Embed Size (px)
Citation preview
CDMA Fundamentals
2
Agenda
• CDMA introduction• CDMA makes use of Diversity• Power control• CDMA Forward Link • CDMA Reverse Link• CDMA call processing• CDMA Measurement
3
Cellular Access Methods
Power Time
FrequencyFDMA
Power Time
Frequency
Power
Time
Frequency
TDMA
CDMA
4
User #3
Frequency Domain
User #2User #1
SynchPaging
Pilot
1.2288 MHzfreq
Code Domain
0 1 2 3 4 5 6 7 8 9 32 40 63User
1User
3User
2
Walsh Code
Pilot Paging Synch
Code Domain Power (cdma2000/IS-95)
The CDMA Concept
5
CDMA is Also Full Duplex
US Cellular Channel 384Amplitude
FrequencyAMPS
CDMAFrequency
Amplitude
Reverse Link
Reverse Link
Forward Link
Forward Link
45 MHz
45 MHz
836.52 MHz
836.52 MHz 881.52 MHz
881.52 MHz
6
Code Division Multiple Access
What is CDMA ?
• Spread spectrum technique• Multiple users share the same frequency in one cell• Same frequency in all the cells• Operates under presence of interference• Takes advantage of multipath• Capacity is soft
7
Cellular Frequency Reuse Patterns
3
6
CDMA Reuse FDMA Reuse
11
1
1
11
11
16
22
1
45
7
8
The CDMA Concept
BasebandData
Encoding &Interleaving
Walsh CodeSpreading
Walsh CodeCorrelator
BasebandData
Decode & De-Interleaving
0 0fcfc
fcfcfcfc
10 Khz BW 1.23 Mhz BW 10 Khz BW1.23 Mhz BW
1.23 Mhz BW1.23 Mhz BWSpurious Signals-113 dBm/1.23 Mhz
CDMATransmitter
CDMAReceiver
9.6 kbps 19.2 kbps 1228.8 kbps 9.6 kbps19.2 kbps1228.8 kbps
Background Noise External Interference Other Cell Interference Other User Noise
Interference Sources
9
Multiple user data can be spread by using combinations of this PN code
Direct Sequence Spread Spectrum
• Baseband data multiplied by a Pseudo Random Noise (PN) Code, which is a sequence of chips valued -1 & +1 or 0 & 1
• PN code is a noise-like code with certain properties (ex: orthogonal)
10
Direct Sequence Spread Spectrum
• Direct sequence spread spectrum signal is generated by multiplying narrowband user data with a well-defined wideband pseudo-random sequence.
• Recovering the narrowband user data is achieved by multiplying the received signal by an identical, accurately timed pseudo-random sequence.
Direct Sequence Spread Spectrum
Power Spectral Density
Freq
Direct sequence spread signal
Narrowband user data
11
Direct Sequence Spread Spectrum
Source Information Bits
I-Q Modulator
CarrierCode Generator Bit Stream
Transmit DSSS Signal
Block diagram of a Direct Sequence Spread Spectrum Transmitter
Bits to I-Q
12
Direct Sequence Spread Spectrum
Received DSSS signal
Code Synchronization Code Generator
Demodulator
Carrier
Data
Block diagram of a Direct Sequence Spread Spectrum Receiver
13
What is Correlation ?
• Is a Measure of How Well a Given Signal Matches a Desired Code
• The Desired Code is Compared to the Given Signal at Various Test times
Received Signal
Time
Correlation = 1
Correlation = 0
Correlation = 0
Correlation = 0
14
Auto-Correlation
• Is a Comparison of a Signal Against Itself
• Good Pseudo-Random Patterns Have:
Strong Correlation at Zero Time OffsetWeak Correlation at Other Time Offsets
Pseudo-Random Sequence
Auto-Correlation Versus Time Offset
1
0
1
300 5 10 15 20 25
0 10 205 15 25 30
0
Chip Offset
15
AnalogAnalog
CDMA Paradigm Shift
Multiple Users on One FrequencyAnalog/TDMA Try to Prevent Multiple Users Analog/TDMA Try to Prevent Multiple Users InterfaceInterface
Channel is Defined by CodeAnalog Systems Defined Channels by Analog Systems Defined Channels by FrequencyFrequency
Traditional FDMA/TDMA are capacity-limited
Given N timeslots per frame and K Given N timeslots per frame and K frequency channels, maximum number of frequency channels, maximum number of users is KN;users is KN;To increase the number of users in the To increase the number of users in the system, frequency reuse is usedsystem, frequency reuse is used
Capacity Limit is SoftAllows Degrading Voice Quality to Allows Degrading Voice Quality to Temporarily Increase CapacityTemporarily Increase CapacityReduce Surrounding Cell Capacity to Reduce Surrounding Cell Capacity to Increase a CellIncrease a Cell’’s Capacitys Capacity
CDMA
16
CDMA Capacity Gains
ProcessingProcessingGainGain
AMPS = 1.5 MHz / 30 kHz = 50 Channels
Capacity = 50 Channels / 7 ( 1/7 Frequency Reuse )
AMPS = 7 Calls ( Using 1.5 MHz BW )
CDMA = 42 Calls ( Using 1.5 MHz BW )
(1,230,000) (1) (1)CDMA = ____________ X _____ X _____ X (0.67) (9,600) (5.01) (.40)
Capacity = _____________ X _____ X ____ X (Fr) (Data Rate) (S/N) (Vaf) (Chan BW) (1) (1)
17
CDMA makes use of Diversity
• Spatial DiversityMaking Use of Differences in Position
• Frequency DiversityMaking Use of Differences in Frequency
• Time DiversityMaking Use of Differences in Time
18
CDMA Spatial Diversity
• Diversity Reception:Multiple Antennas at Base Station
Each Antenna is Affected by Each Antenna is Affected by MultipathMultipath Differently Due to Their Differently Due to Their Different LocationDifferent LocationAllows Selection of the Signal Least Affected by Allows Selection of the Signal Least Affected by MultipathMultipathFadingFading
• If Diversity Antennas are Good, Why Not Use Base Stations as a Diversity Network?
Soft Handoff
19
Spatial Diversity During Soft Handoff
MTSO
Base Station 1
Land Link
Vocoder / Selector
Base Station 2
20
CDMA Frequency Diversity
• Combats Fading, Caused by Multipath• Fading Acts like Notch Filter to a Wide Spectrum
Signal• May Notch only Part of Signal
1.23 MHz BWAmplitude
Frequency
21
CDMA Time Diversity
• Rake Receiver to Find and Demodulate Multipath Signals
• Data is InterleavedSpreads Adjacent Data in time to Improve Error Correction Efficiency
• Convolutional EncodingAdds Error Correction and Detection
• Viterbi DecodingMost Likely Path Decoder for Convolutionaly Encoded Data
22
Why Interleaving Works
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
1 5 9 13
3 7 11 15
4 8 12 16
1 2 3 4
9 10 11 12
13 14 15 16
5 6 7 8
Original Data Frame
Interleaved Data Frame
Errors/Time
TX1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Errors/Time
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
RX
Errors/Time
TX1 5 9 13 2 6 10 14 3 7 11 15 4 8 12 16
Errors/Time
RX1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
2 6 10 14
23
The Rake Receiver
Amplitude
Frequency
Time
24
Rake Receiver Design
T0 T1 T4T3T2
W0 W1 W2 W3 W4
Antenna
Output
DelayTaps
TapWeights
+
25
Synchronization
• All Direct Sequence, Spread Spectrum Systems Should be Accurately Synchronized for Efficient searching
• Finding the Desired CodeBecomes Difficult without Synchronization
26
Power Control
Near-end Far-end Problem- 60dBm
- 30dBm
A
B
At the BS receiver, SNR for A reception = 30 dB, certifiedSNR for B reception = -30 dB, not certified
27
Acceptable SNR is at least 7 dB
For B, the signal needs 37 dB gain to meet the condition
What if we increase the processing gain from 21 dB to 37 dB?
