135943988-cdma2.pdf

7/28/2019 135943988-cdma2.pdf

1/126

Lucent Technologies ProprietaryThis document contains proprietary information of

Lucent Technologies and is not to be disclosed or usedexcept in accordance with applicable agreements

Copyright 1999 Lucent TechnologiesUnpublished and Not for Publication

All Rights Reserved

401-614-012Issue 6August, 1999

AUTOPLEX Cellular

Telecommunications System

System 1000

CDMA RF EngineeringGuidelines (Volume 2)

7/28/2019 135943988-cdma2.pdf

2/126

Lucent Technologies ProprietarySee notice on first page

Copyright 1999 Lucent Technologies

All Rights Reserved

Printed in U.S.A.

This material is protected by the copyright and trade secret laws of the United States and other countries. Itmay not be reproduced, distributed or altered in any fashion by any entity (either internal or external to LucentTechnologies), except in accordance with applicable agreements, contracts or licensing, without the expresswritten consent of the Customer Training and Information Products organization and the businessmanagement owner of the material.

For permission to reproduce or distribute please contact:

Product Development Manager 1 800 645 6759 (domestic)

1 317 322 6847 (international)

NoticeEvery effort was made to ensure that the information in this document was complete and accurate at the timeof printing. However, information is subject to change.

TrademarksAUTOPLEX is a registered trademark of Lucent Technologies.

Other trademarked terms may appear in this document as well. They are marked on first usage.

WarrantyLucent Technologies provides no warranty for this product.

Ordering InformationThe ordering number of this document is 401-614-012. To order this document, call the Lucent TechnologiesCustomer Information Center in Indianapolis, Indiana, on 1-888-582-3688, and ask for Operator 13.

Support Telephone NumberLucent Technologies provides a telephone number for technical assistance support from the WirelessTechnical Support Center (WTSC). The support number is:

Developed by Lucent Technologies Customer Training and Information Products organization.

1-800-225-4672

7/28/2019 135943988-cdma2.pdf

3/126

How Are We Doing?

Title:

Identification No.: Issue No.: Date:

Lucent Technologies welcomes your feedback on this Customer Information Product (CIP). Yourcomments can be of great value in helping us improve our CIPs.

1. Please rate the effectiveness of this CIP in the following areas:

2. Please check the ways you feel we could improve this CIP.

Improve the overview/introduction Make it more concise/brief

Improve the table of contents Add more step-by-step procedures/tutorials

Improve the organization Add more troubleshooting information

Include more figures Make it less technical

Add more examples Add more/better quick reference aids

Add more detail Improve the index

Please provide details for the suggested improvement.

3. What did you like most about this CIP?

4. Feel free to write any comments below or on an attached sheet.

If we may contact you concerning your comments, please complete the following:

Name: Telephone Number:

Company/Organization: Date:

Address:

When you have completed this form, please fold, tape and return to address on back

or Fax to: 336 727-3043.

Excellent Good Fair Poor

Not

Applicable

Ease of Use //////////////////

Clarity //////////////////

Completeness //////////////////

Accuracy //////////////////

Organization //////////////////

Appearance //////////////////

Examples

Illustrations

Overall Satisifaction //////////////////

AUTOPLEX Cellular Telecommunications Systems, System 1000 CDMA RF Engineering

Guidelines (Volume 2)

401-614-012 6 August, 1999

7/28/2019 135943988-cdma2.pdf

4/126

BUSINESS REPLY MAILFIRST CLASS PERMIT NO. 1999 GREENSBORO, NC

POSTAGE WILL BE PAID BY ADDRESSEE

NO POSTAGENECESSARY

IF MAILED

IN THEUNITED STATES

--------------------------------------------------------- Do Not Cut Fold Here And Tape -------------------------------------------------------------

DOCUMENTATION SERVICES2400 Reynolda RoadWinston-Salem, NC 27199-2029

7/28/2019 135943988-cdma2.pdf

5/126

Issue 6, August 1999 v


Contents

Chapter 1 - About This Document

Purpose 1-1

Technical Support Coverage 1-1

Scope 1-1

Intended Audience 1-2

Prerequisite Skills and Knowledge 1-2

Reason for Reissue 1-2

How to Use This Document 1-3How to Find Information on Related Customer

Documentation 1-5

How to Find Information on Related Customer Training 1-5

How to Comment on This Document 1-6

Chapter 2 - CDMA Overview

Concept 2-1

s Attributes 2-2

Capacity 2-2

Power Control 2-4

Soft Handoff 2-5

Voice Activity 2-5

s Deployment/Implementation Issues 2-6

Spectrum Clearance 2-6

Cell Site Locations 2-7

Boundaries 2-7

7/28/2019 135943988-cdma2.pdf

6/126

vi Issue 6, August 1999


Contents

Chapter 3 - Cell Site Architecture

Introduction 3-1

s Operation 3-2

s Series II CDMA Cell Site Equipment 3-2

Overview 3-2

Cell Site Components 3-4

Directional Cell Site Configuration 3-7

s CDMA System Capacities 3-9

Chapter 4 - Call Processing

Mobile Access 4-1

s Introduction 4-1

s Description of IS-95A Mobile Access Protocol 4-1

s Average Persistence Delay for Access Request Attempt 4-9

s Traffic, Throughput, and Delay Performance for IS-95A

Mobile Access Protocol 4-15

s Recommended Value of Access Parameters 4-23

Handoff 4-25

s Hard Handoff 4-25

s Soft and Softer Handoff 4-26

Definition 4-26

Procedure 4-26

Comparisons 4-27

Performance 4-29

Parameters 4-38

7/28/2019 135943988-cdma2.pdf

7/126

Issue 6, August 1999 vii


Contents

Chapter 5 - Packet Pipe Engineering

Introduction 5-1

s Simulation Model and Numerical Results 5-2

Assumptions 5-2

Packet Dropping Rate and Criterion 5-3

Numerical Results 5-3

Appendix A: CDMA Cellular Antenna Guideline

Introduction A-1

Antenna Concepts A-1

Antenna System with Interference and Cell Coverage A-3

s Directional Antenna and Sectorization Gain A-4

s Coverage with Antenna Height and Gain A-6

s Reducing Interference Using Antenna Downtilt A-7

Diversity Antenna Systems A-10

s Space Diversity Antenna A-10

s Polarization Diversity Antenna A-11

Appendix B: Antenna Isolation Guidelines for

Collocated RF Stations

Introduction B-1

Mathematical Models for Mutual Interference Evaluation B-1

s Receiver Desensitization B-3

s

Intermodulation Product Interference B-4s Receiver Overload B-5

Antenna Isolation Criteria and Safe Antenna Isolation B-6

7/28/2019 135943988-cdma2.pdf

8/126

viii Issue 6, August 1999


Contents

Example of Antenna Isolation Calculation B-7Antenna Separation Between Two Collocated

