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4 WCDMA Radio Coverage

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WCDMA Radio Network Design

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OBJECTIVES:

On completion of this chapter the student will be able to:

Explain free space path loss.

Use Okumura-Hata and COST 231-Walfish-Ikegami propagation formulas.

Explain the concept of log normal fading and how it is incorporated in WCDMAcoverage calculations.

Calculate the sensitivity of a RBS for various services,

Perform link budget calculations for the uplink of a WCDMA system.

Use simulation graphs to calculate the downlink coverage and capacity of aWCDMA cell.

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Contents

RADIO WAVE PROPAGATION........................................................... 86

OKUMURA-HATA PROPAGATION FORMULA............................................ 89

COST 231-WALFISH-IKEGAMI PROPAGATION FORMULA ....................... 89

SIGNAL VARIATIONS ..................................................................................90

POWER CONTROL MARGIN (PCMARG) ........................................................ 95

BODY LOSS (BL)..........................................................................................96

CAR PENETRATION LOSS (CPL)................................................................96

ANTENNA SYSTEM CONTROLLER (ASC) INSERTION LOSS (LASE) .........96

FEEDER AND JUMPER LOSSES (LF+J) ....................................................... 97

RBS SENSITIVITY (RBSSENS) ....................................................................... 98

UPLINK LOAD ............................................................................................ 102

LINK BUDGET CALCULATION FOR UPLINK................................. 103

MAXIMUM PATH LOSS (LPATHMAX).............................................................. 104

WCDMA CELL RANGE............................................................................... 106SITE COVERAGE AREA ............................................................................ 107

DOWNLINK DIMENSIONING ........................................................... 109

DOWNLINK LINK BUDGET ........................................................................ 110

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RADIO WAVE PROPAGATION

In this course, we are primarily interested in the transmission lossbetween two antennas: the transmitter/emitter and the receiver.Many factors, including absorption, refraction, reflection,diffraction, and scattering affect the wave propagation. However, infree space an electromagnetic wave travels indefinitely ifunimpeded. This does not mean there are no transmission losses,as we will see in this first simple model where isotropic emission

from the transmitter and line of sight between the two antennasseparated by a distance, d, in free space are assumed (Figure4-1).

d

Figure 4-1 Free space path loss

Since an isotropic antenna, by definition, distributes the emittedpower, Pt, equally in all directions, the power density, Sr, (powerper area unit) decreases as the irradiated area, 4d2, at distanced, increases, that is:

SP

dr

t=4

2

If the transmitting antenna has a gain, Gt, it means that it isconcentrating the radiation towards the receiver. The powerdensity at the receiving antenna increases with a factorproportional to Gt, that is:

SP G

dr

t t=4

2

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The power received by the receiving antenna, Pr, is proportional to

the effective area, Ar, of that antenna, that is:

P S Ar r r

=

It can be shown that the effective area of an antenna isproportional to the antenna gain, Gr, and the square of the

wavelength, , of the radio wave involved, that is:

AG

r

r=

2

4

and, hence, the received power becomes

( )P

P G G

dr

t t r=

2

24

The transmission loss can be calculated as the ratio between thetransmitted power and received power, that is:

( )loss

P

P

d

G G

t

r t r

= = 4

2

2

Radio engineers work with the logarithmic unit dB so thetransmission loss, L, then becomes

( ) ( )

( ) ( )L lossd

G G

dG G

t r

r t= =

=

10 10

420

410 10

2

2log log log log log

Radio engineers treat the antenna gains, 10log(Gr) and 10log (Gt),separately, so that what is given in the literature as the path loss,

Lp, is only the term 20log(4d/).In clearer terms, the path loss infree space is given by equation 14 below.

Free Space Path lossLd

p=

204

log

Equation 14 Free space path loss

Note that the wavelength dependency of the path loss does notcorrespond to losses in free space as such. It is a consequence ofthe finite effective receiver area.

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This transmission loss expression is fairly general. The only thing

which changes when we improve our models is the expression forthe path loss. The antenna gain is normally given in dB(i), that is,as 10log(G), where gain means a reduction of the totaltransmission loss, L, between a transmitting and receivingantenna.

This model helps us to understand the most important features ofradio wave propagation. That is, the received power decreaseswhen the distance between the antennas increases and thetransmission loss increases when the wavelength decreases (oralternatively when the frequency increases).

