5.figures of merit

8/22/2019 5.Figures of Merit

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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.

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