08 wo_np01_e1_0 umts scale estimation-55

7/28/2019 08 WO_NP01_E1_0 UMTS Scale Estimation-55

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Contents

1 UMTS Service Model....................................................................................................................................1

1.1 Service Classification...............................................................................................................................1

1.2 Service Model..........................................................................................................................................2

1.2.1 Classification of Area Types.....................................................................................................2

1.2.2 CS Domain Service Model.......................................................................................................3

1.2.3 PS Domain Service Model.......................................................................................................4

2 UMTS Coverage Estimation........................................................................................................................9

2.1 Radio Propagation Model........................................................................................................................9

2.1.1 Free Space Propagation Loss....................................................................................................9

2.1.2 Propagation Model.................................................................................................................10

2.2 Link Budget............................................................................................................................................12

2.2.1 Basic Link Budget Parameters...............................................................................................13

2.2.2 Unlink Budget.........................................................................................................................22

2.2.3 Uplink/Downlink Balance......................................................................................................22

2.3 Coverage Scale Estimation....................................................................................................................23

2.3.1 Calculation of BS Coverage Radius.......................................................................................23

2.3.2 Calculation of BS Coverage Area..........................................................................................24

2.3.3 Scale Calculation....................................................................................................................25

3 UMTS Capacity Estimation.......................................................................................................................27

3.1 Capacity Estimation Flow......................................................................................................................27

3.2 Estimation Method of Hybrid Service Capacity....................................................................................27

3.2.1 Equivalent Erlang Method......................................................................................................28

3.2.2 Post Erlang-B Method............................................................................................................29

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3.2.3 Campbell Method...................................................................................................................30

3.3 Uplink Capacity Estimation ..................................................................................................................32

3.3.1 Load Analysis for Uplink.......................................................................................................32

3.3.2 Uplink Capacity and Scale Estimation...................................................................................35

3.4 Downlink Capacity Estimation..............................................................................................................37

3.4.1 Analysis of Downlink Load....................................................................................................37

3.4.2 Downlink Capacity and Scale Estimation..............................................................................40

4 Scale Estimation Example..........................................................................................................................43

4.1 Assumed Conditions..............................................................................................................................43

4.2 Estimation Process.................................................................................................................................43

4.2.1 Estimation Flow Chart............................................................................................................43

4.2.2 Uplink Coverage Estimation..................................................................................................44

4.2.3 Uplink Capacity Estimation...................................................................................................46

4.2.4 Downlink Capacity Estimation..............................................................................................48

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Entertainment 64 128

WWW 64 128

FTP 64 128/384

Video streaming 64 384

1.2 Service Model

Service model is the reference for capacity estimation. It reflects the proportion of each

service in hybrid service under various service environments. Based on this proportion,

you can estimate the average traffic or data throughput of a single user. Multiply the

value by the expected number of users in various environments to get the

corresponding total traffic or throughput.

1.2.1 Classification of Area Types

Service model is very important to the UMTS network design because it is the

reference for capacity estimation and determines whether to take future network

service demands into account during planning. On the other hand, service model is

hard to predict. Service model is closely associated with the behavior habits of different

users using different services and users habits of using services are closely associated

with many factors in different areas, such as economy and culture. Therefore, a service

model is inapplicable for the application requirements of different environments.

According to service type distribution, service development policy and user dynamic

distribution as well as consumption behavior features in an area, service distribution

areas are categorized into six classes, downtown area, urban area, suburb area, rural

area, main line of communication/scenic spot and indoor coverage. Table 1.2-1 gives

service distribution features and user density of different areas.

Table 1.2-1 Service Distribution Features and User Density of Different Areas

Area

Service

Distribution

Feature

Site

Classification

User Density

(user/km2)

Population Density

(user/km2)

Downtown area Traffic-intensive

High service rate

requirement

Key area of data

service

Central business

district*

>12000>50000

Irregular

building-

intensive area

>8000 >30000

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UMTS Scale Estimation

Table 1.2-2 Voice Service Model

Area BHCA Call Duration (S) Traffic (Erl/BH)

Downtown

area

Central business

district2.7 60 0.045

Irregular

building-

intensive area

1.8 60 0.03

Dense building

complex area1.2 60 0.02

Urban area 1.2 60 0.02

Suburb area 1.018 60 0.018

Rural area 0.96 60 0.016

Main line of

communication/scenic spot0.9 60 0.015

Table 1.2-3 Video Phone Service Model

Area BHCA Call Duration (S) Traffic (mErl/BH)

