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vehicular communications
The document discusses vehicular ad-hoc networks (VANETs) and their applications, particularly focusing on vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications. It classifies applications into safety, convenience, and commercial categories, highlighting their impact on reducing traffic accidents and enhancing vehicular communication efficiency. Additionally, it addresses the challenges and future directions for improving traffic management using these communication technologies.
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- 1. AutoNet 2006 Vehicular Communications (UbiquitousNetworks for Sustainable Mobility)
- 2. AutoNet 2006 Introduction V2V/V2I Communication-basedAutomotive Applications V2V/V2I Application Characterization and Classification 2
- 3. AutoNet 2006 What isa VANET ? Vehicular Ad-hoc Networks Individual nodes different from traditional wireless nodes No power constraint Nodes mostly mobile Extends existing infrastructure Vehicle-Vehicle Communication Vehicle- Infrastructure Communication
- 4. AutoNet 2006 4 Fo r w a r d r a d a r C o m p u t i n g p l a t f o r m E v e n t d a t a r e c o r d e r ( E D R ) P o s i t i o n i n g s y s t e m R e a r r a d a r C o m m u n i c a t i o n f a c i l i t y D i s p l a y (GPS) - Human-Machine Interface - Navigation system
- 5. AutoNet 2006 5 •Processing power: comparable with a Personal Computer + a few dozens of specialized processors • Communication: typically over a dedicated channel: Dedicated Short Range Communications (DSRC) •In the US, 75 MHz at 5.9 GHz; •In Europe, 20 MHz requested but not yet allocated) • Envisioned protocol: IEEE 802.11p • Penetration will be progressive (over 2 decades or so)
- 6. AutoNet 2006 V2V/V2I Communication-based AutomotiveApplications From an application benefit viewpoint, V2V/V2I applications can be classified as Safety Applications Convenience Applications Commercial Applications 6 Safety
- 7. AutoNet 2006 among thoselisted, safety-oriented applications are of special interest because they are expected to significantly reduce the fatalities and economic losses caused by traffic accidents 7 ConvenienceCommercial
- 8. AutoNet 2006 Safety applications SVA(Stopped or Slow Vehicle Advisor) 8
- 9. AutoNet 2006 PCN:V2V Post Crash Notification EEBL: Emergency Electronic Brake Light RHCN: Road Hazard Condition Notification RFN: Road Feature Notification CCW: Cooperative Collision Warning CVW: Cooperative Violation Warning
- 10. AutoNet 2006 Convenance Applications CRN(Congested Road Notification) 10
- 11. AutoNet 2006 TP:Traffic Probe TOLL: Free Flow Tolling PAN: Parking Availability Notification PSL: Parking Spot Locator
- 12. AutoNet 2006 Commercial Applications RVP/D: Remote Vehicle Personalization/Diagnostics SA: Service Announcements CMDD: Content, Map or Database Download RTVR: Real-Time Video Relay
- 13. AutoNet 2006 V2V/V2I ApplicationCharacterization and Classification Application Characteristics describe properties directly related to the applications themselves 13
- 14. AutoNet 2006 Classification Criteria:Network Attributes Networking Attributes characterize the fundamental aspects of network design for communication- based automotive applications 14
- 15. AutoNet 2006 Application CharacteristicCharacterization 15 Applications exhibit commonalities!
