Date post: | 03-Jun-2018 |
Category: |
Documents |
Upload: | ashit-singh |
View: | 227 times |
Download: | 0 times |
of 44
8/12/2019 UMTS Basic Principle
1/44
Section 4
W-CDMA Principles
8/12/2019 UMTS Basic Principle
2/44
The Spread Spectrum Principle
The Channelization codes & Scrambling codes. Their main properties
The importance of Eb/No
The concept of Power Control
The coverage limits
The Rake Receiver
The macro-diversity
Handovers
Objectives
At the end of this session, you will be able to:
W-CDMA Principles
8/12/2019 UMTS Basic Principle
3/44
Power
PowerPower
FDMA TDMA
W-CDMA
Dedicated Channel: An indiv idual ly-assigned, dedicated pathway
through a transm ission medium
for one users information
Access Technologies
8/12/2019 UMTS Basic Principle
4/44
Je parle franais Ich spreche
deutsch
I speak
english
PARLO ITAL IANO!
Access Technologies
Analogy with the W-CDMA
8/12/2019 UMTS Basic Principle
5/44
Duplex Spacing: 190 MHz
FDD
Time
Frequency
Power
5 MHz 5 MHz
Code Multiplex
UL DL
UMTS USER 1
UMTS USER 2
Time
Frequency
Power
TDD
5 MHz
Code Multiplex
&
Time Division
666.67 s
DL
UL
DL
DL
UL
UMTS USER 2
UMTS USER 1
Access Technologies
W-CDMA: FDD or TDD
8/12/2019 UMTS Basic Principle
6/44
Binary data to transmit 0 1 0 0 1 0
The faster is the bit rate, the more the energy is spread on the spectrum
+ a
- a
a2T0
s(t)
T0
1/T0 2/T0Frequency
Time
0 1 0 0 1 0
+ a
- a
a2T1
s(t)
T1
1/T1 2/T1Frequency
NRZ
coding
Time
0 1 0 0 1 0
Power
spectrum
Spread Spectrum Principle
1 - Time - Frequency Duality
8/12/2019 UMTS Basic Principle
7/44
Tbit
Tchip
Data sequence
spreading sequence
transmitted sequence
a2Tbit = Ebit
1/Tbit
Tchip = Echip
1/Tchip
Frequency
a2Tchip
1/Tchip
+a
-a
-1
+1
-a
+a
x
=
Data
sequenceTransmitted
signal
Spreading sequence generator
Modulation
x(t)Power spectrum
Spread Spectrum Principle
2 - Transmission
8/12/2019 UMTS Basic Principle
8/44
Tbit
Tchip
Data sequence
spreading sequence
received sequence
a2Tbit = Ebit
Power spectrum
1/Tbit
Tchip = Echip
1/Tchip
Frequency
a2Tchip+a
-a
-1
+1
-a
+a
x
=
1/Tchip
Received
signal
Data
sequence
Spreading sequence generator
Demodulation
x(t)
Spread Spectrum Principle
3 - Reception
8/12/2019 UMTS Basic Principle
9/44
Spread Spectrum Principle
4 - Code Multiplexing
Power spectrum
User 1
User 2
User 3
User 4
User 5
Spreading
Code 1
Code 2
Code 3
Code 4
Code 5
Composite signal
5 MHzCodes discriminate users
8/12/2019 UMTS Basic Principle
10/44
Unwanted Power
from other sources
Using the right mathematical sequences
any Code Channel can be extracted
from the received composite signal
Spread Spectrum Principle
5 - Extraction
8/12/2019 UMTS Basic Principle
11/44
Scrambling code
Channelization code 1
Channelization code 2
Channelization code 3
User 1 signal
User 2 signal
User 3 signal
BTS
Codes Multiplexing
1 - Downlink Transmission on a Cell Level
8/12/2019 UMTS Basic Principle
12/44
BTS
Scrambling code 3
User 3 signal
Channelization code
Scrambling code 2
User 2 signal
Channelization code
Scrambling code 1
User 1 signal
Channelization code
Codes Multiplexing2 - Uplink Transmission on a Cell Level
8/12/2019 UMTS Basic Principle
13/44
Cch,1,0=1
Cch,2,0=1 1
Cch,4,0=1 11 1
Cch,4,1=1 1-1 -1
Cch,2,1=1 -1
Cch,4,2=1 -1 1 -1
Cch,4,3=1 -1-1 1
SF = 1 SF = 2 SF = 4 SF = 8 SF = 16, 32, 64, 128, 256, 512
Cch,2,0=1 1
Cch,2,1=1 -1
Cch,4,0=1 1 1 1
