Demo: Human-Interactive Hardware-In-the-Loop Simulator for Cooperative Intelligent Transportation Systems and services

Enabling bidirectional traffic mobility for ITS simulation in smart city environments

Today, more and more vehicles on the road are being connected via roadside communication networks for a wide range of services, ranging from road safety and navigation applications to in-vehicle entertainment. Cooperative Intelligent Transport Systems (C-ITS) services are aiming to improve road safety, traffic management and environmental performance of road transportation by sharing data between vehicles and road operator’s infrastructure via roadside communication networks. This paper investigates the capacity requirements of roadside ITS-G5 and cellular communication networks for supporting the emerging C-ITS applications, based on the C-ITS pilot implemented by Transport Infrastructure Ireland (TII). The results indicate that although the current communication networks are able to support the capacity demand of C-ITS applications at a low penetration rate of C-ITS equipped vehicles during the early uptake of C-ITS, new measures are required to improve the capacity of roadside communication networks when the number of C-ITS applications or the penetration rate of C-ITS equipped vehicles on the road goes high.

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.

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.

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.

Recently, the IEEE 1609.4 Standard for Wireless Access in Vehicular Environments (WAVE) has been proposed to enhance the performance of vehicular networks with multi-channel operations that allow for the coexistence of safety-related and non-safety related vehicular applications. However, while the benefits of the multi-channel approach are clear, the impact of the IEEE 1609.4 channel scheduler on the performance of delay-constrained vehicular applications remains to be well explored by researchers. At present, the evaluation of 1609.4-based Vehicular Ad Hoc Networks (VANETs) constitutes an open issue due to the lack of simulation tools that can provide a complete modeling of the IEEE WAVE 802.11p/1609.4 stack. In this paper, we provide three key contributions pertaining to multi-channel VANETs. First, we describe our implementation of the IEEE 1609.4 protocol in the ns2 simulator, and we detail its current integration with the existing ns2 implementation of the 802.11p MAC protocol. Second, using our simulation model we propose an evaluation study of 1609.4-based VANETs, and we show that the tight channel synchronization issues foreseen by the protocol might have a dramatic impact on the performance of safety-related applications with strict delivery ratio and delay requirements. Third, we propose two new enhancements for the WAVE protocol stack to favor the dissemination of safety messages in multi-channel VANETs. The suggested algorithms are shown to greatly improve packet delivery ratio and delay of safety applications in single and multi-hop topologies, while preserving the synchronization scheme of the IEEE 1609.4 protocol.

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.

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.

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.

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.

The current medium access control (MAC) protocol of the wireless access in vehicular environments (WAVE) system is based on IEEE 802.11 distributed coordination function (DCF) and enhanced distributed channel access (EDCA), which have drawbacks in supporting throughput-sensitive non-safety applications in vehicular ad-hoc network (VANET). In order to address the problem, we propose a novel MAC protocol, namely vehicular MESH network (VMESH), which is specifically designed for the control channel (CCH) and multiple service channels (SCHs) structure of WAVE. A synchronized and distributed beaconing scheme is employed in the VMESH protocol for the purposes of neighborhood awareness and dynamic resource reservation on SCHs. The advantages of the VMESH protocol in supporting the throughput-sensitive non-safety applications in VANET are shown through the theoretical analysis comparing to the current WAVE MAC.

Wireless Access in Vehicular Environments (WAVE) protocol stack is the most important protocol used to allocate spectrum for vehicular communication. The capabilities of WAVE to provide reliable exchange of safety information are questionable. In a previous work, we suggested a system that employs cognitive networks principles to increase the spectrum allocated to the control channel (CCH) by the IEEE 802.11p amendment, where all safety information is transmitted. However, the decision making process implemented in that work does not differentiate between contention levels and does not relate precisely the measured contention to the amount of needed spectrum, which leads to an inefficient utilization of the white spectrum. In order to assign the minimum necessary additional bandwidth to relieve the contention, we suggest in this paper a new system that quantifies contention into multiple levels of severity based on Fuzzy Logic and maps additional spectrum correspondingly. Simulations show the effectiveness of the system in allocating the minimum needed bandwidth to relieve contention, without affecting other QoS parameters such as delay and number of untransmitted packets.

Recent V2X communication technology provides safety and service information in real time for autonomous driving. It has been researched more improved performance rather than legacy wireless access in vehicular environments (WAVE) through high data rate and low packet latency. However, quality of service(QoS) cannot currently be guaranteed, because original physical and medium access control(MAC) layer have been optimized for low mobility. This paper focuses on the implementation of enhanced MAC layer of WAVE and proposes a new channel access method for QoS.

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.

Dedicated short range communication (DSRC) is the key component in intelligent transportation systems (ITS). The goal of this technology is to help driver and passengers getting multimedia services via wireless communication equipment during the movement of vehicle, so as to improve the traffic safety and enhance the transportation efficiency. The paper is focus on the DSRC baseband technical analysis and the application development. Based on the WLAN 802.11a architecture, we develop a new adaptive channel estimation algorithm that uses two kinds of feedback tracking and pilot aid to enhance wireless access ability in vehicular environments.