Pgain = 10 log ( W / R )
R is fixed at 9600 bps, W can be increased
Is there another way to improve S/N?
In this case, W = 48 MHz not practical
Power Control
28
In this case, B is the Signal and A is the Noise
Both A and B are transmitting at constant power
Since A is near, it can be asked to transmit at low power
Since B is far, it can increase the power
This is Power Control !This is Power Control !Base Station will change power levels based on the Path loss.
Base Station will also command Mobile to increase or decrease power levels.
Power Control
29
• Maximum System Capacity is Achieved if:All Mobiles are Power Controlled to the Minimum Power for Acceptable Signal QualityAs a Result, all Mobiles are Received at About Equal Power at the Base Station Independent of Their Location
• Two Types of Control• Open Loop Power Control• Closed Loop Power Control
• Open & Closed Loop Power Control areAlways Both ActiveAlways Both Active
Reverse Link Power Control
30
Open Loop Power Control
• Assumes Loss is Similar on Forward and Reverse Paths
• Receive Power + Transmit Power = -73(-76dB for PCS Band
All Powers in dBm• Example:
For a Received Power of -85 dBm Transmit Power = (Transmit Power = (--73) 73) -- ((-- 85)85) Transmit Power = +12 Transmit Power = +12 dBmdBm
• Provides an Estimate of Reverse TX Power for Given Propagation Conditions
31
• Directed by Base Station• Updated Every 1.25 msec• Commands Mobile to Change TX
Power in +/- 1 dB Step Size• Fine Tunes Open Loop Power
Estimate• Power Control Bits are “Punctured”
over the Encoded Voice Data• Puncture Period is Two 19.2 kbps Symbol Periods = 104.2 usec
Closed Loop Power Control
32
CDMA Variable Rate Speech Coder
• DSP Analyzes 20 Millisecond Blocks of Speech for Activity• Selects Encoding Rate Based on Activity:aHigh Activity Full Data Rate Encoding (9600 bps)aSome Activity Half Data Rate Encoding (4800 bps)aLow Activity Quarter Data Rate Encoding (2400 bps)aNo Activity 1/8 Data Rate Encoding (1200 bps)
• How Does This Improve Capacity?Mobile Transmits in Bursts of 1.25 ms
• System Capacity Increases by 1/Voice Activity Factor
33
Mobile Power Bursting
• Each Frame is Divided into 16 Power Control Groups
• Each Power Control Group Contains 1536 Chips (represents 12 encoded voice bits)
• Average Power is Lowered 3 dB for Each Lower Data Rate
CDMA Frame = 20 ms Full Rate
Half Rate
Quarter Rate
Eighth Rate
34
The CDMA2000 evolution path is flexible and future-proof
• Voice
• Data up to 14.4 kbps
• Voice
• Data up to 115 kbps
• 2x increases in voice capacity
• Up to 307 kbps* packet data on a single (1.25 MHz) carrier
• First 3G system for any technology worldwide
• Optimized, very high-speed data (Phase 1)
• Up to 2.4 Mbps* packet data on a single (1.25 MHz) carrier
• Integrated voice and data (Phase 2); up to 4.8 Mbps
*downlink
From CDG
35
CDMA Protocol Stacks
IS -95 Rev 0Original System-never actually deployed
ARIB T53Japan CDMA
System CellularProtocol
IS -95 Rev ABackwards compatible with IS-95. First Deployed Protocol
TBS- 74Cellular Protocol that adds 14400 Channel Support
J-STD-008Not Backwards Compatible, PCS only Protocol
EIA/TIA-95 Rev BCombines TSB-74 & J-STD-008 for a Universal Protocol
EIA/TIA/IS-2000 Rev 0First release of IS-2000 standard(add QPCH)
EIA/TIA/IS-2000 Rev AAdd BCH,CCCH,CACH…new channel
EIA/TIA/IS-2000 Rev BAdd new functionality and support
EIA/TIA/IS-2000 Rev C(1x EV-DV)Segment channel between Voice and DataEIA/TIA/IS-856(1x EV-DO)
Optimized for packet data.
36
The architecture for CDMA2000
IS634
PSDN
MSC
HLR/AUCHLR/AUC
Laptops withCell Phones
CellPhones
Smartphonesand PDAs
BSCAAAAAAServerServer
PSTN
Internet
IWF
IP Router
CoreElements
CoreElements
From CDG
37
cdma2000 Key Standards
• EIA/TIA/IS-2000 rev. 0 Interoperability Standard for cdma2000 Spread Spectrum Systems
Defines channel coding, call processing procedures, protocol and other mobile / base procedures and RF requirements to ensure interoperability of equipment from multiple vendorsDefines how entire system works together in extreme detailRevision 0 was first release of standard.Revision A adds enhanced channels for paging, call set-up and call control.Revision B enhanced from the cdma2000 Release A specifications
38
TIA/EIA-95-B IS-2000 IS-2000-AF-Pilot F-Pilot F-PilotF-Sync F-Sync F-Sync
F-PCH F-PCH F-BCCHF-CCCH
F-QPCH optional F-QPCH optionalF-CACH
F-CPCCH
ForwardChannels
F-TrafficF-FCHF-SCH
F-DCCH optional
F-FCHF-SCH
F-DCCH optional
N/A R-Pilot R-PilotR-ACH R-ACH R-EACH or R-CCCHReverse
ChannelsR-Traffic
R-FCHR-SCH
R-DCCH optional
R-FCHR-SCH
R-DCCH optional
cdma2000 Standards Overview - IS-2000 Release 0 versus Revision A
39
Benefits of cdma2000
• Improved Performance and Capacity:About 2X Voice Capacity of TIA/EIA-95-BHandles a Wide Range of Data Rates:
Voice and Low Speed Data while DrivingVoice and Low Speed Data while DrivingUp to 384 kbps Packet or Circuit Data while MovingUp to 384 kbps Packet or Circuit Data while MovingUp to 2 Mbps Data Rates for Fixed InstallationsUp to 2 Mbps Data Rates for Fixed Installations
• Meets All IMT-2000 Requirements• Easy Upgrade for Service Providers Who Currently Operate
TIA/EIA-95 Systems
40
cdma
2000
Performance Enhancements
• Reverse Link Pilot for Each Mobile• True QPSK Modulation• Continuous Reverse Link Waveform• Improved Convolutional Encoding for 14.4
kbps Voice Channels• Fast Forward & Reverse Link Power Control• Supports Auxiliary Pilots for Beam Forming• Forward Link Transmit Diversity - OTD,
STS, Multi-Antenna
41
Reuse of TIA/EIA-95-B
• cdma2000 is Fully Backwards Compatible with TIA/EIA-95-B• Reused Aspects of TIA/EIA-95-B:
TIA/EIATIA/EIA--9595--B Air Interface (RC1, RC2)B Air Interface (RC1, RC2)ISIS--127 EVRC 8 kbps 127 EVRC 8 kbps VocoderVocoder and ISand IS--733 13 kbps 733 13 kbps VocoderVocoderAll Existing Service OptionsAll Existing Service OptionsISIS--637 SMS & IS637 SMS & IS--683 Over the Air Activation683 Over the Air ActivationISIS--98 and IS98 and IS--97 Minimum Performance Standards97 Minimum Performance StandardsCommon Broadcast Channels (Pilot, Sync ,Paging)Common Broadcast Channels (Pilot, Sync ,Paging)
• Allows cdma2000 to be Deployed Sooner
42
Terms and Definitions
• ChipIs the period of a data bit at the final spreading rateIs the period of a data bit at the final spreading rate
• SR - Spreading RateDefines the final spreading rate in terms of 1.2288 Mcps(SR1). Defines the final spreading rate in terms of 1.2288 Mcps(SR1). So a 3.6864 So a 3.6864 McpsMcps system is called a SR3 system.system is called a SR3 system.
