Coverage Of Roadside Units Research Articles

A novel message authentication method for VANET without RSU

Purpose Riding on the wave of intelligent transportation systems, the vehicular ad hoc network (VANET) is becoming a popular research topic. VANET is designed to build an environment where the vehicles can exchange information about the traffic conditions or vehicle situation to help the vehicles avoid traffic accidents or traffic jams. In order to keep the privacy of vehicles, the vehicles must be anonymous and the routing must be untraceable while still being able to be verified as legal entities. The paper aims to discuss these issues. Design/methodology/approach The exchanged messages must be authenticated to be genuine and verified that they were sent by a legal vehicle. The vehicles also can mutually trust and communicate confidentially. In VANETs, road-side units (RSUs) are installed to help the vehicles to obtain message authentication or communicate confidentially. However, the coverage of RSUs is limited due to the high cost of wide area installation. Therefore the vehicles must be able to obtain message authentication by themselves – without an RSU. Findings The authors take the concept of random key pre-distribution used in wireless sensor networks, modify it into a random secret pre-distribution, and integrate it with identity-based cryptography to make anonymous message authentication and private communication easier and safer. The authors construct a two-tier structure. The tier 1, trust authority, assigns n anonymous identities and embeds n secrets into these identities to be the private secret keys for the tier 2, registered vehicles. At any time, the vehicles can randomly choose one of n anonymous identities to obtain message authentication or communicate confidentially with other vehicles. Originality/value The processes of building neighbor set, setting pairing value, and message authenticating are proposed in this paper. The proposed method can protect against the attacks of compromising, masquerading, forging, and replying, and can also achieve the security requirements of VANET in message authentication, confidential communication, anonymity, and un-traceability. The performance of the proposed method is superior to the related works.

ECDS: Efficient collaborative downloading scheme for popular content distribution in urban vehicular networks

The recent development of the Vehicular Ad-hoc Networks (VANETs) has motivated an increasing interest in in-vehicle consumption, and hence, the Popular Content Distribution (PCD) has become a heated issue. Compared with PCD solutions based on the widely-used cellular networks and Dedicated Short Range Communications (DSRC), solutions based on Collaborative Downloading (CD) are more economical and efficient. Due to the limited bandwidth, the On-Board Units (OBUs) passing through a Road Side Unit (RSU) can only download a portion of the popular content. To get over that drawback and to effect a collaborative downloading, a P2P network should be constructed among the OBUs which fall out of the RSUs coverage. In this paper, we address the efficient collaborative downloading scheme (ECDS) for PCD in urban traffic scenarios. To adapt to the rapid-changing characteristics of the VANET topology, a new cell-based clustering scheme is proposed, which greatly simplifies the modeling. Besides a strategy of inter-cluster Relay Selection is proposed to construct a pear-to-pear (P2P) network of scale-free property, which will help enhancing the information spread. Furthermore, another inter-cluster strategy of generation selection is to be collaborated to accelerate the dissemination process in the P2P network. The comparison experiments to two up-to-date collaborative PCD protocols demonstrate the high performance of the proposed scheme, i.e. ECDS.

The Role of Parked Cars in Content Downloading for Vehicular Networks

When it comes to content access using intervehicle communications (IVC), data will mostly flow through roadside units (RSUs) that deployed in our cities. Unfortunately, the RSU coverage is expected to be rather scattered. Instead of relying on RSUs only, this paper investigates the possibility of exploiting parked vehicles to extend the RSU service coverage. Our approach leverages optimization models aiming at maximizing the freshness of content that downloaders retrieve, the efficiency in the utilization of radio resources, and the fairness in exploiting the energy resources of parked vehicles. The latter is constrained to not excessively drain parked vehicle batteries. Our approach provides an estimate of the system performance, even in those cases where users may only be willing to lease a limited amount of their battery capacity to extend RSU coverage. Our optimization-based results are validated by comparing them against ns-3 simulations. Performance evaluation highlights that the use of parked vehicles enhances the efficiency of the content downloading process by 25%-35% and can offload more than half the data traffic from RSUs with respect to the case where only moving cars are used as relays. Such gains in performance come at a small cost in terms of battery utilization for the parked vehicles, and they are magnified when a backbone of parked vehicles can be formed.

