TDMA Tutorial

Outline of Presentation

• Evolution of Technology– AMPS to TDMA

• The TDMA Digital Control Channel– Features and capabilities– Technical description

• Services and design examples

TDMA Standards Overview

• EIA 553– Analog AMPS-based technology platform

• IS-54B– Introduces a TDMA digital traffic channel

and a new feature set• authentication, calling number ID, message

waiting indicator, and voice privacy.

TDMA Standards Overview - cont.

• TDMA– Backwards compatible to IS-54B and EIA 553. Includes a digital

control channel and advanced features.

• TDMA Rev A– Upbanded IS-136 for seamless cellular service between 800 MHz and

1900 MHz frequency bands, over the air activation and programming services developed.

• TDMA Rev B– Introduces a range of new features (broadcast SMS, packet data etc.)

TDMA Standards Evolution

1988 1990 1992 1994 1996 1998

Capacity

Services

Quality

CoverageCost

TDMA Standards Process Begins

IS-54 Adopted by TIA/CTIA

TDMA in Commercial Service

TDMA Rev. 0

TDMA A plusEFRC

TDMA B

TDMA Traffic Channel Structure

• Modulation– /4 DQPSK - differential quadrature phase shift keying.

– Across air bit rate = 48.6 Kbps.

• Frame Structure– TDMA frame = 40mS.– Six 6.67 ms slots per frame, two slots used for full rate voice.

TDMA Slot Format

Sync SACCH Data CDVCC Data RSVD

TDMA Frame

40 ms

TDMA Speech Coding

• Speech and channel coding are important factors in good voice quality. Other factors include:

– System planning (handoff, reuse, coverage, etc.)– Handset design– Echo suppression, audio balancing, …

• Two speech codecs defined for TDMA– VSELP - Vector Sum Excited Linear Predictive – ACELP - Algebraic Code Excited Linear Predictive

• VSELP– Originally defined for IS-54B - 80s Technology

• ACELP– Newly defined for TDMA - 90s Technology - “state of the art”– Offers wireline voice quality in clean conditions

ACELP Channel Coding

Class-2 bits

Class-1 bits96

7

208

52

260260216

Coded Class-1 bits

5 Tail bits

7-bit CRCComputation

Rate 1/2 Convolutional Coding

48 Most Perceptually Significant Bits

Sp

ee

ch C

od

er

(AC

EL

P)

Pu

nct

urin

g

Vo

ice

Cip

he

r

2-s

lot

inte

rlea

ver

codec 7.4kbps

codec + channel coding = 7.4kbps + 5.6kbps = 13kbps

40 msec

speech frames x and y

speech frames y and z

TDMA Voice Quality

EFRC vs. VSELP

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

Cle

an

17 d

B 5

mph

17 d

B 3

0 m

ph

17 d

B 6

0 m

ph

15 d

B 5

mph

15 d

B 3

0 m

ph

15 d

B 6

0 m

ph

13 d

B 5

mph

13 d

B 3

0 m

ph

13 d

B 6

0 m

ph

Test Condition

MO

S EFRC

VSELP

Mobile Assisted Handoff (MAHO)

• System instructs mobile to measure neighbor channels.

• Results reported back to system to aid handoff decision.

• Designed to decrease dropped calls and improve handoffs.

• TDMA supports any combination of handoff between digital and analog channels.

• TDMA also supports handoff between 800 MHz and 1900 MHz cellular bands.

The Digital Control Channel

RACH SPACH BCCH SCF ReservedPCH

ARCH

SMSCH

F - BCCH

E - BCCH

S - BCCH

Digital Control Channel

Reverse Channel (RDCCH)

Forward Channel (FDCCH)

Forward DCCH Slot Structure

• SCF (Coded Superframe Phase)– Provides reverse DCCH access

control

• CSFP (Coded Superframe Phase)– Provides superframe phase

• CDL (Coded Digital Locator)– Provides DCCH .