• RC - Radio ConfigurationDefines the physical channel configuration based upon a base Defines the physical channel configuration based upon a base channel data rate.channel data rate.RCsRCs contain rates derived from their base rate. For example, contain rates derived from their base rate. For example, RC3 is based on 9.6 kbps and includes 1.5, 2.7, 4.8, 9.6, 19.2, RC3 is based on 9.6 kbps and includes 1.5, 2.7, 4.8, 9.6, 19.2, 38.4, 76.8, 153.6, and 307.200 kbps.38.4, 76.8, 153.6, and 307.200 kbps.RCsRCs are coupled to specific Spreading Ratesare coupled to specific Spreading Rates
43
IS-2000 SR1 (aka 1xRTT)
• Is an Improved TIA/EIA-95-B Narrowband System• Occupies the Same 1.23 MHz Bandwidth as TIA/EIA-95-B
Forward Link:Adds Fast Power ControlAdds Fast Power ControlQuick Paging Channel to Improve Standby TimeQuick Paging Channel to Improve Standby TimeUses QPSK Modulation Rather than Dual BPSK to:Uses QPSK Modulation Rather than Dual BPSK to:– Use 3/8 Rate Convolutional Encoder instead of 3/4 for 14.4 Service
(improves error correction) – 128 Walsh Codes to Handle More Soft Handoffs for 9.6 service
Reverse Link:Uses Pilot Aided BPSK to Allow Coherent DemodulationUses Pilot Aided BPSK to Allow Coherent DemodulationUses 1/4 Rate Uses 1/4 Rate ConvolutionalConvolutional Encoder Instead of 1/2 or 1/3Encoder Instead of 1/2 or 1/3Uses HPSK SpreadingUses HPSK Spreading
• Doubles System Voice Capacity
44
SR1 Forward Radio Configurations
• Radio Configuration 1 - RequiredBackwards compatible mode with TIA/EIABackwards compatible mode with TIA/EIA--9595--BBBased on 9,600 bps Traffic(RS1)Based on 9,600 bps Traffic(RS1)
• Radio Configuration 2Backwards compatible mode with TIA/EIABackwards compatible mode with TIA/EIA--9595--BBBased on 14,400 bps Traffic(RS2)Based on 14,400 bps Traffic(RS2)
• Radio Configurations 3, 4, and 5All use new cdma2000 coding for improved capacityAll use new cdma2000 coding for improved capacityRC3 is based on 9,600 bps and goes up to 153,600 bpsRC3 is based on 9,600 bps and goes up to 153,600 bpsRC4 is based on 9,600 bps and goes up to 307,200 bpsRC4 is based on 9,600 bps and goes up to 307,200 bpsRC5 is based on 14,400 bps and goes up to 230,400 bpsRC5 is based on 14,400 bps and goes up to 230,400 bps
45
SR1 Forward Channels
• F-Pilot (Using TIA/EIA-95-B Coding)• F-Sync (Using TIA/EIA-95-B Coding)• Up to 7 F-Paging (Using TIA/EIA-95-B Coding) • IS-2000 Rev.0
0 to 3 F-QPCH (Quick Paging Channel)
• IS-2000 Rev.A/B0 or 8 F-BCH (Broadcast Channel)0 to 4 F-CPCCH (Common Power Control Channel)0 to 7 F-CACH (Common Assignment Channel)0 to 7 F-CCCH (Common Control Channels)
• Many F-Traffic Channels, Each Consisting of:0 or 1 F0 or 1 F--DCCH (Dedicated Control Channels)DCCH (Dedicated Control Channels)1 F1 F--FCH (Fundamental Channel)FCH (Fundamental Channel)0 to 7 F0 to 7 F--SCCH (Supplemental Code Channels for RC1 & RC2)SCCH (Supplemental Code Channels for RC1 & RC2)0 to 2 F0 to 2 F--SCH (Supplemental Channel for RC3, 4, 5)SCH (Supplemental Channel for RC3, 4, 5)
46
Base Station Variable Rate Vocoder
• Base Stations Do Not Pulse TX Channels• How Does the Base Station Handle Variable
Rate Vocoding?Repeats Data Bits When Transmitting at Reduced RatesRepeating Data Adds 3 dB Coding GainLowers the TX Power 3dB for Each Lower Rate
47
Walsh CodeGenerator
Forward Link Traffic Channel Physical Layer (RC1,RC2)
1/2Rate
3/4Rate
P.C.Mux
VocodedSpeechData
20 msecblocks
ConvolutionalEncoder Interleaver
Long CodeScrambling
PowerControl
Puncturing800 bps Walsh
Coder9.6kbps
14.4kbps
19.2kbps
19.2kbps
Long Code
19.2kbps
19.2kbps
19.2kbps
19.2kbps
1.2288 Mbps
1.2288 Mbps
1.2288Mbps
1.2288Mbps
Short Code Scrambler
800bps
FIR
FIR
I
Q
I Short Code
Q Short Code
48
Forward FCH Physical Layer RC3 (9.6 kbps)
OptionalCan be Carried by F-DCCH
8.6 kbps
1228.8 kbps
Long CodeDecimator
Interleaver
38.4 ksps
1/4 Rate Conv.Encoder
38.4 ksps
9.6 kbps
Long CodeGenerator
38.4 kbps
PowerControlPuncture
Walsh 64Generator
1228.8 kcps
1228.8 kcps
1228.8 kbps
1228.8kbps
Q
I
S -P
800 bps
PCUser LongCode Mask
Q
I
PCDec
1228.8 kcps
Q Short Code
I
Q
1228.8 kcps
ComplexScrambling
Q
I
FIR
FIRI Short Code
OrthogonalSpreading
1228.8 kcps
1228.8 kcps+
+
+
-
38.4 ksps
19.2 ksps
19.2 ksps
P.C. Bits
Decimate by Walsh Length/2
Gain
Gain
PunctureTiming
Full RateData Bits
Add CRC andTail Bits
800 bps
49
CDMA Vocoders
• Vocoders Convert Voice to/from Analog Using Data Compression
• There are Three CDMA Vocoders:IS-96A Variable Rate (8 kbps maximum)CDG Variable Rate (13 kbps maximum)EVRC Variable Rate (improved 8 kbps)
• Each has Different Voice Quality:• IS-96A - moderate quality• EVRC - near toll quality• CDG - toll quality
50
15
24 bits in a ms frame
39
79
171 266
124
54
201200 bpsFrame
8
Mixed Mode Bit Information Bits1-bitReserved
8
8
88
12 12 8
10 8
6
88
8
Mixed Mode Bit
Mixed Mode Bit
Mixed Mode Bit
Information Bits
Information Bits
Information Bits
2400 bpsFrame
9600 bpsFrame
4800 bpsFrame
192 bits in a ms frame
96 bits in a ms frame
48 bits in a ms frame
1800 bpsFrame
3600 bpsFrame
7200 bpsFrame
14400 bpsFrame
288 bits in a ms frame
144 bits in a ms frame
72 bits in a ms frame