Downtown

area

Central business

district0.135 120 4.5

Irregular

building-

intensive area

0.09 120 3

Dense building

complex area0.06 120 2

Urban area 0.06 120 2

Suburb area 0.0509 120 1.8

Rural area 0.048 120 1.6

Main line of

communication/scenic spot0.045 120 1.5

1.2.3 PS Domain Service Model

The data service call model widely differs from the voice service call model. Data call

has the following features:

Conversion between Dormant state and Active state;

Each session of a user can consist of several packet calls and different data service

types and user types have differentiated features;

Data is transmitted in data burst mode;

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international UMTS data service features, parameters of data service ETSI model in

downtown area are given in Table 1.2-5:

Table 1.2-5 Parameters of Data Service ETSI Model in Downtown Area

Service BHSA

Call per

Session

UL/DL

Packet

in a Call

UL/DL

Mean Packet

Size (Byte)

Throughput

UL/DL(kbits)

E-mail 0.3 2/2 15/15 480 34.56/34.56

MMS 0.05 2/2 15/15 480 5.76/5.76

Intranet 0.15 5/5 4/27 480 11.56/77.76

E-

commer

ce

0.05 2/2 10/26 480 3.84/9.98

Info

Services0.08 2/2 5/33 480 6.14/40.69

Entertai

nment0.02 5/5 4/27 480 1.54/10.37

WWW 0.2 5/5 2/15 480 7.68/57.60

FTP 0.15 1/1 8/74 480 4.61/42.62

Because all services will finally come down to the bear rate, Table 1.2-6 provides a

recommended data service model at the early stage of 3G construction based on bear

rate. Where, 384 service is applicable only for downtown and urban areas due to its

great impact on network coverage.

Table 1.2-6 Data Service Model

Bear

Rate

(kbps)

Busy Hour Traffic (kbits)Uplink/Downli

nk ProportionDowntown

AreaUrban Area Suburb Area Rural Area

64/64 80.64 63.04 38.8 15.76 1:1

64/128 161.88 140.3 87.35 34.94 1:7

64/384 112.51 86.8 54.25 21.7 1:10

Note: The data in this table is intended for Class 4 area, which relatively drops behind

Class 1, 2 and 3 areas so that you can multiply the data by 30, 20 and 10 respectively

for these areas. Overseas developed areas are taken as Class 1 areas.

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2 UMTS Coverage Estimation

2.1 Radio Propagation Model

2.1.1 Free Space Propagation Loss

Because of propagation path and landform interference, propagation signals are

decreased, which is known as propagation loss. In the space propagation, many factors

enter into radio wave loss, including ground absorption, reflection, refraction and

diffraction. In the case that radio wave is propagated in free space (homogeneous

medium with isotropy, imbibition and electric conductivity as zero), the above factors

are uncertain. However, it does not mean that there is no propagation loss of radio

wave in free space. After radio wave is propagated for a certain distance, it may also be

attenuated due to radiant energy diffusion (also called attenuation or loss).

When the transmitter whose transmission power is Pt eradiates radio signals through

isotropy antenna with gain as Gt, the signal power density Sr is:

24 dGtPtSr

=

The signal power Pr received by the antenna with gain as Gr is:

ArSr=Pr

Where, Ar stands for the effective receiving area of antenna,

4

2=

GrAr

then, ( )2

2

4Pr

dGrGtPt

=

Pt refers to the power from transmitter to transmit antenna.

refers to the electromagnetic wave length.

d refers to the distance between transmit and receive antennas.

Gt refers to the transmit antenna gain.

Gr refers to the receive antenna gain.

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The propagation loss is defined as the ratio of power from transmitter to transmit

antenna to power received by receive antenna:

( )2

24

Pr

==

GrGt

dPtLoss

Path loss is measured by dB, then space propagation loss (Loss) is:

( )( ) ( )GrGt

d

GrGt

dLoss lg10lg10

4lg20

4lg10

2

2

=

=

Propagation loss of free space (Free Loss) is:

= d

Loss

4

lg20

If and d are measured by Km and f is measured by MHz, the common formula

is:

fdFreeLoss lg20lg2044.32 ++=

From the above formula, we can see that the larger the distance (d) between transmit

antenna and receive antenna, and the larger the radio wave frequency (f), the larger the

free space loss. When d or f is doubled, the propagation loss of free space will be

increased by 6 dB.

