ISO 24103:2009

Intelligent transport systems — Communications access for land mobiles (CALM) — Media adapted interface layer (MAIL)

ISO 24103:2009 determines the logical structure of using dedicated short-range communication (DSRC) with an OSI (open systems interconnection) application layer as a CALM medium for IP communications. DSRC to which MAIL is applicable are those with an application layer compliant with ISO 15628, and the standards of such DSRC include the following: ARIB STD-T75 DSRC (Japan); TTAS.KO-06.0025 DSRC in the 5,8 GHz band (Korea); EN 12253 DSRC physical layer using microwave in the 5,8 GHz band, EN 12795 DSRC data link layer and EN 12834 DSRC application layer (Europe).

Systèmes intelligents de transport — Accès aux communications des services mobiles terrestres (CALM) — Couche d'interface adaptée au milieu (MAIL)

General Information

• Status: Published
• Publication Date: 25-May-2009
• ICS: 03.220.01 - Transport in general
• ICS: 35.240.60 - IT applications in transport
• Technical Committee: ISO/TC 204 - Intelligent transport systems
• Drafting Committee: ISO/TC 204/WG 16 - Communications
• Current Stage: 9060 - Close of review
• Start Date: 04-Jun-2025

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 24103
First edition
2009-06-01

Intelligent transport systems —
Communications access for land mobiles
(CALM) — Media adapted interface
layer (MAIL)
Systèmes intelligents de transport — Accès aux communications des
services mobiles terrestres (CALM) — Couche d'interface adaptée au
milieu (MAIL)




Reference number
ISO 24103:2009(E)
©
ISO 2009

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ISO 24103:2009(E)
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ISO 24103:2009(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Conformance. 1
3 Normative references . 2
4 Terms and definitions. 2
5 Symbols and abbreviated terms . 2
6 Requirements . 4
6.1 Structure and operation . 4
6.2 Communication control method . 6
7 Extended link control protocol. 7
7.1 General. 7
7.2 Transmission service control. 8
7.3 Client/server communication control . 11
7.4 Communication control management . 13
8 Network control protocol . 15
8.1 General. 15
8.2 LAN control protocol. 16
8.3 Local port control protocol. 19
9 Adaptation . 19
Annex A (informative) ASN.1 definitions . 20
Annex B (informative) Relationship of primitives and protocol data units (PDU). 23
Bibliography . 24

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ISO 24103:2009(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 24103 was prepared by Technical Committee ISO/TC 204, Intelligent transport systems.

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ISO 24103:2009(E)
Introduction
This International Standard is part of a family of International Standards for CALM (communication access for
land mobiles) which determine a common architecture, network protocols and air interface definitions for
wireless communications using cellular second generation, cellular third generation, mobile wireless
broadband, microwaves, millimetre waves, infra-red communications, and so on. Other air interfaces may be
added at a later date. These air interfaces are designed for providing parameters and protocols for broadcast,
point-point, vehicle-vehicle, and vehicle-point communications in the intelligent transport systems (ITS) sector.
This International Standard determines the media adapted interface layer (MAIL), which enables
communication media such as dedicated short-range communication (DSRC) compliant with ISO 15628
(DSRC application layer) to be used as CALM media for internet protocol (IP)-based communications.
DSRC media with the following characteristics are available.
⎯ Proven radio communication for ITS:
1) direct communication based on ISO 15628, e.g. for electronic fee collection (EFC) — in ARIB
STD-T75, a 4 MB/s data rate and a communication zone of approximately 30 m, available for
response during high-speed driving;
2) practical experiments for IP communication over the ISO 15628 application layer — a DSRC
application sub-layer (ARIB STD-T88) that works on application ID 18 of ISO 15628.
⎯ Communication in a comparatively small communication zone:
1) easy identification of a communication partner;
2) reuse frequency in every small zone and effective utilization of frequency resources;
3) less liable to be affected by shadowing.

