ISO 21215:2010

Intelligent transport systems - Communications access for land mobiles (CALM) - M5

ISO 21215:2010 provides specifications of the access layer (OSI layers 1 and 2 and the related management functionality) of a communication interface (CI) named "CALM M5", operating in the 5 GHz microwave frequency range.

Systèmes intelligents de transport — Accès aux communications des services mobiles terrestres (CALM) — M5

General Information

• Status: Withdrawn
• Publication Date: 04-Nov-2010
• Withdrawal Date: 04-Nov-2010
• 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: 9599 - Withdrawal of International Standard
• Start Date: 22-May-2018
• Completion Date: 13-Dec-2025

Relations

• Revised: ISO 21215:2018 - Intelligent transport systems - Localized communications - ITS-M5
• Effective Date: 05-Nov-2015

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 21215
First edition
2010-11-15
Intelligent transport systems —
Communications access for land mobiles
(CALM) — M5
Systèmes intelligents de transport — Accès aux communications des
services mobiles terrestres (CALM) — M5

Reference number
©
ISO 2010
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©  ISO 2010
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ii © ISO 2010 – All rights reserved

Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .2
4 Symbols and abbreviated terms .2
5 Requirements.3
6 Architecture .4
7 Communication interface protocol stack.5
7.1 Physical layer.5
7.2 Medium access control layer .7
7.2.1 General .7
7.2.2 Elements.7
7.2.3 MAC procedures.11
7.3 Logical link control sub-layer .12
7.4 Communication adaptation layer.12
7.4.1 General .12
7.4.2 Elements.12
7.4.3 CAL procedures.15
8 Communication interface management.17
8.1 Communication module management entity.17
8.2 Communication interface management adaptation entity.17
8.2.1 Mapping of 802.11 parameters.17
8.2.2 Mapping of 802.11 commands .17
8.2.3 Management frames.18
8.2.4 Cross-CI prioritization procedure .18
8.2.5 CI registration .19
8.2.6 VCI deletion.19
8.2.7 Regulatory information management.20
8.2.8 MI-parameters .20
9 Conformance .22
10 Test methods .22
11 Marking, labelling and packaging.22
Annex A (normative) Parameters .23
Annex B (normative) MI-COMMAND .31
Annex C (normative) MI-REQUEST .32
Annex D (normative) Management frame MAC commands .33
Annex E (normative) ASN.1 definitions .34
Annex F (informative) Operation in Europe.37
Bibliography.39

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 21215 was prepared by Technical Committee ISO/TC 204, Intelligent transport systems.
iv © ISO 2010 – All rights reserved

Introduction
This International Standard is part of a family of International Standards for communications access for land
mobiles (CALM). An introduction to the whole set of International Standards is provided in ISO 21217.
This International Standard determines the CALM native medium using radio frequencies in the 5 GHz
microwave range. This medium is named CALM M5.
CALM M5 was developed with knowledge of the work done at IEEE on WAVE; see IEEE 1609.4 and [14].
CALM M5 is based on the work done in IEEE P802.11p [16], which cannot be referenced at the time of writing
this International Standard, as this will become part of IEEE 802.11.
A CALM M5 communication interface can be integrated with a CEN dedicated short-range communication
(DSRC) on-board unit (OBU) that is compliant with [11], [12] and [13]. This is to efficiently protect payment
transactions based on CEN DSRC systems that are globally in use.

INTERNATIONAL STANDARD ISO 21215:2010(E)