For cell planning, it is very important to be able to estimate thesignal strengths in all parts of the area to be covered, that is, topredict the path loss.The model, described in this section, can beused as a first approximation. However, more complicated modelsexist. Improvements can be made by accounting for:

The fact that radio waves are reflected towards the earths surface. Transmission losses, due to obstructions in the line of sight. The finite radius of the curvature of the earth. The topographical variations in a real case, as well as the different

attenuation properties of different terrain types, such as forests,urban areas, etc.

The best models used are semi-empirical, that is, based onmeasurements of path loss/attenuation in various terrain. The useof such models is motivated by the fact that radio propagationcannot be measured everywhere. However, if measurements aretaken in typical environments, the parameters of the model can befine-tuned so that the model is as good as possible for thatparticular type of terrain.

Two common propagation formulas are Okumura-Hata (equation

15) and COST 231- Walfish-Ikegami (equation 16)

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OKUMURA-HATA PROPAGATION FORMULA

Lpath = A - 13.82logHb+(44.9-6.55logHb)logR - a(Hm) [dB]

Equation 15 Okumura-Hata Propagation formula

where

A = 155.1 for urban, A = 147.9 for suburban and semi-open areas

A = 135.8 for rural, A = 125.4 for open areas.

Hb= base station antenna height [m]

Hm= UE antenna height [m]

R = distance from transmitter [km]

a(Hm) = 3.2(Log(11.75*Hm))2- 4.97 or for 1.5m antenna a(1.5) = 0

COST 231-WALFISH-IKEGAMI PROPAGATION FORMULA

Lpath = 155.3 + 38logR 18log(Hb 17) [dB]

Equation 16 COST 231-Walfish-Ikegami propagation formula

where



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SIGNAL VARIATIONS

The models, described in the previous section, can be used toestimate the average signal level (called the global mean) at thereceiving antenna. However, a radio signal envelope is composedof a fast fading signal super-imposed on a slow fading signal asshown in Figure 4-2 below.

SS at Rx-antenna

DistanceVariations due to Shadowing (Local mean)

Received Signal Level from formulae (Global mean)

Variations due to

Rayleigh fading

Figure 4-2 Signal Variations

These fading signals are the result of obstructions and reflections.They yield a signal, which is the sum of a possibly weak, direct,line-of-sight signal, and several indirect, or reflected signals.

The short term or fast fading (Rayleigh fading) signal (peak-to-peak distance /2) is usually present during radiocommunication, due to the fact that the mobile antenna is lowerthan the surrounding structures, such as trees and buildings.These act as reflectors. The resulting signal consists of severalwaves with various amplitudes and phases. Sometimes thesealmost completely cancel out each other. This can lead to a signallevel below the receiver sensitivity. In open fields where a directwave is dominating, this type of fading is less noticeable.

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The first and most simple solution is to use more power at the

transmitter(s), thus providing a fading margin. Another way toreduce the harm done by Rayleigh fading is to use space diversity,which reduces the number of deep fading dips. Diversity meansthat two signals are received which have slightly differenthistoriesand, therefore, the bestcan be used, or even better:the two can be combined.

The signal variation received, if we smooth out the short-termfading, is called the local meanand its power, often called thelocal average power. The measured mean value is log normallydistributed about the derived value with a standard deviation asshown in Figure 4-3 below.

SS at RX antenna

Probability

Derived Mean

Standard Deviation( )

Measured Mean

Figure 4-3 Log Normal Fading

Therefore, this slow fading is called log-normal fading. If we drive

through a flat desert without any obstructions, the signal variesslowly with distance. However, in normal cases the signal path isobstructed.

Obstructions near the mobile (for example, buildings, bridges, andtrees) cause a rapid change in the local mean (in the range of fiveto fifty meters), whereas topographical obstructions cause a slowersignal variation (shadowing). Because log-normal fading reducesthe average strength received, the total coverage from thetransmitter is reduced. To combat this, a fading margin must beused.

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If outdoor base stations are used to provide indoor coverage

building penetration loss must be take into consideration.

Building penetration loss is defined as the difference between theaverage signal strength immediately outside the building and theaverage signal strength over the ground floor of the building.Typical values of the mean building penetration loss, BPL,aregiven in Table 4-1 below.

Environment BPL[dB] LNF(o)[dB] LNF(i)[dB] LNF(o+i) [dB]

Dense urban 18 10 9 14

Urban 18 8 9 12

Suburban 12 6 8 10

Table 4-1 Building penetration loss

The building penetration loss for different buildings is also log-

normally distributed with a standard deviation of BP. Variations ofthe loss over the ground floor could be described by a stochasticvariable, which is log-normally distributed with a zero mean value

and a standard deviation of floor.

