Commission Implementing Regulation (EU) 2016/799Show full title

5.4 DSRC Protocol requirements for RTM U.K.

5.4.1 Overview U.K.

DSC_34 The transaction protocol to download the Data across the 5.8 GHz DSRC interface link shall be according to the following steps. This section describes a transaction flow under ideal conditions without retransmissions or communication interrupts. U.K.

NOTE The purpose of the initialisation phase (Step 1) is to set up the communication between the REDCR and DSRC-VUs that have entered the 5.8 GHz DSRC (master-slave) transaction zone but have not yet established communication with the REDCR, and to notify the application processes. U.K.

— Step 1

Initialisation. The REDCR sends a frame containing a ‘beacon service table’ (BST) that includes the application identifiers (AIDs) in the service list that it supports. In the RTM application this will simply be the service with the AID value = 2 (Freight&Fleet). The DSRC-VU evaluates the received BST, and shall respond (see below) with the list of the supported applications within the Freight&Fleet domain, or shall not respond if none are supported. If the REDCR does not offer AID=2, the DSRC-VU shall not answer to the REDCR.

— Step 2

The DSRC-VU sends a frame containing a request for a private window allocation.

— Step 3

The REDCR sends a frame containing a private window allocation.

— Step 4

The DSRC-VU uses the allocated private window to send a frame containing its vehicle service table (VST). This VST includes a list of all the different application instantiations that this DSRC-VU supports in the framework of AID=2. The different instantiations shall be identified by means of uniquely generated EIDs, each associated with an Application Context Mark parameter value indicating the application and standard supported.

— Step 5

Next the REDCR analyses the offered VST, and either terminates the connection (RELEASE) since it is not interested in anything the VST has to offer (i.e. it is receiving a VST from a DSRC-VU that is not supporting the RTM transaction), or, if it receives an appropriate VST it starts an app instantiation.

— Step 6

To bring this about, the REDCR shall send a frame containing a command to retrieve the RTM data, identifying the RTM application instantiation by specifying the identifier corresponding to the RTM application instantiation (as specified by the DSRC-VU in the VST), and shall allocate a private window.

— Step 7

The DSRC-VU uses the newly allocated private window to send a frame that contains the addressed identifier corresponding to the RTM application instantiation as provided in the VST, followed by the attribute RtmData (payload element + security element).

— Step 8

If there are multiple services requested, the value ‘n’ is changed to the next service reference number and the process repeated.

— Step 9

The REDCR confirms receipt of the data by sending a frame containing a RELEASE command to the DSRC-VU to terminate the session OR if it has failed to validate a successful receipt of the LDPU goes back to step 6.

See Figure 14.6 for a pictorial description of the transaction protocol.

Figure 14.6

RTM over 5,8 GHz DSRC process flow

5.4.2 Commands U.K.

DSC_35 The following commands are the only functions used in an RTM transaction phase U.K.

— INITIALISATION.request

:

A command, issued from the REDCR in the form of a broadcast with definition of applications that the REDCR supports.

— INITIALISATION.response

:

An answer from the DSRC-VU confirming the connection and containing a list of supported application instances with characteristics and information how to address them (EID).

— GET.request

:

A command, issued from the REDCR to the DSRC-VU, that specifies the application instantiation to be addressed by means of a defined EID, as received in the VST, instructing the DSRC-VU to send the selected attribute(s) with the Data. The objective of the GET command is for the REDCR to obtain the Data from the DSRC-VU.

— GET.response

:

An answer from the DSRC-VU that contains the Data requested.

— ACTION.request ECHO

:

A command, instructing the DSRC-VU to send back data from the DSRC-VU to the REDCR. The objective of the ECHO command is to enable workshops or type approval test facilities to test that the DSRC link is working without needing access to security credentials.

— ACTION.response ECHO

:

An answer from the DSRC VU on the ECHO command.