Intelligent transport systems — Communications access for
land mobiles (CALM) — M5
1 Scope
This International Standard provides specifications of the access layer (OSI layers 1 and 2 and the related
management functionality) of a communication interface (CI) named "CALM M5", operating in the 5 GHz
microwave frequency range.
CALM M5 CIs include communication modules (CMs) that are based on the wireless LAN technology
standardized at IEEE. This International Standard specifies the additions to and deviations from IEEE 802.11,
including the amendment [16] developed by IEEE Task Group p (TGp) required to make CALM M5 CIs
compatible with the ITS station reference architecture based on the CALM concept specified in ISO 21217.
Frequency allocations in regions other than North America are supported.
2 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/IEC TR 8802-1, Information technology — Telecommunications and information exchange between
systems — Local and metropolitan area networks — Specific requirements — Part 1: Overview of Local Area
Network Standards
ISO/IEC 8802-2, Information technology — Telecommunications and information exchange between
systems — Local and metropolitan area networks — Specific requirements — Part 2: Logical link control
IEEE 802.11, Information technology — Telecommunications and information exchange between systems —
Local and metropolitan area networks — Specific requirements — Part 11: Wireless LAN Medium Access
Control (MAC) and Physical Layer (PHY) Specifications
IEEE 1609.4, IEEE Trial-Use Standard for Wireless Access in Vehicular Environments (WAVE) — Multi-
channel Operation
ISO/IEC 8825-2, Information technology — ASN.1 encoding rules: Specification of Packed Encoding Rules
(PER)
ISO 21210, Intelligent transport systems — Communications access for land mobiles (CALM) — IPv6
Networking
ISO 21217, Intelligent transport systems — Communications access for land mobiles (CALM) — 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) — Management
ISO 29281, Intelligent transport systems — Communications access for land mobiles (CALM) — Non-IP
networking
ETSI EN 302 571:2007, Intelligent Transport Systems (ITS); Radiocommunications equipment operating in
the 5 855 MHz to 5 925 MHz frequency band; Harmonized EN covering the essential requirements of article
3.2 of the R&TTE Directive
ETSI EN 301 893:2007, Broadband Radio Access Networks (BRAN); 5 GHz high performance RLAN;
Harmonized EN covering the essential requirements of article 3.2 of the R&TTE Directive
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 21217, ISO 21210, ISO 24102,
ISO 21218, ISO/IEC 8802-2, IEEE 802.11, ETSI EN 301 893:2007, ETSI EN 302 571:2007 and the following
apply.
NOTE Terminology in the set of CALM standards was modified during the process of harmonizing International
Standards. This might lead to an editorial difference in terms used in this International Standard and in other International
Standards from the set of CALM standards. These editorial differences will be resolved during the ongoing process of
harmonizing the whole set of CALM standards.
3.1
CALM M5
CALM communication interface that is compliant with one or more modes of operation in the 4 GHz to 5 GHz
band as specified in this International Standard (ISO 21215:2010)
3.2
control channel
logical channel associated with a physical communication channel to manage the access of applications to the
communication medium which can include assignment of a service channel or an auxiliary channel to an
application
3.3
service channel
logical channel associated with a physical communication channel
3.4
auxiliary channel
logical channel associated with a physical communication channel
4 Symbols and abbreviated terms
For the purposes of this document, the abbreviated terms given in ISO 21217, ISO 29281, ISO 21210,
ISO 24102, ISO 21218, ISO/IEC 8802-2, IEEE 802.11, ETSI EN 301 893:2007, ETSI EN 302 571:2007 and
the following apply.
ACH Auxiliary Channel
CAL Communication Adaptation Layer
CCH Control Channel
CI Communication Interface
CM Communication Module
2 © ISO 2010 – All rights reserved

DSRC Dedicated short-range communication
ITS-S Intelligent Transport System Station
ITS-SI Intelligent Transport System Station Information
MAC Medium Access Control Sub-layer
MI-parameter Parameter of a CI or virtual CI (VCI) specified in ISO 21218
M5-parameter Parameter of a CALM M5 CI / VCI specified in this International Standard (ISO 21215:2010)
OBU On-board unit
PHY Physical layer for microwave communications
QoS Quality of Service
SCH Service Channel
VCI Virtual Communication Interfaces
, Commas within numbers are used as decimal points
e.i.r.p. Equivalent isotropic radiated power
c speed of light in m/s
d estimated free space communication distance
f centre frequency in Hz
G gain of receiver antenna
L implementation specific losses
impl
L path loss
path
P receiver sensitivity
sens
P transmit power e.i.r.p
tx
5 Requirements
Clauses 6, 7 and 8 provide the principal requirements of this International Standard:
⎯ Clause 6 specifies the global architecture based on the OSI model, together with general requirements by
reference to other International Standards;
⎯ Clause 7 specifies the CALM M5 communication interface protocol stack;
⎯ Clause 8 specifies the CALM M5 communication interface management.
Annexes provide further normative and informative details.
6 Architecture
Figure 1 shows the architecture diagram of a CALM M5 communication interface (CI) embedded in the
general CALM architecture.
Figure 1 — CALM M5 CI architecture
The M5 communication module (CM) is indicated with a bold dotted line. The CM along with the
communication adaptation layer (CAL) and CI management adaptation entity (CIMAE) constitute a CALM CI
as specified in ISO 21218.
The communication protocol layers of the CM are
a) physical layer for microwave communications (PHY), and
b) medium access control sub-layer (MAC).
A CALM M5 CI shall comply with the following CALM International Standards:
⎯ ISO 21218 on access layer service access points;
⎯ ISO 24102 on ITS station management;
⎯ ISO 21217 on global ITS architecture;
⎯ ISO 29281 on non-IP networking; and
⎯ ISO 21210 on IPv6 networking;
with restrictions and amendments as specified in this International Standard.
A CALM M5 CM shall be compliant with IEEE 802.11 with restrictions and amendments as specified in this
International Standard.
A CALM M5 CI and virtual CI (VCI) shall support MI-parameters specified in ISO 21218 with amendments and
restrictions as specified in this International Standard.
4 © ISO 2010 – All rights reserved

