Contents:
1. Introduction & Scope
2. End-to-End deployments
3. Day One Messages
4. WAVE protocol
5. Hardware
6. Security
Ch 1: Intro
The goal of this guidance is to serve as a straightforward reference for ‘Day One’ 5.9 GHz channel 183 Long-Term-Evolution (LTE)-V2X deployment considerations and requirements in the United States.
LTE-V2X = CV2X = all technologies under 3GPP. Includes direct (PC5) | mobile network communication (Uu)
Sets expectations of safe traffic communication needs
Identify a set of important messages for interoperability needs
Provide SAE 3161 communication profiles for level-setting channel access and rules.
Ch 3: Day one messages
Categories:
1. Mass use production vehicle (MUPV)
Private vehicles
2. Limited use fleet vehicle (LUFV)
Company vehicles
Agency vehicles
3. Limited use mixed vehicle (LUMV)
Subset of MUPV and LUFV
Messages for MUPV
1. Basic safety message (BSM)
Potential crash threats
Alert drivers if necessary
Applies to class 1-7. (8-13 – Day 2 messages)
2. Signal Phase and Timing (SPAT)
Current / future signal status
Timing of each of the lanes approaching the signalized intersection
3. Map Data (MAP)
Lane geometry (Width / curvature)
Speed allowed maneuvers at late connections
Main focus – signalized intersection
No elevation information? Is it important?
4. Radio Technical Commission for Maritime Services (RTCM) Corrections
Use local GNSS system for location corrections
Examples:
US – GPS
EU – Galileo
China – BeiDou Navigation System (BDS)
Russian Federation – GLONAS
Useful particularly for vehicle lane identification for Red-Light Violation Warning (RLVW)
5. Traveler Information Message (TIM);
Advisory content
Example
Road Speed
Work Zone
Road sign
School zone
Midblock crossing
6. Road Safety Message (RSM)
Evolution of TIMCurve & Work zone speeds
Lane closure
Incidents
Messages for LUFV
1. Signal Request Messages (SRM)
For the following to request preferential treatment
Emergency
Transit
Road maintenance
Others determined by local IOO (Infrastructure owner operator)
2. Signal Status Message (SSM)
Know the status of the SRM from the infrastructure
Messages for LUMV
1. Toll Advertisement Message (TAM)
Toll information
Toll point data like toll fee.
Toll geometry information
Toll vehicle acceptance message?
2. Toll Usage Message (TUM)
Initiate transaction
CV to CI
Contains information about the toll to be charged.
3. Toll Usage Message Acknowledgement (TUMack)
CI to CV
Message that acknowledges toll point data has been received and verified signature.
4. WAVE service advertisement (WSA)
Advertise services
No more information provided
Ch 4: WAVE – Wireless access of vehicular Network
LTE-V2X protocol stack as shown in Figure 1 is a combination of standards laid down in IEEE 1609, SAE 3161, 3GPP Release 14 other than that for the V2X application layer.
Figure 1: LTE-V2X Protocol Stack
1. Day 1 message Report
‘Payload Format Definition’, which is the abstract syntax notation that the message payload file has been written in the appropriate programming language; and the ‘Payload Content’, which is the message that would include some aspects such as:
Address required,
Data,
Data accuracy,
Transmission behavior, etc.
The above needs to have been defined for a message to be acceptable as a Day-One message. Standards SAE J2735, SAE J2945, SAE J3161, CTI4501, and SAE J3217 define the above two for the Da-one messages described in Ch3.
2. SAE J3161 report
J3161 provides the following for LTE-V2X communication as specified in 3GPP Release 14.
Design elements
PC5 sidelink profiles
Communication parameters
LTE communication parameters are provided for each DAY 1 message in Table 5 of the document and the following settings are defined:
PSID value: Provider service identifier indicates application service or the source (like vehicles or roadside infrastructure) of the message that is supposed to be received by a node in the IOT or the V2X context.