• SYNC– Provides for slot synchronization

• CDVCC – Coded digital verification color

code

• DATA – 1/2 convolutional coding with

intraslot interleaving

SYNC SCF DATA SCF RSVDDATACSFP

28 130 130 10 212 12

Forward DCCH

SYNC SACCH DATA RSVD CDLDATACDVCC

28 130 130 1 1112 12

Forward DTCH

Subfields

Superframe Formation

TimeSlot

1

TimeSlot

2

TimeSlot

3

TimeSlot

4

TimeSlot

5

TimeSlot

6

TimeSlot

1

TimeSlot

2

TimeSlot

3

TimeSlot

4

TimeSlot

5

TimeSlot

6

Superframe - 32 slots (0.64 sec duration)

TimeSlot

1

TDMA Frame

TDMA Block

SFP= 0

SFP= 1

SFP= 2

SFP= 3

SFP= 4

SFP= 5

SFP= 6

SFP= 7

SFP= 8

SFP= 9

SFP= 30

SFP= 31

Superframe Composition

F-BCCH E-BCCH S-BCCH SPACH

F E S S... ... ...........

SFP 0 31

One Superframe = 16 TDMA frames = 640ms

... S

F-BCCH “Fast Broadcast Channel”

- Messages repeat every superframe

- Messages contain information critical for service on DCCH

E-BCCH “Extended Broadcast Channel”- Messages extended over multiple

superframes- Messages less time critical

S-BCCH “SMS Broadcast Channel”- Reserved for Broadcast SMS (IS-136B)

SPACH “SMS, Paging, and Access Channel”

- Used for sending Point-to-Point Messages

S

F-BCCH E-BCCH S-BCCH SPACH

F E S S S... ... ...........

0 31

One Superframe

... S

F-BCCH E-BCCH S-BCCH SPACH

F E S S S... ... ...........

0 31

One Superframe

... S

One Hyperframe = Two Superframes = 1.28s

The SPACH “SMS, Paging, and Access Channel”- Page messages (PCH)

- PCH messages are always repeated in secondary superframe- Access Response Messages (ARCH)

- ARCH messages are sent in idle SPACH slots (i.e. no page messages)- ARCH message may be sent over multiple superframes

- Teleservices messages (SMSCH)- SMSCH message are sent in idle SPACH slots- SMSCH message may be sent over multiple superframes

Superframes and Hyperframes

Sleepmode

• Sleepmode allows for battery savings• Various level of sleepmode are supported• Level of sleepmode is determined at registration• Mobile assigned PCH slot is determined by hashing

algorithm

0 1 2 3 4 5 6

1 2 3 4 5 6 7 8Superframe

Hyperframe

Paging FrameClass 1

Paging FrameClass 3

Paging FrameClass 2

9 10 11

12

13 14

Paging Frame Classes 4 through 8 not shown

(1) If mobile is unable to read PCH in primary superframe, it must try reading assigned PCH in secondary superframe

(2) If the system changes F-BCCH, the mobile is notified through system toggling of the BCN change flag in mobiles assigned PCH slot.

(3) Changes in the E-BCCH are indicated by a change flag in the F-BCCH.

Sleepmode Activities

Primary Superframe Secondary Superframe

12

3

Next Hyperframe

F SPACH..F E.. E S..S F SPACH..F E..E S.. S F..F E..E S..S

Reverse DCCH Slot Structure

6 6 16 28 122 24 122

G R PREAM SYNC SYNC+DATA DATA

Reverse DCCH

6 386 6 16 28 122 24 78

G R PREAM SYNC SYNC+DATA

Abbreviated Reverse DCCH

DATA

R AG

6 6 16 28 122 12 12 122

G R DATA SYNC SACCH CDVCCDATA DATA

Reverse DTC

• Two burst lengths are defined to accommodate both large and small cells

• SYNC+ provides additional synchronization information to the base station.

• PREAM aids base station automatic gain control to reduce signal distortion.

• AG provides 38 bits of guard for the abbreviated burst.

• G and R provides guard and ramp.

R-DCCH Multiple Access

• Subchanneling allows for multiple uplink paths

1 2 3 4 5 6 1 2 3 4 5 6 1 2 3

time expended

Uplink RACH Subchannels

TDMA frame 40 ms

1 2 3 4 5 6 1 2

DCCH Downlink Bursts

4 5 6 1 2 3 4 5 6 1 2 3 4 5 6

Phone checks slotavailability

First burst transmitted

Phones checksreception status

Additional burststransmitted

1

Layer 3 - 2 - 1 Mapping

L3DATA

Layer 3 Message

L2 HDR CRC

L3

L2 L3DATA CRCL2 HDR

Sync DATA DATACSFP SCFL1

DCCH Layer 3 Functionality

• Call processing, registration, and paging

• Mobile assisted channel allocation (MACA)

• Identity structures

• Cell selection

• Cell reselection

• Hierarchical cells

• Tiered services– Private/public systems

Call Processing

• Origination uses the same call model as IS-54B– Phone sends origination message to system on reverse DCCH– Traffic channel designation sent in base station response

• Paging on the DCCH– A phone is allocated a particular SPACH slot which is monitored for pages.– This allocation is based on the MIN of the phone

• Authentication– Same algorithms as used in IS-54B

Paging

• TDMA Paging – No rescan on reverse access channel removes the traditional

system border problems associated with analog.• Mobile responds to pages on the same DCCH as it receives pages on.

