JFS 10/11/00JFS May, 2001

Wireless Overview

John Skeffington, Sun Microsystems

National Wireless Engineering ConferenceOctober 31, 2000

Cellular

JFS 10/11/00JFS May, 2001

Agenda

• Historical Perspective • Building a Cellular System• Current Landscape• Future Landscape

JFS 10/11/00JFS May, 2001

Historical Perspective (US)

• Evolved from Two-way Radio Systems• Mobile Phone System (MTS)

– Operator Interaction Required– 15 - 25 Simultaneous Users on System

• Improved Mobile Phone System (IMTS)– Incorporated Direct Dial – Still in Service until Early 1990’s

• Advanced Mobile Phone Service (AMPS)– 1st Commercial Phone Call Placed in 1983

JFS 10/11/00JFS May, 2001

Definitions

• Wireless - Large coverage area, high mobility (pedestrian and automotive) usage.

• Cellular - A communications system where a small number of radio frequencies are carefully managed and re-used in a geographic area. – Full duplex, two frequencies used for each conversation

• PCS - Personal Communications System - A spectrum of frequencies allocated by the FCC for newer cellular type technologies.

JFS 10/11/00JFS May, 2001

Agenda

• Historical Perspective • Building a Cellular System• Current Landscape• Future Landscape

JFS 10/11/00JFS May, 2001

Pre Cellular ServicePre-Cellular Scenario - Metropolitan area using seven channels (14 frequencies): seven simultaneous calls

JFS 10/11/00JFS May, 2001

Basic Components

• Mobile Switch• Central Switching Office Building• Base Stations• Leased locations for Base Stations• Connections to Landline• Antennas, Cable, Towers, etc.• Mobile Phones• Customers

JFS 10/11/00JFS May, 2001

Basic Analog Cellular System

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

SystemSubscriber

Data Base

PSTN

BillingSystem

JFS 10/11/00JFS May, 2001

Assumptions for “My Mobile”

• Mobile Switching Center in place• Base Station (BTS) equipment cost $250,000• Base Station Construction cost $200,000• BTS rental $1000 per month• One T1 line required per BTS, $1200 per month• Subscriber usage is 50 minutes per month• 5% of subscribers use system at any given time• BTS upgrade is $100,000 • Very simplistic financial estimating

JFS 10/11/00JFS May, 2001

My Mobile Service

3 BTS $3600/mon3 T1 $3000/mon21 simultaneous calls420 subscribers$0.31 per minute

3 BTS $ 750,000

BTS const $ 600,000

Total Capital $1,350,000

Three Cell System

JFS 10/11/00JFS May, 2001

Handoffs• Handoff: Major enabling technology that creates

mobile communications, transfer of call from one cell to another– First generation handoffs (AMPS)

– MSC initiated, mobile had “passive” role– MSC would query neighboring cells to determine when to

handoff based on received power getting lower.– “Intelligence” of handoffs contained to MSC

