001 WCDMA RNP Fundamental

8/22/2019 001 WCDMA RNP Fundamental

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1HUAWEI Mexico Training Center

WCDMA RNP Fundamental

HUAWEI TECHNOLOGIES CO., LTD. All rights reserved

www.huawei.com

Internal

OWJ100001 WCDMARNP Fundamental

ISSUE 1.0


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HUAWEI TECHNOLOGIES CO., LTD. Page 2All rights reserved

Upon completion of this course, you will be able to:

Get familiar with principles of radio wave

propagation, and theoretically prepare for the

subsequent link budget.

Introduce the knowledge about antennas and the

meanings of typical indices.


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ChapterChapter 1 Radio1 Radio WaveWave IntroductionIntroduction

ChapterChapter 22 AntennaAntenna

ChapterChapter 3 RF Basics3 RF Basics

ChapterChapter 44 SymbolSymbol ExplanationExplanation


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Section 1 Basic Principles of Radio WaveSection 1 Basic Principles of Radio Wave

Section 2 Propagation Features of Radio WaveSection 2 Propagation Features of Radio Wave

SectionSection 3 Propagation Model of Radio Wave3 Propagation Model of Radio Wave

SectionSection 4 Correction of Propagation Model4 Correction of Propagation Model


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Radio Wave SpectrumRadio Wave Spectrum

The frequencies in each specific band present unique propagation features.300-3000GHz

EHFExtremely High

Frequency

30-300GHz

SHFSuper High Frequency3-30GHz

UHFUltra High Frequency300-3000MHz

VHFVery High Frequency30-300MHz

HFHigh Frequency3-30MHz

MFMedium Frequency300-3000KHz

LFLow Frequency30-300KHz

VLFVery-low Frequency3-30KHz

VFVoice Frequency300-3000Hz

ELFExtremely Low

Frequency

30-300Hz3-30Hz

DesignationClassificationFrequency

The radio waves are distributed in 3Hz ~ 3000GHz. This spectrum is

divided into 12 bands, as shown in the above table. The frequencies in

each specific band present unique propagation features: The lower the

frequency is, the lower the propagation loss will be, the farther the

coverage distance will be, and the stronger the diffraction capability will

be. However, lower-band frequency resources are stringent and the

system capacity is limited, so they are primarily applied to the systems of

broadcast, television and paging. The higher-band frequency resources

are abundant and the system capacity is large; however, the higher the

frequency is, the higher the propagation loss will be, the shorter the

coverage distance will be, and the weaker the diffraction capability will be.

In addition, the higher the frequency is, the higher the technical difficulty

will be, and the higher the system cost will be. The band for purpose of

the mobile communication system should allow for both coverage effect

and capacity. Compared with other bands, the UHF band achieves agood tradeoff between the coverage effect and the capacity, and is hence

widely applied to the mobile communication field. Nevertheless, with the

increase of mobile communication demand, more capacity is required.

The mobile communication system is bound to develop toward the high-

frequency band.


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Propagation of Electromagnetic Wave

When the radio wave propagates in the air, the electric f ield direction

changes regularly. If the electric field direction of radio wave is vertical to theground, the radio wave is vertical polarization wave.

If the electric field direction of radio wave is parallel with the ground, the

radio wave is horizontal polarization wave

electric wave transmission direction

Electric FieldElectric Field

Magnetic FieldMagnetic Field

Electric Field

Dipole

Propagation of electromagnetic propagation takes on an energy

propagation mode. During the propagation, the electric field is vertical to

the magnetic field, both vertical to the propagation direction. Through

interaction between the electric field and the magnetic field, the energy is

propagated to the distance, just like propagation of water waves.


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Perpendicular incidence waveand ground refraction wave

(most common propagation modes)

Troposphere reflection wave

(the propagation is very random)

Mountain diffraction wave

(shadow area signal source)

Ionosphere refraction wave(beyond-the-horizon communication path)

Propagation Path

Radio wave can be propagated from the transmitting antenna to the

receiving antenna in many ways: perpendicular incidence wave or ground

refraction wave, diffraction wave, troposphere reflection wave, ionosphere

reflection wave, as shown in the diagram. As for radio wave, the most

simple propagation mode between the transmitter and the receiver is freespace propagation. One is perpendicular incidence wave; the other is

ground reflection wave. The result of overlaying the perpendicular

incidence wave and the reflection wave may strengthen the signal, or

weaken the signal, which is known as multi-path effect. Diffraction wave is

the main radio wave signal source for shadow areas such building interior.

The strength of the diffraction wave is much dependent of the propagation

environment. The higher the frequency is, the weaker the diffraction

signal will be. The troposphere reflection wave derives from the

troposphere. The heterogeneous media in the troposphere changes fromtime to time for weather reasons. Its reflectance decreases with the

increase of height. This slowly changing reflectance causes the radio

wave to curve. The troposphere mode is applicable to the wireless

communication where the wavelength is less than 10m (i.e., frequency is

greater than 30MHz).Ionosphere reflection propagation: When the

wavelength of the radio wave is less than 1m (frequency is greater than

300MHz), the ionosphere is the reflector. There may be one or multiple

hops in the radio wave reflected from the ionosphere, so this propagation

is applicable to long-distance communication. Like the troposphere, the


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Building reflection waveBuilding reflection wave

Diffraction waveDiffraction wave

Direct waveDirect wave

Ground reflection waveGround reflection wave

Propagation Path

In a typical cellular mobile communication environment, a mobile station

is always far shorter than a BTS. The direct path between the transmitter

and the receiver is blocked by buildings or other objects. Therefore, the

communication between the cellular BTS and the mobile station is

performed via many other paths than the direct path. In the UHF band,the electromagnetic wave from the transmitter to the receiver is primarily

propagated by means of scattering, namely, the electromagnetic wave is

reflected from the building plane or refracted from the man-made or

natural objects.