A CALM M5 CI as specified in this International Standard is a CALM wireless CI that shall support CI class
CIC-wl1 for general simultaneous bi-directional communications with multiple peer stations, coded in
MI-parameter 15 "CIclass" specified in ISO 21218.
NOTE 1 This includes the capability of CI class CIC-wl3 and CIC-wl4.
A CALM M5 CI shall support at least CI access class CIAC-1 coded in MI-parameter 24 "CIaccessClass"
specified in ISO 21218.
A CALM M5 CI shall provide an IN-SAP and an MI-SAP as specified in ISO 21218 with restrictions as
specified in this International Standard.
A CALM M5 CI shall support Cross-CI prioritization as specified in ISO 21218 with details as specified in this
International Standard.
NOTE 2 Multiple CALM M5 CIs per ITS station are possible, regardless of whether the CIs belong to the same
ITS-SCU or to different ITS-SCUs; see ISO 24102 for the specification of an ITS-SCU.
A CALM M5 CI shall support all modes of usage of the CtrlCI bits in the CI-ID as specified in ISO 29281 with
details as specified in this International Standard.
A CALM M5 CI shall support packets carrying management data being transferred via the MI-SAP as
specified in ISO 21218.
A CALM M5 CI shall support one or more of the logical channels "control channel" (CCH), "service channel"
(SCH) and "auxiliary channel" (ACH) as specified in ISO 21218.
A CALM M5 CI shall provide quality of service (QoS) functionality based on user priorities as specified in
ISO 21218, and based on access categories as specified in IEEE 1609.4.
7 Communication interface protocol stack
7.1 Physical layer
The physical layer of a CALM M5 CI shall be compliant with IEEE 802.11, orthogonal frequency division
multiplexing (OFDM) PHY specification for the 5 GHz band, with restrictions and amendments as specified in
this International Standard.
Figure 2 shows the PHY frame as transmitted in the microwave medium. It consists of a "PHY Header", a
"MAC Frame" and an optional "PHY Trailer".
PHY MAC PHY
Header Frame Trailer
Figure 2 — PHY frame
Table 1 shows how CALM M5 channels are identified by means of "CALM channel number", centre frequency,
bandwidth (channel spacing) and channel set identifier. "CALM channel number" is a reference number to the
following set of parameters:
⎯ IEEE channel starting frequency;
⎯ IEEE channel number;
⎯ channel bandwidth (channel spacing); and
⎯ channel set identifier (region code, set identifier).
See the ASN.1 element M5channel specified in Annex E. A "CALM channel number" shall be unique inside an
ITS station.
Table 1 — Centre frequencies — Informative
CALM channel number As assigned to CCH, SCH, ACH. The value zero shall not be
assigned to the CALM channel number as it has a special
meaning; see MI-parameters 0, 1, and 2 specified in ISO 21218.
IEEE channel starting frequency Used to calculate the centre frequency as specified in
IEEE 802.11.
As specified in IEEE 802.11.
IEEE channel number
Bandwidth in MHz Equals the IEEE channel spacing.
Channel set identifier Points to a regulation.

NOTE 1 Channel set identifier details are outside the scope of this International Standard.
In Europe, CALM M5 shall comply with the harmonized standards ETSI EN 301 893:2007 and
ETSI EN 302 571:2007, respectively, for the frequency bands covered by these ENs. Frequency allocation
and some modes of operation in Europe are presented in Annex F.
In case there is only a single common RX-VCI for all TX-VCIs of the same CI, all virtual VCIs of a CI shall use
the same centre frequency and bandwidth.
All data rates for a given channel bandwidth as indicated in Table 2 may be supported; the lowest data rate for
each supported channel bandwidth shall be mandatory.
Table 2 — Data rates
IEEE Modulation 0 1 2 3 4 5 6 7
coding scheme (MCS)
Data rate in Mbit/s 12 18 24 36 48 72 96 108
40 MHz channels
Data rate in Mbit/s 9 13,5 18 27 36 54 72 81
30 MHz channels
Data rate in Mbit/s 6 9 12 18 24 36 48 54
20 MHz channels
Data rate in Mbit/s 3 4,5 6 9 12 18 24 27
10 MHz channels
IEEE RATE coding '1101' '1111' '0101' '0111' '1001' '1011' '0001' '0011'
R1 … R4
BPSK BPSK QPSK QPSK 16- 16- 64- 64-
Modulation scheme
QAM QAM QAM QAM
Coding rate R 1/2 3/4 1/2 3/4 1/2 3/4 2/3 3/4