– Hard Handoff: “break before make” connection – Second generation handoff

– Mobile initiated, mobile has active role– Database assisted

– Soft Handoff: “make before break” connection

JFS 10/11/00JFS May, 2001

Basic Hard Handoff

A

B

C

• Caller is active in cell A

• Caller is driving on “blue” road

• System detects lower signal level in cell A as caller moves to edge

• System checks other cells to determine which has stronger signal

• Cell B is determined to be stronger signal

• System directs mobile to tune to Cell B frequency

JFS 10/11/00JFS May, 2001

Basic Hard Handoff

A

B

C

• Mobile tunes to cell B while still on call

• Call is now established in cell B

• System detects lower signal level in cell B as caller moves to edge

• System checks other cells to determine which has stronger signal

• Cell C is determined to be stronger signal

• System directs mobile to tune to Cell C frequency

JFS 10/11/00JFS May, 2001

Basic Hard Handoff

A

B

C

• Mobile tunes to cell C while still on call

• Call is now established in cell C

• System detects lower signal level in cell C as caller moves to edge

• System checks other cells to determine which has stronger signal

• Cell A is determined to be stronger signal

• System directs mobile to tune to Cell A frequency

JFS 10/11/00JFS May, 2001

My Mobile Service

1 MSC8 BTS $9600/mon8 T1 $8000/mon56 simultaneous calls1120 subscribers$0.31 per minute

5 BTS $1,250,000BTS const $1,000,000Total Capital $2,250,000

Eight Cell System

JFS 10/11/00JFS May, 2001

Definitions• Down Link, Forward Link - Radio connection from base

station to mobile• Up Link, Reverse Link - Radio connection from mobile

to base station• Channel: A physical (or logical) radio frequency(s)

– Traffic (voice) channel - A channel dedicated to voice usage– Control (overhead) channel - A channel dedicated to control

functions– Access Channel - Channel used for mobile to gain access to system (reverse

link)– Paging Channel - Channel used for messaging from system to mobiles

(forward link)

JFS 10/11/00JFS May, 2001

Forward / Reverse Links

Up Link

Down Link

Up Link

Down Link

0.6 watt portable3 watt portable

JFS 10/11/00JFS May, 2001

Power Control●System works best when all mobiles appear to be same power at base station●Mobility of mobiles requires power control to be dynamic●Base station tells mobiles whether to power up or down●Revisions made to original AMPS specs to allow additional (lower) power levels●CDMA power control happens every 20 msec

JFS 10/11/00JFS May, 2001

Why is Power Control Needed?●Many Mobiles, many Distances●Power Level Inversely Proportional to Square of Distance

● Mobile at One Mile = One Watt● Same Mobile at Two Miles = 1/4 Watt● Same Mobile at Three Miles = 1/9 Watt

1 2 3 4 5 6 7 8 9 100

0.5

1

1.5

2

2.5

3

3.5

4

4.5

distance

power

JFS 10/11/00JFS May, 2001

Where do I Place Sites?●Site Location Factors●Link Budget

● Method of estimating power levels anywhere within coverage

●Technical● Terrain and Clutter● Equally spaced “cell centers”

●Business● Lease cost● Acquisition and Construction cost

JFS 10/11/00JFS May, 2001

System Design Tools• Tools predict propagation

of radio signal based on link budget

• Creates many different output formats

Ideal Cell Locations

Predicted Signal Levels

JFS 10/11/00JFS May, 2001

System Manangement

JFS 10/11/00JFS May, 2001

28 Cell Cellular System1 MSC28 BTS $33600/mon28 T1 $28000/mon196 simultaneous calls3920 subscribers$0.31 per minute

20 BTS $5,000,000BTS const $4,000,000Total Capital $9,000,000

JFS 10/11/00JFS May, 2001

1

2

3

4

5

6

7 1

2

3

5

7

2

37

4

1

2

37

1

4

56

7

7

5

Frequency Re-useMetropolitan area using seven channels: 28 simultaneous calls. Seven cell re-use pattern, same frequency never closer than two cell radii.

6

Numbers represent frequency being usedHexagons represent cell coverage areasShading represents frequency grouping

JFS 10/11/00JFS May, 2001

High Usage Cells

1 MSC28 BTS $33600/mon28 T1 $28000/mon196 simultaneous calls3920 subscribers$0.31 per minute

High Usage Cells (hot spot) develops based on statistics from system

JFS 10/11/00JFS May, 2001

Increasing Capacity

●Omni-directional cell transmit equal power in all directions●Cells can be split into sectors using directional antennas●Requires additional BTS equipment●Very similar to multiple cells in same location●Careful frequency planning required●Most common is three sector, but six sectors have been implemented in many cities●Sectorizing and adding “voice channels” very profitable to equipment provider

Omni-directional cell

Sectorized cell

JFS 10/11/00JFS May, 2001

Capacity Increased1 MSC28 BTS $33600/mon34 T1 $34000/mon238 simultaneous calls4760 subscribers$0.28 per minute

3 BTS upgrades $300,000

JFS 10/11/00JFS May, 2001

System Monitoring

●28 base stations in service 24 x 7●System reports statistics every 10 minutes

● 40 items each base station ● 6,720 per hour, 161,280 per day

● Each T1 status reported● 168 per hour, 4,032 per day

●Lots of data to look at !

