ETSI TR 103 393 V1.1.1 (2016-03)

Emergency Communications (EMTEL); Advanced Mobile Location for emergency calls

DTR/EMTEL-00035

General Information

• Status: Published
• Publication Date: 28-Mar-2016
• Technical Committee: EMTEL - Emergency Communications
• Current Stage: 12 - Completion
• Due Date: 04-Apr-2016
• Completion Date: 29-Mar-2016

Standards Content (Sample)

ETSI TR 103 393 V1.1.1 (2016-03)






TECHNICAL REPORT
Emergency Communications (EMTEL);
Advanced Mobile Location for emergency calls

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2 ETSI TR 103 393 V1.1.1 (2016-03)



Reference
DTR/EMTEL-00035
Keywords
emergency, location
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3 ETSI TR 103 393 V1.1.1 (2016-03)
Contents
Intellectual Property Rights . 4
Foreword . 4
Modal verbs terminology . 4
Introduction . 4
1 Scope . 5
2 References . 5
2.1 Normative references . 5
2.2 Informative references . 5
3 Abbreviations . 6
4 General Description . 6
4.1 Overview . 6
5 Location transport . 6
5.1 Use of SMS in a single country where a PSAP obtains mobile location from a centralized location
server . 6
5.2 Use of SMS when roaming. 7
5.3 Using a data push across the mobile network . 7
6 Handset Considerations . 8
6.1 Overview . 8
6.2 Process Automation . 8
6.3 Battery Life . 8
6.4 Positioning Methods . 9
6.5 Limited Service State . 10
6.6 Repeat 112 Voice Calls . 11
7 Mobile Network considerations . 11
8 Specification for location message content . 11
9 Conclusions and Recommendations and Future Outlook . 12
Annex A: Location message - SMS format . 14
Annex B: Example AML Messages . 17
Annex C: Overview of AML Implementation in the UK . 18
C.1 General . 18
C.2 Use of SMS in the UK for handsets produced for the UK - current AML implementation . 18
History . 20


ETSI

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4 ETSI TR 103 393 V1.1.1 (2016-03)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Special Committee Emergency Communications (EMTEL).
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
One of the biggest challenges facing the Emergency Services is determining the location of mobile callers. Cell based
location has been available to the Emergency Services for more than 10 years. While cell data can help with verbal
establishment of a caller's location, a more precise location will allow an even quicker emergency response.
Ambulance Service measurements show that, on average, 30 seconds per call can be saved if a precise location is
automatically provided, and several minutes can be saved where callers are unable to verbally describe their location
due to stress, injury, language or simple unfamiliarity with an area. In the UK alone it is estimated that each year there
are about 36 000 cases where the Emergency Services have to spend a significant amount of time searching for a caller
because a location could not be verbally provided.
Advanced Mobile Location (AML) allows use of native smart phone technology to pass (Assisted) GNSS or WiFi
based location data to Emergency Service PSAPs. These technologies can provide a location precision as good as
5 metres outdoors (and averaging to within circular areas of ~25 m radius for indoor locations), a significant
improvement on existing cell coverage provided by mobile networks, which average (across the UK) circular areas of
about 1,75 km radius.
The present document builds on the Advanced Mobile Location initiative that has been piloted in the UK and shown to
improve the precision and accuracy of a caller's location information for emergency calls from mobile handsets.

