CDMA Theory Module
Unit 1－－ CDMA Overview
Unit 2－－ CDMA Basic Principle
Unit 3－－ CDMA Channel Structure and
Modulation
Unit 4－－ CDMA Key Technology
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
CDMA Theory Unit 1
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Main Content





ZTE University
The history of mobile communication
CDMA evolution path
The advantage of CDMA
CDMA spectrum usage
Role of ZTE in CDMA
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Evolution of
Mobile Communications System
1G
Analog
cellular
Voice
2G
3G
Digital cellular
Digital cellular
Voice /data
Voice / high speed data
AMPS
CDMA
1XRtt
CDMA2000
TACS
GSM
GPRS
W_CDMA
1992
1999
20 01 2003
80’
AMPS: Advanced Mobile Phone System
TACS: Total Access Communication System
GPRS: General Packet Radio Services
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Mobile Communication Standards
2.5G
2G
cdmaOne
IS-95-A
• Voice
• 14.4 kbps CSD
CDMA2000
CDMA2000
1X 1X
Rel. 0
IS-95-B
Korea
Japan
• Voice
• 64 kbps Packet
• RF Backward
Compatible
ZTE University
3G
CDMA2000
CDMA2000
1xEVDO
1xEV-Rel. 0
CDMA2000
CDMA2000
1xEV- DORev.A
1xEVDO
Rel
•
• 2.4 Mbps PD
• High Capacity Voice
•
•
• RF Backward
Comp.
• Backward Comp.
• 153 kbps PD
FL 3.09Mbps PD
CDMA2000
CDMA2000
• RF Backward
CDMA2000
RL 1.8 Mbps PD
Comp.
1XRel.A
Rel A
• 307.2 kbps Packet
• Backward Comp.
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
1xEVDV Rel D
• FL 3.09 Mbps PD
• RL 1.8 Mbps PD
• Backward Comp.
univ.zte.com.cn
CDMA Status in The World
• At present, CDMA commercial networks are established in about 50
countries or area, almost 20% of all users in the world.
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Advantages of CDMA(1)
High privacy,hard to wiretapping
Each user is below
the noise deeply
Spread signal
Information
signal
Demodulated
signal
TX
Spread code
ZTE University
RX
Spread code
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Advantages of CDMA(2)
Good voice quality, uses 8k QCELP, 13K QCELP,8k EVRC, voice
coding - the best coding method in the world.
Voice quality
(MOS)
ZTE University
64k
PCM
13k
GSM
8k QCELP
CDMA
13k
QCELP
CDMA
8kEVRC
CDMA
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Advantages of CDMA (3)
Frequency reuse
factor is 1;
network design and
expanding become
much easier
AMPS, D-AMPS, N-AMPS
1
3
1 Users
30
30
10 kHz
2
3
7
1
6
4
5
Typical Frequency Reuse N=7
GSM
8
Users
1
4
2
3
200 kHz
Typical Frequency Reuse N=4
CDMA
1
20 Users
1250 kHz
1
1
1
1
1
1
1
1
1
1
1
1
1
Typical Frequency Reuse N=1
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Advantages of CDMA
Use soft handoff, decrease drop-call rate
CDMA System
”make before break”---soft handoff
ZTE University
Other systems:
“make after break” --------hard
handoff
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Advantages of CDMA(5)
Perfect Power Control and voice activation make the MS
Power low, healthy for body—green mobile phone.
Mean Power
Max
Power
ZTE University
GSM:
125mW
CDMA:
2mW
2W
200mW
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Advantages of CDMA(6)
large coverage
almost 2 times than GSM, save money for
operator
Example:cover 1000 km2： GSM need
200 BTS ，CDMA only need 50 BTS
Attention: exact result need
“Link Budget ”
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Advantages of CDMA(7)
High spectrum capacity，8--10 times than AMPS,4—6 times than
GSM
FDMA
FDMA---Different user use different
frequency
Power
TACS、AMPS
TDMA
TDMA---Different user use different time
slot of one frequency
Power
GSM、DAMPS
CDMA---Different user use same
frequency at the same time,but with
different spreading code
ZTE University
CDMA
Power
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Advantages of CDMA(8)
High speed packet switching structure, smooth migration to 3G !
the operator’s benefit is protected at the most !
