Cognitive radio network in vehicular ad hoc network (VANET): a survey

Cognitive radio network and vehicular ad hoc network (VANET) are recent emerging concepts in wireless networking. Cognitive radio network obtains knowledge of its operational geographical environment to manage sharing of spectrum between primary and secondary users, while VANET shares emergency safety messages among vehicles to ensure safety of users on the road. Cognitive radio network is employed in VANET to ensure the efficient use of spectrum, as well as to support VANET’s deployment. Random increase and decrease of spectrum users, unpredictable nature of VANET, high mobility, varying interference, security, packet scheduling, and priority assignment are the challenges encountered in a typical cognitive VANET environment. This paper provides survey and critical analysis on different challenges of cognitive radio VANET, with discussion on the open issues, challenges, and performance metrics for different cognitive radio VANET applications

Cognitive radio network in vehicular ad hoc network (VANET): a survey

Cognitive radio network and vehicular ad hoc network (VANET) are recent emerging concepts in wireless networking. Cognitive radio network obtains knowledge of its operational geographical environment to manage sharing of spectrum between primary and secondary users, while VANET shares emergency safety messages among vehicles to ensure safety of users on the road. Cognitive radio network is employed in VANET to ensure the efficient use of spectrum, as well as to support VANET’s deployment. Random increase and decrease of spectrum users, unpredictable nature of VANET, high mobility, varying interference, security, packet scheduling, and priority assignment are the challenges encountered in a typical cognitive VANET environment. This paper provides survey and critical analysis on different challenges of cognitive radio VANET, with discussion on the open issues, challenges, and performance metrics for different cognitive radio VANET applications

Cognitive radio network in vehicular ad hoc network (VANET): a survey

Cognitive radio network and vehicular ad hoc network (VANET) are recent emerging concepts in wireless networking. Cognitive radio network obtains knowledge of its operational geographical environment to manage sharing of spectrum between primary and secondary users, while VANET shares emergency safety messages among vehicles to ensure safety of users on the road. Cognitive radio network is employed in VANET to ensure the efficient use of spectrum, as well as to support VANET’s deployment. Random increase and decrease of spectrum users, unpredictable nature of VANET, high mobility, varying interference, security, packet scheduling, and priority assignment are the challenges encountered in a typical cognitive VANET environment. This paper provides survey and critical analysis on different challenges of cognitive radio VANET, with discussion on the open issues, challenges, and performance metrics for different cognitive radio VANET applications

PrivHab : A privacy preserving georouting protocol based on a multiagent system for podcast distribution on disconnected areas

Altres ajuts: Universitat Autònoma de Barcelona 472-03-01/2012We present PrivHab, a privacy preserving georouting protocol that improves multiagent decision-making. PrivHab learns the mobility habits of the nodes of the network. Then, it uses this information to dynamically select to route an agent carrying a piece of data to reach its destination. PrivHab makes use of cryptographic techniques from secure multi-party computation to make the decisions while preserving nodes' privacy. PrivHab uses a waypoint-based routing that achieves a high performance and low overhead in rugged terrain areas that are plenty of physical obstacles. The store-carry-and-forward approach used is combined with mobile agents that provide intelligence, and it is designed to operate in areas that lack network infrastructure. We have evaluated PrivHab under the scope of a realistic podcast distribution application in remote rural areas, where these programs have to be recorded into a physical format and distributed to the local radio stations. The usage of PrivHab aims to reduce this spending of resources. The PrivHab protocol is compared with a set of well-known delay-tolerant routing algorithms and shown to outperform them

DESIGN OF EFFICIENT IN-NETWORK DATA PROCESSING AND DISSEMINATION FOR VANETS

By providing vehicle-to-vehicle and vehicle-to-infrastructure wireless communications, vehicular ad hoc networks (VANETs), also known as the “networks on wheels”, can greatly enhance traffic safety, traffic efficiency and driving experience for intelligent transportation system (ITS). However, the unique features of VANETs, such as high mobility and uneven distribution of vehicular nodes, impose critical challenges of high efficiency and reliability for the implementation of VANETs. This dissertation is motivated by the great application potentials of VANETs in the design of efficient in-network data processing and dissemination. Considering the significance of message aggregation, data dissemination and data collection, this dissertation research targets at enhancing the traffic safety and traffic efficiency, as well as developing novel commercial applications, based on VANETs, following four aspects: 1) accurate and efficient message aggregation to detect on-road safety relevant events, 2) reliable data dissemination to reliably notify remote vehicles, 3) efficient and reliable spatial data collection from vehicular sensors, and 4) novel promising applications to exploit the commercial potentials of VANETs. Specifically, to enable cooperative detection of safety relevant events on the roads, the structure-less message aggregation (SLMA) scheme is proposed to improve communication efficiency and message accuracy. The scheme of relative position based message dissemination (RPB-MD) is proposed to reliably and efficiently disseminate messages to all intended vehicles in the zone-of-relevance in varying traffic density. Due to numerous vehicular sensor data available based on VANETs, the scheme of compressive sampling based data collection (CS-DC) is proposed to efficiently collect the spatial relevance data in a large scale, especially in the dense traffic. In addition, with novel and efficient solutions proposed for the application specific issues of data dissemination and data collection, several appealing value-added applications for VANETs are developed to exploit the commercial potentials of VANETs, namely general purpose automatic survey (GPAS), VANET-based ambient ad dissemination (VAAD) and VANET based vehicle performance monitoring and analysis (VehicleView). Thus, by improving the efficiency and reliability in in-network data processing and dissemination, including message aggregation, data dissemination and data collection, together with the development of novel promising applications, this dissertation will help push VANETs further to the stage of massive deployment

