Showing papers on "Wireless ad hoc network published in 2011"

Ad hoc networking

Abstract: Embodiments disclosed herein relate to ad hoc networking. An embodiment includes computing a routing score for a source node based on at least hardware capabilities of the source node, applications available to the source node, and networking capabilities of the source node. The embodiment further includes receiving at the source node, one or more routing scores from intermediate nodes directly or indirectly connected to the source node, and sending the data to the destination node based on at least the routing scores received from each intermediate node and one or more route paths associated with each intermediate node.

Bidirectionally Coupled Network and Road Traffic Simulation for Improved IVC Analysis

Abstract: Recently, many efforts have been made to develop more efficient Inter-Vehicle Communication (IVC) protocols for on-demand route planning according to observed traffic congestion or incidents, as well as for safety applications. Because practical experiments are often not feasible, simulation of network protocol behavior in Vehicular Ad Hoc Network (VANET) scenarios is strongly demanded for evaluating the applicability of developed network protocols. In this work, we discuss the need for bidirectional coupling of network simulation and road traffic microsimulation for evaluating IVC protocols. As the selection of a mobility model influences the outcome of simulations to a great extent, the use of a representative model is necessary for producing meaningful evaluation results. Based on these observations, we developed the hybrid simulation framework Veins (Vehicles in Network Simulation), composed of the network simulator OMNeT++ and the road traffic simulator SUMO. In a proof-of-concept study, we demonstrate its advantages and the need for bidirectionally coupled simulation based on the evaluation of two protocols for incident warning over VANETs. With our developed methodology, we can advance the state-of-the-art in performance evaluation of IVC and provide means to evaluate developed protocols more accurately.

Impact of Vehicles as Obstacles in Vehicular Ad Hoc Networks

Abstract: A thorough understanding of the communications channel between vehicles is essential for realistic modeling of Vehicular Ad Hoc Networks (VANETs) and the development of related technology and applications. The impact of vehicles as obstacles on vehicle-to-vehicle (V2V) communication has been largely neglected in VANET research, especially in simulations. Useful models accounting for vehicles as obstacles must satisfy a number of requirements, most notably accurate positioning, realistic mobility patterns, realistic propagation characteristics, and manageable complexity. We present a model that satisfies all of these requirements. Vehicles are modeled as physical obstacles affecting the V2V communication. The proposed model accounts for vehicles as three-dimensional obstacles and takes into account their impact on the LOS obstruction, received signal power, and the packet reception rate. We utilize two real world highway datasets collected via stereoscopic aerial photography to test our proposed model, and we confirm the importance of modeling the effects of obstructing vehicles through experimental measurements. Our results show considerable obstruction of LOS due to vehicles. By obstructing the LOS, vehicles induce significant attenuation and packet loss. The algorithm behind the proposed model allows for computationally efficient implementation in VANET simulators. It is also shown that by modeling the vehicles as obstacles, significant realism can be added to existing simulators with clear implications on the design of upper layer protocols.

A survey and comparative study of simulators for vehicular ad hoc networks (VANETs)

Abstract: Wireless communication technologies have now greatly impact our daily lives. From indoor wireless LANs to outdoor cellular mobile networks, wireless technologies have benefited billions of users around the globe. The era of vehicular ad hoc networks (VANETs) is now evolving, gaining attention and momentum. Researchers and developers have built VANET simulation software to allow the study and evaluation of various media access, routing, and emergency warning protocols. VANET simulation is fundamentally different from MANETs (mobile ad hoc networks) simulation because in VANETs, vehicular environment imposes new issues and requirements, such as constrained road topology, multi-path fading and roadside obstacles, traffic flow models, trip models, varying vehicular speed and mobility, traffic lights, traffic congestion, drivers' behavior, etc. Currently, there are VANET mobility generators, network simulators, and VANET simulators. This paper presents a comprehensive study and comparisons of the various publicly available VANET simulation software and their components. In particular, we contrast their software characteristics, graphical user interface (GUI), popularity, ease of use, input requirements, output visualization capability, accuracy of simulation, etc. Finally, while each of the studied simulators provides a good simulation environment for VANETs, refinements and further contributions are needed before they can be widely used by the research community. Copyright © 2009 John Wiley & Sons, Ltd.

