2. 2
Agenda
• CDMA introduction
• CDMA makes use of Diversity
• Power control
• CDMA Forward Link
• CDMA Reverse Link
• CDMA call processing
• CDMA Measurement
4. 4
User #3
Frequency Domain
User #2
User #1
Synch
Paging
Pilot
1.2288 MHz
freq
Code Domain
0 1 2 3 4 5 6 7 8 9 32 40 63
User
1
User
3
User
2
Walsh Code
Pilot Paging Synch
Code Domain Power (cdma2000/IS-95)
The CDMA Concept
5. 5
CDMA is Also Full Duplex
US Cellular Channel 384
Amplitude
Frequency
AMPS
CDMA
Frequency
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. 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
8. 8
The CDMA Concept
Baseband
Data
Encoding &
Interleaving
Walsh Code
Spreading
Walsh Code
Correlator
Baseband
Data
Decode & De-
Interleaving
0 0
fc
fc
fc
fc
fc
fc
10 Khz BW 1.23 Mhz BW 10 Khz BW
1.23 Mhz BW
1.23 Mhz BW
1.23 Mhz BW
Spurious Signals
-113 dBm/1.23 Mhz
CDMA
Transmitter
CDMA
Receiver
9.6 kbps 19.2 kbps 1228.8 kbps 9.6 kbps
19.2 kbps
1228.8 kbps
Background Noise External Interference Other Cell Interference Other User Noise
Interference Sources
9. 9
z 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. 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. 11
Direct Sequence Spread Spectrum
Source Information
Bits
I-Q Modulator
Carrier
Code Generator Bit
Stream
Transmit
DSSS Signal
Block diagram of a Direct Sequence Spread
Spectrum Transmitter
Bits to
I-Q
12. 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. 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. 14
Auto-Correlation
• Is a Comparison of a Signal
Against Itself
• Good Pseudo-Random
Patterns Have:
¾ Strong Correlation at Zero Time
Offset
¾ Weak Correlation at Other
Time Offsets
Pseudo-Random Sequence
Auto-Correlation Versus Time Offset
1
0
1
30
0 5 10 15 20 25
0 10 20
5 15 25 30
0
Chip Offset
15. 15
Analog
Analog
CDMA Paradigm Shift
¾ Multiple Users on One Frequency
9
9 Analog/TDMA Try to Prevent Multiple Users
Analog/TDMA Try to Prevent Multiple Users
Interface
Interface
¾ Channel is Defined by Code
9
9 Analog Systems Defined Channels by
Analog Systems Defined Channels by
Frequency
Frequency
¾ Traditional FDMA/TDMA are capacity-
limited
9
9 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;
9
9 To increase the number of users in the
To increase the number of users in the
system, frequency reuse is used
system, frequency reuse is used
¾ Capacity Limit is Soft
9
9 Allows Degrading Voice Quality to
Allows Degrading Voice Quality to
Temporarily Increase Capacity
Temporarily Increase Capacity
9
9 Reduce Surrounding Cell Capacity to
Reduce Surrounding Cell Capacity to
Increase a Cell
Increase a Cell’
’s Capacity
s Capacity
CDMA
16. 16
CDMA Capacity Gains
Processing
Processing
Gain
Gain
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. 17
CDMA makes use of Diversity
• Spatial Diversity
¾ Making Use of Differences in Position
• Frequency Diversity
¾ Making Use of Differences in Frequency
• Time Diversity
¾ Making Use of Differences in Time
18. 18
CDMA Spatial Diversity
• Diversity Reception:
¾ Multiple Antennas at Base Station
9
9Each Antenna is Affected by
Each Antenna is Affected by Multipath
Multipath Differently Due to Their
Differently Due to Their
Different Location
Different Location
9
9Allows Selection of the Signal Least Affected by
Allows Selection of the Signal Least Affected by Multipath
Multipath
Fading
Fading
• If Diversity Antennas are Good, Why Not Use Base Stations
as a Diversity Network?
¾ Soft Handoff
20. 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 BW
Amplitude
Frequency
21. 21
CDMA Time Diversity
• Rake Receiver to Find and Demodulate
Multipath Signals
• Data is Interleaved
¾Spreads Adjacent Data in time to Improve
Error Correction Efficiency
• Convolutional Encoding
¾Adds Error Correction and Detection
• Viterbi Decoding
¾Most Likely Path Decoder for
Convolutionaly Encoded Data
25. 25
Synchronization
• All Direct Sequence, Spread
Spectrum Systems Should be
Accurately Synchronized for
Efficient searching
• Finding the Desired Code
Becomes Difficult without
Synchronization
26. 26
Power Control
Near-end Far-end Problem
- 60dBm
- 30dBm
A
B
At the BS receiver,
SNR for A reception = 30 dB, certified
SNR for B reception = -30 dB, not certified
27. 27
z Acceptable SNR is at least 7 dB
z For B, the signal needs 37 dB gain to meet the condition
z 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. 28
z In this case, B is the Signal and A is the Noise
z Both A and B are transmitting at constant power
z Since A is near, it can be asked to transmit at low power
z Since B is far, it can increase the power
This is Power Control !
This is Power Control !
z Base Station will change power levels based on
the Path loss.
z Base Station will also command Mobile to
increase or decrease power levels.
