Inter-Vehicle Communications (IVC): Current Standards and Supporting Organizations Scott E. Carpenter North Carolina State University, Department of Computer Science
June, 2013
[email protected], 919-413-5083
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Copyright © 2013 Scott E. Carpenter
Agenda • Objectives • IVC Concepts • Standards – IEEE 802.11p – IEEE 1609 – SAE J2735
• Organizations – Vehicle Infrastructure Initiative (VII) (a.k.a. IntelliDrive) – Vehicle Safety Communications (VSC) – Intelligent Transportation Systems (ITS)
• Challenges • Conclusions 2
Copyright © 2013 Scott E. Carpenter
Objectives • Create a Microsoft PowerPoint (PPT) presentation exploring the following with respect to IVC : – An overview of the IEEE 1609 standards, specifically: • • • •
IEEE 1609.1 IEEE 1609.2 IEEE 1609.3 IEEE 1609.4
• Focus on the Network Layer. • An overview of Vehicle Infrastructure Initiative (VII) and other IVCrelated consortia. • Recent research / applicability of geocasting. • Are communications paradigms from IPv6 applicable? • Pertinence of roadside internet technologies. • Consider “problems” in terms of “I think I can do that!” 3
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Inter-Vehicle Communications (IVC) •
Promises – – –
•
Increased traffic efficiency Accident reduction / safety improvements Info / entertainment applications
Classifications – by service • •
Vehicle Control Information Services
– by technical requirements • • • • •
•
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Digital bandwidth Latency Reliability Security and authentication Network configuration
Requires wireless ad-hoc network Copyright © 2013 Scott E. Carpenter
Ad-Hoc Network Classifications • Wireless Mesh Network (WMN) • Wireless Sensor Network (WSN) • Mobile Ad-Hoc Network (MANET) – Vehicular Ad-Hoc Network (VANET) – Internet Based Mobile Ad-hoc Network (iMANET) – Intelligent vehicular ad-hoc network (InVANET)
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VANET Technologies • DSRC typical • Other technologies utilized, too.
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VANET Exploration – A Brief History • Recent: – WAVE • (IEEE 1609)
– VSC • (completed)
– VII • (completed)
– ITS • (RITA, USDOT)
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OSI vs. WAVE
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WAVE Protocol Stack • 1609.1 – Resource manager (a specific transponderlike application)
• 1609.2 – Security issues
• 1609.3 – Networking services
• 1609.4 – Multi-channel operation
• Note dual networking stack: – IPv6 – WSMP 9
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IEEE 802.11p • Extends 802.11 in the following 4 ways: – Transmission outside the context of BSS – Because the V2I link might exist for only a short amount of time, the IEEE 802.11p amendment defines a way to exchange data through that link without the need to establish a BSS. Authentication and data confidentiality mechanisms must be provided by higher network layers. – Timing advertisement - allows stations to synchronize themselves with a common time reference. – Enhanced receiver performances - Optional enhanced channel rejection requirements, applicable only to OFDM transmissions in the 5GHz band (for both adjacent and nonadjacent channels), are specified in order to improve the immunity of the communication system to out-of-channel interferences. – Use of the 5.9GHz band - Allows the use (in the U.S. and Europe) of the 5.9GHz band (5.850-5.925 GHz) with 5MHz, 10MHz and 20MHz channel spacings.