The transmitter power (e.i.r.p.) shall be adjustable in steps of 0,25 dB.
NOTE 2 The step size indicates resolution; accuracy can be worse than resolution.
6 © ISO 2010 – All rights reserved

7.2 Medium access control layer
7.2.1 General
The medium access control layer of a CALM M5 CI shall be compliant with IEEE 802.11, with restrictions and
amendments as specified in this International Standard.
7.2.2 Elements
7.2.2.1 Frame format
Figure 3 shows details of the CALM M5 MAC frame presented in Figure 2.
MAC Header LLC PDU FCS
Figure 3 — CALM M5 MAC frame
Details of the "MAC Header" are specified below. The FCS shall be constructed as specified in IEEE 802.11.
7.2.2.2 MAC header
The general format of the "MAC Header" as applicable for data frames of type "DATA" and "QoS DATA", and
for management frames of type "BEACON" and "ACTION", see Table 3, is specified in IEEE 802.11 and
presented in the informative Figure 4.
NOTE 1 The MAC header of the data frame "DATA" does not contain the element "QoS Control".
Frame Duration / Sequence QoS
Address 1 Address 2 Address 3 Address 4
Control ID Control Control
2 octets 2 octets 6 octets 6 octets 6 octets 6 octets 2 octets 2 octets
Figure 4 — MAC header for data frames
"Address 1" and "Address 2" in Figure 4 shall be the MAC addresses of the destination VCI and source VCI,
respectively.
The general format of the "Frame Control" field is presented in the informative Figure 5.
Protocol To From More Pwr More
Type Subtype Retry WEP Order
Version DS DS Frag Mgt Data
2 bits 2 bits 4 bits 1 bit 1 bit 1 bit 1 bit 1 bit 1 bit 1 bit 1 bit
Figure 5 — MAC frame control field
The "Protocol Version" field shall be set to the value zero.
"Type" and "Subtype" combinations specified in IEEE 802.11 are as presented in Table 3.
Table 3 — 802.11 frame types
Type Frame type Subtype Name
'00' Management frame '1101' ACTION
'1000' BEACON
'10' Data frame '0000' DATA
QoS DATA
'1000'
'01' Control frame '1011' RTS
'1100' CTS
'1101' ACK
The "Duration / ID" field shall indicate the time in microseconds needed for transmission of the frame.
NOTE 2 Fragmentation at the MAC layer can be avoided by proper restriction of packet size above the MAC layer.
The 12 bit sub-field "Sequence Number" shall be incremented in every new frame. It shall wrap from the value
4095 to zero.
The "QoS Control" field, if present, shall be set as specified in Table 4.
Table 4 — QoS control field elements
Bit numbers Element Values Explanation
3 – 0 TID 0 – 7 Priority of packet, see Tables 9
and 10
8 – 15 Reserved for future use
4 EOSP '0' Defines meaning of bits 8 – 15
'1' '1' shall be used for operation
outside the concept of a BSS
6 – 5 Ack Policy '00' Acknowledgement
'10' No acknowledgement
7 Reserved '0' Reserved for future use
15 – 8 EOSP = '0': TXOP Duration Requested — —
EOSP = '1': Queue Size
7.2.2.3 MAC addresses
7.2.2.3.1 Assignment of MAC addresses
There shall be a MAC address identifying uniquely a CALM M5 CI.
The VCIs of a CALM M5 CI shall be identified by a MAC address, which
a) either is the same MAC address as that of the CI,
b) or is a locally administered MAC address.
A locally administered MAC address may either be unique in the CI or be shared by all or some VCIs.
8 © ISO 2010 – All rights reserved