Routing protocol for V2X communications for Urban VANETs

Intelligent Transportation Systems (ITSs) have been attracting tremendous attention in both academia and industry due to emerging applications that pave the way towards safer enjoyable journeys and inclusive digital partnerships. Undoubtedly, these ITS applications will demand robust routing protocols that not only focus on Inter-Vehicle Communications but also on providing fast, reliable, and secure access to the infrastructure. This thesis aims mainly to introduce the challenges of data packets routing through urban environment using the help of infrastructure. Broadcasting transmission is an essential operational technique that serves a broad range of applications which demand different restrictive QoS provisioning levels. Although broadcast communication has been investigated widely in highway vehicular networks, it is undoubtedly still a challenge in the urban environment due to the obstacles, such as high buildings. In this thesis, the Road-Topology based Broadcast Protocol (RTBP) is proposed, a distance and contention-based forwarding scheme suitable for both urban and highway vehicular environments. RTBP aims at assigning the highest forwarding priority to a vehicle, called a mobile repeater, having the greatest capability to send the packet in multiple directions. In this way, RTBP effectively reduces the number of competing vehicles and minimises the number of hops required to retransmit the broadcast packets around the intersections to cover the targeted area. By investigating the RTBP under realistic urban scenarios against well-known broadcast protocols, eMDR and TAF, that are dedicated to retransmitting the packets around intersections, the results showed the superiority of the RTBP in delivering the most critical warning information for 90% of vehicles with significantly lower delay of 58% and 70% compared to eMDR and TAF. The validation of this performance was clear when the increase in the number of vehicles. Secondly, a Fast and Reliable Hybrid routing (FRHR) protocol is introduced for efficient infrastructure access which is capable of handling efficient vehicle to vehicle communications. Interface to infrastructure is provided by carefully placed RoadSide Units (RSUs) which broadcast beacons in a multi-hop fashion in constrained areas. This enables vehicles proactively to maintain fresh minimum-delay routes to other RSUs while reactively discovering routes to nearby vehicles. The proposed protocol utilizes RSUs connected to the wired backbone network to relay packets toward remote vehicles. A vehicle selects an RSU to register with according to the expected mean delay instead of the device’s remoteness. The FRHR performance is evaluated against established infrastructure routing protocols, Trafroute, IGSR and RBVT-R that are dedicated to for urban environment, the results showed an improvement of 20% to 33% in terms of packet delivery ratio and lower latency particularly in sparse networks due to its rapid response to changes in network connectivity. Thirdly, focusing on increasing FRHR’s capability to provide more stable and durable routes to support the QoS requirements of expected wide-range ITS applications on the urban environment, a new route selection mechanism is introduced, aiming at selecting highly connected crossroads. The new protocol is called, Stable Infrastructure Routing Protocol (SIRP). Intensive simulation results showed that SIRP offers low end-to-end delay and high delivery ratio with varying traffic density, while resolving the problem of frequent link failures

Security in Delay Tolerant Networks

Delay- and Disruption-tolerant wireless networks (DTN), or opportunistic networks, represent a class of networks where continuous end-to-end connectivity may not be possible. DTN is a well recognized area in networking research and has attracted extensive attentions from both network designers and application developers. Applications of this emergent communication paradigm are wide ranging and include sensor networks using scheduled intermittent connectivity, vehicular DTNs for dissemination of location-dependent information (e.g., local ads, traffic reports, parking information, etc.), pocket-switched networks to allow humans to communicate without network infrastructure, and underwater acoustic networks with moderate delays and frequent interruptions due to environmental factors, etc. Security is one of the main barriers to wide-scale deployment of DTNs, but has gained little attention so far. On the one hand, similar to traditional mobile ad hoc networks, the open channel and multi-hop transmission have made DTNs vulnerable to various security threats, such as message modification/injection attack or unauthorized access and utilization of DTN resources. On the other hand, the unique security characteristics of DTNs including: long round-trip delay, frequent disconnectivity, fragmentation, opportunistic routing as well as limited computational and storage capability, make the existing security protocols designed for the conventional ad hoc networks unsuitable for DTNs. Therefore, a series of new security protocols are highly desired to meet stringent security and efficiency requirements for securing DTNs. In this research, we focus on three fundamental security issues in DTNs: efficient DTN message (or bundle) authentication, which is a critical security service for DTN security; incentive issue, which targets at stimulating selfish nodes to forward data for others; and certificate revocation issue, which is an important part of public key management and serves the foundation of any DTN security protocols. We have made the following contributions: First of all, the unique ``store-carry-and-forward'' transmission characteristic of DTNs implies that bundles from distinct/common senders may opportunistically be buffered at some common intermediate nodes. Such a ``buffering'' characteristic distinguishes DTN from any other traditional wireless networks, for which intermediate cache is not supported. To exploit such buffering opportunities, we propose an Opportunistic Batch Bundle Authentication Scheme (OBBA) to dramatically reduce the bundle authentication cost by seamlessly integrating identity-based batch signatures and Merkle tree techniques. Secondly, we propose a secure multi-layer credit based incentive scheme to stimulate bundle forwarding cooperation among DTNs nodes. The proposed scheme can be implemented in a fully distributed manner to thwart various attacks without relying on any tamper-proof hardware. In addition, we introduce several efficiency-optimization techniques to improve the overall efficiency by exploiting the unique characteristics of DTNs. Lastly, we propose a storage-efficient public key certificate validation method. Our proposed scheme exploits the opportunistic propagation to transmit Certificate Revocation List (CRL) list while taking advantage of bloom filter technique to reduce the required buffer size. We also discuss how to take advantage of cooperative checking to minimize false positive rate and storage consumption. For each research issue, detailed simulation results in terms of computational time, transmission overhead and power consumption, are given to validate the efficiency and effectiveness of the proposed security solutions