Author: Wang Yiming
Source: IoT Jianghu (iot521)
Since the day automobiles were born, safety and convenience have always been the most important topics for urban traffic. Faced with the increasing number of vehicles on city roads, along with the rising risks of accidents and traffic pressure, urban managers and researchers in the transportation field have utilized traffic signal facilities to achieve traffic control and continually innovate.
In the 1860s, the first traffic signal light in the world was installed at the intersection in front of the British Parliament in London (a wall-mounted gas traffic signal). It was operated by a police officer pulling a belt to switch the light colors: red means stop, green means go. Although it alleviated traffic pressure at the intersection, this first traffic signal light exploded and went out of service after just 23 days.
In 1914, Cleveland, Ohio, USA, began deploying electric traffic signals for ground traffic control and coordination, which is considered the earliest traffic signal control system.
In 1918, a three-color (red, yellow, green) traffic signal light appeared on a tower on Fifth Avenue in New York City, and this classic “color scheme” has continued to this day.
In 1926, Wolverhampton in the UK was the first to use an automated controller to control traffic lights, switching the light colors according to a fixed cycle.
In the 1960s, Denver, USA, achieved centralized real-time control of traffic signals through simulation computers, allowing coordinated control of traffic signals at various intersections in the road network. Subsequently, Toronto, Canada, built the first citywide traffic signal centralized control and coordination system.
To this day, the appearance of traffic lights has hardly changed, but the theoretical methods and operational systems of traffic control have been continuously advancing.
From manual operation or fixed-cycle single-point control; to coordinated control of adjacent intersections to ensure continuous green lights along main roads; to continuously optimizing the traffic resources of the entire area (mainly the timing of traffic lights), today’s traffic control technology, while evolving with strong automation and intelligence characteristics, has also reached a performance bottleneck.
Using a single “red-green signal light” model for traffic control can no longer effectively manage traffic resources (insufficient real-time): traffic lights only work at intersections, and their effectiveness cannot cover the entire road; drivers may not be able to see traffic signals clearly due to weather conditions and traffic congestion; drivers are easily caught in the “yellow light dilemma,” where it is difficult to decide whether to “go” or “stop” when the yellow light is flashing; although inducement systems (providing traffic condition information) have been introduced into the traffic network, and drivers can use real-time feedback navigation systems, the overall effect on road utilization is not significant…
Urban roads need to accommodate more vehicles and meet more travel demands, which requires breaking through the original technical fields and developing towards deeper informatization and intelligence.
The idea of “intelligent transportation” emerged as early as the early 20th century, closely related to urbanization: urban managers hoped it could solve the increasingly congested state of urban roads and the economic losses caused by it. In the 1990s, the concept of Intelligent Transportation Systems (ITS) gradually took shape.
Currently, ITS has been widely applied in many developed countries, and its research and promotion work shows a “tripartite balance (leading)” situation: the USA, Europe, and Japan (ITS America, ERTICO, VERTIS).
The initial intention of building ITS was to integrate more information technology into traffic control systems to solve issues of resource utilization and safety in traffic. However, today it also carries other functions: increasing travel comfort, assisting or automating driving, improving transportation efficiency (including enhancing energy utilization and providing the shortest path), value-added services, and so on.
Intelligent transportation is an interdisciplinary field that involves various traffic elements: roads, vehicles, drivers and passengers, toll stations and bus stations, information technology, pedestrians, regulations, etc.; encompassing various traffic management systems and services: traffic information services, vehicle management, electronic toll collection, emergency rescue, inducement information services, etc. (Note: “Interpreting the Internet of Things” – Machinery Industry Press)
The applications of intelligent transportation mainly include vehicle safety, electronic toll collection, highway and vehicle management, navigation and positioning, commercial fleet management, and so on.
The construction of intelligent transportation is a deep integration of information technology and transportation. Communication networks, computer technology, sensing technology, and software industry are the keys to achieving ITS.
The World Road Association defines ITS as a collective term for various information systems that integrate applications of “automatic data sensing and collection,” “network communication,” “information processing,” and “intelligent control” in the transportation field, making the transportation industry safer, more efficient, environmentally friendly, and comfortable.
From the definition of ITS, we can see that the essence of the development of intelligent transportation systems is the combined evolution of “information technology” and “transportation technology”.
3.1 Started in the 70s:
In 1970, the United States proposed the Electronic Route-Guidance System (ERGS), which provides vehicle navigation services through roadside devices.
In 1973, Japan launched the Comprehensive Automobile Traffic Control System (CACS) project, which was Japan’s first ITS project. It guides vehicles through roadside devices to reduce congestion, avoid safety accidents, and provide emergency services.