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INTERNATIONAL STANDARD ISO 24103:2009(E)

Intelligent transport systems — Communications access for
land mobiles (CALM) — Media adapted interface layer (MAIL)
1 Scope
This International Standard determines the logical structure of using dedicated short-range communication
(DSRC) with an OSI (open systems interconnection) application layer as a CALM medium for IP
communications. DSRC to which MAIL is applicable are those with an application layer compliant with
ISO 15628, and the standards of such DSRC include the following:
⎯ ARIB STD-T75 DSRC (Japan);
⎯ TTAS.KO-06.0025 DSRC in the 5,8 GHz band (Korea);
⎯ EN 12253 DSRC physical layer using microwave in the 5,8 GHz band, EN 12795 DSRC data link layer
and EN 12834 DSRC application layer (Europe).
Figure 1 shows the architecture of the MAIL, which can be considered as a specific extension of the
communication adaptation layer (CAL) specified by ISO 21218.
Applications
ISO 21210 CALM network layer
ISO 24103 CALM MAIL
DSRC with ISO 15628-
compliant L7

NOTE In furnishing additional information on CALM MAIL, reference can be made to ARIB STD-T88 (DSRC
application sub layer).
Figure 1 — CALM MAIL in CALM architecture
2 Conformance
In order for conformance to be claimed with this International Standard, communication shall be established in
full compliance with the procedures and protocols given in ISO 15628, compliant with the appropriate national
or regional standards, and shall be in accordance with ISO 21210, ISO 21217 and ISO 21218.
© ISO 2009 – All rights reserved 1
Management entity
ISO 21210 CME/NME
ISO 24102 IME

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ISO 24103:2009(E)
3 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 15628, Road transport and traffic telematics — Dedicated short range communication (DSRC) — DSRC
application layer
ISO 21210, Intelligent transport systems — Communications access for land mobiles (CALM) — Networking
1)
protocols
ISO 21217, Intelligent transport systems — Communications access for land mobiles (CALM) —
1)
Architecture
ISO 21218, Intelligent transport systems — Communications access for land mobiles (CALM) — Medium
service access points
ISO 24102, Intelligent transport systems — Communications access for land mobiles (CALM) — CALM
2)
Management
4 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
4.1
ISO 15628 DSRC
dedicated short-range communication system for ITS applications with an application layer as specified in
ISO 15628
4.2
base station
fixed DSRC equipment on the roadside, which performs communications with multiple mobile stations
4.3
media adapted interface layer
MAIL
functional structure for using DSRC as a CALM medium
4.4
mobile station
mobile communication facility capable of receiving and transmitting information from/to the base stations
5 Symbols and abbreviated terms
A-PDU application-layer protocol data unit
ARIB association of radio industries and businesses
A-SDU application-layer service data unit
ASN abstract syntax notation

1) To be published.
2) Under preparation.
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ISO 24103:2009(E)
CAL communication adaptation layer
CALM communications access for land mobiles
CI communication interface
CIMAE communication interface management adaptation entity
C-SAP communication SAP, as offered by the CAL to the CALM network layer
DHCP dynamic host configuration protocol
DL data link
DLL data link layer
DSRC dedicated short-range communication
EID element identifier
ELCP extended link control protocol
I-KE initialization kernel element
ind indication (service primitive type)
IP internet protocol
ITS intelligent transport systems
L7 layer 7 (application layer)
LAN local area network
LANCP LAN control protocol
LID link identifier
LPCP local port control protocol
L-PDU lower layer protocol data unit
MAC media access control
MAIL media adapted interface layer
ME management entity
MIB management information base
M-PDU media protocol data unit
MRU maximum receive unit
NCP network control protocol
OBU on-board unit
PDU protocol data unit
PHY-PDU physical layer protocol data unit
req request (service primitive type)
RSU road side unit
SAP service access point
SDU service data unit
TCP transmission control protocol
T-KE transfer kernel element
TTAS telecommunications technology association standard
U-PDU upper layer protocol data unit
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ISO 24103:2009(E)
6 Requirements
6.1 Structure and operation
The MAIL interfaces ISO 15628 DSRC application layer protocol stacks and CALM network protocols to
provide the DSRC with supplemental communications functions (see Figure 2).
The CALM MAIL communication interface (CI) shall be in accordance with
a) ISO 21218, for lower layer service access points,
b) ISO 24102, for interface management
c) ISO 21217, for global architecture, and
d) ISO 21210, for IP networking,
as restricted and/or amended by this International Standard.
This communication interface is a CALM wireless CI which shall
⎯ support CI class CIC-wl5,
⎯ support at least CI access class CIAC-1,
⎯ provide a C-SAP, and
⎯ provide an M-SAP,
all in accordance with ISO 21218.
CALM network layer
SAP
CAL
SAP
NCP/LANCP
ELCP
DSRC with ISO 15628-
compliant L7
CALM MAIL

