Adaptive Channel Equalizer for Wireless Access in Vehicular Environments

This research addresses reliability issues of safety applications in Intelligent Transportation Systems (ITS) that use Dedicated Short Range Communication (DSRC) in Wireless Access in Vehicular Environments (WAVE) systems. Reliability of such applications is affected not only by the usual environmental effects of wireless communication, but also potentially by malicious act. The case of constant and random jamming and their impact on safety applications are investigated under consideration of the data rates used. It is shown that the most important message, the Basic Safety Message (BSM), which is transmitted on a dedicated safety channel can be jammed, resulting in safety application failure. To mitigate against jamming a communication scheme based on redundant channel is used that utilizes channels with higher power ratings for communicating data with BSM-equivalent content, while not deviating from existing standards. The impact of channel and message redundancy for different data rates is investigated. Considering the two jammer types, it is shown that the introduction of redundancy overcomes the impact of jamming attacks. Furthermore it is demonstrated that application reliability increases inverse to the data rates of the channels. Analysis shows that DSRC safety applications that use redundant communication can overcome jamming attacks if data rates of 3Mbps and 6Mbps are used, while 12Mbps communication is not advisable.

The research of vehicular networks has been studied for many years. In actual life, there are a few implementations of V2X communication system, majority of them are extremely expensive. Most importantly, detailed insight implementation procedure hasn't been provided for researches. In this paper, an efficient V2X communication system based on the IEEE 802.11p/1609.X protocol stack, also known as the Wireless Access in Vehicular Environment (WAVE) standard has been designed. In this system, a Dedicated Short Range Communication (DSRC) unit using low-cost and commercial hardware which can support the vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications is developed. Some specific driver adjustments based on the IEEE 802.11a driver are taken to assure compliance with the IEEE 802.11p protocol. Besides, the development of networking layer protocol is accomplished based on IEEE 1609.3. Furthermore, three safety applications and a performance evaluation subsystem have been developed on this platform. The subsystem can test the comprehensive performance of the communication unit in terms of Packet Loss Rate (PLR), throughput and end-to-end delay. Meanwhile enormous experiments are conducted to evaluate the performance of the communication prototype and different scenarios were designed to validate the practical function of the safety applications.

Dedicated Short Range Communications (DSRC) is a wireless communication standard intended for high speed secure communication between vehicles and the infrastructure. In order to overcome the limitations that vehicular environment imposes such as high mobility, IEEE published the 802.11p amendment widely known as Wireless Access in Vehicular Environment (WAVE). To the best of our knowledge, most of the WAVE stack implementations and studies that are carried out till now are simulator based. This paper majorly focuses on the implementation of IEEE 1609 WAVE /DSRC stack on a Linux based system that forms the backbone of vehicular communication. It dives deep into the changes and the development of new modules that have to be made in Linux kernel to cater the need for vehicular communication. We also discuss in brief about the various challenges faced and design decisions that were made in this process. Finally, we conclude by depicting the performance of our developed stack in comparison with commercially available stack in terms of packet losses.

<div class="section abstract"> <div class="htmlview paragraph">This SAE Standard specifies a message set, and its data frames and data elements specifically for use by applications intended to utilize the 5.9 GHz Dedicated Short Range Communications for Wireless Access in Vehicular Environments (DSRC/WAVE, referenced in this document simply as “DSRC”), communications systems. Although the scope of this Standard is focused on DSRC, this message set, and its data frames and data elements have been designed, to the extent possible, to also be of potential use for applications that may be deployed in conjunction with other wireless communications technologies. This Standard therefore specifies the definitive message structure and provides sufficient background information to allow readers to properly interpret the message definitions from the point of view of an application developer implementing the messages according to the DSRC Standards.</div> </div>

Vehicular Ad-Hoc Networks (VANETs) play a significant role in Intelligent Transportation Systems (ITS). The vehicles exchange awareness and safety information with surrounding vehicles using IEEE 802.11p Dedicated Short Range Communications (DSRC) and IEEE 1609 Wireless Access in Vehicular Environment (WAVE)-based short-range communication networks in 5.9 GHz band. These safety messages include periodic beacon messages and event driven emergency messages that are shared in Control Channel (CCH). By collecting these messages and applying clustering we can facilitate new applications like network congestion control, traffic control etc. The partitioning-based clustering methods like the k-means, the Partitioning Around Medoids (PAM) are well known in data science. This paper focuses on understanding the message clustering intuitively. The clustering quality is measured using silhouette plot and average silhouette width. The simulation is carried out in OMNeT++ and SUMO-based Veins framework. A simple approach using a package called RInside is explored for fast prototyping of machine learning algorithms in OMNeT++ simulations.

