EENA Conference 2017 session

1. Proprietary + ConfidentialProprietary + Confidential
Proprietary + ConfidentialGoogle Proprietary + Confidential
Android Emergency
Location Service
Akshay Kannan
Steve Malkos

2. Google Proprietary + Confidential
Emergency Location
Service (ELS) for
AndroidSend supplemental AML locations directly
from all existing Android handsets to
emergency services
• Just works- no opt-in or app install
required
• > 99% of existing Android phones
support this already today
• Easy to integrate with- emergency
services provide endpoint

3. Source: Lorem ipsum dolor sit amet, consectetur adipiscing elit. Duis non erat sem
Google Proprietary + Confidential
Motivation and Design Principles
Save Lives Privacy-first design Available Everywhere
Google does not profit from this
project or obtain any PII. The goal
is to keep our users safer and
improve the state of emergency
services around the world.
Location is computed locally and
sent directly from the handset to
operator (never through Google
servers). It can only be initiated by
a user explicitly placing an
emergency call.
Present on > 99% of Android
devices through Google Play
services. No action or update
required by the user.

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Google Proprietary + Confidential
Android ELS Deployment Status
• Serves ~76 million people, with a daily
volume of ~20,000 calls/day and ~90%
location yield.
• Undergoing testing and evaluation in
many more countries internationally
Live Testing

5. Google Proprietary + Confidential
July 2016 - Estonia
• Children home alone with toaster
on fire
• Knew their flat number and street
name but not the complete
address
• Call-taker used location from ELS
to find the right house
• Estonian 112 gave dispatch order
to rescue and ambulance units
who arrived quickly

6. Google Proprietary + Confidential
Jan 2017 - Austria
• Mountain biker in Austria suffered a
serious accident in a heavily forested
area
• No landmarks in sight and no address
information available for the call
• Cell tower radius > 900m
• ELS able to deliver a location with a
12m radius and guide first responders to
the exact scene.

7. Google Proprietary + Confidential
Jan 2017 - Lithuania
• 8-year old boy reported he had found his
father unconscious or dead, probably
struck by electricity
• Didn’t know address or telephone
number of any relatives
• Cell location radius of 14km
• ELS delivered with a radius of 6m
• Emergency responders able to provide
acute medical care to the man who had
likely been struck by an epileptic seizure
MNO location
14km radius
ELS location
6m radius

8. Google Proprietary + Confidential
Emergency Event Flow
Partner
Endpoint
PSAP112
Emergency call
initiated by Android
device
Location computed
on device using FLP
Location relayed to emergency services through
a centralized endpoint, maintained by partner

9. Google Proprietary + Confidential
How is Location Computed?
Fused Location Provider
The Fused Location Provider (FLP) computes
location when a call is made to a configured
emergency number. The FLP combines GPS, cell
and Wi-Fi location technologies, and other sensors to
derive highly accurate indoor and outdoor location.
All Android devices receive regular updates to FLP
through Google Play Services.
Cell
Position 164
Meters
A-GPS
Position
106 Meters
Google FLP
16.8 Meters

10. Google Proprietary + Confidential
Indoor Test Results
Yield 67th Percentile
Error
90th Percentile
Error
AGPS 63.11% 43m 107m
Cell 36.89% 154m 165m
FLP 90.2% 17m 18m
AGPS Cell FLP
Tier 1 US Carrier - 100 calls
● Adopting ELS in the coming months
meters

11. Google Proprietary + Confidential
UK Live Deployment Results
Help112- Study by British Telecom
● Caller location from ELS is very reliable, precise
and accurate using either GNSS or Wi-Fi.
● Search area is reduced from an average of 12km2
to around 0.004km2
● Overall the current split in positioning method is:
○ 42% WiFi
○ 37% GNSS
○ 7% Cell
○ 13% No Location
● 89% “good” location yield
Accuracy
No location 13%
0-9m 17%
10-19m 35%
20-49m 23%
50-99m 6%
100-999m 4%
999+m 2%

12. Google Proprietary + Confidential
How is Location Reported?
We partner with operators or other entities already responsible for handling
emergency location in a given region. The partner is responsible for implementing
an endpoint which can receive location directly from handsets that are making
emergency calls.
Endpoint types:
● Data SMS
● HTTPS
Carrier PSAP112
Mobile Phone

13. Google Proprietary + Confidential
Data SMS Endpoint
A data SMS is subset of the SMS standard that is addressed to a specific port on
a device, and allows for a binary payload. This does NOT transmit over data
connection, and has nothing to do with a data connection in general.
Definition? The UserDataHeader segment of the SMS is present and contains an
application port address InformationElementIdentifier.
Why Data SMS? Won’t show up in the user’s outbox.

14. Google Proprietary + Confidential
Data SMS Content
Within the Data SMS the message is encoded as 7 bit GSM characters. This
gives us 133 bytes (152 7-bit encoded elements) of space once the extra SMS
header length is taken into account.
What’s in a message? Advanced Mobile Location (AML) information, a standard
proposed by British Telecom and adopted by EENA.
A"ML=1;lt=+55.74297;lg=-4.26880;rd=10;top=20130717175329;lc=95;pm=G;si=234302543446355;ei=356708041746734;mcc=234;mnc=30;ml=127
Header Latitude Longitude Radius Time of
Positioning
Level of
Confidence
Positioning
Method
IMSI IMEI MCC MNC Message
Length

15. Google Proprietary + Confidential
HTTPS Endpoint
A simple HTTPS server that can handle POST requests. Emergency information
is transmitted as a POST request with information in key/value pairs.
Why HTTPS? Can transmit much more information than Data SMS.
Why not HTTPS? Requires a reliable and good data connection and doesn’t
work on CDMA networks.

16. THANK YOU
Team Email: android-emergency-location@google.com
Partner Website: https://goo.gl/x3P1pV