3GPP2 eCall In-band Modem - Considerations AC10-20160112-004 3GPP2 TSG-AC WG1 Teleconference January 12, 2016 3GPP2 eCall In-band Modem - Considerations

Overview History of eCall in 3GPP In-band modem for 3GPP2 PSAPs Requirements from MNOs Limitations of study Selecting, verifying, specifying, implementing, field-testing, and updating in–band modem Lessons Learned In-band modem for 3GPP2 PSAPs Timelines Conclusions

eCall in 3GPP History 2006: GSM Europe completed extensive study of solution framework for eCall signalling “Options for eCall MSD signaling”, GSM Europe Position Paper, April 21, 2006 Studied SMS, User to User Signalling, Unstructured Supplementary Service Data, GSM Circuit-Switched Data, DTMF, In-band Modem/Signalling application Chose In-band Modem: Leveraged use of already being deployed E112 routing to PSAPs for circuit-switched emergency voice calls Packet-Switched/IMS based solution was not considered at the time as support was not yet prevalent “… the initial eCall service must operate in the CS domain, however, a hybrid CS and PS, or PS only, based solution can be expected in the future e.g. when IMS support and VoIP emergency calls become prevalent. SIP signalling and other IP /TCP or UDP solutions for eCall might then be possible. “ The reasons/criteria for choosing an in-band solution in 2006 are no longer valid today 2006: 3GPP set technical requirements/criteria for in-band modem solution 2007: 3GPP began competition for in-band modem selection, including establishing testplan, contracting independent 3rd party testing labs

eCall in 3GPP History (2) 2008: 3GPP completed competition and selection of in-band modem 3GPP Rel-8 specs updated to support eCall identification and routing to a PSAP and avoidance of network signaling for terminals configured for “eCall-only mode” 2009: 3GPP completed verification, characterization, and specification of modem 2011: 3GPP completed significant update to modem specifications based on results of field testing and trials Performance of in-band modem affected by non-standardized voice processing in the network (e.g., network echo-cancelling, noise-suppression, transcoding, proprietary compression algorithms on link between MGWs from the same vendor) through different paths (VoIP backhaul, different vendor MGWs). These effects could not be predicted or simulated when selecting the in-band modem Needed extensive (~ 2 years) field tests and trials to update modem and ensure robust performance

eCall in 3GPP History (3): European Field-Test Campaign 48 Networks in 15 countries 22 stationary locations 12 mobility routes >16000 calls >25000 MSD transmissions Networks by country Countries with 3GPP2/cdma2000 networks cover more than 3x land area of Europe

eCall in 3GPP History (4) 2015: Russia mandated deployment of in-band modem with ERA GLONASS system for all vehicles (9 years after GSME completed study) Russian eCall service is still not yet commercially deployed as of January 2016 (~10 years later) 2018: European Union mandated deployment of in-band modem in vehicles Still On-going: development of comprehensive certification program for eCall system: vehicles, mobile network, PSAPs

eCall in 3GPP Lessons Learned about In-band Modem Solution Not future proof It has proven not suitable for LTE or any packet-switched access in the presence of voice de-jitter buffering While applicable to GSM and WCDMA, EU operators are expected to migrate to 4G and 5G over the next decade, rendering the solution obsolete Interferes with voice communication During MSD transfer which can occupy 5-10 seconds, the user and PSAP cannot communicate EENA (European Emergency Number Association) regard this as a severe limitation Takes a long time to define, standardize and field-test An in-band voice modem solution requires meticulous design, simulation, and extensive field-testing due to the presence of non-standardized network voice processing implementations which do not cause perceptual degradation in voice quality, but can greatly impact the performance of the in-band modem Costly for PSAPs PSAPs in some EU countries (e.g. UK, France) are expected to delay in-band modem support due to cost Will reduce the effectiveness of eCall (e.g. if routed to a PSAP without support or handling a very large area)

In-band Modem for 3GPP2 3GPP in-band modem solution uses pulse-position-modulation (PPM) to achieve relatively high raw data rate AMR and AMR-WB are waveform coders that maintain pulse positions in the CELP voice model After applying Turbo-channel coding, Hybrid ARQ, and higher-layer START/ACK/NACK protocols, PPM enables transmission of 140 bytes of data within ~ 6 seconds voice channel blocking Competing technologies in 3GPP that used FSK-based modulation had at least 3x slower MSD transmission 3GPP2 EVRC codec is not a waveform coder -> “perceptual coder” To achieve better compression, uses Relaxed-CELP (RCELP) which performs some time-warping of the signal with minimal perceptual distortion Have tested 3GPP in-band modem with EVRC Can not support the 3GPP in-band modem reliably without changes to the EVRC codec in the terminal and network 3GPP2 will need to design a new, incompatible, in-band modem for EVRC If 3GPP2 in-band modem is used for data transmission throughout the call (not just at initiation) then each transmission will disrupt the voice conversations by >6 seconds

Public-Safety Answering Points (PSAPs) Considerations In-band modem solutions Requires upgrade to PSAP to support modem bank Will require network upgrade to identify an eCall and route to an eCall capable PSAP (as in Europe) 3GPP and 3GPP2 (and possibly other air interfaces/vocoders) require different in-band modem versions Multiple modem versions at PSAP Have to distinguish from which network/vocoder the incoming call is coming from, e.g., differentiating trunks Experience in the EU, where even one in-band modem solution has proven too costly for many PSAPs, means that PSAP uptake of a multiple (e.g. dual) modem solution could be very low

eCall Standardization and Deployment Timelines Realistic Estimate for 3GPP2 In-Band Modem 2016 complete study of which eCall technologies (in-band, PS, USSD, SMS, etc…) to develop 2018 complete technical requirements, competition, test plan, selection, verification, and characterization of in-band modem solution 2020 complete field-testing of in-band modem solution, update specifications as needed 2021 terminals ready for deployment 20XX Develop packet-based solution for All-IP networks Develop solutions for migration from in-band to PS-based eCall Manage deployment/migration of PSAPs, mobile networks, and terminals from in-band to PS-based eCall

Conclusions Specifying use of in-band modem technology needs to be carefully studied Solution has limitations and requires extensive selection, verification, field-testing to develop robust solution Other solutions are possible that can be deployed in the same time frame and with less limitations PSAPs Migration to SIP/IP is extensible, evolutionary, provides more features, will be necessary eventually and its complexity should be compared to managing multiple in-band modem upgrades and their management Proposal 3GPP2 evaluate all potential solutions, especially packet-based, and not just in-band modem solution