Introduction
NR connected to 5GC provides support for Public Warning
Systems (PWS) by means of system information broadcasting.
NR is responsible for scheduling and broadcasting of
the warning messages.
NR is also responsible for paging the UE to provide
indication that the warning message is being broadcasted.
Earthquake
and Tsunami Warning System (ETWS) is a public warning
system developed to meet the regulatory requirements for warning notifications
related to earthquake and/or tsunami events.
- ETWS warning notifications
can either be a primary notification (short notification) or secondary
notification (providing detailed information).
-
ETWS Primary
Notification shall:
· convey data which is small
enough to be sent quickly on the network.
· convey small amount of data
to indicate the imminent occurrence of Earthquake and Tsunami, etc.
· be delivered within 4
seconds to the UE in the Notification Area even under congestion situation.
-
ETWS Secondary
Notification may:
· convey a large amount of
data in order to deliver text, audio to instruct what to do/where to get help,
graphical data such as a map indicating the route from present position to
evacuation site, timetable of food distribution etc.
·
Secondary Notification is delivered to the users in
the Notification Area even under congestion situation.
-
ETWS Primary Notification has
higher priority than Secondary Notification i.e., the notifications shall be
able to be sequenced by the PLMN according to priority of notification in case
that both notifications should exist at the same time in PLMN.
Commercial
Mobile Alert System (CMAS) is a public warning
system developed for the delivery of multiple, concurrent warning notifications.
These messages include CMAS Presidential Level
Alerts, CMAS Child Abduction Emergency (e.g. AMBER), Imminent Threat, Public
Safety etc…
Paging is used to inform UEs about ETWS and CMAS indications.
UE monitors ETWS/CMAS indications in its own paging occasion for RRC_IDLE and
RRC_INACTIVE and in any paging occasion for RRC_CONNECTED.
Paging indicating ETWS/CMAS notification triggers
acquisition of system information (without delaying until the next modification
period).
Different SIBs are defined for ETWS primary
notification, ETWS secondary notification and CMAS notification. The following
table provides the summary;
SIB Type
|
SIB Contents
|
SIB6
|
ETWS primary notification
|
SIB7
|
ETWS secondary notification
|
SIB8
|
CMAS warning notification
|
General
Information
SIB6,
SIB7 and SIB8 are mapped to BCCH logical channel and is either broadcast
periodically on DL-SCH or broadcast on-demand on DL-SCH (i.e. upon request from
UEs in RRC_IDLE or RRC_INACTIVE) or sent in a dedicated manner on DL-SCH to UEs
in RRC_CONNECTED.
SIB6,
SIB7 and SIB8 are carried in SystemInformation (SI) messages,
which are transmitted on the DL-SCH. SIB1 contains scheduling
information for SI-message carrying corresponding SIB. For more information about
scheduling of SI-messages, refer to 5G NR: System Information.
SIB6,
SIB7 and SIB8 can be configured to be cell specific or area
specific, using an indication in SIB1. The cell specific SIB is
applicable only within a cell that provides the SIB while the area
specific SIB is applicable within an area referred to as SI area, which
consists of one or several cells and is identified by systemInformationAreaID.
System
Information Block 6 (SIB6)
SIB6 contains
an ETWS primary notification. ETWS primary notifications are meant contain
small data/information in order to facilitate quicker delivery.
Overview
of SIB6 contents presented below;
| SIB6 |
|
| messageIdentifier |
BIT STRING ( SIZE (16) ) |
| serialNumber |
BIT STRING ( SIZE (16) ) |
| warningType |
OCTET STRING ( SIZE (2) ) |
messageIdentifier identifies
the source and type of ETWS notification using 16-bit string. Different message
identifiers are defined for PWS in section 9.4.1.2.2 from 23.041. For example,
hex value 1100 indicates Tsunami warning message, 1101 indicates Earthquake
warning message, 1102 indicates Tsunami and Earthquake combined warning message
and so on.
serialNumber identifies
variations of an ETWS Primary Notification. This parameter identifies a
particular ETWS Primary Notification message from the source and type indicated
by the Message Identifier and is altered every time the ETWS Primary
Notification message with a given Message Identifier is changed.
warningType identifies
the warning type of the ETWS primary notification and provides information on
emergency user alert and UE popup. It has three fields warning type value,
emergency user alert and popup indications. The encoding of the
Warning-Type parameter is as shown below.
Octet 1
|
Octet 2
|
7
|
6
|
5
|
4
|
3
|
2
|
1
|
0
|
7
|
6
|
5
|
4
|
3
|
2
|
1
|
0
|
Warning Type Value
|
|
|
Padding
|
|
|
|
|
|
|
|
|
|
Emergency User Alert |
|
|
|
|
|
Popup |
The
warning type value field is expressed as 7-bit string. The following table
shows the values and their corresponding warning types.