ABAKA: An Anonymous Batch Authenticated and Key Agreement Scheme for Value-Added Services in Vehicular Ad Hoc Networks

Abstract: In this paper, we introduce an anonymous batch authenticated and key agreement (ABAKA) scheme to authenticate multiple requests sent from different vehicles and establish different session keys for different vehicles at the same time. In vehicular ad hoc networks (VANETs), the speed of a vehicle is changed from 10 to 40 m/s (36-144 km/h); therefore, the need for efficient authentication is inevitable. Compared with the current key agreement scheme, ABAKA can efficiently authenticate multiple requests by one verification operation and negotiate a session key with each vehicle by one broadcast message. Elliptic curve cryptography is adopted to reduce the verification delay and transmission overhead. The security of ABAKA is based on the elliptic curve discrete logarithm problem, which is an unsolved NP-complete problem. To deal with the invalid request problem, which may cause the batch verification fail, a detection algorithm has been proposed. Moreover, we demonstrate the efficiency merits of ABAKA through performance evaluations in terms of verification delay, transmission overhead, and cost for rebatch verifications, respectively. Simulation results show that both the message delay and message loss rate of ABAKA are less than that of the existing elliptic curve digital signature algorithm (ECDSA)-based scheme.

Probabilistic Delay Control and Road Side Unit Placement for Vehicular Ad Hoc Networks with Disrupted Connectivity

Abstract: This paper studies the multihop packet delivery delay in a low density vehicular ad hoc network (VANET). We address a disrupted vehicle-to-infrastructure communication scenario, where an end-to-end path is unlikely to exist between a vehicle and the nearest road side unit (RSU). We present an analytical framework, which takes into account the randomness of vehicle data traffic and the statistical variation of the disrupted communication channel. Our framework employs the effective bandwidth theory and its dual, the effective capacity concept, in order to obtain the maximum distance between RSUs that stochastically limits the worst case packet delivery delay to a certain bound (i.e., allows only an arbitrarily small fraction of the packets received by the farthest vehicle from the RSU to exceed a required delay bound). Our study also investigates the effect of the vehicle density, transmission range, and speed difference between vehicles on the end-to-end packet delivery delay. Extensive simulation results validate our analytical framework.

Analysis of Information Dissemination in Vehicular Ad-Hoc Networks With Application to Cooperative Vehicle Safety Systems

Abstract: Cooperative vehicle safety systems (CVSSs) rely on vehicular ad-hoc networks (VANETs) for the delivery of critical vehicle tracking information. The wireless channel in such systems is shared by vehicles within the transmission range of each other. Due to the near-linear spatial distribution of vehicles in a highway scenario, the vehicular broadcast network is heavily affected by the hidden node interference phenomenon, which considerably limits its capacity. The performance of vehicle tracking application that is the basis for CVSS is therefore significantly affected by the performance of the underlying network. The two main parameters that affect the network condition and performance are the range and rate (frequency) of transmission of safety and tracking messages. In this paper, we analyze the effect of different choices of rate and range and present models that quantify network performance in terms of its ability to disseminate tracking information. Following a thorough analysis of the hidden node affected VANET, we show that channel occupancy or busy ratio can be used as a feedback measure that quantifies the success of information dissemination and, consequently, the CVSS, under different network conditions. These findings are used to design feedback control schemes for transmission range adaptation, which are robust to variations of road and network traffic.

CRP: A Routing Protocol for Cognitive Radio Ad Hoc Networks

Abstract: Cognitive radio (CR) technology enables the opportunistic use of the vacant licensed frequency bands, thereby improving the spectrum utilization. However, the CR operation must not interfere with the transmissions of the licensed or primary users (PUs), and this is generally achieved by incurring a trade-off in the CR network performance. In order to evaluate this trade-off, a distributed CR routing protocol for ad hoc networks (CRP) is proposed that makes the following contributions: (i) explicit protection for PU receivers that are generally not detected during spectrum sensing, (ii) allowing multiple classes of routes based on service differentiation in CR networks, and (iii) scalable, joint route-spectrum selection. A key novelty of CRP is the mapping of spectrum selection metrics, and local PU interference observations to a packet forwarding delay over the control channel. This allows the route formation undertaken over a control channel to capture the environmental and spectrum information for all the intermediate nodes, thereby reducing the computational overhead at the destination. Results reveal the importance of formulating the routing problem from the viewpoint of safeguarding the PU communication, which is a unique feature in CR networks.