RF Stations B-11

Mutual Interference Between Multiple CollocatedRF Stations B-12

Site Survey B-15

Appendix C: References and Acronyms

References C-1

List Of Acronyms C-2

7/28/2019 135943988-cdma2.pdf

9/126

401-614-012

Contents

Issue 6, August 1999 1-i

Lucent Technologies - ProprietaryUse Pursuant to Company Instructions

1

About This Document

Purpose 1

Technical Support Coverage 1Scope 1

Intended Audience 2

Prerequisite Skills and Knowledge 2

Reason for Reissue 2

How to Use This Document 3

How to Find Information on Related CustomerDocumentation 5

How to Find Information on Related Customer Training 5

How to Comment on This Document 6

7/28/2019 135943988-cdma2.pdf

10/126

1-ii Issue 6, August 1999


Contents

7/28/2019 135943988-cdma2.pdf

11/126

Issue 6, August 1999 1-1


1

About This Document

Purpose

This document provides basic radio frequency engineering guidelines and

recommendations for use in the planning and design of a Code Division Multiple

Access (CDMA) cellular telecommunications system. These guidelines are

generic. Specific implementations will vary from system to system. All information

is consistent with the CDMA common air interface (IS-95A), minimum

performance standards for base stations (IS-97), and minimum performance

standards for mobile stations (IS-98).

Technical Support Coverage

Warranty and non-warranty support may be provided by several Lucent

Technologies organizations. The technical support may vary as outlined in specific

customer contracts and agreements. Your Lucent Technologies Account

Executive can provide details regarding the extent of your technical support

coverage.

Scope

This material comprises guidance, recommendations, and insights necessary to

optimally engineer a CDMA service system. Particular emphasis is given to

concepts such as power control that are key to successful system operation.

7/28/2019 135943988-cdma2.pdf

12/126

1-2 Issue 6, August 1999


401-614-012

All information is consistent with the CDMA common air interface (IS-95A),

minimum performance standards for base stations (IS-97), and minimum

performance standards for mobile stations (IS-98). These standards are listed in

the Chapter footnotes.

Intended Audience

This document is intended for system-level CDMA RF Engineers working in the

field who are planning new CDMA installations or adding to existing installations.

Prerequisite Skills and Knowledge

To use this document effectively, the user should have an in-depth understanding

of past analog and digital cellular telephone technologies with regard to RF

engineering.

Reason for Reissue

This is the sixth release of this document. CDMA technology is in an evolving

technology that is undergoing change on a day-by-day basis. Issue 6 brings the

document up to date with current applications being used in the field.

The size of the original document has increased over time making it necessary to

split this document into 2 documents. This document has been split into 2

documents, Volume 1 and Volume 2.

"Appendix E: Microcell RF Engineering Guidelines"has been removed from this

document (original document). A new document, the "FlexentTMPCS/Cellular

CDMA Microcell RF Engineering Guidelines" - 401-703-349, has been written to

replace Appendix E.

Chapter 9, contained a section on the Multiple-Carrier CDMA System. This

section has been removed from this document (original document). A new

document, the "Multi-carrier CDMA Systems RF Engineering Guidelines"

401-614-014, replaces the information in Chapter 9 of this document.

7/28/2019 135943988-cdma2.pdf

13/126



How to Use This Document

This document consists of Chapters 1 through 5 and Appendix A through C. You

are presently reading Chapter 1, About this Document.

This document is organized as follows:

s Chapter 1 About this Document Provides general information about

this document. It includes information regarding the intended audience,

organization and contents, how to order, and how to make comments.

s Chapter 2 CDMA Overview An overview of CDMA features is

presented here. This chapter summarizes CDMA concepts and operations,

and provides a basis for understanding the sections that follow.

s Chapter 3 Cell Site Architecture The CDMA cell site is based on the

existing Series II platform. Components such as RF combiners, linear

amplifiers, and antenna interface equipment can be shared by Advanced

Mobile Phone Service (AMPS) and CDMA. The CDMA specificcomponents must be housed in CDMA exclusive frames. The CDMA

components required for CDMA cell site implementation and configuration

are described in this chapter.

s Chapter 4 Call Processing The elements of call processing related to

mobile access and handoff are addressed.

In IS-95A, CDMA mobiles transmit on the access channels according to a

random access protocol. The packet throughput and delay performance of

the mobile access protocol are analyzed in terms of various mobile access

parameters. Based on the obtained numerical results from the analysis,

values of various parameters of the mobile access channels are

recommended.CDMA system supports several types of handoff. These include hard

handoff, soft handoff, and softer handoff. A mobile in hard handoff switches

from one cell site to another cell site by a brief interruption of the traffic

channel. Examples of hard handoff include handdown from CDMA system

to an analog system, and handoff from one CDMA carrier to another CDMA

carrier. A CDMA-to-CDMA hard handoff can also occur at the boundary

between different mobile switching centers.

Soft handoff is a technique whereby a mobile in moving between one cell

and its neighboring cells transmits and receives the same signal from

several cell sites simultaneously. On the forward link, the mobile in soft

handoff can combine the signals using appropriate diversity techniques.

On the reverse link, the Mobile Switching Center (MSC) can decide whichcell site is receiving stronger. In softer handoff, the mobiles call is

supported by neighboring sectors of the same cell. Proper use of soft and

softer handoff can enhance call quality, improving cell coverage and

capacity.

7/28/2019 135943988-cdma2.pdf

14/126



401-614-012

In soft handoff, mobile continuously scans for pilots, and establishes

communication with any cell (up to three) whose pilot exceeds a given

threshold. Similarly, communication with cells whose pilot drops below a

threshold is terminated. The operation of soft handoff is addressed in this

chapter. The values of various soft handoff parameters are alsorecommended.

s Chapter 5, Packet Pipe Engineering In this chapter, the number of

traffic channels that a packet pipe with a given bit rate can support is

determined.

s Appendix A, CDMA Cellular Antenna Guideline In wireless

communication systems, the antenna is one of the most critical

components that can either enhance or constrain system performance.

