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Code Division Multiple Access (CDMA) :

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  1 Code Division Multiple Access (CDMA)

AI-CDMA:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  2 AI-CDMA © Copyright 2001 Global Wireless Education Consortium All rights reserved. This module, comprising presentation slides with notes, exercises, projects and Instructor Guide, may not be duplicated in any way without the express written permission of the Global Wireless Education Consortium. The information contained herein is for the personal use of the reader and may not be incorporated in any commercial training materials or for-profit education programs, books, databases, or any kind of software without the written permission of the Global Wireless Education Consortium. Making copies of this module, or any portion, for any purpose other than your own, is a violation of United States copyright laws. Trademarked names appear throughout this module. All trademarked names have been used with the permission of their owners .

AI-CDMA:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  3 AI-CDMA Partial support for this curriculum material was provided by the National Science Foundation's Course, Curriculum, and Laboratory Improvement Program under grant DUE-9972380 and Advanced Technological Education Program under grant DUE‑9950039. GWEC EDUCATION PARTNERS: This material is subject to the legal License Agreement signed by your institution. Please refer to this License Agreement for restrictions of use.

Table of Contents:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  4 Table of Contents Overview 5 Learning Objectives 6 CDMA Implementation 7 CDMA Network 10 CDMA Concept 14 CDMA Cell Structure 25 CDMA Channels 30 CDMA Handoffs 36 CDMA Forward Voice Path 40 CDMA Reverse Voice Path 49 Summary 57 Contributors 60

Overview:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  5 Overview This module covers the following topics: CDMA Implementation CDMA Network CDMA Interfaces CDMA Channel Structure CDMA Voice Paths

Learning Objectives:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  6 Learning Objectives After completing this module, you will be able to: Explain how a CDMA system works Describe CDMA interfaces, channel structure, and cell structure

CDMA Implementation:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  7 CDMA Implementation

CDMA History:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  8 CDMA History Early 1989 NADC IS-54 established CDMA development started Proposed by Qualcomm Late 1989 First demonstration May 1995 IS-95A standard published by TIA committee TR45.5 Dec. 1995 TSB-74 introduces 14400 bps TCH June 1996 J-STD-008 CDMA PCS standard July 1998 IS-95B (a consolidation of J-STD-008 and TSB-74) 3rd Generation (3G)

CDMA Around the World:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  9 CDMA Around the World Israel USA Singapore Philippines Korea Japan

CDMA Network:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  10 CDMA Network

CDMA:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  11 CDMA Slide capacity depends on mutual interference between user codes Accumulative interference between many codes can exceed the tolerable level Interference rejection ratio A function of code rate and information rate Known as the processing gain

CDMA Network:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  12 CDMA Network Interface to other networks MS MS BTS BTS BTS BS BS MSC MSC MSC MSC VLR VLR HLR EIR AuC OS BSC BTS BTS BTS BSC 1 2 4 5 7 8 * 0 3 6 9 #

CDMA Network Interfaces:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  13 CDMA Network Interfaces PSTN Analog Interface using DTMF or MF signaling Internal Interface Defined SS7 ISDN BRI/PRI Frame Relay Ai Interface RF Test Equipment 1 2 4 5 7 8 * 0 3 6 9 # 1 2 4 5 7 8 * 0 3 6 9 # 1 2 4 5 7 8 * 0 3 6 9 # BTS BTS BTS BSC BSC BSC MSC MSC MSC Um Interface Abis A Interface Air Interface

CDMA Concept:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  14 CDMA Concept

PowerPoint Presentation:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  15 Direct Spread Frequency Hopping

CDMA Communication:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  16 CDMA Communication FDMA and TDMA CDMA

Alternative CDMA Communication:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  17 Alternative CDMA Communication Original message is modulated by PRBS signal Spectrum is produced that spreads over a wide bandwidth During detection process, receivers compare received signal with PRBS code Receivers with same PRBS that encoded the message can detect presence of the message Message is detected and coded All other receivers see PRBS encoded message as noise Presence of slightly increased noise level

CDMA Paradigm – Forward Channels:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  18 CDMA Paradigm – Forward Channels Forward channels Channelized by digital codes called Walsh codes Pilot = Walsh Code 0 Sync = Walsh Code 32 Paging = Walsh Code 1 to 7 Traffic = Any unused Walsh codes

Base Stations and PNs:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  19 Base Stations and PNs All base stations use same PN sequence Each base station selects from 512 different PN off-sets Mobile station synchronizes to a pilot channel Each base station has GPS receiver to synchronize self with alls other bases stations Timing accuracy is vital to CDMA system functionality

CDMA Paradigm – Reverse Channels:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  20 CDMA Paradigm – Reverse Channels Channelized by digital codes called long codes masked by a unique user long code mask Long code is a 42 bit number - 4.3 billion combinations Each mobile has a different long code mask Two types of reverse channels: Traffic channels Access channels

CDMA Capacity:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  21 CDMA Capacity Capacity limit is fixed at 8 x number of ARFCNs per cell Capacity limit is ‘soft’, Increases with decrease in quality

CDMA Capacity :

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  22 CDMA Capacity What? It’s getting loud in here!