– Page message combination supports higher paging capacity• Single word paging uses one L2 frame per page

• Triple hard paging uses one L2 frame per three pages

• Standard allows for even further paging capacity through use of 20 and 24 bit TMSIs

– TDMA registration techniques allow for defining precise paging areas which can further increase messaging capacity.

Registration Types

• DCCH-based registration conditions are defined according to the following order of priority:

– Test registration New to TDMA– Power down – Deregistration New to TDMA– Power up – System transition condition Enhanced in TDMA– Location area (VMLA) New to TDMA– Periodic registration Enhanced in TDMA– ACC to DCCH transition New to TDMA

• The system broadcasts which forms of registration are supported on F-BCCH.

VMLA Registration

110

10

10

5

10

10

4

5

8

4

5

8

44

4

8

9

9

8

99

9

9

5 1

1

RNUM broadcast by cell.

RNUM list sent to mobiles at registration.

Mobile must register when unknown RNUM received.

Aspects of TDMA Registration

• TDMA-Based Registration– Several new registration types are added in TDMA

– Mobiles indicate the registration type they are responding to.

– The nuisance registrations can be reduced

– The registration defined to fully support private, public, and residential systems.

– VMLA-based registration • increases system control over paging load by tracking mobiles

based on location.• eliminates the ping-pong registration problem by defining

overlapping areas.

Through a proper configuration, a TDMA system can result in reduced registration traffic with greater paging efficiency.

Mobile Assisted Channel Allocation (MACA)

• MACA allows the mobile to provide the base station with a channel quality report upon access.

• Channel Quality Report– Long-term measurement - on serving DCCH: a running average over 32 frames

of RSS, WER, and BER.– Short-term measurement - on up to 15 channels specified by base: RSS based

on 4 measurements.

• The base station indicates the specific access types that the mobile is to provide a channel quality report.

• The MACA report can be used by the base station for enhanced channel assignment.

DCCH Selection

• Digital control channels can be placed on any channel within an operating band

• DCCH “pointers”– Coded DCCH Locator (CDL):

• The is sent within every forward digital traffic channel burst

• The CDL points to a location of a DCCH within a block channels. – Control Channel Information Word (CCI):

• The CCI word is sent as part of the ACCH overhead message. • The CCI contains a pointer to a single DCCH, the pointer includes the channel number,

DVCC, and hyperband of a DCCH.

– DCCH pointers are provided upon call release from both DTCs and AVCs.

– Probabilistic DCCH assignments may also be used.

DCCH Selection Process

• Exact DCCH selection procedures are mobile vender specific.

Scan history channels forlast used DCCH

Scan analog control channelsfor DCCH pointer

Scan probability blocks for DCCHor DTC with locator field

Cell Reselection Procedures

• TDMA cell reselection procedures are executed by mobiles while a mobile is in the idle state (i.e., sleepmode).

• Parameters broadcast by the base station gracefully steer mobiles to cells based on:– Mobility– Cell type (underlay or overlay)– Relative and absolute RF thresholds– Received signal strength– Private, public, residential

DCCH Neighbor Lists

• The DCCH neighbor list is central to the cell reselection process.

• Every DCCH broadcasts a neighbor list.

• The DCCH neighbor list provides mobiles with reselection parameters on all neighbor cells and sectors.– Mobiles use this information to choose the appropriate cell based mobility, desired network

type, etc.

• The neighbor list provides the mobile with all neighbor parameters needed for selection.– There is no need for a mobile to sync up and read neighbor cells prior to reselection

• An additional neighbor list may also be broadcast for alternate band (i.e. 800, or

1900MHz)

Signal Strength Measurements

• While in the idle state, the mobile maintain two sets of signal strength measurements.

• Long_RSS– Long_RSS is a running average of 5 measurements maintained for the serving DCCH in addition to all

neighbor DCCHs.

• Short_RSS is a running average 2 RSSI measurements

– Short_RSS is a running average of 2 measurements maintained for the serving DCCH only.