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IEEE 1609 IEEE 1609 WG - Dedicated Short Range Communications Working Group Standards (As of 6/4/2013) Active 1609.2-2013 IEEE Standard for Wireless Access in Vehicular Environments — Security Services for Applications and Management Messages 1609.3-2010 IEEE Standard for Wireless Access in Vehicular Environments (WAVE) Networking Services 1609.3-2010/Cor 1-2012 IEEE Standard for Wireless Access in Vehicular Environments (WAVE)--Networking Services Corrigendum 1: Miscellaneous Corrections 1609.4-2010 IEEE Standard for Wireless Access in Vehicular Environments (WAVE)-Multi-channel Operation 1609.11-2010 IEEE Standard for Wireless Access in Vehicular Environments (WAVE)-Over-the-Air Electronic Payment Data Exchange Protocol for Intelligent Transportation Systems (ITS) 1609.12-2012 IEEE Standard for Wireless Access in Vehicular Environments (WAVE) Identifier Allocations
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Withdrawn / Superseded Standards
Status
1609.1-2006 Trial-Use Standard for Wireless Access in Vehicular Environments (WAVE) - Resource Manager
Withdrawn
1609.2-2006 Trial-Use Standard for Wireless Access in Vehicular Environments Security Services for Applications and Management Messages
Withdrawn
1609.3-2007 IEEE Trial-Use Standard for Wireless Access in Vehicular Environments (WAVE) - Networking Services
Superseded
1609.4-2006 Trial-Use Standard for Wireless Access in Vehicular Environments (WAVE) - Multi-Channel Operation
Withdrawn
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Packet Reception • The probability of packet reception can be influenced by: – – – – – –
Vehicular traffic density Radio channel conditions Data rate Transmit power Contention window sizes Packet prioritization
• Major challenge in adjusting the parameters to match the goals of applications.
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Packet Prioritization • Enhanced distributed channel access (EDCA) principles can be used. • Four access categories with independent channel access queues are provided. • Prioritized channel access (based on IEEE 802.11e) can be shown to lead to improved channel access times and higher probability of reception for those packets that receive a higher priority.
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Data Rate, Saturation • Google driverless car collects 750 MB of sensor data per second – Unclear what the min. data needs are for IVC
• Yet, claims are made that IVC networks should support a variety of vehicular applications – even in high vehicle density scenarios without adverse impact to capacity and delay performance.
• Out-of-the-box IEEE 802.11p alone is not sufficient to provide an appropriate level of quality of service to support traffic safety-related applications!
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Power Effects
• Increasing Tx power combats fading, but increases saturation. • Controlling beacon load with distributed power control (TxPC) increased probability of receipt.
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Multichannel • Multichannel operations is one of the biggest challenges for IVC. • 7 Channels, time-multiplexed •
(1) Command channel (CCH) •
•
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Serviced every other timeslot
(6) Service channels (SCH)
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Channel Prioritization • 4 access categories (per channel) • Queues have different timer settings.
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Single-Hop, Multi-Hop • One-hop: • Periodic • VSC recommends rate of 10 msgs / sec, with max. latency of 100 ms and min. range of 150 m.
• Event-driven
• Multi-hop • Strongly dependent on vehicle location • Classical position-based forwarding • Contention-based forwarding (CBF)
• Single-radio devices may periodically and synchronously switch between CCH and SCHs • Dual-radio devices could have one radio tuned to the CCH and the second radio tunable to one of the available service channels 18
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Communications Range - Geocasting • Geocasting protocols: • Reactive • Reactive geocast protocols decide the next-hop forwarder at each hop through a distributed contention phase among the neighbors of the vehicle that generated the message.
• Proactive • Proactive geocast protocols determine the message forwarders before the effective message dissemination, through the creation of a virtual backbone of vehicles inside the VANET.
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Vehicular Roadside Internet Access • Challenges – – – – –
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Load Balancing: Location Discovery: Security: Uninterrupted Roaming Facility:. Maximized Coverage Area:
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Vehicular Roadside Internet Access (2) • Integration Strategies – Instantaneous link quality (ILQ) based relay protocol – Utilize the vehicles location to estimate the ALQ for relay selection – A new opportunistic relay protocol for vehicular roadside AP (from ORPVRAFC). – Sparse deployment of roadside Wi-Fi. • New metric for roadside Wi-Fi called contact opportunity, which measures the fraction of distance or time that a user in vehicle is in contact with some AP when moving through certain path. Use empirical results from a measurement study
– Mob Torrent, an on demand user driven frame work for vehicles which have high speed access to roadside Wi-Fi APs.
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Vehicular Roadside Internet Access (3)
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Security and Privacy • Security – Key issue is data authenticity (broadcast authentication) • Public key infrastructure (PKI), using certificate authorities (CAs).
