CDMA System Basis
ZTE 中兴 CDMA
Features of Wireless Telecomm
 Individually
 Bad propagation environment
 Co-channel, Adjacent channel interference
and near-far effect.
 Contradiction between limited frequency
resource and vast numbers of subscribers.
 Complicated network and control
equipment are required.
ZTE 中兴 CDMA
Classification of Wireless
Telecomm
Classification
Mode
RF Operation
Class
Simplex, half-duplex, duplex
Signal
Analog, Digital
Modulation
FM, PM, AM
Multiple
Access
FDMA, TDMA, CDMA
ZTE 中兴 CDMA
ZTE 中兴 CDMA
Frequency Reuse
ZTE 中兴 CDMA
Evolution of Wireless Telecomm
1G
2G
3G
Analog
Digital
Digital
Voice
Voice & Data
AMPS
CDMA
Voice &
high-speed
Data
CDMA2000
TACS GSM/TDMA GPRS
W_CDMA
1980’s
20 01 20 0 3
19 92
19 99
ZTE 中兴 CDMA
Makeup of Wireless Telecomm
BSS
MS
BTS
MS
BTS
BTS
BSC
VLR
HLR
MSC
PSTN
MS
ISDN
BTS
BTS
BTS
MS
Um
Abis
BSC
A
MS: Mobile Station
BSS: Base Station
System
BTS: Base-station
Transceiver System
BSC: Base_Station
Controller
MSC:Mobile-service
Switching Center
VLR:Visiting Location
Register
HLR:Home Location
Register
PSTN:
ISDN:
MSC
ZTE 中兴 CDMA
Spectrum Spreading Technique
 Theoretical Basis is Shanon equation
C=B*log2(1+S/N)
 DSSS applied in CDMA
 Used in military communication in 1950’s
and 1960’s
 Qualcomm company successfully put it
into commercially cellular wireless
telecommunication by the end of 1980’s
ZTE 中兴 CDMA
Signal processing by DSSS
ZTE 中兴 CDMA
Features of CDMA System（1）
 Large capacity
8~10 times of analog system
 High-quality service
8Kb/s QCELP EQUALS 13Kb/s of GSM;
13Kb/s QCELP EQUALS 64kb/s of wireline
 Soft handoff lowers call drop rate
 RAKE receiving overcomes multi-path
fading
 Good secrecy
ZTE 中兴 CDMA
Features of CDMA System （2）
 Soft capacity
 MS’s averaging transmission power is
lowered, decreasing radiation to human
body and environment . Be named as
“Green Handset”
 Easy to realize dual-mode operation
 System complexity increased
ZTE 中兴 CDMA
Key techniques of CDMA （1）

Diversity receiving
Time diversity——interleaving, error-detection
and correction
Frequency diversity——inherent feature of
wideband communication
Space diversity——multiple antenna receiving,
RAKE receiving, soft handoff
ZTE 中兴 CDMA
Key techniques of CDMA （2）
 Precise power control
Open loop power control on reverse link
Closed loop power control on reverse link
Outer loop power control on reverse link
Power control on forward link
ZTE 中兴 CDMA
Key techniques of CDMA （3）
 Rate variable codec (QCELP)
 VOICE Detection (VOD)
 Synchronization
 Mobile assisted soft handoff
ZTE 中兴 CDMA
Key techniques of CDMA （4）
 Blossoming & Wilting
 Low Eb/No and high redundant error
correction encoding
 Multiple access：long PN code, short PN
code and WALSH orthogonal code
ZTE 中兴 CDMA
Channel structure
 Forward Channels
Piloting channel
Synchronizing channel
Paging channel
Traffic channel
 Reverse Channels
Access channel
Traffic channel
ZTE 中兴 CDMA
CDMA Cell Sit e
Pilo t
Forw ard
Traf fic Channel