This Appendix addresses the antenna as a subsystem, including antenna

and feed, and how the antenna is designed to transmit or receive radio

waves. The basic function of an antenna is to couple electromagnetic (EM)

energy between free space and a guiding device such as a transmission

line, coaxial line, or waveguide. The orientation of the antenna plays a rolein improving capacity with a directional cell site. The directional antenna, as

a particular direction served to a sectored cell, can be used to increase

system capacity due to reducing the cochannel interference in CDMA

cellular communication systems. Antenna diversity is an important issue in

wireless communication systems. Multipath propagation due to many paths

(reflection, diffraction, and scattering) causes fading which results in rapid

variations in the received signal. The antenna diversity, such as space

diversity and polarization diversity at the base station or mobile, is received

by two separated antennas or an orthogonal polarized antenna to reduce

the severity of fading and to provide significant link improvement of the

reception.

s

Appendix B, Antenna Isolation Guidelines for Collocated RFStations Due to deployment constraints, estate acquisition difficulties

and other reasons, sometimes it is highly desired that CDMA cellular cell

sites (CSs) can be collocated with RF stations of other communications

systems such as TDMA PCS, CDMA PCS, Cellular TDMA, AMPS, AM,

SMR, etc. When they are collocated, mutual interference between stations

always exist that may cause receiver desensitization, overload and/or

Intermodulation Product (IMP) pollution, thereby degrading their system

performances. Therefore, if the service provider wants to collocate a CDMA

cellular CS with other RF station(s), precaution should be taken to avoid/

minimize those harmful mutual interferences. This Appendix addresses

these issues.

s Appendix C, References and Acronyms A list of references and

acronyms that are used within the document is provided.

7/28/2019 135943988-cdma2.pdf

15/126



How to Find Information on RelatedCustomer Documentation

Lucent Technologies product documentation can be ordered by mail using thefollowing address:

Lucent Technologies Customer Information Center

Attention: Order Entry Section

2855 N. Franklin Road

P.O. Box 19901

Indianapolis, IN 46219

Lucent Technologies product documentation can be ordered by phone using the

following numbers:

Within the United States:

1-888-582-3688

Ask for Operator 13

Locations outside of the United States:

Australia and all European countries: (317) 322-6416

North American (excluding U. S.), the Far East, and all other countries:

(317) 322- 6646

FAX for all international customers: (317) 322 - 6699

How to Find Information on RelatedCustomer Training

Lucent Technologies provides a complete set of training courses. For a complete

description of courses, see the Lucent Technologies Training Catalogand the

Lucent Technologies Technology Education Center Open Systems Education

catalog.

To order current catalogs from any location worldwide, call (International Access

Code) 1-614-764-5274.

To register for training or to inquire about training schedules, call the appropriate

telephone number from the following list:

s From within the United States: 1-800-TRAINER (1-800-872-4637)

s From locations outside the United States, call (International Access Code)1-614-764-5274.

7/28/2019 135943988-cdma2.pdf

16/126



401-614-012

How to Comment on This Document

We at Lucent Technologies have tried to make this document fit your needs, and

we are interested in your suggestions for improving this document.

Please send the name of this document and your comments to:

Lucent Technologies Bell Laboratories

1000 E. Warrenville Road

Naperville, Illinois 60566

U.S.A.

Attn.: Technical Publications - Room 1A-410

7/28/2019 135943988-cdma2.pdf

17/126



2

CDMA Overview

Concept 1

s Attributes 2

Capacity 2

Power Control 4Soft Handoff 5

Voice Activity 5

s Deployment/Implementation Issues 6

Spectrum Clearance 6

Cell Site Locations 7

Boundaries 7

7/28/2019 135943988-cdma2.pdf

18/126



Contents

7/28/2019 135943988-cdma2.pdf

19/126



2

CDMA Overview 2

Concept 2

CDMA is a multiple access concept based on the use of wideband spread

spectrum techniques that enable the separation of signals that are coincident intime and frequency. All signals share the same wideband spectrum. The energy in

each user's signal is spread over the entire bandwidth and coded so as to appear

like broadband noise to every other user. Individual signals are identified and

demodulated at the receiver by applying replicas of the coding used for each

signal. This process enhances the signal of interest, while dismissing all others as

broadband interference. This level of interference rises with the number of users.

Since a minimum signal-to-interference ratio is required to ensure call quality, the

total level of background interference ultimately limits system capacity;

consequently, all t ransmissions are carefully controlled in order to operate with the

least necessary power.

The CDMA concept can be contrasted with other multiple access techniques. In

Frequency Division Multiple Access (FDMA), each user has full-timeuse of partofthe spectral allocation. The allocation is divided into a number of narrowband

portions (channels). Each user's signal energy is confined to a channel. Signals

coincident in time are distinguished by using frequency-selective filters. In Time

Division Multiple Access (TDMA), each user has part-timeuse of allthe spectral

allocation. The allocation is broken down into a number of time slots. Each user's

signal energy is confined to a slot. Signals coincident in frequency are

distinguished through time gating. In CDMA, each user has full-time use of the

entire spectral allocation. Each user's signal energy is spread over the entire

bandwidth. Signals coincident in time and frequency are distinguished through the

use of coding unique to each signal.

7/28/2019 135943988-cdma2.pdf

20/126

CDMA Overview 401-614-012



Attributes 2

The chief rationale behind the deployment of a CDMA system is its potential for

high spectral efficiency; that is, its ability to support significantly more users within

a given bandwidth. Key system components such as power control and softhandoff are designed to realize and enhance this potential while maintaining

acceptable call quality. In addition, the modulation concept permits the offering of

such desirable system attributes as dynamic capacity and voice privacy.

In the following, key attributes of a CDMA system are summarized. More detailed

explanations can be found in the sections that follow.

Capacity 2

Capacity considerations are fundamental to CDMA planning and operation. For

the purpose of this discussion, capacity will be defined simply as the number of

users that can be simultaneously supported. Forward and reverse link capacitywill be addressed separately.

In each link, CDMA signals share the same wideband spectrum (carrier). Each

user's signal is coded so as to appear as broadband interference to every other

user. Power control minimizes the impact of this interference by adjusting each

signal level to the minimum necessary to achieve call quality. In the following,

these principles are applied to describe the dynamics of CDMA capacity.

Reverse Link 2

In order to place a call, a CDMA mobile must have sufficient power to overcome

the interference generated by all other CDMA mobiles within the band; that is, the

received signal at the cell site must achieve a required signal-to-interference ratio.The required mobile transmit power will thus depend on the distance of the mobile

from the cell site as well as on the total level of interference (that is, cell loading).