Power Control
29. 29
• Maximum System Capacity is Achieved if:
9 All Mobiles are Power Controlled to the Minimum
Power for Acceptable Signal Quality
9 As 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 are
Always Both Active
Always Both Active
Reverse Link Power Control
30. 30
Open Loop Power Control
• Assumes Loss is Similar on Forward and Reverse
Paths
• Receive Power + Transmit Power = -73(-76dB for
PCS Band
¾ All Powers in dBm
• Example:
¾ For a Received Power of -85 dBm
Transmit Power = (
Transmit Power = (-
-73)
73) -
- (
(-
- 85)
85)
Transmit Power = +12
Transmit Power = +12 dBm
dBm
• Provides an Estimate of Reverse TX Power for Given
Propagation Conditions
31. 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. 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?
¾ Mobile Transmits in Bursts of 1.25 ms
• System Capacity Increases by 1/Voice Activity Factor
33. 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. 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. 35
CDMA Protocol Stacks
IS -95 Rev 0
Original System-never actually deployed
ARIB T53
Japan CDMA
System Cellular
Protocol
IS -95 Rev A
Backwards compatible with IS-95. First Deployed Protocol
TBS- 74
Cellular Protocol that adds 14400 Channel Support
J-STD-008
Not Backwards Compatible, PCS only Protocol
EIA/TIA-95 Rev B
Combines TSB-74 & J-STD-008 for a Universal Protocol
EIA/TIA/IS-2000 Rev 0
First release of IS-2000 standard(add QPCH)
EIA/TIA/IS-2000 Rev A
Add BCH,CCCH,CACH…new channel
EIA/TIA/IS-2000 Rev B
Add new functionality and support
EIA/TIA/IS-2000 Rev C(1x EV-DV)
Segment channel between Voice and Data
EIA/TIA/IS-856(1x EV-DO)
Optimized for packet data.
36. 36
The architecture for CDMA2000
IS634
PSDN
MSC
HLR/AUC
HLR/AUC
Laptops with
Cell Phones
Cell
Phones
Smartphones
and PDAs
BSC
AAA
AAA
Server
Server
PSTN
Internet
IWF
IP Router
Core
Elements
Core
Elements
From CDG
37. 37
cdma2000 Key Standards
• EIA/TIA/IS-2000 rev. 0 Interoperability Standard for
cdma2000 Spread Spectrum Systems
¾Defines channel coding, call processing procedures, protocol
and other mobile / base procedures and RF requirements to
ensure interoperability of equipment from multiple vendors
¾Defines how entire system works together in extreme detail
¾Revision 0 was first release of standard.
¾Revision A adds enhanced channels for paging, call set-up and
call control.
¾Revision B enhanced from the cdma2000 Release A
specifications
39. 39
Benefits of cdma2000
• Improved Performance and Capacity:
¾ About 2X Voice Capacity of TIA/EIA-95-B
¾ Handles a Wide Range of Data Rates:
9
9Voice and Low Speed Data while Driving
Voice and Low Speed Data while Driving
9
9Up to 384 kbps Packet or Circuit Data while Moving
Up to 384 kbps Packet or Circuit Data while Moving
9
9Up to 2 Mbps Data Rates for Fixed Installations
Up 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. 40
cdm
a
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. 41
Reuse of TIA/EIA-95-B
• cdma2000 is Fully Backwards Compatible with TIA/EIA-95-B
• Reused Aspects of TIA/EIA-95-B:
9
9 TIA/EIA
TIA/EIA-
-95
95-
-B Air Interface (RC1, RC2)
B Air Interface (RC1, RC2)
9
9 IS
IS-
-127 EVRC 8 kbps
127 EVRC 8 kbps Vocoder
Vocoder and IS
and IS-
-733 13 kbps
733 13 kbps Vocoder
Vocoder
9
9 All Existing Service Options
All Existing Service Options
9
9 IS
IS-
-637 SMS & IS
637 SMS & IS-
-683 Over the Air Activation
683 Over the Air Activation
9
9 IS
IS-
-98 and IS
98 and IS-
-97 Minimum Performance Standards
97 Minimum Performance Standards
9
9 Common Broadcast Channels (Pilot, Sync ,Paging)
Common Broadcast Channels (Pilot, Sync ,Paging)
• Allows cdma2000 to be Deployed Sooner
42. 42
Terms and Definitions
• Chip
9
9Is the period of a data bit at the final spreading rate
Is the period of a data bit at the final spreading rate
• SR - Spreading Rate
9
9Defines 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 Mcps
Mcps system is called a SR3 system.
system is called a SR3 system.
• RC - Radio Configuration
9
9Defines the physical channel configuration based upon a base
Defines the physical channel configuration based upon a base
channel data rate.
channel data rate.
9
9RCs
RCs 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.