Sync
Forw ard Traf fic
Channel
Paging
Forward Traff ic
Channel
Walsh Code Assignment
0 -> Pilot
32 -> Sync
1-7 -> Paging(s)
rem. -> Fwd. Traffic
ZTE 中兴 CDMA
IS-95A Channel Modulation--Forward Link
Wal sh
Function 0
Pil ot
Channel
(Al l 0’s)
Sync
Channel
Bi ts
A
1.2 kbps
Convol uti onal
Encoder
r = 1/2, K = 9
Code
Symbol
Modulation
Symbol
Symbol
Repeti ti on
2.4 ksps
4.8 ksps
Code
Symbol
Pagi ng
Channel
Bi ts
9.6 kbps
4.8 kbps
Convol uti onal
Encoder
r = 1/2, K = 9
Bl ock
Interl eaver
Modulation
Symbol
19.2 ksps
9.6 ksps
Symbol
Repeti ti on
19.2 ksps
Wal sh
Function 32
Modulation
Symbol
A
4.8 ksps
Wal sh
Function p
Modulation
Symbol
Bl ock
Interl eaver
A
19.2 ksps
19.2 ksps
Long Code
Mask for
Pagi ng
Channel p
Forward Traffi c
Channel code
channel
Informati on
Bi ts for User m
wi th Rate Set 1
(172, 80, 40, or
16 bi ts/frame)
8.6
4.0
2.0
0.8
kbps
kbps
kbps
kbps
Add Frame
Quali ty Indicators (12, 8, 0, or
0 bi ts/frame)
Add 8-bi t
Encoder Tail
per Frame
9.6
4.8
2.4
1.2
Long Code
Generator
1.2288 Mcps
Code
Symbol
Convol uti onal
Encoder
kbps r = 1/2, K = 9 19.2 ksps
kbps
9.6 ksps
kbps
4.8 ksps
kbps
2.4 ksps
Decimator
Modulation
Symbol
Symbol
Repeti ti on
19.2 ksps
Wal sh
Function n
800 bps
Power
Control
Bi ts
Modulation
Symbol
MUX*
A
Bl ock
Interl eaver 19.2 ksps
19.2 ksps
Long Code
Mask for
User m
Long Code
Generator
1.2288 Mcps
Decimator
800 Hz
Decimator
* Power control bits are not multipl exed in for suppemental code channel s of
the Forward Traffi c Channel s
ZTE 中兴 CDMA
Procedure of MS’s COMMUNICATION
 Searching base station’s pilot channel
 Demodulating synchronizing channel
 MS requests on access channel
 BS responds on paging channel
 Traffic channel is assigned for
communication
ZTE 中兴 CDMA
Task Initialization
Start analog mode
End analog mode
MS idle changeover
when
NGHBR_CONFIG
is”011”
Power On
MS
Initial
Status
MS fully catches
System timing
MS idle
status
MS paged,
originating or
registering
Access channel
confirmation
System
access
status
End traffic channel
Indication of traffic
channel
Notes：not all are listed out
MS in traffic
Channel
status
ZTE 中兴 CDMA
ZXC10-BSS System structure-BSC
BSC: Base_Station Controller
BTS:
Base-station
Transceiver
System
NCM: Network Control Module
HIRS:
High-speed
Interconnect
Router Subsystem
CDSU: Channel/Digital Service Unit
TCM: Timing Control Module
SVM: Selector Vocoder Module
SVICM: Selector Vocoder Interface
Control Module
CPM: Call Process Module
OMC: Operation & Maintenance
Center
ZTE 中兴 CDMA
ZXC10-BSS System structure-BTS
Gps or
Glonass
TCM
TRx
HPA
RFE
RFIM
CHM
CHM
CHM
BTS
...
HIRS
CCM
BTM
BTS: Base-station Transceiver System
CHM: Channel Processing Module
CCM: Communication Control Module
HIRS: High-speed Interconnect
Subsystem
TCM: Timing Control Module
RFIM: RF Interface Module
TRx: Transceiver
HPA: High Power Amplifier
RFE: RF Front End
CDSU: Channel/Digital Service Unit
BTM: Base-station Test Module
BSC: Base-station Controller
Router
CDSU
ATM or E1
Other BTS
BSC
ZTE 中兴 CDMA
ZXC10_BSS System
Specification-BSC








Maximal BTS supported: 512
Vocoder：7200
Maximal Channels (including payoff and soft handoff):512 X 32 = 16384
Maximal traffic channels: 512 X 20 = 10240
Maximal subscribers: 102,500*
BTS side traffic：2,930 Erl*
BHCA：125,000*
Traffic：1.28BHCA/subscriber
ZTE 中兴 CDMA
ZXC-10 BSS-transition to 3G
IS95 A
Features:
IS95 B


Capacity
increased
Non-symmetrical
data service
provided



For:64Kb/s
Rev:14.4Kb/s
Backward
compatible with
95A
CDMA2000 1X



CDMA2000 3X
Capacity doubled  Data service
(relative to 95A)
 384Kb/s
 2Mb/s(max)
Data service
 144Kb/s
 Backward
compatible with
 307.2Kb/s(max)
95A/B/1X
Backward
compatible with
95A/B
ZTE 中兴 CDMA