36 bits in a ms frame
1-bitReserved
1-bitReserved
1-bitReserved
MixedMode Bit
MixedMode Bit
MixedMode Bit
MixedMode Bit
Encoder Tail Bits
CRC
CRC
Encoder Tail Bits
Encoder Tail Bits
Encoder Tail Bits
Information Bits
Information Bits
Information Bits
Information BitsEncoder Tail Bits
Encoder Tail Bits
Encoder Tail Bits
Encoder Tail Bits
CRC
CRC CRC
CRC
CDMA Frame Formats
51
Forward Error Protection
• Uses Half-Rate Convolutional Encoder• Outputs Two Bits of Encoded Data for Every Input Bit
Data Out9600 bps
Data Out9600 bps
D DDDD D D D
+
+
Data In9600 bps
52
14.4 Traffic Channel Forward Link Modifications
• Replaces 8 kbps Vocoder with a 13 kbps Vocoder(both Variable Rate)
• Effects:Provides Toll Quality SpeechUses a 3/4 Rate EncoderReduces Processing Gain 1.76 dBResults in Reduced Capacity or Smaller Cell Sizes
3/4rate
VocodedSpeechData
ConvolutionalEncoder
20 msecblocks
14.4kbps
19.2kbps
53
• 384 symbols are sequentially written in an input array• Interleaved symbols are then read from the output array
19.2 ksps9.6 ksps4.8 ksps2.4 ksps
SymbolRepetition
19.2 ksps
384 Symbols
20 ms
Block Interleaver
Input Array / output
Array
16 x 24 Array
Interleaved Output
16
24
Interleaver
• Process of permuting a sequence of symbols to achieve time diversity
• CDMA uses block interleaving with 20 ms blocks
54
CDMA System Time
• How Does CDMA Achieve Synchronization for Efficient searching?
Use GPS Satellite System• Base Stations Use GPS Time
via Satellite Receivers as a Common Time Reference
• GPS Clock Drives the Long Code Generator
112
2
3
4567
8
9
1011
55
Modulo-2 Addition
Long Code Output
Long Code Generator
1
User AssignedLong Code Mask
42 bits
24 342 41 5
Long Code Generation
56
Long Code Generation
Modulo-2 Addition
Long Code Output
34 12
User AssignedLong Code Mask
42 bits4142 5
Long Code Generator(Driven by System Time)
1100011000 Permuted ESN41 32 31 0
Long Code Mask
57
Long Code Scrambling
• User’s Long Code Mask is Applied to the Long Code
• Masked Long Code is Decimated Down to 19.2 kbps
• Decimated Long Code is XOR’ed with Voice Data Bits
• Scrambles the Data to Provide Voice Security
Encoded Voice Data
Long Code Generator
Long Code Decimator
XOR
1.2288 Mbps
19.2 kbps
19.2 kbps
19.2 kbps
58
19.2 kbps
Closed Loop Power Control Puncturing
• Long Code is Decimated Down to 800 bps
• Decimated Long Code Controls the Puncture Location
• Power Control Bits Replace Voice Data
• Voice Data is Recovered by the Mobile’s Viterbi Decoder
Long CodeScrambledVoice Data
Long CodeDecimatedData
Closed LoopPowerControl Bits
P. C.Mux
Long CodeDecimator
800 bps
800 bps
19.2 kbps
19.2 kbps
59
Power Control Bit Puncturing
19.2 ksps: 384 symbols / 20ms frameEach 20ms frame is divided into 16 power control group (1.25 ms each)24 modulation symbols in each power control group
Long Code DecimatedData Decimator19.2 ksps
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
4 symbols = 16 combinations
20ms
1.25ms
If [20,21,22,23]=[1,1,0,1],then puncture bit 11,12
60
PayloadData Bits
1228.8 kbpsLong CodeDecimator
Interleaver
1/2 Rate
ConvolutionalEncoder
307.2 ksps
Channel Coder
Add CRC andTail Bits
153.6 kbps
Long CodeGenerator
User LongCode Mask
Decimate by Walsh Length/2
307.2 ksps
307.2 ksps
307.2 ksps
Gain Walsh 8Generator
1228.8 kcps
1228.8 kcps
1228.8 kbps
1228.8kbps
Q
I
S -P
Q
I1228.8 kcps
Q Short Code
I
Q
1228.8 kcps
ComplexScrambling
FIR
FIRI Short Code
OrthogonalSpreading
1228.8 kcps
1228.8 kcps
+
+
+
-
153.6 ksps
153.6 ksps
152.4 kbps
SR1, RC4 (152.4 kbps) F-SCH
61
Walsh Codes
W = 0 00 1
W = 0
0 0 0 00 1 0 10 0 1 10 1 1 0
W =
1
2
4
=
nn
nnn WW
WWW2
62
2 Match - 2 don’t = 0
Checking for Orthogonality
W =4
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 0 1 1
Y Y N N
Cross Correlation=
N agreements- N disagreements
N total_number_of_digits
63
SF=16SF=2 SF=4 SF=81 1 1 1 1 1 1 1
1 1 1 1 -1 -1 -1 -1
1 1 -1 -1
1 1 1 1
1 1
1 -1
1 -1 1 -1
1 -1 -1 1
1
1 -1 1 -1 1 -1 1 -1
1 -1 1 -1 -1 1 -1 1
1 -1 -1 1 1 -1 -1 1
1 -1 -1 1 -1 1 1 -1
1 1 -1 -1 -1 -1 1 1
1 1 -1 -1 1 1 -1 -1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 -1 -1 -1 -1 -1 -1 -1 -1
1 1 1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -11 1 1 1 -1 -1 -1 -1 -1 -1 -1 -1 1 1 1 1
1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -11 1 -1 -1 1 1 -1 -1 -1 -1 1 1 -1 -1 1 1
1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -1 1 11 1 -1 -1 -1 -1 1 1 -1 -1 1 1 1 1 -1 -1
1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -11 -1 1 -1 1 -1 1 -1 -1 1 -1 1 -1 1 -1 1
1 -1 1 -1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 11 -1 1 -1 -1 1 -1 1 -1 1 -1 1 1 -1 1 -1
1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 11 -1 -1 1 1 -1 -1 1 -1 1 1 -1 -1 1 1 -1
1 -1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 1 1 -11 -1 -1 1 -1 1 1 -1 -1 1 1 -1 1 -1 -1 1
Effects of Using Variable Length Walsh Codes for Spreading
• Using Shorter Walsh Codes Precludes Using all Longer Codes Derived from the Original
• Shorter Codes on a Branch map into Longer Codes
64
Walsh Code Spreading
EncodedVoice Data
Walsh CodeGenerator
19.2 kbps
1.2288 Mbps
1.2288 Mbps
What is theSpreading RateIncrease ?
