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Wireless Networks

Amit Jain and Petter KaralMedia Tech ClubSloan School of ManagementMay 2, 2000

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Mobile + Internet =

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The Mobile Internet

mCommerce

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The Mobile Internet

work anywhere

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The Mobile Internet

play anywhere

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The Mobile Internet

anytime

anytime

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MediaTech Wireless 101

Technical workshop

How wireless worksToday’s different

systemsThe future of

wireless technology

Business workshop

Markets and players

TrendsSuccess factors

Today

Today

May 9

May 9

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Technology enables marketing

Wireless technologies are very fancy, fun and intellectually exciting

Don’t fall into the tech trap

The business workshop is the “really” important part - this is preparation

WARN

ING

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Agenda

How does it work?

Today’s systems

Wireless technologies in the near future

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A wireless network

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Connects a mobile phone...

Mobiles send and receive radio signals to base stations (called BTS)

Each BTS has a service area

Several BTS are connected to a BSC over copper, fiber or microwave links

When a mobile moves from one service area to another, a handoff occurs

BSC directs the handoff, with or without the assistance of the mobile

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To the rest of the world!

BSCs are connected to Mobile Switching Center (MSC)

MSC connects mobile to other phones/devices in the world

MSC maintains subscriber database for Billing Roaming agreements Paging mobiles for incoming

calls

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Talking over the air

Bandwidth is limited (and expensive) FCC raised over $5 billion in PCS auction UK licenses recently auctioned for $35 billion Each operator has 5-10 MHz Each mobile call needs ~25KHz Frequency must be re-used

Wireless link unreliable Severe radio propagation losses Interference from other networks and users

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Air interface standards

Examples: FDMA, TDMA, CDMA Define how the phone talks to the network Determine how network solves the frequency

reuse, reliability, and voice quality problems Determine cost of a network and its capacity

Most phones are designed for one air interface and one frequency

Multi-mode phones work over multiple air interfaces but cost substantially more

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*DMA compared !

Consider a room with many people trying to have a conversation.

If they all speak at different frequencies, FDMA

If they take turns to speak, TDMA

If they all speak together but in different language, CDMA.

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Frequency Division Multiple Access (FDMA)

Spectrum is divided into channels

Each call takes one channel for the entire duration of a call

Geographical separation allows channels to be reused

Still used in US analog systems

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Spectrum

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Time Division Multiple Access (TDMA)

Channels are divided into time slots

Each user gets a channel and a time slot

Uses digital modulation to improve voice quality and capacity

GSM is the leading TDMA based standard

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Code Division Multiple Access (CDMA)

All users use the same wide band channel

Users are separated by encryption or codes

Encryption/decryption needs huge computational power

Provides dramatically higher capacity

Well suited for transmitting packets i.e. data

Used by military since 50s, commercialized by Qualcomm in 90s

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Agenda

How does it work?

Today’s systems

Wireless technologies in the near future

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End-to-end mobile phone standards

Each standard covers air interface, mobility manage-ment, switching, inter-connectivity and other issues

AMPS : Advanced Mobile Phone System Established 1983 by AT&T

GSM : Global System for Mobile communications Established 1990, Europe Ericsson, Nokia, Omnipoint, Pacific Bell, all European carriers

cdmaOne Established 1995 Qualcomm, Motorola, Lucent, Sprint PCS

Others (D-AMPS, TDMA, N-TDMA, TACS, DECT...)

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AMPS

Still used in AT&T and AirTouch Networks in the cellular band

FDMA based air interfacePoor voice qualityHandoffs are done without the

assistance of the mobile, unreliable

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Higher capacity (2X over AMPS) TDMA air interface instead of FDMA

Better voice quality Digital voice encoding/decoding

Excellent roaming One phone, many networks

SIM cards Painless phone upgrades

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Higher capacity (5X over GSM) CDMA air interface instead of FDMA

Superior voice quality Digital encoding/decoding

Smooth handoffsSimpler network design

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GSM is predominant

67%

13%

11%8%

Total worldwide subscribers: 490 million

Share of digital mobile subscriber market

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Agenda

How does it work?

Today’s systems

Wireless technologies in the near future

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The MobileInternet vision

Any application...…on any device…anytime…anywhere

“The Network is the Computer”

- Scott McNeally

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The third generation of wireless (3G) is coming

Value to user

Introduction

1G: Analog voice

2G: Digital voice+

3G: High-speed multimedia internet access

~1980 1990 2002

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3G adds functionality and more connectivity

Multimedia capable Pictures Music Video

Internet connectedPacket-switched

(144 to >2000kps)Location sensitive

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Access by many different devices and technologies

Access from different devices (“terminals”) at different timesPhone deviceCarPDA/palmtop computerDesktopFridge?

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Today’s phones evolveinto funky devices

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3G must overcomeseveral challenges

Standardization Tug-of-War over technical aspects of global

standards waged in many forumsMigration

Old customers, networks and frequencies can’t simply be discarded

Technology High-speed data devours batteries, heats

handsets and uses a lot of spectrum

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Standardization for 3G

Three coinciding technologies DS-CDMA (UTRA FDD) MC-CDMA UTRA TDD

“Harmonization” - maximizing compatibilityDoesn’t matter all that much

Most consumers aren’t global Multi-band/multi-mode phones can roam the

world anyway

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Several step-stones for3G migration

Circuit-switched internet access WAP (discussed later)

Upgrades to 2G (“2.5G”) GPRS: Upgrades GSM to PS at 50-115kps cdma2000: High-speed data over cdmaONE