MANET: Vulnerabilities, Challenges, Attacks, Application

Abstract: Mobile ad-hoc network (MANET) is one of the most promising fields for research and development of wireless network. As the popularity of mobile device and wireless networks significantly increased over the past years, wireless ad-hoc networks has now become one of the most vibrant and active field of communication and networks. Due to severe challenges, the special features of MANET bring this technology great opportunistic together. This paper describes the fundamental problems of ad hoc network by giving its related research background including the concept, features, status, and vulnerabilities of MANET. This paper presents an overview and the study of the routing protocols. Also include the several challenging issues, emerging application and the future trends of MANET.

Multi-Antenna Communication in Ad Hoc Networks: Achieving MIMO Gains with SIMO Transmission

Abstract: The benefit of multi-antenna receivers is investigated in wireless ad hoc networks, and the main finding is that network throughput can be made to scale linearly with the number of receive antennas N_r even if each transmitting node uses only a single antenna. This is in contrast to a large body of prior work in single-user, multiuser, and ad hoc wireless networks that have shown linear scaling is achievable when multiple receive and transmit antennas (i.e., MIMO transmission) are employed, but that throughput increases logarithmically or sublinearly with N_r when only a single transmit antenna (i.e., SIMO transmission) is used. The linear gain is achieved by using the receive degrees of freedom to simultaneously suppress interference and increase the power of the desired signal, and exploiting the subsequent performance benefit to increase the density of simultaneous transmissions instead of the transmission rate. This result is proven in the transmission capacity framework, which presumes single-hop transmissions in the presence of randomly located interferers, but it is also illustrated that the result holds under several relaxations of the model, including imperfect channel knowledge, multihop transmission, and regular networks (i.e., interferers are deterministically located on a grid).

Intersection-Based Geographical Routing Protocol for VANETs: A Proposal and Analysis

Abstract: This paper presents a class of routing protocols for vehicular ad hoc networks (VANETs) called the Intersection-based Geographical Routing Protocol (IGRP), which outperforms existing routing schemes in city environments. IGRP is based on an effective selection of road intersections through which a packet must pass to reach the gateway to the Internet. The selection is made in a way that guarantees, with high probability, network connectivity among the road intersections while satisfying quality-of-service (QoS) constraints on tolerable delay, bandwidth usage, and error rate. Geographical forwarding is used to transfer packets between any two intersections on the path, reducing the path's sensitivity to individual node movements. To achieve this, we mathematically formulate the QoS routing problem as a constrained optimization problem. Specifically, analytical expressions for the connectivity probability, end-to-end delay, hop count, and bit error rate (BER) of a route in a two-way road scenario are derived. Then, we propose a genetic algorithm to solve the optimization problem. Numerical and simulation results show that the proposed approach gives optimal or near-optimal solutions and significantly improves VANET performance when compared with several prominent routing protocols, such as greedy perimeter stateless routing (GPSR), greedy perimeter coordinator routing (GPCR), and optimized link-state routing (OLSR).

Modeling Broadcasting in IEEE 802.11p/WAVE Vehicular Networks

Abstract: IEEE 802.11p/WAVE (Wireless Access in Vehicular Environments) is an emerging family of standards intended to support wireless access in Vehicular Ad Hoc Networks (VANETs). Broadcasting of data and control packets is expected to be crucial in this environment. Both safety-related and non-safety applications rely on broadcasting for the exchange of data or status and advertisement messages. Most of the broadcasting traffic is designed to be delivered on a given frequency during the control channel (CCH) interval set by the WAVE draft standard. The rest of the time, vehicles switch over to one of available service channels (SCHs) for non-safety related data exchange. Although broadcasting in VANETs has been analytically studied, related works neither consider the WAVE channel switching nor its effects on the VANET performance. In this letter, a new analytical model is designed for evaluating the broadcasting performance on CCH in IEEE 802.11p/WAVE vehicular networks. This model explicitly accounts for the WAVE channel switching and computes packet delivery probability as a function of contention window size and number of vehicles.