The establishment of each additional call raises the interference levels seen by all

users. Accordingly, to maintain call integrity, each user appropriately increments

its transmit power. These adjustments, in turn, raise the level of interference that

must be overcome by the next user. This process repeats itself until a new user

cannot achieve acceptable voice quality at the cell site. At this point, system

capacity has been reached.

The capacity limit occurs because the mobile stations eventually have insufficient

transmit power to overcome interference levels. The limit thus depends upon

factors that influence the level of interference seen at the cell site, for example,

traffic distributions within and outside the cell. Since the mobile restricts output

power when the user is not speaking, the limit will also depend upon the average

level of reverse link voice activity.

7/28/2019 135943988-cdma2.pdf

21/126




The many factors influencing CDMA capacity give rise to a desirable flexibility in

system operation. Since capacity is dependent upon interference levels, a cell's

capacity is inherently dynamic, that is, a cell can naturally absorb more users if

neighboring cells are lightly loaded. In addition, the system can naturally exploit

the reduced levels of interference generated by low voice activity. Finally, capacity

limits are soft rather than hard because system capacity can be increased by

lowering voice quality requirements. In this procedure, more users are supported

at the expense of slightly degrading the call quality of all users.

The flexibility described above makes it di fficult to exactly assess CDMA capacity

in a manner that will be applicable to all situations. As discussed in Chapter 4,

Reverse Link Capacity, a useful reference point can be obtained by assessing

the number of allowed users in an embedded cell when the power control is ideal

and the mobile transmit powers are not l imited. The maximum number of users

that can be supported under these circumstances is the "pole point" or "power

pole".

The values used in assessing pole point are tabulated in Chapter 4, Reverse LinkCapacity. For these figures, the pole point is approximately 27. This value applies

to a single sector of a directional cell. The pole point is obtained using 1.23 MHz

or 1/10 of the current cellular spectral allocation. In contrast, a single sector of an

FM system with frequency reuse of 7 will support about 2 channels within this

bandwidth. Thus, a CDMA system with significant capacity can be obtained by

implementing CDMA within a modest portion of the cellular band.

Forward Link 2

Upper limits on forward link capacity are fundamentally determined by restrictions

on cell site radiated power. The forward link signal comprises message traffic for

subscribers, a sector-specific signal (pilot) used by all mobiles, and miscellaneous

signals (for example, sync and paging). Total power is allocated among thesefunctions. Additional users cannot be supported when the sum of the allocations

required exceeds the available transmit power.

Required allocations are governed by the need for a minimum signal-to-

interference ratio at each mobile. The power allocated to other users within the

cell, as well as the received power from neighbor cell sites, contribute to this

interference. Interference from same-cell users is par tly mitigated by the use of

orthogonal codes which allow the receiver to suppress these signals; however,

multipath effects limit the extent to which this interference can be screened out.
http://../vol1/ch4.pdfhttp://../vol1/ch4.pdfhttp://../vol1/ch4.pdfhttp://../vol1/ch4.pdfhttp://../vol1/ch4.pdfhttp://../vol1/ch4.pdfhttp://../vol1/ch4.pdfhttp://../vol1/ch4.pdfhttp://../vol1/ch4.pdfhttp://../vol1/ch4.pdf

7/28/2019 135943988-cdma2.pdf

22/126




Forward link power distributions are further restricted by the requirement that a

generous fraction of power must be allocated to the sector pilot. The sector pilot is

important because it is used by all mobiles in site acquisition and tracking.

Capacity limits are therefore reached when the remaining power, distributed

among all users, is not enough to meet mobile signal-to-interference

requirements.

Power Control 2

As discussed above, capacity can be maximized by minimizing the total level of

system interference, that is, by controlling all CDMA signals to be at the lowest

level necessary to meet signal-to-interference requirements. Power control

ensures that each signal meets minimum requirements for communication while

not causing undue levels of interference to other signals.

Control is accomplished via a closed-loop algorithm on the forward link, and open-

and closed-loop algorithms on the reverse link. The open-loop mechanisms are

based on measurement of parameters known to influence the desired output,whereas the closed-loop mechanisms are based on direct measurements of the

output itself.

The objective of reverse link control is to ensure the minimum necessary signal-to-

interference ratio at the cell site for each mobile. In the open-loop path, the mobile

makes power adjustments based on its estimate of path loss from cell site to

mobile. This estimate is based on the mobile's measurement of received total

power. These adjustments compensate for path loss variations that are correlated

between the forward and reverse links. In the closed loop-path, the cell site

compensates for uncorrelated path loss variations (for example, multipath fading)

and additional sources of interference by measuring the received signal-to-

interference from the mobile and transmitting appropriate power adjustmentcommands. The final value of mobile transmit power is jointly determined by these

two control paths.

The objective of the forward link control is to ensure the minimum necessary

signal-to-interference ratio at each mobile from the cell site. In this closed-loop

mechanism, the mobile requests forward link power adjustments based on its

received FER.

7/28/2019 135943988-cdma2.pdf

23/126




Soft Handoff 2

In CDMA, various mechanisms are provided to ensure a robust handoff; that is, to

ensure call support when a mobile crosses the boundary from one cell to another.

The chief mechanism employed is "soft" handoff, where the mobile's call issimultaneously supported by up to three sectors. This process enables the mobile

to establish contact with the sectors that it is likely to proceed into well before it

leaves its serving (host) site. In addition, the simultaneous support provides a

diversity gain that improves link quality in "fringe" areas. The application of power

control from neighbor sites also ensures that a progressively distant mobile will

not unduly boost its transmit strength and become a primary source of

interference to a nearby cell site.

The CDMA soft handoff differs from the more familiar analog "hard" handoff in

several ways. In an analog system, cochannel interference is controlled by not

reusing the same channels in nearby cells. Accordingly, a mobile proceeding out

of one cell into another must switch its call to an available channel in the new cell.

This hard handoff requires a brief interruption of the traffic channel. In CDMA softhandoff, channel switching per se is not required because the same channel

(carrier) is reused in every cell. Moreover, the acquisition of new sites is

accomplished before contact with the old (serving) site is broken. No interruption

of the traffic channel occurs. This handoff procedure is robust because the

connection with the new host(s) is made before the connection with the old host(s)

is broken. This process is often referred to as a make-before-break connection, as

opposed to the analog break-before-make.

