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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 MobileComm Technologies India Pvt. Ltd.
All rights reserved
MobileComm is committed to providing our customers with quality instructor led
Telecommunications Training.
This documentation is protected by copyright. No part of the contents of this
documentation may be reproduced in any form, or by any means, without the prior written consent of
MobileComm Technologies .
Document Number: RK/CT/3/2010
This manual prepared by: MobileComm Technologies
MobileComm Technologies(India)Pvt. Ltd.
424, First Floor, Udyog Vihar Phase -4,
Gurgaon-122002
Headquarter:
MobileComm Professionals Inc.
1255 West 15th Street, Suite 440
Plano, TX, 75075
Tel: (972) 633-5100
Fax: (972) 633-5106
www.mcpsinc.com
http://www.mcpsinc.com/http://www.mcpsinc.com/ -
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FIGURE OF MERITS IN WCDMA
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WCDMA base station is responsible of
Common channel generation (Pilot, BCCH etc.)
Physical layer processing
RF reception
RF transmission
Signal reception, de-spreading (Rake-receiver)
Signal generation (spreading), channel multiplexing Error correction coding/de-coding
Data detection
Fast closed loop power control
Iub transmission Air interface load measurement, reporting to RNC
Base station tasks
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Base station (RF) configuration options
The main options for the base station configuration are
Number of sectors/cells
Number of carriers per sector
Number of Linear Power Amplifiers
E.g. multiple carriers per Linear Power Amplifiers
Linear Power Amplifier transmit power
Base band signal processing capacity
Required signal processing capacity depends on maximumnumber of connections and connection type (bit rate)
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Base station performance
Base station performance is related to its capability to transmit andreceive radio signals
Transmit capability Total transmit power
Transmit losses
Reception capability
Minimum required signal level = Sensitivity
RF performance
Baseband/algorithm performance
HW Capacity
Signal processing capacity
Transmission capacity
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WCDMA base station transmit power
In WCDMA base stations the transmit power is shared in cell levelbetween
All transmitted physical channels (Common channels, Users) Carriers, if multiple carriers are used
Sectors
WCDMA signal requires linear power amplifier (PA)
Linear modulation (QAM/16-QAM)
Transmitted signal sum of multiple signals
High peak to average ratio
Typical maximum PA output power levels are between 10 and 50 W
In base station configuration large part of output power can be lost toexternal antenna line losses (e.g. 2 6 dB) To be minimised
Physical channel (user) specific maximum power is limited by
Total base station transmit power and amount of DL traffic (DLload)
Channel specific power limitations defined by the system (In NSNRNC/AC)
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WCDMA base station transmit power HSDPA
Available DL power can be allocated to HSDPA transmission
Depends on DL load conditions
Maximum HSDPA power can be limited by RNC parameters
Base station transmit power can be fully utilised HSDPA
No power control headroom required for HSDPA
Same power for all users
Maximise DL capacity
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WCDMA base station sensitivity
Base station sensitivity depends on base station reception RF and baseband performance
Base station reception RF performance is measured by receiver chainnoise figure (NF)
Base station NFis typically measured at the base station input NFdescribes how much the signal quality (C/I) is degraded in the
receiver chain NFis affected by all noise figures, gains and losses in the receiver
chain
Base station reception base band performance in measured byrequired signal quality (Eb/N0) for a given connection quality (BER,BLER)
Theoretical limit defined by channel conditions and signalconfiguration (e.g. channel coding)
Improvement can be achieved by efficient algorithms, e.g. Rakereceiver performance, and implementation
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WCDMA base station sensitivity
The required received signal power can be calculated when theexternal noise and interference power IEXT is known
NFIPGN
E
II
C
P EXTb
TOTRX
1
0
min
)(0
mindBNFIPGIP
EXTN
E
TOTIC
RXb
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Base station reception performance Eb/N0
In order to meet the defined quality requirements (BLER) a certainaverage bit-energy divided by total noise+interference spectral density
(Eb/N0) is needed Eb/N0 is defined at bit detection in the receiver baseband
Eb/N0depends on
Service and bearer
Bit rate, BER requirement, channel coding
Radio channel Doppler spread (Mobile speed, frequency)
Multipath, delay spread
Receiver/connection configuration
Handover situation
Diversity configuration Fast power control usage
Typically given Eb/N0 includes also overhead due to physical layercontrol signalling
Higher bit rates Less overhead Lower Eb/N0
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Required Eb/N0
PGI
C
R
W
I
C
N
Eb
0
NothownDLPIII )1(
NothownULPIII
Where:C = received power
R = bit rate (typically service bit rate)W = bandwidthPG = processing gainIown = total power received from the serving cell (excluding ownsignal)Ioth = total power received from other cellsPN = noise power = orthogonality factor
Energy
per bit
Total powerspectraldensity
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Required Ec /I0
Required Ec/I0 is the required RF C/I needed in order to meet the basebandEb/N0criteria
Ec/N0used often instead ofEc/I0 in same context NOTE: Pilot Ec/N0different measure
Ec/I0depends on the bit rate and Eb/N0
I
C
W
R
N
E
I
Ebc
00
Energyperchip
Total powerspectraldensity
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Base station performance in different frequency bands
The specification requirements for base station sensitivity
and transmit power is same in all frequency bands
OperatingBand
UL FrequenciesUE transmit, Node B receive
DL frequenciesUE receive, Node B transmit
I 1920 1980 MHz 2110 2170 MHz
II 1850 1910 MHz 1930 1990 MHz
III 1710-1785 MHz 1805-1880 MHz
IV 1710-1755 MHz 2110-2155 MHz
V 824 849 MHz 869-894 MHz
VI 830-840 MHz 875-885 MHz
VII 2500-2570 MHz 2620-2690 MHz
VIII 880 915 MHz 925 960 MHz
IX 1749.9-1784.9 MHz 1844.9-1879.9 MHz
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In reality we will have some changes on our overallperformance via frequency change:
Node B noise figure (e.g. Flexi ~2 GHz 2 dB,~900 MHz 2.3 dB),
Node B antenna gain, same size (e.g. ~2 GHz=17.5 dBi, ~900MHz = 14.5 dBi),
Cable loss (e.g. ~2 GHz = 5.9 dB/100 m, ~900MHz= 3.7 dB/100 m),
User equipment noise figure, specification(e.g.~2 GHz 8 dB, ~900 MHz 11 dB)
Propagation, lower frequency has betterpropagation performance. Thus carrierfrequency is affecting a lot on cell rangecalculations.