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Section 2 Propagation Features of Radio WaveSection 2 Propagation Features of Radio Wave

SectionSection 3 Propagation Model of Radio Wave3 Propagation Model of Radio Wave



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Radio Propagation Environment

Radio wave propagation is affected by topographic structure and

man-made environment. The radio propagation environment directly

decides the selection of propagation models. Main factors that affect

environment are:

Natural landform (mountain, hill, plains, water area)

Quantity, layout and material features of man-made buildings

Natural and man-made electromagnetic noise conditions

Weather conditions

Vegetation features of the region

The radio wave is largely affected by the topography and man-made

environment. The natural landforms such as mountains and hills as well

as man-made buildings affect the propagation features of radio waves.

Weather and time conditions also affect propagation of radio wave. For

example, the ionosphere is relatively stable at night, so the shortwaveradio is well received.


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Quasi-smooth landformThe landform with a slightly rugged surface and

the surface height difference is less than 20m

Irregular landform

The landforms apart from quasi-smooth landform

are divided to: hill landform, isolated hills, slant

landform, and land & water combined landform.

R

T

T

R

Landform Categories

The quasi-smooth landform refers to the landform with a slightly rugged

surface, and the surface height difference is less than 20m. The average

surface height difference is slight. The Okumura propagation model

defines the roughness height as the difference between 10% and 90% of

the landform roughness in 10km in front of the mobile station antenna.CCIR defines it as the difference between the height over 90% and the

height over 10% of landform height at 10~50 km in front of the receiver.

Other landforms than abovementioned are called irregular landforms.


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distance (m)

Receiving power (dBm)

10 20 30

-20

-40

-60

slow fading

fast fading

Signal Fading

Slow fading: In case shadow effect is caused by obstacles, and thereceiving signal strength decreases but the field strength mid-valuechanges slowly with the change of the topography, the strength decreaseis called slow fading or shadow fading. The field strength mid-value ofslow fading takes on a logarithmic normal distribution, and is related to

location/locale. The fading speed is dependent on the speed of the mobilestation.

Fast fading: In case the amplitude and phase of the combined wavechange sharply with the motion of the mobile station, the change is calledfast fading. The spatial distribution of deep fading points is similar tointerval of half of wavelength. Since its field strength takes on Rayleighdistribution, the fading is also called Rayleigh fading. The amplitude,phase and angle of the fading are random.

Fast fading is subdivided into the following three categories:

Time-selective fading: In case the user moves quickly and causesDoppler effect on the frequency domain, and thus results in frequencydiffusion, time-selective fading will occur.

Space-selective fading: The fading features vary between different placesand different transmission paths.

Frequency-selective fading: The fading features vary between differentfrequencies, which results in delay diffusion and frequency-selectivefading.


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In order to mitigate the influence of fast fading on wireless communication,

typical methods are: space diversity, frequency diversity, and time diversity.


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Signal Diversity

Measures against fast fading --- Diversity

Time diversity

Space diversity

Frequency diversity

To resist such kind of fast fading, the BTS adopts the time diversify, space

diversity (polarization diversity), and frequency diversity.

Time diversity uses the methods of symbol interleaving, error check and error

correction code. Each code has different anti-fading features.

Space diversity uses the main/diversity antenna receiving. The BTS receiverhandles the signals received by the main and diversity antennas respectively,

typically in a maximum likelihood method. This main/diversity receiving effect is

guaranteed by the irrelevance of main antenna receiving and diversity antenna

receiving. Here irrelevance means the signals received by the main antenna

and the signals received by the diversity antenna do not have the feature of

simultaneous attenuation. This requires the interval between the main antenna

and the diversity antenna in case of space diversity to be greater than 10 times

of the radio signal wavelength (for GSM, the antenna interval should be greater

than 4m in a distance of 900m, and greater than 2m in a distance of 1800m).

Alternatively, the polarization diversity method should be used to ensure that

signals received by the main and diversity antennas do not have the same

attenuation features. As for mobile stations (mobile phones), only one antenna

exists, so this space diversity function is not supported. The BTS receivers

capability of balancing the signals of different delays in a certain time range

(time window) is also a mode of space diversity. In case of soft switch in the

CDMA communication, the mobile station contacts multiple BTSs concurrently,


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and selects the best signals from them, which is also a mode of space

diversity.

Frequency diversity is performed primarily by means of spreading. In the

GSM communication, it simply uses the frequency hopping to obtain the

frequency hop gain; in the CDMA communication, since every channelworks at a broad band (WCDMA has a band of 5MHz), the communication

itself is a kind of spreading communication.


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SolutionRAKE technologyRAKE technology

Radio Wave Delay Extension

Deriving from reflection, it refers to the co-frequency interference caused

by the time difference in the space transmission of main signals and

other multi-path signals received by the receiver.

The transmitting signals come from the objects far away from the

receiving antenna.

Radio wave delay extensionAnother type of frequency-selective fading.

The spatial distribution of deep fading points is similar to interval of half of

a wavelength (17cm for 900MHz, 8cm for 1800/1900MHz). If the mobile

station antenna is located at this deep fading point at this time (when the

mobile user in a car resides in this deep fading point in case of a red light,we call it read light problem), the voice quality is very poor, and relevant

technologies should be used to resolve it, e.g., the Rake technology in

CDMA system.


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T

R

Diffraction Loss

The electromagnetic wave diffuses aroundat the diffraction point.

The diffraction wave covers all directions

except the obstacle.