95A  95B
Technical
Scheme：


Software update
Replace MS to
get new service
95B  1X



Economic
Scheme：
Almost free
ZTE University
Add 1X channel
board
Software update
Replace MS to get
new service
inexpensive
1X  1XEV


Add 1XEV
channel board
Software update
Replace MS to
get new service
inexpensive

The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
CDMA 800 MHz Cellular Spectrum Usage
Channel
Numbers
10
10
1.5
2.5
824
MHz
Reverse link (i.e., mobile transmits)
Possible CDMA
Center Freq. Assignments
849
MHz
799
1
other
uses
717
716
B’
667
666
A’
334
333
B
1
1023
A
991
799
717
716
667
666
334
333
1
1023
991
A”
A”
A
B
A’
B’
1
10
10
1.5
2.5
869
MHz
Forward link (i.e., cell site transmits)
894
MHz
~300 kHz. “guard bands” possibly required if adjacentfrequency signals are non-CDMA (AMPS, TDMA, ESMR, etc.)
• All CDMA RF carriers are 1.25 MHz. Wide
• Between CDMA carriers, no guard band
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
CDMA Frequency Channel
Assignment at 800 MHz Cellular
799
A Band
716
715
667
666
334
333
1
1023
991
A”
A’
B Band
B’
Channel
Numbers
1019
37
78
119
160
201
242
283
384
425
466
507
548
589
630
691
8
7
6
5
4
3
2
1
1
2
3
4
5
6
7
9
*
CDMA A-Band Carriers
CDMA B-Band Carriers
*
736
777
9
8
**
*
Requires frequency coordination with
non-cellular interferers
** Requires frequency coordination with
A-band carrier
A Band Primary Channel
A Band Secondary Channel
Channel number?
ZTE University
Center
frequency
283
691
B Band Primary Channel
B Band Secondary Channel
384
777
Up link: 825.00MHz+0.03MHz*N
Down link: 870.00MHz+0.03MHz*N
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
ZTE’s Activities in CDMA







In 1995, CDMA mobile telecommunication project was started
In November, 1999, ZTE signed the “Agreement on CDMA R&D” with
Qualcomm
In August, 2000, the first field trial was set up.
In September, 2000， ZTE presented the first CDMA handset with UIM
(User Identification Module) in the world.
In January, 2001, the first cdma2000-1x call was passed through in lab
In March, 2001, ZTE cdma2000-1x realized the integrated transmission of
voice, data & image.The data rate reach up to 153.6Kbps.
In 2003, ZTE first EV-DO all-IP trial network was set up.
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
ZTE－A Famous CDMA Brand
PSTN/PLMN
MSC/VLR
HLR/AUC
Abis
E1
BTS（IS-95）
Um
IS95
SC
BSC（IS-95）
Abis
BTS（IS-95）
WIN
IP
Um
HA
Abis
BSC/ PCF (1X)
IS2000
2G/3G
Terminals
E1
STM-1
OMC
E1
BTS（1X）
Ethernet
E1
STM-1
BTS（1X）
ZTE University
Router
BSC/ PCF (1X)
Router
IP
Ethernet
Abis
Internet
PDSN/FA
AAA
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
Server
univ.zte.com.cn
»ÝÑθßËÙ¹«Â·
ZTE Supply All Service
Network Simulation
·ï»
Ë´ó
µÀ
Èý
Ê
®Ò
Wireless Network
Optimization
ȼ
ÅÂ
·
ÐÂ
·
ºÉ
Áú¸ñ·
·
«Â
Éî¹
¶«
ì·
퓦
³¤ ½ðÔ
½
-Æ F´Â·
ÒÂ
·
F
Ûê±³
·
H
·
ºáƺ¹«
´ïÂ
¹ã
±Â ´ó¿µÄÏ·
·
Ô
¹«
·
·
ºá
¿Ó
°Â
H
°²Á
K
¸£¿
Ó·
·
ªÂ
°²B»
µ¤É³Â·
F
·
Òµ
ʵ
·
¼Â
»·³Ç¶«Â·
µ±
A
B
·
G
À
¨µ
ÄÏÍ B
F
´ó¿µÂ·
´ó
¿
·
A
·
ºÍÂ
Áù
·
ÍÂ
»·º
Network Planning
H
·
B
B
B
Á¬ÐÄ
·
·É
Áú
ţʼÆÒ·
µÚ
H
H G
B F
´óÍò
HL
·
±Â
DZ
»·³
·
Ê¢
ºìÃÞ¶
þ·
·
F
ï
Â
Áë
«
ºá¶
µÀ
¶þͨ
ÐÂB
Ô°
·
·
ÐBË
ÍúÂ
F
B
²¼É³
·
Ñΰ
Ó¸ß
ËÙ
¹«
·
Ïɺþ·
°®»ªÂ·
Network Optimization Simulation
Maintenance Optimization
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
ZTE Supply All Products
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
CDMA Theory Unit 2
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Main Content
 Definitions of CDMA and How to realize
Spread spectrum modulation
Spreading codes used in CDMA
Vocoding in CDMA
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Multiple Access
Multiple Access: Simultaneous private use of a transmission
medium by multiple, independent users.