Figure 2 — Medium adaptation
Figure 3 shows the structure of the core part of MAIL. The MAIL provides IP communications via DSRC to
CALM without requiring awareness of ISO 15628 protocol stacks. The functions that adapt the application
layer of the ISO 15628 DSRC to CALM are defined below.
MAIL consists of the extended link control protocol (ELCP) and the network control protocol (NCP). The ELCP
interfaces with the ISO 15628 protocol stacks, complements them, and provides management functions. The
NCP provides encapsulation functions for upper layer protocols.
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Interface management entity
CIMAE
DSRC ME

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ISO 24103:2009(E)
⎯ The ELCP has the following functions:
1) transmission service control;
2) client/server communication control;
3) communication control management.
⎯ The NCP has the following functions:
1) LAN control;
2) local port control (optional).
The NCP may consist of multiple communication control protocols for interfacing with various types of network
protocols. The LAN control protocol is a communication control protocol which interfaces with the IP network
protocol. The local port control protocol is an optional communication control protocol specified in ISO 29281,
and is used for non-IP network applications. The present International Standard focuses on the LAN control
protocol used to interface with the IPv6 CALM network layer.
CALM non-IP
CALM Network Interface (ISO 21210)
(ISO 29281)
Medium SAP (ISO 21218)
CAL
DLL protocol NCP
LPCP : Local port control
NCP
protocol
LANCP : LAN control protocol
(defined in ISO 29281)
ELCP
ISO 24103
Transmission service control
CALM MAIL
Communication control management
Client /server
communication control
Service processing
MIB
Connection control
(MIB: management information base)
EID
(De) register service
Ready application service ACTION service
I-KE T-KE
ISO 15628
ISO 15628
ISO 15628
layer management
DSRC L7

Figure 3 — Structure of MAIL core part
Figure 4 shows an outline of MAIL operation.
DSRC layer 7 establishes an ISO 15628 DSRC communication link. The ELCP shall be activated by a
notification of a communication link establishment from DSRC L7. After the activation, the ELCP first shall
compare its own MAIL profile with the peer MAIL profile passed through the established communication link
and confirm the available functions in the ELCP. During this stage, the ELCP shall not conduct any settings
related to the NCP.
After the confirmation of MAIL profiles, when an access management function is usable, a peer authentication
may be conducted. In the case of successful authentication, the ELCP may activate the communication
control protocol (e.g. LANCP) in the NCP and start the NCP process phase.
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ISO 24103:2009(E)
The activated NCP shall conduct the initial setting for each communication control protocol in the initial setting
phase. Each network protocol shall be activated only after the completion of the initial setting for the
corresponding communication control protocol in the NCP.
After completion of the above procedure, the communication phase may start to initiate communication using
the network protocol.
Thus, the network protocol, such as IP, is activated.
Out of link connection
Application registration for DSRC L7
Waiting for link connection
Notification of link connection from DSRC L7
Confirmation of MAIL profile
Confirmation of ELCP functions of peer
communication device
Activation of supported functions
Variables set ELCP
in service
Authentication failure
Authentication (optional)
Authentication success
NCP initial setting phase
NCP
in service
Communication phase
End of communication
Link connection termination

Figure 4 — Outline of MAIL operation
6.2 Communication control method
Figure 5 shows an overview of the service interfaces and the protocol stacks of DSRC and MAIL.
The ELCP exchanges the protocol data units (PDU) with the peer ELCP by using the service interface
provided by DRSC L7 and conducts the communication procedures stipulated for the ELCP. The ELCP
provides the service interface of the communication service for the data transmission and the management
service for the management control to the NCP.
The NCP exchanges the PDU with the peer NCP by using the service interface provided by the ELCP and
conducts the communication procedures stipulated for the NCP.
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ISO 24103:2009(E)
Upper layer U-PDU Upper layer
protocol protocol
C-SAP
C-SAP
DLL-PDU
Data link layer Data link layer
protocol protocol
Service primitives Service primitives
+NCP-SDU +NCP-SDU
NCP-PDU ISO 24103
Network control Network control
MAIL specification
protocol protocol
Service primitives Service primitives
+ELCP-SDU +ELCP- SDU
ELCP-PDU
Extended link Extended link
control protocol control protocol
Service primitives Service primitives
+A-SDU +A-SDU
I SO 15628 (D SR C L7)
as normative ref.
A-PDU
DSRC layer 7 DSRC layer 7
L-PDU
DSRC layer 2 DSRC layer 2
M-PDU
M edia (DSRC)
protocol stack
DSRC layer 1 DSRC layer 1
PHY-PDU