JFS 10/11/00JFS May, 2001

Additional Hot Spot1 MSC28 BTS $33600/mon34 T1 $34000/mon238 simultaneous calls4760 subscribers$0.28 per minute

JFS 10/11/00JFS May, 2001

More Capacity Needed1 MSC28 BTS $33600/mon40 T1 $40000/mon280 simultaneous calls5600 subscribers$0.26 per minute

3 BTS upgrades $300,000

JFS 10/11/00JFS May, 2001

Additional Capacity Added

1 MSC28 BTS $33,600/mon49 T1 $49,000/mon343 simultaneous calls6860 subscribers$0.24 per minute

3 BTS upgrades $300,000

JFS 10/11/00JFS May, 2001

Entire System Sectorized1 MSC28 BTS $33,600/mon93T1 $93,000/mon651 simultaneous calls13020 subscribers$0.19 per minute

22 BTS upgrades $2,200,000

JFS 10/11/00JFS May, 2001

Analog Cellular System

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiverSystem

Subscriber

Data Base

PSTN

BillingSystem

Voice MailSystem

Customer CareSystem

ProvisioningSystem

Connection to other networks

JFS 10/11/00JFS May, 2001

Network Sizing

MobileSwitching

CenterBase

TransceiverSystem

BaseTransceiver

System

BaseTransceiverSystem

Subscriber

Data Base

PSTN

BillingSystem

Voice MailSystem

Customer CareSystem

ProvisioningSystem

Connection to other networks

• Public Switched Telephone Network is at Center of Mobile Network

• Interconnect Between devices needs to be sized properly

JFS 10/11/00JFS May, 2001

Network Sizing

●Most networks sized for 2% blocking●Unit of measure for telco sizing

● Erlang● Equivalent to one phone call for 60 minutes● Used to size a path through the network● One Erlang:

– 1 - 1 hour call– 2 - 30 minute calls– 4 - 15 minute calls– 60 - 1 minute calls

JFS 10/11/00JFS May, 2001

First Generation Cellular●Advanced Mobile Phone System (AMPS)

● American Standard, 824 MHz – 894 MHz● Initially 666, Later Expanded to 832 Channels

● Split Between Two Carriers● A Carrier (non- wireline carrier)● B Carrier (wireline provider)

● 42 Control Channels (21 for each carrier)● First Commercial Cellular Phone Call Made in 1983● Designed as "Higher Power" (3 watt) Car Based System● Proprietary System for Infrastructure Vendors

JFS 10/11/00JFS May, 2001

Other First Generation

●Nine Incompatible Standards used in Europe ● Total Access Communication System (TACS) – UK● Nordic Mobile Telephone (NMT)

●Japanese Total Area Cellular System JTACS●Proprietary System for Infrastructure Vendors

JFS 10/11/00JFS May, 2001

Capacity Increases in 1 G Networks●Increase Spectrum

●Cell Splitting (requires careful frequency planning)

● Three Sector● Six Sector● Add Additional Cells

●Move to Digital Standard● Significant Improvement with similar Infrastructure

Investment

JFS 10/11/00JFS May, 2001

Generic Digital System

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

System

Subscriber

Data Base

PSTN

Internet

IWF

Base Station

Controller

Voice MailSystem

Customer CareSystem

ProvisioningSystem

Connection to other networks

JFS 10/11/00JFS May, 2001

Second Generation Systems●GSM – Global System for Mobile

● Channelized, 6 Time Slots / Channel● Time Division Multiple Access (TDMA) Based ● Most Widely Deployed, Most Predicted Growth● Common Digital Standard Across Europe, Africa, Middle East, US● SIM cards widely used● Defined Interfaces Between Infrastructure Elements