2.1.2 Propagation Model

While planning and constructing a mobile communication network, you have to make

detailed study about electric wave propagation features and field strength prediction

before determining frequency band, frequency allocation and radio wave coverage,

calculating communication probability and inter-system electromagnetic interference,

and finally defining radio equipment parameters. The radio propagation model is a

mathematic formula of such variables as radio propagation loss and frequency,

distance, environment and antenna height concluded by theory study and practical test.

In the radio network planning, the radio propagation model presents the designer an

approximate propagation effect in the practical propagation environment to estimate

the space propagation loss. Therefore, the propagation model veracity determines

whether the cell planning is reasonable.

Radio propagation environments on the earth surface diversify a lot and propagation

models in different propagation environments are differentiated a lot, too. Therefore,

the propagation environment plays an important role in setting up a radio propagation

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Chapter 4 Scale Estimation Example

model. The propagation environment in a special region consists of the following

factors:

Terrains (mountains, hills, plain or water area)

Number, height, distribution and material features of buildings

Vegetation features

Weather conditions

Natural or man-made electromagnetic noise

Working frequency of system

Movement of mobile station

Propagation model is usually classified into outdoor propagation model and indoor

propagation model. The frequently-used models are shown in Table 2.1-1.

Table 2.1-1 Common Propagation Models

Model Name Frequency Range

Okumura-Hata 150 MHz1500 MHz macro cell prediction

Cost231-Hata 150 MHz2000 MHz macro cell prediction

Cost231 Walfish-Ikegami 800 MHz2000 MHz micro cell prediction

Keenan-Motley 900 MHz and 1800 MHz indoor environment prediction

General model 150 MHz2000 MHz macro cell prediction

The Cost231-Hata model and the General model used in the network planning software

Aircom are described below.

The Cost231-Hata model is applicable for 150 MHz2000 MHz macro cell prediction.

The urban path loss value can be worked out with the following approximate analysis

formula:

( ) mmbb CAhdhhfPathloss +++= lglg55.69.44log82.13lg9.333.46

Where, f refers to carrier, unit: MHz, applicable for 150 MHz2000 MHz;

bh refers to BS antenna height, unit: m, effective height 30 m200 m;

d refers to the distance from mobile station to antenna, unit: Km;

mAh refers to mobile station antenna height correction factor;

mC refers to city center correction factor, 3 dBm for large cities and 0 dBm for

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Table 2.2-1

Parameter Symbol Procedure

Transmitter power (dBm) A

Transmitting antenna gain (dBi) B

Transmitting-end human body loss (dB) C

Transmitting-end feeder loss (dB) D

Transmitting-end effective radiation power (dBm) E E=A+B-C-D

Thermal noise density (dBm/Hz) F

Thermal noise (dBm)G G=F+10*LOG(3840

000)

Receiver noise coefficient (dB) H

Receiver noise (dBm) I I=G+H

Interference margin (dB) J

Service bit rate (kbps) K

Processing gain (dB) L L=10*LOG(3840/K)

Eb/No (dB) M

Receiver sensitivity (dBm) N N=I+J-L+M

Receiver antenna gain (dBi) O

Receiver feeder loss (dB) P

Receiving-end human body loss (dB) Q

Power control margin (dB) R

Soft handoff gain (dB) S

Shadow fading margin (dB) T

Penetration loss (dB) U

Maximum allowed path loss (dB)V V=E-N+O-P-Q-

R+S-T-U

2.2.1 Basic Link Budget Parameters

This section describes basic parameters of the UMTS link budget.

1 Transmitter power:

BS transmitting power:

The maximum transmitting power of BS is 43 dB. The power of the Dedicated

CHannel (DCH) accounts for 63% of the total power. Table 2.2-2 shows the

power distribution of all channels:

Table 2.2-2 Power Distribution of Channels

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Power (dBm) Power (W) Proportion

Max Tx Power: 43.0 20.0 100.00%Pilot Power: 33.0 2.0 10%

PCCPCH(BCH): 30.0 1.0 5%

SCCPCH(FACH): 30.0 1.0 5%

SCCPCH(PCH): 30.0 1.0 5%

AICH: 26.0 0.4 2%

PICH: 26.0 0.4 2%

P-SCH: 29.0 0.8 4%

S-SCH: 29.0 0.8 4%

DCH 41.0 12.6 63%

The BS transmitting power is a system parameter, different for individual services. It

shall be determined in accordance with service type and service coverage.