Broadcast‐based data delivery strategy for V2I multihop vehicular networks

A new strategy to reduce data delivery delay for vehicle-to-infrastructure (V2I) communication systems with multiple stationary roadside units (RSUs) is proposed. With the proposed strategy, the data delivery is accomplished through vehicles possessing identical packets received via broadcasting from an RSU, and the group of the packet-possessing vehicles is refreshed at each RSU hop. Numerical results show that the proposed strategy reduces the data delivery delay compared with an existing strategy and does so more significantly for a middle-range traffic density. In addition, the proposed strategy has better performance as the broadcast duration and the RSU's coverage area increase.

Secure Cooperative Data Downloading in Vehicular Ad Hoc Networks

In this paper, we propose a secure cooperative data downloading framework for paid services in vehicular ad hoc networks (VANETs). In our framework, vehicles download data when they pass by a road side unit (RSU) and then share the data after they travel out of the RSU's coverage. A fundamental issue of cooperative data downloading is how vehicles effectively share data with each other. We develop an application layer data sharing protocol which coordinates the vehicles to relay data for sharing according to their positions. Such coordinated sharing can avoid collisions in the medium access control (MAC) layer and the hidden terminal issue in multi-hop transmissions. A salient feature of the proposed sharing protocol is that it can guarantee the receipt of the requested data file for each applicant vehicle passing a road side unit. Moreover, we also address security and privacy issues in the process of data downloading and sharing, ensuring applicants' exclusive access to the applied data and privacy of the vehicles involved in the application. We carry out NS2 simulations to thoroughly examine the performance of the proposed cooperative downloading protocol implemented over an 802.11p based VANETs.

On the performances of forwarding multihop unicast traffic in WBSS-based 802.11(p)/1609 networks

The IEEE 802.11(p)/1609 network is a promising candidate for future vehicular communication networks. In this new network, the operation of a new Wave Basic Service set (WBSS) is defined for vehicular environments. Due to the deployment cost consideration, roadside units (RSUs) in such networks are usually installed only at hot spots and intersections, causing the service coverage of RSUs to be discontinuous. To overcome this problem, multihop data forwarding among vehicles can be used to extend the service coverage of RSUs. The multihop geocasting problem has been studied and addressed in our previous work [1], where we proposed a receiver-centric WBSS geocasting scheme to increase multihop geocasting performances in WBSS-based networks. However, multihop unicasting, a more common facility in many network applications and services, was not dealt with in [1]. In this paper, we propose a new Receiver-centric WBSS Forwarding Scheme for Unicast traffic (called RWFS-U), which uses a prioritized receiver-centric WBSS creation design to efficiently support unicast data forwarding in WBSS-based networks. Extensive performance evaluations using both analyses and simulations are presented to understand the effects of the designs of WBSS forwarding schemes on the goodputs of end-to-end flows. Our results show that RWFS-U can significantly outperform the traditional sender-centric schemes on multihop unicasting in WBSS-based networks.

Simulating Operations Applications of Vehicle Infrastructure Integration

Vehicle infrastructure integration (VII) is receiving significant attention because of its potential to provide a wide range of benefits. However, to inform design, deployment, and operations decisions best, it will be necessary to evaluate potential VII-enabled applications fully. A research effort investigated a VII-enabled traffic monitoring application. First, the VII simulation environment developed to support the research was described. Next, traffic monitoring coverage as a function of VII roadside unit (RSU) configuration (i.e., number of units and placement) was investigated. The results of the study indicated that, on the basis of current guidance in the VII architecture, roughly 55% of the sections in the network would be within the direct range of an RSU. Finally, the accuracy and the coverage of monitored links were evaluated. The results of the analysis demonstrated that only 35% of RSU-covered sections were monitored at 1% penetration rates, but the combined effect of direct RSU coverage and indirect coverage through vehicle storage was quite high (around 60%) for a heavily traveled urban network. The results also illustrated that at low levels of vehicles equipped with VII (1% to 10%), the mean absolute error of speed estimation was about 4 mph. However, as the penetration rate increase to 30%, the error dropped to even lower values, roughly 2.5 mph. Finally, it was found that with a default buffer value of 30 snapshots of vehicle storage, the greatest error in indirectly covered sections for mean freeway section speed was 6 mph at 1% penetration rate.