Since the beginning of telephony and radio,
system operators have tried to squeeze the
maximum amount of traffic over each circuit.
•
•
Types of Media -- Examples:
– Twisted pair - copper
– Coaxial cable
– Fiber optic cable
– Air interface (radio signals)
Advantages of Multiple Access
– Increased capacity: serve more users
– Reduced capital requirements since
fewer media can carry the traffic
– Decreased per-user expense
– Easier to manage and administer
ZTE University
Transmission
Medium
Each pair of users
enjoys a dedicated,
private circuit through
the transmission
medium, unaware that
the other users exist.
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Channels
Channel: An individually-assigned, dedicated
pathway through a transmission
medium for one user’s information.
The transmission medium is a resource that can be subdivided
into individual channels according to the technology used.
• FDMA Frequency Division Multiple Access
– Each user on a different frequency
– A channel is a frequency
• TDMA Time Division Multiple Access
– Each user on a different window period in
time (“time slot”)
– A channel is a specific time slot on a
specific frequency
• CDMA Code Division Multiple Access
– A channel is a unique code pattern
– Each user uses the same frequency all the
time, but mixed with different
distinguishing code patterns
ZTE University
FDMA
Power
TDMA
Power
CDMA
Power
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Defining Our Terms
•
CDMA Channel or CDMA Carrier or CDMA Frequency
– Duplex channel made of two 1.25 MHz-wide bands of electromagnetic spectrum, one for
Base Station to Mobile Station communication (called the FORWARD LINK or the
DOWNLINK) and another for Mobile Station to Base Station communication (called the
REVERSE LINK or the UPLINK)
– In 800 Cellular these two simplex 1.25 MHz bands are 45 MHz apart
– In 1900 MHz PCS they are 80 MHz apart
CDMA CHANNEL
•
CDMA Forward Channel
– 1.25 MHz Forward Link
•
•
CDMA Reverse Channel
– 1.25 MHz Reverse Link
CDMA
Reverse
Channel
CDMA
Forward
Channel
1.25 MHz
1.25 MHz
45 or 80 MHz
CDMA Code Channel
– Each individual stream of 0’s and 1’s contained in either the CDMA Forward Channel or in
the CDMA Reverse Channel
– Code Channels are characterized (made unique) by mathematical codes
– Code channels in the forward link: Pilot, Sync, Paging and Forward Traffic channels
– Code channels in the reverse link: Access and Reverse Traffic channels
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Main Content
Definitions of CDMA and How to realize
 Spread spectrum modulation
Spreading codes used in CDMA
Vocoding in CDMA
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
What is Spread Spectrum
ORIGINATING SITE
DESTINATION
Spread Data Stream
Input
Data
Recovered
Data
Spreading
Sequence
Spreading
Sequence
Definition:Spread spectrum technique ,employ a transmission bandwidth that is
several orders of magnitude greater than the minimum required signal bandwidth.
Sender combines data with a fast spreading sequence, transmits spread data
stream
Receiver intercepts the stream, uses same spreading sequence to extract
original data
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Spread Spectrum Principles
SHANON Formula
C=B*log2(1+S/N)
Where,
C is capacity of channel, b/s
B is signal bandwidth, Hz
S is average power for signal, W
N is average power for noise, W
It is the basic principle and theory
for spread spectrum communications.