● Multiple Vendors Used in Same Network● First Commercial Service in 1991● Frequency Planning Crucial● Major Vendors: Ericcson, Nokia, Nortel, Motorola, Lucent

JFS 10/11/00JFS May, 2001

Second Generation Systems

●Time Division Multiple Access (TDMA)● Channelized, 3 Time Slots/Channel ● Primarily Deployed in US

● AT&T Wireless (Dual Band, Dual Mode Phones, IS-154)● SBC (Cellular One in Chicago, IS-54)● Some Markets Will be Transitioned to TDMA from CDMA due to mergers

● Frequency Planning Crucial● First Commercial Service in 1990● Typically One Infrastructure Vendor per Market● Major Vendors: Ericsson, Lucent

JFS 10/11/00JFS May, 2001

Second Generation Systems

●Code Division Multiple Access (CDMA)● Spread Spectrum Coded Transmission, Non Channelized● One Frequency for Entire System● Primarily Used in US, Canada, Australia, Korea and parts of

China● SprintPCS, Verizon, PrimeCo

● Typically One Infrastructure Vendor per Market (not per Carrier)

● Complex Power Control● First Commercial Service in Late 1995● Major Vendors: Nortel, Lucent, Motorola, Ericsson, Nokia

JFS 10/11/00JFS May, 2001

Mobile Call Origination FlowRegistration

Control and System Parameters

Dialed Digits

Traffic Channel Information

Access Request

Access Confirmation

Call Setup Information

Call Setup Information

Call Termination

Release Resources

Mobile Communication

System

Mobile Communication

s Device

Phone Call

JFS 10/11/00JFS May, 2001

Mobile Call Origination

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

SystemSubscriber

Data Base

PSTN

Mobile to Land Call Flow Example

Mobile User Initiates Call

JFS 10/11/00JFS May, 2001

Mobile Call Origination

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

SystemSubscriber

Data Base

PSTN

Mobile to Land Call Flow Example

JFS 10/11/00JFS May, 2001

Mobile Call Origination

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

SystemSubscriber

Data Base

PSTN

Mobile to Land Call Flow Example

Validate Subscriber

JFS 10/11/00JFS May, 2001

Mobile Call Origination

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

SystemSubscriber

Data Base

PSTN

Mobile to Land Call Flow Example

Valid Subscriber

JFS 10/11/00JFS May, 2001

Mobile Call Origination

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

SystemSubscriber

Data Base

PSTN

Mobile to Land Call Flow Example

Phone Rings

JFS 10/11/00JFS May, 2001

Mobile Call Origination

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

SystemSubscriber

Data Base

PSTN

Mobile to Land Call Flow Example

Phone Answered

JFS 10/11/00JFS May, 2001

Mobile Call Origination

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

SystemSubscriber

Data Base

PSTN

Mobile to Land Call Flow Example

Call Established

JFS 10/11/00JFS May, 2001

Mobile Call Termination FlowRegistration

Control and System Parameters

Page Response

Page for Mobile

Call Setup Information

Call Setup Information

Call Termination

Release Resources

Mobile Communication

System

Phone Call

Mobile Communication

s Device

JFS 10/11/00JFS May, 2001

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

SystemSubscriber

Data Base

PSTN

Mobile Call TerminationLand to Mobile Call

Flow Example

Land Line User Initiates Call

JFS 10/11/00JFS May, 2001

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

SystemSubscriber

Data Base

PSTN

Mobile Call TerminationLand to Mobile Call

Flow Example

