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Hannu Hietalahti Kevin Holley Stephen Hayes Brian Daly

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Presentation on theme: "Hannu Hietalahti Kevin Holley Stephen Hayes Brian Daly"— Presentation transcript:

1 Hannu Hietalahti Kevin Holley Stephen Hayes Brian Daly
IETF #79, 7 – 12 Dec, 2010, Beijing, China PWS Public Warning System Hannu Hietalahti Kevin Holley Stephen Hayes Brian Daly

2 Contents Cell Broadcast Service Overview Current status of PWS
PWS Service requirements Cell Broadcast Service PWS Technical overview Use case Details Extensibility Message Identifiers Regional Standards CMAS architecture and call flow example Summary

3 Current status of Public Warning System
PWS comprises public alert services in 3GPP Earthquake and Tsunami Warning System ETWS (Rel-8) Commercial Mobile Alert System CMAS (Rel-9) EU-Alert requirements are being studied (Rel-11) Global service Warning categories must be defined globally Detection of the warning categories must be global for roaming users Applicable in 3GPP systems over GSM, UTRAN and LTE radio Specification references Stage 1 in 3GPP TS (Requirements) Stage 2 in 3GPP TS (CBS, Message Identifier coding) Stage 3 in 3GPP TS , , , , , (Radio interface)

4 Service requirements (from 3GPP TS 22.268)
Broadcast Warning Notifications to multiple users simultaneously Geographical notification area is specified by the Warning Notification Provider Roaming subscribers must be supported Concurrent broadcast of multiple Warning Notifications with no acknowledgement required PWS capable terminals in idle mode shall be able to receive broadcast warnings User may opt-out from certain alert categories Warning Notifications languages are determined by regulatory requirements Warning Notifications are processed by PWS on a first in, first out basis, subject to regulatory requirements Reception and presentation of Warning Notifications to the user shall not pre-empt an active voice or data session. Current implementation requirement is up to 90 7-bit characters Typical contents of the warning: Event Description Area Affected Recommended Action Expiration Time (with time zone) Sending Agency

5 Cell Broadcast Service (CBS)
CBS is defined in 3GPP TS23.041 CBS can cover different services that are independent of each other PWS uses CBS in GSM and UTRAN In LTE the messages are encoded according to CBS rules, but distribution at the radio interface is LTE specific Unacknowledged broadcast to all CBS-capable mobiles within a particular region defined geographical areas known as cell broadcast areas may comprise of one or more cells, up to the entire network CBS messages may originate from a number of Cell Broadcast Entities (CBEs) through an operator’s Cell Broadcast centre (CBC) CBS messages are sent from the CBC to the cells, in accordance with the CBS's coverage requirements Maximum capacity ranges from GSM 93 7-bit characters to LTE 316 characters Message segmentation is possible (15 – 64 segments) A CBS message is identified by a message identifier and serial number Can be used by the mobile to “screen” which messages are received Also to identify and ignore re broadcasts of already received messages 3GPP manages the message identifiers CBS messages may be broadcast cyclically by the cell at a frequency and for a duration agreed between the operator and the information provider

6 Technical overview, use case (Figure from 3GPP TS 22.268)
Key points: Interface provided to Government authority to submit alert messages Government authority is responsible for interface to and authentication of alert originators Security against fake alarms, operator must authenticate alert issuer at interface C Support for all terminals in the affected geographical area, including roaming users and terminals sourced from other countries Distribution mechanisms at radio interface differ between GSM, UTRAN, LTE but are all based on broadcast mechanisms

7 Technical overview, details
Radio procedures for broadcasting in 3GPP radio access technologies Common paging or SysInfo change or CBS Distribution area Geographical selectivity is based on network topology Alert codes are globally defined Detection of alert categories is not restricted to physical distribution channel at radio interface but part of PWS service Paging to wake up the terminal to listen to broadcast information Mutual authentication to avoid MiM and playback attacks Data coding scheme is critical for compatibility and mobility Message Identifier corresponds with alert category Message Identifiers to be received can be pre-configured on USIM or by the user Language code Default 7-bit coding with several language specific extensions or 16-bit UCS2 coding for other languages Sequencing to distinguish between different messages