The diffusion loss is most severe

When analyzing the transmission loss in the mountains or the built-up

downtowns, we usually need to analyze the diffraction loss and

penetration loss. Diffraction loss is a measure for the obstacle height and

the antenna height. The obstacle height must be compared with the

propagation wavelength. The diffraction loss generated by the height ofthe same obstacle for the long wavelength is less than that for short

wavelength. Diffraction loss is caused the electromagnetic wave being

scattered around at the diffraction point, and the diffraction wave covers

all directions except the obstacle. This diffusion loss is most severe, and

the calculation formula is complicated and varies with different diffraction

constants.


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Penetration Loss

Penetration loss caused by obstructions:

XdBmWdBm

Penetration loss =X-W=B dBPenetration loss =X-W=B dB

Indoor penetration loss refers to the difference between the average

signal strength outside the building and the average signal strength of one

layer of the building.

Penetration loss represents the capability of the signal penetrating the

building. The buildings of different structures affect the signals

significantly. The penetration loss generated by the long wavelength is

greater than that generated by the short wavelength of the same building.

The incidence angle of the electromagnetic wave also affects the

penetration loss considerably.

Typical Penetration loss:

Wall obstruction : 5~20dB

Floor obstruction : >20dB

Indoor loss value is the function of the floor number : -1.9dB/floor

Obstruction of furniture and other obstacles: 2~15dB

Thick glass : 6~10dB

Penetration loss of train carriage is 15~30dB

Penetration loss of lift is : 30dB

Dense tree leaves loss : 10dB


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SectionSection 2 Propagation Features of Radio Wave2 Propagation Features of Radio Wave

Section 3 Propagation Model of Radio WaveSection 3 Propagation Model of Radio Wave


Propagation model is very important. It is the foundation of the mobile

communication planning. The propagation model of radio wave is a

process of using the actual measurement and computers to develop

curves from the measured results in different regions and ultimately

outline the propagation formula of the radio wave in different topographicconditions. For example, the Okumura model introduced below is an

empiric formula obtained by the Japanese Okumura from measurement of

tens of thousands of curves in Tokyo. It is now widely recognized and

accepted, plays important roles in guiding the construction of

communication networks. This session deals with the typical propagation

models currently available.


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Propagation model is used for predicting the medium value of path loss. The formula

can be simplified under if the heights of UE and base station are given

where: is the distance between UE and base station, and is the frequency

Propagation environment affect the model, and the main factors are :

Natural terrain, such as mountain, hill, plain, water land, etc;

Man-made building (height, distribution and material);

Vegetation;

Weather;

External noise

),( fdfPathLoss =

d f

Propagation model

If the heights of UE and BTS are given and ignore the environment affect,

the path loss is just related with the distance between UE and BTS and

radio frequency.


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Lo=91.48+20lgd, for f=900MHz

Lo=97.98+20lgd, for f=1900MHz

Free Air Space Model

Free space propagation model is applicable to the wireless

environment with isotropic propagation media (e.g., vacuum),

and is a theoretic model.

This environment does not exist in real life

Free space means an infinite space full of even, linear, isotropic ideal

media, and is an ideal situation. For example, the radio wave propagation

of satellite is very similar to the propagation condition of free space. As

seen from the above formula, once the distance is doubled, the loss will

increase by 6dB. If the frequency is doubled, as shown in the aboveexample, the 1900MHz loss will be 6dB more than the 900MHz loss.


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Ploss = L0+10lgd -20lghb - 20lghm

Path loss gradient , usually is 4

hb BTS antenna height

hm mobile station height

L0 parameters related to frequencyR

T

Flat Landform Propagation Model

In the flat landform propagation model, in addition to the frequency and

distance, we also consider the heights of the UE and BTS. Once the BTS

antenna height is doubled, the path loss will be compensated for by 6dB.


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Application ScopeApplication Scope

CharacteristicCharacteristic

Frequency range f:150~1500MHz

BTS antenna height Hb:30~200m

Mobile station height Hm:1~10m

Distance d:1~20km

Macro cell model

The BTS antenna is taller than the surrounding buildings

Predication is not applicable in 1km

Not applicable to the circumstance where the frequency is above

1500MHz

Okumura-Hata Model

The Okumura-Hata model is commonly used in the planning software. It

is applicable to the micro cell that covers more than 1km below 1500MHz.

In 1960s, Okumura and his men used a broad range of frequencies,

heights of several fixed stations and heights of several mobile stations to

measure the signal strength in all kinds of irregular landforms andenvironments, and developed a series of curves, then set up a model by

fitting the curves to obtain the empiric formula of propagation model. This

model has been widely used across the globe, and is applicable to areas

outside Tokyo by use of the correction factor.


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Frequency range f:1505~2000MHz

BTS antenna height Hb:30~200m

Mobile station height Hm:1~10m

Distance d:1~20km


Macro cell model

The BTS antenna is taller than the surrounding buildings

Predication is not applicable in 1km

Not applicable to the circumstance where the frequency is above2000MHz or below 1500MHz

COST 231-Hata Model

The COST231 model is applicable 1500-2000MHz, and is not accurate

within 1km. The COST231-hata model is based on the test results of

Okumura, and works out the suggested formula by analyzing the

propagation curve of higher bands.