A Distributed Key Management Framework with Cooperative Message Authentication in VANETs

Abstract: In this paper, we propose a distributed key management framework based on group signature to provision privacy in vehicular ad hoc networks (VANETs). Distributed key management is expected to facilitate the revocation of malicious vehicles, maintenance of the system, and heterogeneous security policies, compared with the centralized key management assumed by the existing group signature schemes. In our framework, each road side unit (RSU) acts as the key distributor for the group, where a new issue incurred is that the semi-trust RSUs may be compromised. Thus, we develop security protocols for the scheme which are able to detect compromised RSUs and their colluding malicious vehicles. Moreover, we address the issue of large computation overhead due to the group signature implementation. A practical cooperative message authentication protocol is thus proposed to alleviate the verification burden, where each vehicle just needs to verify a small amount of messages. Details of possible attacks and the corresponding solutions are discussed. We further develop a medium access control (MAC) layer analytical model and carry out NS2 simulations to examine the key distribution delay and missed detection ratio of malicious messages, with the proposed key management framework being implemented over 802.11 based VANETs.

Delay and capacity tradeoff analysis for motioncast

Abstract: In this paper, we define multicast for an ad hoc network through nodes' mobility as MotionCast and study the delay and capacity tradeoffs for it. Assuming nodes move according to an independently and identically distributed (i.i.d.) pattern and each desires to send packets to k distinctive destinations, we compare the delay and capacity in two transmission protocols: one uses 2-hop relay algorithm without redundancy; the other adopts the scheme of redundant packets transmissions to improve delay while at the expense of the capacity. In addition, we obtain the maximum capacity and the minimum delay under certain constraints. We find that the per-node delay and capacity for the 2-hop algorithm without redundancy are Θ(1/k) and Θ(n log k), respectively; for the 2-hop algorithm with redundancy, they are Ω(1/k√(n log k)) and Θ(√(n log k)), respectively. The capacity of the 2-hop relay algorithm without redundancy is better than the multicast capacity of static networks developed by Li [IEEE/ACM Trans. Netw., vol. 17, no. 3, pp. 950-961, Jun. 2009] as long as k is strictly less than n in an order sense, while when k=Θ(n), mobility does not increase capacity anymore. The ratio between delay and capacity satisfies delay/rate ≥ O(nk log k) for these two protocols, which are both smaller than that of directly extending the fundamental tradeoff for unicast established by Neely and Modiano [IEEE Trans. Inf. Theory, vol. 51, no. 6, pp. 1917-1937, Jun. 2005] to multicast, i.e., delay/rate ≥ O(n k2). More importantly, we have proved that the fundamental delay-capacity tradeoff ratio for multicast is delay/rate ≥ O(n log k), which would guide us to design better routing schemes for multicast.

Mobile Ad Hoc Networks: Current Status and Future Trends

Abstract: Guiding readers through the basics of these rapidly emerging networks to more advanced concepts and future expectations, Mobile Ad hoc Networks: Current Status and Future Trends identifies and examines the most pressing research issues in Mobile Ad hoc Networks (MANETs). Containing the contributions of leading researchers, industry professionals, and academics, this forward-looking reference provides an authoritative perspective of the state of the art in MANETs. The book includes surveys of recent publications that investigate key areas of interest such as limited resources and the mobility ofmobile nodes. It considers routing, multicast, energy, security, channel assignment, and ensuring quality of service. Also suitable as a text for graduate students, the book is organized into three sections: Fundamentals of MANET Modeling and SimulationDescribes how MANETs operate and perform through simulations and models Communication Protocols of MANETsPresents cutting-edge research on key issues, including MAC layer issues and routing in high mobility Future Networks Inspired By MANETsTackles open research issues and emerging trends Illustrating the role MANETs are likely to play in future networks, this book supplies the foundation and insight you will need to make your own contributions to the field. It includes coverage of routing protocols, modeling and simulations tools, intelligent optimization techniques to multicriteria routing, security issues in FHAMIPv6, connecting moving smart objects to the Internet, underwater sensor networks, wireless mesh network architecture and protocols, adaptive routing provision using Bayesian inference, and adaptive flow control in transport layer using genetic algorithms.