7.2.2.3.2 Format
The MAC address of a CALM M5 CI / VCI shall be constructed according to the convention as specified in
ISO/IEC TR 8802-1. It is a six octet number with bits b0 through b47. Figure 6 illustrates the format of a MAC
address.
Figure 6 — MAC address format
In a source MAC address, the I/G bit shall be set to zero always.
The broadcast MAC address shall be given by setting all bits to one.
7.2.2.3.3 Multicast address
Multicast MAC addresses shall be constructed as specified in ISO/IEC TR 8802-1.
The multicast group number contained in the multicast MAC address shall be mapped uniquely to the
"SerialNumber" in the CI-ID of "destination_address" specified in ISO 21218. The mapping shall be known
both in the CI / MC-VCI and in the ITS station management.
The mapping shall be reported for the whole CI in M5-parameter 254.5.6 "MulticastMACs" as specified in
ISO 21218.
7.2.2.3.4 Unicast address
For individual MAC addresses a unique mapping of peer MAC address to "SerialNumber" shall be performed
as specified in ISO 21218.
7.2.2.3.5 Locally administered address
Locally administered MAC addresses are allowed in addition to global individual MAC addresses. In order to
achieve uniqueness within a station
⎯ octet 5 shall be set equal to the ITS-SCU-ID, and
⎯ bits 8 to 39 and 42 to 47 shall be set randomly considering the locally administered MAC addresses of
known peer stations, if applicable, in order to minimize the risk of duplicate MAC addresses in the system,
and
⎯ Bit 40 "I/G" shall be set to '0', and
⎯ Bit 41 "U/L" shall be set to '1'.
NOTE 1 In case of locally administered MAC addresses, uniqueness of the MAC address can be guaranteed only
within a single ITS station.
A CALM M5 CI shall continuously monitor whether a peer station is using the same MAC address. In case of a
detected conflict, the CI shall change the MAC address of the related VCI considering the MAC addresses of
all known peer stations. The new MAC address shall be notified to the ITS station management as specified in
ISO 21218 and in ISO 24102.
Upon notification of change of own MAC address, the ITS station management shall request to send ITS-SI
data in a broadcast frame specified in ISO 24102 and in ISO 29281.
NOTE 2 Change of MAC address will break active upper layer sessions. In case unique station identifiers are used,
upper layer sessions may be maintained.
7.2.2.4 Channel access
The right to access a physical channel depends on the logical channel CCH, SCH and ACH assigned to a
physical channel, and on the user priority assigned to the user application.
The access is defined by the QoS scheme specified in ISO 21218 based on user priorities, and by the
mapping of user priorities on logical channels as specified in Table 9.
7.2.2.5 Enhanced distributed channel access
The "Distributed Coordination Function" (DCF) applying "Carrier Sense Multiple Access with Collision
Avoidance" (CSMA/CA) shall be mandatory for operation outside the context of a BSS.
For operation outside the context of a BSS, only contention-based channel access shall be applied, thus the
"Enhanced Distributed Channel Access" (EDCA) method defined in IEEE 802.11 shall be mandatory and the
"HCF Controlled Channel Access" (HCCA) method defined in IEEE 802.11 shall be prohibited. The default set
of EDCA parameters shall be as specified in Table 5. The ITS station manager may update these parameters
using information from a trusted source.
10 © ISO 2010 – All rights reserved

Table 5 — EDCA parameters
Access Contention window Contention window Arbitration interframe Transmit
category CWmin CWmax space number AIFSN opportunity
limit TXOP
CCH SCH ACH CCH SCH ACH CCH SCH ACH
AC_BK 15 15 15 1023 1023 1023 9 8 7 0
AC_BE 7 11 15 15 511 1023 6 5 4
AC_VI 3 5 7 7 11 15 3 2 2
AC_VO 3 3 3 7 7 7 2 2 2
NOTE Units of parameters presented in this table are as specified in IEEE 802.11.