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Frequency range : 800~2000MHz

BTS antenna height Hbase : 4~50m

Mobile station height Hmobile : 1~3m

Distance d : 0.02~5km


Urban environment, macro cell or micro cell

Not applicable to suburban or rural environment

COST 231 Walfish-Ikegami Model

The COST231 propagation model team of the European Research

Committee puts forward the following two suggested models: One is

based on the Hata model, and works out the frequency coverage extends

from 1500MHz to 2000MHz by using some correction items. However, in

all the test environments, the BTS is taller than the surrounding buildings,so it is not appropriate to extend the valid range to the circumstance

where the BTS antenna is lower than the surrounding buildings. This

model is applicable to large-cell macro cell. In the micro cell, the BTS

antenna is lower than the roof, so the Committee created the COST-

Walfish-Ikegami model according to the results of Walfishs calculation of

the urban environment, the Ikegamis corrective function for handling the

street direction and the test data. This model is tested in a German city

Mannheim, and more improvements are found to be made. When using

the model, some parameters that describe the urban environmentfeatures may be required: Building height Hroof (m) Pavement width w (m)

Building interval b (m) Street direction against the perpendicular incidence

wave direction ( )


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K1

Propagation path loss constant value

K2 log(d) correction factor D

Distatnce between receiver and transmitter (m);K3

log(HTxeff) correction factor;

HTxeff Transmitter antenna height (m);

K4 Diffraction loss correction factor;K5

log(HTxeff)log(D) correction factor;

K6

Correction factor; Receiver antenna height (m);

Kclutter: clutter correction factor;

( )

( ) ( ) ( ) ( )clutterfKHKHDKlossnDiffractioKHKDKKPathLoss

clutterRxeffTxeff

Txeff

+++

+++=

65

4321

loglog

loglog

RxeffHRxeff

H

Experimental formulaExperimental formula

ExplanationExplanation

Standard Propagation

Using the multiplier factor configured by customer, the propagation model

can be made by order totally. It can support using different K1 and K2

according to distance and LOS or NLOS. It also can use different

diffraction loss algorithm and effective BTS height algorithm. One optional

amendment condition is that U-net can amend the path loss of hillyterrains environments under it is LOS between transmitter and receiver.


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SectionSection 1 Basic Principles of Radio Wave1 Basic Principles of Radio Wave

SectionSection 2 Propagation Features of Radio Wave2 Propagation Features of Radio Wave

SectionSection 3 Propagation model of Radio Wave3 Propagation model of Radio Wave

Section 4 Correction of Propagation ModelSection 4 Correction of Propagation Model

Propagation model of radio wave have close relation with concrete terrain

and clutter. Usually, classical theoretical analysis of propagation model

have biggish error. So, in practice, we use test statistics method, namely,

using a great deal test data to amend the classical model. Here we use

the CW test.


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Basic Principles and Procedures

Error compliant with

requirements?

Target propagation environment

CW data collection

Measured propagation path loss

Selected propagated environment

parameter setting

Forecast propagation path loss

Comparison

End

Due to difference of propagation environment, the propagation model

parameters must be corrected based on measured values, so as to

embody the radio wave propagation features of the actual environment.

Generally, we use the Continuous Wave (CW) test method to measure

the propagation path loss in the actual environment. By comparing theactual value with the forecast value, we adjust the parameters in the

model. The process recurs until the error meets the requirements.


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5m

Criteria for selecting a site:

The antenna height is greater than 20m.

The antenna is at least 5m taller than the nearest obstacle

Site Selection

If the antenna is taller than the nearest obstacle by 5m or more, the data

in GSM will be inherited, as defined according to the first Fresnel zone.

This condition is sufficiently compliant with the WCDMA requirements.

Obstacle here means the tallest building on the roof of the antenna. The

building serving as a site should be taller than the average height of the

surrounding buildings


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Transmitting subsystems

transmitting antenna, feeder, high-frequency signal source, antenna bracket

Omni-Antenna

Transmitter

Antenna

bracket

Feeder

Test Platform

After the test platform is set up, switch on the signal source to transmit

the RF signal, and begin drive test. To perform the CW test, it is

necessary to select an appropriate site for transmitting the RF signal. In

case of CW test data handling, it is necessary to be aware of the EIRP of

the test BTS, and record the data of signal gain attributable to each part,including signal source transmitting power, RF cable loss, transmitting

antenna gain, and receiving antenna gain.


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Receiving subsystem

Test receiver, GPS receiver, test software, portable

PositioningSystem

Data Acquisition System

GPS-Antenna Antenna

Receiver

Test Platform

After the test platform is set up, switch on the signal source to transmit

the RF signal, and begin drive test. To perform the CW test, it is

necessary to select an appropriate site for transmitting the RF signal.In

case of CW test data handling, it is necessary to be aware of the EIRP of

the test BTS, and record the data of signal gain attributable to each part,including signal source transmitting power, RF cable loss, transmitting

antenna gain, and receiving antenna gain.


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Rules of selecting a test path:

Landform: the test path must consider all main landforms in the region.

Height: If the landform is very rugged, the test path must consider the

landforms of different heights in the region.

Distance: The test path must consider the positions differently away

from the site in the region.

Direction: The test points on the lengthways path must be identical with

that on the widthways path.

Length: The total length of the distance in one CW test should be

greater than 60km.

Number of test points: The more the test points are, the better (>10000

points, >4 hours as a minimum)

Test Path

The distance corrected in the CW test primarily falls within the impact

range of this cell, so the test distance is not necessarily more than twice

of the cell radius. The total length of the test distance in a CW test should

be greater than 60km.Generally, the number of test points for each site is

more than 10000, or the test duration is more than 4 hours. According tothe sampling rate of 1 point/6m after smoothing the sampling data, it

takes at least 60km as a test distance for 10000 sampling points.


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Rules of selecting a test path:

Test Path

Overlaying: The test path of different test sites can be preferably

overlapped to increase the reliability of the model

Obstacles: When the antenna signals are obstructed by one side of the

building, do not run to the shadow area behind this side of building


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The sampling law is meets the Richard Law :40 wavelengths, 50

sampling points

Upper limit of drive speed: Vmax=0.8/Tsample

The test results obtained in exceptional circumstances must be

removed from the sampling data.