A survey and challenges in routing and data dissemination in vehicular ad hoc networks

Abstract: In this paper, we survey recent results in vehicular ad hoc networks (VANETs) data dissemination. We describe methods proposed to enforce dissemination scope such as geocast/broadcast and multicast. A growing category consisting of methods designed to achieve disruption tolerance in vehicular networks is presented. We describe the key ideas of representative technologies in each category. In addition, we consider location service and security issues that are crucial for data dissemination in VANET. We conclude by sharing our thoughts on further challenges. Copyright © 2009 John Wiley & Sons, Ltd.

VeRA - Version Number and Rank Authentication in RPL

Abstract: Designing a routing protocol for large low-power and lossy networks (LLNs), consisting of thousands of constrained nodes and unreliable links, presents new challenges. The IPv6 Routing Protocol for Low-power and Lossy Networks (RPL), have been developed by the IETF ROLL Working Group as a preferred routing protocol to provide IPv6 routing functionality in LLNs. RPL provides path diversity by building and maintaining directed acyclic graphs (DAG) rooted at one (or more) gateway. However, an adversary that impersonates a gateway or has compromised one of the nodes close to the gateway can divert a large part of network traffic forward itself and/or exhaust the nodes' batteries. Therefore in RPL, special security care must be taken when the Destination Oriented Directed Acyclic Graph (DODAG) root is updating the Version Number by which reconstruction of the routing topology can be initiated. The same care also must be taken to prevent an internal attacker (compromised DODAG node) to publish decreased Rank value, which causes a large part of the DODAG to connect to the DODAG root via the attacker and give it the ability to eavesdrop a large part of the network traffic forward itself. Unfortunately, the currently available security services in RPL will not protect against a compromised internal node that can construct and disseminate fake messages. In this paper, a new security service is described that prevents any misbehaving node from illegitimately increasing the Version Number and compromise illegitimate decreased Rank values.

Traffic information systems: efficient message dissemination via adaptive beaconing

Abstract: Traffic information systems are one of the key non-safety application areas of vehicular ad hoc networks. As such, TIS are much less delay sensitive than safety applications, which have recently attracted a lot of attention in VANET research. We propose a new message dissemination protocol, Adaptive Traffic Beacon (ATB), which is fully distributed and uses adaptive beaconing based on two key metrics: message utility and channel quality. It is shown that adaptive beaconing leads to much broader dissemination of messages (in terms of penetration rate) than flooding-based approaches, albeit at a slower rate. Adaptive beaconing thus seems to be much more suitable for TIS than flooding-based protocols.

Multipath optimized link state routing for mobile ad hoc networks

Abstract: Multipath routing protocols for Mobile Ad hoc NETwork (MANET) address the problem of scalability, security (confidentiality and integrity), lifetime of networks, instability of wireless transmissions, and their adaptation to applications. Our protocol, called MultiPath OLSR (MP-OLSR), is a multipath routing protocol based on OLSR [1]. The Multipath Dijkstra Algorithm is proposed to obtain multiple paths. The algorithm gains great flexibility and extensibility by employing different link metrics and cost functions. In addition, route recovery and loop detection are implemented in MP-OLSR in order to improve quality of service regarding OLSR. The backward compatibility with OLSR based on IP source routing is also studied. Simulation based on Qualnet simulator is performed in different scenarios. A testbed is also set up to validate the protocol in real world. The results reveal that MP-OLSR is suitable for mobile, large and dense networks with large traffic, and could satisfy critical multimedia applications with high on time constraints.

On the Effectiveness of an Opportunistic Traffic Management System for Vehicular Networks

Abstract: Road congestion results in a huge waste of time and productivity for millions of people. A possible way to deal with this problem is to have transportation authorities distribute traffic information to drivers, which, in turn, can decide (or be aided by a navigator) to route around congested areas. Such traffic information can be gathered by relying on static sensors placed at specific road locations (e.g., induction loops and video cameras) or by having single vehicles report their location, speed, and travel time. While the former approach has been widely exploited, the latter has come about only more recently; consequently, its potential is less understood. For this reason, in this paper, we study a realistic test case that allows the evaluation of the effectiveness of such a solution. As part of this process, (a) we designed a system that allows vehicles to crowd-source traffic information in an ad hoc manner, allowing them to dynamically reroute based on individually collected traffic information; (b) we implemented a realistic network-mobility simulator that allowed us to evaluate such a model; and (c) we performed a case study that evaluates whether such a decentralized system can help drivers to minimize trip times, which is the main focus of this paper. This study is based on traffic survey data from Portland, OR, and our results indicate that such navigation systems can indeed greatly improve traffic flow. Finally, to test the feasibility of our approach, we implemented our system and ran some real experiments at UCLA's C-Vet test bed.