• Signal strength measurements are taken at a periodicity set by the base station.

With TDMA, there’s no need to sync up and demodulate neighbor channels in order to take a power measurement.

The Neighbor List Message

This field provides neighbor DCCH specific information as follows:

Field Length

CHAN 11

Protocol Version 4

DVCC 8

RESEL_OFFSET 7

SS_SUFF 5

DELAY 4

HL_FREQ 1

CELL_SYNC 1

CELLTYPE 2

Network Type 3

Directed Retry Channel 1

MS_ACC_PWR 4

RSS_ACC_MIN 5

PSID/RSID Indicator 1

PSID/RSID Support Length 0 or 4

PSID/RSID Support (Note1) 0 or 1 - 16

Neighbor Cell 1

Neighbor Cell 2

Neighbor Cell 3

Neighbor Cell 24

Neighbor List Message

Key Reselection Parameters

• RSS_ACC_MIN

– Minimum signal strength required for a phone to access a cell.

• RESEL_OFFSET– A hysteresis value used for adjacent cell reselection (i.e. cell type

regular).

• SS_SUFF

– The signal strength deemed sufficient for a phone to reselect a preferred or regular cell.

• MS_ACC_PWR

– Maximum power a phone can use to access a particular cell.

Reselection Parameters, Cont.

• Delay – Specifies the minimum time for which a

candidate cell must be seen at adequate signal

• CELLTYPE • Specifies a

Cell Reselection - Adjacent Cells

Example – Adjacent CellsExample – Adjacent Cells

Suggested Settings:

CELLTYPEB = REGULAR

DELAYB = 0

RESEL_OFFSETB = -3dB

Cell BoundaryAB

Macrocell (regular)

A

Macrocell (regular)

B

(RESEL_OFFSETB)+ (RESEL_OFFSETB)-

RESEL_OFFSET provides hysteresis between two adjacent cells

Cell Reselection - Delay

NL Delay – MicrocellsNL Delay – Microcells

mobile direction

RSS_ACC_MIN

DELAY

C D

Macrocell (overlay)

Microcell

A

B

Suggested Settings:

CELLTYPEB = Preferred

DELAYB = 1 or more hyperframes;

Delay should be set high enough to keep high mobility mobiles off microcell

Reselection - Underlay

SS_SUFFSS_SUFFExample – Underlaid Example – Underlaid Microcell Microcell

Assumptions:

HandoffBA = -85 dBm

Suggested Settings:

CELLTYPEB = PREFERRED

SS_SUFFB = -82 dB

DELAYB = 1 or higher

-82 dBm

Macrocell (non-preferred)

Microcell (preferred)

A

B

-72 dBm

SS_SUFFB

Total System Integration

Cell ReselectionCell Reselection

Private/PublicPrivate/PublicSystemsSystems

HierarchicalHierarchicalCellsCells

TDMATDMAC

apacity

Sea

mle

ss

Flexibility

Hierarchical Cells

• Hierarchical cell structures– Low power microcells overlaid by high power macrocells

• Why hierarchical cells ?– Flexible system growth/ increased capacity

• Low mobility traffic• In building• Hot spots/ cold stops

– Tiered services• Private and residential systems

– Capacity when and where you need it.– Extended mobile talk time

With TDMA, there’s no cumbersome power control issues involved in setting up low power underlayed cells.

Capacity: Cell Split Alternative

Cold Spot:Fill-in

A Capacity Tool - Hierarchical Cells

Due to hierarchical deployment, TDMA offers the best long-term RF capacity story

Capacity: Traffic Relief

Cold Spot: EconomicRemoteCoverage

Capacity:In Building Application

Tiered Services

Public

Residential

Workplace

Mall/ Airport, etc.

Types of Private Systems

• Virtual private systems– Semi-private systems

• Airport, mall, convention center

– Private only systems• Office parks

– Residential systems• Neighborhoods, suburbs

• Autonomous systems – Wireless PBX

• Companion microcell

ResidentialResidential

Tiered Tiered Service Service RegionsRegions

WPBXWPBX

PublicPublic

Basic Capabilities

• Capabilities provided through TDMA include:– Seamless system transition between private and

public systems

– Differentiated charging

– Alphanumeric display of serving system

– Underlays and in building support

– Private only or semi-private

– Possible to define multiple private systems off a single DCCH

Due to TDMA cell reselection and hierarchical deployment, TDMA offers strongest tiered services story.