— EVENT_REPORT.request RELEASE

:

A command, instructing the DSRC-VU that the transaction is ended. The objective of the RELEASE command is to end the session with the DSRC-VU. On receipt of the RELEASE the DSRC-VU shall not respond to any further interrogations under the current connection. Note that according to EN 12834 a DSRC-VU will not connect twice to the same interrogator unless it has been out of the communication zone for 255 seconds or if the Beacon ID of the interrogator is changed.

5.4.3 Interrogation command sequence U.K.

DSC_36 From the perspective of the command and response sequence, the transaction is described as follows: U.K.

Sequence	Sender		Receiver	Description	Action
1	REDCR	>	DSRC-VU	Initialisation of the communication link — Request	REDCR broadcasts BST
2	DSRC-VU	>	REDCR	Initialisation of the communication link — Response	If BST supports AID=2 then DSRC-VU Requests a private window
3	REDCR	>	DSRC-VU	Grants a private window	Sends Frame containing private window allocation
4	DSRC-VU	>	REDCR	Sends VST	Sends Frame comprising VST
5	REDCR	>	DSRC-VU	Sends GET.request for data in Attribute for specific EID
6	DSRC-VU	>	REDCR	Sends GET.response with requested Attribute for specific EID	Sends Attribute (RTMData, OWSData….) with data for specific EID
[F1 7	REDCR	>	DSRC-VU	Sends GET.request for data of other Attribute (if appropriate)	]
8	DSRC-VU	>	REDCR	Sends GET.response with requested Attribute	Sends Attribute with data for specific EID
9	REDCR	>	DSRC-VU	Acknowledges successful receipt of data	Sends RELEASE command which closes transaction
10	DSRC-VU			Closes transaction

An example of the transaction sequence and contents of the exchanged frames is defined in clauses 5.4.7 and 5.4.8

5.4.4 Data structures U.K.

DSC_37 The semantic structure of the Data when passed across the 5.8 GHz DSRC interface shall be consistent with what described in this Appendix. The way these data are structured is specified in this clause. U.K.

DSC_38 The payload (RTM data) consists of the concatenation of U.K.

1.

EncryptedTachographPayload data, which is the encryption of the TachographPayload defined in ASN.1 in section 5.4.5. The method of encryption is described in Appendix 11

2.

DSRCSecurityData, specified in Appendix 11.

DSC_39 The RTM Data is being addressed as RTM Attribute=1 and is transferred in the RTM container = 10. U.K.

DSC_40 The RTM Context Mark shall identify the supported standard part in the TARV series of standards (RTM corresponds to Part 9) U.K.

The ASN.1 module definition for the DSRC data within the RTM application is defined as follows:

5.4.5 Elements of RtmData, actions performed and definitions U.K.

DSC_41 The data values to be calculated by the VU and used to update the secured data in the DSRC-VU shall be calculated according to the rules defined in Table 14.3: U.K.

