WCDMA RAN Planning and Optimization (Book2 Design and Planning)

www.huawei.com

Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.

WCDMA RNP Fundamental


ObjectivesUpon 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.


Contents1. Radio Wave Introduction

2. Antenna

3. RF Basics

4. Symbol Explanation



1.1 Basic Principles of Radio Wave

1.2 Propagation Features of Radio Wave

1.3 Propagation Model of Radio Wave

1.4 Correction of Propagation Model


Radio Wave SpectrumRadio Wave Spectrum

The frequencies in each specific band present unique propagation features.

300-3000GHz

EHFExtremely HighFrequency

30-300GHzSHFSuper High Frequency3-30GHzUHFUltra High Frequency300-3000MHzVHFVery High Frequency30-300MHzHFHigh Frequency3-30MHzMFMedium Frequency300-3000KHzLFLow Frequency30-300KHzVLFVery-low Frequency3-30KHzVFVoice Frequency300-3000Hz

ELFExtremely LowFrequency

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 a good 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.


Propagation of Electromagnetic Wave

electric wave transmission directionElectric FieldElectric Field

Magnetic FieldMagnetic Field

Electric Field

Dipole

When the radio wave propagates in the air, the electric field direction

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

the ground, 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

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.


Perpendicular incidence wave and 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 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 from time 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 ionosphere also presents the continuous fluctuation feature.


①① Building reflection waveBuilding reflection wave②② Diffraction waveDiffraction wave③③ Direct waveDirect wave④④ 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.


Radio Propagation EnvironmentRadio 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.


Quasi-smooth landform

The 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”.


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” or “shadow fading”. The field strength mid-value of slow fading takes on a logarithmic 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-selective fading 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.

In order to mitigate the influence of fast fading on wireless communication, typical methods are: space diversity, frequency diversity, and time diversity.


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 receiver handles 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 receiver’s 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,

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 channel works at a broad band (WCDMA has a band of 5MHz), the communication itself is a kind of spreading communication.


Solution RAKE technologyRAKE technology

Radio Wave Delay ExtensionDeriving 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 thereceiving antenna

Radio wave delay extension—Another 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.


T

R

Diffraction LossThe electromagnetic wave diffuses around at 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 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.


Penetration Loss

XdBmWdBm

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

Penetration loss caused by obstructions:

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


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.


Lo=91.48+20lgd, for f=900MHzLo=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 be 6dB more than the 900MHz loss.


Ploss = L0+10χlgd -20lghb - 20lghm

χ ： 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.


Application ScopeApplication Scope

CharacteristicCharacteristic

Frequency range f:150~1500MHzBTS antenna height Hb:30~200mMobile station height Hm:1~10mDistance d:1~20km

Macro cell modelThe BTS antenna is taller than the surrounding buildingsPredication is not applicable in 1kmNot 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 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.



Frequency range f:1505~2000MHzBTS antenna height Hb:30~200mMobile station height Hm:1~10mDistance d:1~20km


Macro cell modelThe BTS antenna is taller than the surrounding buildingsPredication is not applicable in 1kmNot applicable to the circumstance where the frequency is above 2000MHz 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.



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 Hatamodel, and works out the frequency coverage extends from 1500MHz to 2000MHz by using some correction items. However, in all the testenvironments, 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 Walfish’s calculation of the urban environment, the Ikegami’s 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 α ( ° )


K1: Propagation path loss constant valueK2: log(d) correction factorD: Distance between receiver and transmitter (m)K3: log(HTxeff) correction factorHTxeff: Transmitter antenna height (m)K4: Diffraction loss correction factorK5: log(HTxeff)log(D) correction factorK6: Correction factor

: Receiver antenna height (m)Kclutter: clutter correction factor

( ) ( )( ) ( ) ( ) ( )clutterfKHKHDK

lossnDiffractioKHKDKKPathLoss

clutterRxeffTxeff

Txeff

++×+

×+++=

65

4321

loglog

loglog

RxeffH

Experimental formulaExperimental formula

Explanation Explanation

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 LOS between transmitter and receiver.


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, we adjust the parameters in the model. The process recurs until the error meets the requirements.


5m

Site SelectionCriteria for selecting a site

The antenna height is greater than 20m

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

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. Thebuilding serving as a site should be taller than the average height of the surrounding buildings


Transmitting subsystems

Transmitting antenna, feeder, high-frequency signal source, antenna

bracketOmni-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.


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.


Rules of selecting a test pathLandform: 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 1 point/6m after smoothing the sampling data, it takes at least 60km as a test distance for 10000 sampling points.


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


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

sampling points

Upper limit of drive speed: Vmax=0.8λ/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

Sampling distance: The distance between adjacent sampling points should be λ-λ/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


Test Data ProcessingThe 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

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 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

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.



2. Antenna

3. RF Basics



Positions and Functions of Antenna

Lightning protection device

main feeder (7/8“)

Feeder clip

Cabling rack

Grounding device

3-connector seal component insulation sealing tape, PVC

insulation tape

Antenna adjustment bracket

GSM/CDMAplate-shape

antenna

radio mast (φ50~114mm)

Outdoor feeder

Indoor super flexible feeder

Feeder cabling window

main device of 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; andconverts the electromagnetic wave to high-frequency current when receiving. Other parts of the antenna & feeder are shown in the diagram.


omni antenna

AntennaConnector

Dipole

Feed network

AntennaConnector

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.


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.


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.


Omni antenna Uni-polarization Directional antenna

Dual 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. 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.


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 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.


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)


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.


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.


dBi与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 energy centralization capability of the actual direction antenna (including omniantenna) relative to the half-wave dipole antenna, where “d” represents “Dipole”.


Antenna Pattern

Antenna pattern

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


Antenna Pattern

Side lobe Zero point

fillingMain 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 180°±30°. 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 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

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.


Electric down tiltElectric down tilt

Mechanical down tiltMechanical down tilt

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 direction perpendicular 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.

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.



2. Antenna

3. RF Basics



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

⎟⎠⎞

⎜⎝⎛=

mwmwPWdBmp

11000*lg10)(

⎟⎟⎠

⎞⎜⎜⎝

⎛=

mWPmwPdBp

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.


NoiseNoise means the unpredictable interference signal that occur during the signal processing (the point frequency interference is not counted as noise)

Noise figureNoise 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

SiNiSoNo

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.


Noise figure formula of cascaded network

Noise-Related Concepts

1211

21

...1...1

−⋅⋅⋅−

++−

+=n

ntotal

GGGNF

GNFNFNF

G1 NF1 G2 NF2 Gn NFn

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 .


Receiving SensitivityReceiving sensitivity

Expressed with power:

Smin=10log(KTB)+ Ft (NF) +(S/N), unit: dBmK 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.


Tower Mounted Amplifier

Enlarge uplink signal, but it’s 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.


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.


Tx/Rx

Trunk

Trunk

Splitter

TrunkC

oupler

Splitter

Splitter

SplitterSplitter

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.



2. Antenna

3. RF Basics



Symbol ExplanationEc

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, inthe 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 onload

For DPCH Ec:Depends on power and path loss

The same could be said for the Dedicated Channel as for the pilot. The Ecremains constant for a given power and path loss. The main difference between the pilot and the DCH is that the DCH is power controlled.


Symbol ExplanationEb

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 gainSpeech 12.2kbps example

Ec = -80 dBm

12.2kbps data rate => Processing gain = 24.98 dB

Eb~ -80 + 24.98 = -55.02 dBm


Symbol ExplanationIo

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

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


Symbol ExplanationNo common RF definition

Thermal noise densityTypically not considered individually, but used for Eb/NoCan 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

For a WCDMA system, the bandwidth is 3.84Mcps. For WCDMA, the typical noise figure is 3dB Uplink (NodeB, but Huawei’s 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.


Symbol ExplanationNo 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

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 noise density.


Symbol ExplanationRTWP

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 ExplanationRSCP

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

Thank youwww.huawei.com

www.huawei.com


WCDMA Radio Network Coverage Planning



Know the contents and process of radio network planning

Understand uplink budget and related parameters

Understand downlink budget and related parameters


Contents1. WCDMA Radio Network Planning Process

2. R99 Coverage Planning

3. HSDPA Coverage Planning


Capacity, Coverage, QualityCapacity & Coverage

↑ Users ↑ Cell Load ↑ Interference Level ↓ Cell Coverage

↑ Cell Coverage Cell Load ↓ Capacity ↓

Capacity & Quality↑ Users ↑ Cell Load ↑ Interference Level ↓ Quality

↑ Quality ( BLERtar ↓ ) ↓ Capacity

Coverage & Quality

↑ Quality ( AMR ↑ ) ↓ Cell Coverage

Capacity

Quality Coverage

COST

Capacity–coverage (typical case: downlink load balance)

Capacity–quality (typical case: lowering BLER through outer loop power control)

Coverage–quality (typical case: lowering the data rate of the connections with much path loss through AMRC)


WCDMA Radio Network Planning Process

Radio Network Planning (RNP) Process

Step1 : Radio network dimensioning

Step2 : Pre-planning of radio network

Step3 : Cell planning of radio network

3G radio network planning can be divided into three phases. They are shown in above figure, and consist of dimensioning, pre-planning and cell planning.

According to the above figure, the output result of radio network dimensioning stage serves as the input condition of the pre-planning, and the pre-planning is based on the network dimensioning and also checks the network dimensioning result. The site quantity can be adjusted according to the pre-planning result in order to obtain the reasonable sites. If the existing sites are considered in the selection of theoretical sites during the pre-planning, the pre-planning result will be more practical, thus facilitating the cell planning.



