WNMP WCDMA
WCDMA Basic Theory
WIRELESS NETWORK MASTER PLANNING
By: Manuel M. Aquino Jr.
Future Access Technologies
Access Network Planning Department
WNMP WCDMA
The Goal of this Course
After this course, you should be able to
• Understand the technology behind
WCDMA and its advantages
• Understand the roots and roadmap
of WCDMA
• Be familiar with the basic
architecture of a WCDMA network
WNMP WCDMA
WCDMA Overview
Advantages of WCDMA
WCDMA Basic Principle
WCDMA Architecture
Content
Training GLOBE TELECOM
WNMP WCDMA
11GG 22GG 33GG 44GG
Analog
cellular DDiiggiittaall cceelllluullaarr DDiiggiittaall cceelllluullaarr Hybrid IP based
VVooiiccee VVooiiccee //ddaattaa VVooiiccee // hhiigghh ssppeeeedd
ddaattaa VVooiiccee // vveerryy hhiigghh
ssppeeeedd ddaattaa
AAMMPPSS
TTAACCSS CCDDMMAA 11XXRRtttt
GGSSMM GGPPRRSS
CCDDMMAA22000000
WCDMA
HSDPA
9.6 Kbps 64 Kbps/144 Kbps 22 MMbbppss >>1100 MMbbppss
8800’’ 11999922 11999999 22000011 22000044 Not yet deployed
Evolution of Mobile Communications
AMPS: Advanced Mobile Phone System
TACS: Total Access Communication System
GPRS: General Packet Radio Services
WNMP WCDMA
Evolution of Mobile Communications
1G – 1st Generation: Analog Cellular
1) Feature:
• frequency division multiple access (FDMA)
• analog signal
• narrow band
2)Main mode: AMPS TACS NMT
3)Limitations:
• hard to develop digital bearer services
• cannot adopt to digitization of fixed networks
• low frequency efficiency
• cannot meet larger capacity requirements
• easy to be eavesdropped
WNMP WCDMA
Evolution of Mobile Communications
2G – 2nd Generation: Digital Cellular
1) Feature:
• time division multiple access (TDMA)
narrow code division multiple access (N-CDMA)
• digital signal, narrow band
• strong anti-interference capability
• security is guaranteed with authentication and encryption
• can support ISDN
2) Main mode: GSM D-AMPS N-CDMA
3)Limitations:
• Narrow bandwidth unable to provide various broadband information services such as high speed data services.
WNMP WCDMA
Evolution of Mobile Communications
3G – 3rd Generation: Digital Cellular – IMT 2000
1) Feature:
• code division multiple access (CDMA)
• digital signal
• broadband
• integrated service system integrating all current mobile telephone system functions providing multiple services
• large capacity
2) meaning of ‘2000’:
• frequency spectrum around 2000MHz
• data rate up to 2000kbps
• putting into business about 2000
3) Main mode: WCDMA CDMA2000 TD-SCDMA
WNMP WCDMA
Evolution of Mobile Communications
4G – 4th Generation: Hybrid IP Based Mobile Network
1) Feature:
• 3G Mobile Voice and Data Service, Broadband
Access, Video Call
• > 10 Mbps Data Rate
• In principle will allow high-quality smooth video
transmission
WNMP WCDMA
Birth of IMT2000
FPLMTS 1985
1996 IMT 2000
Future Public Land Mobile
Telecommunications System
International Mobile
Telecommunications 2000
WCDMA TD-SCDMA CDMA2000 UMTS
3GPP 3GPP2
DECT
WCDMA-UMTS CDMA 2000
WCDMA-FOMA
TDMA
TD-SCDMA
WNMP WCDMA
The Goal of IMT 2000
• Higher transmit rate 2Mbps
• Rich and colorful service
• Good voice quality
• Larger capacity
• Lower cost
• Good security performance
• High frequency efficiency
• Increased Mobility
• Easy to transition from 2G
WNMP WCDMA
Standard Framework of IMT 2000
UIM MT RAN CN CN
UIM-MT
Interface
MT-RAN
Interface
RAN-CN
Interface NNI
Core Networks of other
IMT-2000 family members
WNMP WCDMA
Family concept
3G
standards
CN based on MAP
TD-SCDMA
CN based on MAP
CDMA2000
CN based on ANSI-41
CDMA is the main technology of 3G
WCDMA
WNMP WCDMA
WCDMA
IS-41 CN
GSM GSM CN
NNI
CN(Core Network) 2G/3G Radio Network
WCDMA
IS-95
CDMA2000
Family concept
WNMP WCDMA
3G Standard Organization
WNMP WCDMA
WNMP WCDMA
2Mbps 64kbps
WCDMA
GSM
EDGE
2G 2.5G 3G
9.6kbps
WCDMA Technology Evolution
Wideband Code Division Multiple Access uses direct
sequence spread-spectrum technology to transmit a number of
independent conversations across 5MHz segments of the
radio spectrum.
