005 WCDMA RNP Fundamental

7/30/2019 005 WCDMA RNP Fundamental

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HUAWEI Mexico Training Center 1

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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Chapter 1 Radio Wave IntroductionChapter 1 Radio Wave Introduction

Chapter 2 AntennaChapter 2 Antenna

Chapter 3 RF BasicsChapter 3 RF Basics

Chapter 4 Symbol ExplanationChapter 4 Symbol Explanation


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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 frequencyresources 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 a good tradeoff between thecoverage 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 free space propagation. One isperpendicular 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 from time to time for

weather reasons. Its reflectance decreases with the increase of height. Thisslowly 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 ionosphere also presents the continuous fluctuation feature.


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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 thetransmitter 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 shortwave radio 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 differencebetween 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 the receiving

signal strength decreases but the field strength mid-value changes slowly with

the change of the topography, the strength decrease is called slow fading orshadow fading. The field strength mid-value of slow fading takes on alogarithmic normal distribution, and is related to location/locale. The fading

speed is dependent on the speed of the mobile station.

Fast fading: In case the amplitude and phase of the combined wave change

sharply with the motion of the mobile station, the change is called fast fading.The spatial distribution of deep fading points is similar to interval of half of

wavelength. Since its field strength takes on Rayleigh distribution, 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 causes Doppler effect

on the frequency domain, and thus results in frequency diffusion, time-selectivefading will occur.

Space-selective fading: The fading features vary between different places and

different transmission paths.

Frequency-selective fading: The fading features vary between different

frequencies, which results in delay diffusion and frequency-selective fading.


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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 andthe 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 receiver scapability 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 lightproblem), 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 of the same obstacle for the longwavelength 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 topographic conditions. For example, theOkumura 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 above example, the 1900MHz loss will be6dB 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 and environments, and developed aseries 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 extendthe 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 environment features 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 hilly terrains environments under it is LOSbetween 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 the actual value with the forecast value, weadjust 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 to the sampling rate of 1point/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 beinconsistent 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 deeply faded 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, and will result

in multiple test data at one location point. Suppose the vehicle runs at equal

speeds, such data should be distributed to the two fixed points on average, which

is a process of data dispersion. The main function of geographic averaging is to

eliminate the influence of fast fading 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 ofthe 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 polarization antennas. Thepolarization 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 important and difficult issues in the WCDMA airinterface, 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 irepresents Isotropic.dBd is defined as the energy centralization

capability of the actual direction antenna (including omni antenna) relative to thehalf-wave dipole antenna, where drepresents 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 the service are more

even, the first zero point of the lower side lobe should be filled, rather thanleaving 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 than18dB. 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 signalsto 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 direction perpendicularto 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 signals simultaneously 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,

intermodulation 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 BTS is 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 power from 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 the wall 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 ofsignals 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 can usually be replaced by Io, interference plus noisedensity.


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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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Thank You

005 WCDMA RNP Fundamental

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