Table 14.3
Elements of RtmData, actions performed and definitions
(1) RTM Data Element	(2) Action performed by the VU		(3) ASN.1 definition of data
RTM1 Vehicle Registration Plate	The VU shall set the value of the tp15638VehicleRegistrationPlate data element RTM1 from the recorded value of the data type VehicleRegistrationIdentification as defined in Appendix 1 VehicleRegistrationIdentification	Vehicle Registration Plate expressed as a string of characters
RTM2 Speeding Event	The VU shall generate a boolean value for data element RTM2 tp15638SpeedingEvent. The tp15638SpeedingEvent value shall be calculated by the VU from the number of Over Speeding Events recorded in the VU in the last 10 days of occurrence, as defined in Annex 1C. If there is at least one tp15638SpeedingEvent in the last 10 days of occurrence, the tp15638SpeedingEvent value shall be set to TRUE. ELSE if there are no events in the last 10 days of occurrence, the tp15638SpeedingEvent shall be set to FALSE.	1 (TRUE) — Indicates irregularities in speed within last 10 days of occurrence
RTM3 Driving Without Valid Card	The VU shall generate a boolean value for data element RTM3 tp15638DrivingWithoutValidCard. The VU shall assign a value of True to the tp15638DrivingWithoutValidCard variable if the VU data has recorded at least one event in the last 10 days of occurrence of type ‘Driving without an appropriate card’ event as defined in Annex 1C. ELSE if there are no events in the last 10 days of occurrence, the tp15638DrivingWithoutValidCard variable shall be set to FALSE.	1 (TRUE) = Indicates invalid card usage
RTM4 Valid Driver Card	The VU shall generate a boolean value for data element RTM4 tp15638DriverCard on the basis of the data stored in the VU and defined in Appendix 1. If no valid driver card is present the VU shall set the variable to TRUE ELSE if a valid driver card is present the VU shall set the variable to FALSE	0 (FALSE) = Indicates a valid driver card
RTM5 Card Insertion while Driving	The VU shall generate a boolean value for data element RTM5. The VU shall assign a value of TRUE to the tp15638CardInsertion variable if the VU data has recorded in the last 10 days of occurrence at least one event of type ‘Card insertion while driving.’ as defined in Annex 1C. ELSE if there are no such events in the last 10 days of occurrence, the tp15638CardInsertion variable shall be set to FALSE.	1 (TRUE) = Indicates card insertion while driving within last 10 days of occurrence
RTM6 Motion Data Error	The VU shall generate a boolean value for data element RTM6. The VU shall assign a value of TRUE to the tp15638MotionDataError variable if the VU data has in the last 10 days of occurrence recorded at least one event of type ‘Motion data error’ as defined in Annex 1C. ELSE if there are no such events in the last 10 days of occurrence, the tp15638MotionDataError variable shall be set to FALSE.	1 (TRUE) = Indicates motion data error within last 10 days of occurrence
RTM7 Vehicle Motion Conflict	The VU shall generate a boolean value for data element RTM7. The VU shall assign a value of TRUE to the tp15638vehicleMotionConflict variable if the VU data has in the last 10 days recorded at least one event of type Vehicle Motion Conflict (value ‘0A’H ). ELSE if there are no events in the last 10 days of occurrence, the tp15638vehicleMotionConflict variable shall be set to FALSE.	1 (TRUE) = Indicates motion conflict within last 10 days of occurrence
RTM8 2nd Driver Card	The VU shall generate a boolean value for data element RTM8 on the basis of Annex 1C (‘Driver Activity Data’ CREW and CO-DRIVER). If a 2nd valid driver card is present the VU shall set the variable to TRUE ELSE if a 2nd valid driver card is not present the VU shall set the variable to FALSE	1 (TRUE) = Indicates a second driver card inserted
RTM9 Current Activity	The VU shall generate a boolean value for data element RTM9. If the current activity is recorded in the VU as any activity other than ‘DRIVING’ as defined in Annex 1C the VU shall set the variable to TRUE ELSE if the current activity is recorded in the VU as ‘DRIVING’ the VU shall set the variable to FALSE	1 (TRUE) = other activity selected; 0 (FALSE) = driving selected