3.2 The Triumvirate in the 80s:
In 1986, the European Union launched the Program for European Traffic with Highest Efficiency and Unprecedented Safety (PROMETHEUS).
The aim was to study advanced traffic information technologies such as vehicle-to-vehicle communication (PRO-NET), vehicle-to-road communication (PRO-ROAD), and assisted driving (PRO-CAR). Additionally, the EU also began researching the “European Road Infrastructure Program for Vehicle Safety (DRIVE)” at the same time.
In 2000, the EU released the KAREN project, which included the ITS framework. In 2009, it began commissioning multiple agencies to establish unified ITS standards. In 2011, the EU launched the Drive C2X project, aiming to create a safe, efficient, and environmentally friendly driving environment, which was announced as successfully tested in 2014.
In 1992, the United States formulated a research plan for the Intelligent Vehicle Highway System (IVHS), and in 1995, the Department of Transportation officially announced the “National ITS Program Plan.” In 2009, the U.S. Department of Transportation released the “Intelligent Transportation Systems Strategic Research Plan: 2010-2014,” clarifying the concept of the Internet of Vehicles.
In 2014, the U.S. planned to mandate the promotion of vehicle-to-vehicle communication (National Highway Traffic Safety Administration: “Notice of Proposed Rulemaking,” “V2V Technology Application Ready”), and in 2015, the U.S. Department of Transportation launched the Connected Vehicles project.
Based on previous research results (Vehicle-to-Vehicle Communication System – RACS, Traffic Information Communication System – TICS), in 1995, the Japan Road Traffic Information Center established the Vehicle Information and Communication System Center (VICS). Drivers can enjoy free traffic information services through onboard navigators equipped with the VICS system.
Starting in 2000, the Electronic Toll Collection (ETC) system was vigorously developed in Japan.
In 2002, the VICS center began providing traffic information to mobile phones, PDAs, personal computers, and other terminals.
In 2003, the Advanced Cruise-Assist Highway Systems (AHS) project was officially implemented, which provides safe driving services through vehicle-to-road communication cooperation (using DSRC, Dedicated Short Range Communication).
The Internet of Vehicles/Onboard Network is an important component of ITS.
In intelligent transportation, compared to research in other fields (such as urban public transport management, traffic inducement and services, etc.), research on the Internet of Vehicles/Onboard Network started the latest, and some areas are still at a preliminary stage.
Globally, there are two main communication technology standards for the Internet of Vehicles: DSRC (IEEE) and LTE-V (3GPP), supporting vehicles to connect to all relevant entities, including road facilities, other vehicles, people, etc.
4.1 DSRC
In the development of intelligent transportation, Dedicated Short Range Communication (DSRC) technology is one of the foundations of ITS. It has continually evolved alongside intelligent transportation, with significant breakthroughs in related technology starting in the 1990s.
In 1992, ASTM (American Society for Testing Materials) first proposed the concept of DSRC technology, primarily for the development of ETC services, and standardized work was carried out in the 915 MHz frequency band.
In October 1999, the Federal Communications Commission in the U.S. allocated dedicated channels for V2V and V2I types of short-distance connections (DSRC, Dedicated Short-Range Communication) in the 5.9 GHz band.
In 2001, the relevant standards committee of ASTM selected IEEE802.11a as the underlying wireless communication protocol for DSRC.
In 2004, IEEE revised the IEEE802.11p protocol specification and established a working group to start the standardization work for Wireless Access in the Vehicle Environment (WAVE), initiating the VII/IntelliDrive project for further technical research on vehicle-road cooperation.
In the same year, the first VANET academic conference was held in Philadelphia, USA, where the term “VANET” was officially used for the first time.
In 2010, the WAVE working group officially released the IEEE 802.11p vehicle networking communication standard. This standard, as the vehicle electronic wireless communication specification, is applied in intelligent transportation (ITS) systems and has become the underlying protocol (MAC layer/PHY layer, i.e., data link layer and physical layer in the OSI model) under the DSRC standard.
Europe began drafting the DSRC standard as early as 1994 by CEN (European Committee for Standardization). In 1995, the European DSRC standard draft was completed and approved in 1997 (ENV12253 “5.8GHz-DSRC-Physical Layer” and ENV12795 “DSRC-Data Link Layer”).
In 2001, six European automotive manufacturers (BMW, Volkswagen, Daimler-Chrysler, etc.) joined suppliers and research institutions to establish the Car 2 Car Communication Consortium (C2C-CC), aiming to develop vehicle-to-vehicle communication functions using wireless LAN technology and establish communication standards between vehicles and infrastructure in Europe.