Sampling point with too high fading (more than 30dB) ;

In a tunnel

Under a viaduct

If using a directional antenna for CW test, the test path is selected

from the main lobe coverage area.

Drive Test

Sampling distance: The distance between adjacent sampling points

should be -/4 so as to eliminate the impact of Raylaigh fading.

Suppose the sampling frequency of the drive test equipment is:

1000HzThe 2G band bearer wavelength is: 0.15m (50 sampling points

are required per 6m)Upper limit of drive speed: 0.8*0.15*1000=120m/s


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The test data needs to be processed before being

able to be identified by the planning software. The

processing procedure is :

Data filtering

Data dispersion

Geographic averaging

Format conversion

Test Data Processing

The CW test data obtained after reasonable design are basis of our model correction,

and are input of the first step. The reasonableness of the CW test data directly affects the

correctness of the correction result. However, even the design is reasonable, the

measured data is not perfect, and needs further processing. Typical processing steps

include: Data filtering, data dispersion, geographical averaging, and format conversion. In

the actual test, some test data may be inconsistent with the model correction

requirements. In order to avoid such data from affecting the model correction result

adversely, such data should be filtered. 1. Since we need to know the accurate position

of each test point in the model correction, for the data obtained from measuring the

places where GPS cannot position accurately should be filtered. Such circumstances

include: 1) under a viaduct; 2) in a tunnel; 3) in the narrow street with tall buildings on

both sides; 4) in the narrow street covered by dense tree leaves. 2. Generally, we regard

the distance 0.1R~2R away from the antenna is reasonable, where R is the forecast cell

radius. The signal strength distribution and the propagation distance do not form a strict

linear relationship. If too near, the test data will be less, and average distribution will be

impossible. 3. If the receiving signal is too weak, exceptional value point may occur,

because the receiver is located at the critical status of resolving the signal at this time,

and its value is vulnerable to influence of transient fluctuation. To prevent the deeplyfaded signals from being filtered, we use the homocentric circle technology to filter out

circular rings at the test point lower than-121dbm, e.g., above 20% of the site ring. That

is because the


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receiver speed is far greater than the GPS signal collection speed, andwill result in multiple test data at one location point. Suppose the vehicleruns at equal speeds, such data should be distributed to the two fixedpoints on average, which is a process of data dispersion. The mainfunction of geographic averaging is to eliminate the influence of fastfading and slow fading.


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Questions

Which band of radio wave is used for the mobile communication system?

What are the two modes of signal fading in the radio propagation

environment? What are their characteristics and reasons of generation?


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Summary

This chapter deals with radio wave. The learning points

include:

Propagation path of radio wave

Loss and dispersion characteristics of radio wave,

and main compensation solutions

Typical radio wave models, main parameters

involved

Methods of correcting radio propagation models


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Positions and Functions of Antenna

Lightning protectiondevice

main feeder(7/8)

Feederclip

Cablingrack

Grounding device

3-connector seal componentinsulation sealing tape, PVC

insulation tape

Antenna adjustment bracket

GSM/CDMAplate-shape

antenna

radio mast (50~114mm)

Outdoorfeeder

Indoor superflexible feeder

Feeder cablingwindow

main deviceof BTS

BTS antenna & feeder system diagramBTS antenna & feeder system diagram

Positions and functions of antenna: In the radio communication system,

antenna is an interface between the transceiver and the outside

communication media. An antenna may both emit and receive radio

waves; it converts the high-frequency current to electromagnetic wave

when transmitting; and converts the electromagnetic wave to high-frequency current when receiving. Other parts of the antenna & feeder are

shown in the diagram.


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omni antenna

Antenna

Connector

Dipole

Feed network

Antenna

Connector

Feed network

Dipole

Directional antenna

Feed network

Working Principles of Mobile Antenna

The BTS antenna in mobile communication system is antenna array

consist of a lot of basic dipole units. The dipole unit is half wave dipole

that the length of dipole is half wave of electromagnetic wave. The feed

network usually use equal power network.

For directional antenna, there is a metal flat at the back of dipole units as

a reflection plane to increase the antenna gain.

The tie-in of antenna usually is DIN type (7/16''). Usually it is at the bottom

of antenna, sometimes at the back of antenna.

Structurally, the dipole units and feed network are covered by antenna

casing to protect the antenna. Usually, the antenna casing is made by

PVC material or tempered glass, and the loss for electromagnetic wave is

less and the strength is better.


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Categorize by emission direction

Directional antenna omni antenna

Categories of Antenna

By emission direction, antennas are categorized into directional antenna

and omni antenna.

Directional antenna usually is used in urban area, and omni antenna is

used in rural area for wide coverage.


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Plate-shape antenna Cap-shape antenna

Whip-shape Paraboloid antenna

Categorize by appearanceCategorize by appearance


The installed antennas can be categorized into plate-shape antenna, cap-

shape antenna, whip-shape, and paraboloid antenna. As shown in the

above diagram, the cap-shape antenna is generally used in indoor

distribution system, while the paraboloid antenna is mainly used for

satellite communication and radar.


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Omni antennaUni-polarization

Directional antennaDual polarization

Directional antenna

Categorize by polarization modeCategorize by polarization mode


By polarization mode, antennas are categorized into: vertical polarization

antenna (or unipolarization antenna), cross polarization antenna (or dual

polarization antenna). The foregoing two polarization modes are both line

polarization mode. Circle polarization and oval antenna are usually not

used in GSM. Unipolarization antennas are mostly vertical polarizationantennas. The polarization direction of their dipole unit is in the vertical

direction. Dual polarization antennas are mostly 45-degree slant

polarization antennas. Their dipole unit is a dipole that crosses the

leftward tilt 45-degree polarization and rightward tilt 45-degree

polarization, as shown in the above diagram. The dual polarization

antennas are equivalent to two unipolarization antennas combined into

one. Use of dual polarization antennas can reduce the number of

antennas on the tower, and reduce the workload of installation, hence

reduces the system cost, so they are popularly applied now.