RTM10 Last Session Closed	The VU shall generate a boolean value for data element RTM10. If the last card session was not properly closed as defined in Annex 1C the VU shall set the variable to TRUE. ELSE if the last card session was properly closed the VU shall set the variable to FALSE	1 (TRUE) = improperly closed 0 (FALSE) = properly closed
RTM11 Power Supply Interruption	The VU shall generate an integer value for data element RTM11. The VU shall assign a value for the tp15638PowerSupplyInterruption variable equal to the longest power supply interruption according to Article 9, Reg (EU) 165/2014 of type ‘Power supply interruption’ as defined in Annex 1C. ELSE if in the last 10 days of occurrence there are have been no Power supply interruption events the value of the integer shall be set to 0.	— Number of power supply interruptions in last 10 days of occurrence
[F1 RTM12 Sensor Fault	The VU shall generate an integer value for data element RTM12. The VU shall assign to the variable sensorFault a value of: 1 if an event of type ‘ 35H ’ Sensor fault has been recorded in the last 10 days, 2 if an event of type GNSS receiver fault (either internal or external with enum values ‘ 36’H or ‘37 ’ H) has been recorded in the last 10 days. 3 if an event of type ‘ 0E ’ H Communication error with the external GNSS facility event has been recorded in the last 10 days. 4 If both Sensor Fault and GNSS receiver faults have been recorded in the last 10 days 5 If both Sensor Fault and Communication error with the external GNSS facility event have been recorded in the last 10 days 6 If both GNSS receiver fault and Communication error with the external GNSS facility event have been recorded in the last 10 days 7 If all three sensor faults, have been recorded in the last 10 days ELSE it shall assign a value of 0 if no events have been recorded in the last 10 days	– sensor fault one octet as per data dictionary	]
RTM13 Time Adjustment	The VU shall generate an integer value (timeReal from Appendix 1) for data element RTM13 on the basis of the presence of Time Adjustment data as defined in Annex 1C. The VU shall assign the value of time at which the last time adjustment data event has occurred. ELSE if no ‘Time Adjustment’ event. as defined in Annex 1C is present in the VU data it shall set a value of 0	Time of the last time adjustment
RTM14 Security Breach Attempt	The VU shall generate an integer value (timeReal from Appendix 1) for data element RTM14 on the basis of the presence of a Security breach attempt event as defined in Annex 1C. The VU shall set the value of the time of the latest security breach attempt event recorded by the VU. ELSE if no ‘security breach attempt’ event as defined in Annex 1C is present in the VU data it shall set a value of 0x00FF.	Time of last breach attempt — Default value =0x00FF
RTM15 Last Calibration	The VU shall generate an integer value (timeReal from Appendix 1) for data element RTM15 on the basis of the presence of Last Calibration data as defined in Annex 1C. The VU shall set the value of time of the latest two calibrations (RTM15 and RTM16), which are set in VuCalibrationData defined in Appendix 1. The VU shall set the value for RTM15 to the timeReal of the latest calibration record.	Time of last calibration data
RTM16 Previous Calibration	The VU shall generate an integer value (timeReal from Appendix 1) for data element RTM16 of the calibration record preceding that of the last calibration ELSE if there has been no previous calibration the VU shall set the value of RTM16 to 0.	Time of previous calibration data
RTM17 Date Tachograph Connected	For data element RTM17 the VU shall generate an integer value (timeReal from Appendix 1). The VU shall set the value of the time of the initial installation of the VU. The VU shall extract this data from the VuCalibrationData (Appendix 1) from the vuCalibrationRecords with CalibrationPurpose equal to: ‘03’H	Date tachograph connected
RTM18 Current Speed	The VU shall generate an integer value for data element RTM18. The VU shall set the value for RTM16 to the last current recorded speed at the time of the latest update of the RtmData.	Last current recorded speed
RTM19 Timestamp	For data element RTM19 the VU shall generate an integer value (timeReal from Appendix 1). The VU shall set the value for RTM19 to the time of the latest update of the RtmData.	Timestamp of current TachographPayload record