7.2.2.6 Data frames
7.2.2.6.1 User priority and access category
The IN-SAP service primitives DL-UNITDATA contain the parameter "priority", which is the CALM user priority.
The supported relation between user priority and TID / access category shall be as specified in Tables 9
and 10.
7.2.2.6.2 DATA
A VCI shall use the data frame type "DATA" specified in IEEE 802.11 if M5-parameter 254.5.1
"DataFrameType" is set to 0x08.
7.2.2.6.3 QoS DATA
A VCI shall use the data frame type "QoS DATA" specified in IEEE 802.11 if M5-parameter 254.5.1
"DataFrameType" is set to 0x88.
7.2.2.7 Management frames
Usage of management frames specified in IEEE 802.11 via MI-SAP shall be restricted to data packets of ITS
station management applications, i.e. ITS-S applications' transmission requests shall never be performed by
management frames.
7.2.3 MAC procedures
7.2.3.1 Fragmentation
The size of the physical layer protocol data unit (PPDU) in the physical layer of CALM M5 is limited to
2 304 bytes. IEEE 802.11 provides for fragmentation of large packets into subsequent frames. Fragmentation
of packets at the MAC layer may be avoided by proper restriction of packet size above the MAC layer.
7.2.3.2 Channel access limitation
A CALM M5 CI shall access the wireless channel for no more than a specified percentage of time. The
percentage is given by an observation time span and a maximum access time within this observation time
span for each logical channel type as specified by the M5-parameter 254.5.4 "AccessLimit". Actual values
may depend on regulation. If such an access limitation is not needed, then the observation time span "period"
in "LimitChannel" and the maximum access time "limit" shall be set to zero.
NOTE This approach allows specific applications, e.g. road safety-related applications, to always access a specific
logical channel without access limitations.
7.3 Logical link control sub-layer
The "Communication Adaptation Layer" (CAL) presented in Figure 1 contains the whole functionality of the
LLC sub-layer of CALM M5.
7.4 Communication adaptation layer
7.4.1 General
CALM M5 shall support the minimum LLC-functionality as specified in ISO 21218 with amendments as
specified in this International Standard.
"Type 2" operation as specified in ISO/IEC 8802-2 shall be prohibited.
"Type 3" operation as specified in ISO/IEC 8802-2 may be supported optionally, and shall be restricted to
auxiliary channels (ACH).
Pending management packets and data packets shall share common priority queues as specified in
ISO 21218.
7.4.2 Elements
7.4.2.1 LPDU format
The format of the CALM M5 LPDU shall be as specified in Figure 7.
LLC
DSAP SSAP NPDU
Header
1 octet 1 octet variable variable
Figure 7 — CALM M5 LPDU
For example, in case the fields DSAP and SSAP contain the value 0xAA, the SNAP protocol is selected and a
SNAP header is inserted between LLC header and NPDU. The SNAP header has a size of five octets. The
LLC header, in this case, has a limited size of one octet. The CALM M5 LPDU with SNAP is presented in
Figure 8.
DSAP SSAP LLC SNAP
NPDU
= 0xAA = 0xAA Header Header
1 octet 1 octet 1 octet 5 octets variable
Figure 8 — CALM M5 LPDU with SNAP
An LLC header with size of one octet shall be constructed as specified in Table 6. Further details of the LLC
header, including the address elements "DSAP" and "SSAP", are specified in ISO 21218. Details of the
payload "NPDU" are specified in the following subclauses.
12 © ISO 2010 – All rights reserved

Table 6 — CALM M5 LLC header
Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Command
(LSB)
1 1 M0 M1 P/F M2 M3 M4
1 1 0 0 0 0 0 0 LLC header for UI command as specified
in ISO/IEC TR 8802-1.
1 1 CIP0 CIP1 0 CIP2 0 0 UI command, but with "CI Parameter"
(CIP) field in NPDU.
1 1 0 0 P 1 1 1 LLC header for TEST command as
specified in ISO/IEC TR 8802-1.
1 1 0 0 P 1 0 1 LLC header for XID command as
specified in ISO/IEC TR 8802-1
(prohibited for FAST communication).

The LLC header presented in Table 6 is a modification of the header defined in ISO/IEC TR 8802-1 for "Type
1" operation. The original coding of UI command, TEST command and XID command is maintained.
Modifier bits M2, M1 and M0 shall be used to indicate the type of CIP field included in the frame as specified
in Tables 6 and 7.
The TX parameters that may be reported in a DL-UNITDATA.request and DL-UNITDATA.indication service
primitive are
⎯ MI-parameter 4 "TXpower" as specified in ISO 21218, and
⎯ MI-parameter 5 "DataRate" as specified in ISO 21218.
The coding of these options shall be as specified in Table 7.
Table 7 — CI transmitter parameters
CIP2 CIP1 CIP0 Type Parameters contained Total size in octets
0 0 0 0 nothing contained 0
0 0 1 1 TX power 1
0 1 0 2 TX power, DataRate 5
0 1 1 3 reserved for future use
1 0 0 4 reserved for future use
1 0 1 5 reserved for future use
1 1 0 6 reserved for future use
1 1 1 7 reserved for future use