Here

BPLand

floorare lumped together by adding the two as ifthey were standard deviations in two independent log-normally

distributed processes. The resulting standard deviation, indooror

LNF(i), could be calculated as the square root of the sum of the

squares. Typical values of LNF(i) are presented in Table 4-1.

The total log-normal fading is composed of both the outdoor log-

normal fading,LNF(o),and the indoor log-normal fading LNF(i). Thetotal standard deviation of the log-normal fading is given by thesquare sum:

2

)(

2

)()( iLNFoLNFioLNF

+=+

Values of LNF(o+i) are presented in Table 4-1. These are thevalues that should be used in the link budgets when calculating theLNFmarg, required to achieve a certain probability of indoorcoverage.

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This combining of standard deviations is illustrated in Figure 4-4

below.

Ground floor

indoor orLNF(i)

floorBPLLNF(o)

LNF(o+i) = LNF(o)2

+LNF(i)2

Figure 4-4 Log-normal fading margins for indoor coverage

Note that the characteristics of different urban, suburban etc.environments can differ significantly throughout the world. Thusthe values in Table 4-1 must be treated with care. They should beconsidered as a reasonable approximation when no otherinformation is obtainable. Rural areas are not considered in Table4-1 since indoor coverage is not usually calculated for them.

Once the standard deviation has been established the requiredLNF margin is determined from the required probability ofcoverage.

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In Figure 4-5 below it can be seen that a LNF margin of 4.1dBwould be required to produce a 95 % probability of coverage if allusers were outdoor in an urban environment. This increases to7.5 dB if the same probability of coverage is required indoors.

LNF=7.5 dB

Environment BPL[dB] LNF(o)[dB] LNF(i) [dB] LNF(o+i) [dB]

Dense urban 18 10 9 14

Urban 18 8 9 12

Suburban 12 6 8 10

Outdoor Urban

Indoor Urban95%probability of

coverage

LNF=4.1 dB

Figure 4-5 LNF margins for urban environment

A complete set of LNF margins for 3 sector sites is shown in

Table 4-2 below.

Table 4-2 LNFmargfor 3 sector sites

The log-normal fading margins presented above reflect the casewhere the UE can make a handover to other cells whenexperiencing poor coverage. If handover is allowed, the log-normalfading margins can be reduced as compared to the single cellcase. This reduction is referred to as handover gain and isincluded in the values for log-normal fading margins.

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POWER CONTROL MARGIN (PCMARG)

In a WCDMA system fast power control (1500 Hz) is employed.For slowly moving UEs the power control has the ability tocompensate for the fast fading, thus reducing the Eb/No. However,due to the characteristics of the fast fading, more power will berequired in the fading dips than the corresponding reduction in thefading tops. The result is that each UE (BS) has to increase itsaverage power in order to combat fast fading. This effect is calledTX increase. A sensitivity degradation for UEs located at cellborders also appears, since the UE power control at cell bordersno longer can fully compensate for fading dips.

To cater for the combined effect of TX increase and the sensitivitydegradation at cell borders a power control margin PCmargoftypically 2 dB is used in the link budget. Note that this value ischannel-model dependent. PCmargfor the various channel modelsis shown in Table 4-3 below.

Table 4-3 Power Control Margin (PCmarg)

The following losses must be considered for coveragecalculations:

Body Loss (BL)

Car Penetration Loss (CPL)

Building Penetration Loss(BPL)

Feeder and Jumper losses (LF+J)

If an Antenna System Controller (ASC) is fitted at the base station,losses associated with the antenna feeder and jumper cables(LF+J) will be overcome for the uplink. But they must be included indownlink calculations along with the insertion loss of the ASC(LASC).

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BODY LOSS (BL)

The human body has several negative effects on the UEperformance. For example, the head absorbs energy, and theantenna efficiency of some UEs can be reduced. To cater forthese effects a margin for body loss has to be included in the linkbudget. The body loss margin recommended by ETSI is 3 dB for1900 MHz.

Generally, body loss is not applied to data services since the userswill most likely not have the terminal at their ear.

CAR PENETRATION LOSS (CPL)

When a UE is placed in a car without an external antenna, anextra margin has to be added in order to cope with the penetrationloss to reach inside the car. This extra margin is approximately 6dB.

The recommended values for body and car losses are shown inTable 4-4 below.