Step1 : Radio network dimensioning

Radio network dimensioning includes coverage

dimensioning and capacity dimensioning

Obtain the scale of sites and configuration according to

input requirements when the coverage and capacity are

balanced

Radio Network Dimensioning is a simplified analysis for radio network

Dimensioning provides the first and most rapid evaluation of the network element number as well as the associated capacity of those elements. The target of dimensioning phase is to estimate the required site density and site configurations for the area of interest. Dimensioning activities include radio link budget and coverage analysis, capacity evaluation and final estimation of the amount of NodeB hardware and E1, cell average throughput and cell edge throughput.

Objective:

To obtain the network scale ( approximate NodeB number and configuration)

Method:

Select a proper propagation model, traffic model and subscriber distribution, and then estimate the NodeB number, coverage radius, E1 number per site, cell throughput, cell edge throughput and so on.



Input & output of radio network dimensioning

Capacity Related-Spectrum Available-Subscriber Growth Forecast-Traffic Density

Coverage Related-Coverage Region

-Area Type Information-Propagation Condition

QoS Related-Blocking Probability-Indoor Coverage

Input

Number of NodeB

Carrier configuration

CE configuration

Iub configuration

……

-Coverage Probability

The service distribution, traffic density, traffic growth estimates and QoS requirements are already essential elements in dimensioning phase. Quality is taken into account here in terms of blocking and coverage probability.



Step2 : Pre-planning of radio network – Initial Site Selection

Based on RND, radio network pre-planning is intended to

determine:

Theoretical location of sites

Implementation parameters

Cell parameters

Wireless network dimensioning intends to obtain the approximate UTRAN scale. Based on the network dimensioning, geography and traffic distribution, the network is pre-planned in detail by using planning software and digital map.

Based on the network dimensioning and site information, the initially selected WCDMA site is imported into the planning software, and coverage is estimated by parameters setting. Then an analysis is made to check whether the coverage of the system meet the requirements. If necessary, the height and tilt of the antenna and the NodeB quantity are adjusted to optimize the coverage. And then the system capacity is analyzed to check whether it meets the requirement.

Implementation parameters, such as antenna type / azimuth / tilt / altitude / feeder type / length …

Cell parameters, such as transmission power of traffic channel and common channel, orthogonal factor, primary scrambling code…



Step2 : Pre-planning of radio network - Prediction

Based on RND result, sites location, implementation parameters and cell parameters, we should predict coverage results such as best serving cell, pilot strength, overlapping zone

We should carry out detailed adjustment (such as NodeB number, NodeB configuration, antenna parameters) after analyzing the coverage prediction results

Finally ,we obtain proper site location and parameters that should satisfy coverage requirement

Based on the network dimensioning and site information, the initially selected WCDMA BS is imported into the planning software, and coverage is estimated by setting the cell parameters and engineering parameters. Then an analysis is made to check whether the coverage of the system meet the requirements. Then the system capacity is analyzed to check whether it meets the requirement. If necessary, the height and tilt angle of the antenna and the BS quality are adjusted to optimize the coverage.



Step2 : Pre-planning of radio network - Prediction

Coverage by transmitter:Display the best server coverage

Coverage by signal level: Display the signal level across the studied area

Overlapping zones:Display the signal level across the studied area

These graphs are prediction results of Huawei planning tool: U-Net

For the result of coverage prediction, focus on the distribution of best servers and pilot level. For the small areas with unqualified level, adjust the azimuth and down tilt to improve the coverage. For the large areas with weak coverage, analyze whether the site distance is over large:

If yes, add sites to improve coverage.

If no, check whether the configuration of parameters related to coverage prediction is correct.



Step3 : Cell planning of radio network - Site Survey

We have to select backup location for site if theoretical location

is not available

Based on experience , backup site location is selected in

search ring scope , search ring =1/4×R

We should consider other factors when we select the backup sites

Commercial factor: rent

Radio propagation factor: situation / height / surrounding /

Implementation factor: space / antenna installation / transmission / power supply



Step3 : Cell planning of radio network – Simulation

U-Net use Monte Carlo simulation to generate user

distributions (snapshots)

By iteration, U-Net get the UL/DL cell load, connection status

and rejected reason for each mobile

The example of Monte Carlo simulation:

Simulation is oriented to simulate the running situation of networks under the current network configuration so as to facilitate decision-making adjustment. Now there are two system simulation classes: static simulation and dynamic simulation.

Static simulation focus on user behavior such as browsing Internet, call. It would gain the performance of radio network based on “snapshot”.

Dynamic simulation focus on detail of user behavior such as duration and data rate of browsing. It would gain the performance of radio network based on analysis of mobile subscribers. But it requires higher precision of e-map.

At present, Static simulation is in common use. Monte Carlo simulation is one type of static simulation.



The following takes coverage probability for an example to

further understand how Monte Carlo simulation is performed

100%100% 100%100%20%20% 60%60%

0%0% 75%75% 40%40%60%60%

Simulation result

1st snapshot

3rd snapshot

2nd snapshot



Step3 : Cell planning of radio network – Simulation

Generate certain quantity of network instantaneous state (snapshot)

Obtain connection performance between terminals and UTRAN by

incremental operation

Some UEs or terminals are distributed based on a certain rule (such as random even distribution) at each “snapshot”

It is required to consider the possibility of multiple connection failure (uplink/downlink traffic channel maximum transmit power, unavailable channels, low Ec/Io and uplink/downlink interference



Step3 : Cell planning of radio network - Simulation

Measure and analyze results of multiple “snapshots” to have a

overall understanding of network performance

Handover Status:Display areas depending on the probe mobile handover status

Pilot Quality (Ec/Io):Displays the pilot quality across the certain area

Pilot Pollution:Displays pilot pollution statistics across the certain area

These graphs are prediction results (based on simulation) of Huawei planning tool: U-Net

The previous predictions (Coverage by transmitter, Coverage by signal level, Overlapping zones) are based on coverage, the predictions in this slide are based on simulation.


Contents2. R99 Coverage Planning

2.1 Process of R99 Coverage Planning

2.2 R99 Uplink Budget

2.3 R99 Downlink Budget


Process of R99 Coverage PlanningGoal of R99 coverage planning

obtain the cell radius

estimate NodeB number that could satisfy coverage

requirement Start

Link Budget

Cell Radius

NodeB Coverage Area

NodeB Number

End

Propagation modelPath Loss

R

R23*

89 RArea =

23*23 RArea =

area coverage NodeBarea coverage Total

number NodeB

=

In the coverage dimensioning, the link is estimated according to elements such as planned area, network capacity, and equipment performance in order to obtain the allowed maximum path loss. The maximum cell radius is obtained according to the radio propagation model and allowed maximum path loss. And then the site coverage area is calculated. Finally, the site quantity is calculated. Of course, the site quality is only for the ideal cell status, and some additional sites will be needed in actual terrain environment.


Uplink Budget Principle

Path Loss

Cable Loss

Antenna Gain

NodeBSensitivity Penetration

Loss

UE Transmit Power

UE Antenna Gain

NodeB Antenna Gain

SHO Gain against fastfading

SHO Gain against Slowfading Slow fading margin

Fast fading margin

Interference margin

Body Loss

Cable Loss

Penetration Loss

MaximumAllowed path loss

UPLINK BUDGET

Antenna Gain

NodeB reception sensitivity

SHO Gain

Margin

Loss

Link dimensioning intends to estimate the system coverage by analyzing the factors of the propagation channels of the uplink signal and downlink signal. It is the link analysis model.

If the parameters such as transmit signal power, gain and loss of the transmitter and receiver, and quality threshold of received signal are known or estimated, the allowed maximum path loss used for ensuring the quality of received signal can be calculated.


Element of Uplink Budget1. UE_TransmissionPower ( dBm )

The UE maximum transmit power is determined by the power class

of the UE, which is specified by the 3GPP standard

The Class 4 UE, with maximum power 21 dBm, are normally

considered due to their popularity in the market

Grade of UE power （TS 25.101 )

+2/-2dB+21dBm4

+1/-3dB+24dBm3

+1/-3dB+27dBm2

+1/-3dB+33dBm1

ToleranceNominal maximum output powerPower Class

In network planning, the value should be set according to the UE capacity with lowest power grade in the commercial network of the operator.

Note that it is possible that a UE supporting high-speed uplink data service (higher than 64kbps) has a higher power grade than a UE supporting only voice and low-speed data services, for example, power grade 3dBm ～ 24dBm.

With a higher maximum power rating, the maximum path loss is increased accordingly. This allows the operator to plan cells with a relatively larger coverage.

The UE cable loss, connector loss, and combiner loss are quite negligible, hence a 0 dB loss is assumed here。


Element of Uplink Budget2. Body Loss ( dB )

For voice, the body loss is 3 dB

For the other service , the body loss is 0 dB

3. Gain of UE TX Antenna ( dBi )

In general, the gain of UE antenna is 0 dBi

The 0 dBi antenna gain is considered here with respect to the internal antenna of mobile phones.


Element of Uplink Budget4. Penetration Loss ( dB )

Indoor penetration loss means the difference between the

average signal strength outside the building and the average

signal strength of first floor of the building

In terms of service coverage performance, micro-cells provide

an effective solution for achieving a high degree of indoor

penetration

The penetration loss is related to building type, incidence angle of the radio wave and so on. In the link budget, assume that the penetration loss obey the Log-Normal distribution. The penetration loss is related to mean value of penetration loss and standard deviation

When indoor coverage is required to coverage by outdoor macro NodeBs, building penetration loss needs to be considered. Building penetration loss is related to such factors as incidence angle of the radio wave, the building construction (the construction materials and number and size of windows), the internal building layout and frequency. Building penetration loss is highly dependent on specific environment and morphology and varies greatly. For instance, the wall thickness in Siberian tends to be larger than that of Singapore in order to resist coldness and hence the former’s building penetration loss is correspondingly larger.

