eCall Days Germany 2017 Sept. 19-20, Hamburg, …€“ Increasing 4G VoIP coverage (even beyond 2G/3G coverage) ... – Using IMS Emergency Services requires only small enhancements

Ralf Weber

eCall Deployment Aspects – Today and Tomorrow

eCall Days Germany 2017 Sept. 19-20, Hamburg, Germany

2 Standards & Industry Organizations (QSIO)

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Outline

Introduction Network Coverage Challenge PSAP Conformity Assessment Challenge IMS eCall Challenge Conclusions


Introduction


Introduction eCall – Save Lives in an Emergency

Goal – eCall should allow emergency organizations for faster response times by providing

automatic and manual calls in case of an incident

Typical use case – Car crash in rural or urban outdoor environments

eCall requires mobile network coverage for TS12 emergency services – Voice services have the most reliable performance in todays networks – Call prioritization of TS12 emergency services are guaranteed by networks operators

Caveat

– Network operators have to provide emergency services only in regions where they have network coverage

– Network coverage is a design criteria determined by commercial considerations and regulatory requirements

– Network availability highly depends on type and placement of antenna systems


eCall Transmission Chain

Our main focus


Mobile Network Coverage Challenge


Cellular Network Concept

Source: GSMA

A network consists of base stations covering limited areas (cells) Coverage continuity is achieved by partially overlapping cells Devices determine best suited cells based on receive power measurements


Coverage Example – Urban Area

Areas of weak or no 112 service


Coverage Example – Rural Area

Example taken from https://www.vodafone.co.uk/explore/network/uk-coverage-map/index.htm

Regions of outdoor-only coverage can span several km

https://www.vodafone.co.uk/explore/network/uk-coverage-map/index.htm


-106 -105 -104 -103 -102 -101 -100 -99 -980

5

10

15

20

25

30

35

40

45

RSSI [dBm]

BLE

R [%

]

MSD successMSD failed

Expected IVS Performance Weak Coverage Environment

Weak Speech

Good Speech

Good RF Weak RF

Small number of MSD failures at low RSSI + high BLER

Measured MSD successes after successful call

setup


Simplified Cell Border Scenario Network planning case for outdoor coverage

Cell A Cell B

RX Power Cell B RX Power Cell A HO/reselection

region

HO/reselection threshold

Min. required RX power

Cell A out-of-service Cell A service area

IVS served by

Cell A


Simplified Cell Border Scenario Good Case: External antenna

Cell A Cell B


region




IVS looks for better

cells



Cell A Cell B


region




IVS reselects to Cell B



Cell A Cell B


region




IVS served by

Cell B


Simplified Cell Border Scenario Propagation loss due to in-car antenna placement

Cell A Cell B


region


Min. required RX power IVS cannot make a

call

Coverage hole

Propagation loss Propagation loss


PSAP Conformity Assessment Challenge


PSAP Conformity Assessment Part of Delegated Regulation

Delegated Regulation (EU) No 305/2013 states that conformity assessment shall be based on CEN EN 16454

– Conformity to CEN EN 16454 only includes protocol conformance but does not include performance requirements

I_HeERO Conformity Assessment working group provided suggestions for

– eCall PSAP Component Conformance tests (mandatory) – eCall PSAP Component Performance tests (optional) – Suitability for use tests of PSAP integration (optional)

According to EU decision No 585/2014/EU, member states have to demonstrate PSAP conformity by Oct. 1, 2017

– Final draft ready since Feb. 22, 2017


PSAP Conformity Assessment (cont’d) Performance Challenge

Conformity assessment is not sufficient to ensure proper eCall handling if performance aspects are excluded

– I_HeERO proposed key performance indicators (KPIs) to assess the quality of the PSAP equipment

– Current I_HeERO KPIs allow different quality categories • “High quality” • “Standard” • “Basic”

– The given KPIs for each category do not consider a thorough failure investigation to assess their root cause

Qualcomm had shown in lab environments and in European-wide field test campaigns (15 countries and 45 mobile networks employing more than 50000 calls) that the performance should be better than the I_HeERO KPIs