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Smart antennaSmart antenna

Smart directional antenna Smart omni-antennaSmart directional antenna


Smart antenna techniques are already used in many wireless systems,

but UMTS is the first system where they are considered already in the

system specification phase. Smart antennas are especially attractive in

WCDMA networks, as they could be used to reduce the intracell

interference levels considerably. Interference is one of the most importantand difficult issues in the WCDMA air interface, and any improvement in

the interference level management will bring increased capacity.

Generally, a smart antenna is an antenna structure consisting of more

than one physical antenna element, and a signal processing unit that

controls these elements and combines or distributes the signals among

these elements. Note that the antenna elements are not smart as such,

but the smartness of the device lies in the controlling signal processing

unit.


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Electric down tilt AntennaElectric down tilt Antenna

Electrical down tilt Antenna


The main parts of electric down tilt antenna:

1. RCU (Remote Control Unit)

2. SBT (Smart Bias-Tee)

3. BT (Bias-Tee)

4. STMA (Smart TMA)


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Electric Indices of Antenna

Electric performances include: working band, gain, polarization mode,

lobe width, preset tilt angle, down tilt mode, down tilt angle adjustment

range, front and back suppression ratios, side lobe suppression ratio,

zero point filling, echo loss, power capacity, impedance, third order inter-

modulation.


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Top view side view

directional antenna direction diagramomni antenna direction diagram

Symmetric halfSymmetric half--wave dipolewave dipole

Antenna Direction Diagram

Direction ability of antenna refers to the capability of the antenna emitting

electromagnetic waves toward a certain direction. For a receiving antenna,

the direction ability means the capability of the antenna receiving radio

waves from different directions. The characteristic curve of direction ability

of antenna is generally represented in a direction diagram.

Direction diagram is used for describing the capability of the antenna

receiving/emitting electromagnetic waves in different directions of the air.


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dBi

dBd

2.15dB

Antenna Gain

Gain means a ratio of the power density generated by the antenna at a

certain point in the maximum emission direction to the power density

generated by the ideal point source antenna at the same point. Gain

reflects the capability of the antenna emitting the radio waves in a certain

direction in a centralized way. Generally, the higher of the antenna gain is,the narrower the lobe width will be, and more centralized the energy

emitted by the antenna will be. The unit of antenna gain is dBi or dBd. dBi

uses the ideal point source antenna gain as a reference, and dBd uses

the half-wave dipole antenna gain as a reference. The difference of

values represented by the two kinds of unit is 2.15 dB. For example, if the

antenna gain is 11dBi, it can be said as 8.85dBd, as shown in the above

diagram. dBi is defined as the energy centralization capability of the

actual direction antenna (including omni antenna) relative to the isotropic

antenna, where i represents Isotropic.dBd is defined as the energycentralization capability of the actual direction antenna (including omni

antenna) relative to the half-wave dipole antenna, where d represents

Dipole.


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Antenna Pattern

Antenna pattern

It is a three-dimensional solid pattern. It show the theoretic pattern of one

directional antenna.


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Antenna Pattern

Side lobe

Zero point filling

Main lobe

Max value

Zero point filling

Vertical pattern

Back lobe

horizontal half-power

angles

Horizontal pattern

Front to back

ratio

Beam width is one of the key indices of antenna. It consists of horizontal

half-power angle and vertical half-power angle. Horizontal half-power

angle/vertical half-power angle is defined as beam width between the two

points where the power is reduced by half (3dB) in the horizontal/vertical

directional relative to the maximum emission direction. Typical horizontal

half-power angles of BTS antenna are 360, 210, 120, 90, 65,

60, 45 and 33. Typical vertical half-power angles of BTS antenna

are 6.5, 13, 25 and 78. The front/back suppression ratio means

the ratio of signal emission strength of the antenna in the main lobe

direction and in the side lobe direction, and the difference between the

side lobe level and the maximum beam within backward 18030.

Generally, the front/back ratio of antenna falls within 18~45dB. For dense

urban areas, the antenna with great front/back suppression ratio is

preferred. Zero point filling: When the BTS antenna vertical plane adopts

the shaped-beam design, in order to make the emission level in theservice are more even, the first zero point of the lower side lobe should be

filled, rather than leaving an obvious zero depth. High-gain antennas have

narrow vertical half-power angles, so especially need the zero point filling

technology to improve the nearby coverage. Generally, if the zero depth

is -26dB greater than the main beam, it indicates that the antenna has

zero point filling. Some suppliers adopt percentage notation. For example,

when an antenna zero point filling is 10%. The relationship between the


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two notation methods is:

Y dB=20log(X%/100%)

For example, zero point filling 10%, namely, X=10; using dB to notate it:

Y=20log(10%/100%)=-20dBUpper side lobe suppression: For the cellular

system based on minor cell system, in order to improve the frequency

multiplexing and reduce the co-frequency interference between adjacent

cells, the BTS antenna lobe shaping should lower the side lobe aimed at

the interference area, and increase the D/U value. The first side lobe level

should be less than 18dB. For the BTS antenna based on major cell

system, this requirement is not imposed.


