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MobileComm Technologies India Pvt. Ltd.
Dallas . Atlanta . Washington . LA . Sao Paulo . New Delhi . Toronto. Muscat.Sydney
INTRODUCTION TO TELECOMMUNICATION
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Copyright 2010 MobileCommTechnologies India Pvt. Ltd.
All rights reservedMobileCommis committed to providing our customers with quality instructor ledTelecommunications Training.This documentation is protected by copyright. No part of the contents of thisdocumentation may be reproduced in any form, or by any means, without the prior written consent ofMobileCommTechnologies .Document Number: RK/CT/3/2010
This manual prepared by: MobileCommTechnologies
MobileComm Technologies(India)Pvt. Ltd.424, First Floor, Udyog Vihar Phase -4,Gurgaon-122002Headquarter:MobileComm Professionals Inc.1255 West 15th Street, Suite 440Plano, TX, 75075Tel: (972) 633-5100Fax: (972) 633-5106
www.mcpsinc.com
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MODULE CONTENTS
Standardisation and frequency bands
Multiple access schemes
Main properties of UMTS air interface
HSDPA and HSUPA
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ITU (Global guidelines and recommendations)
IMT-2000: Global standard for third generation (3G) wireless
communications
3GPP is a co-operation between standardisation bodiesETSI (Europe), ARIB/TTC (Japan), CCSA (China), ATIS (North America) and TTA(South Korea)
GSM
EDGE UMTS
WCDMA - FDD
WCDMA - TDD
TD-SCDMA
3GPP2 is a co-operation between standardisation bodiesARIB/TTC (Japan), CCSA (China), TIA (North America) and TTA (South Korea)
CDMA2000
CDMA2000 1x
CDMA2000 1xEV-DO
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Standardisation of 3G cellular networks
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UMTS FDD Frequency band evolution
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THE PROBLEM
LIMITED RESOURCES (FREQUENCY) MANY USERS
So many users, limitedresource ?
SolutionMultiple Access
The Problem
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Channel 1Channel 2Channel 3
Frequency
Time
FDMAfrequency divisionmultiple access
Chan-nel 1
Chan-nel 2
Chan-nel 3
Frequency
Time
TDMAtime divisionmultiple access
Frequency
Time
Code
CDMAcode divisionmultiple access
WCDMA3.84 MHz
Multiple Access Technologies
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What is the multiple access
Technique in UMTS?
WCDMA
Lets understand WCDMA
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5 - Code Multiplexing
Powerspectrum
User 1
User 2
User 3
User 4User 5
Spreading
Code 1
Code 2
Code 3
Code 4
Code 5
Composite signal
5 MHz
Codes discriminate users
Term Wideband and Code Explained
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Spreading codes (channelization codes) used to differentiate mobiles and services different lengths (spreading factor) according to service in UMTS Orthogonal Variable Spreading Factor (OVSF) in UMTS Low Cross Correlation, High Auto Correlation
Scrambling codes used to differentiate un-synchronized codes (from other UEs or Node-Bs) 1 scrambling code per sector on downlink PN code family in UMTS
CODES IN WCDMA
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Scrambling code
Channelization code 1
Channelization code 2
Channelization code 3
User 1 signal
User 2 signal
User 3 signal
BTS
1 - Downlink Transmission on a Cell Level
Codes Multiplexing
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BTS
Channelization code
2 - Uplink Transmission on a Cell Level
Scrambling code 2
User 2 signal
Scrambling code 3
User 3 signal
Channelization code
Channelization code
Scrambling code 1
User 1 signal
Codes Multiplexing
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C0(0)=[1]
C2(1)=[1-1]
C2(0)=[11]
C4(0)=[1111]
C4(1)=[11-1-1]
C4(2)=[1-11-1]
C4(3)=[1-1-11]
C8(0)=[11111111]
C8(1)=[1111-1-1-1-1]
C8(2)=[11-1-111-1-
1]
C8(3)=[11-1-1-1-111]
C8(0)=[1-11-11-11-1]
C8(5)=[1-11-1-11-11]
C8(6)=[1-1-111-1-11]
C8(7)=[1-1-11-111-1]
C16(0)=[............]C16(1)=[............]
C16(15)=[.....
......]
C16(14)=[...........]
C16(13=[...........]
C16(12)=[...........]
C16(11)=[...........]
C16(10)=[.......
....]
C16(9)=[............]
C16(8)=[............]
C16(7)=[............]
C16(6)=[............]
C16(5)=[............]
C16(4)=[............]
C16(3)=[............]
C16(2)=[............]
SF=
1
SF=
2
SF=
4
SF=
8
SF=1
6
SF=25
6
SF=51
2
...
Channelisation Code Tree
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15/4215Frequency (Hz)
Voice user (R=12,2 kbit/s)
Packet data user (R=384 kbit/s)
Po
werdensity(W/Hz)
R
Frequency (Hz)
Gp=W/R=24.98dB
Powerdensity(W/H
z)
R
Gp=W/R=10dB
Spreading sequenceshave a different length Processing gaindepends on the userdata rate
Processing Gain Examples
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The more processing gain the system has, themore the power of uncorrelated interfering signalsis suppressedin the despreadingprocess
Thus, processing gain can be seen as animprovement factor in the SIR (Signal toInterference Ratio) of the signal after despreading
Example: Voice AMR 12.2 Kbps Gp=10*log(3840000/12200)= 25 dB
After despreadingthe signal power has to betypically few dB above the interference and noise:Eb/No = 5dB; therefore the required widebandsignal-to-interference ratiois 5dBGp= -20 dB.