– Message authentication using Elliptic Curve Digital Signature Algorithm (ECDSA) – Large computational burden of digital signature verification leading to exploration for alternatives. • E.g. lightweight broadcast authentication, timed efficient stream losstolerant authentication (TESLA)
• Privacy – Tension between the receiver’s goal of strong message authentication and the sender’s goal of strong privacy. – Consideration for multiple pseudo-identifiers per vehicle
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IEEE 1609.1 (Resource Manager) • WAVE RM, acting like an application layer, allows applications at remote sites to communication with OBU. – Note: Processing, memory, and configuration management requirements are removed from the OBU and thus application independent.
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IEEE 1609.1 (Resource Manager) (2) • Typical data flow:
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IEEE 1609.2 (Security Standards) • Key features of WAVE security services: – Provide authentication, authorization, integrity, confidentiality services. – Designed to increase bandwidth and processing time by the minimum amount consistent with the security requirements. – Are not at a particular location in the stack, but may be called by any functional entity on a WAVE device.
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IEEE 1609.2 Security Mgmt. Services • Security services: – Certificate Management Entity (CME) (CME-Sec-SAP) (CME-SAP). – Provider Service Security Management Entity (PSSME)
• Security processing services: – – – – – – – – –
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Generate signed data Generate encrypted data Verify signed data Decrypt encrypted data Generate signed WAVE service advertisement (WSA) Verify signed WSA on reception Generate certificate request Verify response to certificate request Verify certificate revocation list
Copyright © 2013 Scott E. Carpenter
IEEE 1609.3 (Networking Services) • Specifies network and transport layer protocols and services that support high-rate, low-latency, multi-channel wireless connectivity. • Key services: – – – –
LLC IPv6 / UDP / TCP WSMP WME • Service requests and channel access assignment • Management data delivery • WAVE Service Advertisement monitoring • IPv6 configuration • MIB maintenance
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IEEE 1609.3 Channel Access Options • Channel access options: – – – –
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Continuous Alternating Immediate Extended
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IEEE 1609.3 Channel Access Assignment • Example data flow for channel access assignment
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IEEE 1609.4 (Multi-channel Operations) • Channel coordination (OCBEnabled), per 802.11p • MLME: – Data Plane services • Channel coordination • Channel routing • User priority
– Management services • • • • • •
Multi-channel synchronization Channel access Vendor-specific action frames Other IEEE 802.11 services MIB maintenance Readdressing – Pseudonymity
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IEEE 1609.4 Channel Coordination • Data is prioritized according to access category (directly related to user priority) – Uses IEEE 802.11 EDCA mechanism per channel for prioritization 32
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IEEE 1609.4 – Issues • Channel congestion phenomenon following a channel switch – Synchronous channel switching – IEEE 802.11 congestion control and error recovery
• Avoiding transmission at scheduled guard intervals. Can be avoided by: • a) Before delivering an MSDU to the PHY, the MAC issues a PLME-TXTIME.request and the PHY returns a PLMETXTIME.confirm with the required transmit time. • b) If the required transmit time exceeds the remaining duration of the channel interval, the MSDU should be queued in the MAC sublayer until a return to the proper channel occurs. 33
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Vehicle Infrastructure Integration (VII) • Consortium: • Auto Mfg. • Ford • General Motors • DaimlerChrysler • Toyota • Nissan • Honda • Volkswagen • BMW
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IT suppliers USDOT State DOT Professional associations. Copyright © 2013 Scott E. Carpenter
Communications Challenges • Under VII, most of the road system will not have radio coverage. • Requires vehicles to store data, then forward later • Receive data and store, present later (to user) at opportune time. • Locations for upload / download will be locations where all vehicles are trying to utilize the system.
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VII Trials • Michigan, California. • In mid-2007, a VII environment covering some 20 square miles (52 km2) near Detroit will be used to test 20 prototype VII applications
• Some auto-makers conducting their own trials.
