, called CBR (Cluster Based Routing) Compared with other routing protocols, the new one has obvious improvement in the average routing overhead and small average end to end delay jitter with the increase of vehicles number The real-time traffic applications require data transmission delay time to be relatively stable, small average end to end delay jitter with the increase of vehicles number just meets the real-time application needs

Journal ArticleDOI
TL;DR: An optimization problem for a call center with heterogeneous agent pools, in which each pool is distinguished by the speed at which agents in that pool handle calls, is formulated and the resulting routing policy is a threshold policy that determines server pool priorities based on the total number of customers in the system.
Abstract: In a call center, there is a natural trade-off between minimizing customer wait time and fairly dividing the workload among agents of different skill levels. The relevant control is the routing policy, that is, the decision concerning which agent should handle an arriving call when more than one agent is available. We formulate an optimization problem for a call center with heterogeneous agent pools, in which each pool is distinguished by the speed at which agents in that pool handle calls. The objective is to minimize steady-state expected customer wait time subject to a “fairness” constraint on the workload division. We first solve the optimization problem by formulating it as a Markov decision process (MDP), and solving a related linear program. We note that this approach does not in general lead to an optimal policy that has a simple structure. Fortunately, the optimal policy does appear to have a simple structure as the system size grows large, in the Halfin-Whitt many-server heavy-traffic limit regime. Therefore, we solve the diffusion control problem that arises in this regime and interpret its solution as a policy for the original system. The resulting routing policy is a threshold policy that determines server pool priorities based on the total number of customers in the system. We prove that a continuous modification of our proposed threshold routing policy is asymptotically optimal in the Halfin-Whitt limit regime. We furthermore present simulation results to illustrate that our proposed threshold routing policy outperforms a common routing policy used in call centers (that routes to the agent that has been idle the longest).

Proceedings ArticleDOI
21 Jun 2010
TL;DR: This work considers the problem of gathering correlated sensor data by a sink node in a wireless sensor network, and proposes an efficient heuristic algorithm, JRPRA, to solve the general problem.
Abstract: We consider the problem of gathering correlated sensor data by a sink node in a wireless sensor network. We design efficient distributed protocols to maximize the network lifetime subject to nodal energy constraints. Many existing approaches address the routing layer only, but the routing often interacts with physical-layer power control and MAC-layer link access. We present a first effort to maximize the network lifetime by jointly considering the three layers. We first solve the joint power control and routing problem, by assuming that the link access probabilities are known. We show that the problem is convex and propose a distributed algorithm, JRPA, as solution. When the link access probabilities are unknown, we then generalize the problem to encompass all three layers of routing, power control, and link random access. The general problem is non-convex; a duality gap exists when the Lagrangian dual method is employed. We propose an efficient heuristic algorithm, JRPRA, to solve the general problem. Numerical results show that JRPRA is highly effective; particularly, even without the best link access probabilities pre-determined for JRPA, JRPRA achieves extremely competitive performance. Our results also show the convergence of the algorithms and their advantages over existing solutions.

Journal ArticleDOI
TL;DR: This work resolves a conjecture of Papadimitriou and Ratajczak that every 3-connected planar graph admits a greedy embedding into the Euclidean plane and proves a combinatorial condition that guarantees nonembeddability.
Abstract: Geographic Routing is a family of routing algorithms that uses geographic point locations as addresses for the purposes of routing. Such routing algorithms have proven to be both simple to implement and heuristically effective when applied to wireless sensor networks. Greedy Routing is a natural abstraction of this model in which nodes are assigned virtual coordinates in a metric space, and these coordinates are used to perform point-to-point routing. Here we resolve a conjecture of Papadimitriou and Ratajczak that every 3-connected planar graph admits a greedy embedding into the Euclidean plane. This immediately implies that all 3-connected graphs that exclude K 3,3 as a minor admit a greedy embedding into the Euclidean plane. We also prove a combinatorial condition that guarantees nonembeddability. We use this result to construct graphs that can be greedily embedded into the Euclidean plane, but for which no spanning tree admits such an embedding.