To solve vehicle-to-vehicle communication issues, in 2004, BMW and Volkswagen joined the FleetNet project’s follow-up project (2000): NOW (Network on Wheels), focusing on vehicle-to-vehicle communication and ensuring data security.
In 2008, the European Telecommunications Standards Institute (ETSI) allocated dedicated channels for vehicle networks in the 5.9 GHz band.
In the EU’s Sixth Framework Programme, many intelligent transportation projects (also known as the “eSafety project”) are promoting the development of Internet of Vehicles/Onboard Network-related technologies: COOPERS (Intelligent Transportation Safety Assistance System – Austria Tech), CVIS (Cooperative Vehicle-Infrastructure System – European Intelligent Transportation Association), SAFESPOT (SAFESPOT project – Fiat Research Center), etc.
In 1994, Japan conducted field tests of the ETC toll collection system in collaboration with multiple enterprises and selected frequencies for DSRC. In 1997, the TC204 committee in Japan formulated Japan’s DSRC standard. The ETC system officially began service in 2001.
In 1999, Japan (23 enterprises) launched the Smart Way project, mainly to provide various information exchange infrastructures in traffic scenarios, with the communication methods of various facilities mainly adopting DSRC. (Note: Japan’s VICS, ETC, and AHS currently belong to the Smart Way project.) In 2007, Japan initially completed the test plan for some sections of the Smart Way project.
Japan’s DSRC is set by ISO/TC204 and supports the final IEEE 802.11p version (USA).
4.2 LTE-V
In 2006, several companies in the communication and automotive fields (Ericsson, Vodafone, MAN Trucks, Volkswagen) joined forces to promote the Cooperative Cars project, aiming to study the use of cellular communication technology (using 3G networks) to achieve mutual transmission of driving warning information (between vehicles and between vehicles and road management systems).
Subsequently, BMW and Ford joined the CoCarX project, achieving good performance test results in vehicle-to-vehicle cooperative communication under LTE network coverage.
In 2012, the EU funded the LTEBE-IT project to conduct research on the application of LTE evolution protocols in ITS.
In 2015, the 3GPP international organization established the topics “Research on LTE Support for V2X Services” and “Feasibility Study of V2X Based on LTE Network Technology,” officially launching the standardization research of LTE V2X technology. In the industry, “LTE-V2X” (LTE: Long Term Evolution, i.e., 4G communication technology; V2X: Vehicle to Everything) is abbreviated as “LTE-V,” which is a vehicle networking technology based on wireless cellular communication, also known as “C-V2X (Cellular-Vehicle to Everything).” Many domestic communication companies (Huawei, Datang, ZTE) participated in the R&D of LTE-V.
In September 2016, 3GPP completed the standardization of various types of communication in the Internet of Vehicles (vehicle-to-vehicle cellular communication, vehicle-to-road facility communication, vehicle-to-person communication, etc.) in the “LTE-based V2X Services” project.
In the 5G communication standard of 3GPP, LTE-V will gradually evolve into NR-V2X.
4.3 Internet of Vehicles and Intelligent Transportation
From the development history of DSRC and LTE-V, it can be seen that DSRC started earlier and has already emerged in many ITS research projects, achieving some relatively mature applications of the Internet of Vehicles. (For example, various sub-projects in Japan’s Smart Way, Europe’s COOPERS, CVIS, SAFESPOT, PreVENT projects, and the ETC applications in the USA, VII/IntelliDrive projects).
Before the LTE-V standard, vehicles connected to networks using 3G/4G cellular wireless technology, referred to as Telematics (a synthesis of Telecommunications and Informatics, meaning a network combining long-distance communication technology and information technology).
Telematics is a common form of the Internet of Vehicles, but since it only achieves connectivity between vehicles and the cloud, it is also understood as “narrow-sense Internet of Vehicles.” The emergence of LTE-V attempts to break the original situation where cellular access networks could only supplement DSRC technology, integrating short-distance, direct, non-IP communication technology (PC5 interface) with cellular communication technology to form a complete communication technology system in the field of the Internet of Vehicles.
From the research models of various countries on the Internet of Vehicles, due to the complex application scenarios of ITS, diverse demands, and numerous types of terminals, research on the Internet of Vehicles needs to advance in sync with the development of ITS applications to meet the technical details required during driving.
To achieve higher levels of safety, efficiency, and environmental protection in production (driving), vehicles (as well as transportation supporting equipment and systems) need to possess more and stronger perception, communication, and computing capabilities (intelligence), thereby enhancing the overall informatization capability of the transportation system to achieve an upgrade of the entire transportation field.
In other words, Internet of Vehicles technology develops synchronously with sensing, computing (such as autonomous driving), software development, and other information technologies. The future “intelligent transportation” will deeply integrate transportation (road) networks and information networks.
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