ETSI

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5 ETSI TR 103 393 V1.1.1 (2016-03)
1 Scope
The scope of the present document is to:
• Consider how AML can be used with different PSAP, and Location Delivery to PSAP, arrangements that exist
in Europe.
• Consider how AML can be extended to cover the case of handsets that roam.
• Optimize the content of a location message to be of most use to the emergency services.
• Provide a reference on AML for administrations, mobile networks and handset manufacturers.
The present document focusses on circuit switched emergency voice calls and location transport via SMS, but provides
an outlook to other technologies suitable the future.
A review of how AML has been implemented in the UK is contained in Annex C.
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or non
specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
https://docbox.etsi.org/Reference/.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or non
specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] IETF RFC 6881: "Best Current Practice for Communications Services in Support of Emergency
Calling".
[i.2] ETSI TS 123 167: "Universal Mobile Telecommunications System (UMTS); LTE; IP Multimedia
Subsystem (IMS) emergency sessions (3GPP TS 23.167)".
[i.3] ETSI TS 124 229: "Digital cellular telecommunications system (Phase 2+); Universal Mobile
Telecommunications System (UMTS); LTE; IP multimedia call control protocol based on Session
Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3 (3GPP TS 24.229)".
ETSI

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6 ETSI TR 103 393 V1.1.1 (2016-03)
3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AML Advanced Mobile Location
BT British Telecommunications
GMLC Gateway Mobile Location Centre
GNSS Global Navigation Satellite System
GPS Global Positioning System
HTTPS Hypertext Transfer Protocol Secure
IMEI International Mobile Equipment Identifier
IMS Internet protocol Multimedia Subsystem
IMSI International Mobile Station Identity
LSS Limited Service State
MAC Media Access Control
MCC Mobile Country Code
ML Message Length
MNC Mobile Network Code
MSISDN Mobile Station International Subscriber Directory Number
NTP Network Time Protocol
PSAP Public Safety Answering Point
SIM Subscriber Identity Module
SIP Session Initiation Protocol
SMPP Short Message Peer to Peer
SMSC Short Message Service Centre
SSID Service Set Identification
TS12 Teleservice 12
UTC Coordinated Universal Time (literally Universel Temps Coordonné)
WGS84 World Geodetic System 1984
XML Extensible Markup Language
4 General Description
4.1 Overview
AML functionality is triggered by a TS12 emergency call (which is unaffected), and is designed to supplement the basic
network location feed wherever possible, i.e. with some acknowledgement of limitations in GNSS or WiFi availability
for the handset and the time required to acquire location using GNSS.
Location information established by the handset, using its built-in GNSS and WiFi connectivity, together with user
plane assistance data from a handset-selected service where available, is transported (e.g. through use of SMS) to the
emergency service PSAPs.
Handset locations obtained through the AML functionality are compared to the location provided by mobile network
GMLCs (currently using basic cell coverage information), using an algorithm that analyses factors such as time of
positioning and the separation of the two locations. This is to validate any handset location information provided, to
ensure it is consistent with the network location.
It is important that AML does not interfere with the voice call so both the handset and mobile network should be
TM
configured to be able to simultaneously support a standard 3GPP mobile emergency voice call, location determination
using GNSS/WiFi capabilities and SMS transmission of the location over the 3GPP mobile network.
5 Location transport
5.1 Use of SMS in a single country where a PSAP obtains
mobile location from a centralized location server
When the location is determined by the device it can be sent using a simple SMS message.
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7 ETSI TR 103 393 V1.1.1 (2016-03)
SMS offers the widest possible geographic coverage, especially in remote areas, is reliable to a fixed destination and is
robust - if a voice emergency call can be made an SMS is also possible. SMS is a store and forward service and
therefore instantaneous delivery is not guaranteed. However, in a current AML implementation, SMS from a mobile to
a fixed location offers reliable performance.
SMS emergency location messages should not be charged to end users.
NOTE: Zero rate billing is already applied by mobile networks to SMSs to 112 in some countries.
An SMS message is initially routed to the home network's SMSC. SMSCs should be programmed to send an emergency
location SMS (identified by an SMS number such as 112, or a dedicated full length MSISDN of the PSAP) via an SMS
gateway to a server operated by, or on behalf of, the PSAP that is running an AML location processing application (the
AML Server). The AML Server compares the information from the handset with location information from the mobile