Validate Subscriber

JFS 10/11/00JFS May, 2001

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

SystemSubscriber

Data Base

PSTN

Mobile Call TerminationLand to Mobile Call

Flow Example

Valid Subscriber

JFS 10/11/00JFS May, 2001

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

SystemSubscriber

Data Base

PSTN

Mobile Call TerminationLand to Mobile Call

Flow Example

Page Mobile

JFS 10/11/00JFS May, 2001

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

SystemSubscriber

Data Base

PSTN

Mobile Call TerminationLand to Mobile Call

Flow Example

Page Response

JFS 10/11/00JFS May, 2001

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

SystemSubscriber

Data Base

PSTN

Mobile Call TerminationLand to Mobile Call

Flow Example

Page Response

Update SubscriberDatabase

JFS 10/11/00JFS May, 2001

MobileSwitching

Center

BaseTransceiver

System

BaseTransceiver

System

BaseTransceiver

SystemSubscriber

Data Base

PSTN

Mobile Call TerminationLand to Mobile Call

Flow Example

Page ResponseCall Established

JFS 10/11/00JFS May, 2001

Spectrum ComparisonAMPS

TDMA

GSM

CDMA

no time slots

3 time slots

8 time slots (6 voice, 2 control)

180 kHz

180 kHz

200 kHz

1.23 MHz

30 kHz

30 kHz

JFS 10/11/00JFS May, 2001

Comparison of Current Systems

AMPS GSM TDMA CDMA

Physical Channelsper Carrier 1 8 3 Variable

Channel Spacing(kHz) 30 200 30 1,230

Cellular Efficiency(conversations

/cell/MHz)2.3 5.0 – 6.6 7.0 12.1 – 45.1

CapacityCompared to

AMPS- 2.1 – 2.8 3 5.2 – 19.6

CapacityCompared to GSM - - 1 - 1.4 1.8 – 6.8

CapacityCompared to

TDMA- - - 1.7 – 6.4

Reference David J. Goodman, Wireless Personal Communications Systems, 1997 Addison Wesley Longman, Inc.

JFS 10/11/00JFS May, 2001

Agenda

• Historical Perspective

• Cellular Overview

• Current Landscape

• Future Landscape

JFS 10/11/00JFS May, 2001

Chicago Wireless Market

• Seven Carriers now in service– Cingular - TDMA (AMPS & IS-54)– Verizon - CDMA(AMPS, IS-95A/B, Jstd-8)– Nextel - TDMA based – PrimeCo - CDMA(Jstd-8)– Sprint PCS - CDMA (Jstd-8)– AT&T Wireless - TDMA(IS-136)– VoiceStream -GSM

JFS 10/11/00JFS May, 2001

Issues Facing Today’s Carriers• Network Sizing

– Coverage vs. Capacity– Quality of Service

• Hot Spots– Concentrated areas of usage– Special Events, Sporting Events, Trade Shows – Emergency Requirements

• E911

JFS 10/11/00JFS May, 2001

Network Sizing (14.4 kbps Terminals)

MobileSwitching

Center

BaseTransceiver

SystemBase

TransceiverSystem

BaseTransceiver

System

Subscriber

Data Base

PSTN

Internet

IWF

Base Station

Controller

2-3 Voice Channels per DS0

(64/3=21DS0)

64 Voice Channels

One T1 per 64Channel Base

Station

14.4 kbps

JFS 10/11/00JFS May, 2001

Current Situation

• Short Message Service (SMS)– Currently Deployed Across All Standards – 180 - 240 Characters per Message

• Wireless Internet Access– Wireless Application Protocol (WAP)– In Service now– Designed for Low Bandwidth– Compatibility Problems

JFS 10/11/00JFS May, 2001

Agenda

• Historical Perspective

• Cellular Overview

• Current Landscape

• Future Landscape

JFS 10/11/00JFS May, 2001

JFS 10/11/00JFS May, 2001

3G Challenges• Network Capacity

– Current Networks Sized to Provide 9.6 - 14.4 kbps– Future Networks to Provide 1+ Mbps– Capacity Planning (Where will it be needed?)– Ubiquitous Coverage (in-building, in-residence)– Cell Site Development Costs (alternatives to traditional cells?)