Voice Activity 2

Capacity may be enhanced through exploitation of voice activity. On the average,

each link in a two-way voice conversation is active about half the time. Iftransmitters vary output power with voice activity, the total interference power from

a large number of users will therefore be reduced by about a factor of two*. This

reduction in interference translates naturally into a direct increase in system

capacity. Such use of voice activity is possible because the same channel is

reused by all subscribers; in contrast, an analog FM system could exploit voice

activity only through the difficult task of reassigning the channel resource

whenever the speaker pauses.

* The actual reduction depends upon the level of channelactivity, which includes both voiceactivity as well as message activity (for example, power control). These considerations aredetailed further in Chapter 4.
http://../vol1/ch4.pdfhttp://../vol1/ch4.pdf

7/28/2019 135943988-cdma2.pdf

24/126




Deployment/Implementation Issues 2

Implementation of a CDMA system requires careful planning, particularly if the

system is to be deployed within an area already possessing analog service.

Deployment issues include clearance of spectrum, location of cell sites, boundaryhandoff (CDMA-to-analog) procedures, and cost. Several of these issues are

summarized below.

Spectrum Clearance 2

The use of CDMA requires a block of RF spectrum. In an isolated service area

with no pre-existing analog service, the spectrum required for each link is simply

the CDMA bandwidth (1.23 MHz). The spectrum requirement in an area with

analog capability within and outside its boundaries is more complex because

CDMA must coexist and interact with these other systems. In this situation, a

guard bandis required at carrier edges, and a guard zoneis required in the

surrounding area.

The objective of the guard band is to ensure that CDMA and spectrally adjacent

services do not interfere with one another. The spectrum requirement in the

service area thus comprises the CDMA bandwidth plus guard band. Spectrum is

required outside the service area as well. The CDMA bandwidth must be cleared

within the surrounding area (guard zone) in order to ensure that CDMA and

geographically adjacent services that employ the same carrier do not interfere

with one another. A modest guard band is also recommended within the guard

zone.

The use of the CDMA bandwidth by the analog system is forbidden within the

guard zone. This restriction results in a loss of analog capacity within this region.

This loss might be tolerated (as, for example, in a region of typically low traffic) orcompensated for by such means as microcells or TDMA.

Computations based on minimum performance standards indicate that a guard

band of 0.27 MHz on either side of the carrier is sufficient within the CDMA

service area. Accordingly, a total of 1.77 MHz must be set aside within the service

area for a single CDMA carrier. Some relaxation of this requirement may be

possible based on the specific performance of Lucent hardware. A reduced guard

band is required in the guard zone. Geographical guard zone requirements range

from 1 to 3 tiers of cells.

7/28/2019 135943988-cdma2.pdf

25/126




Cell Site Locations 2

In general, cell site locations must be chosen so as to meet coverage and capacity

objectives. Considerable flexibility in choice may be available in isolated areas

where analog capacity does not pre-exist. In contrast, cell site candidates in areaswhere analog capacity is already available should generally be restricted to

analog sites in order to reduce costs.

In areas with pre-existing analog capability, the CDMA system may be "overlaid"

on the existing analog system. Overlays may be 1:1 (that is, a CDMA cell

collocated with each analog cell) or n:1 (i.e., 1 CDMA cell for every n analog cells,

where n is greater than 1). In the latter process, a single CDMA cell encompasses

the equivalent area and traffic of more than one analog cell; however, many-to-1

overlays are not desirable due to the fact that the CDMA traffic capacity per

underlying analog cell is decreased. In addition, many:1 overlays could

compromise CDMA coverage as well as impair the ability of the CDMA system to

combat sources of external interference (see for example Mobile Receiver

Intermodulation, Chapter 2). In general, n:1 overlays with modest n (for example,between 1 and 2) are preferred, and 1:1 overlays are required in order to realize

the full benefit of CDMA capacity within every cell.

Deployment choices for a specific area entail a number of trade-offs. Collocating

CDMA sites with existing cell sites is generally preferred because it obviates the

need to acquire new sites and allows reuse of certain cell site equipment. A n-to-1

overlay needs less cell sites and entails less start-up cost, but requires careful

engineering to address issues of receiver overload (for example, a CDMA mobile

passing an analog site). A 1-to-1 overlay obviates these concerns but is more

expensive; however, the one-to-one correspondence facilitates CDMA-to-analog

handoff and may better accommodate future growth. Actual deployments could be

mixed, with n-to-1 in the interior of the service area and 1-to-1 at the boundary.

The latter choice might be made to facilitate boundary handoffs (see below).

Boundaries 2

Particular attention must be given to handoffs at a geographic boundary between

CDMA and an analog system. A mobile proceeding out of the CDMA service area

must hand-off to the analog system in order to maintain its call. Analog locate

radios do not detect CDMA mobiles; accordingly, mechanisms must be devised to

engineer the (hard) CDMA-to-analog handoff without the use of locate

information.

Such handoffs can be accomplished through associating analog channels with

each pilot in a CDMA border cell. A mobile served by that pilot may then hand-offto an analog channel before crossing the CDMA-analog border. Handoff across

the border is then analog-to-analog.
http://../vol1/ch2.pdfhttp://../vol1/ch2.pdfhttp://../vol1/ch2.pdfhttp://../vol1/ch2.pdfhttp://../vol1/ch2.pdfhttp://../vol1/ch2.pdf

7/28/2019 135943988-cdma2.pdf

26/126




An unambiguous mapping between CDMA pilot and analog channels permits the

CDMA-analog handoff without the use of locate information. Such mappings may

be established through 1-to-1 overlays, dualization, or CDMA beacons. The last

automatically hands off a CDMA call to preset analog channels.

The strategy for facilitating analog handoffs must entail careful cost trade-offs. In

particular, the cost of local infrastructure required to raise the probability of

success must be weighed against the cost of dropping some fraction of calls in a

boundary area that may serve little traffic. For example, overall CDMA cell count

might be minimized by adding infrastructure (for example, additional CDMA cells

or beacons) only in local boundary areas where a substantial amount of CDMA

traffic is anticipated to exit the CDMA service area.

7/28/2019 135943988-cdma2.pdf

27/126



3

Cell Site Architecture

Introduction 1

s Operation 2

s Series II CDMA Cell Site Equipment 2

Overview 2Cell Site Components 4

Directional Cell Site Configuration 7

s CDMA System Capacities 9

7/28/2019 135943988-cdma2.pdf

28/126



Contents

7/28/2019 135943988-cdma2.pdf

29/126



3

Cell Site Architecture 3

Introduction 3

A functional view of the Series II CDMA application is shown in Figure 3-1.