9
9RCs
RCs are coupled to specific Spreading Rates
are coupled to specific Spreading Rates
43. 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
¾ Forward Link:
9
9Adds Fast Power Control
Adds Fast Power Control
9
9Quick Paging Channel to Improve Standby Time
Quick Paging Channel to Improve Standby Time
9
9Uses 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
¾ Reverse Link:
9
9Uses Pilot Aided BPSK to Allow Coherent Demodulation
Uses Pilot Aided BPSK to Allow Coherent Demodulation
9
9Uses 1/4 Rate
Uses 1/4 Rate Convolutional
Convolutional Encoder Instead of 1/2 or 1/3
Encoder Instead of 1/2 or 1/3
9
9Uses HPSK Spreading
Uses HPSK Spreading
• Doubles System Voice Capacity
44. 44
SR1 Forward Radio Configurations
• Radio Configuration 1 - Required
9
9Backwards compatible mode with TIA/EIA
Backwards compatible mode with TIA/EIA-
-95
95-
-B
B
9
9Based on 9,600 bps Traffic(RS1)
Based on 9,600 bps Traffic(RS1)
• Radio Configuration 2
9
9Backwards compatible mode with TIA/EIA
Backwards compatible mode with TIA/EIA-
-95
95-
-B
B
9
9Based on 14,400 bps Traffic(RS2)
Based on 14,400 bps Traffic(RS2)
• Radio Configurations 3, 4, and 5
9
9All use new cdma2000 coding for improved capacity
All use new cdma2000 coding for improved capacity
9
9RC3 is based on 9,600 bps and goes up to 153,600 bps
RC3 is based on 9,600 bps and goes up to 153,600 bps
9
9RC4 is based on 9,600 bps and goes up to 307,200 bps
RC4 is based on 9,600 bps and goes up to 307,200 bps
9
9RC5 is based on 14,400 bps and goes up to 230,400 bps
RC5 is based on 14,400 bps and goes up to 230,400 bps
45. 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
¾ 0 to 3 F-QPCH (Quick Paging Channel)
• IS-2000 Rev.A/B
¾ 0 or 8 F-BCH (Broadcast Channel)
¾ 0 to 4 F-CPCCH (Common Power Control Channel)
¾ 0 to 7 F-CACH (Common Assignment Channel)
¾ 0 to 7 F-CCCH (Common Control Channels)
• Many F-Traffic Channels, Each Consisting of:
9
9 0 or 1 F
0 or 1 F-
-DCCH (Dedicated Control Channels)
DCCH (Dedicated Control Channels)
9
9 1 F
1 F-
-FCH (Fundamental Channel)
FCH (Fundamental Channel)
9
9 0 to 7 F
0 to 7 F-
-SCCH (Supplemental Code Channels for RC1 & RC2)
SCCH (Supplemental Code Channels for RC1 & RC2)
9
9 0 to 2 F
0 to 2 F-
-SCH (Supplemental Channel for RC3, 4, 5)
SCH (Supplemental Channel for RC3, 4, 5)
46. 46
Base Station Variable Rate Vocoder
• Base Stations Do Not Pulse TX Channels
• How Does the Base Station Handle Variable
Rate Vocoding?
¾Repeats Data Bits When Transmitting at
Reduced Rates
¾Repeating Data Adds 3 dB Coding Gain
¾Lowers the TX Power 3dB for Each Lower
Rate
47. 47
Walsh Code
Generator
Forward Link Traffic Channel Physical Layer
(RC1,RC2)
1/2
Rate
3/4
Rate
P.C.
Mux
Vocoded
Speech
Data
20 msec
blocks
Convolutional
Encoder Interleaver
Long Code
Scrambling
Power
Control
Puncturing
800 bps Walsh
Coder
9.6
kbps
14.4
kbps
19.2
kbps
19.2
kbps
Long Code
19.2
kbps
19.2
kbps
19.2
kbps
19.2
kbps
1.2288 Mbps
1.2288 Mbps
1.2288
Mbps
1.2288
Mbps
Short Code Scrambler
800
bps
FIR
FIR
I
Q
I Short Code
Q Short Code
48. 48
Forward FCH Physical Layer
RC3 (9.6 kbps)
Optional
Can be Carried by F-DCCH
8.6 kbps
1228.8 kbps
Long Code
Decimator
Interleaver
38.4 ksps
1/4 Rate Conv.