GPRS
144kbps
2.75G
WNMP WCDMA
UMTS Protocol Version Evolution
R4
R5
R99
• Inherit all the service
and function of
2G(GSM and GPRS)
• CN is composed of
CS domain and PS
domain
• WCDMA UTRAN
access
• Iu interface between
RAN and CN
• Inherit all the service and
function of R99
• CS domain change:
control is separated from
bearer,the function of
MSC can be complete by
split SERVER,MGW
• Voice supported by CS
domain, supporting:
TDM,ATM,IP
• Inherit all the service and
function of R4
• Add IMS domain
• Enhanced IP QoS,
supporting End to End IP
multimedia service
2000 2001 2002 Specification complete time
WNMP WCDMA
MSC TMSC
GGSN
UMTS R99 NETWORK ARCHITECTURE
Node B
Node B
RNC
3G Rel. 99
BTS
BTS
BSC
2G
PSTN/
PLMN SS7oIP
SMSC
HLR
SGSN
MGW
WNMP WCDMA
PSTN/
PLMN
GMSC Server MSC Server
MGW
MGW
HLR MSC TMSC
Node B
Node B
RNC
BTS
BTS
BSC
SGSN
GGSN
3G Rel. 4
2G SS7oIP
IP Backbone
SMSC
UMTS R4 NETWORK ARCHITECTURE
WNMP WCDMA
PSTN/
PLMN
GMSC Server MSC Server
MGW
MGW
MSC TMSC
BTS
BTS
BSC
SGSN
Node B
Node B
RNC
3G Rel. 5
2G
GGSN
SS7oIP
SMSC
IP Backbone
IMS
HLR
UMTS R5 NETWORK ARCHITECTURE
HSS/
HLR
WNMP WCDMA
UMTS
Downlink
Uplink
5 MHz channel FDD mode
Fig. 1
Fig. 2
Uplink and Downlink
5 MHz channel
. . . . . .
TDD mode
Working frequency: 2GHz
Bandwidth: 5MHz
Chip rate: 3.84Mcps
Frame length: 10 ms
WNMP WCDMA
3G Spectrum
WNMP WCDMA
WCDMA Overview
Advantages of WCDMA
WCDMA Basic Principle
WCDMA Architecture
Content
Training GLOBE TELECOM
WNMP WCDMA
Frequency
reuse factor is 1;
network design
and expanding
become much
easier
AMPS, D-AMPS, N-AMPS
CDMA
30 kHz
200 kHz
5 MHz
1
8 Users
100 Users @12.2kbps/user
1
1
1 1
1
1 1
1 1
1
1 1
1
1
1 2
3 4
4
3 2
5 6
1 7
Typical Frequency Reuse N=7
Typical Frequency Reuse N=4
Typical Frequency Reuse N=1
GSM
Advantages of WCDMA(1)
WNMP WCDMA
Large capacity
Power
Power
Power
FDMA
TDMA
CDMA
FDMA---Different user use different
frequency
TACS、AMPS
TDMA---Different user use different
time slot of one frequency
GSM、DAMPS
WCDMA---Different user use same
frequency at the same time,but with
different spreading code
Advantages of WCDMA(2)
WNMP WCDMA
large coverage
almost 2 times than GSM, save money for
operator
Example:cover 1000 km2:
GSM need 200 BTS
WCDMA only need 50 BTS
Attention: exact result need “Link Budget ”
Advantages of WCDMA(3)
WNMP WCDMA
High privacy and hard to eavesdropped
Spread code
Information signal
TX
Demodulated signal
RX
Spread code
Spread signal
Each user is below
the noise deeply
Advantages of WCDMA(4)
WNMP WCDMA
WCDMA:”make before break”---soft handoff
Other systems: “make after break”---hard handoff
Use soft handoff: decrease drop-call rate
Advantages of WCDMA(5)
WNMP WCDMA
Perfect Power Control and voice activation make the UE
Power low, healthy for human body.