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Electric down tiltElectric down tilt

Mechanical down tiltMechanical down til t

Mechanical Down Tilt and Electric Down Tilt

Three kinds of methods and their combinations are usually used for

antenna beam downtilt: Mechanical downtilt, preset electricity downtilt and

electrically controlled downtilt (for electrically controlled antennas). During

adjustment of the electrically controlled antenna downtilt angle, the

antenna itself will not move, but the phase of the antenna dipole is

adjusted through electricity signals to change the field intensity so that the

antenna emission energy deviates from the zero-degree direction. The

filed intensity of the antenna is increased or decreased in each direction

so that there will be little change in the antenna pattern after the downtilt

angle is changed. The horizontal semi-power width is unrelated with the

downtilt angle. However, during mechanical adjustment of the downtilt

angle, the antenna itself will be moved. It is necessary to change the

downtilt angle by adjusting the location of the back support of the antenna.

When the downtilt angle is very large, although the coverage distance in

the main lobe direction changes obviously, yet signals in the directionperpendicular to the main lobe almost keep not change, the antenna

pattern deforms seriously, and the horizontal beam width becomes

greater as the downtilt angle is increased. A preset downtilt antenna is

similar to an electrically controlled antenna in working principle, but a

preset angle can not be adjusted.


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The advantages of an electrically controlled antenna are as follows: When

the downtilt angle is very large, the coverage distance in the main lobe

direction will be shortened obviously and the antenna pattern will not

remarkably change, so the interference can be reduced. On the other

hand, mechanical downtilt may deform the pattern. The larger the angle is,

the more serious the deformation is. Hence it is difficult to control the

interference.

In addition, electrically controlled downtilt and the mechanical downtilt

have different influence on the back lobe. Electrically controlled downtilt

allows further control of the influence on the back lobe, while mechanical

downtilt enlarges the influence on the back lobe.

If the mechanical downtilt angle is very large, the emission signals of the

antenna will propagate to high buildings in backward direction through the

back lobe, thus resulting in additional interference.

In addition, during network optimization, management and maintenance,

when we need to adjust the downtilt angle of an electrically controlled

antenna, it is unnecessary to shut down the entire system. So we can

monitor the adjustment of the antenna downtilt angle using special test

equipment for mobile communication, so as to ensure the optimum value

of the downtilt angle value of the antenna.


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Questions

How are antennas categorized by emission direction, and by appearance?

What are electric indices of antenna?

What are mechanical indices of antenna?

Into which types does the distributed antenna system break down?


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Summary

Working principles of antenna

Categories of antenna

Electric indices of antenna

Mechanical indices of antenna

New technologies of antenna


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Absolute power(dBm)

The absolute power of RF signals is notated by dBm and dBW.

Their conversion relationships with mW and W are: e.g., the signal

power is x W, its size notated by dBm is:

For example, 1W=30dBm=0dBW.

Relative power(dB)

It is the logarithmic notation of the ratio of any two powers

For example If , so P1 is 3dB greater than P2

Introduction to Power Unit

=

mw

mwPWdBmp

1

1000*lg10)(

=

mWP

mwPdBp

2

1lg10)(

wP 21 = wP 12 =

Most spectrum analyzers use the dB notation to display the measurement

results. dB is so popularly used because it can use the logarithmic mode

to compress the signal level that changes in a wide range. For example,

1V signal and 10uV signal can appear on the monitor whose dynamic

range is 100dB, while the linear scale cannot display the two signalssimultaneously in a clear picture. Therefore, dB is determines the power

ratio and voltage ratio in the logarithmic mode. In this case, the

multiplication operation changes to convenient addition operation. It is

typically used in calculating the gain and loss in the electronic systems.


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Noise

Noise means the unpredictable interference signal that occur during the

signal processing (the point frequency interference is not counted as noise)

Noise figure

Noise figure is used for measuring the processing capability of the RF

component for small signals, and is usually defined as: output SNR divided

by unit input SNR.

NF

Si

Ni

So

No

Noise-Related Concepts

Typical noises are: external sky and electric noise, vehicle start-up noise,

heat noise from inside systems, scattered noise of transistor during

operation, inter-modulation product of signal and noise.


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Noise figure formula of cascaded network

G1 NF1 G2 NF2 Gn NFn


1211

21

...

1...

1

++

+=

n

ntotal

GGG

NF

G

NFNFNF

As seen from the above formula, in the system noise, the noise figure of

the level-1 component imposes the greatest influence, the noise figure of

level-2 component imposes less influence, and so on. This explains why

the cascaded noise figure is reduced after installing the tower amplifier.

Usually, the NF of TMA is 1.5 . The NF of the level-1 component of BTSis 2.2 .


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Receiving Sensitivity

Receiving sensitivity

Expressed with power:

Smin=10log(KTB)+ Ft +(S/N), unit: dBm

K is a Boltzmann constant, unit: J/K (joule /K) , K=1.38066*10-19 J/K

T represents absolute temperature, unit: K

B represents signal bandwidth, unit: Hz

Ft represents noise figure, unit: dB

(S/N) represents required signal-to-noise ratio, unit: dB

If B=1Hz, 10log(KTB)=-174dBm/Hz

Receiving sensitivity refers to the minimum receiving signal strength

under a certain signal-to-noise ratio. It is an index that reflects the

receiving capability of the equipment.


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Tower Mounted Amplifier

Enlarge uplink signal, but its a loss

for downlink

Duplexer

Sharing antenna for receiving and

transmitting

Sharing antenna for multi-system

RF Components

The core of a TMA is a low noise amplifier, which can be used to solve a

limited uplink coverage problem and increase the uplink coverage area. For

uplink, the gain is around 13dB. For downlink, the loss is around 0.3dB.

Duplexer : A device that permits the simultaneous use of a transmitter and a

receiver in connection with a common element such as an antenna system.


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Splitter

Coupler

RF Components

Both couplers and power splitters are components for power distribution. The

difference is: a power splitter is for equal power distribution, while a coupler

is for non-equal power distribution. Therefore, couplers and power splitters

are used in different applications. In general, to distribute power to different

antennas within the same storey, a power splitter is used; to distribute powerfrom the trunk to tributaries of different stories, a coupler is used.