Journal ArticleDOI
TL;DR: A novel cluster-based trust-aware routing protocol for MANETs to protect forwarded packets from intermediary malicious nodes and ensures the trustworthiness of cluster-heads by replacing them as soon as they become malicious and can dynamically update the packet path to avoid malicious routes.
Abstract: Routing protocols are the binding force in mobile ad hoc network (MANETs) since they facilitate communication beyond the wireless transmission range of the nodes. However, the infrastructure-less, pervasive, and distributed nature of MANETs renders them vulnerable to security threats. In this paper, we propose a novel cluster-based trust-aware routing protocol (CBTRP) for MANETs to protect forwarded packets from intermediary malicious nodes. The proposed protocol organizes the network into one-hop disjoint clusters then elects the most qualified and trustworthy nodes to play the role of cluster-heads that are responsible for handling all the routing activities. The proposed CBTRP continuously ensures the trustworthiness of cluster-heads by replacing them as soon as they become malicious and can dynamically update the packet path to avoid malicious routes. We have implemented and simulated the proposed protocol then evaluated its performance compared to the clustered based routing protocol (CBRP) as well as the 2ACK approach. Comparisons and analysis have shown the effectiveness of our proposed scheme.

01 Jan 2010
TL;DR: Some basic security concerns in MANET are addressed, operation of wormhole attack and securing the wellknown routing protocol Ad-hoc On Demand Distance Vector are addressed.
Abstract: Summary: In this era of wireless devices, Mobile Ad-hoc Network (MANET) has become an indivisible part for communication for mobile devices. Therefore, interest in research of Mobile Ad-hoc Network has been growing since last few years. In this paper we have discussed some basic routing protocols in MANET like Destination Sequenced Distance Vector, Dynamic Source Routing, Temporally-Ordered Routing Algorithm and Ad-hoc On Demand Distance Vector. Security is a big issue in MANETs as they are infrastructure-less and autonomous. Main objective of writing this paper is to address some basic security concerns in MANET, operation of wormhole attack and securing the wellknown routing protocol Ad-hoc On Demand Distance Vector. This article would be a great help for the people conducting research on real world problems in MANET security.

Proceedings ArticleDOI
01 Feb 2010
TL;DR: A fat-tree routing algorithm that provides a congestion-free, all-to-all shift pattern leveraging on the InfiniBandTM static routing capability is proposed that supports partially populated fat-trees built with switches of arbitrary number of ports and CBB ratios.
Abstract: Clustered systems have become a dominant architecture of scalable high-performance super computers. In these large-scale computers, the network performance and scalability is as critical as the compute-nodes speed. InfiniBandTM has become a commodity networking solution supporting the stringent latency, bandwidth and scalability requirements of these clusters. The network performance is also affected by its topology, packet routing and the communication patterns the distributed application exercises. Fat-trees are the topology structures used for constructing most large clusters as they are scalable, maintain cross-bisectional-bandwidth (CBB), and are practical to build using fixed-arity switches. In this paper, we propose a fat-tree routing algorithm that provides a congestion-free, all-to-all shift pattern leveraging on the InfiniBandTM static routing capability. The algorithm supports partially populated fat-trees built with switches of arbitrary number of ports and CBB ratios. To evaluate the proposed algorithm, detailed switch and host simulation models were developed and multiple fabric topologies were run. The results of these simulations as well as measurements on real clusters show an improvement in all-to-all delay by avoiding congestion on the fabric. Copyright © 2009 John Wiley & Sons, Ltd. The paper was presented in the International Super Computer 2007 conference in Dresden Germany.

01 Jan 2010
TL;DR: A Mobile Ad hoc NETwork (MANET) is a kind of wireless ad-hoc network, and is a self-configuring network of mobile routers connected by wireless links – the union of which forms an arbitrary topology.
Abstract: A Mobile Ad hoc NETwork (MANET) is a kind of wireless ad-hoc network, and is a self-configuring network of mobile routers (and associated hosts) connected by wireless links – the union of which forms an arbitrary topology. The routers are free to move randomly and organize themselves arbitrarily; thus, the network's wireless topology may change rapidly and unpredictably. Such a network may operate in a standalone fashion, or may be connected to the larger Internet.

Journal ArticleDOI
TL;DR: A mobility-based multicast routing algorithm for wireless MANETs wherein the mobility characteristics are stochastic and unknown is proposed, and it is shown that the most stable multicast route is found with a probability as close as to unity by the proper choice of the parameters of the distributed learning automata.