Encoder
38.4 ksps
9.6 kbps
Long Code
Generator
38.4 kbps
Power
Control
Puncture
Walsh 64
Generator
1228.8 kcps
1228.8 kcps
1228.8 kbps
1228.8kbps
Q
I
S -P
800 bps
PC
User Long
Code Mask
Q
I
PC
Dec
1228.8 kcps
Q Short Code
I
Q
1228.8 kcps
Complex
Scrambling
Q
I
FIR
FIR
I Short Code
Orthogonal
Spreading
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
Puncture
Timing
Full Rate
Data Bits
Add CRC and
Tail Bits
800 bps
49. 49
CDMA Vocoders
• Vocoders Convert Voice to/from Analog Using Data
Compression
• There are Three CDMA Vocoders:
¾ IS-96A Variable Rate (8 kbps maximum)
¾ CDG Variable Rate (13 kbps maximum)
¾ EVRC Variable Rate (improved 8 kbps)
• Each has Different Voice Quality:
• IS-96A - moderate quality
• EVRC - near toll quality
• CDG - toll quality
50. 50
15
24 bits in a ms frame
39
79
171 266
124
54
20
1200 bps
Frame
8
Mixed Mode Bit Information Bits
1-bit
Reserved
8
8
8
8
12 12 8
10 8
6
8
8
8
Mixed Mode Bit
Mixed Mode Bit
Mixed Mode Bit
Information Bits
Information Bits
Information Bits
2400 bps
Frame
9600 bps
Frame
4800 bps
Frame
192 bits in a ms frame
96 bits in a ms frame
48 bits in a ms frame
1800 bps
Frame
3600 bps
Frame
7200 bps
Frame
14400 bps
Frame
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-bit
Reserved
1-bit
Reserved
1-bit
Reserved
Mixed
Mode Bit
Mixed
Mode Bit
Mixed
Mode Bit
Mixed
Mode Bit
Encoder
Tail Bits
CRC
CRC
Encoder
Tail Bits
Encoder
Tail Bits
Encoder
Tail Bits
Information Bits
Information Bits
Information Bits
Information Bits
Encoder
Tail Bits
Encoder
Tail Bits
Encoder
Tail Bits
Encoder
Tail Bits
CRC
CRC CRC
CRC
CDMA Frame Formats
51. 51
Forward Error Protection
• Uses Half-Rate Convolutional Encoder
• Outputs Two Bits of Encoded Data for Every Input Bit
Data Out
9600 bps
Data Out
9600 bps
D D
D
D
D D D D
+
+
Data In
9600
bps
z
z
z
z z z
z
52. 52
14.4 Traffic Channel Forward Link
Modifications
• Replaces 8 kbps Vocoder with a
13 kbps Vocoder(both Variable
Rate)
• Effects:
¾ Provides Toll Quality Speech
¾ Uses a 3/4 Rate Encoder
¾ Reduces Processing Gain 1.76 dB
¾ Results in Reduced Capacity or
Smaller Cell Sizes
3/4
rate
Vocoded
Speech
Data
Convolutional
Encoder
20 msec
blocks
14.4
kbps
19.2
kbps
53. 53
• 384 symbols are sequentially written in an input array
• Interleaved symbols are then read from the output array
19.2 ksps
9.6 ksps
4.8 ksps
2.4 ksps
Symbol
Repetition
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. 54
CDMA System Time
• How Does CDMA Achieve
Synchronization for Efficient
searching?
¾ Use GPS Satellite System
• Base Stations Use GPS Time
via Satellite Receivers as a
Common Time Reference
• GPS Clock Drives the Long
Code Generator
1
12
2
3
4
5
6
7
8
9
10
11
55. 55
Modulo-2 Addition
Long Code Output
Long Code Generator
1
User Assigned
Long Code Mask
42 bits
2
4 3
42 41 5
Long Code Generation
56. 56
Long Code Generation
Modulo-2 Addition
Long Code Output
3
4 1
2
User Assigned
Long Code Mask
42 bits
41
42 5
Long Code Generator
(Driven by System Time)
1100011000 Permuted ESN
41 32 31 0
Long Code Mask
57. 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. 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 Code
Scrambled
Voice Data
Long Code
Decimated
Data
Closed Loop
Power
Control Bits
P. C.
Mux
Long Code
Decimator
800 bps
800 bps
19.2 kbps
19.2 kbps
59. 59
Power Control Bit Puncturing
z 19.2 ksps: 384 symbols / 20ms frame
z Each 20ms frame is divided into 16 power control
group (1.25 ms each)
z 24 modulation symbols in each power control group
Long Code Decimated
Data Decimator
19.2 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. 60
Payload
Data Bits
1228.8 kbps
Long Code
Decimator
Interleaver
1/2 Rate
Convolutional
Encoder
307.2 ksps
Channel
Coder
Add CRC and
Tail Bits
153.6 kbps
Long Code
Generator
User Long
Code Mask
Decimate by
Walsh Length/2
307.2 ksps
307.2 ksps
307.2 ksps
Gain
Walsh 8
Generator
1228.8 kcps
1228.8 kcps
1228.8 kbps
1228.8kbps
Q
I
S -P
Q
I
1228.8 kcps
Q Short Code
I
Q
1228.8 kcps
Complex
Scrambling
FIR
FIR
I Short Code
Orthogonal
Spreading
1228.8 kcps
1228.8 kcps
+
+
+
-
153.6 ksps
153.6 ksps
152.4 kbps
SR1, RC4 (152.4 kbps) F-SCH
61. 61
Walsh Codes
W=
0 0
0 1
W= 0
0 0 0 0
0 1 0 1
0 0 1 1
0 1 1 0
W=
1
2
4
=
n
n
n
n
n
W
W
W
W
W
2
62. 62