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
How DSSS Spectrum Change
Direct Sequence CDMA
Time
Frequency
User 1
+
=
ZTE University
Code 1
Composite
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
CDMA Is a Spread-Spectrum System
TRADITIONAL COMMUNICATIONS SYSTEM
Spread Spectrum
Narrowband
Signal
Slow
Information
Recovered
Slow
Information
Sent
TX
RX
SPREAD-SPECTRUM SYSTEM
Wideband Signal
Slow
Information
Sent
Slow
Information
Recovered
TX
Fast
Spreading
Sequence
RX
Fast
Spreading
Sequence
 Traditional technologies try to
squeeze the signal into the
minimum required bandwidth
 Direct-Sequence Spread spectrum
systems mix their input data with
a fast spreading sequence and
transmit a wideband signal
 The spreading sequence is
independently regenerated at the
receiver and mixed with the
incoming wideband signal to
recover the original data
Spread Spectrum Payoff:
Processing Gain
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Spread Spectrum Principles
Power is “Spread” Over a Larger Bandwidth
30 KHz
1.25 MHz
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Spread Spectrum Principles
Many code channels are individually
“spread” and then added together to
create a “composite signal”
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Anything We Can Do, We Can Undo
ORIGINATING SITE
DESTINATION
Spread Data Stream
(Base Band + Spreading Sequence)
Recovered
Data
(Base Band)
Input
Data
(Base Band)
Spreading
Sequence
Spreading
Sequence
• Any data bit stream can be combined with a spreading sequence
• The resulting signal can be de-spread and the data stream recovered if the
original spreading sequence is available and properly synchronized
• After de-spreading, the original data stream is recovered intact
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
CDMA Spreading Principle
Using Multiple Codes
ORIGINATING SITE
X+A
DESTINATION
Spread-Spectrum Chip Streams
X+A+B
X+A+B+C
X+A+B
X+A
Input
Data
Recovered
Data
X
X
Spreading Spreading Spreading
Sequence Sequence Sequence
A
B
C
Spreading Spreading Spreading
Sequence Sequence Sequence
C
B
A
• Multiple spreading sequences can be applied in succession and then
reapplied in opposite order to recover the original data stream.
• The spreading sequences can have different desired properties.
• All spreading sequences originally used must be available in proper
synchronization at the recovering destination.
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
“Shipping and Receiving” via CDMA
Mailer
FedEx
Data
Receiving
FedEx
Shipping
Data
Mailer
• Whether in shipping and receiving or in CDMA, packaging is
extremely important!
• Cargo is placed inside “nested” containers for protection and to allow
addressing.
• The shipper packs in a certain order, and the receiver unpacks in the
reverse order.
• CDMA “containers” are spreading codes.
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Main Content
Definitions of CDMA and How to realize
Spread spectrum modulation
 Spreading codes used in CDMA
Vocoding in CDMA
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Spreading Codes in CDMA
Spreading codes selection is the key of spread Spectrum
modulation!
• Spreading code chip speed：1.2288Mc/s；
• Spreading codes used：
Forward link—Walsh code & Short PN
Reverse link—Long PN
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Walsh Code Definition
• The Walsh function is named after Walsh, the mathematician who
proved it an orthogonal function in 1923. It is expressed as Walsh (n,t),
n for the serial number. The CDMA system of IS-95 is differentiated
with the Walsh function.
 Walsh code is an orthogonal square matrix. It is just composed of +1(0)
and –1(1).
0
0
0
0
0
0
0
1
0
1
0
1
0
0
1
1
0
1
1
0
0
H1
ZTE University
H2
Hn Hn
H 2n
=
___
Hn Hn
H4
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Walsh Codes
• 64 Sequences, each 64 chips long
– A chip is a binary digit (0 or 1)
• Each Walsh Code is Orthogonal to all
other Walsh Codes
– This means that it is possible to
recognize and therefore extract a
particular Walsh code from a mixture
of other Walsh codes which are
“filtered out” in the process
– Two same-length binary strings are
orthogonal if the result of XORing
them has the same number of 0s as 1s
EXAMPLE:
Correlation of Walsh Code #23 with Walsh Code #59
#23
#59
XOR
0110100101101001100101101001011001101001011010011001011010010110
0110011010011001100110010110011010011001011001100110011010011001
0000111111110000000011111111000011110000000011111111000000001111
Correlation Results: 32 1’s, 32 0’s: Orthogonal!!