CDMA Modulation and Demodulation:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  23 CDMA Modulation and Demodulation f c f c 0 0 Walsh Code Spreading Walsh Code Correlator Baseband Data Baseband Data Decoding & Deinterleaving Encoding & Interleaving

CDMA Power Control Acquisition Only:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  24 CDMA Power Control Acquisition Only 1 2 4 5 7 8 * 0 3 6 9 # Too much power Interference Low talk time Too little power Dropped calls Receive + Transmit Power = -73 dB Assume forward and reverse losses are equal

CDMA Cell Structure:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  25 CDMA Cell Structure

PowerPoint Presentation:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  26 Source Lucent Technologies

Omni Cell:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  27 Omni Cell Cell Omnidirectional Antenna

Sectored Cell:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  28 Sectored Cell Sector Sectored Antenna Cell

CDMA Cell Plan:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  29 CDMA Cell Plan 1 1 1 1 1 1 1 1 1

CDMA Channels:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  30 CDMA Channels

CDMA Pilot Channel:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  31 CDMA Pilot Channel 1 2 4 5 7 8 * 0 3 6 9 # Pilot Channel 1 Pilot Channel 3 Pilot Channel 2 Sector 2 Sector 3 Sector 1

CDMA Pilot Channel:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  32 CDMA Pilot Channel Carries frequency reference Carries time reference Used by mobile to recover the data from received codes by ‘clock recovery’

CDMA Traffic Channel:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  33 CDMA Traffic Channel 1 2 4 5 7 8 * 0 3 6 9 # Forward Link Traffic Channel Reverse Link Traffic Channel

CDMA Synchronization Channel:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  34 CDMA Synchronization Channel SID and NID of cellular system Channel number Carries PN offset of base station Long code state System time Local time offset from system time Leap seconds from start of system time

CDMA Paging Channel:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  35 CDMA Paging Channel Access parameters controlling how mobile station initiates calls Channel assignment and list that controls how mobile station is assigned a traffic channel and which channels are available Neighbor lists of PN offsets for surrounding base stations Authentication

CDMA Handoffs: Soft Handoff and Hard Handoff:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  36 CDMA Handoffs: Soft Handoff and Hard Handoff

CDMA Soft Handoff:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  37 CDMA Soft Handoff 1 2 4 5 7 8 * 0 3 6 9 # Channel 1 Channel 2 Sector 2 Sector 1

CDMA Softer Handoff:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  38 CDMA Softer Handoff Channel 1 Channel 2 Sector 2 Sector 1 1 2 4 5 7 8 * 0 3 6 9 #

CDMA Hard Handoff and Hand-Down:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  39 CDMA Hard Handoff and Hand-Down 1 2 4 5 7 8 * 0 3 6 9 # Channel 1 Channel 2 1 2 4 5 7 8 * 0 3 6 9 # Sector 2 Sector 1

CDMA Forward Voice Path:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  40 CDMA Forward Voice Path

CDMA Forward Voice Path:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  41 CDMA Forward Voice Path Vocoder Interleave Modulator Power Correct Error Privacy Voice Control Channelize Coverage

CDMA Forward Vocoder:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  42 CDMA Forward Vocoder Vocoder Vocoders take analog voice and turn it into digital bit stream, utilizing data compression Different sampling rates produce different speech quality for a particular output data rate 3 types of CDMA vocoders: IS-95A : Variable 8 kbps, moderate quality CDG : Variable 13 kbps, near toll quality EVRC : Variable 8 kbps, toll quality 9.6 kbps or 14.4 kbps

CDMA Forward Error Correction:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  43 CDMA Forward Error Correction CDMA presently uses 2 types of convolutional coders to add error correction in forward path If data is full rate (14.4 kbps) or 9.6 kbps encoding is different At 9.6 kbps, a 1/2 rate convolution coder is used At 14.4 kbps, a 3/4 rate convolution coder is used Correct Error always 19.2 kbps output 14.4 kbps 9.6 kbps

CDMA Forward Interleave:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  44 CDMA Forward Interleave leave Inter OUTPUT AEJO BFKP CGLQ DHMR A B C D E F G H J K L M O P Q R INPUT ABCD EFGH JKLM OPQR ABCD EFGH JKLM OPQR 19.2 kbps 19.2 kbps CDMA uses a matrix system for interleaving Data is input to 4 x 4 matrix in rows and output in columns

CDMA Forward Voice Privacy:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  45 CDMA Forward Voice Privacy Used in forward channel to provide some privacy Measure of voice privacy, but scrambling data XOR Decimator Masked long code data 1.2288 mbps 19.2 kbps Scrambled voice data 19.2 kbps Encoded voice data 19.2 kbps