In addition, sometimes vehicular coverage may be required and consequently vehicular penetration loss also needs to be included in link budget process. typical vehicular penetration loss is around 8dB.


Element of Uplink Budget5. NodeB_AntennaGain ( dB )

6. Cable loss ( dB )- Cable loss between NodeB and antenna

- Jumper loss between NodeB and antenna

- Connectors loss between NodeB and antenna

206 Sector183 Sector182 Sector11OmniGain of Antenna (dBi)Sector Type

Cab

le L

oss

Antenna gain: It refers to the ratio of the square of the actual field of an antenna at a point in the space to the square of the field of an ideal radiation unit at the same point in the space, namely power ratio. It is the gain in the main transmit direction. In general, the gain is related to the antenna pattern. If the central lobe is narrow and the back lobe and side lobe are small, the gain is high. If the transmit direction is centralized, the antenna gain is high. For an omnidirectional antenna, the gain in all the directions is the same.

Front-to-back ratio: It refers to the ratio of the maximum gain in the principal direction to the gain in the reverse direction. It describes the directing feature. If it is high, the directed receive performance of the antenna is high.

Beam width: It refers to the separation angle between the main transmit direction of the power and the point with 3 dB of transmit power reduced, and the area is called an antenna lobe. Tilt: It refers to the tilt angle of a directional plate antennal. It is used to control interference and improve coverage.

Polarization: The vector direction of the electrical field in the direction with the highest radiation. A dual polarized antenna can provide diversity over a single antenna, thus saving one antenna.

In general, there are two or more lobes in an antenna pattern. The largest lobe is the central lobe, and others are side lobes. The separation angle between the two half-power points of the central lobe is the lobe width of the antenna pattern, namely, half-power (angle) lobe width. If the central lobe is narrow, the directivity is high, and the anti-interference capability is high.


Element of Uplink BudgetPath Loss and Fading

Path Loss - fading due to propagation distance

Long term (slow) fading - caused by shadowing

Short term (fast) fading - caused by multi-path propagation

Radio propagation in the land mobile channel is characterized by multiple reflections, diffractions and attenuation of the signal energy. These are caused by natural obstacles such as buildings, hills, and so on, resulting in so-called multi-path propagation. Furthermore, with the moving of a mobile station, the signal amplitude, delay and phase on various transmission paths vary with time and place. Therefore, the levels of received signals are fluctuating and unstable and these multi-path signals, if overlaid, will lead to fading i.e. short term fading. The mid-value field strength of Rayleigh fading has relatively gentle change and is called “Slow fading”i.e. long term fading. And it conforms to lognormal distribution.

Long term fading– the variation of signal level is slow and smooth.

Short term fading– the variation of signal level is fast and poignant


Element of Uplink Budget7. Slow Fading Margin

Slow Fading Margin depends on

Coverage Probability @ Cell Edge

The higher the coverage probability is, the more SFM is required

Standard Deviation of Slow Fading

The higher the standard deviation is, the more SFM is required

Received Signal Level [dBm]

Pro

babi

lity

Den

sity

Fthreshold

Coverage Probability @ Cell Edge:

P COVERAGE (x) = P [ F(x) > Fthreshold ]

Coverage Probability @ Cell Edge:

P COVERAGE (x) = P [ F(x) > Fthreshold ]

SFM required

Without SFM

With SFM

Slow Fading --- Signal levels obey Log-Normal distribution

Propagation models predict only mean values of signal strength , the mean value of signal strength fluctuates. The deviation of the mean values has a nearly normal distribution in dB, The variation in mean values is called log-normal fading.

Probability that the real signal strength will exceed the average one on the cell border is around 50%,for higher than 50% coverage probability an additional margin has to be introduced. The margin is called slow fading margin.

Slow Fading Margin (SFM) is related with coverage probability in cell edge and standard deviation of slow fading. The equation is described as following:

The standard deviation is a measured value that is obtained from various clutter types. It basically represents the variance (log-normally distributed around the mean value) of the measured RF signal strengths at a certain distance from the site.

Therefore, the standard deviation would vary by clutter type. Depending on the propagation environment, the log-normal standard deviation can easily vary between 6 and 8 dB or even greater. Assuming flat terrain, rural or open clutter types would typically have lower standard deviation levels than the suburban or urban clutter types. This is due to the highly obstructive properties encountered in an urban environment that in turn will produce higher standard deviation to mean signal strengths than that experienced in a rural area. Standard Deviation of slow fading is related with morphology, frequency and environment. For instance:


Element of Uplink Budget8. SHO Gain against Slow Fading

SHO reduces slow fading margin compared to the single cell case

SHO gain against slow fading can improve the coverage probability

SHO Gain against slow fading = SFM without SHO - SFM with SHO

SHO Gain Against SFM

0

1

2

3

4

5

6

7

98% 95% 92% 90% 85%Standard deviation=11.7Path loss slope=3.52 Area coverage probability

(dB)

Soft Handover --- handover between different NodeBs

Softer Handover --- handover between cells in a NodeB

SHO gain over slow fading is also known as the Multi-Cell gain because in soft handover more than 1 branch exists and hence the coverage probability increases which would result in the decreasing of required slow fading margin.

Suppose that soft handover has 2 branches, and the orthogonality of the two radio link branches on slow fading is 50%. We can calculate the slow fading margin required with soft handovers based on the former assumptions, and compare it with the slow fading margin required without soft handover to get the SHO gain over slow fading.

SHO gain over slow fading is dependent on the required area coverage probability, the propagation path loss slope and the STD. The following table gives the calculated SHO gain over slow fading and the propagation path loss slope equals to 3.59.


Element of Uplink Budget9. Fast Fading Margin

Fast fading margin

required to guarantee fast power control

the factors affect FFM include channel model, service type, BLER

requirement

Uplink case: UE moves towards the edge of the cell

Fast Fading Margin= Eb/No without fast PC - Eb/No with fast PC

Fast power control

to enhance weak signal caused by Rayleigh fading

to mitigate interference and enhance the capacity

to promote power utilization efficiency

In WCDMA, user signals should be received at the NodeB with equal power all the time and for downlink the transmitted TCH power should be as small as possible while maintaining the required Qos. This implies that fast fading are compensated by the power control algorithm, which requires additional headroom at both UE and NodeB in order to let UE and NodeB following the power control commands at cell edge.


Element of Uplink Budget10.SHO Gain against Fast fading

SHO gain against fast fading reduces the Eb/No requirement

SHO gain against fast fading leads to a gain for reception

sensitivity

SHO gain against fast fading exists for both uplink and

downlink (Typical value of SHO gain against FFM is 1.5dB)

SHO Gain Against Fast Fading = Eb/No without SHO – Eb/No with SHO

Because of the macro diversity combination, the soft handover reduces the required Eb/No by a single radio link, which results in additional macro diversity gain.


Element of Uplink Budget11. Interference Margin in Uplink

Interference Margin is equal to Noise Rise

Higher cell load leads to heavier interference

Interference margin affects cell coverage

( ) [ ]dBLogNoiseRise ULη−⋅−= 110 10

UL Load

Noi

seR

ise(

dB) Interference Curve in Uplink 50% UL Load — 3dB

60% UL Load — 4dB75% UL Load — 6dB

Interference margin is the required margin in the link budget due to the noise risecaused by system load (the noise rise due to other subscribers). The higher the system load is, the larger the interference margin should be.


Element of Uplink Budget12.NodeB Reception Sensitivity

Nth : Thermal Noise

NF: Noise Figure

Eb/No : required Eb/No to maintain service quality

PG: Processing Gain

PGNENFNsitivityceptionSen bth −++= 0/Re



Nth : Thermal Noise is the noise density generated by

environment and equals to:

K：Boltzmann constant, 1.38×10-23J/K

T：Temperature in Kelvin, normal temperature: 290 K

W：Signal bandwidth, WCDMA signal bandwidth 3.84MHz

Nth = -108dBm/3.84MHz

)**log(10 WTKN th =

If the W=1Hz, Nth=-174dBm/Hz

If the W=200kHz, Nth=-121dBm/200kHz



NF: Noise Figure :

For Huawei NodeB, latest NF is 1.6dB

For commercial UE, typical NF is 7dB.

Typical noises are: external sky and electric noise, vehicle start-up noise, heat noise from inside systems, scattered noise of transistor during operation, intermodulationproduct of signal and noise.

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

SiNiSoNo



PG: Processing Gain :

Processing gain is related with the service bearer rate, and the

detail formula is present below:

)rate bitrate chiplog(10Gain ocessPr =

For common services, the bit rate of voice call is 12.2kbps, the bit rate of video phone is 64kbps, and the highest packet service bit rate is 384kbps(R99). After the spreading, the chip rate of different service all become 3.84Mcps.