– MSD Success rates of >99% and average channel blocking <6s should be achievable


PSAP Conformity Assessment (cont’d) Performance Challenge

eCall transmission chain is complex – Reasons for MSD transmission failures can be multifold and caused by either IVS,

network or PSAP deficiencies eCall call setup performance should be very high as 112 emergency calls are

prioritized in mobile networks – Call setup of test calls could be slightly lower but should still be in the range of >99% in

optimized networks

Performance assessment requires careful investigation – Mobile network and eCall expert knowledge needed in order to separate the root cause

of failures Tests are ideally conducted on component level of PSAP in-band modem

– Investigation of eCall HLAP, mobile network protocol as well as audio signals needed

Current KPIs defined in I_HeERO appear to be too conservative and may mask PSAP implementation issues

– Moreover, the given quality categories allow Member States to have different eCall performance criteria, which suggests that some Member States care more than others


IMS eCall Challenge


IMS Network Availability Aspects 4G network deployments increase but still lack coverage in certain regions

– IMS eCall standard is ready since finalization of 3GPP Rel. 14 beginning of 2017 – IMS emergency call capability over VoIP is not yet commonly available – IVS can use CS fallback (CSFB) to transition to 2G/3G for making an in-band eCall

Mobile network operators (MNO) are continuously expanding their networks – Replacing infrastructure with newer standard revisions – Refarming frequency bands from 2G to 3G in order to benefit from higher capacity – Increasing 4G VoIP coverage (even beyond 2G/3G coverage) – Decommissioning of 2G networks are finalized or planned in some regions of the world

Availability of mobile emergency calls is determined by the coverage overlay of all available networks in the incident area

– IVS performs domain selection based on supported technologies

3GPP provides interworking mechanisms to handle the migration phase, e.g. – Only 4G networks are available but no IMS eCall capable PSAP – A handover from 4G to 2G/3G happens after an IMS eCall was established due to lack

of 4G coverage (e.g. car drives out of 4G coverage)


Example: 2G/3G Mobile Network Coverage

Source: https://opensignal.com (data from Jul 27, 2017)

Hamburg harbor area – Measured signal strength by mobile phones in all available 2G/3G networks

Weak 2G/3G spots

https://opensignal.com/


Example: 4G Mobile Network Coverage

Source: https://opensignal.com (data from Jul 27, 2017) Good 4G spots

Hamburg harbor area – Measured signal strength by mobile phones in all available 4G networks




2G Mobile Network Closures Australia

– Telstra: Dec 2016 – Optus: April 2017 – Vodafone: Sept. 2017

Singapore – Singtei, Starhub: Apr. 2017

USA – AT&T: Dec 2016 – Bell/Telus: May 2017 – Verizon: Dec 2019 (planned) – T-Mobile: Dec 2020 (planned)

Taiwan – Chungwa, FET, Taiwan Mobile: Dec 2017

Europe – Swisscom, Switzerland: Jan 2021 (planned) – Sunrise, Switzerland: Dec 2018 (planned) – T-Mobile, NL: Dec 2020 (planned) – Telenor, Norway: Dec 2025 (planned)

Source: Virgin Mobile

Source: Ericsson


MSD in

MSD out

eCall for Future Networks

Speech

Data

IVS MNO FNO PSAP

PS-Domain

PS-Domain

VoIP GW

Speech

Data

VoIP GW

Recommended by ETSI – Using IMS Emergency Services requires only small enhancements to support eCall – Provides end-to-end resource reservation and call prioritization

IMS eCall 3GPP

IETF

CEN ETSI S

cope


eCall Standardization Status 3GPP (3rd Generation Partnership Project)

– Covers mobile communication aspects for IMS in Rel. 14 – Emergency call requirements for IMS – done – IMS eCall requirements and migration from CS eCall – done

IETF (Internet Engineering Task Force) – Covers internet protocol (IP) aspects – ‘additional-data’ specification (RFC 7852) - done – ‘NG eCall’ specification (RFC 8147) - done