The Mechanics of Tiered Services

• Cell Reselection Algorithms: – Seamless DCCH transition between public and private systems.

• Registration Procedures: – Assign and remove subscribers from system– Remove risk of nuisance registrations.

• System Identities: – Private and residential system IDs uniquely identify a system– Network type (3 bit map on the DCCH) defines a cell as public, private, residential, or

semiprivate.

• Alpha Tags: – Identify systems to subscribers by alphanumeric name.

• System Priorities: – Users rank private, residential, or public systems according to preference.

TDMA - Digital PCS

TDMA ScorecardTDMA Scorecard

Dual-Band Standard ¦ PCS at 800 & 1900 MHz

Terminals ¦ Dual-band, cost effective

Voice Quality ¦ EFRC MOS - wireline equivalent

Capacity ¦ N=5/4 reuse and underlays

Enhanced Services ¦ SMS, Over-the-Air Activation, Sleepmode, IS-41C, ...

In-building Services ¦ Hierarchical cell structure for underlays and WPBX

Data ¦ Circuit switched using IS-135High speed data evolution path

Roaming ¦ 1900 / 800MHz TDMA & AMPS Intelligent directed roaming

Fixed & Mixed ¦ Mobility, fixed, & mixed

Services and Design Examples

• Short message service features and examples• Over-the-air activation• Wireless office design example• Circuit switched data service• TDMA summary

Cellular Messaging

• Enables alphanumeric messages to be exchanged between the network and a DCCH capable phone.

• Message delivery is acknowledged.• Message attributes dictate phone behavior.• Includes two way messaging and in-call delivery.

base station

meeting isLarry: the

canceled

Larry: themeeting iscanceled

message

TNPP TAP

Voice

IS-41

. . . . . .. . . . . .. . . . . ...

MSC

e-mail

center

meeting is

canceled

Larry: the

. . . . . .

Larry: themeeting iscanceled

Messaging Examples

• One-way information services– News, stock quotes, sports scores.

– Broadcast services • Traffic, weather, etc.

• E-mail notifications– Containing “from,” “subject” and first part of message.

• Paging– Both one- and two-way paging with responses and acknowledgments.

• Platform for integrated messaging solutions– Voice mail, etc.

On-Air Activation

• Enables delivery of NAM information and updates to the phone over the air.

• Simplifies the activation process for both the subscriber and service provider.

• Provides a flexible download capability. • Provides a secure mechanism for A-key

updates.

WOS Design Example

• RF planning• Hierarchical cell structure design• System identities• Registration• Phone programming

Why Use a Hierarchical Cell Structure ?

• To bias the weaker cell

• Ease of design

MacrocellBase station

MacrocellBase station

Microcell

Microcell

HCS in an Indoor/Outdoor Site

MacrocellBase Station

Microcell

Microcell

R

P

NP

R

NP

P

P

NP

RR

P

NP

MacrocellBase Station

WOS Cell Configuration

macrocell 1

SS_SUFF

select macrocell 1

Neighbor cell relationships :R = Regular, P = Preferred,NP = Non-Preferred,SS_SUFF = Signal strength sufficient parameter

select office microcell select macrocell 2

macrocell 2

R

R

P

NP NP

P

System Identities

• Each cell can broadcast the following system identities– SID - same as today’s SID.

– SOC - system operator code indicating the cellular system operator.– PSID - private system identities used to distinguish private or WOS

systems.

• Network types can be assigned to each sector for service differentiation– Public

– Private– Residential– Or mixture (public and private, public and residential, etc.)

PSID Values

PSID Value (hex) Range and Function Use Match dependent

on0000 Unused

0001-2FFF SID-specific PSIDs WOS customers in single PSID, SIDSID area

3000-CFFF SOC-specific PSIDs WOS National accounts PSID, SOC

D000-DFFF Nationwide PSIDs Inter-carrier accounts PSID, MCC

E000-EFFF International PSIDs International accounts PSID

F000-FFFFReserved

SID and PSID Registration

SID = 47

SID = 33

SID = 33, PSID = 1000

REG

REG

REG

REG

REG

REG

SID Change Registration

PSID Change Registration

(when phone enters cell with different PSID status)

REG

REG

REGREG

SID = 33, PSID = 1000

SID Border

PSIDs and Location ID

Broadcast Parameters

SID = 47SOC = 801PSID1 = 1228PSID2 = 5760PSID3 = 2151PSID5 = 11127

EnterprisesAOB

AssociatesHawthorn

WirelessAT&T

MemorialGillarde

Hospital

HawthornAssociates

GillardeMemorialHospital

AT&TWireless

AOBEnterprisesInc

Inc.