Eb/No is required bit energy over the density of total noise to maintain service quality

Eb/No is obtained from link simulation

Eb/No is related to following factors

Service type

Multi-path channel model

User speed

The target BLER

For instance:

6 dB2.3 dBRA120

5.4 dB2.5 dBTU31.00%CS64k

6.8 dB2.8 dBRA120

6.3 dB2.8 dBTU30.10%CS64k

8.3 dB4.5 dBRA120

7.8 dB5.4dBTU31.00%AMR12.2k

Downlink Eb/N0Uplink Eb/N0Channel ModelBLERService


Downlink Budget Principle

Path Loss

CableLoss

Antenna Gain

UESensitivity

PenetrationLoss

NodeB Transmit Power

UE Antenna Gain

NodeB Antenna Gain

SHO Gain against fastfading

SHO Gain against Slowfading Slow fading margin

Fast fading margin

Interference margin

Body Loss

Cable Loss

Penetration Loss

DOWNLINK BUDGET

Maximumallowed path loss

UE reception sensitivity

Antenna Gain

SHO Gain

Margin

Loss


Element of Downlink BudgetInterference Margin in Downlink

Wherein, is non-orthogonality factor, f is the interference

ratio of other cell to own cell

Interference margin is equal to noise rise

( )N

DLMax

N

otherownN

N

total

PCLPfNo

PIIP

PINoiseRise /ηα ⋅×++

=++

==

α

Interference Margin

0.00

5.00

10.00

15.00

20.00

25.00

30.00

120 125 130 135 140 145 150

IM(dB)

CL(dB)

=0.6, = 1.78,

PMax=20W,

α f

9.0=DLη

In case of multi-path propagation, certain energy will be detected by the RAKE receiver, and become interference signals. We define the orthogonal factor to describe this phenomenon. It is obtained through simulation, and related to environment type and cell radius.

α


Case Study : R99 Uplink Budget


Case Study : R99 Downlink Budget


Link Budget Difference of HSDPA and R99

Coverage Requirement

R99: Based on target continuous coverage service

HSDPA: Based on cell edge throughput

Simulation KPI

R99: Connect Success Rate, Coverage Probability, Pilot

Pollution Proportion and SHO

HSDPA: Cell Average Throughput and Cell Edge Throughput

Continuous coverage target service requirement with specific coverage probability

should be given for R99

Cell edge throughput requirement with specific coverage requirement should be given

for HSDPA



Target Network Load

R99: DL target load should be set to 75%

HSDPA: DL target load can be raised to 90%

time

R99 DCH Power

CCH

Cell total power

75%

More power to ensure R99 capacity

Cell total power

HSDPA power

90%

time

CCH

R99 DCH Power

The cell total transmit power is the constant resources. The DL power consists of the following three parts:

Power of the HSPA DL physical channel (HS-PDSCH, and HS-SCCH)

Common channel power

DPCH power



Other Parameters

R99:

Power control margin should be considered.

SHO gain should be considered.

HSDPA:

Power control margin need not be considered.

SHO gain should not be considered for HSDPA.

Other elements: Number of HS-PDSCH, HSDPA power, etc.

Fast power control

For R99, power control margin should be considered

For HSDPA, the maximum transmission power for HS-PDSCH is the

remaining power excluding R99 power and power margin, and no power

control margin

SHO gain

For R99, SHO gain should be considered

For HSDPA, only hard handover, no SHO gain

HSDPA related parameters should be configured when simulation

Max number of HS-PDSCH channel

Min number of HS-PDSCH channel

HSDPA power allocation, dynamic or fixed

HS-SCCH power allocation, dynamic or fixed

Max number of HSDPA users

Scheduling Algorithm


HSDPA Deployment Strategy

Hot Spot & Dense Urban Urban Suburban & Rural

Initial Phase

Mature Phase

Focus on:HSDPA Performance

Focus on:

HSDPA coverage

no impact on R99

R99 f1

f2

R99+HSDPA R99

R99+HSDPA

HSDPA+R99

f1

f2

R99+HSDPA

HSDPA+R99

R99+HSDPA

HSDPA+R99

Single carrier for HSDPA and R99

Advantages

Maximum resource utilization efficiencySave cost

Disadvantages

Handover between HSDPA cell and R99 cell

Two carriers for HSDPA and R99

Advantages

Fewer inter-frequency handover for HSDPA userDisadvantages

High cost


HSDPA Link Budget Categories

HSDPA Throughput RequirementHSDPA+R99

HSDPA+R99

R99

No WCDMA

Guarantee R99 CS Traffic Capacity

Not Change R99 Coverage

HSDPA Throughput Requirement

R99/R4 Capacity, Coverage Requirement

R99 requirement should be met first, and then HSDPA throughput !

R99 and HSDPA requirement should be met simultaneously !

If operator wants to upgrade HSDPA from R99, R99 should be met first, and HSDPA should not affect the R99.

If operator setup R99 and HSDPA directly, R99 and HSDPA requirement should be met at the same time.


HSDPA Link Budget ElementDL Coupling Loss

Cell edge Ec/No

LpSFMLbantennaGaBSLfDLPLssCouplingLoDL NSHO +++−+= ____

( ))

10log(10

10_

max

NtNFCoupleLossDL

DL

DSCHHS

Pf

PNoEc

＋＋

+××+×= −

ηα

DL Coupling Loss :

PL_DL: Downlink path loss

Lf_BS: cable loss of NodeB

Ga_antenna: Gain of UE antenna and NodeB antenna

Lb: Body loss

SFMNSHO: Slow fading margin without soft handover

Lp: Penetration loss

Cell edge Ec/No:

PHS-DSCH : total power of HS-DSCH channel

: non-orthogonality factor

: neighbor cell interference factor

: downlink load factor including R99 and HSDPA service

Pmax : max transmission power of downlink

Nt : thermal noise power spectral density , typical value is -108.16dB

NF : receiver noise figure of UE, typical value is 7dB

α

f

DLη


HSDPA Link Budget PrincipleGoal of HSDPA link budget

The HSDPA link budget is usually based on the R99 link budget to get

the cell edge throughput in downlink

The HSDPA cell edge throughput need to be calculate depend on

simulation results, which is related with cell edge Ec/No

Simulation

Conditions

Channel model-TU3

5 codes

The theoretical maximum throughput is decided by the number of HSDPA codes.

For HSDPA , soft handover gain and fast fading margin should not be considered in link budget , since neither power control nor soft handover in HS-PDSCH channel


HSDPA Link Budget PrincipleAccording to R99 Cell Radius and HSDPA Power Allocation,

calculate Cell Edge Throughput

R99 Network Cell Radius

Downlink Path Loss

Ec/No at Cell Edge

HSDPA power

Cell Edge Throughput

Simulation Results

( ))

10log(10

10_

max

NtNFCoupleLossDL

DL

DSCHHS

Pf

PNoEc

＋＋

+××+×= −

ηα

DL_CoupleLoss=DL_PL+TxBodyLoss+TxCableLoss-TxAntennaGain+RxBodyLoss+ RxCableLoss-RxAntennaGain+PenetrationLoss+SlowFadingMargin

Downlink Coupling Loss

The step is present below:

According to the Cell Radius comes from R99 dimensioning, the Downlink Path Loss can be calculated

According to the Downlink Path Loss , the Downlink Coupling Loss can be calculated

According to the Downlink Coupling Loss and HS-DSCH Power, Cell Edge Ec/No can be calculated

According to the Cell Edge Ec/No and simulation result, Cell Edge Throughputcan be calculated


HSDPA Link Budget PrincipleAccording to Cell Edge Throughput requirement and HSDPA Power Allocation, calculate HSDPA Cell Radius


Ec/No at Cell Edge

Downlink Path Loss

HSDPA power

HSDPA Cell Radius

Simulation results

( )

NtNF

Pf

NoEc

P

CoupleLossDL

DLDSCHHS

＋

max

_

××+−

=

− ηα

DL_CoupleLoss=DL_PL+TxBodyLoss+TxCableLoss-TxAntennaGain+RxBodyLoss+ RxCableLoss-RxAntennaGain+PenetrationLoss+SlowFadingMargin



According to the Cell Edge Throughput and simulation result, Cell Edge Ec/Nocan be calculated

According to the Cell Edge Ec/No and HS-DSCH Power, the Downlink Coupling Loss can be calculated

According to the Downlink Coupling Loss, the Downlink Path Loss can be calculated

According to the Downlink Path Loss and and Propagation Model, HSDPACell radius can be calculated


HSDPA Link Budget PrincipleAccording to Cell Edge Throughput requirement and Cell Radius, calculate HSDPA Power


Ec/No at Cell EdgeDownlink Path Loss

Simulation results

( )SCCHHS

DL

SCCHHSDSCHHSHSDPA

PP

NoEcPfNFNtCoupleLossDL

PPP

−

−−

+×××++××

=

+=

max

max )_( ηα


Cell Radius

HSDPA Power


According to the Cell Radius comes from R99 dimensioning, the Downlink Path Loss can be calculated

According to the Downlink Path Loss , the Downlink Coupling Loss can be calculated

According to the Cell Edge Throughput and simulation result, Cell Edge Ec/Nocan be calculated

According to the Downlink Coupling Loss and Cell Edge Ec/No , HS-DSCH Power can be calculated


Case Study – HSDPA Link BudgetAssumption:

Downlink maximum path loss: 129.06 dB

Cable loss : 0.5 dB

NodeB antenna gain : 18dBi

Penetration loss : 20dB ( required in indoor coverage )

Body loss : 0 dB

Slow fading margin without soft handover gain against SFM :

13.1


Case Study – HSDPA Link BudgetAssumption:

Channel type: TU3

Non-orthogonality factor: 0.5

Adjacent cell interference factor: 1.78

HSDPA code resource: 5

Cell radius: 0.36 km

UE Category: 8

Max transmitter power of downlink: 20000 mW

Total power of HSDPA: 6000 mW (30% downlink power allocation)


Case Study – HSDPA Link BudgetAccording to the assumption above, the DL Coupling Loss for

HSDPA is calculated below:

Cell Edge Ec/No will be carry out base on equation below:

Base on the simulation result, the Cell Edge Throughput for

HSDPA can be obtained is 173.80 Kbps

144.66dB2013.1018-0.5129.06LpSFMLbantennaGaBSLfDLPLssCouplingLoDL NSHO

=++++=+++−+= ____

( )

dB

Pf

PNoEc

NtNFCoupleLossDL

DL

DSCHHS

2.10)1020000*9.0*)78.15.0(

6000log(*10

)10

log(*10

10716.10866.144

10_

max

−=++

=

+××+=

+−

−＋＋

ηα

www.huawei.com


WCDMA Radio Network Capacity Planning


ForewordWCDMA is a self-interference system

WCDMA system capacity is closely related to coverage

WCDMA network capacity has the “soft capacity” feature

The WCDMA network capacity restriction factors in the radio network part include the following:

Uplink interference

Downlink power

Downlink channel code resources (OVSF)

Channel element (CE)



Grasp the parameters of 3G traffic model

Understand the factors that restrict the WCDMA network capacity

Understand the methods and procedures of estimating multi-service capacity

Understand the key technologies for enhancing network capacity


Contents1. Traffic Model

2. Interference Analysis

3. Capacity Dimensioning

4. CE Dimensioning

5. Network Dimensioning Flow



1.1 Overview of traffic model

1.2 CS traffic model

1.3 PS traffic model


QoS Type

Data integrity should be maintained. Small delay

restriction, requiring correct transmission

Request-response mode, data integrity must be

maintained. High requirements on error tolerance,

low requirements on time delay tolerance

Typically unidirectional services, high

requirements on error tolerance, high

requirements on data rate

It is necessary to maintain the time relationship

between the information entities in the stream.

Small time delay tolerance, requiring data rate

symmetry

Background

download of

EmailBackground

Web page

browse,

network gameInteractive

Non real-tim

e category

Streaming

multimediaStreaming

Voice service,

videophoneConversation

al

Real-tim

e category

For the session-type service, requirement on end-to-end delay is strict. For example, for the voice service, the delay is required to be smaller than 150ms, and must not exceed 400ms, otherwise, it will be difficult to understand the voice. The session-type services are typically carried by the CS domain. For the session-type services, the system can perform no queue processing for the calls. In this case, we can use the Erlang B formula or the extended ErlangB formula to calculate.

Compared with the session-type service, the stream-type service imposes low requirement on the end-to-end delay. Generally, the stream-type service tolerates the call waiting to a greater extent, and can provide the call queue mechanism. In this case, we can use the Erlang C formula to calculate the blocking probability of this type of users (defined as the probability of the call waiting for a specified time).

Interaction-type service refers to the service through which the user requests data from the server. The service is described with the terminal user’s request response pattern. Therefore, round-trip delay is the most important index of this service type. The interaction-type services are typically carried on the CS domain. The background-service tolerates delay to the greatest extent, and can tolerate the delay of a magnitude of an hour. Due to such great delay tolerance, the system can save such requests in the busy hour, and respond when the channel becomes idle; meanwhile, for such services, once a request with higher QoS comes in, the processing can be stopped at any time. The system decides startup and termination at any time, the above formulas—Erlang B formula and Erlang C formula are not applicable. Generally, according to the difference between the maximum number of channels and the busy-hour average occupied channels, we can calculate the traffic of the background-type service. The users of traffic-type services also tolerate the call waiting to some extent. The system provides a queue mechanism, and uses the Erlang C formula to calculate the blocking rate.


Traffic Model

System Configuration

User Behaviour

Service Pattern

Traffic Model Results

By determining the service pattern and the user behaviour parameters, we determine the traffic models of various services in the network. By calculating the hybrid services of multiple traffic models, we determine the network system configuration.


The Contents of Traffic ModelService pattern refers to the service features

User behaviour refers to the conduct of people in using the

service

Service pattern is a means of researching the capacity features of each service type and the QoS expected by the users who are using the service from perspective of data transmission. In the actual application, service pattern is closely related to, and sometimes is no strictly different from, the traffic measurement model.

In the data application, the user behaviour research mainly forecasts the service types available from the 3G, the number of users of each service type, frequency of using the service, and the distribution of users in different regions


Typical Service Features Description

Typical service features include the following feature

parameters:

User type (indoor ,outdoor, vehicle)

User’s average moving speed

Service Type

Uplink and downlink service rates

Spreading factor

Time delay requirements of the service

For each service, since the channel structure and demodulation method are different, the required uplink rate is different from the required downlink rate even for the same service type and the same data rate. For a typical service, we first need to identify whether it is uplink or downlink rate. A typical service can be described by the following parameters:

User type (indoor users, users inside a vehicle, outdoor users)

User’s average moving speed (km/h)

Voice, real-time data, non real time data

Uplink and downlink service rates (kbps)

Spread factor (SF)

Signal delay requirement of the service (ms).

The above parameters ultimately determine the QoS requirements of the service.


CS Traffic ModelVoice service is a typical CS services. Voice data arrival conforms to the Poisson distribution. Its time interval conforms to the exponent distribution

Key parameters of the model

Penetration rate

BHCA: busy-hour call attempts

Mean call duration (s)

Activity factor

Mean rate of service (kbps)

Penetration rate: The percentage of the users that activates this service to all the users registered in the network.

Activity Factor: The weight of the time of service full-rate transmission among the duration of a single session.


CS Traffic Model ParametersMean busy-hour traffic (Erlang) per user = BHCA × mean call duration /3600

Mean busy hour traffic volume per user (kbit) = BHCA × mean call

duration × activity factor × mean rate

Mean busy hour throughput per user (bps) = mean busy hour

traffic volume per user × 1000/3600

(Erl) For CS service, mean busy-hour traffic (Erlang) per user = BHCA * mean call duration /3600 (Erl)

(kbps) Mean busy-hour throughput per user = BHCA * mean call duration * activity factor * mean rate of service*1000/3600 (kbps)


PS Traffic Model

Data Burst Data Burst Data Burst

Packet Call

Session

Packet Call Packet CallDownloading Downloading

Active Dormant Dormant Active

The most frequently used model is the packet service session process model described in ETSI UMTS30.03.


PS Traffic Model Parameters

Traffic Model

Packet Call Num/Session

Packet Num/Packet Call

Packet Size (bytes)

BLER

Typical Bear Rate (kbps)

Reading Time (sec)

The service pattern-related parameters in the traffic model include: these parameters commonly determine the pattern of one session.

We identify the service types through the different values of the parameters.

Packet Call Num/Session: Takes on the geometric random distribution

Reading Time (sec): Takes on the geographic random distribution

Packet Num/Packet Call: Takes on the geographic random distribution

Packet size: Takes on the Pareto random distribution

When using the parameters, the average values will apply.


Parameter DeterminingThe basic parameters in the traffic model are determined in the following ways:

Obtain numerous basic parameter sample data from the existing network

Obtain the probability distribution of the parameters through processing of the sample data

Take the distribution most proximate to the standard probabilityas the corresponding parameter distribution through comparison with the standard distribution function

We have determined the traffic model parameters. The linchpin is to determine such parameter values. The parameter value varies between different services. Pareto General standard probability distributions include: logarithmic normal distribution, Pareto distribution, geometrical distribution, and negative exponent distribution.


PS User Behaviour Parameters

User Behaviour

User Distribution

(High, Medium, Low end)

BHSA

Penetration Rate

The country, region, life custom and economic level will affect the service distribution. In the planning, we divide the users into high-end users, mid-end users and low-end users, and believe that the BHSA and penetration rate are different between different types of user groups. Currently, we can only use the existing analysis to make prediction. In the future, the progress of the construction of the WCDMA pilot system will provide us with reference.


PS User Behaviour ParametersPenetration Rate

BHSA

The times of single-user busy hour sessions of this service

User Distribution (High, Medium, Low end)

The users are divided into high-end, mid-end and low-end

users.

Penetration Rate: The percentage of the users that activate this service to all the users registered in the network. It varies between different service types, user types, and operators. More importantly, it is related to the penetration rate and time. With the elapse of time, the penetration rate will increase gradually.

BHSA: Times of the single-user busy hour sessions of the service. It varies between service types and user types.

User Distribution (High, Medium, Low end): The users are divided into high-end, mid-end and low-end users according to the ARPU. Different operators and different application situations will have different user distributions.


PS Traffic Model ParametersData Transmission time (s): The time in a single session of

service for purpose of transmitting data.

Holding Time (s): Average duration of a single session of service

Activity Factor:

eHoldingTimissionTimeDataTransmctorActivityFa =

eTypicalRatBLERfficVolumeSessionTraissionTimeDataTransm 11

1000/8×

−×

=

issionTimeDataTransmadingTimeRe)1Session

lNumPackketCal(eHoldingTim +×−=

In the PS service, when calculating the data transmission time, the retransmission caused by erroneous blocks should be considered. Suppose the data volume of service source is N, the air interface block error rate is BLER, the total required data volume to be transmitted via the air interface is

NBLER

BLERNBLERNBLERNBLERNN n *1

1**** 32

−=+++++ ΛΛ





4. CE Dimensioning



Basic PrinciplesIn the WCDMA system, all the cells use the same frequency,

which is conducive to improving the WCDMA system

capacity. However, for reason of co-frequency multiplexing,

the system incurs interference between users. This multi-

access interference restricts the capacity in turn.

The radio system capacity is decided by uplink and

downlink. When planning the capacity, we must analyze

from both uplink and downlink perspectives.

Interference is the main factor that decides the system performance of the cellular system. The interference in a cellular system consists of two parts: co-frequency and adjacent frequency interference. All users in the WCDMA system use the same band. All the users are different by modulating the respective signal to the code sequences that are mutually orthogonal. Therefore, the receiving signal is the sum of all user signals and the channel noise.