Overview of Security Issues in Vehicular Ad-hoc Networks

Abstract: Vehicular ad-hoc networks (VANETs) are a promising communication scenario. Several new applications are envisioned, which will improve traffic management and safety. Nevertheless, those applications have stringent security requirements, as they affect road traffic safety. Moreover, VANETs face several security threats. As VANETs present some unique features (e.g. high mobility of nodes, geographic extension, etc.) traditional security mechanisms are not always suitable. Because of that, a plethora of research contributions have been presented so far. This chapter aims to describe and analyze the most representative VANET security developments.

The Wireless Control Network: A New Approach for Control Over Networks

Abstract: We present a method to stabilize a plant with a network of resource constrained wireless nodes. As opposed to traditional networked control schemes where the nodes simply route information to and from a dedicated controller (perhaps performing some encoding along the way), our approach treats the network itself as the controller. Specifically, we formulate a strategy for each node in the network to follow, where at each time-step, each node updates its internal state to be a linear combination of the states of the nodes in its neighborhood. We show that this causes the entire network to behave as a linear dynamical system, with sparsity constraints imposed by the network topology. We provide a numerical design procedure to determine appropriate linear combinations to be applied by each node so that the transmissions of the nodes closest to the actuators will stabilize the plant. We also show how our design procedure can be modified to maintain mean square stability under packet drops in the network, and present a distributed scheme that can handle node failures while preserving stability. We call this architecture a Wireless Control Network, and show that it introduces very low computational and communication overhead to the nodes in the network, allows the use of simple transmission scheduling algorithms, and enables compositional design (where the existing wireless control infrastructure can be easily extended to handle new plants that are brought online in the vicinity of the network).

Survey of media access control protocols for vehicular ad hoc networks

Abstract: Recent advances in various wireless communication technologies and the emergence of computationally rich vehicles are pushing vehicular ad hoc network (VANET) research to the forefront in academia and industry. A lot of research results have been published in various areas (such as routing, broadcasting, security and others) of VANET in the last decade covering both vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) scenarios. One specific area of VANET that still faces significant challenges is the design of reliable and robust media access control (MAC) protocols for V2V communications. The authors present a survey of V2V MAC methods (including various VANET standards) that have been proposed for VANETs over the last few years. The authors also focus on the benefits and limitations of the proposed MAC techniques as well as their ease of implementation in practice and future deployment. In addition some of the challenges that still need to be addressed to enable the implementation of highly efficient and high performance MAC protocols for V2V communications are discussed. Finally, some innovative solutions that can be developed to address these challenges are proposed.

On power and throughput tradeoffs of WiFi and Bluetooth in smartphones

Abstract: This paper describes a combined power and throughput performance study of WiFi and Bluetooth usage in smartphones. The study reveals several interesting phenomena and tradeoffs. The conclusions from this study suggest preferred usage patterns, as well as operative suggestions for researchers and smartphone developers.

A Probabilistic Analysis of Link Duration in Vehicular Ad Hoc Networks

Abstract: The past decade has witnessed a phenomenal market penetration of wireless communications and a steady increase in the number of mobile users. Unlike wired networks, where communication links are inherently stable, in wireless networks, the lifetime of a link is a random variable whose probability distribution depends on mobility, transmission range, and various impairments of radio communications. Because of the very dynamic nature of Vehicular Ad hoc NETworks (VANETs) and the short transmission range mandated by the Federal Communications Commission (FCC), individual communication links come into existence and vanish unpredictably, making the task of establishing and maintaining routing paths between fast-moving vehicles very challenging. The main contribution of this work is to investigate the probability distribution of the lifetime of individual links in a VANET under the combined assumptions of a realistic radio transmission model and a realistic probability distribution model of intervehicle headway distance. Our analytical results were validated and confirmed by extensive simulation.