- 16. AutoNet 2006 Network AttributeCharacterization 16
- 17. AutoNet 2006 Application Classification(1) 17 Networking Attributes Perspective 1. Safety - SVA, EEBL, PCN, RHCN, RFN, CCW, CVW 2. Convenience - CRN, TP, TOLL, PAN, PSL 3. Commercial - RVP/D, SA, GMDD, RTVR Application Benefit Perspective Short Message Communications Content Download/Steaming Broadcast Unicast File Download Video Streaming Event- driven Periodic On-demand Financial Non Financial Unicast
- 18. AutoNet 2006 Application Classification(2)Group applications into 7 generic classes: Accommodate the applications of interest Class Name Representative Applications 1 Event-Driven Short-Message Broadcast SVA, EEBL, PCN, RHCN, and RCN 2 Scheduled (Periodic) Short-Message Broadcast CCW ( Cooperative Collision Warning), CVW (Cooperative Violation Warning) 3 On-Demand Short-Message Broadcast SA (Service Announcements) 4 Financial Transaction Short-Message Unicast RVP/D (Remote Vehicle Personalization/Diag) TOLL (Free Flow Tolling) 5 Non-Financial Transaction Short- Message Unicast TP, PAN, PSL 6 File Download CMDD (Contents, Map or Database Download) 7 Video Streaming RTVR (Real-Time Video Relay) 18 - Only (7 generic classes) application models - Individual applications are simple extensions from the generic models SVA: Stopped or Slow Vehicle Advisor EEBL: Emergency Electronic Brake Light PCN: V2V Post Crash Notification RHCN: Road Hazard Condition Notification RFN: Road Feature Notification TP: Traffic Probe PAN: Parking Availability Notification PSL: Parking Spot Locator
- 19. AutoNet 2006 Performance Metricsfor Communication- based Automotive Applications We mainly concentrate on safety applications, since they are the initial focus of automotive industry Necessity to introduce novel application-level metrics to accurately capture performance trends of safety applications 19 Level Metric Description Classes Network Packet Delivery Ratio packets received / packets transmitted 1, 2, 3, 4, 5, 6 Network Per-Packet Latency packet reception time – packet transmission time 1, 2, 3, 4, 5 Application T-window Reliability prob. of receiving at least one transmitted packet within a given time interval 1, 2, 3 Application Time-to-Successful Reception application-level packet reception latency 1, 2, 3 Application QoS Metrics end-to-end packet delay, jitter, and throughput 7
- 20. AutoNet 2006 ADVANTAGES Reducing thelikelihood of collision at intersections. Reducing the likelihood of road departure crashes. Providing more accurate and timely road condition alerts. 20
- 21. AutoNet 2006 DISADVANTAGES The wholesystem cannot be work without network connectivity This process can be done if and only if every vehicle should active their communication system 21
- 22. AutoNet 2006 APPLICATIONS UsingV2V communication, when a vehicle on the road acts abnormally, e.g., deceleration exceeding a certain threshold, dramatic change of moving direction, major mechanical failure, etc., it becomes an abnormal vehicle (AV). An AV actively generates Emergency Warning Messages (EWMs), which include the geographical location, speed, acceleration and moving direction of the AV, to warn other surrounding vehicles. A receiver of the warning messages can then determine the relevancy to the emergency based on the relative motion between the AV and itself. 22
- 23. AutoNet 2006 FUTURE SCOPE The authors are currently investigating efficient communication mechanisms to disseminate CoTEC’s road traffic congestion information to vehicles approaching the congested area. Using this information, vehicles would be able to modify their route, and select alternative ones that avoid the congested area. An interesting research area would then be to investigate how to efficiently couple V2V-based road traffic monitoring mechanisms with cooperative traffic management strategies. Such coupling should be studied in large scale scenarios in order to better understand the impact on road traffic conditions, and the capability of cooperative systems to efficiently distribute road traffic flows. 23
- 24. AutoNet 2006 CONCLUSION Cooperativevehicular communications open new possibilities to develop advanced traffic monitoring solutions in next-generation ITS systems. In this context, this paper has presented CoTEC, a novel distributed technique using V2V communications to detect and characterize traffic congestion. The proposed technique includes mechanisms to compensate the impact of radio propagation on the accurate estimation of traffic density, and to account for the gradual market introduction of cooperative vehicular communications. 24
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Editor's Notes
- #14 Appropriately lower the tone: we attempted to be as general and as thorough as possible, we acknowledge that future analysis of a broader set of applications may uncover other important characteristics. Indeed, it is our hope that the work presented here will inspire others to research and expand the list as future applications are explored and developed. However, as we will show, this list covers a sufficiently broad range of applications to be a useful reference tool for application and network designers.