65
Why Spread Again with the Short Sequence
• Provides a Cover to Hide the 64 Walsh Codes
• Each Base Station is Assigned a Time Offset in its Short Sequences
• Time Offsets Allow Mobiles to Distinguish Between Adjacent Cells
• Also Allows Reuse of All Walsh Codes in Each Cell
Walsh CodedData at1.2288 Mbps
1.2288 Mbps
1.2288 Mbps I Channel ShortSequence CodeGenerator
Q Channel ShortSequence CodeGenerator
To I/QModulator
66
Multi-Layer Code Assignment
Walsh Code layer (spreading code)
Full codeset per cell
W64,1
W64,2
W64,0
Cells A/Sector A
W64,1
W64,2
W64,0
Cells B/Sector B
PN 0
PN 1
ConvolutionalEncoder
Long code
Walsh Code
Short Code
CDMA as an OnionCDMA as an Onion
67
Short Code (PN) Generation
PN sequence codes are generated using 15-bit shift registersPN sequence pattern repeats every 26.666 ms75 PN sequences repetition occur every 2 secondsOn every even second clock, MS will get PN sequence initial state
Jan 6, 1980 00:00:00
1, 0, 0, 0.............. 0R1,R2,R3,R4..........R15
( initial state of 15 registers )PN Code Combinations: 215 = 32768Clock Rate = 1.2288 McpsReturn of Initial State = 26.666 ms
32768
32768
1
274
7532768
2 sec26.666ms
68
PN Offsets
• Each BS scrambles PN sequence with data by some time offset
• Time offsets are in intervals of 64 clock chips (52.08 us) from even second clock
• 512 unique offsets are created (32768/64 = 512)
• Each BS is allotted an offset for PN sequence scrambling
PN 0
PN 120
PN 237
PN 511
PN 489
69
Short Code Correlation
• Short Codes are Designed to Have:
Strong Auto-Correlation at Zero Time OffsetWeak Auto-Correlation at Other OffsetsGood Auto-Correlation in Very Poor Signal-to-Noise Ratio Environments
• Allows Fast Acquisition in Real World Environment
Auto-Correlation VersusTime Offset With 17 dB Noise Added
0 10 205 15 25 30Chip Offset
70
Convert to I/Q& PNSpreading
FIR LP Filter &D/A Conversion
I Data
Q Data
1228.8 kbps
Walsh Code 0
Pilot Channel All 0’s
Convert to I/Q& PNSpreading
FIR LP Filter &D/A Conversion
I Data
Q Data
1228.8 kbps
Walsh Code 32
Sync Channel 4.8 kbps
Convert to I/Q& PNSpreading
FIR LP Filter &D/A Conversion
I Data
Q Data
1228.8 kbps
Walsh Codes 1 to 7
Paging Channels1 up to 7 Channels
19.2 kbps
Convert to I/Q& PNSpreading
FIR LP Filter &D/A Conversion
I Data
Q Data
1228.8 kbps
Walsh Codes 8-31,33-63
Traffic Channels1 up to 55 Channels
19.2 kbps
I
Q
Forward Link Channel Format
Σ
Σ
71
Walsh Coding Example
W2 =0 0 - User A0 1 - User B
-1
-2
+1+2
-1
+1Channel AWalsh EncodedVoice Data
+1
-1
Channel AVoice Data
For a 1 InputUse Code 11
+1
-1
For a 0 InputUse Code 00
User A User BFor a 0 InputUse Code 01
For a 1 InputUse Code 10
Channel BVoice Data
Channel BWalsh EncodedVoice Data
Sum of A & BWalsh EncodedData Streams
0 0
1 1
0 0 1 1 0 0 0 0
+1
-1
+1
-10 1
1 0
-1
+1
1 0 0 1 0 1 1 0
+0
+1
1 0 0 1
+1
01 0 0 1
72
Walsh Decoding Example
Correlation Coefficient
f i (t) r f j (t) dtz i j = 1T
+1
01 0 0 1
+1
-1
+2
-2
Original User B Voice Data
User A & B Walsh Data
Multiply Summed Data with Desired Walsh Code
+1
01 0 0 1
+1
-1
+2
-2
Original User A Voice Data
User A & B Walsh Data
Multiply Summed Data with Desired Walsh Code
+1
-1
+2
-2
X
+1
-1 1 1
+1
-1
+2
-2
∫ -1 +1
-1
+2
-2
+1
-11 0
1+1
-1
+2
-2
= = = =+
∫0
T
∫
73
What if Walsh Codes are Not Time Aligned ?
Channel BWalsh EncodedVoice Data -1
+1
1 0 0 1 0 1 1 0-1
+1Channel AWalsh EncodedVoice Data
0 0 1 1 0 0 0 0
-1
-2
+1Sum of A & BWalsh EncodedData Streams
Original Data Was0 (-1), We HaveInterference Now!
Multiply Summed Data with Desired Walsh Code
+1
-1
+2
-2
+1
-1 1 1
+1
-1
+2
-2
-0.75
Original Time Delayed
+
X = =∫
74
Pilot Channel Physical Layer
WalshModulator
1.2288 Mbps
1.2288 Mbps
1.2288Mbps
1.2288Mbps
Short Code Scrambler
FIR
FIR
I
Q
Walsh CodeGenerator Q Short Code
I Short Code
All 0Inputs
19.2kbps
WalshCode 0
• Uses Walsh Code 0:All 64 bits are 0
• All Data into Walsh Modulator is 0
• Output of Walsh Modulator is therefore all 0’s
• Pilot Channel is just the Short Codes
75
1/2Rate 2x
ConvolutionalEncoder Interleaver Walsh
32Coder
1.2kbps
2.4kbps
4.8kbps
1.2288 Mbps
1.2288 Mbps
1.2288Mbps
1.2288Mbps
Short Code Scrambler
FIR
FIR
I
Q
Sync Channel Physical Layer
SyncChannelMessageData
SymbolRepetition
4.8kbps
Walsh CodeGenerator Q Short Code
I Short Code
76
Paging Channel Physical Layer
Paging ChannelLong Code
1/2Rate
ConvolutionalEncoder Interleaver
4.8kbps
9.6kbps
19.2kbps
PagingChannelMessageData
2x
SymbolRepetition
19.2kbps
Walsh1 to 7Coder
1.2288 Mbps
1.2288 Mbps
1.2288Mbps
1.2288Mbps
Short Code Scrambler
I
Q
Walsh CodeGenerator QShort Code
Long CodeScrambling
19.2kbps
19.2kbps
FIR
I Short Code
FIR
77
SR1 Reverse Radio Configurations
• Radio Configuration 1 - RequiredBackwards compatible mode with TIA/EIABackwards compatible mode with TIA/EIA--9595--BBBased on 9,600 bps TrafficBased on 9,600 bps Traffic
• Radio Configuration 2Backwards compatible mode with TIA/EIABackwards compatible mode with TIA/EIA--9595--BBBased on 14,400 bps TrafficBased on 14,400 bps Traffic
• Radio Configurations 3 and 4All use new ISAll use new IS--2000 coding for improved capacity2000 coding for improved capacityRC3 is based on 9,600 bps and goes up to 307,200 bpsRC3 is based on 9,600 bps and goes up to 307,200 bpsRC4 is based on 14,400 bps and goes up to 230,400 bpsRC4 is based on 14,400 bps and goes up to 230,400 bps
78
SR1 Reverse Channels
• Each Mobile Transmits Several Channels:
1 R1 R--Pilot Pilot (Reverse Pilot)Includes Power Control SubIncludes Power Control Sub--ChannelChannel
1 R1 R--ACH or RACH or R--EACH EACH (Access or Enhanced Access Channel)Used to Initiate CallsUsed to Initiate Calls