Advantages of WCDMA(6)
Mean Power Max Power
GSM: 125mW 2W
WCDMA: 2mW 200mW
WNMP WCDMA
WCDMA Overview
Advantages of WCDMA
WCDMA Basic Principle
WCDMA Architecture
Content
Training GLOBE TELECOM
WNMP WCDMA
WCDMA is a Spread-Spectrum System
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 TRADITIONAL COMMUNICATIONS SYSTEM
Slow Information
Sent
TX
Slow Information Recovered
RX
Narrowband Signal
SPREAD-SPECTRUM SYSTEM
Fast Spreading Sequence
Slow Information
Sent
TX
Slow Information Recovered
RX
Fast Spreading Sequence
Wideband Signal
WNMP WCDMA
What is Spread Spectrum?
ORIGINATING SITE DESTINATION
Spreading Sequence
Spreading Sequence
Input Data
Recovered Data
Spread Data Stream
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
Spread signal
WNMP WCDMA
-1 1 1 -1 1 Spreading
-1 1
1 -1 1 -1
Spread Process
Digital Signal Spreading Signal
Spreading Code
1 -1 -1
WNMP WCDMA
-1 1 -1 1 -1 -1 1 1 -1 -1 1 1 -1 1 -1 1 De-
spreading
-1 1 -1 1 -1 -1 1 1
1 -1 1 -1
1 1 1 1
Integrator -4 4
0 0
Adjudge -1 1
De-spread Process
WNMP WCDMA
Illustration to SS Principle(1)
5 MHz
12.2 KHz
Power is “Spread” Over a Larger Bandwidth
WNMP WCDMA
Many code channels are individually
“spread” and then added together to
create a “composite signal”
Illustration to SS Principle(2)
WNMP WCDMA
Spread Spectrum Principles
Shannon's 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
N is average power for noise
In 1948 Claude Shannon published his landmark paper on information theory. A Mathematical Theory of Communication. His paper so clearly established the foundations of information theory that his framework and terminology are standard today. He died February 4, 2001 at age 84.
WNMP WCDMA
Multiple Access
• Types of Media:
– 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
– Easier to manage and administer
Each pair of user
enjoys a dedicated,
private circuit through
the transmission
medium, unaware that
the other users exist.
Since the beginning of telephony and radio,
system operators have tried to squeeze the
maximum amount of traffic over each circuit.
Multiple Access: Simultaneous private use of a transmission medium by multiple independent users.
Transmission
Medium
WNMP WCDMA
Channels
• 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
Power
Power
Power
FDMA
TDMA
CDMA
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.
WNMP WCDMA
Physical Channels(1)
The physical channel is in a 3-layer structure by the time: – Superframe
One superframe lasts 720ms, and consists of 72 radio frames.
– radio frame
One radio frame has a period of 10ms, and comprises 15
timeslots with the same length. Corresponding to 38400
chips, it is a basic unit of the physical layer.
– Timeslot
A timeslot is a unit composed of a bit domain, corresponding
to 2560 chips. The bit number and structure of a timeslot
depends on the specific type of the physical channel.
WNMP WCDMA
Physical Channels(2)
• The frame structure of the physical channels is shown:
Tslot #1 Tslot #2 Tslot #I Tslot #15
Tslot= 2560 chip
Frame #0 Frame #1 Frame #I Frame #71
Tf=10 ms
Tsuper=720 ms
WNMP WCDMA
Key Technologies of WCDMA
• Power Control
• Handover Control
• Rake receiving
WNMP WCDMA
Why Power Control?
• All WCDMA users occupy the same frequency at the same time! Frequency and time are not used as discriminators.
• WCDMA operates by using CODES to discriminate between users.
• WCDMA interference comes mainly from nearby users
• Each user is a small voice in a roaring crowd -- but with a uniquely recoverable code.
Transmit power on all users must be tightly controlled
so their signals reach the base station at the same signal level
and at the absolute minimum power level necessary to ensure
acceptable service quality.
