ISO 21215:2010

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 21215:2010(E)
©
ISO 2010

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ISO 21215:2010(E)
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ISO 21215:2010(E)
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

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ISO 21215:2010(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 21215 was prepared by Technical Committee ISO/TC 204, Intelligent transport systems.
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ISO 21215:2010(E)
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.

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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
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ISO 21215:2010(E)
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
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ISO 21215:2010(E)
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.
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ISO 21215:2010(E)
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.
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ISO 21215:2010(E)
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.
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ISO 21215:2010(E)
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.
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ISO 21215:2010(E)
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.
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ISO 21215:2010(E)
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.
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ISO 21215:2010(E)
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.
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ISO 21215:2010(E)
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.
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ISO 21215:2010(E)
Table 5 — EDCA parameters
Access Contention window Contention windo
...