ZTE University
WALSH CODES
#
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
---------------------------------- 64-Chip Sequence -----------------------------------------0000000000000000000000000000000000000000000000000000000000000000
0101010101010101010101010101010101010101010101010101010101010101
0011001100110011001100110011001100110011001100110011001100110011
0110011001100110011001100110011001100110011001100110011001100110
0000111100001111000011110000111100001111000011110000111100001111
0101101001011010010110100101101001011010010110100101101001011010
0011110000111100001111000011110000111100001111000011110000111100
0110100101101001011010010110100101101001011010010110100101101001
0000000011111111000000001111111100000000111111110000000011111111
0101010110101010010101011010101001010101101010100101010110101010
0011001111001100001100111100110000110011110011000011001111001100
0110011010011001011001101001100101100110100110010110011010011001
0000111111110000000011111111000000001111111100000000111111110000
0101101010100101010110101010010101011010101001010101101010100101
0011110011000011001111001100001100111100110000110011110011000011
0110100110010110011010011001011001101001100101100110100110010110
0000000000000000111111111111111100000000000000001111111111111111
0101010101010101101010101010101001010101010101011010101010101010
0011001100110011110011001100110000110011001100111100110011001100
0110011001100110100110011001100101100110011001101001100110011001
0000111100001111111100001111000000001111000011111111000011110000
0101101001011010101001011010010101011010010110101010010110100101
0011110000111100110000111100001100111100001111001100001111000011
0110100101101001100101101001011001101001011010011001011010010110
0000000011111111111111110000000000000000111111111111111100000000
0101010110101010101010100101010101010101101010101010101001010101
0011001111001100110011000011001100110011110011001100110000110011
0110011010011001100110010110011001100110100110011001100101100110
0000111111110000111100000000111100001111111100001111000000001111
0101101010100101101001010101101001011010101001011010010101011010
0011110011000011110000110011110000111100110000111100001100111100
0110100110010110100101100110100101101001100101101001011001101001
0000000000000000000000000000000011111111111111111111111111111111
0101010101010101010101010101010110101010101010101010101010101010
0011001100110011001100110011001111001100110011001100110011001100
0110011001100110011001100110011010011001100110011001100110011001
0000111100001111000011110000111111110000111100001111000011110000
0101101001011010010110100101101010100101101001011010010110100101
0011110000111100001111000011110011000011110000111100001111000011
0110100101101001011010010110100110010110100101101001011010010110
0000000011111111000000001111111111111111000000001111111100000000
0101010110101010010101011010101010101010010101011010101001010101
0011001111001100001100111100110011001100001100111100110000110011
0110011010011001011001101001100110011001011001101001100101100110
0000111111110000000011111111000011110000000011111111000000001111
0101101010100101010110101010010110100101010110101010010101011010
0011110011000011001111001100001111000011001111001100001100111100
0110100110010110011010011001011010010110011010011001011001101001
0000000000000000111111111111111111111111111111110000000000000000
0101010101010101101010101010101010101010101010100101010101010101
0011001100110011110011001100110011001100110011000011001100110011
0110011001100110100110011001100110011001100110010110011001100110
0000111100001111111100001111000011110000111100000000111100001111
0101101001011010101001011010010110100101101001010101101001011010
0011110000111100110000111100001111000011110000110011110000111100
0110100101101001100101101001011010010110100101100110100101101001
0000000011111111111111110000000011111111000000000000000011111111
0101010110101010101010100101010110101010010101010101010110101010
0011001111001100110011000011001111001100001100110011001111001100
0110011010011001100110010110011010011001011001100110011010011001
0000111111110000111100000000111111110000000011110000111111110000
0101101010100101101001010101101010100101010110100101101010100101
0011110011000011110000110011110011000011001111000011110011000011
0110100110010110100101100110100110010110011010010110100110010110
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Walsh Code Table
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
0123
4567
11
8901
1111
2345
1111
6789
2222
0123
2222
4567
2233
8901
3333
2345
3333
6789
4444
0123
4444
4567
4455
8901
5555
2345
5555
6789
6666
0123
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
0000
0101
0011
0110
1111
1010
1100
1001
0000
0101
0011
0110
1111
1010
1100
1001
1111
1010
1100
1001
0000
0101
0011
0110
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Walsh Code Function
in Forward Link
Pilot
Sync
FW Traffic
(for user #1)
FW Traffic
(for user #2)
Paging
FW Traffic
(for user #3)
• A Mobile Station receives a Forward Channel from a sector in a
Base Station.
• The Forward Channel carries a composite signal of up to 64
forward code channels.
• Some code channels are traffic channels and others are overhead
channels.
• A set of 64 mathematical codes is needed to differentiate the 64
possible forward code channels.
– The codes in this set are called “Walsh Codes”
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Short PN: 4-bits register example
p1
p2
p3
p4
p4
p4
p2
p3
p5 = p1 + p4
p4
p5
p2
p3
The PN sequences are deterministic and periodic.