WNMP WCDMA
Power Control
Overcome Near-Far effect and fading compensation
ensuing network capacity
DL power control
Cell transmitting
power
Transmitting power control bit
UE signal
Power control
order
UL power control
WNMP WCDMA
Near-Far Effect
Power
f
Power
f
Nearby terminals have higher probability of success
Power control reduce the
interference among each UEs
and increase system capacity
WNMP WCDMA
3 methods of power control
Open loop: measure received signal level and
adjust transmitting power
Inner-loop: frequency 1500HZ
Measured SIR> Target SIR, lower
transmitting power
Measured SIR< Target SIR, increase
transmitting power
Outer-loop: measure FER, adjust target SIR
WNMP WCDMA
Power control
UE
RNC
Node B
Open loop power control(no feedback)
Closed loop power control(feedback)
UE Node B
RNC
Outer-loop Inner-loop
WNMP WCDMA
Power control
If received signal is stronger,then
UE can transmit lower
Node
B Node
B
1
2
1
2
PROBLEM
Assumes same exact path loss in both directions; therefore, cannot
account for asymmetrical path loss
Estimates are based on total power received
Open loop
If received signal is weaker,then UE
can transmit stronger
WNMP WCDMA
Power control
Inner-loop power control is fast
Inner-loop :according to SIR estimation,Node-B control UE transmission
power.conducted every 0.66ms (1500Hz )
Outer-loop: according to FER measurement estimation RNC control and
adjust SIR target
Node
B
...
”Power down”
”Power up”
”Power down”
”Power ...”
SIR estimation
SIR
estimation
SIR
estimation
SIR estimation RNC SIR
target
WNMP WCDMA
The Effect of Power Control
The purpose of DL power control: Saving power resource of base station, reducing
interference to other station.
The purpose of UL power control: Overcoming Near-Far effect, received signal level
from all UEs is the same.
WNMP WCDMA
WCDMA Handoffs
During
a Call
Idle Handoff
Soft Handoff
Softer Handoff
Hard Handoff
While in the
Idle State
WNMP WCDMA
Soft/Softer Hand-off
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
WNMP WCDMA
Soft/Softer Hand-off
• The soft/softer handover allows to swap from one cell to another
without call interruption or without deleting all old radio links (by
opposition to hard HO).
• It also allows the UE to be connected to more than one cell
simultaneously.
Soft Handover Softer Handover
CN CN
Iur
The two Node Bs may belong to the
same RNC
The two Node Bs may belong to the
same RNC
Soft Handover Softer Handover
SRNC DRNC
CN
Node B
SRNC
CN
Soft Handover Softer Handover
Node B
CN
WNMP WCDMA
Hard Hand-off
• The hard handover procedure is used in case of
service quality degradation or for traffic distribution
management.
• During the hard handover procedure, all the old
radio links with the UE are abandoned before new
ones are established.
• Hard handover may occur in the following
main cases :
• When the UE is handed over another UTRAN
carrier, or technology or mode.
• When soft handover is not permitted (if O&M
constraint)
Hard Handover
Node B
SRNC
RNC or
BSC
CN
Node B
or BTS
WNMP WCDMA
Traffic control
• When traffic surpass system
threshold, traffic control
begin
• To accept as many services as
possible while keeping the
stability of the system.
WNMP WCDMA
Example for load control
• Breath effect of cell
– With the increase of activated
terminals, interference increase
– the increase of high speed service,
the increase of interference
– The shrink of cell coverage area
– Coverage blind spot occurs
– Drop of call will happen at the edge of cell
Coverage and capacity are
relative
WNMP WCDMA
Multipath Propagation
Received Signal
Time
Strength
0
Transmit
WNMP WCDMA
RAKE Receiving
d1 d2
t t t
d3
transmitting Receiving Rake
combination noise
WNMP WCDMA
RAKE Receiving
RAKE overcome multi-finger interference,improve receive capability
receiver
Single
receiving
Single
receiving
Single
receiving
searcher calculate
combining
t t
s(t) s(t)
signal
WNMP WCDMA
Coverage/capacity vs Data Rate
>12.2 kbps
>64 kbps
>384 kbps
>144 kbps
Coverage decrease
Subscriber
num
increase
Higher rate needs higher power
High data rate transmission is only available nearby the station
WNMP WCDMA
Characteristic of WCDMA system capacity
WNMP WCDMA
Coverage and Capacity
WCDMA performance is determined by such factors as: – Number of users
– Transmission rate
– Mobile rate
– Wireless enviroment
• indoors
• outdoors
The sizes of cell depend on such factors as: – Local radio conditions (local interference)
– Traffic in neighbouring cells (distanced interference)
Cell Radius decrease according to the increase number of users
WNMP WCDMA
WCDMA Overview
WCDMA Basic Principle
Advantages of WCDMA
WCDMA Architecture
Content
Training GLOBE TELECOM
WNMP WCDMA
WCDMA Architecture
Iu
Iur
RNC
RNC: Radio
Network
Controller SGSN
GGSN
AuC HLR EIR
VLR
G-MSC
MSC
ce
ll ce
ll cell
ce
ll cell
ce
ll ce
ll ce
ll ce
ll
Uu
US
IM
US
IM
US
IM
FDD mode
only
UE: User
Equipment No
de B
N
od
e B
N
od
e B
RNS: Radio Network Subsystem
RNS
CN: Core Network
IuCS
IuPS Iub
G
c
Gr
Gs Gf
D
B
F C
PSTN
E E
Gi
Gn
Gp
ME
ME
ME
WNMP WCDMA
UTRAN Structure
Node B
Node B
Node B
Node B
RNC
RNC
MSC/
VLR
SGSN
U
E
U
E
IuUu
UTRANCN
Iub
RNS
RNS
Iur
WNMP WCDMA
WCDMA Architecture
• The system consists of:
– UTRAN
UTRAN performs all the functions related to wireless
communication;
– CN (Core Network)
CN switches and routes voice and data services to
connect them to the external network.