Figure 5 — Overview of DSRC and MAIL service interfaces and protocols
7 Extended link control protocol
7.1 General
The ELCP is composed of
a) transmission service control,
b) client/server communication control, and
c) communication control management.
Each entity has peer protocol with its corresponding entity.
NOTE Figure 3 shows the structure of the MAIL core part.
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ISO 24103:2009(E)
7.2 Transmission service control
7.2.1 Communication service interface of extended link control
The communication control of the ELCP provides the following primitives as the communication service to the
NCP:
SendDataUnit.request (linkAddress, networkControlParameter)
SendDataUnit.indication (linkAddress, networkControlParameter)
The “SendDataUnit.request” primitive is sent to the ELCP from the NCP to request that the ELCP-SDU
passed from the NCP be transmitted to the remote station.
The “SendDataUnit.indication” primitive is sent to the NCP from the ELCP, in order to notify the arrival of the
ELCP-SDU.
The logical relationship between communication service primitives provided by the ELCP to the NCP is shown
in Figure 6.
NOTE Service primitive type “request” is abbreviated to “req” and “indication” to “ind”.
Base Mobile
station station
SendDataUnit.req
SendDataUnit.ind
SendDataUnit.req
SendDataUnit.ind

Figure 6 — Logical relationship between communication service primitives
The parameter “linkAddress” indicates the access points of own and remote stations for each NCP
communication control protocol.
The “networkControlParameter” can be either actual ELCP-SDU or pointer for the ELCP-SDU.
7.2.2 Communication services from DSRC layer 7 (L7) interface
The ELCP defines and uses the following services and sub-primitives with the ACTION service provided by
DSRC L7:
⎯ data transfer service;
⎯ data transfer inquiry service.
The ACTION service is defined in ISO 15628.
a) Data transfer service
In the data transfer service, the following sub-primitives are defined by using the “ACTION.request” and
“ACTION.indication” primitives:
SendMessage.request (linkAddress, dataPacket)
SendMessage.indication (linkAddress, dataPacket)
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ISO 24103:2009(E)
The “SendMessage.request” primitive is sent to DSRC L7 of the base station from the ELCP of the base
station to request that the ELCP-PDU generated by the ELCP of the base station be transmitted to the
mobile station.
The “SendMessage.indication” parameter is sent to the ELCP of the mobile station from DSRC L7 of the
mobile station to notify the arrival of the ELCP-PDU.
The parameter “linkAddress” indicates the access points of own and remote stations for the NCP
communication control protocol.
The parameter “dataPacket” can be either actual ELCP-SDU or pointer for the ELCP-SDU and shall be
set in the parameter “actionParameter” of the ACTION primitives.
b) Data transfer inquiry service
In the data transfer inquiry service, the following sub-primitives are defined by using the
“ACTION.request”, “ACTION.indication”, “ACTION.response” and “ACTION.confirm” primitives:
WaitMessage.request (linkAddress, [dataPacket])
WaitMessage.indication (linkAddress, [dataPacket])
WaitMessage.response (linkAddress, [dataPacket])
WaitMessage.confirm (linkAddress, [dataPacket])
The “WaitMessage.request” primitive is sent to DSRC L7 of the base station from the ELCP of the base
station to inquire that the existence of the ELCP-PDU be transmitted to the base station at the mobile
station.
The “WaitMessage.indication” primitive is sent to the ELCP of the mobile station from DSRC L7 of the
mobile station to notify the ELCP of the mobile station of the arrival of the transmission inquiry.
The “WaitMessage.response” primitive is sent to DSRC L7 of the mobile station from the ELCP of the
mobile station to request the return of the response to the transmission inquiry.
The “WaitMessage.confirm” primitive is sent to the ELCP of the base station from DSRC L7 of the base
station to notify the ELCP of the base station of the arrival of the response to the transmission inquiry.
The parameter “linkAddress” indicates the access points of own and remote stations for the NCP
communication control protocol.
The parameter “dataPacket” can be either the actual ELCP-SDU or the pointer for the ELCP-SDU and
shall be set in the parameter “actionParameter” or “responseParameter” of the ACTION primitives.
The logical relationships between the sub-primitives defined in the ACTION primitives are shown in Figure 7.
NOTE Service primitive type “confirm” is abbreviated to “cf” and “response” to “res”.
The parameter “actionType” in the data transfer service and those in the data transfer inquiry service are to be
set to different values.
The values of “actionType” should be registered in the DSRC Layer 7 ActionType Register (see Bibliography).