– The length of the generated string is 2n-1, where “n”
is the number of elements in the register
– The number of ones in the sequence are equal to the
ZTE University number of zeros plus 1
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
0
1
0
0
1
1
0
1
0
1
1
1
1
0
0
0
0
1
1
0
1
0
1
1
1
1
0
0
0
1
0
0
0
0
1
1
0
1
0
1
1
1
1
0
0
0
1
0
1
0
0
1
1
0
1
0
1
1
1
1
0
0
0
1
univ.zte.com.cn
Short PN Sequences
The two Short PN Sequences, I and
Q, are 32,768 chips long
• Together, they can be considered
a two-dimensional binary “vector”
with distinct I and Q component
sequences, each 32,768 chips
long
• Each Short PN Sequence (and, as
a matter of fact, any sequence)
correlates with itself perfectly if
compared at a timing offset of 0
chips
• Each Short PN Sequence is
special: Orthogonal to a copy of
itself that has been offset by any
number of chips (other than 0)
32,768 chips long
26 2/3 ms.
(75 repetitions in 2 sec.)
I
Q
Unique Properties:
Short PN Sequence vs. Itself @ 0 Offset
I
Q
I
Q
100% Correlation: All bits = 0
Short PN Sequence vs. Itself @ Any Offset
I
Q
I
Q
Orthogonal: 16,384 1’s + 16,384 0’s
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Short PN Function
in Forward Link
Up to 64
Code Channels
Up to 64
Code Channels
A
B
•
Each Sector in each Base Station is transmitting a Forward Traffic Channel
containing up to 64 forward code channels.
•
A Mobile Station must be able to discriminate between different Sectors of
different Base Stations.
•
Two binary digit sequences called the I and Q Short PN Sequences (or Short PN
Codes) are defined for the purpose of identifying sectors of different base stations.
•
These Short PN Sequences can be used in 512 different ways in a CDMA system.
Each one of them constitutes a mathematical code which can be used to identify a
particular sector.
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Long PN:4-bits
shift register example
Original PN
sequence
XOR
mask
AND
AND
AND
AND
( XOR )
New PN
sequence
0
1
0
0
1
1
0
1
0
1
1
1
1
0
0
0
0
1
1
0
1
0
1
1
1
1
0
0
0
1
0
0
0
0
1
1
0
1
0
1
1
1
1
0
0
0
1
0
1
0
0
1
1
0
1
0
1
1
1
1
0
0
0
1
Attention:different mask lead to different offset!
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
The Long PN Sequence
Long Code Register
(@ 1.2288 MCPS)
AND
1100011000
ESN
=
S UM
Public Long Code Mask
(STATIC)
User Long Code
Sequence
(@1.2288 MCPS)
Modulo-2 Addition
• Each mobile station uses a unique User Long Code Sequence generated by
applying a mask, based on its 32-bit ESN, to the 42-bit Long Code Generator
which was synchronized with the CDMA system during the mobile station
initialization.
• Generated at 1.2288 Mcps, this sequence requires 41 days, 10 hours, 12
minutes and 19.4 seconds to complete.
• Portions of the User Long Codes generated by different mobile stations for
the duration of a call are not exactly orthogonal but are sufficiently different
to permit reliable decoding on the reverse link.
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Long PN Function
in Reverse Link
RV Traffic
from M.S.
#1837732008
RV Traffic
from M.S.
#1997061104
System Access
Attempt by M.S.
#2000071301
(on access channel #1)
ZTE University
RV Traffic
from M.S.
#1994011508
• The CDMA system must be able to identify
each Mobile Station that may attempt to
communicate with a Base Station.
• A very large number of Mobile Stations will
be in the market.
• One binary digit sequence called the Long
PN Sequence (or Long PN Code) is defined
for the purpose of uniquely identifying each
possible reverse code channel.
• This sequence is extremely long and can be
used in trillions of different ways. Each one
of them constitutes a mathematical code
which can be used to identify a particular
user (and is then called a User Long Code)
or a particular “user Reverse Traffic
channel”.
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Main Content
Definitions of CDMA and How to realize
Spread spectrum modulation
Spreading codes used in CDMA
 Vocoding in CDMA
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Variable Rate Vocoding
• CDMA uses a superior Variable Rate Vocoder
– Full rate during speech
– Low rates in speech pauses
– Increased capacity
– More natural sound
• Voice, signaling, and user secondary data may be mixed in CDMA
frames
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
Variable Rate Voice Bit and PCM
•
•
Where is vocoder?
Analog voice
Variable Rate
BTS
ZTE University
BSC
PCM
MSC
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn
ZTE University
The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.
univ.zte.com.cn