Figure 3-1. CDMA System Architecture

Control (RCC)

DS1

DFU

Analog

TDMA

CDMA

rf/ampl/dist

Control (RCC)

DS1

DFU

Analog

TDMA

CDMA

Control (RCC)

DS1

DFU

Analog

TDMA

CDMA

Series II

7/28/2019 135943988-cdma2.pdf

30/126

Cell Site Architecture 401-614-012



Operation 3

In the AUTOPLEXCDMA system, digital voice frames from mobiles are relayed by

the cell sites to the Speech Handlers (SHs) at the MSC for speech processing and

frame selection. The speech frames are in a packetized voice format using astandard protocol. A Digital Facilities Unit (DFU) provides interface between the

cell site and the DS1 facility linking the site to the MSC. The frame relay function is

performed by the 5ESS DCS switch.

The architecture of a CDMA system is similar to that of a traditional analog and/or

TDMA digital system except that the CDMA system requires speech processing

equipment at the MSC and new CDMA radio equipment at the cell site. In

addition, CDMA utilizes an embedded switching platform for switching CDMA

voice information.

The MSC will continue to support an Executive Cellular Processor (ECP) complex

and up to 16 DCSs. These DCSs can be in any combinations of 5ESS or G2

DCSs. There is no change in ECP hardware.

The 5ESS DCS performs the following:

s Speech processing

s Frame selection (for soft/hard hand-offs)

s Echo cancellation.

Series II CDMA Cell Site Equipment 3

Overview 3

This section describes and lists all new circuit packs and components necessary

to support CDMA in a given cell site configuration.

The CDMA cell site is based on existing Series II (SII) platform. The CDMA

system can easily be integrated with cell site also support ing AMPS, or TDMA, or

both AMPS and TDMA. The cell site is fully backward-compatible with the existing

analog (AMPS) and new digital (TDMA) systems.

While the Series II Primary Radio Channel Frame can contain the cell site

components for AMPS or TDMA, or both AMPS and TDMA, the CDMA specific

components must be housed in a CDMA-exclusive frame, the CDMA Growth

Radio Channel Frame. Once a frame is dedicated for CDMA support, neitheranalog AMPS nor digital TDMA components can be housed in that frame. A block

diagram to illustrate the frames of a SII and CDMA cell site is shown in Figure 3-2.

Also, as shown in Figure 3-3, components, such as, RF combiners, linear

amplifier, and RF equipment can be shared by the analog and CDMA systems.

R

7/28/2019 135943988-cdma2.pdf

31/126




Figure 3-2. SII /CDMA Cell Site Frames Block Diagram

Figure 3-3. SII Cell Site with CDMA and Analog Components

A SII cell site (SII-CS) can be implemented to support either an omni or up to six

sectors. In the case of microcells, each cell supports an omni or up to six

microcells. The CDMA Growth Frame consists of six shelves. Up to three CDMA

shelves can be interconnected to support combinations of three sector cells and/or microcells. When two or three adjacent shelves are interconnected, they will

transmit and receive at the same CDMA carrier frequency. In CDMA Release 1,

only three sectors and one carrier are supported. In CDMA Release 2.0 (and

beyond), full six sectors (one carrier) configuration will be supported.

L i n e a r

A m p l i f i e r

F r a m e 0

L i n e a r

A m p l i f i e r

F r a m e 1

A n t e n n a

I n t e r f a c e

F r a m e 1

C D M A

G r o w t h

R a d i o

C h a n n e l

F r a m e 1

C D M A

G r o w t h

R a d i o

C h a n n e l

F r a m e 2

A n t e n n a

I n t e r f a c e

F r a m e 2

( o p t i o n a l )

R F R F

R F

D S 1 I n p u t s

D a t a L i n k s &

V o i c e T r u n k s

G P S

S e r i e s I I

P r i m a r y

R a d i o

C h a n n e l

F r a m e 0

7/28/2019 135943988-cdma2.pdf

32/126




Major hardware required to support CDMA are:

s CDMA Digital Radio Frame(s)

s Global Positioning System (GPS) receiver

s CDMA Radio Test Unit (CRTU).

Cell Site Components 3

Shelf 3

A typical shelf layout for a CDMA application is shown in Figure 3-4.

Figure 3-4. CDMA SII-CS Shelf Layout

The CDMA specific components follows.

CDMA Channel Unit (CCU) 3

A CDMA Channel Unit (CCU) supports two identical channel elements. Each

channel element, in turn, provides the baseband spread spectrum signal

processing for a given channel.

Note that in rate set 2 applications the CCU becomes a TCU(See Appendix D,

CDMA Channel Unit (CCU)).

CDMA Cluster Controller CCC) 3

A CDMA Cluster Controller (CCC) supports call processing for each of the

channel elements and also provides interface between the CCU and the Radio

Control Complex (RCC). Packet pipe is terminated at the CCC.
http://../vol1/appd.pdfhttp://../vol1/appd.pdfhttp://../vol1/appd.pdfhttp://../vol1/appd.pdf

7/28/2019 135943988-cdma2.pdf

33/126




Analog Conversion Unit (ACU) 3

In the transmit direction, the Analog Conversion Unit (ACU) digitally combines

signals from the CCUs, performs D/A conversion, and limits the signal with a low-

pass filter. Each ACU has six analog outputs which represent the I and Q signalsto each of three sectors.

In the receive direction, the baseband signals from up to three Baseband

Combiner and Radios (BCRs) are sampled and sent to each channel element.

Baseband Combiner and Radio (BCR) 3

In the transmit direction, the Baseband Combiner and Radio (BCR) combines the

I and Q signals from each of the ACUs and converts the signals to RF with an up-

converter.

In the reverse direction, it receives RF signals and down-converts them to

baseband levels.

Bus Interface Unit (BIU) 3

A Bus Interface Unit (BIU) provides the interface between the BCR, ACU, and the

TDM bus. It also provides power conversion and alarm control functions.

Synchronized Clock and Tone (SCT) 3

Synchronized Clock and Tone (SCT) board provides the timing signals for the

CDMA system operation.

Digital Facilities Unit (DFU) 3

A Digital Facilities Unit (DFU) provides interface between the cell site and the DS1

facility linking the site to the MSC.

CDMA Radio Test Unit (CRTU) 3

A CDMA Radio Test Unit (CRTU) is used to perform the functional and diagnostic

tests either on a scheduled basis or on demand basis. This radio is placed in the

RCC shelf as shown in Figure 3-5.