5.4.6 Data transfer mechanism U.K.

DSC_42 Payload data defined previously are requested by the REDCR after initialisation phase, and consequently transmitted by the DSRC-VU in the allocated window. The command GET is used by the REDCR to retrieve data. U.K.

[F1 DSC_43 For all DSRC exchanges, data shall be encoded using PER (Packed Encoding Rules) UNALIGNED, apart from and , which shall be encoded using OER (Octet Encoding Rules) defined in ISO/IEC 8825-7, Rec. ITU-T X.696.] U.K.

5.4.7 Detailed DSRC transaction description U.K.

DSC_44 Initialisation is performed according to DSC_44 — DSC_48 and Tables 14.4 — 14.9. In the initialisation phase, the REDCR starts sending a frame containing a BST (Beacon Service Table) according to EN 12834 and EN 13372, 6.2, 6.3, 6.4 and 7.1 with settings as specified in the following Table 14.4. U.K.

Table 14.4
Initialisation — BST frame settings
Field	Settings
Link Identifier	Broadcast address
BeaconId	As per EN 12834
Time	As per EN 12834
Profile	No extension, 0 or 1 to be used
MandApplications	No extension, EID not present, Parameter not present, AID= 2 Freight&Fleet
NonMandApplications	Not present
ProfileList	No extension, number of profiles in list = 0
Fragmentation header	No fragmentation
Layer 2 settings	Command PDU, UI command

A practical example of the settings specified in Table 14.4, with an indication of bit encodings, is given in the following Table 14.5.

Table 14.5
Initialisation — BST frame contents example
Octet #	Attribute/Field	Bits in octet	Description
1	FLAG		Start flag
2	Broadcast ID		Broadcast address
3	MAC Control Field		Command PDU
4	LLC Control field		UI command
5	Fragmentation header		No fragmentation
6	BST		Initialisation request
	SEQUENCE {
	OPTION indicator BeaconID SEQUENCE { ManufacturerId INTEGER (0..65535)		NonMand applications not present
			Manufacturer Identifier
7
8
	IndividualID INTEGER (0..134217727) }		27 bit ID available for manufacturer
9
10
11
12	Time INTEGER (0..4294967295)		32 bit UNIX real time
13
14
15
16	Profile INTEGER (0..127,...)		No extension. Example profile 0
17	MandApplications SEQUENCE (SIZE(0..127,...)) OF {		No extension, Number of mandApplications = 1
18	SEQUENCE {
	OPTION indicator		EID not present
	OPTION indicator		Parameter not present
	AID DSRCApplicationEntityID } }		No extension. AID= 2 Freight&Fleet
19	ProfileList SEQUENCE (0..127,...) OF Profile }		No extension, number of profiles in list = 0
20	FCS		Frame check sequence
21
22	Flag		End Flag

DSC_45 A DSRC-VU, when receiving a BST, requires the allocation of a private window, as specified by EN 12795 and EN 13372, 7.1.1, with no specific RTM settings. Table 14.6 provides an example of bit encoding. U.K.

Table 14.6
Initialisation — Private window allocation request frame contents
Octet #	Attribute/Field	Bits in octet	Description
1	FLAG		Start flag
2	Private LID		Link address of specific DSRC-VU
3
4
5
6	MAC Control field		Private window request
7	FCS		Frame check sequence
8
9	Flag		End Flag

DSC_46 The REDCR then answers by allocating a private window, as specified by EN 12795 and EN 13372, 7.1.1 with no specific RTM settings. U.K.

Table 14.7 provides an example of bit encoding.

Table 14.7
Initialisation — Private window allocation frame contents
Octet #	Attribute/Field	Bits in octet	Description
1	FLAG		Start flag
2	Private LID		Link address of the specific DSRC-VU
3
4
5
6	MAC Control field		Private window allocation
7	FCS		Frame check sequence
8
9	Flag		End Flag

DSC_47 The DSRC-VU, when receiving the private window allocation, sends its VST (Vehicle Service Table) as defined in EN 12834 and EN 13372, 6.2, 6.3, 6.4 and 7.1 with settings as specified Table 14.8, using the allocated transmission window. U.K.