Results of system simulations on link level for vehicle-to-vehicle (v2v) communications are presented in this paper. The corresponding system model complies with the IEEE802.11a wireless LAN standard, which is expected to play a major role in future inter-vehicle communications (IVC) systems. Only the physical (PHY) layer is considered for the simulations. A realistic channel model is integrated in the system model. Different characteristic road traffic scenarios, such as a motorway and an urban road are investigated. Both, line-of-sight (LOS) and non-line-of-sight (NLOS) situations are taken into account. For the simulations only the link between two vehicles is considered. Interference resulting from other vehicles is neglected. The results are characteristic curves of the bit error rate (BER) and packet error rate (PER) over the signal to noise ratio (SNR) at the receiver. I. INTRODUCTION The road traffic density is continuously increasing. The re- sulting large number of vehicles on the streets leads to congestion and accidents, which cause delays, costs, injuries and sometimes death. It is therefore a challenging task to cope with all the upcoming traffic. A necessary step to solve the problem is to provide the driver in time with specific route dependent information. This includes mobility-relevant information (e.g. the actual traffic conditions on the whole route) as well as safety-relevant information (e.g. detailed information about the road and traffic conditions in the vicinity of the vehicle). Thereby, the primary goal is to improve the traffic flow, avoid accidents and shorten journey lengths. Moreover, the increasing demand for mobile computing will have the future automobiles being equipped with high data rate access to the internet. Various multimedia applications, such as video on demand, games, email, etc. will be available. To provide automobiles with this large amount of informa- tion, inter-vehicle communications will be one necessary tool (1), (2). It is expected that in the future all vehicles on a road are able to communicate with each other and to share data. As the number of participants in such a dynamic communication scenario is fluctuating rapidly, IVC will be organised in an ad-hoc network manner (3). North American authorities allocated 75MHz of spectrum in the 5GHz band for dedicated short-range communications (DSRC). DSRC is expected to enable delivery of large amount of data to vehicles at short ranges via v2v and vehicle-to- roadside (v2r) wireless links (3). The Federal Communications Commission (FCC) report and order 03-324 is adopting licen- sing and service rules for the DSRC standard, especially focu- sed on v2v and v2r communication (4). Currently, the Ameri- can Society for Testing and Materials (ASTM) and the Institute of Electrical and Electronics Engineers (IEEE) are working on an evolution of the IEEE802.11a wireless LAN standard for v2v and v2r communications termed IEEE802.11p (Wireless Access in Vehicular Environments, WAVE) (5), (6). The PHY layer of IEEE802.11p will be similar to that of IEEE802.11a. Results of IVC link level simulations, which are performed on the basis of IEEE802.11a (7), are presented in this paper. For the investigations a base-band model of IEEE802.11a is implemented in the development environment System Studio (8). The model contains solely the PHY layer of the system. In order to get reasonable results a realistic model of the inter-vehicle transmission channel is used for the system simulations (9). Different characteristic road traffic scenarios, such as a motorway and an urban road are investigated. Both, LOS and NLOS situations are taken into account. For the simulations only the link between two vehicles is considered. Interference resulting form other vehicles is neglected. For each scenario the BER and PER over the SNR at the receiver are determined. The 6Mbit/s and 12Mbit/s transmission mode of IEEE802.11a are analysed. The channel model and the system model are described in the following two sections. Subsequently, the results of the simulations are presented.

Vehicular networks face a typical quandary in their requirement for communications that are at once secure and private. While the messages broadcast between vehicles and between vehicles and the supporting infrastructure must be authentic and non repudiable, they must also ensure the vehicle driver's anonymity. The Dedicated Short Range Communications (DSRC) framework's Wireless Access in Vehicular Environments (WAVE) application development architecture mandates the use of Public Key Infrastructure (PKI) mechanisms for securing messages, consequently compromising the driver's expectation of privacy. In this paper, we propose a WAVE-based protocol for the secure and anonymous propagation of vehicle safety broadcast messages. A hybrid key infrastructure approach is put forth which combines the use of a shared network authorization key for devices that require anonymity and PKI for devices that do not.

Modern vehicles are configured to exchange warning messages through IEEE 1609 Dedicated Short Range Communication (DSRC) over IEEE 802.11p Wireless Access in Vehicular Environment (WAVE). Essentially, these warning messages must associate an authentication factor such that the verifier authenticates the message origin via visual binding. Interestingly, the existing vehicle communication incorporates the message forward-ability as a requested feature for numerous applications. On the contrary, the vehicle security infrastructure is vulnerable to message forwarding i.e., Messages seem to originate from a malicious vehicle (due to non-detectable message relaying) instead of the actual message sender. We introduce the non forward-able authentication to avoid an adversary coalition attack scenario. These messages should be identifiable with respect to the immediate sender at every hop. We propose to utilize immediate optical response verification in association with the authenticated key exchange over radio channel. These optical responses are generated through hardware means, i.e., A certified Physically Unclonable Function (PUF) device embedded on the front and rear of the vehicle.