2 Match - 2 don’t = 0
Checking for Orthogonality
W =
4
0 0 0 0
0 1 0 1
0 0 1 1
0 1 1 0
0 0 0 0
0 0 1 1
Y Y N N
Cross
Correlation
=
N agreements
- N disagreements
Ntotal_number_of_digits
65. 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 Coded
Data at
1.2288 Mbps
1.2288 Mbps
1.2288 Mbps I Channel Short
Sequence Code
Generator
Q Channel Short
Sequence Code
Generator
To I/Q
Modulator
66. 66
Multi-Layer Code Assignment
Walsh Code layer (spreading code)
Full code
set 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
Convolutional
Encoder
Long code
Walsh Code
Short Code
CDMA as an Onion
CDMA as an Onion
67. 67
Short Code (PN) Generation
z PN sequence codes are generated using 15-bit shift
registers
z PN sequence pattern repeats every 26.666 ms
z 75 PN sequences repetition occur every 2 seconds
z On every even second clock, MS will get PN sequence
initial state
Jan 6, 1980 00:00:00
1, 0, 0, 0.............. 0
R1,R2,R3,R4..........R15
( initial state of 15 registers )
PN Code Combinations: 215 = 32768
Clock Rate = 1.2288 Mcps
Return of Initial State = 26.666 ms
32768
3
2
7
6
8
1
2
74
75
32768
2 sec
26.666ms
68. 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. 69
Short Code Correlation
• Short Codes are Designed to
Have:
¾ Strong Auto-Correlation at Zero
Time Offset
¾ Weak Auto-Correlation at Other
Offsets
¾ Good Auto-Correlation in Very
Poor Signal-to-Noise Ratio
Environments
• Allows Fast Acquisition in Real
World Environment
Auto-Correlation Versus
Time Offset With 17 dB Noise Added
0 10 20
5 15 25 30
Chip Offset
70. 70
Convert to I/Q
& PN
Spreading
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
& PN
Spreading
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
& PN
Spreading
FIR LP Filter &
D/A Conversion
I Data
Q Data
1228.8 kbps
Walsh Codes 1 to 7
Paging Channels
1 up to 7 Channels
19.2 kbps
Convert to I/Q
& PN
Spreading
FIR LP Filter &
D/A Conversion
I Data
Q Data
1228.8 kbps
Walsh Codes 8-31,33-63
Traffic Channels
1 up to 55 Channels
19.2 kbps
I
Q
Forward Link Channel Format
Σ
Σ
71. 71
Walsh Coding Example
W2 =
0 0 - User A
0 1 - User B
-1
-2
+1
+2
-1
+1
Channel A
Walsh Encoded
Voice Data
+1
-1
Channel A
Voice Data
For a 1 Input
Use Code 11
+1
-1
For a 0 Input
Use Code 00
User A User B
For a 0 Input
Use Code 01
For a 1 Input
Use Code 10
Channel B
Voice Data
Channel B
Walsh Encoded
Voice Data
Sum of A & B
Walsh Encoded
Data Streams
0 0
1 1
0 0 1 1 0 0 0 0
+1
-1
+1
-1
0 1
1 0
-1
+1
1 0 0 1 0 1 1 0
+
0
+1
1 0 0 1
+1
0
1 0 0 1
72. 72
Walsh Decoding Example
Correlation Coefficient
f i (t) r f j (t) dt
z i j =
1
T
+1
0
1 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
0
1 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
-1
1 0
1
+1
-1
+2
-2
= = = =
+
∫
0
T
∫
73. 73
What if Walsh Codes are Not Time Aligned ?
Channel B
Walsh
Encoded
Voice Data -1
+1
1 0 0 1 0 1 1 0
-1
+1
Channel A
Walsh
Encoded
Voice Data
0 0 1 1 0 0 0 0
-1
-2
+1
Sum of A & B
Walsh Encoded
Data Streams
Original Data Was
0 (-1), We Have
Interference 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. 74
Pilot Channel Physical Layer
Walsh
Modulator
1.2288 Mbps
1.2288 Mbps
1.228
8
Mbps
1.228
8
Mbps
Short Code Scrambler
FIR
FIR
I
Q
Walsh Code
Generator Q Short Code
I Short Code
All 0
Inputs
19.2
kbps
Walsh
Code 0
• Uses Walsh Code 0:
¾ 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
76. 76
Paging Channel Physical Layer
Paging Channel
Long Code
1/2
Rate
Convolutional
Encoder
Interleaver
4.8
kbps
9.6
kbps
19.2
kbps
Paging
Channel
Message
Data
2x
Symbol
Repetition
19.2
kbps
Walsh
1 to 7
Coder
1.2288 Mbps
1.2288 Mbps
1.2288
Mbps
1.2288
Mbps
Short Code Scrambler
I
Q
Walsh Code
Generator QShort Code
Long Code
Scrambling
19.2
kbps
19.2
kbps
FIR
I Short Code
FIR
77. 77
SR1 Reverse Radio Configurations
• Radio Configuration 1 - Required
9
9 Backwards compatible mode with TIA/EIA
Backwards compatible mode with TIA/EIA-
-95
95-
-B
B
9
9 Based on 9,600 bps Traffic
Based on 9,600 bps Traffic
• Radio Configuration 2
9
9 Backwards compatible mode with TIA/EIA
Backwards compatible mode with TIA/EIA-
-95
95-
-B
B
9
9 Based on 14,400 bps Traffic
Based on 14,400 bps Traffic
• Radio Configurations 3 and 4
9
9 All use new IS
All use new IS-
-2000 coding for improved capacity
