Communications Inc
Public Emergency Alerts Over Cellular Phones
…The Challenges
Gyles Panther6 November 2003
Basic Alerts, Requirements
•Primary Notification (Alert)
•Instruction / Direction
•Calm and Inform
•Interactive Management
•Situation Analysis
Basic Alerts, Suitability
•Primary Notification (Alert)
•Instruction / Direction
•Calm and Inform
•People Management
•Situation Analysis
4
The Issues
• What constitutes Wireless
• Addressing Geographical Regions
• Network Issues (Carrier)
• Alerting Issues (Alertee)
• HandSet Issues (Phone)
• Implementation
5
Wireless Networks
• Cellular- GSM / TDMA / CDMA / IDEN
• Paging- One Way (POCSAG / FLEX)- Two Way (REFLEX / Data Networks)
• Data Networks- Mobitex / Ardis
• New cellular data capabilites- GPRS, 1xRTT
• Chosen Focus is Cellular
6
Short History of Cellular (3)
GPRS(170/60)*
(kb/s)
EDGE(384/144)*
(kb/s)
IS-136(TDMA)
North America
AMPSPrimarily
North America
GSMTDMAEurope
IS-95A(CDMA)
North America
IS-95B(CDMA)1xRTT
(144/60)*kb/s)
CDMA2000(CDMA)
1x/3xRTT(2Mb/144)*
kb/s)
W-CDMA(UMPTS)
(2000/144)*Mb/s)
1stGeneration
2ndGeneration
"2.5"Generation
3rdGeneration
"*" indicates Maximum/usable data rates
"IMT2000"
7
Normal (Voice) communications
• Network : locates handset by registration
• Control channel sets up comms
• Single phone Address i.e. One to One
• Cannot address One to Many
• No intrinsic mapping of cells to location
• Cells variable in size
8
Alert Transmissions
• Address ALL, i.e. Broadcast
• Registration irrelevant
• Geographical Address
• Alert Message Transmitted Digitally
• Message Content :- Displayed Text ( Language? )- Spoken ( Language?)
- Displayed ( Video +Speech, language? )
9
Data Over Wireless
• GSMGPRS…Packet data service 170kb/s raw; 40kb/s Usable ? EDGE…Enhanced GSM packet data 384kb/s raw; 60kb/s Usable?UMTS…3G Packet data service: 2Mb/s raw; 144kb/s Usable?
• CDMA1xRTT…Basic CDMA packet: 144kb/s raw; 60kb/s Usable?3xRTT…Enhanced CDMA packet, 2Mb/s raw; 144kb/s Usable?
• IDEN(?)
10
Existing Message Service
• e.g. SMS- Implemented by all carriers- Interoperable between carriers- Text Messages- Approximately 160 Character limitation
• EMS, MMS- Large data files- spooled voice- photographic Picture quality (needs display!)
• but….– All are Point to Point
11
GSM- Cell Broadcast
• Cell Specific BroadcastsPoint to MultipointShort messages, limited to 15 * 93 Characters (SMS-CB)Up to 64k CB “Channels”
• Optional ETSI Standard (1993)Software upgrade to GSM networkNot widely implementedLimited / no commercial payback.
• “Cell Broadcast Forum”Standardized handset requirementsUser Opt IN-OUT service selectionSMS-CB can trigger data “pull” ( via WAP )
12
Geographic Addressability
• Return path for 2-Way devices inherentlyrequires network location
• Cellular handsets continuously located through“registration” process
• Supposition of network geography on networklocation
• Geographic resolution depends on cell size,likely poor
13
Cell Broadcast – Limitations
• Cell Resolution is variable, – Network to network, – Place to Place
Roads
WantedCoverage
Region
Cell CoverageCarrier 'A'
Cell CoverageCarrier 'B'
Populated Region(Village)
FictitiousExample
14
Selective Area Reception
• Assuming………- A broadcast capability, regional or wide area- A population of network assisted GPS handsets…
• A Broadcast alert message with…. - “Network assist” GPS data- “Geographic Address” (targeted area)- Emergency alert Message- Enunciation control data- Plus control fields…
• Phones located in Geographic address respond…
15
Handset Function
• Special Alert- Display Standardized Message
- Streaming Audio File
• Probably amenable to commerce
• Cellular networks now data “pipes”
• Alert / Handset function
- Through Network definitions (eg CAB) ?
- Through Handset Software ?
16
Limitations and Liabilities
• Some Handsets will miss alerts:- Poor local coverage- Handset in use
• Handset use while driving banned some places• Warned user might consult display while driving
- Injury may result- Who owns legal liability?
• Much preferred to send voiced message- text to voice, or- Streaming audio file
17
A CAS System
• A CAS Server application- Highly reliable, Redundant architecture
- Authentication on Clients, direct users
• Message Gateway to each carrier
• Client population- Generator sites (Police, EMO, Environmental Agencies)
- GUI / GIS capability
- Overlay of Sensitive Sites
- Authentication of Users (generators)
18
A Cellular Alert System
Internet
Carrier 'A'
CAS ApplicationServer
Location 2
CAS ClientWeather (eg)
CAS ClientPolice, location 'a'
PSTN
Carrier 'A' Gateway
Carrier 'C'Gateway
Tx Tx
Cell Site
Data
Cell Site
Tx Tx
Data
Cell Site
Tx Tx
Data
Firewall&
Server
TrunckedRadio
PSTN
CASClientEnvironment
Carrier 'B'Gateway
Firewall&
Server
ReliableFrameRelay
CAS ApplicationServer
Location 1
Carrier 'B'
Carrier 'C'
ReliableInternet
Connectios
Distributed EmergencyAlert Contributors
EmergencyAlert Servers
19
Implementation
• Cell Broadcast Alerts- Now available GSM, Coming for CDMA- less than Ideal system could be built- Limited system, Patented
• Selective Area Reception- New Message Types- Handset software required- Better System, no patents
• Funding- Commercial Applications ?- Subsidies ?
20
Implementation
• Neither Do-able on Present Networks• CAB requires:
- CAB Network Implementation (Expensive?)- Public take-up of CAB capable phones- Network development (Geo overlay on Network Topology)
• SAR requires:- Extensive lobbying of specifying entities- New system message types (broadcast)- New generation of handsets/handset software
• Implementation must be International
21
Implementation
• Government -Industry group to define- Method of selective area access- Broadcast Message spec- CSAAC network requirements
• CAS system Design- Server system and Application S/W- Client Application Software
• CAS administrative functions- System management, Training, public awareness,
22
Challenges (1)
• 5 year horizon may require mandate
• Formation of common intent
• Complex service behaviour– Through Handset Software?– Through Network Standards?
• Agree on CAS method– Cell location– Selective Area Reception (GPS)
• Commercial Applications– Traffic, Geo-referenced Advertising
23
Thank You
Gyles Panther
Wi-Sys Communications Inc.
308 Legget Drive,
Ottawa, Ontario
K2K 1Y6
www.wi-sys.com
Communications Inc