7/28/2019 135943988-cdma2.pdf

34/126




Figure 3-5. RCC Shelf and Boards

The Linear Amplifier Frame (LAF) and Antenna Interface Frame (AIF) are the

same as the Release 5.0 cell site.

CDMA Radio Shelf Backplane 3

A new backplane is required for the radio shelves that suppor t CDMA

components.

Cabling Specifications 3

In a CDMA Radio Channel Frame unit, when multiple shelves are used to support

sectorized cells, coaxial cables are used to connect ACUs and BCRs across

shelves. In such cases, the lengths of connecting cables must be matched to

maintain equal propagation delays on various connections.

Redundancy and Reliability 3

To improve reliability of cell sites and to avoid a "single point" failure, two ACUs,

two BCRs, and two BIUs are maintained in each shelf. Similarly, there will be two

SCTs equipped for each TDM bus.

Global Positioning System (GPS) Receiver 3

The rubidium oscillator is in the AIF. The GPS receiver and its antenna are

mounted externally to the cell site frames (RCF, LAF, and AIF).

7/28/2019 135943988-cdma2.pdf

35/126




TDM Bus Configuration 3

In a CDMA cell, the configuration of the TDM Bus is similar to any TDMA SII-CS

configuration. The timing for the TDM bus is provided by the Synchronized Clock

and Tone (SCT) board. When needed for reliability and redundancy purposes, twoSCTs are placed in each even and odd addresses of a shelf of a cabinet.

Directional Cell Site Configuration 3

CDMA components include CDMA Channel Unit (CCU), CDMA Cluster Controller

(CCC), Analog Conversion Unit (ACU), Baseband Combiner and Radio (BCR),

and Bus Interface Unit (BIU). The location and interconnection of these

components of a 3-sector configuration are indicated in Figure 3-6. There are two

CCC's per shelf, each controlling up to 7 CCU's. The CCC also provides an

interface to the Time Division Multiplex (TDM) bus. A CCU comprises two

Channel Elements (CEs). Each CE supports a CDMA channel performing

baseband processing. The BIU controls TDM bus interface for the ACU and BCR.

In the forward link, the ACU (one per sector) digitally combines CCU outputs and

performs digital-to-analog (D/A) conversion to intermediate frequency (IF). Each

ACU can connect to all BCRs in order to support softer handoff. The BCR (one

per sector) combines the IF signals and up-converts to RF for transmission.

7/28/2019 135943988-cdma2.pdf

36/126




In the reverse link, the BCR down-converts RF to IF and distributes the signals to

the appropriate ACUs. The ACU A/D converts the IF to digital and passes the

signals to the CCUs.

Figure 3-6. 3-Sector Configuration

C D M A

C C C

A C U

B C R

C C U

C C UC C U

C D M A

C C C

D

F

U

C C U

L A F

A I F

&

A C U B C R

C D M A

C C C

C C U

C C UC C U

C D M A

C C C

C C U

B I U

B I U

A C U B C R

C D M A

C C C

C C U

C C UC C U

C D M A

C C C

C C U

B I U

C R T U

G P SS C T

7/28/2019 135943988-cdma2.pdf

37/126




CDMA System Capacities 3

This section summarizes major system capacities.

s The CDMA BHCA capacity is a percentage of the total BHCA capacity of

AUTOPLEXSystem 1000 product.

s The CDMA system handles up to 10 CDMA carriers (1.23 MHz each).

CDMA carriers can be re-used in every sector and every cell.

s A SII /CDMA cell site with two CDMA Growth frames support up to 336

channel elements (CEs).

s The MSC supports:

222 cell sites

17,000 trunks

30 packet pipes per cell site

s The 5ESS DCS supports:

The Packet Switching Unit (PSU) and the Switching Modules (SMs)

support at least 10000 BHCA.

The SM handles up to 108,000 BHCA

The PSU requires 35 speech handler cards to handle 10,000 BHCA

(assuming call holding time of 100 seconds).

7/28/2019 135943988-cdma2.pdf

38/126




7/28/2019 135943988-cdma2.pdf

39/126



4

Call Processing

Mobile Access 1

s Introduction 1

s Description of IS-95A Mobile Access Protocol 1

s Average Persistence Delay for Access Request Attempt 9s Traffic, Throughput, and Delay Performance for IS-95A Mobile

Access Protocol 15

s Recommended Value of Access Parameters 23

Handoff 25

s Hard Handoff 25

s Soft and Softer Handoff 26

Definition 26

Procedure 26

Comparisons 27

Performance 29

Parameters 38

7/28/2019 135943988-cdma2.pdf

40/126



Contents

7/28/2019 135943988-cdma2.pdf

41/126



4

Call Processing 4

Mobile Access 4

Introduction 4

In IS-95A [1], CDMA mobiles transmit on the access channels according to a

random access protocol. Detailed procedures of this random access protocol and

ranges of various access parameters can be found in TIA IS-95A Standard. In

references [4] and [5], protocol performance has been analyzed and appropriate

settings of mobile access parameters have been determined. Mobile Access

consists of five subsections. In Description of IS-95A Mobile Access Protocol,

the operation of the mobile access protocol and its associated parameters are

described. In Average Persistence Delay for Access Request Attempt, based on

reference [4], persistence delays for access request attempt are presented. In

Traffic, Throughput, and Delay Performance for IS-95A Mobile Access Protocol,

based on reference [5], traffic, throughput, and delay performance of the mobile

access protocol are presented. In Recommended Value of Access Parameters,settings of the various parameters associated with the mobile access channel are

recommended.

Description of IS-95A Mobile Access Protocol 4

As described in IS-95A, the mobile transmits on the access channel using a

random access procedure. A flow chart of the CDMA mobile access protocol is

shown in Figure 4-1. The entire process of sending one message and receiving

(or failing to receive) an acknowledgment for that message is called an access

attempt. Each transmission in the access attempt is called an access probe (see

Figure 4-2). The mobile transmits the same message in each access probe in an

access attempt. Each access probe consists of an access channel preamble andan access channel message capsule.

7/28/2019 135943988-cdma2.pdf

42/126

Call Processing 401-614-012



The length of the preamble as well as the length of message capsule

are expressed with the number of 20 millisecond frames. Thus,

the duration of an access probe (access channel slot) is

frames.

Within an access attempt, access probes are grouped into access probe

sequence. There are two types of messages sent on the access channel: a

response message (one that is a response to a base station message, see

Figure 4-3), or a request message (one that is sent autonomously by the mobile,

see Figure 4-4). Each access attempt consists of up to max_req_seq(for a

request access) or max_rsp_seq(for a response access) access probe

sequences.