Cch,4,1=1 1 -1 -1
Cch,4,2=1 -1 1 -1
Cch,4,3=1 -1 -1 1
Channelization Codes - OVSFOrthogonal Variable Spreading Factor: code tree generator
8/12/2019 UMTS Basic Principle
14/44
+
-1 -1 -1
-1 -1 -1 -1
1 1 1 1
1 1 1 1
-1
*
1 1 1 1-1 -1 -1 -1
Cj
Ck
T0 synchronization
= 0+
-1 -1 -1
-1 -1 -1 -1
1 1 1 1
1 1 1 1
-1
*
1 1 1 11 -1 1 -1
Cj
Ck
no T0 synchronization
= 4
=> Orthogonal => Non orthogonal
No correlation Small correlation
Channelization Codes - OVSF
Orthogonality
8/12/2019 UMTS Basic Principle
15/44
Physical Layer Structure
Frame #0 Frame #1 Frame #i Frame #4095
System frame = 4096 frames = 40.96 seconds
Slot #0 Slot #1 Slot #j Slot #14
Frame= 15 slots = 10 ms = 38400 chips
Slot= 0.667 ms = 2560 chips
Data or control or mixed: 10*2kbits, k from 0 to 6 (UL), from 0 to 7 (DL)
UMTS Frame Format
8/12/2019 UMTS Basic Principle
16/44
A Tapped, Summing Shift Register
Sequence repeats every 2N-1chips,
where N is number of cells in register
Scrambling Codes
Scrambling codes Properties:
38 400 chip long sequences
Repeated every 10 ms
Issued form Pseudo Noise sequences
8/12/2019 UMTS Basic Principle
17/44
Scrambling Codes Properties
Auto Correlation
Synchronized
=> Complete Correlation
Shifted
=> Almost Orthogonal
Almost orhtogonal
Cross Correlation
Random delay
8/12/2019 UMTS Basic Principle
18/44
Uplink Scrambling Codes
Total of 224long scrambling codesof 38,400 chips
225-1 chip longsequences
X25+ X3+ 1
X25+ X3+ X2+ X + 1
I
Q
8/12/2019 UMTS Basic Principle
19/44
Downlink Scrambling Codes
8192scrambling
codes
512 sets of 1primary and 15
secondarycodes
512 primarycodes dividedinto 64 groups
Possibility of 262,143 different downlink scrambling codes
Only 8192 different scrambling codes have been defined
8192 ...
Cell #1
Cell #512
...
Primary scrambling code
Secondary scrambling code #1
Secondary scrambling code #2
Secondary scrambling code #15
8/12/2019 UMTS Basic Principle
20/44
Exercise
UE1
How do UE1and UE2get them bits?
8/12/2019 UMTS Basic Principle
21/44
Channelization Codes Multiplexing
-11User 1
User 2
Code 1: Cch(SF= )
Code 2: Cch (SF= )
1-11 1-11
=
+
*
*
=
=2
-2
0
1
1-1 -1 1 1 1 -1-1
1 -1-11
-1
-1
UsersComposite
Signal
1
1
8/12/2019 UMTS Basic Principle
22/44
Scrambling code
Users CompositeSignal
Scrambling
Code
*
2
0
-2
2
0
-2
=
1
-1
TransmittedSignal
8/12/2019 UMTS Basic Principle
23/44
Radio Interferences2
0
-2
Transmitted
Signal
0
0
Noise
ReceivedSignal =
1
-1
1
-1
+
8/12/2019 UMTS Basic Principle
24/44
UE1: Reception & Decoding
0
Received
Signal
1
-1
1
-1
1
-1
Scrambling Code
Channelization Code
Data
Extraction
*
*
8/12/2019 UMTS Basic Principle
25/44
UE2: Reception & Decoding
0
Received
Signal
1
-1
1
-1
1
-1
Scrambling Code
Channelization Code
Data
Extraction
*
*
8/12/2019 UMTS Basic Principle
26/44
Basic W-CDMA Elements
C
I
N
C
CEb/No
1 - Eb/NoW-CDMATDMA-GSM
Power spectrum
1
1
11
1
1
1
2
2
2
2
3
3
3
3
3
2
4
4
4
4
4
8/12/2019 UMTS Basic Principle
27/44
Maximum noise level
Eb/No
required
Basic W-CDMA Elements
Power spectrum
a2Tbit = Ebit
gain
Unwanted power
from other sources
2 - Eb/No
Echip
Eb / No = C / I x processing gain
Available power to share
between users
8/12/2019 UMTS Basic Principle
28/44
a2Tbit = Ebit
Power spectrum
Maximum noise level
Eb/No
required
Unwanted power
from other sources
Eb/No
Powercontrol
Power , Interference , Capacity .