Phone and System Configuration for Location ID

• System broadcasts SID, SOC and PSID.

• Phone is preprogrammed with SID, SOC and PSID parameters along with Alphatag– Alphatag is a system banner that the customer wants on the display of the phone.– Programming can be performed over the air.

• Depending on PSID type, phone will recognize WOS system using combination of SID, SOC and PSID.

• When phone enters WOS system, it will register when an identity match is made and will display the company banner or Alphatag.

• Phone will re-register upon leaving private system.

TDMA Data Services

• TDMA introduces a digital circuit-switched service for session- based transactions like fax and dial-up network access.

• Compare to packet data for short sporadic transactions.

Circuit-Switched and Packet Data

• Circuit-Switched Data – Transactions rely on a call being established.– Channel and resources are occupied by a single user.

– Efficient for fax, file transfers and where data is being exchanged for a high

proportion of the connect time.

• Packet Data– “Connectionless” service (no call setup overhead).– Many users share the same radio channel.– Efficient for short, bursty, sporadic transactions (like e-mail, web browsing

or virtual connections).

Transport Concept for Circuit- Switched Data

MSC

Layered Data Model

40 ms

IS-135

IS-130 IS-130

Digital Traffic Channel

TDMA frames

AT Commands andUser Data

Radio Link Protocol 1

Data Data DataData

Data Standards

• IS-130 - Radio Link Protocol– Error control – Compression– Encryption

• IS-135 - Async Data and Fax– Data call setup, supervision, and clearing– AT-command handling– Signal leads

TDMA - Air Interface

• TDMA Air Interface 800 and 1900 MHz

• Digital Control Channel– Same call control, reselection, HCS, roaming and private

system features.

• Digital Traffic Channel– Re-programmed for data or voice on a per call basis.

• Same Registration, Authentication and Handoff.

26

Radio Resources

• Uses same Digital Traffic Channel resources– Trunking efficiency– Configurable per call– Controlled by switch– Optimization and O&M the same as traffic

channels.

TDMA Features

• Perfect faxes delivered real-time at about two pages per minute.

• File transfers could be up to 115,200 bit/s with triple rate channel and compression (depending on data)

– Full Rate - 9.6 kbit/s uncompressed - 38.4 kbit/s compressed

• Detects and correct errors, compresses and encrypts data.• No special modem or fax machine required on wireline side.• Phone looks like a wireline fax/data modem.• Compatible with existing software.

– Future Windows unimodem will also contain built in support.

Throughput of Data Service

Throughput(bits/s)

*Depending on data and channel conditions

DTC Compressionoff

Compressionon

Full Rate 9,600 19,200 to38,400

TripleRate

28,800 57,000 to115,200*

Future Data Activities

• Multi-slot Operation– Concatenate timeslots to give higher throughput.

• Direct IP Connectivity.

• Browser Activity Increasing in TDMA Arena.

• Packet Data Transport in TDMA Environment– Standard in development– Provides integrated packet data solution for TDMA.

Future TDMA Features

• Broadcast Short Message Service

• Enhanced Talk Time– Discontinuous mode (DTX) with comfort noise doubles talk time

• Integrated TDMA Packet Data Solution

• Teleservice Transport Enhancements– Segmentation– Assignment to traffic channel for long messages

TDMA Benefits

• The DCCH is a method for rapid deployment of advanced services based on existing AMPs infrastructure.

• The DCCH is the platform for seamless 800 MHz and 1900 MHz PCS implementation.

• The DCCH offers new features to our customers.

TDMA Benefits - cont.

• Cost– TDMA can coexist with existing AMPS radios and frequencies.– Digital capability can be introduced when and where it’s needed.

– AMPs equipment can be selectively upgraded or redeployed.

• Capacity – TDMA introduces at least a threefold increase over AMPS capacity

• Even greater with use of Hierarchical Cell Structures, Adaptive Channel Allocation etc.

• Voice Quality – ACELP vocoder significantly improves voice quality.

• Roaming– Dual mode handsets and AMPS/TDMA compatibility ensures ubiquitous network

access.

TDMA Summary

• Enhanced Services Sleep mode Voice privacy Authentication Message waiting indicator Calling number identification Circuit switched data Short message service Private system features Hierarchical Cell Structures 800 and 1900 MHz Operation On air activation.