2000 coding for improved capacity
9
9 RC3 is based on 9,600 bps and goes up to 307,200 bps
RC3 is based on 9,600 bps and goes up to 307,200 bps
9
9 RC4 is based on 14,400 bps and goes up to 230,400 bps
RC4 is based on 14,400 bps and goes up to 230,400 bps
78. 78
SR1 Reverse Channels
• Each Mobile Transmits Several
Channels:
¾
¾ 1 R
1 R-
-Pilot
Pilot (Reverse Pilot)
9
9 Includes Power Control Sub
Includes Power Control Sub-
-Channel
Channel
¾
¾ 1 R
1 R-
-ACH or R
ACH or R-
-EACH
EACH (Access or Enhanced Access Channel)
9
9 Used to Initiate Calls
Used to Initiate Calls
¾
¾ 0 or 1 R
0 or 1 R-
-CCCH
CCCH (Common Control Channel)
9
9 Used to Initiate Calls in the Reservation Access Mode
Used to Initiate Calls in the Reservation Access Mode
¾
¾ 0 or 1 R
0 or 1 R-
-DCCH
DCCH (Dedicated Control Channel)
9
9 Provides Signaling while a Traffic Channel is Active
Provides Signaling while a Traffic Channel is Active
¾
¾ 0 or 1 R
0 or 1 R-
-FCH
FCH (Reverse Fundamental Channel)
9
9 Primary Channel, usually Voice
Primary Channel, usually Voice
¾
¾ 0 to 2 R
0 to 2 R-
-SCHs
SCHs (Reverse Supplemental Channels)
9
9 Carries High Speed Data
Carries High Speed Data
79. 79
R-FCH Coding for SR1(RC1,RC2)
1/2
Rate
Vocoded
Speech
Data
20 msec
blocks
Convolutional
Encoder
Interleaver
9.6
kbps
14.4
kbps
28.8
kbps
28.8
kbps
28.8
kbps
1.2288 Mbps
1.2288
Mbps
Short Code Scrambler
I
Q
1/3
Rate
Long Code
64-ary
Modulator
1 of 64
Walsh Codes
Walsh
Code 2
Walsh
Code 63
Walsh
Code 62
Walsh
Code 61
Walsh
Code 1
Walsh
Code 0
Long Code
Modulator
307.2
kbps
1.2288
Mbps
1.2288 Mbps
Q Short Code
FIR
I Short Code
FIR
t/ 2
1/2 Chip Delay
80. 80
Reverse Error Protection
• Uses Third-Rate Convolutional Encoder
• Outputs Three Bits for Every Input Bit
Data Out
9600 bps
D D
D
D
D D D D
+
+
Data
Out
9600
bps
+
Data In
9600
kbps
Data Out
9600 bps
z z z z z z z z
z
z
z
81. 81
14.4 Traffic Channel Reverse Link
Modifications
• Replaces 8 kbps Vocoder with
a 13 kbps Vocoder (both
Variable Rate)
• Effects:
¾ Provides Toll Quality Speech
¾ Uses a 1/2 Rate Encoder
¾ Reduces Processing Gain 1.76
dB
¾ Results in Reduced Capacity
or Smaller Cell Sizes
1/2
Rate
Vocoded
Speech
Data
20 msec
blocks
Convolutional
Encoder
14.4
kbps
28.8
kbps
82. 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
¾ (28.8 kbps * 64 bits) / 6 bits =
307.2 kbps)
• Is Not the Channelization for
the Reverse Link
307.2
kbps
28.8
kbps
>
Walsh
Code 2
Walsh
Code 1
Walsh
Code 0
Walsh
Code 63
Walsh
Code 62
Walsh
Code 61
83. 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. 84
Reverse Channel Long Code Spreading
• Long Code Spreading
Provides Unique Mobile
Channelization
• Mobiles are Uncorrelated but
not Orthogonal with Each Other
Long Code
Generator
Walsh
Modulated
Voice Data
XOR
307.2 kbps 1.2288 kbps
1.2288 kbps
86. 86
Data Burst Randomizer
Algorithm
At 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. 87
Gated-On and Gated-Off Power
7 us 7 us
20 dB or to
the noise
floor (-60dBm)
3 dB
1.247 ms
Mean output of the
ensemble average
Ensemble average: Average of power control groups,
all with the same output power
88. 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
FIR
t/ 2
1/2 Chip Delay
1.2288
Mbps
89. 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
n
00 01
10 11
I
Q
n
n n
n
00 01
10 11
91. 91
MUX
Pilot Data
Power
Control Bits
To I Channel
Summer
One Power Control Group
Pilot Pilot
Pilot 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. 92
R-FCH
Data Bits
8.6 kbps
Walsh Code
Generator
1 Frame
1/4 Rate
Convolutional
Encoder
38.4 ksps
Channel
Coder
Add CRC and
Tail 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 Frame
Orthogonal
Spreading
Spread
Factor = 16
2 Reps
Symbol
Repeat
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. 93
1,1,1,1,1,1,1,1,-1,-1,-1,-1,-1,-1,-1,-1
I Channel
Short Code
Generator
User Long
Code Mask
Complex
Scrambling
Q
I
+
+
+
-
R-DCCH
R-Pilot +
Power
Control
R-SCH 1
or
R-EACH
or
R-CCCH
R-FCH
Walsh 16
Generator
1,1, 1, 1 -1,-1, -1, -1, 1, 1, 1, 1, -1, -1, -1, -1
Walsh 2/4/8
Generator
1,-1 or 1 -1 1,-1, or 1,1,-1,-1,1,1,-1,-1
Walsh 16
Generator
1228.8 kcps
R-SCH 2
Walsh 4/8
Generator
1, 1, -1, -1 or 1, 1, -1, -1, -1, -1, 1, 1
Walsh 2
Generator
1,-1
Gain
Scale
Gain
Scale