Contents2. Interference Analysis

2.1 Uplink Interference Analysis

2.2 Downlink Interference Analysis


Uplink Interference AnalysisUplink interference analysis is based on the following

formula:

NotherownTOT PIII ++=

Where:

: Total interference received by NodeB

: Interference from the users of this cell

: Interference from the users of adjacent cells

: Noise floor of the receiver

ownI

otherINP

TOTI


Uplink Interference AnalysisReceiver noise floor: PN

For Huawei NodeB, the typical value is -106.4dBm/3.84MHZ

NFWTKPN += )**log(10

K: Boltzmann constant, 1.38×10-23J/K

T: Temperature in Kelvin, normal temperature: 290 K

W: Signal bandwidth, WCDMA signal bandwidth 3.84MHz

Nth = 10log(K*T*W)=-108dBm/3.84MHz

NF: For Huawei NodeB, typical value is 1.6dB.


Uplink Interference Analysis: Interference from users of this cell

Interference that every user must overcome is :

is the receiving power of the user j , is UL activity factor

Under the ideal power control :

Hence:

The interference from users of this cell is the sum of power of

all the users arriving at the receiver:

ownI

jtotal PI −

jρjP( )

jjjTOT

jNoEb

RW

PIPjAvg

ρ110 10

/ _

⋅⋅−

=

( )jj

NoEb

TOTj

RW

IP

jAvg ρ1

10

1110

/ _⋅⋅+

=

∑=N

jown PI1

Activity Factor: The weight of the time of service full-rate transmission among the duration of a single session. Which is defined by the following formula:

eHoldingTimissionTimeDataTransmorActiveFact =


Uplink Interference Analysis:Interference from users of adjacent cell

The interference from users of adjacent cell is difficult to

analyze theoretically, because it is related to user distribution,

cell layout, and antenna direction diagram.

Adjacent cell interference factor ：

own

other

IIf =

otherI

When the users are distributed evenly

For omni cell, the typical value of adjacent cell interference factor is 0.55

For the 3-sector directional cell, the typical value of adjacent cell interference factor is 0.65


Uplink Interference Analysis

( )( )

N

N

jjNoEb

TOTNotherownTOT P

RW

IfPIII

jAvg

+⋅⋅+

+=++= ∑1

10/

1

10

111

_ ρ

( )jj

NoEb

j

RWL

jAvg ρ1

10

11

1

10/ _

⋅⋅+=

( ) N

N

jTOTTOT PLfII +⋅+⋅= ∑1

1

Define:

Then:

( ) ∑⋅+−⋅= N

j

NTOT

LfPI

1

11

1Obtain:

Where:

N is the number of users in the cell.


Uplink Interference AnalysisSuppose that:

All the users are 12.2 kbps voice users, Eb/NoAvg = 5dB

Voice activity factor = 0.67

Adjacent cell interference factor f=0.55

jρ

Under the above assumption, the threshold capacity is approx 96 users.


Uplink Interference AnalysisAccording to the above mentioned relationship, the noise will rise:

ULN

jN

TOT

LfPINoiseRise

η−=

+−==

∑ 11

)1(1

1

1

The NoiseRise is used in link budget to estimate the Interference Margin

If uplink cell load is 50%, NoiseRise will be 3dB




Uplink Interference AnalysisDefine the uplink load factor for one user:

Define the uplink load factor for the cell:

( ) ( )( )

∑∑⋅⋅+

×+=×+=N

jjEbvsNo

N

jUL

RWfLf

jAvg

1

10

1 1

10

11

111

_ ρ

η

( ) ( )( )

jjEbvsNo

jj

RWfLf

jAvg ρ

η 1

10

11

111

10_

⋅⋅+×+=×+=

When the uplink load factor is 1, is infinite, and the corresponding capacity is called “threshold capacity”.

TOTI


Uplink Interference Analysis LimitationThe above mentioned theoretic analysis uses the following simplifying explicitly or implicitly:

No consideration of the influence of soft handover

No consideration of the influence of AMRC and hybrid service

Ideal power control assumption

Assume that the users are distributed evenly, and the adjacent cell interference is constant

Considering the above factors, the system simulation is a more accurate method:

Static simulation: Monte_Carlo method

Dynamic simulation

No consideration of the influence of soft handover

The users in the soft handover state generates the interference which is slightly less than that generated by ordinary users.

No consideration of the influence of AMRC and hybrid service

AMRC reduces the voice service rate of some users, and makes them generate less interference, and make the system support more users. (But call quality of such users will be deteriorated)

Different services have different data rates and demodulation thresholds. So, we should use the previous methods for analysis, but it will complicate the calculation process.

Since the time-variable feature of the mobile transmission environment, the demodulation threshold even for the same service is time-variable.

Ideal power control assumption

The power control commands of the actual system have certain error codes so that the power control process is not ideal, and reduces the system capacity

Assume that the users are distributed evenly, and the adjacent cell interference is constant


Contents2. Interference Analysis

2.1 Uplink Interference Analysis

2.2 Downlink Interference Analysis


Downlink Interference AnalysisDownlink interference analysis is based on the following

formula:

NotherownTOT PIII ++=

Where:

: Total interference received by UE

: Interference from downlink signal of this cell

: Interference from downlink signal of adjacent cells

: Noise floor of the receiver

ownI

otherINP

TOTI


Downlink Interference AnalysisReceiver noise floor: PN

For commercial UE, the typical value is -101dBm/3.84MHZ

NFWTKPN += )**log(10

K: Boltzmann constant, 1.38×10-23J/K

T: Temperature in Kelvin, normal temperature: 290 K

W: Signal bandwidth, WCDMA signal bandwidth 3.84MHz

Nth = 10log(K*T*W)=-108dBm/3.84MHz

NF: For commercial UE, typical value is 7dB.


Downlink Interference Analysis:Interference from downlink signal of this cell

The downlink users are identified with the mutually orthogonal

OVSF codes. In the static propagation conditions without multi-

path, no mutual interference exists.

In case of multi-path propagation, certain energy will be

detected by the RAKE receiver, and become interference

signals. We define the non-orthogonal factor to describe this

phenomenon:

ownI

TXjown PI ×=α)(

α

Compared to the uplink load equation, the most important new parameter is , which represents the non-orthogonality factor in the downlink. WCDMA employs orthogonal codes in the downlink to separate users, and without any multi-path propagation the orthogonality remains when the base station signal is received by the mobile. However, if there is sufficient delay spread in the radio channel, the mobile will see part of the base station signal as multiple access interference. The orthogonality of 1 corresponds to perfectly orthogonal users. Typically, the non-orthogonality is between 0.1 and 0.6 in multi-path channels.

Where:

PTX is the actual transmission power of NodeB

α


Downlink Interference Analysis

: Interference from the downlink signal of adjacent cell

The transmitting signal of the adjacent cell NodeB will cause

interference to the users in the current cell. Since the

scrambling codes of users are different, such interference is

non-orthogonal

Hence we obtain:

otherI

TXjother PfI ×=)(

Where:

is Adjacent cell interference factor

PTX is the actual transmission power of NodeB

f


Downlink Interference AnalysisEc/Io for User j is:

10/)(10/

10/

10/

10)(1010

)(10)(

NN

PCLTX

j

PCL

TX

CLj

j PfP

Pf

P

IoEc

++×+=

+×+

=αα

Where:

Pj is the transmission power of NodeB for User j

CL is Downlink Coupling Loss, is equals to:

PL_DL: Downlink path lossLf_BS: cable loss of NodeBGa_antenna: Gain of UE antenna and NodeB antennaLb: Body lossSFMNSHO: Slow fading margin without soft handoverLp: Penetration loss

Therefore:

is the useful power received by user j

is the interference from own cell and adjacent cell, and it includes Iown and Iother

is the noise floor of UE

LpSFMLbantennaGaBSLfDLPLCL NSHO +++−+= ___

10/10CLjP

10/max_

10)(

CLTotalDL Pf ××+ ηα

10/10 NP


Downlink Interference AnalysisUnder the ideal power control:

Then we can get:

jjj

NoEb

RW

IoEcj

ρ1)(10 10

)/(

××=

j

TX

PCL

TXj

NoEb

j RWP

fPP

Nj

/

)10(1010/)(

10)/( +

++×××=

αρ

Where:

W is the chip rate, which is 3.84Mcps

Rj is the bit rate of service.

is the activity factor.jρ


Downlink Interference AnalysisDefine the downlink load factor for user j:

Define the downlink load factor for the cell:

maxPPTX

DL =η

j

TX

PCLTX

j

NoEb

jj RW

Pf

PP

PP

Nj

/

)10(1010/)(

max

10)/(

max

+

++×××==

αρη

The downlink load factor are defined in the transmitter side (NodeB).


Downlink Interference AnalysisAccording to the above mentioned relationship, the noise will rise:

( )N

DLMax

N

otherownN

N

total

PCLPfNo

PIIP

PINoiseRise /ηα ××++

=++

==

The NoiseRise is used in link budget to estimate the Interference Margin





4. CE Dimensioning



Capacity Dimensioning FlowDimensioning Start

Assumed Subscribers

CS Peak Cell Load(MDE)

Yes

No

CS Average Cell Load PS Average Cell Load

=Target Cell Load?