Warning typeValue
|
Warning type
|
0 0 0 0 0 0 0
|
Earthquake
|
0 0 0 0 0 0 1
|
Tsunami
|
0 0 0 0 0 1 0
|
Earthquake and Tsunami
|
0 0 0 0 0 1 1
|
Test
|
0 0 0 0 1 0 0
|
Other
|
0 0 0 0 1 0 1 — 1 1 1 1 1 1 1
|
Reserved for future use
|
The
fields for emergency user alert and popup indications are type binary. They are
used to command UEs to activate emergency user alert and message popup in order
to alert the users upon the reception of ETWS primary notification (e.g. paging
message). The fields are as shown below;
Value
|
Instruction to the UE
|
Emergency User Alert
|
Popup
|
0
|
No instruction as to Emergency alert
|
No instruction as to Popup
|
1
|
Activate Emergency user alert
|
Activate Popup on the display
|
System
Information Block 7 (SIB7)
SIB7
contains an ETWS secondary notification. ETWS secondary notification convey a
large amount of data in order to deliver text, audio to instruct what to
do/where to get help, graphical data such as a map indicating the route from
present position to evacuation site, timetable of food distribution etc.
Overview of SIB7
contents presented below;
| SIB7 |
|
| messageIdentifier |
BIT STRING ( SIZE (16) ) |
| serialNumber |
BIT STRING ( SIZE (16) ) |
| warningMessageSegmentType |
ENUMERATED {notLastSegment, lastSegment} |
| warningMessageSegmentNumber |
INTEGER (0 … 63) |
| warningMessageSegment |
OCTET STRING |
| dataCodingScheme |
OCTET STRING ( SIZE (1) ) |
messageIdentifier identifies
the source and type of ETWS notification using 16-bit string. Different message
identifiers are defined for PWS in section 9.4.1.2.2 from 23.041. For example,
hex value 1100 indicates Tsunami warning message, 1101 indicates Earthquake
warning message, 1102 indicates Tsunami and Earthquake combined warning message
and so on.
serialNumber identifies
variations of an ETWS Secondary Notification. This parameter identifies a
particular ETWS Secondary Notification message from the source and type
indicated by the Message Identifier and is altered every time the ETWS Secondary
Notification message with a given Message Identifier is changed.
warningMessageSegmentNumber
provides the segment number of the ‘ETWS
warning message segment’ contained in the SIB. A segment number ‘zero’
corresponds to the first segment, a segment number ‘one’ corresponds to the
second segment, and so on.
warningMessageSegment
carries a segment of the actual Warning Message Contents
IE.
warningMessageSegmentType
indicates whether the included ETWS warning message
segment is the last segment or not.
dataCodingScheme identifies
the alphabet/coding and the language applied variations of an ETWS
notification. One octet long Data Coding Scheme indicates the intended handling
of the message at the MS, the character set/coding, and the language (when
applicable). The field is mandatorily present in the first segment of SIB7
and is absent otherwise.
System Information
Block 8 (SIB8)
SIB8 contains
a Commercial Mobile Alert Service (CMAS)
notification. Overview of SIB8
contents presented below;
| SIB8 |
|
| messageIdentifier |
BIT STRING ( SIZE (16) ) |
| serialNumber |
BIT STRING ( SIZE (16) ) |
| warningMessageSegmentType |
ENUMERATED {notLastSegment, lastSegment} |
| warningMessageSegmentNumber |
INTEGER (0 … 63) |
| warningMessageSegment |
OCTET STRING |
| dataCodingScheme |
OCTET STRING ( SIZE (1) ) |
| warningAreaCoordinatesSegment |
OCTET STRING |
messageIdentifier identifies
the source and type of CMAS notification using 16-bit string. Different message
identifiers are defined for PWS in section 9.4.1.2.2 from 23.041.
serialNumber identifies
variations of CMAS Notifications. This parameter identifies a particular CMAS
notification message from the source and type indicated by the Message
Identifier and is altered every time the CMAS Notification message with a given
Message Identifier is changed.
warningMessageSegmentNumber
is the segment number of the CMAS warning message
segment contained in the SIB. A segment number ‘zero’ corresponds to the first
segment, ‘one’ corresponds to the second segment, and so on. If warning area
coordinates are provided for the warning message, then this field applies to
both warning message segment and warning area coordinates segment.
warningMessageSegment
carries a segment, with one or more octets, of the Warning
Message Contents IE defined in 38.413. The first octet of the Warning
Message Contents IE is equivalent to the first octet of the CB data IE
defined in and encoded according to section 9.4.2.2.5 of 23.041, and so on.
warningMessageSegmentType
indicates whether the included CMAS warning message
segment is the last segment or not. If warning area coordinates are provided
for the warning message, then this field applies to both warning message
segment and warning area coordinates segment.
warningAreaCoordinatesSegment:
If present, this field carries a segment, with one or more octets, of the
geographical area where the CMAS warning message is valid. The first octet of
the first warningAreaCoordinatesSegment is equivalent to the first octet
of Warning Area Coordinates IE defined in and encoded according to 23.041 and
so on.
dataCodingScheme identifies
the alphabet/coding and the language applied variations of a CMAS notification.
One octet long Data Coding Scheme indicates the intended handling of the
message at the MS, the character set/coding, and the language (when applicable).
The field is mandatorily present in the first segment of SIB8 and is
absent otherwise.
Reference: 3GPP TS 38.331, 22.268, 38.413 and 23.041