If couplers and power splitters are used in coordination, the transmit power

of the signal source can be distributed as evenly as possible to various

antenna ports of the system, namely, the transmit power of each antenna in

the entire distribution system is almost the same.

During power splitter selection, priority should be given to 1/2 power splitters,

not 1/4 power splitters. When using a 1/3 power splitter, make sure that the

power splitter is not too close to the antenna, and the feeder cable

connecting them should be over 20m long.


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Tx/Rx

Trunk

Trunk

Splitter

Trunk

Coupler

Splitter

Splitter

Splitter

Splitt

er

Splitter

Coupler

Coupler

Splitter

Splitter

Distribution System

In the tunnel/subway/indoor, if we cover it just by outdoor NodeBs, because

of the blocking of the obstacle, the QoS will be very bad, even cause call

drop. In addition, in large building, we usually use micro cell system to cover

it. But the indoor environment is different with outdoor and it is hard to use

one fixed antenna to cover the whole building because of the blocking of thewall and other obstacle. The indoor distribution system (IDS) can solve these

problems and increase the coverage of the micro NodeB. So the IDS is

necessary in some buildings.

In general, when selecting feeder cable types, select 7/8" cable for the trunk,

and 1/2" common cables or super flexible cable for tributaries. During the

trunk cabling process, if the curvature radius does not meet the requirement,

the trunk can be disconnected at corners, and a section of 1/2" super flexible

cable can be used for cabling around the corners.


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Summary

Definition about dBm, dB


Receiving Sensitivity

RF Components

SummarySummary


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Ec

Average energy per Chip

Not considered individually, but used for Ec/Io

Pilot Ec is measured by the UE (for HO) or the Pilot scanner, in the form

of Received Signal Code Power (RSCP)

For CPICH Ec:

Depends on power and path loss.

Constant for a given power and path loss. Ec is not dependent on

load

For DPCH Ec:

Depends on power and path loss

Symbol Explanation

The same could be said for the Dedicated Channel as for the pilot. The

Ec remains constant for a given power and path loss. The main difference

between the pilot and the DCH is that the DCH is power controlled.


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Eb

Average energy per information bit for the PCCPCH, SCCPCH, and DPCH, at the

UE antenna connector.

Typically not considered individually, but used for Eb/Nt

Depends on channel power (can be variable), path loss, and spreading gain (Gp)

Constant for a given bit rate, channel power, and path loss

Can be estimated form Ec and processing gain

Speech 12.2kbps example

Ec = -80 dBm

12.2kbps data rate => Processing gain = 24.98 dB

Eb~ -80 + 24.98 = -55.02 dBm

Symbol Explanation


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Io

The total received power spectral density, including signal and

interference, as measured at the UE antenna connector.

Similar to UTRA carrier Receive Strength Signal Indicator (RSSI), at

least for practical consideration (SC scanner)

RSSI in W or dBm

Io in W/Hz or dBm/Hz

Measured by the UE (for HO) or Pilot scanner in the form of RSSI

Depends on All channel power, All cells, and path loss

Depends on same-cell and other cell loading

Depends on external interferences

Symbol Explanation

This is different form other Io definitions: other users interferences

Io = total receive power per-channel receive power

This latest definition of Io is more in line with the ISCP (Interference

Signal Code Power) defined in the standard


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No common RF definition Thermal noise density

Typically not considered individually, but used for Eb/No

Can be calculated

No = KT

K is the Bolzman constant, 1.38*10^-23

T is the temperature, 290 K

No = 174 dBm/Hz under typical conditions

Typically the bandwidth noise and the receiver noise figure are also considered

No = KTBNF, where NF is noise figure

To avoid confusion, NF should be used when referring to thermal noise

Symbol Explanation

For a WCDMA system, the bandwidth is 3.84Mcps. For WCDMA, the

typical noise figure is 3dB Uplink (NodeB, but Huaweis NodeB is 2.2 dB

in RND) and 7 dB downlink (UE). These figures should always be

checked against the vendor specification, because implementation affects

them

Based on the previous formula, this gives the total noise power (noise

floor) as

Uplink: -174+66+3= -105dBm (RTWP value without subscriber)

Downlink: -174+66+7= -101dBm

These values are not the receiver sensitivity but the power measured at

the reference point, in the absence of signal. As WCDMA allows the

extraction of signals below the noise floor, the sensitivity can not be

deducted from these values.


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No for WCDMA system Total one-sided noise power spectral density due to all noise sources

Typically not considered individually, but used for Eb/No

Defined this way, No and Io are substituted for one another:

On the uplink the substitution is valid

On the downlink, differentiating between Noise and Interference is more

challenging

Symbol Explanation

Originally, Eb/No meant simply bit energy divided by noise spectral

density. However, over time the expression Eb/No has acquired an

additional meaning. One reason is the fact that in CDMA the interference

spectral density is added to the noise spectral density, since the

interference is noise, due, for example, to spreading. Thus, No canusually be replaced by Io, interference plus noise density.


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RTWP

Received Total Wide Bandwidth power

To describe uplink interference level

When uplink load increase 50%, RTWP value will increase 3dB

RSSI

Received Signal Strength Indicator

To describe downlink interference level at UE side

Symbol Explanation


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RSCP

Revived Signal Code Power (Ec)

Ec/Io = RSCP/RSSI, to describe downlink CPICH quality

ISCP

Interference Signal Code Power; can be estimated by:

ISCP = RSSI RSCP

Symbol Explanation


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Summary

Ec, Eb, Io and No

RTWP, RSSI, RSCP and ISCP

SummarySummary


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Documents

001 WCDMA RNP Fundamental