Table 4-4 Body and Car penetration losses

ANTENNA SYSTEM CONTROLLER (ASC) INSERTION LOSS (LASE)

The ASC will add a propagation loss to the RBS downlink.

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FEEDER AND JUMPER LOSSES (LF+J)

Feeder and jumper losses is the combined loss associated withthe feeder and jumper cable, as below:

Lf+J = Feeder attenuation + jumper attenuation

Typical feeder attenuations are shown in Table 4-5 below.

Table 4-5 Typical Feeder Attenuation

The jumper loss can vary depending on the length but typicalvalues are in the order of 1dB.

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RBS SENSITIVITY (RBSSENS)

The sensitivity of the RBS is the minimum signal level it needs toreceive to decode the channel.

It is the C/I for the service () added to the thermal noise (N) andthe noise figure of the receiver (noise introduced by the RBS) asshown below:

Minimum RX signal (RBSsens)= Noise + Nf+

In other words RBSsensis C/I dB above (Noise+Nf)as illustrated inFigure 4-6 below.

RBSsens

C/I

Noise +Nf

Figure 4-6 RBS Sensitivity

The level of noise for a particular bandwidth and temperature canbe calculated using the formula below.

Noise = KTB W/Hz

K is Boltzmanns constant = 1.38 X 10-23J/K

T is the absolute temperature in Kelvin = 290 (17oC)

B is the bandwidth over which the noise is measured.

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If these are expressed as log values:

Noise = KT + 10log(B) = Thermal noise (Nt) + 10 log (B)

Therefore:

RBSsens= Nt+ 10log(B) + Nf+

However Eb/No = + 10 log (B/Rinfo)

= + 10 log (B) - 10 log (Rinfo)

To solve for

=> = Eb/No - 10 log (B) + 10 log (Rinfo)

If is substituted into the equation for RBSsensit becomes: -

RBSsens= Nt+ 10log(B) + Nf+ Eb/No - 10 log (B) + 10 log (Rinfo)

The negative 10 log (B) will cancel out the positive one leavingequation 17 below.

RBSsens= Nt+ Nf+ 10 log (Rinfo) +Eb/NodBm E

Equation 17 RBS Sensitivity equation

where

Ntis the thermal noise power density = -174 dBm/Hz

Nfis the noise figure = 3 dB with ASC, 4 dB without ASC

Ruseris the total RAB bit rate in bps, i.e. user rate + 3.4 kbps

signaling

Eb/Nois the energy per bit to noise ratio for the service.

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RBS Sensitivity Examples

What is the sensitivity of an RBS with ASC for the services shownin Table 4-6 below?

Speech RBS sensitivity in dBm

64 kbps PS RBS sensitivity in dBm

Table 4-6 Example RBS Sensitivities

Nt= 10 log (KT) dBW/Hz

K= Boltzmans constant 1.38 x 10-23 J/K

T = Standard noise temperature = 290oK

=> Nt = 10 log (KT/10-3) dBm/Hz

= 10 log(1.38 x 10-23 X 290/10-3)

= -174 dBm/Hz

RBSsens= Nt+ Nf+ 10 log (Rinfo) +Eb/NodBm

= -174 + 3 + 10log (Rinfo) +Eb/NodBm

= -171 + 10log (Rinfo) +Eb/NodBm

For speech

Rinfo= 12.2 kbps + 3.4 kbps = 15.6 kbps = 15600 bps

RBSsens= -171 + 10log (15600) +Eb/NodBm

= -171 + 41.9 +Eb/No

= -129.1 +Eb/No

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When Eb/No =4.9 dB

RBSsens= -129.1 + 4.9 = -124.2 dBm

When Eb/No =6.4 dB

RBSsens= -129.1 + 6.4 = . dBm

For 64kbps PS

Rinfo= 64 kbps + 3.4 kbps = .kbps = .. bps

RBSsens= -171 + 10log (..) +Eb/NodBm

= -171 + . +Eb/No

= .. +Eb/No

When Eb/No =3.2 dB

RBSsens= . + 3.2 = .... dBm

When Eb/No =4.5 dB

RBSsens= .+ 4.5 = . dBm

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UPLINK LOAD

As users are connected to the cell the overall uplink noise will rise.This means that the sensitivity of the RBS will increase with alsoincrease. As shown in Figure 4-7 below the sensitivity of a loadedRBS is the unloaded sensitivity plus the uplink noise rise (IUL)

C/I

Nt+ 10log (Bw) + Nf

RBSsens

(unloaded) = Nt

+ 10log (Bw) + Nf

+C/I

Noise rise (Iul)

RBSsens(loaded) = RBSsens(unloaded) + IUlNoise rise (Iul)

Figure 4-7 Sensitivity of loaded RBS

Uplink noise rise can be derived from equation 18 below.