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ISO 24103:2009(E)
Base Station Mobile Station
SendMessage.req
SendMessage.ind
WaitMessage.req
WaitMessage.ind
WaitMessage.res
WaitMessage.cf

Figure 7 — Logical relationships between sub-primitives defined in ACTION service
7.2.3 Extended link control procedure
7.2.3.1 Base station data transfer service
7.2.3.1.1 Data transmission process
When the primitive requesting the data transmission (“SendDataUnit.request”) is invoked by the NCP, the
ELCP shall obtain the ELCP-SDU from the parameter “networkControlParameter”.
The ELCP-SDU shall be supposed to be invalid in the following two cases:
a) when the size of the ELCP-SDU passed by the parameter “networkControlParameter” exceeds the
maximum receive unit (MRU) of the ELCP, in which case the request primitive shall be discarded and the
state the data size exceeded the buffer upper bound shall be notified by the event notice primitive
(“EventInformation.indication”) to the NCP that requested the transmission;
b) when the transmission queue is full, in which case the ELCP-SDU shall be discarded and the state the
transmission queue is full and transmission failed shall be notified to the NCP that requested the
transmission by the event notice primitive (“EventInformation.indication”).
7.2.3.1.2 Data reception process
When the ELCP-PDU is stored in the receiving queue, the ELCP-SDU shall be sent to the NCP by the data
arrival notice primitive (“SendDataUnit.indication”). Under these circumstances, the ELCP-SDU that is passed
to the NCP shall be extracted from the ELCP-PDU by deletion of the communication control information and
shall be stored in the parameter “networkControlParameter”.
The link address of the ELCP-PDU shall be stored in the parameter “linkAddress”.
The NCP to which the data arrival notice primitive (“SendDataUnit.indication”) is sent shall be identified
according to the access point identifier in the access control information field in the ELCP-SDU. Under these
circumstances, if there is no relevant NCP to be noticed in the station, the ELCP-SDU shall be discarded.
7.2.3.2 Mobile station data transfer service
7.2.3.2.1 Data transmission process
When the primitive requesting data transmission (“SendDataUnit.request”) is invoked by the NCP, the ELCP
shall obtain the ELCP-SDU from the parameter “networkControlParameter”.
When the content of the parameter “linkAddress” is the private link address, the ELCP shall generate the
ELCP-PDU by appending the communication control information to the acquired ELCP-SDU and shall set it to
the transmission queue.
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ISO 24103:2009(E)
However, in the following two cases, the ELCP-SDU shall be supposed to be invalid and shall not be
processed:
a) when the ELCP-SDU passed by the parameter “networkControlParameter” exceeds the MRU of the
ELCP, in which case the request primitive shall be discarded and the state, the data size exceeded the
buffer upper bound, shall be notified by the event notice primitive (“EventInformation.indication”) to the
NCP that requested the transmission;
b) when the transmission queue is full, in which case the ELCP-SDU shall be discarded and the state, the
transmission queue is full and transmission failed, shall be notified by the event notice primitive
(“EventInformation.indication”) to the NCP that requested the transmission.
7.2.3.2.2 Data reception process
When the ELCP-SDU is obtained, it shall be sent to the NCP in the parameter “networkControlParameter” by
the data arrival notice primitive (“SendDataUnit.indication”).
The link address of the ELCP-SDU shall be stored in the parameter “linkAddress”.
The NCP to which the data arrival notice primitive (“SendDataUnit.indication”) is sent shall be identified
according to the access point identifier in the access control information field in the ELCP-SDU. Under these
circumstances, if there is no relevant NCP to be noticed in the station, the ELCP-SDU shall be discarded.
7.3 Client/server communication control
Extended link control protocol performs the procedure of the client/server communication control shown in
Figure 8 in order to enable a transmission from the mobile station. This communication control procedure is
described in 7.3.1 and 7.3.2.
Base station Mobile station
ELCP DSRC DSRC ELCP
The transmission queue is empty. WaitMessage.req WaitMessage.ind
The transmission queue
Send transmission inquiry.
.
is empty
WaitMessage.cf WaitMessage.res
Response with the data null.
Request for the
When the data is null, send
(1)
packet transmission.
transmission inquiry again.
Registration of the queue.
WaitMessage.req WaitMessage.ind
Request for the packet transmission.
The transmission
(2)
Registration in the queue.
.
queue is
...