Vehicular ad hoc networks (VANETS) are simply a collection of onboard units (OBUs) and roadside units (RSUs) that communicate using dedicated short-range communications (DSRC) utilizing 75 Mhz in 5.9 GHz frequency band for wireless access in vehicular environment (WAVE). The frequency channel layout of WAVE has been divided into seven channels, with one channel for service safety applications and the remaining for service non-safety applications. The nature of the VANET environment being dynamic, it is most likely that packet forwarding over varied time intervals may be disconnected, causing network delays. In such a case the message containing information needs to be with the current vehicle until a new intelligent node becomes active. Extensive studies have been conducted on the propagation of messages in vehicular networks. Although conventional methods are mainly focused on similar traffic, in this only high, low-density traffic is considered. The intelligent mobile node structure in NS-3 has been designed in such a way as to support 802.11 MAC with a single channel. However, this intelligent mobile node is not appropriate for WAVE multi-channel operation.

Providing quality-of-service- (QoS-) guaranteed video on demand (VOD) services over wireless access in vehicular environments (WAVEs) is a challenge as WAVE adopts enhanced distributive channel access (EDCA), a contention-based channel access mechanism, for air interface access control. This paper proposes a selective downlink scheduling (SDS) algorithm to enhance the quality of VOD for WAVE networks. According to the importance of video decoding, video packets are categorized into high and low priorities. The categorized packets are put into different queues in roadside units (RSUs) to contend for transmission opportunities. Aiming to improve video playback quality and reduce video playback delay, the proposed SDS algorithm schedules video packets based on their importance, playback deadline, and their real-time parameters of receiving onboard units (OBUs), such as velocity and remaining dwelling time. The effectiveness of SDS algorithm is verified by simulations.

The exploration is built upon Delphi’s, Nissan’s, Cohda Wireless’ and Savari’s experiences in Asia, Europe and U.S.A. It describes and derives lessons from all four companies’ contributions in projects such as SMARTWAY in Japan, Drive C2X and in Europe, as well as the Connected Vehicle Safety Pilot in the U.S.A. All the above programs were implemented by means of the Dedicated Short Range Communication (DSRC) technology in the SHF spectrum based on the IEEE 802.11p/Wireless Access in Vehicular Environments (WAVE) standard. The study is supplemented with insights regarding complementary technologies such DSRC in the lower UHF frequency band (i.e. 700 MHz) as well as a V2X implementation through the 4G LTE (Long Term Evolution) cellular telecommunication technology. This paper addresses issues regarding the physical layer (PHY) of the DSRC system. The combination of the delay profile caused by multipath propagation along with the motion-based Doppler spread leads to time and frequency dispersion. This limits the number of bytes acceptable for reliable communication or requires a solution at the receiver end. The analysis of the Doppler spread shows that DSRC implemented at 700 MHz is more immune from data packet length issues as opposed to 5 GHz DSRC. On the other hand, 700 MHz DSRC exhibits a much longer delay spread. Thus, guard time interval specified in ASTM E2213-03 cannot be applied as is to 700 MHz DSRC. This paper refers to the German project CoCarX and the Japanese SKY for pedestrian for studying the feasibility a V2X system built on the 4G/LTE technology and its infrastructure. It provides on a vision for an accelerated V2X deployment based on a heterogeneous system. Last, we recommend the ITS stakeholders to carry out extensive research and validation works on DSRC capacity for ensuring a large scale deployment.

Enabling bidirectional traffic mobility for ITS simulation in smart city environments

WAVE(Wireless Access in Vehicular Environments) designed for vehicle communication has the features of a short initial link, low latency and high mobility. The success of data transmission in WAVE is affected by the priority and size of data and how many nodes are transmitting the data. In this paper, we tested and analyzed how the success rate of data transmission of each node varies according to the number of nodes, priority and size of data in various cases. Based on the simulation results, it is possible to confirm the success rate of data transmission and delay time for each node and the entire channel, and it can be determined how channel resources should be efficiently used considering these results.

The vehicular ad-hoc network (VANET) is a promising technology in near future. VANET allows vehicles to communicate with each other and with roadside units (RSUs). Wireless Access in Vehicular Environment (WAVE), defined by IEEE, provides the Internet connectivity for vehicles as well as vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication. RSUs can form a wireless mesh network (WMN) as a backbone infrastructure to enhance the performance of VANET. However, WAVE supports only one-hop communications for IP packets in VANET, and existing researches do not consider the compatibility between VANET and WMN infrastructure formed by RSUs. We propose the extended WMN (ExWMN) which has the feasibility to extend WMN to VANET domain. In ExWMN, the vehicles can send IP packets to an access router by using the multi-hop capability of WMN. ExWMN uses the addressing scheme of WMN for the extended VANET domain and exploits geographical routing protocols instead of existing routing protocols of WMN due to VANET characteristics such as mobility and dynamically changing network topologies. ExWMN supports the compatibility between the extended VANET and a WMN infrastructure due to RSUs, which provide a bridging function between them. This paper presents the architecture and the detailed procedures of the ExWMN.

To improve the throughput performance of the Wireless Access in Vehicular Environment (WAVE) system, we propose a multi-channel MAC protocol that is able to adaptively adjust the intervals of Control Channel (CCH) and Service Channel (SCH) according to the probability distribution of the reservation time for service packet in CCH Interval. Numerical results show that our protocol can significantly improve the performance of WAVE system.