Table 14.8
Initialisation — VST frame settings
Field	Settings
Private LID	As per EN 12834
VST parameters	Fill=0, then for each supported application: EID present, parameter present, AID=2, EID as generated by the OBU
Parameter	No extension, Contains the RTM Context Mark
ObeConfiguration	The optional ObeStatus field may be present, but shall not be used by the REDCR
Fragmentation header	No fragmentation
Layer 2 settings	Command PDU, UI command

DSC_48 The DSRC-VU shall support the ‘Freight and Fleet’ application, identified by the Application Identifier ‘2’. Other Application Identifiers may be supported, but shall not be present in this VST, as the BST only requires AID=2. The ‘Applications’ field contains a list of the supported application instances in the DSRC-VU. For each supported application instantiation, a reference to the appropriate standard is given, made of an Rtm Context mark, which is composed of an OBJECT IDENTIFIER representing the related standard, its part (9 for RTM) and possibly its version, plus an EID that is generated by the DSRC-VU, and associated to that application instance. U.K.

A practical example of the settings specified in Table 14.8, with an indication of bit encodings, is given in Table 14.9.

Table 14.9
Initialisation — VST frame contents example
Octet #	Attribute/Field	Bits in octet	Description
1	FLAG		Start flag
2	Private LID		Link address of the specific DSRC-VU
3
4
5
6	MAC Control field		Command PDU
7	LLC Control field		UI command
8	Fragmentation header		No fragmentation
9	VST SEQUENCE {		Initialisation response
	Fill BIT STRING (SIZE(4))		Unused and set to 0
10	Profile INTEGER (0..127,...) Applications SEQUENCE OF {		No extension. Example profile 0
11			No extension, 1 application
12	SEQUENCE {
	OPTION indicator		EID present
	OPTION indicator		Parameter present
	AID DSRCApplicationEntityID		No extension. AID= 2 Freight&Fleet
13	EID Dsrc-EID		Defined within the OBU and identifying the application instance.
14	Parameter Container {		No extension, Container Choice = 02, Octet string
15			No extension, Rtm Context Mark length = 8
16	Rtm-ContextMark::= SEQUENCE { StandardIdentifier standardIdentifier		[F1 Object Identifier of the supported standard, part, and version. Example: ISO (1) Standard (0) TARV (15638) part9 (9) Version1 (1). First octet is 06H, which is the Object Identifier. Second octet is 06H, which is its length. Subsequent 6 octets encode the example Object Identifier.]
17
18
19
20
21
22
23
24	ObeConfiguration Sequence {
	OPTION indicator		ObeStatus not present
	EquipmentClass INTEGER (0..32767)
25
26	ManufacturerId INTEGER (0..65535)		Manufacturer identifier for the DSRC-VU as described in ISO 14816 Register
27
28	FCS		Frame check sequence
29
30	Flag		End Flag

DCS_49 The REDCR then reads the data by issuing a GET command, conforming to the GET command defined in EN 13372, 6.2, 6.3, 6.4 and EN 12834, with settings as specified in Table 14.10. U.K.

Table 14.10
Presentation — GET request frame settings
Field	Settings
Invoker Identifier (IID)	Not present
Link Identifier (LID)	Link address of the specific DSRC-VU
Chaining	No
Element Identifier (EID)	As specified in the VST. No extension
Access Credentials	No
AttributeIdList	No extension, 1 attribute, AttributeID = 1 (RtmData)
Fragmentation	No
Layer2 settings	Command PDU, Polled ACn command

Table 14.11 shows an example of reading the RTM data.

Table 14.11
Presentation — Get Request frame example
Octet #	Attribute/Field	Bits in octet	Description
1	FLAG		Start flag
2	Private LID		Link address of the specific DSRC-VU
3
4
5
6	MAC Control field		Command PDU
7	LLC Control field		Polled ACn command, n bit
8	Fragmentation header		No fragmentation
9	Get.request SEQUENCE {		Get request
	OPTION indicator		Access Credentials not present
	OPTION indicator		IID not present
	OPTION indicator		AttributeIdList present
	Fill BIT STRING(SIZE(1))		Set to 0.
10	EID INTEGER(0..127,…)		The EID of the RTM application instance, as specified in the VST. No extension
11	AttributeIdList SEQUENCE OF { AttributeId }}		No extension, number of attributes = 1
12			AttributeId=1, RtmData. No extension
13	FCS		Frame check sequence
14
15	Flag		End Flag

DSC_50 The DSRC-VU, when receiving the GET request, sends a GET response with the requested data conforming to the GET response defined in EN 13372, 6.2, 6.3, 6.4 and EN 12834, with settings as specified in Table 14.12. U.K.