0 or 1 R0 or 1 R--CCCH CCCH (Common Control Channel)Used to Initiate Calls in the Reservation Access ModeUsed to Initiate Calls in the Reservation Access Mode
0 or 1 R0 or 1 R--DCCHDCCH (Dedicated Control Channel)Provides Signaling while a Traffic Channel is ActiveProvides Signaling while a Traffic Channel is Active
0 or 1 R0 or 1 R--FCHFCH (Reverse Fundamental Channel)Primary Channel, usually VoicePrimary Channel, usually Voice
0 to 2 R0 to 2 R--SCHsSCHs (Reverse Supplemental Channels)Carries High Speed DataCarries High Speed Data
79
R-FCH Coding for SR1(RC1,RC2)
1/2Rate
VocodedSpeechData
20 msecblocks
ConvolutionalEncoder
Interleaver
9.6kbps
14.4kbps
28.8kbps
28.8kbps
28.8kbps
1.2288 Mbps
1.2288 Mbps
Short Code Scrambler
I
Q
1/3Rate
Long Code
64-aryModulator
1 of 64Walsh Codes
WalshCode 2
WalshCode 63
WalshCode 62
WalshCode 61
WalshCode 1
WalshCode 0
Long CodeModulator
307.2kbps
1.2288Mbps 1.2288 Mbps
Q Short Code
FIR
I Short Code
FIRt/ 21/2 Chip Delay
80
Reverse Error Protection
• Uses Third-Rate Convolutional Encoder• Outputs Three Bits for Every Input Bit
Data Out9600 bps
D DDDD D D D
+
+Data Out9600 bps
+
Data In9600kbps
Data Out9600 bps
81
14.4 Traffic Channel Reverse Link Modifications• Replaces 8 kbps Vocoder with
a 13 kbps Vocoder (both Variable Rate)
• Effects:Provides Toll Quality SpeechUses a 1/2 Rate EncoderReduces Processing Gain 1.76 dBResults in Reduced Capacity or Smaller Cell Sizes
1/2Rate
VocodedSpeechData
20 msecblocks
ConvolutionalEncoder
14.4kbps
28.8kbps
82
64-ary Modulation
• Every 6 Encoded Voice Data Bits Points to one of the 64 Walsh Codes
• Spreads Data from 28.8 kbps to 307.2 kbps
(28.8 kbps * 64 bits) / 6 bits = 307.2 kbps)
• Is Not the Channelization for the Reverse Link
307.2kbps
28.8kbps>
WalshCode 2WalshCode 1WalshCode 0
WalshCode 63WalshCode 62WalshCode 61
83
Why Aren’t Walsh Codes Used for Reverse Channelization ?• All Walsh Codes Arrive
Together in Time to All Mobiles From the Base Station
• However, Transmissions from Mobiles DO NOT Arrive at the Same Time at the Base Station
84
Reverse Channel Long Code Spreading
• Long Code Spreading Provides Unique Mobile Channelization
• Mobiles are Uncorrelated but not Orthogonal with Each Other
Long CodeGenerator
WalshModulatedVoice Data
XOR
307.2 kbps 1.2288 kbps
1.2288 kbps
85
Data Burst Randomizer
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
576 code symbols (28.8ksps)96 modulation symbols (576 / 6)
20 ms =
1.25 ms =36 code symbols6 modulation symbols
12 13 14 15
b0 b1 b2 b3 b4 b5 b6 b7 b8 b9 b10 b11 b12 b13Long Code Bits used for spreading PCG14
Previous Frame
AlgorithmAt 4800 bps rate,Transmission should occur on the PCG's numbered:
b0, 2 + b1, 4 + b2, 6 + b3, 8 + b4,10 + b5, 12 + b6, 14 + b70 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 (Example)
(50% Gated-On, 50% Gated-Off)
86
Data Burst Randomizer
AlgorithmAt 2400 bps rate ,Transmission should occur on the PCG's numbered:
b0 if b8 = 0, or 2 + b1 if b8 = 1 (i.e. 1 out of PCG 0...3)4 + b2 if b9 = 0, or 6 + b3 if b9 = 1 (i.e. 1 out of PCG 4...7)8 + b4 if b10 = 0, or 10 + b5 if b10 = 1 (i.e. 1 out of PCG 8...11)12+b6 if b11 = 0, or 14 + b7 if b11 = 1 (i.e. 1 out of PCG 12..15)
(Example)( 25% Gated-On, 25% Gated-Off )
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
At 1200 bps rate ,Transmission should occur on the PCG's numbered:
b0 if (b8 = 0 and b12=0), or 2 + b1 if (b8 = 1 and b12=1)or 4 + b2 if (b9 = 0 and b12=0), or 6 + b3 if (b9 = 1 and b12=1) (i.e. 1 out of PCG 0...7)
8 + b4 if (b10 = 0 and b13=0), or 10 + b5 if (b10 = 1 and b13=1)or 12 + b6 if (b11 = 0 and b13=0), or 14 + b7 if (b11 = 1 and b13=1) (i.e. 1 out of PCG 8..15)
(Example)(12.5% Gated-On, 12.5% Gated-Off)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
87
Gated-On and Gated-Off Power
7 us 7 us
20 dB or tothe noisefloor (-60dBm)
3 dB
1.247 ms
Mean output of theensemble average
Ensemble average: Average of power control groups, all with the same output power
88
Reverse Channel Short Sequence Spreading
• Same PN Short Codes Are Used by Mobiles
• Short Sequence spreading Aids Base Station Signal Acquisition
• Extra 1/2 Chip Delay is Inserted into Q Path to Produce OQPSK Modulation to Simplify Power Amplifier Design
1.2288 Mbps
Short Code Scrambler
I
Q
1.2288 Mbps
I Short Code
FIR
I Short Code
FIRt/ 21/2 Chip Delay
1.2288Mbps
89
OQPSK Modulation
• QPSK Makes one Symbol Change Every Period
• OQPSK Makes two Symbol Changes Every Period if Q Data Changes
• Example Symbol Pattern is:- 00,10,01,11
I
Q
n
n n
n00 01
10 11
I
Q
n
n n
n00 01
10 11
90
CDMA Modulation Formats
Filtered Offset QPSKFiltered QPSK
I I
QQMobile Station TX
Base Station Pilot Channel TX
91
MUX
Pilot Data
PowerControl Bits
To I ChannelSummer
One Power Control Group
Pilot PilotPilot PC Bits
312.5 us 312.5 us 312.5 us 312.5 us
1.25 ms
Reverse Pilot/Power Control Multiplexing(RC3,4)
• There are 16 Power Control Groups per 20 ms Frame• Each Power Control Group is Split into 4 Sub-Groups• 1 Power Control Bit is Sent per Power Control Group• Pilot and Power Control are Multiplexed Together
92
R-FCHData Bits
8.6 kbps
Walsh CodeGenerator
1 Frame1/4 Rate
ConvolutionalEncoder
38.4 ksps
Channel Coder
Add CRC andTail Bits
9.6 kbps
Interleaver
1,1, 1, 1,-1, -1, -1, -1, 1,1, 1, 1,-1, -1, -1, -1
R-FCH Coding for a 20 ms FrameOrthogonalSpreading
SpreadFactor = 16
2 Reps
SymbolRepeat
38.4 ksps 76.8 ksps 1228.8 kcps
SR1, RC3 R-FCH Coding(RC3,RC4)
• R-FCH Carries Voice Information• Uses a 20 ms Frames Length• Using ¼ rate convolutional coding
93