In other words, the signal power can be 20 dBunderunderthe interference and the WCDMAreceiver can still detect the signal
Processing gain
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C Li i
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SF =128
Speech 8 kbps Data 64 kbps Data 384 kbps
BTS
SF =
32SF =4
The coverage limits are determined bythe Uplink link Budget
Coverage Limits
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FREQUENCY PLANNING IN UMTS
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GSM900/1800: 3G (WCDMA):
W CDMA P i i l
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Fast Power Control
Soft Handover
W-CDMA Principles
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F B i
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COVERAGE
CAPACITY QUALITY
POWER
Few Basics.
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U d t di P C t l
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LOWER PowerPer User HIGHER Numberof Users
HIGHER PowerPer User LOWER Numberof Users
Understanding Power Control
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I t f
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No orImproper Power Control leads to High interference that impacts Coverage,Capacity and Quality
Power Ctrl
ON
OFF
Interference
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Power Control
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TX Power is adjusted regularly so that each connection is received with the required
Eb/No of its service Uplink: Avoid Near-Far-Problem
Downlink: Power share allocation
Policy: No one gets a higher quality (Eb/No) than he needs. Everyone gets exactlythe required quality or is not served at all
no unnecessary increase of interference for other mobiles no waste of common power resource in the downlink
Power Control
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Interference Limit
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When the number of users in the cellincreases, the interference levelincreases (noise rise), the required
received power at the base station toreach a given Eb/No (quality)increases
For high interference level, therequired received power becomesinfinite: power control is unstable pole capacity
Coverage and capacity are linked inCDMA systems
For high interference level, therequired received power becomesinfinite: power control is unstable pole capacity
Coverage and capacity are linked in
CDMA systems
0
2
4
6
8
1012
14
16
18
20
0 10 20 30 40 50 60 70
Number of simultaneous users per sector
Interferencelevelrelativ
etoNoiselevel
(dB)
Interference Limit
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Downlink Power Limit : Cell breathing
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Considering the limitation of maximal transmit power, the increase of
required received power due to high traffic will lead to decrease the cellrange
The cell coverage decreases when the traffic increases : so-calledcellbreathingphenomenon
Coverage and capacity are linked in CDMA systems
Downlink Power Limit : Cell breathing
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Taking advantage of Multipath: Rake Receiver
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TX
D(t)
Delay0
Delay1
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 of
multipath diversity
BTS
UE
Spreading &
Scrambling
Taking advantage of Multipath: Rake Receiver
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POWER CONTROL
Power control (PC) in WCDMA
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Fast, accurate power control is of utmost importance particularly in UL;
UEs transmit continuously on same frequency Always interferencebetween users
Poor PC leads to increased interference reduced capacity
Every UE accessing network increases interference
PC target to minimise the interference Minimize transmit power of each
link while still maintaining the link quality (BER)
Mitigates 'near far effect in UL by providing minimum required power for eachconnection
Power control has to be fast enough to follow changes in propagationconditions (fading)
Step up/down 1500 times/second
Power control (PC) in WCDMA
Power Control types
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Power control functionality can be divided to three main types
Open loop power control
Initial power calculation based on DL pilot level/pathloss measurement by UE
Outer (closed) loop power control
Connection quality measurement (BER, BLER) and comparison to QoS target
RF quality target (SIR target) setting for fast closed loop PC based on connection
quality
Fast closed loop power control
Radio link RF quality (SIR) measurement and comparison to RF quality target (SIRtarget)
Power control command transmission based on RF quality evaluation
Change of transmit power according to received power control command
Power Control types
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HANDOVERS
Different Types of Handover
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Soft Handover Softer Handover Hard Handover
SRNC DRNC
Node B
UE
Core Network
SRNC
Node B
UE
Core NetworkSRNC
UE
Core Network
GSM / GPRBSS
SRNC
UE
Core Network
GSM / GPRBSS
Inter RNC Intra Node B
Different Types of Handover
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Soft Handover
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In UL selection of the best signal on a framebasis at RNC level - selection diversity
In DL Maximum Ratio combining due to RAKE
receiver at UE
In UL Maximum. Ratio Combining at Node B
In DL Maximum Ratio combining due to RAKEreceiver at UE
Soft HO
Softer HO
RNC
RNC
Soft Handover
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SERVICES IN UMTS
UMTS QoS class
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UMTS QoS class
NRT Data Call
BackgroundClass
PS Data Call
Interactive Class
PS Data Call
Streaming Class
PS Data Call
Conversational Class
CS Data Call
CS Data Call CS Voice Call
CS Call
RT Data Call
PS Call
Call
HSDPA
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2002.6 R5 released
2003.6 HSDPA (High Speed Downlink Packet Access) was added into R5
HSDPA is smoothly evolved from WCDMA R99 without any big effect to the existing
R99 network
1 new transport channel: HS-DSCH
3 new physical channels HS-PDSCH, HS-SCCH and HS-DPCCH
MAC-hs sub-layer, HARQ (Fast Hybrid Automatic Repeat reQuest), Fast Scheduling
and AMC (Adaptive Modulation and Coding)
HSDPA --Max. downlink data rate: 14.4Mbps
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AMC
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Node B
CQI (Report periodically)
Modulation (QPSK, 16QAM) self-adaptiveGood channel state: 16QAMBad channel state: QPSK
Coding rate (1/3, 3/4, etc.) self-adaptiveGood channel state: 3/4
Bad channel state: 1/3
Efficiently utilize the channel condition
Good channel state: higher speedBad channel state: lower speed
Codes adjustingGood channel state: more codesBad channel state: fewer codes
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HSUPA
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THE END