Dimensioning End

Total Cell Load

Load per Connection of R99

HSPA Cell Load

}LoadLoadLoad,Loadmax{Load HSUPAavgPSavgCSpeakCSUL_totalcell ++= −−−−

CCHHSDPAavgPSavgCSpeakCSDL_totalcell Load}LoadLoadLoad,Loadmax{Load +++= −−−−

For UL, the load per connection of R99 is calculated by the following formula:

For DL, the load per connection of R99 is calculated by the following formula:

Typical Value: ( for AMR 12.2k is 0.67, is 0.65, is 50%, is 75%, load of CCH is 20%, Channel model is TU3, DL CL is 135dB, is 0.5, NodeB max transmission power is 43dBm)

( ) ( )( )

jjEbvsNo

jj

RWfLf

jAvg ρ

η 1

10

11

111

10_

⋅⋅+×+=×+=

j

TX

PCLTX

j

NoEb

ii RW

Pf

PP

PP

Nj

/

)10(1010/)(

max

10)/(

max

+

++×××==

αρη

19.59%21.35%PS384k

8.03%8.69%PS128k

4.11%4.77%PS64k

5.81%4.99%CS64k

1.05%1.19%AMR12.2k

DownlinkUplinkLoad per User

jρ f ULη ULηα


Contents3. Capacity Dimensioning

3.1 R99 Capacity Dimensioning

3.2 HSDPA Dimensioning


Capacity Dimensioning Differences

GSM

Hard blocking

Capacity --- hardware dependent

Single service

Single GoS requirement

Capacity dimensioning ---ErlangB

WCDMA

Soft blocking

Capacity --- interference dependent

Multi services (CS&PS)

Respective quality requirements of

each service

Capacity dimensioning ---

Multidimensional ErlangB

The GSM capacity is decided by the number of carriers, it is hard capacity. But WCDMA capacity is related to interference, coverage, channel condition, it is soft capacity.

The Erlang-B formula is only used for

Circuit switched services

Single service

Multidimensional ErlangB (MDE) is suitable for:

Multi service with different GoS

Different service will share the same resource.


Multidimensional ElangB Principle (1)

Multidimensional ErlangB model is a Stochastic Knapsack Problem.

“Knapsack” means a system with fixed capacity, various objects arrive at

the knapsack randomly and the states of multi-objects in the knapsack

are stochastic process.

Then when various objects attempt to access in this system, how much is

the blocking probability of every object?

K classes of services

Blockedcalls

Callsarrival

Callscompletion

Fixed capaciy

Multidimensional ErlangB is a public algorithm. Now Huawei selects it. Operators can use different algorithm to calculate the load.


Multidimensional ElangB Principle (2)

Case Study: Two dimensional ErlangB Model

The size of service 2 is twice as that of service 1

C is the fixed capacity

n2

Blocking States of Class 1

C

C-b1

n1

n2

Blocking States of Class 2

C

C-b2

n11 2 3 4 5 6

1

2

3

1 2 3 4 5 6

1

2

3

n2

States Space

C

n11 2 3 4 5 6

1

2

3

Ω

b1:size of service 1, which means the resource required by service 1 .

b2:size of service 2, which means the resource required by service 2 .

b2=2*b1

n1: number of service 1 connection

n2: number of service 2 connection

The left graph describes all the states (blue dots) that satisfies: n1*b1+n2*b2<=C

The red dots in the central graph describe the blocking states for service 1, that means in these red states, service 1 cannot access the network.

The red dots in the central graph describe the blocking states for service 1, that means in these red states, service 1 cannot access the network.


CS Capacity Dimensioning (1)CS services

Real time

GoS requirements

Multidimensional ErlangB

Resource sharing

Meeting GoS requirements

Capacity

Blocking probability Cell Loading

?MDE

Channels......

AMR12.2k

CS64k

Multidimensional ErlangB Model

MDE is used to calculate the peak load.


CS Capacity Dimensioning (2)Comparison between ErlangB and Multidimensional

ErlangB

Multidimensional ErlangB - Resources shared

High Utilization of resources

ErlangB - Partitioning Resources

Low Utilization of resources

ErlangB allocate the resource according to the peak load of each service. Different service are separate, they cannot share the resource.

MDE considers the probability that different service reach the peak load at the same time is very low, then the services can share the same resource, and decrease the resource requirement.

If there is only one service, MDE is the same with ErlangB.


Best Effort for Packet ServicesPS Services:

Best Effort

Retransmission

Burst Traffic

PS will use the spare load apart from that used by CS

Total Load

CS Peak Load

CS Average Load

Load occupied by CS

Load occupied by PS

Load

Time

Best effort means that the packet service can utilize the resource that is available. PS service can be considered as BE service.

Retransmission of PS = BLER/(1-BLER)

PS traffic burst is a method to ensure the QoS, it is obtained from simulation based on time delay requirement.


Capacity DimensioningAverage load:

Peak load:

Query the peak connection through ErlangB table

jjj LoadFactorTrafficdAverageLoa ×=

∑=N

jTotal dAverageLoadAverageLoa1

jjj LoadFactorPeakConnPeakLoad ×=

)( jTotal PeakLoadMDEPeakLoad =

Where:

AverageLoadj is the average load for service j

For the total average load, the result is the sum of AverageLoad for different service

PeakLoadj is the peak load for service j

For the total peak load, we should calculate it by MDE. The result is lower than the sum of PeakLoad for different service, Because it


Case Study (1)Common parameters:

Maximum NodeB transmission power: 20W

Subscriber number per Cell: 800

Overhead of SHO (including softer handover): 40%

Retransmission of PS is 5%

R99 PS traffic burst: 20%

Activity factor of PS is 0.9

Power allocation for CCH is 20% in downlink


Case Study (2)Traffic Model, GoS and load factors:

4.21%

4.99%

1.18%

Load Factors (UL)

0

0

50

0.001

0.02

UL

N/A0PS384 (Kbit)

5.94%N/A100PS128k (Kbit)

2.96%N/A100PS64k (Kbit)

4.65%2%0.001CS64k (Erl)

0.83%2%0.02AMR12.2k (Erl)

Load Factors (DL)GoS DL


Case Study (2)Uplink Average Load Downlink Average Load

AMR12.2k:

0.02*800*1.18%=18.88%

CS64k:

0.001*800*4.99%=3.99%

PS64k:

50*800*(1+5%)*(1+20%)/0.9/64/360

0*4.21%=1.02%

CS&PS uplink average load:

18.88%+3.99%+1.02%=23.89%

AMR12.2k:

0.02*800*(1+40%)*0.83%=18.59%

CS64k:

0.001*800 *(1+40%)* 4.65%=5.2%

PS64k:

100*800*(1+5%)*(1+40%)*(1+20%)/0.9/64/3600*2.96%=2.01%

PS128k: 2.02%

CS&PS downlink average load:

18.59%+5.2%+2.01%+2.02%=27.82%

The difference between UL and DL is: DL should consider the soft handover, but UL doesn’t need.


Case Study (3)Uplink Peak Load Downlink Peak Load

AMR12.2k:

Traffic=0.02*800=16Erl

Peak Conn= ErlangB(16, 2%)=24

Peak Load=24*1.18%=28.32%

CS64k:

Traffic=0.001*800=0.8Erl

Peak Conn= ErlangB(0.8, 2%)=4

Peak Load=4*4.99%=19.96%

CS Peak Load: 42.53%

AMR12.2k:

Traffic=0.02*800*(1+40%)=22.4Erl


Peak Load=31*0.83%=25.73%

CS64k:

Traffic=0.001*800 *(1+40%)=1.12Erl


Peak Load=5*4.65%=23.25%



Contents3. Capacity Dimensioning

3.1 R99 Capacity Dimensioning

3.2 HSDPA Dimensioning


HSDPA Capacity Dimensioning (1)HSDPA Capacity Dimensioning

The purpose is to obtain the required HSDPA power to satisfy

the cell average throughput.

HS-DSCH will use the spare power apart from that of R99

Dedicated channels (power controlled)

Common channels

Power usage with dedicated channels channels

t

Unused power

Power

HS-DSCH with dynamic power allocationt

Dedicated channels (power controlled)

Common channels

HS-DSCH

Power3GPP Release 99 3GPP Release 5

Pmax-R99

HSDPA Capacity Dimensioning

to obtain the average cell throughput

based on HSDPA simulation result

considering the gain of HSDPA scheduling

the maximum data rate is limited by the available power, available codes resource and UE capacity

higher cell target load can be available for HSDPA


HSDPA Capacity Dimensioning (2)Capacity Based on Simulation

to simulate Ior/Ioc distribution in the

network with certain cell range

to simulate cell throughput distribution

based on Ec/Io distribution in the cell

Dimensioning Procedure

0.00%

0.50%

1.00%

1.50%

2.00%

2.50%

3.00%

3.50%

4.00%

4.2

2

2.9

8

2.0

4

1.3

9

0.9

6

0.6

6

0.4

5

0.3

1

0.2

1

0.1

4

0.1

0.0

7

0.0

5

0.0

3

0.0

2

0.0

1

0.0

1

0.0

1 0 0 0 0

Ioc/Ior

Dist

ribut

ion

prob

abil

ity

DU Cell coverage Radius=300m

Conditions of SimulationChannel model-TU35 codes

Simulation

Ec/Io distribution

Ior/Ioc distribution

Cell coverageradius

Cell averagethroughputEc/Io =>throughput

HSDPA PowerAllocation

During the HSDPA capacity dimensioning procedure, we know the Cell Coverage Radius (obtained from the coverage planning) and Cell Average Throughput(obtained from the traffic model), and we want to get the HSDPA Power Allocationbased on simulation.