CDMA Forward Power Control:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  46 CDMA Forward Power Control Closed loop power control bits ‘punctured’ into data stream Bit locations controlled by decimated long code PC MUX Long Code data 1.2288 mbps 800 bps Output voice data 19.2 kbps Scrambled voice data 19.2 kbps Closed Loop Power Bits Decimator

CDMA Forward Channelization:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  47 CDMA Forward Channelization Each bit of voice data is ‘spread’ by 64bits Each Walsh code has 64 bits XOR Walsh code generator 1.2288 mcps Output Walsh coded data 1.2288 mcps Encoded voice data 19.2 kbps X Y

CDMA Forward Coverage:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  48 CDMA Forward Coverage Short code ‘covers’ the Walsh codes Allows reuse of Walsh codes between cells Time offset short codes provide base station identity I Channel Short Code Walsh coded data 1.2288 mcps To IQ modulator Q Channel Short Code

CDMA Reverse Voice Path:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  49 CDMA Reverse Voice Path

CDMA Reverse Voice Path:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  50 CDMA Reverse Voice Path Spreading Data Channelize Scrambling Vocoder Interleave Correct Error Modulator

CDMA Reverse Vocoder:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  51 CDMA Reverse Vocoder Vocoders take analog voice and turn it into a digital bit stream, utilizing data compression Different sampling rates produce different speech quality for a particular output data rate Vocoder 3 types of CDMA vocoders: IS-96A : Variable 8 kbps, moderate quality CDG : Variable 13 kbps, near toll quality EVRC : Variable 8 kbps, toll quality Maximum 9.6 kbps or 14.4 kbps

CDMA Reverse Error Correction:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  52 CDMA Reverse Error Correction CDMA uses two types of convolutional coders to add error correction in reverse path If data is full rate (14.4 kbps) or 9.6 kbps, encoding is different Correct Error Always 28.8 kbps output 14.4 kbps 9.6 kbps At 9.6 kbps, 1/3 rate convolution coder is used At 14.4 kbps, 1/2 rate convolution coder is used

CDMA Reverse Interleave:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  53 CDMA Reverse Interleave CDMA uses a matrix system for interleaving Data is input to 4 x 4 matrix in rows and output in columns leave Inter OUTPUT AEJO BFKP CGLQ DHMR A B C D E F G H J K L M O P Q R INPUT ABCD EFGH JKLM OPQR ABCD EFGH JKLM OPQR 28.8 kbps 28.8 kbps

CDMA Reverse Data Spreading:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  54 CDMA Reverse Data Spreading Used in reverse link to provide data spreading to 307.2 kcps and randomize data in easy-to-recover scheme 64ary Modn Spread voice data 307.2 kcps Encoded voice data 28.8 kbps Output 64 bits (1 of 64 Walsh Codes) Input 6 bits (64 values)

CDMA Reverse Channelization:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  55 CDMA Reverse Channelization Long code is used to provide channelization Walsh codes not used; they would provide only 64 channels compared to 4.3 billion XOR Masked Long Code Data 1.2288 mcps Output Long coded data 1.2288 mcps Walsh modulated voice data 307.2 kbps

CDMA Reverse Scrambling:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  56 CDMA Reverse Scrambling Short code used for sequence scrambling half-chip delay removes zero crossings on IQ modulation and leads to simpler amplifier design I Channel Short Code Walsh Coded Data 1.2288 mbps To IQ modulator 1.2288 mbps Q Channel Short Code 1/2 Chip Delay

Summary:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  57 Summary

Summary:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  58 Summary Uniqueness of CDMA Frequency reuse of one Tight power control Longer battery life CDMA supports soft handoff

CDMA Benefits:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  59 CDMA Benefits High capacity without hard blocking limits Easy frequency planning Greater coverage with fewer cells Technology platform extendable to new services Excellent call quality Inherent privacy Lower power/Longer battery life

Industry Contributors:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  60 Industry Contributors Ericsson ( http://www.ericsson.com ) Nortel Networks ( http://www.nortel.com ) Telcordia Technologies, Inc ( http://www.telcordia.com ) Verizon ( http://www.verizon.com ) The following companies provided materials and resource support for this module:

Individual Contributors:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  61 Individual Contributors The following individuals and their organization or institution provided materials, resources, and development input for this module: Dr. C haouki Abdallah University of New Mexico http://www.eece.unm.edu/ Dr. Tad Babij Florida International University http://www.eng.fiu.edu/ Dr. Jeff Cobb Verizon Wireless http://www.verizonwireless.com/ Mr. Ron Koziel KnowledgeLink, Inc. http://www.knowledgelinkinc.com/

Individual Contributors, cont.:

June 2001 Copyright 2001 Global Wireless Education Consortium AI-CDMA  62 Individual Contributors, cont. Dr. Peter Rha San Francisco State University http://www.sfsu.edu/ Dr. Cheng Sun California Polytechnic State University http://www. calpoly.edu/ Mr. Richard Van Cleave Nortel Networks http://www.nortel.com / Dr. David Voltmer Rose-Hulman Institute of Technology http:// rose-hulman.edu /

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