Table 14.12
Presentation — GET response frame settings
Field	Settings
Invoker Identifier (IID)	Not present
Link Identifier (LID)	As per EN 12834
Chaining	No
Element Identifier (EID)	As specified in the VST.
Access Credentials	No
Fragmentation	No
Layer2 settings	Response PDU, Response available and command accepted, ACn command

Table 14.13 shows an example of reading the RTM data.

Table 14.13
Presentation — Response frame contents example
Octet #	Attribute/Field	Bits in octet	Description
1	FLAG		Start flag
2	Private LID		Link address of the specific DSRC-VU
3
4
5
6	MAC Control field		Response PDU
7	LLC Control field		Response available, ACn command n bit
8	LLC Status field		Response available and command accepted
9	Fragmentation header		No fragmentation
10	Get.response SEQUENCE {		Get response
	OPTION indicator		IID not present
	OPTION indicator		Attribute List present
	OPTION indicator		Return status not present
	Fill BIT STRING(SIZE(1))		Not used
11	EID INTEGER(0..127,…)		Responding from the RTM application Instance. No extension,
12	AttributeList SEQUENCE OF {		No extension, number of attributes = 1
13	Attributes SEQUENCE { AttributeId		No extension, AttributeId=1 (RtmData)
14	AttributeValue CONTAINER {		No extension, Container Choice = 1010.
15			RtmData
16
17
…		…
n	}}}}
n+1	FCS		Frame check sequence
n+2
n+3	Flag		End Flag

DSC_51 The REDCR then closes the connection by issuing a EVENT_REPORT, RELEASE command conforming to EN 13372, 6.2, 6.3, 6.4 and EN 12834,7.3.8, with no specific RTM settings. Table 14.14 shows a bit encoding example of the RELEASE command. U.K.

Table 14.14
Termination. EVENT_REPORT Release frame contents
Octet #	Attribute/Field	Bits in octet	Description
1	FLAG		Start flag
2	Private LID		Link address of the specific DSRC-VU
3
4
5
6	MAC Control field		The frame contains a command LPDU
7	LLC Control field		UI command
8	Fragmentation header		No fragmentation
9	EVENT_REPORT.request SEQUENCE {		EVENT_REPORT (Release)
	OPTION indicator		Access Credentials not present
	OPTION indicator		Event parameter not present
	OPTION indicator		IID not present
	Mode BOOLEAN		No response expected
10	EID INTEGER (0..127,…)		No extension, EID = 0 (System)
11	EventType INTEGER (0..127,…) }		Event type 0 = Release
12	FCS		Frame check sequence
13
14	Flag		End Flag

DSC_52 The DSRC-VU is not expected to answer to the Release command. The communication is then closed. U.K.

5.4.8 DSRC Test transaction description U.K.

DSC_53 Full tests that include securing the data, need to be carried out as defined in Appendix 11 Common Security Mechanisms, by authorised persons with access to security procedures, using the normal GET command as defined above. U.K.

DSC_54 Commissioning and periodic inspection tests that require decrypting and comprehension of the decrypted data content shall be undertaken as specified in Appendix 11 Common Security Mechanisms and Appendix 9, Type Approval List of Minimum required tests. U.K.

However, the basic DSRC communication can be tested by the command ECHO. Such tests may be required on commissioning, at periodic inspection, or otherwise to the requirement of the competent control authority or Regulation (EU) No 165/2014 (See 6 below)

DSC_55 In order to effect this basic communication test, the ECHO command is issued by the REDCR during a session, i.e., after an initialisation phase has been completed successfully. The sequence of interactions is thus similar to that of an interrogation: U.K.