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VII Findings (Overall) • Overall VII POC successful. • However, some shortcomings in WAVE/DSRC radio implementation. • Majority of shortcomings result from the dynamic nature of the mobile radio relative to the stationary radio and to other mobile radios
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VII Findings – DSRC, Communications • DSRC • F‐DSRC‐1 Final range testing results showed solid radio communications from RSE to OBE up to 1100 meters, with multipath effects degrading communications at 660 meters, 850 meters, 900 meters, and 1,000 meters. These results also showed a link imbalance with OBE to RSE communications only available up to 400 meters. • F‐DSRC‐4 Testing showed that the DSRC standards do not adequately address functionality for multiple overlapping RSE coverage areas. •
F‐DSRC‐6 Communication quality was reduced by an “unbalanced link” situation whereby the OBE would commence transmission of data after coming in range of an RSE’s broadcast, but at a distance too far for the RSE to receive the OBE’s data
• Communications Service • F‐COMM‐2 Management of network communications resources for multiple simultaneous applications is more complex than expected 38
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SAE J2735 (DSRC Message Set) • IEEE 1609 do not provide for a standard API • Each application provider needs to develop custom interfaces • SAE J2735 is one such message set, providing
• Primary Message Types: • Basic Safety Message (BSM) – ex: Emergency Electronic Brake Lights. • Roadside Alert (RSA) is the message used in the various traveler information applications, specifically in the Emergency Vehicle Alert message used to inform mobile users of nearby emergency operations. • Probe Vehicle Message (PVM) is used by multiple applications. Vehicles gather data on road and traffic conditions at intervals. 39
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Channel Allocation, Prioritization
• Suggested priority: •
•
•
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Safety of Life - Those Messages and Message Sets requiring immediate or urgent transmission. Ex: Crash-Pending Notification. Public Safety - Roadside Units (RSUs) and On-Board Units (OBUs) operated by state or local governmental entities that are presumptively engaged in public safety priority communications (Includes Mobility and Traffic Management Features). Ex: SPAT (Signal Phase and Timing), Electronic Toll Collection, Heartbeat message. Non-Priority Communications - Fleet Management of Traveler Information Services and Convenience or Private Systems. Ex: Off-Board Navigation Reroute Instructions, Electronic Payments and other E-Commerce applications. Copyright © 2013 Scott E. Carpenter
Vehicle Safety Communications (VSC) • Alternate consortium • Prior to VII
• Identified potential applications: Application Traffic signal violation warning Curve speed warning Emergency electronic brake light Pre-crash sensing Cooperative forward collision warning Left turn assistant Lane-change warning Stop sign movement assistant
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Communications Requirement V2I V2I V2V V2V V2V V2I V2V V2I
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Intelligent Transportation Systems (ITS) • The Intelligent Transportation Systems Joint Program Office (ITS JPO) within the U.S. Department of Transportation’s (U.S. DOT’s) Research and Innovative Technology Administration (RITA) • Responsible for conducting research on behalf of the Department and all major modes to advance transportation safety, mobility, and environmental sustainability through electronic and information technology applications, known as Intelligent Transportation Systems (ITS) • Current “active research” • http://www.its.dot.gov/index.htm. 42
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Key Challenges (1) • Socio-Economic Challenges • •
The beneficial impact of VANETs on traffic safety and efficiency must be shown Equipage penetration rate •
•
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The U. S. contains 4 million miles of roads and streets with an estimated 300,000 signalized traffic lights and, as of 2010, 250,272,812 registered vehicles. Only 1% of roads are highways, though they carry 25% of all vehicular traffic Assuming 40% of all vehicles will be equipped within the next 15 years, at a nominal cost of $150 per unit in today’s dollars, the total costs in today’s dollars to equip vehicles would then be 250,272,812 cars x 40% x $150/car = $15,016,368,720, or slightly more than $1B per year (in today’s dollars) Copyright © 2013 Scott E. Carpenter
Key Challenges (2) • Technical Challenges • •
• • • • • • 44
Accurate traffic modeling (e.g. taking into account human reaction, or feedback loop). The need for adaptive transmit power and rate control mechanisms for periodic one-hop broadcasts in dense traffic Security, privacy, and trust No communications coordinator can be assumed - distributed control with a single, shared control channel. The potential for channel congestion (10 to 20 MHz range) and multi-channel usage leading to synchronization problems. Dynamic network topology and vehicle mobility. Radio propagation issues and adverse radio channel conditions from low antenna heights and attenuation / reflection of moving metal vehicle bodies. Joint optimal transmit and power control is still an open issue Copyright © 2013 Scott E. Carpenter
Simulation – Traffic Modeling •
Traffic Models •
Microscopic • •
Wiedemann car-following model (high fidelity) Nagel-Schreckenburg model (low fidelity)
•
•
•
Traffic Simulation •
Macroscopic Commercial • • •
•
Government •
•
NGSIM (Federal Highway Administration)
Research Community • • •
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VISSIM AIMSUN Paramics
SHIFT STRAW VanetMobSim Copyright © 2013 Scott E. Carpenter
Traffic Simulation Challenges • Key challenges: 1. Specifications of APIs for coupling traffic flow and networking simulators 2. Modeling how drivers react to the additional information provided by VANETs 3. Benchmark definitions to make simulation studies and results comparable 4. Since traffic flow simulators do not typically model accidents, accident models may also be needed to represent real world vehicular dynamics.