The RX parameters that may be reported in a DL-UNITDATA.indication service primitive can be defined by
the ITS station management. Up to seven different settings are possible.
The coding of these options shall be as specified in Table 8. The selection of a type shall be according to
M5-parameter 254.5.3 "CIPrxType". Details depend on implementation.
Table 8 — CI receiver parameters
CIP2 CIP1 CIP0 Type Parameters contained Total size in octets
0 0 0 0 nothing contained 0
0 0 1 1 Setting number 1 depends on actual setting
0 1 0 2 Setting number 2 depends on actual setting
0 1 1 3 Setting number 3 depends on actual setting
1 0 0 4 Setting number 4 depends on actual setting
1 0 1 5 Setting number 5 depends on actual setting
1 1 0 6 Setting number 6 depends on actual setting
1 1 1 7 Setting number 7 depends on actual setting

The default receiver CIP type shall be CIPrxType = 0.
7.4.2.2 NPDU
In this context, the "Network Protocol Data Unit" (NPDU) is equal to the "data" parameter of the
DL-UNITDATA service as specified in ISO 21218. The structure of the NPDU as being present in the frame
shall be as specified in Figure 9.
Network and Transport
CIP Header APDU
Header
Figure 9 — CALM NPDU
The NPDU consists of
⎯ an optional "CIP Header" element, transmitted first in the frame,
⎯ a "Network and Transport Header" element, and
⎯ an "APDU" element.
The "CIP Header" may include
⎯ TX parameters as received in the frame and as used at the peer station for transmission of the frame,
⎯ RX parameters of the receiving VCI, and
⎯ TX parameters to be used in the transmitting VCI prior to transmission of the frame.
14 © ISO 2010 – All rights reserved

The presence of the "CIP Header" with TX parameters in a frame shall be indicated in the CALM M5 LLC
header as specified in Table 6.
The presence of the "CIP Header" with TX parameters in a DL-UNITDATA.request service primitive shall be
indicated by means of CtrlCI bit settings as specified in ISO 29281.
The presence of the "CIP Header" with TX parameters in a DL-UNITDATA.indication service primitive shall be
indicated by means of CtrlCI bit settings as specified in ISO 29281.
The presence of the "CIP Header" with RX parameters in a DL-UNITDATA.indication service primitive shall be
indicated by means of CtrlCI bit settings as specified in ISO 29281.
Details on the "Network Header", "Transport Header", "Data Header" and "Application Data" are outside the
scope of this International Standard.
7.4.3 CAL procedures
7.4.3.1 Mapping of CALM user priority on TID values
CALM user priorities as used in parameter "priority" of the DL-UNITDATA.request service primitive specified in
ISO 21218 shall be mapped to IEEE access categories (AC) and IEEE TID values as specified in Table 9.
See also Table 9-1 in IEEE 802.11.
Table 9 — CALM user priorities and IEEE access categories for TX
Access category (AC) CALM user
priority
AC_VO 224 - 255
192 - 223
AC_VI 160 - 191
128 - 159
AC_BK 96 - 127
64 - 95
AC_BE 32 - 63
0 - 31
Table 10 — CALM user priorities for RX
TID CALM user priority
unknown 0
1 31
2 63
0 95
3 127
4 159
5 191
6 223
7 255
All 802.11 QoS data frames report a TID value. Non-QoS data frames do not report a TID value, which is
interpreted as "unknown".
7.4.3.2 CIP management
7.4.3.2.1 Transmission of a packet
Upon reception of a DL-UNITDATA.request service primitive, CAL shall check the CtrlCI bits in the
destination_address. The actions as presented in Table 11 shall be mandatory prior to transmission of the
frame.
Table 11 — CIP management for TX
C4 C3 C2 C1 CIP management action
'0' '0' '0' '0' No further CIP management action needed.
Set bits 2, 3 and 5 in the CALM M5 LLC header, see Table 6, to zero.
CIP2 CIP1 CIP0 '0' Evaluate and apply TX CIP parameters according to the meaning of the
values of CIP0, CIP1 and CIP2 specified in Table 7 and remove them
from NPDU prior to transmission of frame.
Set bits 2, 3 and 5 in the CALM M5 LLC header, see Table 6, to zero.
CIP2 CIP1 CIP0 '1' Evaluate and apply TX CIP parameters according to the meaning of the
values of CIP0, CIP1 and CIP2 specified in Table 7 and keep them in the
NPDU for transmission in the frame.
Copy CIP0, CIP1 and CIP2 into the CALM M5 LLC header, see Table 6.