• Is 3G Viable - Auction Costs• What is 3G?

– Current Standards Define Technical Aspects– Is There a “Killer App”?

– Video (one and two way)?– Instant Messaging?

JFS 10/11/00JFS May, 2001

Evolving Wireless Standards

2G(up to 14.4 kbps)

2G+(up to 384 kbps)

3G(up to 2 mbps)

GSM

TDMA

CDMA

GPRS EDGE W-CDMA

IS-136+(64 kbps)

IS-95B(64 kbps)

IS-136HS

CDMA-2000

?

No Clear Winner - Yet!

1X-EV

JFS 10/11/00JFS May, 2001

A

Basic Soft/Softer Handoff

B

C

• Caller is driving on “blue” road• Caller is active in cell A sector 1

and cell B sector 3• Phone is constantly checking for

neighbor cells• Phone communicates with network

and adds sectors as they exceed power threshold

• Phone detects lower signal level in cell A S1 as caller moves to edge

• Cell A S1 is dropped from call• Cell B S2 is added to call

12

3

12

3

12

3

B

C

JFS 10/11/00JFS May, 2001

Basic Soft/Softer Handoff

C

• Caller is active in cell B sector 3 and cell B sector 2

• Phone is constantly checking for neighbor cells

• Phone detects cell C S1 as exceeding threshold, adds to call

• Phone detects lower signal level in cell B S3 as caller moves to edge

• Cell B S3 is dropped from call

12

3

12

3

12

3

A

B

C

JFS 10/11/00JFS May, 2001

Basic Soft/Softer Handoff

C

12

3

12

3

12

3

A

B

C

• Caller is active in cell B sector 2 and cell C sector 1

• Phone is constantly checking for neighbor cells

• Phone detects cell C sector 2 as exceeding threshold, adds to call

• Phone detects lower signal level in cell B sector 2 as caller moves to edge, cell B sector 3 is dropped from call

• Phone detects cell C sector 3 as exceeding threshold, adds to call

JFS 10/11/00JFS May, 2001

B

C

• Caller is active in cell C sectors 1, 2 and 3 - softer handoff

• Phone is constantly checking for neighbor cells

• Phone detects lower signal level in cell C sector 1 as caller moves to edge, cell C sector 1 is dropped from call

• Phone detects cell A sector 2 as exceeding threshold, adds to call

• Phone detects lower signal level in cell C sector 2,cell C sector 2 is dropped from call

Basic Soft/Softer Handoff

12

3

12

3

12

3

A

B

C

JFS 10/11/00JFS May, 2001

B

C

12

3

12

3

12

3

A

B

C

• Caller is active in cell C sector 3 and cell A sector 2

• Phone is constantly checking for neighbor cells

• Phone detects lower signal level in cell C sector 3 as caller moves to edge, cell C sector 3 is dropped from call

• Phone detects cell A sector 3 as exceeding threshold, adds to call

• Phone detects cell A sector 1 as exceeding threshold, adds to call

Basic Soft/Softer Handoff

JFS 10/11/00JFS May, 2001

B

C

12

3

12

3

12

3

A

B

C

• Caller is active in cell A sectors 1, 2 and 3 - softer handoff

• Phone is constantly checking for neighbor cells

• Phone detects lower signal level in cell A sector 2 as caller moves to edge, cell A sector 2 is dropped from call

Basic Soft/Softer Handoff

JFS 10/11/00JFS May, 2001

B

C

12

3

12

3

12

3

A

B

C

Basic Soft/Softer Handoff• Caller is active in cell A sectors 1

and 3 - softer handoff• Phone is constantly checking for

neighbor cell