Basic W-CDMA Elements
Eb/No & Power Control
8/12/2019 UMTS Basic Principle
29/44
Power Control
1 - Open Loop
MS Access Pre Amble #1 with estimated power
MS Access Pre Amble #n with increased power
RNS Response with Power Control
MS Access Pre Amble #2 with increased power
8/12/2019 UMTS Basic Principle
30/44
Power ControlClosed Loop (Uplink)
Inner Loop
Outer Loop
Service => QoS
RNC setsSIR target for service
Iub
BTS sendsPower Control bitsto UE(1500 times/second)
MS Tx
RNC sends new SIR target
BS continues Power Control
RNC calculatesBLER for Tx
BTS transmits the received blocks
RNC receives a Service Request
8/12/2019 UMTS Basic Principle
31/44
Interference level
Example: 2 UEs at thesame distance from theBTS using 2 data rates
Eb/No
require
d
SF
=
128
Service provided: Speech
Interference level
Eb/No
required
Service provided: Data 144
User 2 needs more power for theUL & DL for the same quality as
user 1
BTS
Received powerReceived power
Coverage Limits (1)
UE2UE1
Speech 8 kbps Data 144 kbpsThe higher the SF, the less power required
8/12/2019 UMTS Basic Principle
32/44
SF = 128
Speech 8 kbps Data 64 kbps Data 384 kbps
BTS
SF = 32
SF = 4
Coverage Limits (2)
The coverage limits are determined by
the Uplink link Budget
8/12/2019 UMTS Basic Principle
33/44
Radio Resource Management
Mapping between demanded QoS, subscription type and allocated QoS
RAB QoS attri butesTraffic class
Maximum bitrate
Guaranteed bit rate
Delivery order
Maximum SDU size
SDU error ratio
Residual bit error ratio
Delivery of erroneous SDUs
Transfer delay
Traffic handling priority
Pre-emption Capability
Pre-emption Vulnerability
Queueing
Allocation/Retention
Priority(ARP)
(User Type)
Traffic Class
Traffic Handlingpriority(THP)
(Service Type)
MAC logical channel prioritySRB > C > S > I > B
Iub/Iur
Allocation/Retention Priority
Iub/IurFrame Handling Priority
Scheduling Priority Indicator
Common Transport Channel Priority Indicator
DCH/HSPA/MBMS
(Bearer Type)Scheduling Priority
Data Rate Application Priortiy
+
+
+
Basic Priority
Diff t T Of P i it
8/12/2019 UMTS Basic Principle
34/44
Different Type Of Priority
Priority Function Case
Basic Priority Admission Control
HSDPA Schedule
HSUPA Schedule
(1).In case of admission control, RNC get AC thresholdthrough BP; so when cell load is high, high priority user
can be granted, while low priority user will be rejected.
(2) For HSDPA Service, when there is multiple users,
NODEB will allocate code and DL power based SPI
(associated with BP)
(3) For HSUPA ,when there are multiple users, NODEB
will allocate power grant based SPI (associated with BP).