ETSI (European Telecommunication Standards Institute) – TR 103 140 recommends to use 3GPP and IETF for eCall – done – TS 103 412 eCall end-to-end and in-band modem conformance testing – stable – TR 103 543 In-Vehicle Systems Guidelines for IVS conformity assessment – stable

CEN (Comité Européen de Normalisation) – EN 16072 (eCall requirements) applies to in-band and IMS eCall – no change needed – EN 16062 (HLAP) equivalent Work Item 00278452 - positive vote, awaiting publication – EN 16454 (HLAP testing) equivalent Work Item 00278460 - awaiting TC278 comment – eCall for other categories of vehicles Work Item 00278466 - awaiting TC278 comment


Conclusions


Conclusions Network Considerations

Voice/TS12 emergency calls – Networks are configured to prioritize all emergency calls – Voice services are typically the best optimized by operators – Call setup and retention performance for eCall are the same as for normal voice/TS12

calls

Network coverage (managed by operators) – Urban areas: Network optimized for indoor and outdoor scenarios – Rural areas: Network optimized for outdoor scenarios (may include in-car scenario) – Typical network planning parameters:

• Indoor propagation loss: 20 dB • In-car propagation loss: 10 dB • External antenna gain: 3-6 dBd

eCall performance – eCalls experience performance degradations when coverage gets weak – eCalls have been shown to be reliable even at BLER values exceeding coverage target

for voice/TS12 – Service continuity of emergency calls can only be achieved if device integration is

following the typical use case scenario assumed by operators, i.e. outdoor or in-car


Conclusions (cont’d) IVS Considerations

The issue of antenna placement in the car (e.g. IVS embedded antenna) – In-car propagation loss can reach ≥20dB in modern cars (e.g. due to shielded windows) – Reduced cell coverage can lead to call setup failures or call drops in cell border areas

GNSS performance

– Similar considerations apply for GNSS antenna systems – Combination of 2G/3G and GNSS antennas possible – Position accuracy requirements that are currently defined for eCall on EU and UN level

will be challenging to achieve using internal antennas

Recommendations – Integrated external antenna system gain should achieve typical minimum 3dBd or more

• Use of only internal antennas is highly discouraged – Considering the long life time of vehicles, new IVSs should support 2G/3G/4G with both

CS and IMS eCall in order to avoid call failures due to lack of network coverage – Car type-approval regulation should consider to include

• antenna requirements to avoid implementation deficiencies leading to performance impacts • ‘common best practice principles’ to accommodate technology evolutions


Conclusions (cont’d) PSAP Considerations

PSAP conformity assessment should also include performance tests – Careful investigation of failure causes can reveal PSAP implementation issues – It is recommended that all Member States ensure “high quality” performance

PSAPs should retain in-band capability as long as CS networks and CS IVSs exist – Ensures increased network coverage and thus the chance to setup an eCall – However, PSAPs should consider to make provisions now such that they can easily

upgrade to IMS later Even if PSAPs are upgraded to support IMS eCall, then they should still continue

to support CS eCall for legacy devices and 4G coverage border scenarios – An IMS eCall broadcast flag is proposed to instruct dual-mode IVS to place an eCall over

IMS when this is supported end-to-end by the network and the PSAP IMS eCall introduction will happen only gradually over time, when MNOs upgrade

their networks with IMS emergency services based on economic considerations – It is not expected that IMS eCall will be mandated in the near future because it would

mean a huge investment for MNOs and PSAP operators – IMS eCall leverages commercial IP/SIP based protocols and equipment, reducing

investment upgrade costs (especially when ISDN lines gets replaced by all IP lines)


Thank You ! Questions?

Contact: - Ralf Weber (rweber @ qualcomm.com)

mailto:[email protected]

Documents

eCall Days Germany 2017 Sept. 19-20, Hamburg, …€“ Increasing 4G VoIP coverage (even beyond 2G/3G coverage) ... – Using IMS Emergency Services requires only small enhancements