IUL = 10log1

1 - QdB

Equation 18 Uplink Noise Rise (IUL)

Where Qis the Uplink load in the cell (0 to 1)

Uplink Load Example

How much will the uplink noise rise when a cell is becomes 50%loaded?

Iul= 10 log (1/1-0.5) = dB

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LINK BUDGET CALCULATION FOR UPLINK

The signal level at the RBS receiver (SSRBS) will be the outputpower of the UE (PUE) minus any losses plus any gains. Theselosses and gains are shown in Figure 4-8 below.

PUE

Gant Lpath

RBS Lf+jSS

RBS

Figure 4-8 Uplink link budget

The losses are:

Lpathis the path loss

Lf+J= Losses in feeder and jumper

The only gain is this example is that of the RBS antenna as the UEis assumed to have no antenna gain.

This is expressed in equation 19 below.

SSRBS= PUE Lpath+Gant Lf+j

Equation 19 Signal strength at RBS

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MAXIMUM PATH LOSS (LPATHMAX)

The ideal uplink budget would be where the signal level at theRBS (SSRBS) is equal or greater than the RBS Sensitivity(RBSsens).

In practice the loaded sensitivity should be used and the previousmargins and losses must be included in the link budgetcalculations.

This means that the SSRBS can be expressed as:

SSRBS= RBSsens(loaded)+ losses + margins

If the expression for SSRBS issubstituted into this formula itbecomes:

PUELpath+GantLf+j= RBSsens(loaded)+ losses + margins

Since RBSsens(loaded) = RBSsens+ IUL this formula becomes:

PUELpath+GantLf+j= RBSsens+ IUL+ losses + margins

SinceLosses = BL + CPL + BPL and margins = LNFmarg+ PCmargthe formula can be written as:

PUELpath+GantLf+j= RBSsens+ IUL+ BL + CPL + BPL + LNFmarg+ PCmarg

If this equation is solved for Lpaththen the maximum path lossallowed for the cell (Lpathmax) is given by equation 20 below.

Lpathmax= PUERBSsensIULLNFmargPCmargBL CPL BPL +GantLf+j

Equation 20 Maximum path loss (Lpathmax)

where:

Lpath is the path loss (on the uplink) [dB].

PUEis the maximum UE output power (= 21 or 24) [dBm].

RBSsensis the RBS sensitivity. [dBm].

LNFmargis the log-normal fading margin [dB].

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IULis the noise rise [dB].

PCmargis the power control margin [dB].

BLis the body loss (= 0 or 3) [dB].

CPL is the car penetration loss (= 6) [dB].

BPL is the building penetration loss [dB].

Gantis the sum of the RBS and UE antenna gains [dBi].

Lf+jis the loss in feeders and jumpers [dB].

This formula may be used to calculate the various maximum pathlosses for each service, as shown in Figure 4-9 below.

TU,

3 km/h

TU, 3 km/h

PS

TU,

50 km/h

TU, 50 km/h

PS Lpathmax

Lpathmax

Lpathmax

Lpathmax

Figure 4-9 Maximum uplink path losses

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WCDMA CELL RANGE

When roughly estimating the size of macro cells, without takinginto account specific terrain features in the area, the Okumura-Hata propagation formula can be solved for R to give equation 21below.

Rpathmax= 10, where = [Lpathmax- A + 13.82logHb+ a(Hm)]/[44.9 - 6.55logHb]

Equation 21 Maximum range using Okumura-Hata formula

where

A = 155.1 for urban areas

A = 147.9 for suburban and semi-open areas

A = 135.8 for rural areas

A = 125.4 for open areas


Hm= UE antenna height [m]


a(Hm) = 3.2(Log(11.75*Hm))2- 4.97

a(1.5) = 0

It must be emphasized that the Okumura-Hata formula only can beused for rough estimates. For more precise numbers, network-

planning tools should be used.

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For small cells in an urban environment the cell range is typicallyless than 1 km and in that case the Okumura-Hata formula is notvalid. The COST 231-Walfish-Ikegami model, gives a betterapproximation for the cell radius in urban environments.

The COST 231-Walfish-Ikegami model formula is solved for R togive equation 22 below.