SP of RNC Congestion Control (1)When cell is congestion, and user was pre-emption, RNC willselect user according to the SP
(2) When cell is congestion ,and user was queued, RNC will select
user in queue to execute Admission control according the SP
Application
Priority
Congestion Control
OverLoad Control
(1)When cell is congestion ,and trigger downgrade ,RNC will select
user to downgrade rate according the AP.
(2) When cell is overloaded , RNC will select user to do someaction , so the load can be down.
U li k Li it (1)
8/12/2019 UMTS Basic Principle
35/44
UE2
UE3
UE2 UE3
BS Receiver
BTS
Maximum Noise Floor
Lowest Despread SignalEb/No
ProcessingGain
Uplink Limits (1)
UE1
Receiver sensitivityUE1
U li k Li it (2)
8/12/2019 UMTS Basic Principle
36/44
Receiver sensitivity
BS Receiver
Maximum Noise Floor
Lowest Despread Signal
BTS
Cell Breathing
Eb/No
ProcessingGain
UE2 UE3
Eb/No
ProcessingGain
UE1 UE4
The more loaded the cell, the smaller the cell.
Uplink Limits (2)
UE4
C it Li it (1)
8/12/2019 UMTS Basic Principle
37/44
BS Power Amplifier
50 W
0 W
BTS
BTS
UE1 UE2 UE3 UE4
Capacity Limits (1)
UE1
UE2
UE3
Capacity Limits (2)
8/12/2019 UMTS Basic Principle
38/44
UE2 UE3UE1
BS Power Amplifier
50 W
0 W
UE4
BTS
BTS
Capacity Limits (2)
Rake Receiver
8/12/2019 UMTS Basic Principle
39/44
TX
D(t)
Delay 0
Delay 1
C(t-0)
+C(t-1)
Delay (1)
RX
C(t-n)
Delay (0)
Delay (n)RX
RX
C(t)
0
1
n
Take advantage ofmultipath diversity
BTS
Rake Receiver
UE
Spreading &Scrambling
Macro Diversity
8/12/2019 UMTS Basic Principle
40/44
Macro-Diversity
Softer Hand Over
Node B(BTS)
RNC
Data UL
Data UL1Data UL2 Data UL
Data UL
Data DLData DL
Data DL1
Data DL1
Data DL2
Data DL
UE
Data DL2
Data UL
Core
Network
Macro Diversity
8/12/2019 UMTS Basic Principle
41/44
Macro-Diversity
Soft Hand Over Intra RNC
RNC
Data UL1
Data UL1Data UL2
Data UL
Data UL
Data DL
Data DL1
Data DL1
Data DL1Data DL2 Data DL
UE
Core
Network
Data DL2
Data UL
Data DL2
Data UL2
Data UL2
Data UL1
Node B(BTS)
Node B(BTS)
Macro-Diversity
8/12/2019 UMTS Basic Principle
42/44
Macro Diversity
Soft Hand Over Inter RNC: Serving RNC (SRNC) and Drift RNC (DRNC)
Node B(BTS)
SRNC
DRNCNode B(BTS)
Data UL
Data UL
Data ULData UL1
Data UL2
Data UL2
Data UL1Data UL2 Data UL
Data UL
Data DLData DL2
Data DL2
Data DL1
Data DL2
Data DL1
Data DL1Data DL2 Data DL
UE
CoreNetwork
Different Types of Handover
8/12/2019 UMTS Basic Principle
43/44
Different Types of HandoverSoft Handover Softer Handover Hard Handover
SRNC DRNC
Node B
UE
Core Network
SRNC
Node B
UE
Core NetworkSRNC
UE
Core Network
GSM / GPRSBSS
SRNC
UE
Core Network
GSM / GPRS
BSS
Inter RNC Intra Node B
W-CDMA Questions
8/12/2019 UMTS Basic Principle
44/44
W-CDMA Questions
1. What is the link between bit rate, chip rate and SF?
2. What is the use of: the downlink & uplink channelization codes?
the downlink & uplink scrambling codes?
3. What is the relationship between Eb/No, Ec/No and the processing gain?
4. What are the different types of Power Control ?
5. The higher the user data rate:
the smaller is the cell?
the wider is the cell?
6. The more loaded the cell:
the smaller the cell?
the wider the cell?
7. Why is macro-diversity an important concept in UMTS?