- #15 Key point: These attributes, summarized in Table 3, are more or less, are determined by the application characteristics discussed in the previous section,
- #16 Key point: 1. Notice that most of the safety applications have a medium-sized effective application range (i.e., a few hundred meters to 1 kilometer), since safety messages, such as vehicular kinematics status or road conditions, are only relevant to other vehicles within a moderate geographical region. Exceptions are the CCW and CVW applications, which have a small application effective range because they require the closer monitoring of vehicles in their direct neighborhood (i.e., within 200 meters). Conversely, convenience applications generally require a medium or large effective range (i.e., up to a few kilometers), because it is vital for drivers to know the congestion situation or traffic condition at this range for effective detour or trip planning. Similarly, commercial applications also tend to have a large effective range in order to access remote commercial service providers4. 2. Most safety applications (e.g., EEBL, RHCN and SVA) and a few convenience applications (e.g., CRN, TP and TOLL) are initiated by the events happening on the road, such as vehicle collisions, detection of road hazards (e.g. ice, oil), sudden braking, or detection of traffic congestion. If no such events happen, these applications will not be invoked. Among safety applications, CCW and CVW are unusual because they rely on the periodical message updates to monitor the neighboring vehicles’ driving status, regardless of safety events. On the other hand, most convenience applications and commercial applications are triggered on-demand by vehicle occupants, rather than by any safety event on the road or the vehicle itself. 3. The potential recipients of application messages, in most safety applications (e.g., SVA and EEBL), are vehicles within a specific zone (i.e., behind the vehicle which detects the event and originates the safety message). Thus, safety applications can be summarized as one-to-a-zone recipient patterns5. At the same time, convenience and commercial applications vary from application to application: some convenience applications (e.g. TOLL) and commercial applications (e.g., RVP/D, CMDD, and RTVR) have point-to-point (one-to-one)modes, while other convenience applications (e.g., CRN) and commercial applications (e.g., SA) are fundamentally one-to-a-zone in nature. 4. “Event” is an important concept in safety applications, and a few convenience applications, because it is an event that initiates the application operations. In our study, we also characterize safety events via several properties of events, including event duration, event correlation, and event detectors. Consistent with our conjecture, we find that safety events drastically vary from application to application. For example, sudden braking (EEBL) is a one-shot event, while road hazard/feature events (RHCN or RFN) are persistent events. Also, different instances of RHCN or RFN events caused by the same road hazard/feature are more likely to be correlated with each other, in contrast to the totally independent PCN events. Even though the study of event characteristics is not directly used in the network design conducted in Section 4.2, we believe that such an analysis can help future network designers better capture the data traffic patterns induced by event-driven safety applications.
- #17 Key point 1. The message packet format is determined by the type of application (from the perspective of user benefit). Normally, safety and convenience applications use light-weight shortmessages in theWSMP format, to improve network resource efficiency. Commercial applications, on the other-hand, generally prefer the traditional heavyweighted IP format to be compatible with existing Internet commercial services. 2. The network-layer routing protocol is one essential component in a network stack, differentiating the reachability and recipient patterns of various applications. Most safety applications utilize multi-hop geocast routing protocols6, because of the one-to-many communication nature in safety applications. CCW and CVW applications, instead, use the single-hop broadcast scheme to announce the periodic update in their direct neighborhood. Convenience and commercial applications either use geocast/broadcast protocols to announce messages in a region (for advertisement service like SA, or traffic congestion notification like CRN), or exploit unicast protocols to forward packets to a given destination (for financial transactions like TOLL, or data download from infrastructure like CMDD). 3. The method by which the network routing protocol is triggered is another interesting design choice to be examined in our study. Event-driven safety applications (e.g., SVA, EEBL and CRN) require the event-triggered mechanism in network protocols, periodic-based safety applications (e.g., CCW and CVW) mandate the periodic beacon (or hello message) mechanism, and user-initiated convenience and commercial applications (e.g., SA, RVP/D and PSL) are triggered in an on-demand fashion. 4. The involvement of infrastructure in network design and application development is another key issue for consideration7. Normally, as a rule of thumb, safety applications often do not assume the participation of road-side infrastructure. On the contrary, infrastructure can facilitate the design of convenience applications as well as enable commercial applications by providing the gateway to the existing Internet infrastructure8. As a side note, the involvement of infrastructure also complicates the design of security solution. We believe that security solutions for V2V applications are different from that for V2I applications, depending on whether PKI structure can be utilized. Also, the gateway to the Internet requires the compatibility of V2V/V2I security solutions with the existing Internet security solutions.
- #18 Motivation of classification and generalization: the obvious similarity between applications! (1) RHCN and RFN are nearly the same, except that the type of safety warning messages are different: RHCH is about road hazards, while RFN is about road features. (2) PCN and RHCN are also similar except for the number of event originators: PCN has a sole message host, while RHCN has multiple message hosts. Even though this difference gives rise to different levels of data traffic burstiness from event generation, the network protocol stacks for these two applications are still similar to each other. (3) Also, CCWand CVWapplications can be categorized into the same type, although the former is a V2V application whereas the latter is a V2I application.