1,1,1,1,1,1,1,1,-1,-1,-1,-1,-1,-1,-1,-1
I ChannelShort CodeGenerator
User Long Code Mask
ComplexScrambling
Q
I+
+
+
-
R-DCCH
R-Pilot +PowerControl
R-SCH 1orR-EACH orR-CCCH
R-FCH
Walsh 16Generator
1,1, 1, 1 -1,-1, -1, -1, 1, 1, 1, 1, -1, -1, -1, -1
Walsh 2/4/8Generator
1,-1 or 1 -1 1,-1, or 1,1,-1,-1,1,1,-1,-1
Walsh 16Generator
1228.8 kcps
R-SCH 2
Walsh 4/8Generator
1, 1, -1, -1 or 1, 1, -1, -1, -1, -1, 1, 1
Walsh 2Generator
1,-1
GainScale
GainScale
GainScale
GainScale
Deciby 21228.8 kcps
1228.8 kcps
1228.8 kcps
1228.8 kcps
1228.8 kcps
1228.8 kcps
1228.8 kcps
1228.8 kcps
Q ChannelShort CodeGenerator
1228.8 kcps
1-ChipDelay
Long Code Generator
1,1,1,1,-1,-1,-1,-1 forR-EACH or R-CCCH
SR1 Reverse Channel Spreading(RC3,RC4)
94
Channelization Summary
Function
9.6 kbpsConvolutional Encoder
14.4 kbpsConvolutional Encoder
Walsh Coding
Long CodeSpreading
Short CodeSpreading
Forward Link(Base to Mobile)
1/2 Rate(9600 in 19200 out)
3/4 Rate(14400 in 19200 out)
Channelization
Voice Privacy
Base StationIdentification
Reverse Link(Mobile to Base)
1/3 Rate(9600 in 28800 out)
1/2 Rate(14400 in 28800 out)
64-aryModulation
Channelization
Aid Base StationSearching
95
CDMA Multiplex Sublayer
Layer 1Physical Layer
Channel Data - 9600 bps or 14400 bps
Multiplex SublayerTraffic Channel
Layer 2Link Layer
Paging & AccessChannels
Layer 2Primary Traffic
Layer 2Signaling
Layer 3Call Processing & Control
96
Station Class Mark (SCM)
Extended SCMIndicator
7 Band Class 0 0XXXXXXXBand Class 1 1XXXXXXX
Dual Mode 6 CDMA Only X0 XXXXXX Dual Mode X 1XXXXXX
Slotted Class 5 Non-Slotted XX0XXXXXSlotted XX1XXXXX
IS- 54 Power Class 4 Always 0 XXX0XXXX
25 MHz Bandwidth 3 Always 1 XXXX1XXX
Transmission 2 Continous XXXXX0XXDiscontinous XXXXX1XX
Power Class for BandClass "0" AnalogOperation( For CDMA only "00")
1- 0 Class I XXXXXX00Class II XXXXXX01Class III XXXXXX10Reserved XXXXXX11
Function Bit(s) Setting
97
Ten Minutes in the Life of a CDMA Mobile Phone• Turn-on
System Access• Travel
Idle State Hand-Off• Initiate Call• System Access• Continue Travel
Initiate Soft HandoffTerminate Soft Handoff
• End Call
98
CDMA Turn On Process
• Find All Receivable Pilot SignalsChoose Strongest One
• Establish Frequency and PN Time Reference (Base Station I.D.)
• Demodulate Sync Channel• Establish System Time• Determine Paging Channel Long Code
Mask
99
Sync Channel Message
• Contains the Following Data:Base Station Protocol RevisionMin Protocol Revision SupportedSID, NID of Cellular SystemPilot PN Offset of Base StationLong Code StateSystem TimeLeap Seconds From Start of System TimeLocal Time Offset from System Time Daylight Savings Time FlagPaging Channel Data RateChannel Number
SYNC
100
Read the Paging Channel
• Demodulate the Paging Channel:
Use Long Code Mask Derived from the Pilot PN Offset Given in Sync Channel Message
• Decode Messages• Register, if Required by Base
Station• Monitor Paging Channel
Paging
101
CDMA Idle State Handoff
• No Call In Progress• Mobile Listens to New Cell• Move Registration Location if
Entering a New Zone
102
Access Procedures
• Controlled by BS by broadcasting Access Parameters Message on the paging channel
• Access attempt is the process of sending one message and receiving (or failing to receive) an ACK for that message= groups of access probe sequence
• Access probe sequence = groups of access probes• Access probe = each transmission in an access attempt
103
Access Probe
Access Channel Message 40 - 880 bits
Paddingas reqd
Frame Body88 bits
T8
Frame Body88 bits
T8
……
Access Channel Message Capsule
Access Chan Frame
96 b/20ms
Access Chan Frame
96 b/20ms
Access Chan Frame
96 b/20ms
Access Chan Frame
96 b/20ms
Access Chan Frame
96 b/20ms
Access Chan Frame
96 b/20ms
Access Probe (or Access Channel Slot)( 4 + PAM_SZ + MAX_CAP_SZ) x 20ms [ Max value = 26 frames ]
Preamble(1 + PAM_SZ) x 20ms
[ max = 16 frames ]
Access Channel Message Capsule(3 + MAX_CAP_SZ) x 20 ms
[ Max = 10 frames ]
Preamble96 bits “0”s
Preamble96 bits “0”s
PAM_SZ = No. of preamble framesMAX_CAP_SZ = No. of message capsule frames
104
Access Probe Sequence
Access Probe Sequence
AccessProbe 1
AccessProbe 2
AccessProbe 3
AccessProbe n
TA TA TART RT RT
Preamble + Access Message CapsuleMax = 26 frames
RN RN RN RN
IP
P1
P2
P3
IP = Open Loop Power + NOM_PWR + INIT_PWRwhere Open Loop Power = -( Received Power ) - 73
105
Access Attempt
RS : Backoff delay, which is random value between 0 to BKOFF slots
Process for Response MessagesProcess for Response Messages
message ready for transmission
Access Probe
Sequence
Access Probe
Sequence
Access Probe
Sequence
Access Probe
Sequence
Access AttemptMAX_RSP_SEQ
RS RS RS
106
Access Attempt
PD: (Persistence Delay) resulted from a pseudo-random test by MS; the first access probe of the sequence begins in the slot only if the test passes within that slotThe test result depends on the ESN, reason for attempt (call origination, register, etc.) and the access overload class of the MS, and a PSSIST value broadcasted by BS for that access class. If the PSSIST is all “1”s for some access class, the test for that access class will always fail
Process for Request MessagesProcess for Request Messages
message ready for transmission
Access Probe
Sequence
Access Probe
Sequence
Access Probe
Sequence
Access Probe
Sequence
Access AttemptMAX_REQ_SEQ
RS PD RS PDRS PDPD
107
Access Channel Messages
Registration Message - for registration as well as Global Challeng Authentication Process
Order Message - for transmission of order messages (e.g., BS challenge order, SSD update confirmation, MS acknowledgement order, etc.)