8 PWS extensibility Message identifier ranges are assigned for different broadcast use cases MI 0 – 999 are defined by GSMA for Flash messages, weather reports, traffic reports, date & time, etc MI are defined by 3GPP for specific services, among them PWS MI values 1100 – 18FF are reserved for PWS use More than 2000 code points not assigned yet ME application configures the reception of the MIs related with the service Reception of any MI can be configured on USIM by the HPLMN operator Legacy terminal processing of unforeseen data is normatively specified and thus predictable alert category, character set, broken sequence, etc. All alert categories shall be globally unique National or regional exceptions cannot change the meaning of alert code Japanese Tsunami alert code cannot be re-used for avalanche warning in Switzerland CMAS Presidential Level Alert code point can be re-used for EU-Alert 1 Additions to existing codes are possible National extensions must be defined globally

9 Message Identifiers (3GPP TS 34.041)
Decimal Hex Meaning 0 – 999 0000 – 03E7 Allocated by GSMA (see GSMA PRD SE.15 http://gsmworld.com/documents/SE15330.pdf ) ... 4352 1100 ETWS CBS Message Identifier for earthquake warning message. 4353 1101 ETWS CBS Message Identifier for tsunami warning message. 4354 1102 ETWS CBS Message Identifier for earthquake and tsunami combined warning message. 4355 1103 ETWS CBS Message Identifier for test message. Normal UE silently discards this message. Test UE may may display its contents. 4356 1104 ETWS CBS Message Identifier for messages related to other emergency types. 4357 – 4359 ETWS CBS Message Identifier for future extension. Intended for standardization in future versions of this document. These values shall not be transmitted by networks that are compliant to this version of this document. If a Message Identifier from this range is in the "search list", the ME shall attempt to receive this CBS message. 4370 1112 CMAS CBS Message Identifier for Presidential Level Alerts. Not settable by MMI. 4371 1113 CMAS CBS Message Identifier for Extreme Alerts with Severity of Extreme, Urgency of Immediate, and Certainty of Observed. Settable by MMI as per CMAS subscriber opt-out requirements 111F-112F CMAS CBS Message Identifier for future extension. 1130 – 18FF CBS Message Identifier for future PWS use. These values shall not be transmitted by networks that are compliant to this version of this document. If a Message Identifier from this range is in the "search list", the ME shall attempt to receive this CBS message. 6400 – 40959 1900 – 9FFF Intended for standardization in future versions of this document . These values shall not be transmitted by networks that are compliant to this version of this document. If a Message Identifier from this range is in the "search list", the ME shall attempt to receive this CBS message.

10 Regional Standards ETWS, CMAS, EU-Alert
ETWS requirements are defined by Japanese requlator, but not normatively referenced from 3GPP specifications 3GPP TS captures the 3GPP system requirements for ETWS CMAS is defined under FCC CFR 47 Part 10 Rules in the U.S. CMAS Standards developed by ATIS and TIA: J-STD-100, J-STD-101, ATIS , ATIS , ATIS , ATIS EU-Alert requirements are specified in ETSI ETS

11 CMAS architecture E-UTRAN Access specific broadcast procedures UTRAN
Public authority E-UTRAN Network Operator UTRAN Access specific broadcast procedures GERAN 11

12 CMAS Call Flow Example CMSP Gateway in the operator network receives the CMAS alert from the government entity The alert is passed to the operator’s cell broadcast centre (CBC) which identifies the cell site(s) to broadcast the alert The alert is broadcast using 3GPP PWS

13 Summary PWS was designed by 3GPP as a global solution for issuing public warnings over 3GPP mobile systems PWS is designed to allow extendable set of national and regional specific alerts while maintaining global uniqueness PWS is a service for alerting and updating the user of emergency situations in a timely, secure, and geographically selective manner PWS architecture provides interface towards public authorities who generate and authorize the warnings uses common PWS broadcast and message coding capabilities uses radio specific cell broadcast procedures in GSM, UMTS and LTE is extendable in future 3GPP enhancements


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