Gain
Scale
Gain
Scale
Deci
by 2
1228.8 kcps
1228.8 kcps
1228.8 kcps
1228.8 kcps
1228.8 kcps
1228.8 kcps
1228.8 kcps
1228.8 kcps
Q Channel
Short Code
Generator
1228.8 kcps
1-Chip
Delay
Long Code
Generator
1,1,1,1,-1,-1,-1,-1 for
R-EACH or R-CCCH
SR1 Reverse Channel Spreading(RC3,RC4)
94. 94
Channelization Summary
Function
9.6 kbps
Convolutional Encoder
14.4 kbps
Convolutional Encoder
Walsh Coding
Long Code
Spreading
Short Code
Spreading
Forward Link
(Base to Mobile)
1/2 Rate
(9600 in 19200 out)
3/4 Rate
(14400 in 19200 out)
Channelization
Voice Privacy
Base Station
Identification
Reverse Link
(Mobile to Base)
1/3 Rate
(9600 in 28800 out)
1/2 Rate
(14400 in 28800 out)
64-ary
Modulation
Channelization
Aid Base Station
Searching
96. 96
Station Class Mark (SCM)
Extended SCM
Indicator
7 Band Class 0 0XXXXXXX
Band Class 1 1XXXXXXX
Dual Mode 6 CDMA Only X0 XXXXXX
Dual Mode X1XXXXXX
Slotted Class 5 Non-Slotted XX0XXXXX
Slotted XX1XXXXX
IS- 54 Power Class 4 Always 0 XXX0XXXX
25 MHz Bandwidth 3 Always 1 XXXX1XXX
Transmission 2 Continous XXXXX0XX
Discontinous XXXXX1XX
Power Class for Band
Class "0" Analog
Operation
( For CDMA only "00")
1- 0 Class I XXXXXX00
Class II XXXXXX01
Class III XXXXXX10
Reserved XXXXXX11
Function Bit(s) Setting
97. 97
Ten Minutes in the Life of a CDMA Mobile
Phone
• Turn-on
¾ System Access
• Travel
¾ Idle State Hand-Off
• Initiate Call
• System Access
• Continue Travel
¾ Initiate Soft Handoff
¾ Terminate Soft Handoff
• End Call
98. 98
CDMA Turn On Process
• Find All Receivable Pilot Signals
¾ Choose 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. 99
Sync Channel Message
• Contains the Following Data:
¾ Base Station Protocol Revision
¾ Min Protocol Revision
Supported
¾ SID, NID of Cellular System
¾ Pilot PN Offset of Base Station
¾ Long Code State
¾ System Time
¾ Leap Seconds From Start of
System Time
¾ Local Time Offset from System
Time
¾ Daylight Savings Time Flag
¾ Paging Channel Data Rate
¾ Channel Number
SYNC
100. 100
Read the Paging Channel
• Demodulate the Paging
Channel:
¾ 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. 101
CDMA Idle State Handoff
• No Call In Progress
• Mobile Listens to New Cell
• Move Registration Location if
Entering a New Zone
102. 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. 103
Access Probe
Access Channel Message
40 - 880 bits
Padding
as reqd
Frame Body
88 bits
T
8
Frame Body
88 bits
T
8
……
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 ]
Preamble
96 bits “0”s
Preamble
96 bits “0”s
PAM_SZ = No. of preamble frames
MAX_CAP_SZ = No. of message capsule frames
104. 104
Access Probe Sequence
Access Probe Sequence
Access
Probe 1
Access
Probe 2
Access
Probe 3
Access
Probe n
TA TA TA
RT RT RT
Preamble + Access Message Capsule
Max = 26 frames
RN RN RN RN
IP
P1
P2
P3
IP = Open Loop Power + NOM_PWR + INIT_PWR
where Open Loop Power = -( Received Power ) - 73
105. 105
Access Attempt
RS : Backoff delay, which is random value between 0 to BKOFF slots
Process for Response Messages
Process for Response Messages
message ready for
transmission
Access
Probe
Sequence
Access
Probe
Sequence
Access
Probe
Sequence
Access
Probe
Sequence
Access Attempt
MAX_RSP_SEQ
RS RS RS
106. 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 slot
The 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 Messages
Process for Request Messages
message ready for transmission
Access
Probe
Sequence
Access
Probe
Sequence
Access
Probe
Sequence
Access
Probe
Sequence
Access Attempt
MAX_REQ_SEQ
RS PD RS PD
RS PD
PD
107. 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 information
Page Response message
Authentication 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. 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 Numbers
bBase Station ID
bPilot PN Offset
109. 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. 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. 111
Hard, Soft, and Softer Handoffs
• Hard Handoff
¾ “Break before make.”
• Soft Handoff
¾ “Make before break.”
¾ MS communicates with more
than one BS at a time.
¾ Improves reception on cell
boundaries.
¾ MS will receive different power
control from the two BSs.
• Softer Handoff
¾ MS communicates with more
than one sector of a cell.