Data Burst Message - to get a trigger from the user to send a message to BS (information message like SMS)
Origination Message-MS informationPage Response messageAuthentication Challenge Response Message Status Response Message - response to BS status request
order which may include MS terminal information, station class mark, service option supported, multiplex option support, IMSI, ESN, etc.
108
CDMA Call Initiation
• Dial Numbers, Then Press Send• Mobile Transmits on a Special Channel Called the
Access Channel• The Access Probe Uses a Long Code Mask
Based On:bAccess & Paging Channel NumbersbBase Station IDbPilot PN Offset
109
CDMA Call Completion
• Base Answers Access Probe using the Channel Assignment Message
• Mobile Goes to A Traffic Channel Based on the Channel Assignment Message Information
• Base Station Begins to Transmit and Receive Traffic Channel
110
CDMA Soft Handoff Initiation
• Mobile Finds Second Pilot of Sufficient Power (exceeds T_add Threshold)
• Mobile Sends Pilot Strength Message to First Base Station• Base Station Notifies MTSO• MTSO Requests New Walsh Assignment from Second Base
Station• If Available, New Walsh Channel Info is Relayed to First
Base Station
111
Hard, Soft, and Softer Handoffs
• Hard Handoff“Break before make.”
• Soft Handoff“Make before break.”MS communicates with more than one BS at a time.Improves reception on cell boundaries.MS will receive different power control from the two BSs.
• Softer HandoffMS communicates with more than one sector of a cell.MS will receive identical power control from both sectors.
f1
f2
Hard Handoff
f1
f1
Soft Handoff
f1
Softer Handoff
112
Pilot Ec/I0
T_ADD
BS1 BS2
Pilot Ec/I0
T_DROP
BS1 BS2
cdma2000 CONCEPT: Soft Handoff
• Terms:Active Set: MS is in soft handoff.Candidate Set: MS identifies as strong.
• Parameters:T_ADDT_COMPT_DROPT_TDROP
Pilot Ec/I0
0.5xT_COMP
BS1 BS2
113
CDMA Soft Handoff Completion
• First Base Station Orders Soft Handoff with new Walsh Assignment
• MTSO Sends Land Link to Second Base Station• Mobile Receives Power from Two Base Stations• MTSO Chooses Better Quality Frame Every 20 Milliseconds
MTSO
Base Station 1
Land Link
Vocoder/ Selector
Base Station 2
114
Ending CDMA Soft Handoff
• First BS Pilot Power Goes Low at Mobile Station (drops below T_drop)
• Mobile Sends Pilot Strength Message• First Base Station Stops Transmitting and Frees up Channel• Traffic Channel Continues on Base Station Two
115
CDMA End of Call
• Mobile or Land Initiated• Mobile and Base Stop Transmission• Land Connection Broken
116
cdma2000 Standards Overview - TIA/EIA-98-D/E
• I.e.3GPP2 C.S0011-A/B:“Recommended Minimum Performance Standards for cdma2000 Spread Spectrum Mobile Stations.”
• Important test sections:2 Standard Radiated Emissions Measurement Procedure3 CDMA Receiver Minimum Standards4 CDMA Transmitter Minimum Standards
• Covers both SR1 and SR3No Minimum Standards specified for SR3.This presentation only covers SR1 testing.
117
CDMA Service Options
Service Options Are:11-- Voice Using 9600 bps ISVoice Using 9600 bps IS--9696--A A VocoderVocoder22-- Rate Set 1 Rate Set 1 LoopbackLoopback (9600 bps)(9600 bps)33-- Voice Using 9600 bps (EVRC)Voice Using 9600 bps (EVRC)44-- Asynchronous Data Service (circuit switched)Asynchronous Data Service (circuit switched)55-- Group 3 FaxGroup 3 Fax66-- Short Message Service (9600 bps)Short Message Service (9600 bps)77-- Internet Standard PPP Packet Data Internet Standard PPP Packet Data 88-- CDPD Over PPP Packet DataCDPD Over PPP Packet Data99-- Rate Set 2 Rate Set 2 LoopbackLoopback (14400 bps)(14400 bps)1414--Short Message Service (14400 bps)Short Message Service (14400 bps)32,76832,768-- Voice Using 14400 bps (CDG)Voice Using 14400 bps (CDG)
118
Section 3 - Receiver Test
Receiver Test3.1 Frequency Coverage Requirements3.4.1 Demod of Fwd Traffic Channel with AWGN3.4.2 Demod of Fwd Traffic Channel with Multipath Fading3.5.1 Receiver Sensitivity and Dynamic Range3.5.2 Single Tone Desensitization3.5.3 Intermodulation Spurious Response Attenuation3.5.4 Adjacent Channel Selectivity3.5.5 Receiver Blocking Characteristics3.7.1 Supervision Paging Channel
119
Section 4 - Transmitter Test
Transmitter Test4.1 Frequency Accuracy4.2 Handoff4.3 Modulation Requirements4.4 RF Output Power Requirements
4.4.1 4.4.1 Range of Open Loop Output PowerRange of Open Loop Output Power4.4.2 Time Response of Open Loop Power Control4.4.2 Time Response of Open Loop Power Control4.4.3 Access Probe Output Power4.4.3 Access Probe Output Power4.4.4 Range of Closed Loop Power Control4.4.4 Range of Closed Loop Power Control4.4.5 Maximum RF Output Power4.4.5 Maximum RF Output Power4.4.6 Minimum Controlled Output Power4.4.6 Minimum Controlled Output Power4.4.7 Standby Output Power and Gated Output Power4.4.7 Standby Output Power and Gated Output Power4.4.8 Power Up Function Output Power4.4.8 Power Up Function Output Power4.4.9 Code Channel to Reverse Pilot Channel Output Power Accurac4.4.9 Code Channel to Reverse Pilot Channel Output Power Accuracyy4.4.10 Reverse Pilot Channel Transmit Phase Discontinuity4.4.10 Reverse Pilot Channel Transmit Phase Discontinuity4.4.11 Reverse Traffic Channel Output Power During Changes in Da4.4.11 Reverse Traffic Channel Output Power During Changes in Data ta
RateRate
120
CDMA Conclusions
• New Access MethodCode Based
• Designed for Use in Interfering Environment• Uses Multipath to Improve Reception in Fading Conditions• cdma2000 is Backwards Compatible with TIA/EIA-95-B• Provides 2x Capacity Improvement Over TIA/EIA-95-B
Improved CodingImproved CodingImproved ModulationImproved ModulationCoherent Reverse Link Demodulation (Mobile Pilot)Coherent Reverse Link Demodulation (Mobile Pilot)Fast Forward Link Power ControlFast Forward Link Power Control
• Has Options for Green Field and Overlay Operation:Direct Spread for Green Field Spectrum ApplicationsDirect Spread for Green Field Spectrum Applications
• Supports High Speed Data for New Applications