Upgrades to 3G of current networks EDGE: Upgrades GSM/GPRS and

TDMA/AMPS to 3G, with data rates of 50-473kps

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Related technologies

Operating systems (OS) for terminalsShort-distance wireless networkingApplications and servicesSecurity systemsLocation specificityNew input/output technologies

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Operating systemsBattle to become the “Windows of Wireless”Players come in at different angles

EPOC (Symbian) - the OS for the PSION PDA Palm OS Pocket CE - was: Windows CE, Microsoft’s “all

gadgets” OS Phone.com - WAP browser “all you need”? Mobile Linux - no position now, but potential Java - might make underlying OS “irrelevant”

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Widely adopted standardCheap chip that communicates via

microwave radioEnables devices within 30’ to

network spontaneously (forming “Piconets”)

Speed: 1mps, allegedly bound for 10mps

Short-distance wireless networking:

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Many kinds ofapplications

“Hardcoded” functionalityInstalled software (possible today on

PDAs, Palmtops; not on cell phones)Wireless-enabled web sitesNetwork applications - run them on

distant servers using browser

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Example applications

E-mail = instant messagingArrival services

Device knows you and your position - offers relevant booking services for transportation, as well as for dining and entertainment

Web-based enterprise systems Store and retrieve files, look up information

and perform transactions from anywhere, anytime

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Security systemsenable transactions

Main focus: To enable secure transactions

Key technology: Public Key Encryption (PKI)

Many players race to define industry standard

Strong contender: Hardware-based systems (smart-cards; chips)

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Your service will be tailored by your location

Location tracking required by US law for 9-1-1 purposes (“e911”)

Several technologies Analysis of signals and handoffs GPS (not used in mobile devices yet) Bluetooth (not sufficient for e911, though)

Current systems are not very precise; will improve

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New ways to operate your wireless device

New input technologiesPalm Grafitti (has been around for a while)Keyboard variantsIntegrated cameraSpeech recognition

New output technologiesNew screensScreen specs - glasses with display

Crazy stuff coming: Direct retinal projection, implants, AI, neural interfaces

HYPE?

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And the killer app is...

Voice!

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Wireless Application Protocol, W@P

Emerging standard for presentation and delivery of data on wireless phones

Designed to work within the constraints of existing wireless and phone technology

Standard initiated by Unwired Planet, now Phone.com, with the support of Nokia, Ericsson and Motorola.

Today WAP Forum has 100+ members

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W@P architecture

Phone

MicroBrowser- WML- WMLScript- WTAI

WAP Gateway

- Encode Reqs- Decode Reqs- DNS- Proxy Server- Optimization

CGI

ContentHTTPServer

WMLDecks

Java/ASP

Web Server

WAP ProtocolsWSP/WTP/WDP

StandardHTTP 1.1

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Why do we need W@P ?

Wireless devices are not PCs Devices are small Limited CPU, RAM Support Voice, Telephony

Wireless channel is not copper or fiber Unreliable Low Bandwidth High Latency

Standardization is essential for developing applications

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W@P protocols

Independent of wireless standards

Security

Micro-browser,WML, WMLScript,WTAI

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WML: Decks and cards

1> Pizza2> Chinese3> Indian

1> Pepperoni2> Meat Lovers3> Veggie

Cost $9Buy?

Cost: $8Buy?

Cost: $11 Buy?

1> Tandoori2> Naan Bread3> Dosa

1> Kung Pao2> Schezuan3> Fried Rice- Web servers

always send “decks”

- Decks contain “cards”

- Each card is ONE user interaction

- Decks maintain state information

One“deck”

One “card”

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WAP Gateway

Translates WAP requests to HTTP and TCP/IP

Encodes and decodes content to reduce size and number of over-the-air packets

Off-loads phone from computation intensive tasks

Maintains cookies / user informationCaches commonly accessed information

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Cellular Digital Packet Data (CDPD)

Technology currently used by Palm, RIMM Palm.net, GoAmerica (NASDAQ:GOAM) resells

service from ATT, Bell Atlantic, AmeritechUses a digital overlay of existing networkData sent using TCP/IPMaximum data rate = 19.2 kbpsBilled by the byte

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CDPD and WAP compared

CDPD Network Overlay

Required Uses TCP/IP Dedicated devices

like Palm, wireless modem

Packed-switched Charge by the byte

W@P Works on existing

network Own network

protocol Software upgrade

of phone Circuit and Packet Charge by the

minute

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i-mode

Wireless service launched in spring 1999 in Japan by NTT DoCoMo

“3G light”Web content based on subset of HTMLPacket-switched, multimedia enabledLow bandwidth (9.6kps), but improved by

compression and will move to 14.2kps

Extremely successful:6 .1M customers; growing at 200,000/weekThousands of services provided

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Q&A

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Conclusion

The main 2G standards are GSM and CDMA 3G standards are coming that will enable

consumer multimedia internet from any device

Many new dimensions to internet services (context-specific, on-the-spot, continuous)

Technological feasibility drives the evolution of the Mobile Internet (for now)

Be skeptical to hype

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Resources

3G acronym expander: www.nokia.com/3g/acronyms/0,7076,,00.html Mobile commerce glossary: maffin.net/mobilecommerce/glossary.htm Great news compilation on wireless: www.mobic.com Ericsson background papers (pretty technical, but great):

www.ericsson.se/review/issues.taf Bluetooth homepage: www.bluetooth.com WAP Forum: www.wapforum.org Equipment providers’ homepages:

www.motorola.com www.ericsson.com www.nokia.com

Web site on wireless devices: www.allnetdevices.com Consultancy gives “teasers” on its reports: www.ovum.com