Rpathmax= 10, where = [Lpath155.3 + 18log(Hb17)]/38

Equation 22 Maximum range using COST 231-Walfish-Ikegami

Note: The expressions above have been adapted to 2.05 GHz.

SITE COVERAGE AREA

This range may now be used to calculate the coverage area of thesite using equation 23, 24 or 25 for omni, three-sector and six

sector sites respectively as illustrated in Figure 4-10 below.

23

2

3RArea= 23

8

9RArea=

RSitetoSite 3

= RSitetoSite

2

3= RSitetoSite 3

=

23

2

3RArea=

R RR

Equation 23 Equation 24 Equation 25

Figure 4-10 Relationships between coverage area and cell range

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Example Uplink calculation

Complete Table 4-7 below for a three sector urban site to deliver95 % probability of coverage to AMR 12.2 kbps to TU 3 km UEs at50 % load.

PUE 21

RBSsens

Outdoor LNFmarg

PCmarg

IUL

BL

Gant 17.5

Lf+j 0

Lpathmax(outdoor)

CPL

Lpathmax(in-car)

BPL

Indoor LNFmarg

Lpathmax(indoor)

0.7

3

4.1

6

7.5

18

Table 4-7 Example UL Calculation

NOTE: the outdoor service is assumed to be pedestrians asopposed to users in vehicles.

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DOWNLINK DIMENSIONING

For the downlink it is not as easy to separate the coverage andcapacity in the way that is done for the uplink. The main differenceas compared to the uplink is that the UEs in the downlink shareone common power source. Thus the cell range is not dependentonly on how many UEs there are in the cell but also on thegeographical distribution of the UEs.

Despite orthogonal codes, the downlink channels can not be

perfectly separated due to multipath propagation. This means thata fraction of the BS power will be experienced as interference.Also, the downlink interference, caused by neighboring basestations transmitting channels that are not orthogonal to theserving base station, is user equipment position dependent.

The final equations are quite complex and difficult to use. In orderto facilitate the dimensioning process, curves have beengenerated based on the equations. The curves display the cellload (M/Mpole) versus the cell range. The curve for an urban 3-sector site is shown in Figure 4-11below.

Figure 4-11 DL capacity verses Cell Range

Typical parameter values have been used and 20% of the power

has been allocated to control channels. A homogenous user

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distribution has been assumed. To account for non-homogenous

distributions and log-normal fading a 5 W headroom has beenused. Thus the curves are based on a total power Ptot,sof 15 W

instead of 20 W. This roughly corresponds to 95% coverage

probability.

DOWNLINK LINK BUDGET

Before we can use this curve we must calculate the downlinkmargin DLmarg with equation 26 below.

DLmarg= BL + CPL + BPL +Gant+ Lf+j+ LASC+Nf +A0

Equation 26 Downlink Margin (DLmarg)

BLis the body loss.

CPLis the car penetration loss. Since this is an urban area car

loss will not be considered.

BPLis the building penetration loss.

Gantis the difference in antenna gain compared to the value usedin the curves.

Gant= 17.5Gant

Lf+Jis the loss in feeders and jumpers.

Nfis the difference in UE noise figure compared to the valueused in the curves

Nf= Nf7

LASCis the insertion loss of the ASC (if used).

A0is the difference of the distance independent term, in OkumuraHata, compared to the value used in the curves

A0= A0A0curves, where A0= A13.82 logHband A0curvesis134.68 or approx. 134.7

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4. WCDMA Coverage

LZT123 7628 - 111 -

Example Downlink Calculation

What load could a 40m, 3-sector Urban Cell cope with at a rangeof 1.5 km?

Firstly the DL margin must be calculated:

DLmarg= BL + CPL + BPL +Gant+ Lf+j+ LASC+Nf +A0

BL= 3 dB.

CPL= 0 dB

BPL= 18 dB

Gant= 17.5Gant ant = 0 dB

Lf+J5 dB (typical value)

Nf= Nf f= 0 dB

LASC=0.4

A0= A0- 134.7 but A0= 155.113.82 log(40)= 133 0 = 133 - 134.7 = -1.7 dB

Dlmarg= 3 + 0 + 18 + 0 + 5 + 0 + 0.4 -1.7 = . dB

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Where a line drawn through 1.5 km interecets the closestDLmargplot to .. will give the supported load of the cell asshown in Figure 4-12below.

Figure 4-12 Example DL Calculation

The maximum load supported by the cell is .. %.

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