— Step 1

The REDCR sends a ‘beacon service table’ (BST) that includes the application identifiers (AIDs) in the service list that it supports. In the RTM applications this will simply be the service with the AID value = 2.

The DSRC-VU evaluates the received BST, and where it identifies that the BST is requesting Freight&Fleet (AID = 2), the DSRC-VU shall respond. If the REDCR does not offer AID=2, the DSRC-VU shall shut down its transaction with the REDCR.

— Step 2

The DSRC-VU sends a request for a private window allocation.

— Step 3

The REDCR sends a private window allocation.

— Step 4

The DSRC-VU uses the allocated private window to send its vehicle service table (VST). This VST includes a list of all the different application instantiations that this DSRC-VU supports in the framework of AID=2. The different instantiations shall be identified by means of uniquely EIDs, each associated with a parameter value indicating the instance of the application that is supported.

— Step 5

Next the REDCR analyses the offered VST, and either terminates the connection (RELEASE) since it is not interested in anything the VST has to offer (i.e., it is receiving a VST from a DSRC-VU that is not an RTM VU, or, if it receives an appropriate VST it starts an app instantiation.

— Step 6

The REDCR shall issue a command (ECHO) to the specific DSRC-VU, and allocates a private window.

— Step 7

The DSRC-VU uses the newly allocated private window to send an ECHO response frame.

The following tables give a practical example of an ECHO exchange session.

DSC_56 Initialisation is performed according to 5.4.7 (DSC_44 — DSC_48) and Tables 14.4 — 14.9 U.K.

DSC_57 The REDCR then issues an ACTION, ECHO command conforming to ISO 14906, containing 100 octets of data and with no specific settings for RTM. Table 14.15 shows the contents of the frame sent by the REDCR. U.K.

Table 14.15
ACTION, ECHO request frame example
Octet #	Attribute/Field	Bits in octet	Description
1	FLAG		Start flag
2	Private LID		Link address of the specific DSRC-VU
3
4
5
6	MAC Control field		Command PDU
7	LLC Control field		Polled ACn command, n bit
8	Fragmentation header		No fragmentation
9	ACTION.request SEQUENCE {		Action request (ECHO)
	OPTION indicator		Access Credentials not present
	OPTION indicator		Action parameter present
	OPTION indicator		IID not present
	Mode BOOLEAN		Response expected
10	EID INTEGER (0..127,…)		No extension, EID = 0 (System)
11	ActionType INTEGER (0..127,…)		No extension, Action type ECHO request
12	ActionParameter CONTAINER {		No extension, Container Choice = 2
13			No extension. String length = 100 octets
14			Data to be echoed
…		…
113	}}
114	FCS		Frame check sequence
115
116	Flag		End Flag

DSC_58 The DSRC-VU, when receiving the ECHO request, sends an ECHO response of 100 octets of data by reflecting the received command, according to ISO 14906, with no specific settings for RTM. Table 14.16 shows a bit level encoding example. U.K.

Table 14.16
ACTION, ECHO response frame example
Octet #	Attribute/Field	Bits in octet	Description
1	FLAG		Start flag
2	Private LID		Link address of the specific VU
3
4
5
6	MAC Control field		Response PDU
7	LLC Control field		ACn command n bit
8	LLC status field		Response available
9	Fragmentation header		No fragmentation
10	ACTION.response SEQUENCE {		ACTION response (ECHO)
	OPTION indicator		IID not present
	OPTION indicator		Response parameter present
	OPTION indicator		Return status not present
	Fill BIT STRING (SIZE (1))		Not used
11	EID INTEGER (0..127,…)		No extension, EID = 0 (System)
12	ResponseParameter CONTAINER {		No extension, Container Choice = 2
13			No extension. String length = 100 octets
14			Echoed data
…		…
113	}}
114	FCS		Frame check sequence
115
116	Flag		End Flag