The timing of the start of each access probe sequence is determined pseudo

randomly. For every access probe sequence, a backoff delay, RS, from 1 to

slots is generated pseudo randomly.

In the case for request access probe sequences, for each slot after the backoffdelay RS, the mobile performs a pseudo random persistence test. If the

persistence test passes, the first probe of the sequence begins in that slot. If the

persistence test fails, the access probe sequence is deferred until at least the next

slot. Thus, an additional delay, PD, is imposed by the use of a persistence test. For

each access channel slot, the persistence test generates a random number and

compares it with a pre-determined threshold. The pre-computed threshold is

different depending on the nature of the request, the access overload class nand

its persistence value psist(n) as well as its persistence modifier msg_psistfor

message transmission or reg_psistfor registrations.

Each access probe sequence consists of up to access probes, all

transmitted on the same access channel. The access channel number, RA, used

for each access probe sequence is chosen pseudo randomly from 0 to acc_chanamong all the access channels associated with the current paging channel. The

mobile will use this access channel number for all access probes in that access

probe sequence. The first access probe of each access probe sequence is

transmitted at a specified power level relative to the nominal open-loop power

level. Each subsequent access probe is transmitted at a power level a specified

amount PI(determined from pwr_step) higher than the previous access probe

until an acknowledgment response is obtained or the sequence ends. Between

access probes, the mobile will disable its transmitter.

The mobile transmits the first probe in each access probe sequence at a mean

output power level (referenced to the nominal CDMA channel bandwidth of 1.23

MHz) depending on open-loop power estimate, the initial power offset for access

init_pwrand the nominal transmit power offset nom_pwr.

1+ pam sz_3 + max cap sz_ _

4 + +pam sz max cap sz_ _ _

1+ bkoff

1+ num step_

7/28/2019 135943988-cdma2.pdf

43/126




The timing of access probes and access probe sequences is expressed in terms

of access channel slots. The transmission of an access probe begins at the star t

of an access channel slot. The precise timing of the access channel transmissions

in an access attempt is determined by a procedure called PN randomization. For

the duration of each access attempt, the mobile computes a delay, RN, from 0 to

PN chips using a (non-random) hash function that depends on its

electronic serial number ESN. The mobile delays its transmit timing by RNPN

chips. This transmit timing adjustment includes delay of the direct sequence

spreading long code and of the quadrature spreading I and Q pilot PN sequence,

so it effectively increases the apparent range from the mobile to the base station.

This increases the probability that the base station will be able to separately

demodulate transmissions from multiple mobiles in the same access channel slot,

especially when many mobiles are at a similar range from the base station.

Timing between access probes of an access probe sequence is also generated

pseudo randomly. After transmitting each access probe, the mobile waits a

specified period, milliseconds, from the end of the slot to

receive an acknowledgment from the base station. If an acknowledgment isreceived, the access attempt ends. If no acknowledgment is received, the next

access probe is transmitted after an additional backoff delay RT, from 1 to

slots.

2probe pn ran_ _

( )TA acc tmo= +80 2 _

1+ probe bkoff_

7/28/2019 135943988-cdma2.pdf

44/126




7/28/2019 135943988-cdma2.pdf

45/126




Figure 4-1. CDMA Mobile Access Protocol

7/28/2019 135943988-cdma2.pdf

46/126




Figure 4-2. Mobile Access Probe

7/28/2019 135943988-cdma2.pdf

47/126




Figure 4-3. Mobile Access Response Attempt

7/28/2019 135943988-cdma2.pdf

48/126




Figure 4-4. Mobile Access Request Attempt

7/28/2019 135943988-cdma2.pdf

49/126




Average Persistence Delay for Access RequestAttempt 4

As discussed in Description of IS-95A Mobile Access Protocol, for access due to

mobile request, TIA IS-95A requires that persistence test be performed prior toinitiating the access probe sequence in order to control the rate at which the

mobile transmits request. To assess the appropriate range of persistence values

to be assigned to the mobiles, the amount of delays due to persistence tests are

needed. In this section, based on reference [4], average persistence delays as a

function of persistence values are calculated for various types of request and

access overload classes.

For each access channel slot, the persistence test generates a random

number and compares it with a pre-determined threshold . If

the generated random number RPis smaller than the pre-determined threshold

P, access probe sequence is initiated. Since the random number is generated

from uniform distribution over the unity interval, thus

In other words, the larger implies the higher probability to initiate the access

probe sequence.

The pre-computed threshold , in general, is different depending on the nature

of the request, the access overload class, and its persistence value , as

well as its persistence modifier. As an example, for registration request of access

overload classes 0 through 9, if , then , thus the persistence

test fails, and no access probe sequence is initiated; if is not equal to 63,

for a given persistence modifier , is monotonic, decreasing function of

; the largest , the smaller , thus the smaller probability to initiatethe access probe sequence. Table 4-1 summarizes the persistence test

thresholds for various types of requests and access overload classes.

From Table 4-1, it is noted that maximum persistent value is 63 for access

overload classes 0 through 9, and is 7 for access overload classes 10 through 15.

If the maximum persistent value is assigned to the mobile, the access attempts

fails, and the mobile enters the system determination substateof the mobile

initialization state[1].

( )0 1<

7/28/2019 135943988-cdma2.pdf

50/126




For persistence value not equal to the maximum, random persistence delays canbe incurred to control the transmissions of mobile requests. The persistence delay

PDis the number of times to perform the tests before the condition is

satisfied. Thus, persistence delay PDis a random variable, and its discrete

probability density is geometric with parameter P, that is,

One performance measure to characterize the persistence test is the average

persistence delay. Let be the expectation operator. The average persistence

delay is:

Using the values of persistence test thresholds Pin Table 4-1 for various types of

requests and access overload classes, Table 4-2 summarizes their average

persistence delay .

Table 4-1. Persistence Test Thresholds for Registration,Message, and Other Requests

Persistence Test Threshold

access overload classes access overload classes

Registration Request 0 0

Message Request 0 0

Other Request 0 0

P

n= 0 1 9, , , n=10 11 15, , ,

( )psist n 63 ( )psist n = 63 ( )psist n 7 ( )psist n = 7( )

2 4

psist nreg psist_

( )2 psist n reg psist_

( )

2 4

psist nmsg psist_ ( )2

psist n msg psist_

( )

2 4

psist n( )2

psist n

RP P

Documents

135943988-cdma2.pdf