The UE (User Equipment) is connected to the
UTRAN through the air interface standard.
WNMP WCDMA
Functional Units
• UE (User Equipment):
As the wireless terminal that performs wireless
communication via the Uu interface, it contains an intelligent
card, which records the user ID, performs the authentication
algorithm, and stores information such as authentication
information and keys.
• Node B:
Transmits data streams between the Iub and the Uu
interfaces, participating in radio resource management.
WNMP WCDMA
Functional Units
• RNC (Radio Network Controller): Owns and controls the radio resources under its
administration. The RNC is the service access point
provided by the UTRAN for the CN.
• HLR (Home Location Register):
It is a database located at the local system of the user,
used to store the subscriber service features. Such features
include information of the services allowed, roaming
areas and information of value-added services.
WNMP WCDMA
Functional Units
• MSC (Mobile Switching Center) /VLR (Visit
Location Register):
The MSC processes circuit switched services, while the VLR stores a copy of the service feature description of the roaming subscribers, and more accurate information of the location of the UE in the service system.
The network part connected through the MSC/VLR is usually referred to as the CS domain.
WNMP WCDMA
Functional Units
• GMSC (Gateway Mobile-services Switching Center):
It is the switching equipment at the connection between the
UMTS network and the external circuit domain network. All incoming/outgoing CS connections go through the GMSC.
• SGSN (Serving GPRS Support Node):
Its function is similar to that of the MSC/VLR, except that
it is used for Packet Switched (PS) services. The network part connected through the SGSN is referred to as the PS domain.
• GGSN (Gateway GPRS Support Node):
Its function is similar to GMSC, but it is related to PS services.
WNMP WCDMA
Functional Units
External networks fall into two groups:
1. CS network:
It provides circuit switched connections, such as
the existing telephone services. Both ISDN and PSTN
are CS networks.
2. PS network:
It provides packet switched connections. The
Internet is an example of the PS network.
WNMP WCDMA
NE Interfaces
• Uu interface:
Serves as the air interface of the WCDMA system to
connect a UE to a Node B.
• Iu interface:
Connects the UTRAN and the CN. It is similar to the A interface (circuit switching) and the Gb interface (packet switching) in GSM.
• Iur interface:
Allows soft handover between the RNC equipment of different manufacturers as an open interface.
• Iub interface:
Connects the Node B and the RNC.
WNMP WCDMA
Brief Introduction to Node B
RNS RNS
NodeB NodeB NodeB NodeB
RNC
CN
RNC
Iu Iu
Iur
Iub Iub Iub Iub
UE
Uu
WNMP WCDMA
Brief Introduction to RNC
SRNS DRNS
NodeB NodeB NodeB NodeB
RNC
CN
RNC
Iu Iu
Iur
Iub Iub Iub Iub
UE Uu
S-RNC: Serving Radio Network Controller
D-RNC: Drifting RNC
WNMP WCDMA
Thank You
WNMP WCDMA
MSC RNC NODE B SECTOR VOCODER CARRIER TYPE of Handoff
S S S D S S Softer
S S S D S D Hard
S S D D S S Soft
S D D D D S Hard
S D D D S S Soft
S D D D D D Hard
Handoff Description
Support Slide for Handoff