network for the MSISDN of the emergency caller, before making it available to the PSAP's existing location server. An
example of this currently used in the UK is shown in clause C.1.
Resilience of the servers and the interconnecting links should meet national targets.
5.2 Use of SMS when roaming
If an end user from country A roams to another European country (country B), and makes a 112 call, then the 112 voice
call is routed to a local PSAP in visited country B, but the SMS is returned to the SMSC in country A for routing.
If 112 was used as destination for the emergency location SMS, the SMSC in country A would simply direct it to the
AML Server in country A where it cannot currently be used (no path to AML Server in visited country B).
The visited country in which the mobile handset is operating can be determined by the handset using the Mobile
Country Code (MCC) component of the current serving cell ID. The mobile handset also has information about the
Mobile Network being used (e.g. for charging information) and the cell information.
One option is for the mobile handset to then look-up an SMS number (in a regularly updated handset database) to which
to route the emergency location SMS specific to the visited country - as long as this is a full length MSISDN the home
country SMSC should then be able to route it to the visited country's location processing server (i.e. the AML Server in
country B). Charging arrangements between mobile networks should be agreed to zero rate such SMS messages for end
users.
Which server can be selected to be the visited country's location processing server will be dependent on the current
infrastructure within that country - in some cases it could be a server within the PSAP that already receives the GMLC
network location information from mobile networks, which will need to be upgraded to receive the content of the AML
SMS.
A second option is that if it is not possible to use a full length MSISDN for each country, then where the AML Server in
country A does have links to other countries across Europe, the Mobile Country Code and Mobile Network Code should
be used to forward the AML information from the AML Server in the home country (country A) to the PSAP's AML
Server/location processing server in the visited country.
5.3 Using a data push across the mobile network
Data push across a mobile network is an alternative option to using SMS transport that may also be adopted if the data
connectivity is considered to be sufficiently widespread and reliable to use instead. It relies on end users having a data
subscription and for data to be enabled in the handset. There is also a limitation in that roaming users are likely to
disable use of data to avoid roaming charges. This method currently has the disadvantage that data cannot be zero rated.
The visited country in which the mobile handset is currently operating can be determined using the Mobile Country
Code (MCC) component of the current serving cell ID. This is sufficient for the handset [in a regularly updated handset
database] to identify the URL for a national location processing server to which data may be pushed using an HTTPS
message, using the same data elements as in the SMS message, probably using XML within the HTTPS message.
In some countries a national server approach is sufficient, as PSAPs operate at the national level (as in Stage 1 PSAP in
the UK), or there are national location processing servers which regional PSAPs can all access. In other countries with
regional PSAPs it poses additional challenges.
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8 ETSI TR 103 393 V1.1.1 (2016-03)
There are differing approaches to solving this challenge depending on whether the data is pushed to the PSAP or pulled
by the PSAP, and what are the existing emergency location server arrangements (regional or national servers). Options
are that:
• All PSAPs, regional or otherwise, pull from a national emergency location server.
• Establish a hierarchy of proxy-servers that reside inside each PSAP region. If the location data should be
maintained within the regional jurisdiction of the PSAP, then the national server should be able to identify the
correct regional proxy server to push the data to, and then subsequently push it. Requests can then made by the
regional PSAP (probably using the originating device's telephone number/MSISDN as a key) to pull location
from the regional proxy-server. (If the regional proxy-server has not had location pushed to it from the national
server it may subsequently request information from a national server.)
6 Handset Considerations
6.1 Overview
This clause focusses on using SMS as transport for the emergency location information due to current limitations of
other methods discussed in clause 5.
6.2 Process Automation
The software should be integrated with all existing emergency call mechanisms available on the handset including
manual selection of 112 digits (or any national emergency numbers such as 999 in the UK), or use of an Emergency
Call button.
The use of AML software should be dependent on the Mobile Country Code and Mobile Network Code identified by
the handset, to help allow a managed rollout of AML.
In an eme
...