16 © ISO 2010 – All rights reserved

7.4.3.2.2 Reception of a frame
Upon reception of a frame, and prior to sending the packet to the CALM networking via IN-SAP, check the
CALM M5 LLC header specified in Table 6. The actions as presented in Table 12 and below this table are
mandatory.
Table 12 — CIP management for RX
Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7
CIP management action
(LSB)
1 1 M0 M1 P/F M2 M3 M4
1 1 CIP0 CIP1 0 CIP2 1 1 Copy CIP0, CIP1 and CIP2 into CtrlCI bits
C2, C3 and C4 of the source_address of
the DL-UNITDATA.indication service
primitive as specified in ISO 29281.

Check M5-parameter 254.5.3 "CIPrxType" and insert CIP parameters as specified in Table 8 in the NPDU as
specified in ISO 29281. Copy bits CIP0, CIP1 and CIP2 as specified in Table 8 for the given value of
CIPrxType into the CtrlCI bits C2, C3 and C4 of the destination_address of the DL-UNITDATA.indication
service primitive as specified in ISO 29281.
Then process the packet further for transmission via IN-SAP to the CALM networking layer.
8 Communication interface management
8.1 Communication module management entity
The CM management shall be compliant with IEEE 802.11, with restrictions and amendments as specified in
this International Standard.
8.2 Communication interface management adaptation entity
8.2.1 Mapping of 802.11 parameters
All IEEE 802.11 parameters that have an equivalent MI-parameter defined in ISO 21218 shall be mapped on
MI-parameters. All IEEE 802.11 parameters which are relevant for CALM M5 and do not have an equivalent
MI-parameter defined in ISO 21218 can be made visible to the ITS station management by means of medium-
specific MI-parameters as specified in this International Standard. MI-parameters which are relevant for CALM
M5 but cannot be mapped on an IEEE 802.11 parameters shall be implemented in the CIMAE as specified in
ISO 21218.
8.2.2 Mapping of 802.11 commands
All IEEE 802.11 management commands that have an equivalent MI-COMMAND / MI-REQUEST defined in
ISO 21218 shall be mapped on these MI-COMMAND / MI-REQUEST. All IEEE 802.11 parameters which are
relevant for an implementation of CALM M5 and do not have an equivalent MI-COMMAND / MI-REQUEST
defined in ISO 21218 can be made accessible in an implementation-specific way. MI-COMMANDs / MI-
REQUESTs which are relevant for CALM M5 but cannot be mapped on an IEEE 802.11 management
commands shall be implemented in the CIMAE as specified in ISO 21218.
Annex B provides information on MI-COMMANDs. Annex C provides details on MI-REQUESTs.
8.2.3 Management frames
Transmission of management frames may be requested by the ITS station management with the MI-
COMMAND 255 "UnitDataCmd" as specified in ISO 21218. The data packet shall be transmitted in a
management frame of type "Action" or "BEACON", see Table 3.
Parameters "sourceAddr" and "destAddr" of "UnitDataCmd" shall be treated the same way as the CI-IDs
contained in parameters "sourceAddr" and "destAddr" of the service primitive "DL-UNITDATA.request"
specified in ISO 21218.
Parameter "data" of "UnitDataCmd" shall be copied into the CALM information element.
Parameter "priority" of "UnitDataCmd" shall be treated the same way as parameter "priority" of the service
primitive "DL-UNITDATA.request".
Parameter "parameter" shall be as specified in Table 13.
Table 13 — Management frame parameter "parameter"
Elements of "parameter" Range of value Description
MFcmds SEQUENCE OF MFcmd
MFcmd SEQUENCE Sequence of defined MAC commands
MFcmd.ID 0 - 255 Identifier of specific MAC command MFcmd,
unique for CALM M5
MFcmd.value Depends on MFparam.ID Value of specific MAC command MFcmd

Annex D shows MAC management frame commands MFcmd.
Management frames received from a peer station shall be forwarded to the ITS station management with the
MI-REQUEST 255 "UnitDataCmd" as specified in ISO 21218 and in ISO 29281.
Parameters "sourceAddr" and "destAddr" of "UnitDataCmd" shall be set the same way as the CI-IDs
contained in parameters "sourceAddr" and "destAddr" of the service primitive "DL-UNITDATA.indication"
specified in ISO 21218.
Parameter "data" of "UnitDataCmd" shall be set equal to the contents of the CALM information element.
Parameter "priority" of "UnitDataCmd" shall be treated the same way as parameter "priority" of the service
primitive "DL-UNITDATA.indication" specified in ISO 21218.
Parameter "parameter" of "UnitDataCmd" shall be as specified in Table 13.
8.2.4 Cross-CI prioritization procedure
The basic "Cross-CI prioritization procedure" is specified in ISO 21218 and ISO 24102. For CALM M5 the
option
...