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Architecture of iMode. Matthew Caesar 4/3/02. What is iMode?. Goal: Easily enjoy Internet services on mobile phone Overlay on top of DoPa packet network Subscriber: New, advanced services on mobile device Operator: A way to attract new users and increase revenue
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Architecture of iMode Matthew Caesar 4/3/02
What is iMode? • Goal: Easily enjoy Internet services on mobile phone • Overlay on top of DoPa packet network • Subscriber: • New, advanced services on mobile device • Operator: • A way to attract new users and increase revenue • Users charged on per-packet basis (~0.22 cents/128byte) • Payment collection for third-party information providers
Statistics • iMode a huge success • Today, 80% of world’s wireless Internet users are in Japan (12.5% in Korea, 5% in Europe, 1% in USA) • 2% of world’s population is in Japan • Zero to 26M subscribers in 2.5 years, 50K more per day • 1,000 official sites; 30,000 voluntary sites • Early deployment • Packet network launch 1997 • iMode launch 1999 • -> Lots of time to experiment and learn
Goals • Stick to telephone • Enjoy Internet without bulky, slow PDA or PC • Easy to use • Users unaware of Internet • Adapt browser to mobile device • Leverage Internet technologies • IP, TCP, HTTP, SSL, Java • Media diversification • Allow third parties to provide information
Architecture Info. Provider HTTP/TCP/IP Leased Line Info. Provider Packet Network (PDC-P) iMode Server Info. Provider HTTP/TCP/IP PC Communication Network (PDC) Internet PSTN Groupware Server PC
Packet Network (PDC-P) iMode Server I-MAX M-PGW I-MAX M-PGW M-SCP I-MAX • BS: Base Station • PPM: Packet Processing Module • PGW: Packet Gateway Module • M-PGW: Mobile Message-Packet Gateway Module • M-SCP: Mobile Service Control Point • I-MAX: Interface-Mobile Access Exchanges PGW M-PGW IP PPM PPM Internet IP BS BS BS BS MS MS MS MS
iMode Server To PDC-P M-PGW SW I-MAX1 SW RT I-MAX1 To PDC-P • Functions: • Internet Access Proxy • Mail Storage • User Management • Information charging M-PGW U-MAX M-MAX C-MAX W-MAX N-MAX To PDC-P M-PGW I-MAX8 SW RT SW Customer Center Maintenance Terminal B-MAX D-MAX SW RT Sales Analytic Terminal SW RT Itemization Center ISP1 Business Remote Terminal Leased Line ISP2 RT SW F/W Leased Line RT SW F/W Leased Line IP RT SW F/W
Protocols • TLP • Improved efficiency in PDC-P network over TCP (uses fewer packets to save charges) • Higher data packet ratio • No 3-way handshake, control signals can piggyback data • ALP • Supports both pull (HTTP) and push style communication • Direct HTTP communication between mobile phone and iMode server • UITP (User Information Transfer Protocol) sends subscriber information from PDC-P network to iMode server • NWMP (Network Management Protocol) performs signaling • Start/end of packet communication • E.g. email delivery, push content notification iMode Server Telephony Function HTML Mail ALP (Application Layer Protocol) ALP (Application Layer Protocol) TCP TLP (Transport Layer Protocol) IP PDC PDC-P
Security • SSL (adopted March 2001) • End-to-end SSL(e-eSSL) with server-side authentication • Phones have pre-configured keys • Client-side authentication is future work • Non-repudiation is not yet possible • Can also do SSL just between IP and iMode server (s-sSSL) • PDC-P network doesn’t have to be trusted • Java • Can run applets from IP • Java Application Manager (JAM) prevents access to handset
Current and Future Services • Digital Music Distribution • Car Navigation System • Email • Internet/web access • E-Commerce • Video-calls • Streaming media • Java Games • Schedule Management • File sharing • BBS • Multi-party Conferencing • Workflow Management • Mobile TV • Interactive TV • Video distribution • Music Distribution • Mobile Banking Concert Ticket Booking Travel Service Credit Card Bill Inquiry Mobile Trading Karaoke Fortune-telling Dictionary search Restaurant guide Walking/driving/subway directions News Housing information Weather forecast Telephone directory Airline information Hotel Reservation Discount Tour Info Stock Information Cooking Recipes Club/Event Info Downloadable Characters Horse Racing Information Location Information Horoscope CAD Complex vector graphics Flash software Animated Mail Vending Machine Interface
Application Scenario: Railroad Facility Management System • Japanese railroad companies use PDAs • Display diagrams of wires, tracks, signals, communications • Collect data and workflow management • Consider using iMode phone instead • Disadvantages of PDA: • Too heavy, difficult to operate • Low bandwidth (wired) • No dynamic updates • Expensive • Disadvantates of iMode phone • Small display size • Spotty coverage (tunnels, near buildings) • Low bandwidth (wireless) • M. Kikuchi, Y. Yagi, “Use of iMode Cellular Phones for Facility Management System”
Hardware Demands • Low Power Ics • Most power consumed by power amp • New applications require more power • SSL, Multimedia, Java • Memory • 10x larger memory required • Non-volitile storage required for media downloading services • LCD • More colors, faster response speed => greater power drain • Battery • Currently 30% of unit total weight (large) • H. Yazaki et. al., “Overview of Advanced iMode Mobile Phones” • K. Enoki, “iMode: The Mobile Internet Service of the 21st Century”
Comparison with WAP/WML iMode • Wireless internet service (could be deployed over WAP) • Sites based on HTML (cHTML) • 60% of world’s wireless internet users • Usually used over packet switched connections • Services user-oriented, fun-oriented • Anyone can produce content, DoCoMo operates content menus WAP • Specification for presenting and interacting with information on wireless • Sites based on new WML • 39% of world’s wireless internet users • Usually used over circuit switched connections • Services business-oriented, work-oriented • Anyone can produce content, content menus
Recent News • iMode Launch in USA via ATT wireless • Expected to launch soon • Stripped down service • Currently being deployed in Europe by E-Plus • Already deployed in Germany
References • Web sites: • The iMode FAQ: http://www.eurotechnology.com/imode/faq-sec.html • http://www.acsac.org/2001/papers/61.pdf • Official iMode Site: http://www.nttdocomo.com/imode/top.html • “Special Issue on iMode Service”, NTT DoCoMo Technical Journal, Oct. 1999. • “Special Article on Advanced iMode Mobile Phones,” NTT DoCoMo Technical Journal, Jun 2001 • “Wired versus Wireless Security: The Internet, WAP and iMode for E-Commerce”, ACSAC 2001 • “iMode: The Mobile Internet Service of the 21st Century”, ISSCC 2001 • “Learning from iMode,” IEE Review, Nov. 2001