Layer -2 ID: Layer -2 ID refers to the data link layer (in the OSI model framework). It is responsible for the node-to-node data transfer. Destination Layer-2 ID specifically identifies the intended recipient of a message or data packet at Layer 2.
3. Channel identifier: All LTE-V2X messages are transmitted on channel 183.
4. Traffic family: Guides the priority of a message.
Critical V2V
Essential V2V
Critical I2V
Essential I2V
Critical V2I
Transactional V2I
Transactional I2V
5. PPPP: ProSe Pre-Packet Priority is the priority assigned to a message. The smaller the number the greater the priority. This is in line with the Traffic family.
6. PDB: Packet delay budget is the maximum delay the message can tolerate before transmission (usually 50/100 ms).
7. CR Limit: Channel occupancy Ratio Limit guides how much of the channel a message can occupy.
8. Transmit power level: Maximum power to be used by a transmitter to transmit a message. Typically measured in decibels (dBm), which is a logarithmic scale that expresses power levels relative to 1 milliwatt (mW). 0 dBm equals 1 mW, and 10 dBm equals 10 mW. The higher the power the longer the range.
IEEE 1602 report
SAE J3161 defines the base design elements hence all IEEE standards adhere to it to maintain interoperability. The document provides a speculative settings profile summarized below:
1. WSAs should always include:
· 3D location with the location of the antenna
· Time confidence
· IEEE 1609.2 signature
2. Security profile as per IEEE 1609.3 corrigendum
3. WSA sent < 1Hz frequency
4. Full certificate attached to it
5. RSU transmitting WSA should disable the t5000 timer or set it to largest supported value
6. PSID set at the decimal value of 134.
Chapter 6: Security
Using a Public Key Infrastructure
CA: Certificate Authority - Issues certificates that are cryptographically signed
SCMS: Security Credential Management System contains all CAs, Certificate Policies (CP) and operational functions adhered by service providers audited by a third party.
The private key obtained for every public key must be stored in secured locations in a:
HSM: Hardware Safety Module
VHSM: Virtual Hardware Safety Module
All receiving devices of public and private key pairs need to have a certificate from an issuing CA.
Contains (not limited to):
PSID (Provider Service ID): Informs the kind of message allowed to be sent by the device.
SSP (Service Specific Permission): Additional authorizations required by public vehicles
This certificate is validated by the receiver receiving a message.
Ensures:
Trusted source
No tampering during transmission
Renewal of certificates
Certificates are valid only within a defined time for enhanced security reasons.
Concurrent certificates are downloaded in a "batch" and relevant certificates are used for their valid time.
Types
Private vehicles: Pseudonym certificates
Fleet vehicles: Identification certificates
Malpractice avoidance
A sender’s certificates can be revoked by adding them to the Certificate Revocation List
When the sender is found to be sending "incorrect data". (No definition of 'incorrect provided)
A new certificate issued only after remediation
Certification Entities:
Omni Air consortium - Document 753-OA-CertScope-Matrixes
Scope,
Process,
Components and
Test specifications
Message conformance test procedure (1st 2 essential for Day One messages)
Component conformance: Validates message payload meets format requirements
Integrated system conformance: Validates message payload meets performance requirements
Maintenance conformance: Periodic validation of deployed integrated system
Misbehavior Reporting
SAE J3287 -
The standard for V2X Misbehavior reporting,
Currently under development (Check)
IEEE 1609.2 Informs about the indicators that certificates are or are not revoked through
Informs on an indicator in the certificate that is not revoked. When an end entity is found to be misbehaving this indicator is added to the reissued certificate.
Circulating a Certificate Revocation List to all the end users to cross-check the sender signature against it.
Annex B - Day 2 messages
Day 2 messages will support
Expanded Day 1 messages - BSM
Expand to vehicles over Class 7
New messages
Misbehavior reports
CRL - Certificate Revocation List
PSM - Personal safety message for VRU (vulnerable road users)
SDSM - Sensor Data Sharing Message for Cooperative perception
Under Development
RGA - Road Geometry Attributes like MAP
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