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Signal Modeling •
Key challenges: • Channel conditions • Nakagami-m distribution was proposed to cover a wide range of potential channel conditions • Environmental factors (difficult to capture, often ignored in simulation) • • •
Weather Surrounding buildings Traffic •
e.g. large scale fading
• Receiver capability modeling • Capture is a highly important capability for dealing with the one-channel problem • Modern chipsets are able to capture packets almost independently of the order of their arrival. • Network simulators often only provide less powerful capturing capabilities that do not correspond to modern chipsets.
• Benchmarks • With respect to simulation methodology, a set of standardized benchmarks and test scenarios would be useful to make protocol and model proposals comparable with each other. 47
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Networking Simulation Architecture
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Simulation Results •
Scenarios: •
Open-air, static vehicles •
• •
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Control channel saturated for safety-critical applications when the total offered traffic approached 1000 packets per second (see chart)
Urban setting (Washington, D. C.) Highway setting
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Simulation Results (2) •
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Ideal RSU spacing: 1000 – 1500 m
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Other Challenges • • • • • • • • • • • • 51
Data filtering and aggregation Fast and proper distribution Hardware/software compatibility Node densities Data security Distribution range Relative speed Mobility and handover Frame error rate Quality of service Hidden nodes Radio channel characteristics Copyright © 2013 Scott E. Carpenter
Conclusions and Next Steps • IVC research remains very active • Google Scholar search for “VANET” yields 852 articles thus far in 2013, 2048 articles in 2012. • Only a few trials active in U.S.
• Standards seem in place • IEEE 802.11p • IEEE 1609 • SAE J2735
• Simulation remains primary means for evaluation of ideas • Difficult to capture many “real world” issues
• Many research opportunities remain in IVC. 52
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Backup Slides
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References References [1] IEEE, 1609 WG – Dedicated Short Range Communication Working Group. [Online:] http://standards.ieee.org/develop/wg/1609_WG.html. [Accessed: 4 Jun 2013] [2] Wikipedia, IEEE 802.11p, [Online:] http://en.wikipedia.org/wiki/IEEE_802.11p, [Accessed: 4 June 2013]. [3] H. Hartenstein and K. Laberteaux, A Tutorial Survey on Vehicular Ad Hoc Networks, IEEE Communications Magazine 164:171, June 2008. [4] V. Rani and R. Dhir, A Study of Ad-Hoc Network: A Review, Journal of Advanced Research in Computer Science and Software Engineering Vol. 3 Issue 3 135:138, Mar 2013. [5] S. Gräfling et. al. Performance Evaluation of IEEE 1609 WAVE and IEEE 802.11p for Vehicular Communications, ICUFN 978-1-4244-8086-9/10 344:348, 2010. [6] Research and Innovative Technology Assistance (RITA), IEEE 1609 - Family of Standards for Wireless Access in Vehicular Environments (WAVE), U.S. Department of Transportation, [Online: ] http://www.standards.its.dot.gov/Factsheets/Factsheet/80, [Accessed: 6 Jun 2013]. [7] IEEE, P1609.0/D5 Draft Guide for WAVE Architecture, IEEE, 2012. [8] U. Özgüner, A. Tankut, and K. Redmill. Autonomous ground vehicles. Artech House, 2011. [9] W. Williams, Google’s self-driving cars gather nearly 1GB of sensor data every second – would you trust them? Betanews [Online]. http://betanews.com/2013/05/02/googles-self-driving-cars-gather-nearly-1gb-of-sensordata-every-second-would-you-trust-them/ [Accessed: June 1, 2013] [10] M.S. Javadi, S. Habib and M.A. Hannon, Survey on Inter-Vehicle Communications Applications: Current Trends and Challenges, Information Technology Journal, 12.2: 243-250, 2013. [11] S. Habib et. al., Inter-Vehicle Wireless Communications Technologies, Issues, and Challenges, Information Technology Journal, ISSN 1812-5638 / DOI: 10.3923/itj.2013, 2013. [12] C. Campolo and A. Molinaro, Design Challenges and Solutions for Multi-channel Communications in Vehicular Ad Hoc NETworks, J. Zheng et al. (Eds.): Adhocnets 2012, LNICST 111, pp. 289–301, 2013. [13] IEEE, IEEE Std 1609.2-2013 - IEEE Standard for Wireless Access in Vehicular Environments—Security Services for Applications and Management Messages, 26 Apr 2013. [14] SAE, DSRC Implementation Guide – A guide to users of SAE J2735 message sets over DSRC, SAE International, 16 Feb 2010. 54 Copyright © 2013 Scott E. Carpenter
References (2) References [15] IEEE, IEEE Std 1609.1-2006 - IEEE Trial-Use Standard for Wireless Access in Vehicular Environments (WAVE) - Resource Manager, 13 Oct 2006. [16] IEEE, IEEE Std 1609.3-2010 - IEEE Standard for Wireless Access in Vehicular Environments (WAVE) Networking Services, 30 Dec 2010. [17] Anonymous, Transportation of the United States, nationalatlas.gov [Online:] http://nationalatlas.gov/transportation.html [Accessed: 7 Jun 2013]. [18] Research and Innovative Technology Assistance (RITA), Table 1-11: Number of U.S. Aircraft, Vehicles, Vessels, and Other Conveyances, U.S. Department of Transportation, [Online: ] http://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/national_transportation_statistics/html/table_0 1_11.html, [Accessed: 7 Jun 2013]. [19] Federal Highway Administration, Manual on Uniform Traffic Control Devices (MUTCD) – Frequently Asked Questions – Part 4 – Highway Traffic Signals, U.S. Department of Transportation, [Online:] http://mutcd.fhwa.dot.gov/knowledge/faqs/faq_part4.htm, [Accessed 7 Jun 2013]. [20] A. Smith, Smartphone Ownership 2013, Pew Research, 5 Jun 2013, [Online:] http://www.pewinternet.org/Reports/2013/Smartphone-Ownership-2013/Findings.aspx, [Accessed: 7 Jun 2013]. [21] IEEE, IEEE Std 1609.4-2010 - IEEE Standard for Wireless Access in Vehicular Environments (WAVE) - Multichannel Operation, 7 Feb 2011. [22] P. Farradyne, Vehicle Infrastructure Integration (VII): VII Architecture and Functional Requirements – Version 1.1, ITS Joint Program Office, U.S. Department of Transportation, 20 Jul 2005. [23] Wikipedia, Vehicle infrastructure integration, [Online:] http://en.wikipedia.org/wiki/Vehicle_infrastructure_integration, [Accessed: 7 June 2013]. [24] Research and Innovative Technology Assistance (RITA), Final Report: Vehicle Infrastructure Integration (VII) Proof of Concept (POC) Test – Executive Summary, U.S. Department of Transportation, Feb 2009. [25] Research and Innovative Technology Assistance (RITA), ITS Research Fact Sheets, U.S. Department of Transportation, [Online: ] http://www.its.dot.gov/factsheets/overview_factsheet.htm, [Accessed: 7 Jun 2013].
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References (3) References [26] M. Felice, L. Bedogni, and L. Bononi, Group communication on highways: An evaluation study of geocast protocols and applications, Ad Hoc Networks 11 (2013) 818-832, 2012. [27] M. Farooq et. al., Integration of Vehicular Roadside Access and the Internet: Challenges & a Review of Strategies, Devices, Circuits and Systems (ICDCS), 2012 International Conference on. IEEE, 2012.
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