¾ MS will receive identical power
control from both sectors.
f1
f2
Hard Handoff
f1
f1
Soft Handoff
f1
Softer Handoff
112. 112
Pilot Ec/I0
T_ADD
BS1 BS2
Pilot Ec/I0
T_DROP
BS1 BS2
cdma2000 CONCEPT: Soft Handoff
• Terms:
¾ Active Set: MS is in soft
handoff.
¾ Candidate Set: MS identifies as
strong.
• Parameters:
¾ T_ADD
¾ T_COMP
¾ T_DROP
¾ T_TDROP
Pilot Ec/I0
0.5xT_COMP
BS1 BS2
113. 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
BaseStation1
LandLink
Vocoder/ Selector
BaseStation2
114. 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. 115
CDMA End of Call
• Mobile or Land Initiated
• Mobile and Base Stop Transmission
• Land Connection Broken
116. 116
cdma2000 Standards Overview - TIA/EIA-98-
D/E
• I.e.3GPP2 C.S0011-A/B:
¾ “Recommended Minimum Performance Standards for
cdma2000 Spread Spectrum Mobile Stations.”
• Important test sections:
¾ 2 Standard Radiated Emissions Measurement Procedure
¾ 3 CDMA Receiver Minimum Standards
¾ 4 CDMA Transmitter Minimum Standards
• Covers both SR1 and SR3
¾ No Minimum Standards specified for SR3.
¾ This presentation only covers SR1 testing.
117. 117
CDMA Service Options
¾ Service Options Are:
9
91
1-
- Voice Using 9600 bps IS
Voice Using 9600 bps IS-
-96
96-
-A
A Vocoder
Vocoder
9
92
2-
- Rate Set 1
Rate Set 1 Loopback
Loopback (9600 bps)
(9600 bps)
9
93
3-
- Voice Using 9600 bps (EVRC)
Voice Using 9600 bps (EVRC)
9
94
4-
- Asynchronous Data Service (circuit switched)
Asynchronous Data Service (circuit switched)
9
95
5-
- Group 3 Fax
Group 3 Fax
9
96
6-
- Short Message Service (9600 bps)
Short Message Service (9600 bps)
9
97
7-
- Internet Standard PPP Packet Data
Internet Standard PPP Packet Data
9
98
8-
- CDPD Over PPP Packet Data
CDPD Over PPP Packet Data
9
99
9-
- Rate Set 2
Rate Set 2 Loopback
Loopback (14400 bps)
(14400 bps)
9
914
14-
-Short Message Service (14400 bps)
Short Message Service (14400 bps)
9
932,768
32,768-
- Voice Using 14400 bps (CDG)
Voice Using 14400 bps (CDG)
118. 118
Section 3 - Receiver Test
Receiver Test
3.1 Frequency Coverage Requirements
3.4.1 Demod of Fwd Traffic Channel with AWGN
3.4.2 Demod of Fwd Traffic Channel with Multipath Fading
3.5.1 Receiver Sensitivity and Dynamic Range
3.5.2 Single Tone Desensitization
3.5.3 Intermodulation Spurious Response Attenuation
3.5.4 Adjacent Channel Selectivity
3.5.5 Receiver Blocking Characteristics
3.7.1 Supervision Paging Channel
119. 119
Section 4 - Transmitter Test
Transmitter Test
4.1 Frequency Accuracy
4.2 Handoff
4.3 Modulation Requirements
4.4 RF Output Power Requirements
4.4.1
4.4.1 Range of Open Loop Output Power
Range of Open Loop Output Power
4.4.2 Time Response of Open Loop Power Control
4.4.2 Time Response of Open Loop Power Control
4.4.3 Access Probe Output Power
4.4.3 Access Probe Output Power
4.4.4 Range of Closed Loop Power Control
4.4.4 Range of Closed Loop Power Control
4.4.5 Maximum RF Output Power
4.4.5 Maximum RF Output Power
4.4.6 Minimum Controlled Output Power
4.4.6 Minimum Controlled Output Power
4.4.7 Standby Output Power and Gated Output Power
4.4.7 Standby Output Power and Gated Output Power
4.4.8 Power Up Function Output Power
4.4.8 Power Up Function Output Power
4.4.9 Code Channel to Reverse Pilot Channel Output Power Accurac
4.4.9 Code Channel to Reverse Pilot Channel Output Power Accuracy
y
4.4.10 Reverse Pilot Channel Transmit Phase Discontinuity
4.4.10 Reverse Pilot Channel Transmit Phase Discontinuity
4.4.11 Reverse Traffic Channel Output Power During Changes in Da
4.4.11 Reverse Traffic Channel Output Power During Changes in Data
ta
Rate
Rate
120. 120
CDMA Conclusions
• New Access Method
¾Code 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
9
9 Improved Coding
Improved Coding
9
9 Improved Modulation
Improved Modulation
9
9 Coherent Reverse Link Demodulation (Mobile Pilot)
Coherent Reverse Link Demodulation (Mobile Pilot)
9
9 Fast Forward Link Power Control
Fast Forward Link Power Control
• Has Options for Green Field and Overlay Operation:
9
9 Direct Spread for Green Field Spectrum Applications
Direct Spread for Green Field Spectrum Applications
• Supports High Speed Data for New Applications