Case StudyInput parameters

Subscriber number per cell: 800

HSDPA Traffic model: 1200kbit per subs

HSDPA Retransmission rate: 10%

The power for HS-SCCH: 5%

Cell radius: 1km

HSDPA cell average throughput:

The needed power for HS-DSCH including that for HS-SCCH is 18.38%

kbps293%)01(1*3600

1200*800=+


Case StudyUplink Total Load of the Cell :


CS&PS average load: 23.89%

Downlink Total Load of the Cell :


CS&PS average load: 27.82%

HSDPA load is 18.38%

CCH load: 20%

66.20%%. MAXLoadLoadLoadLoadLoadLoad CCHHSDPAavgPSavgCSpeakCSDLtotalcell

=++=

+++= −−−−

%20%)38.188227%,33.42(},max{_

%4%. MAXLoadLoadLoadLoad avgPSavgCSpeakCSULtotalcell

53.2)8923%,53.42(},max{_

==

+= −−−−

Base on this capacity dimensioning result, we can check whether the cell load of the network is beyond the network target. If it is, we should adjust the cell radius.





4. CE Dimensioning



OverviewDefinition of a CE:

A Channel Element is the base band resource required in the Node-B

to provide capacity for one voice channel, including control plane

signaling, compressed mode, transmit diversity and softer handover.

NodeB Channel Element Capacity

One BBU3900

UL 1,536 CEs with full configuration

DL 1,536 CEs with full configuration

Due the technical features of the WCDMA, compared with the 2G systems such as GSM, the RNC and Node B present enormous capacity. For example, for the fully configured NodeB, the number of channels of one carrier is 128, which is more than 10 times of that supported by a TRX of GSM. One uplink processing unit of our NODEB has the processing capacity of 128 12.2kbps voice channels. One 3*1 WCDMA BTS is equivalent to the GSM sites of one S10/10/10. At the beginning of the WCDMA network construction, so high a capacity is not a necessity, and only a portion of it is required (e.g., 10%). If we offer the quotation based on the maximum hardware channel capacity of TRX like the GSM, it will make the operators incur enormous cost and mismatch the user quantity. To reduce the initial investment, the operator is bound to pay the equipment price to the supplier according to the actual use capacity, and, subsequently, pay more equipment prices with the increase of the user quantity. This way, the operator will reduce the initial investment and mitigate the risks.


Huawei Channel Elements Features

Channel Elements pooled in one NodeB

No need extra R99 CE resource for CCH

reserved CE resource for CCH

No need extra CE resource for TX diversity

No need extra CE resource for Compressed Mode

reserved resources for Compressed Mode

No need extra CE resource for Softer HO

HSDPA does not occupy R99 CE resource

separate module for HSDPA

HSUPA shares CE resource with R99 services

No additional CE resource for AGCH RGCH and HICH

Softer HO CE: 3900 series NodeB doesn’t need extra CE resource, but 3800 series NodeB needs extra CE resource

HSUPA shares CE resource with R99 services: that means the HSUPA E-DCH shares CE resource with R99 services


CE Dimensioning Flow

),( _______ HSUPAULAULPSULAverageCSULPeakCSTotalUL CECECECECEMaxCE +++=

),( _______ DLADLPSDLAverageCSDLPeakCSTotalDL CECECECEMaxCE ++=

Dimensioning Start

CS Average CE

Channel Elements per NodeB

Dimensioning End

--Subscribers per NodeB--Traffic model

PS Average CECS Peak CE (MDE) HSPA CE


CE Mappings for R99 Bearers

8 10 PS384k

4 5 PS144k

4 5 PS128k

2 3 PS64k

2 3 CS64k

1 1 AMR12.2k

DownlinkUplinkBearer

Channel Elements Mapping for R99 Bearers

The mapping relationship of Channel Elements consumption for each bearer is based on Uplink 2-way diversity

In the case of uplink 4-way diversity, the CE consumption is shown below:

Bearers CE (4-way diversity)

AMR12.2k 2

CS64k 4

PS64k 4

PS128k 8

PS384k 16

Detailed and recently updated data should be referred to the newest issued notice of "UMTS RAN Product Specificaiton".


R99 CE Dimensioning PrinciplePeak CE occupied by CS can be obtained through multidimensional

ErlangB algorithm

Average CE needed by CS and PS depend on the traffic of each service,

i.e.

Average CE = Traffic * CE Factor

CEResources...

...

AMR12.2k

CS64k

Multdimensional ErlangB Model

Total CE

CS Peak CE

CS Average CE

CE occupied by CS

CE occupied by PSand HSPA

CE

Time

CE resource shared among each service

The CE dimensioning principle is similar with capacity dimensioning.


HSDPA CE DimensioningIn uplink, no CE consumption for HS-DPCCH if corresponding UL

DCH channel exists

In uplink, CE consumed by one A-DCH depends on its bearing

rate

In downlink, A-DCH is treated as R99 DCH.

No additional CE needed for HS-DSCH and HS-SCCH

One HSDPA link need one A-DCH in uplink and

downlink respectively

HS-DSCHHS-SCCHHS-DPCCH

Associated Dedicated Channels

Site 1 Site 2

HSDPA channels doesn’t occupy R99 CE resource, but we should calculate the A-DCH CE.


CE Mappings for HSDPA Bearers

1 CE---DL A-DCH (DPCCH)---3 CEUL A-DCH (DPCCH)---0 CEHS-DPCCH

0 CE---HSDPA TrafficDownlinkUplinkTraffic

HSDPA Channel Elements Consumption

HSDPA Traffic:

Separate dedicated module processing HSDPA Traffic so HSDPA traffic does not occupy any R99 CE resource.

HS-DSCH and HS-SCCH does not affect base band capacity for R99 services.

HS-DPCCH

HS-DPCCH doesnot consume any R99 Channel Element since its base band resource is reserved in BBU module.

UL A-DCH (DPCCH)

PS64k is recommended to bear uplink user data, TCP acknowledgement and signaling.

One PS64k consumes 3 CE in uplink.

DL A-DCH (DPCCH)

A-DCH bears DL signaling control.

A-DCH can be beared on HSDPA since RAN10.0.


Case Study (1)Input Parameters

Subscribers number per NodeB: 2000

Overhead of SHO: 30%

R99 PS traffic burst: 20%

Retransmission rate of R99 PS: 5%

PS Channel element utilization rate: 0.7

Average throughput requirement per user of HSDPA: 400kbps

HSDPA traffic burst is 25%

Retransmission rate of HSDPA is 10%

00

500.0010.02

UL

N/A1200HSPA (kbit)N/A80PS128k (kbit)N/A100PS64k (kbit)2%0.001CS64k (Erl)2%0.02AMR12.2k (Erl)

GoS DLTraffic Model

In this case, the R99 traffic model includes the traffic of HSDPA UL A-DCH. That means 50kbits for UL PS64k includes the R99 UL DCH and HSDPA UL A-DCH.


Case Study (2)Uplink CE Dimensioning Downlink CE Dimensioning

AMR12.2:Traffic =0.02*2000*(1+30%) = 52Erl Peak CE =ErlangB(52,0.02)*1= 63 CEAverage CE =52*1=52 CECS64:Traffic =0.001*2000*(1+30%) = 2.6Erl Peak CE =ErlangB(2.6,0.02)*3 = 21 CEAverage CE =2.6*3=9 CETotal peak CE for CS: 80CETotal average CE for CS: 52+9=61CE

AMR12.2:Traffic =0.02*2000*(1+30%) = 52Erl Peak CE =ErlangB(52,0.02)*1 = 63CEAverage CE =52*1=52CETraffic of VP:Traffic =0.001*2000*(1+30%) = 2.6Erl Peak CE =ErlangB(2.6,0.02)*2 =14CEAverage CE =2.6*2=6CETotal peak CE for CS: 74CE Total average CE for CS: 52+6=58CE

Different with capacity dimensioning, the UL CE dimensioning should consider the soft handover.

For the peak CE, we should use MDE to calculate.


Uplink CE Dimensioning Downlink CE Dimensioning

CE for PS64k:

Total CE for R99 PS services:4CE

4CE5%)(1*20%)(1*30%)(1*3*3600*0.7*6450*2000

=+++

CE for PS64k:

CE for PS128k:

Total CE for R99 PS services:

4+4=8CE

CE for HSDPA A-DCH:

3CE10%)(1*%)52(1*1*3600*4001200*2000

=++

4CE5%)(1*20%)(1*30%)(1*2*3600*0.7*64

100*2000=+++

4CE5%)(1*20%)(1*30%)(1*4*3600*0.7*12880*2000

=+++

Case Study (3)

In this case, the R99 traffic model includes the traffic of HSDPA UL A-DCH, therefore it is no need to calculate the HSDPA UL CE

For the HSDPA DL A-DCH CE, strictly speaking, it can perform soft handover. But usually the CE requirement is low, so in Huawei strategy, the soft handover is not considered.


Case Study (4)Uplink CE Dimensioning Downlink CE Dimensioning

Total CE Total CE

CE MAX

CECE

CEMaxCE

ULAveragePSULAverageCS

ULPeakCSTotalUL

80)461,80(

)

,(

____

___

=+=

+

=

CE 743)858 Max(74,

)CECECE

,CE(MaxCE

DL_ADL_PSDL_Average_CS

DL_Peak_CSTotal_DL

=++=

++

=





4. CE Dimensioning



Network Dimensioning Flow

UL/DL Link Budget

Cell Radius=Min (RUL, RDL)

UL/DL CapacityDimensioning

Satisfy Capacity Requirement?

Capacity Requirement

Adjust Carrier/NodeBNo

Yes

CE Dimensioning

Output NodeB Amount/NodeB Configuration

Coverage Requirement

start

End

WCDMA RAN Planning and Optimization (Book2 Design and Planning)

Documents

Transcript of WCDMA RAN Planning and Optimization (Book2 Design and Planning)