MS transmitting power:

During link budget, suppose the maximum transmitting power of UE data

service to +21 dBm and that of voice service to +21 dBm.

The BS transmitting power is a system parameter, different for individual services. It

shall be determined in accordance with service type and service coverage. In the

network optimization process, optimization engineers shall adjust power distribution to

all channels in accordance with network quality and service requirement to provide the

whole network with the optimal performance.

2 Human body loss

It is generally 3 dB for voice service and 0 dB for data service.

3 Antenna gain

It is generally 0 dB for the UE.

During link budget, suppose the directional antenna gain of the BS to 17 dBi and

the omni-directional receiving antenna gain to 11 dBi. In practice, different

antennas can be selected in accordance with different region types and coverage

requirements.

4 Feeder loss

It includes the loss of all feeders and connectors between the equipment top and

the antenna connector. For a feeder of 30-40 meters long, suppose the total

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services under different multi-path channel conditions.

Table 2.2-3 Uplink Eb/No Value

UL Eb/No

(dB)

Urban Area Suburb Area

Service type Static TU 3km/h TU 50km/h RA 3km/h RA 50km/h RA 120km/h

AMR 12.2k 4.1 4.2 6.4 4.1 6 6.4

CS 64K 2.5 2.87 4.5 2.8 5.2 5.2

PS 64K 0.9 1.6 4.5 2.7 5 4.9

Table 2.2-4 Downlink Eb/No Value

UL Eb/No

(dB)

Urban Area Suburb Area

Service type Static TU 3km/h TU 50km/h RA 3km/h RA 50km/h RA 120km/h

AMR 12.2k 7.2 7.7 7.1 8.5 8.4 7.2

CS 64K 7.1 7.7 6.7 8.8 8.2 7.1

PS 64K 6.4 7.4 6.2 8 7.8 6.4

PS 128K 5.7 6.4 5.5 7.3 7.3 5.7

PS 384K 6.4 8 5.9 7.7 7.7 6.4

6 Interference margin

Interference margin = )1lg(lg10 , where indicates the cell load.

The UMTS system is of self-interference, and its coverage is closed related to

the system capacity. At earlier network stages, little traffic results in low value of

interference margin. As the traffic load increases, the interference margin

becomes larger and the BS coverage shrinks. With regard to link budget,

therefore, it is necessary to select the maximum uplink load in accordance with

the estimated traffic increasing trend to ensure good coverage.

The value of interference margin in the uplink budget depends on the capacity

requirement in the network design. The interference margin is 3 dB when the

load is taken 50% from the dense urban area or a cell in the urban area, it is 2.2

dB when the load is taken 40% from the suburb area, and it is 1.5 dB when the

load is taken 30% from the rural area.

For the downlink, the relationship between load and interference still exists. The

interference margin shall be determined by emulation because it is hard to make

the theoretic calculation.

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7 BS receiving sensitivity

BS receiving sensitivity indicates the minimum receiving level that the servicechannel requires to guarantee the decoding requirement with certain

communication qualities.

From the above deduction of Eb/No:

S(dBm) = Eb/No(dB) + N(dBm) - 10lg(W/R).

N indicates the total noise that the BS receives, that is, N = Noise + Nf + IM.

In the formula:

Noise indicates the thermal noise, caused by electronic thermal movements in

the conductor. It is generated between antenna and receiver as well as in the

damaged component coupler of level 1 of the receiver. In most of

communication systems, the power spectrum density is the same at the fixed

frequency point because the noise bandwidth is far larger than the system

bandwidth. From the DC to the frequency of 1012 Hz, therefore, the noise power

generated by the thermal noise source is the same per unit bandwidth. The

calculation formula of power is:

Noise = KTW (in the unit of W)

K indicates a Boltzmann constant, namely 1.38*10-23J/K.

T indicates the Kelvin temperature, namely 290 K.

W indicates the signal bandwidth, namely 3.84 M.

When dBm is taken as the calculation unit:

Noise = 10lg(KT) + 10lg(W).

10lg(KT) indicates the thermal noise density (in the unit of dBm/Hz).

Nf indicates the BS noise coefficient, defined as the ratio of input S/N to output

S/N. 3GPP does not have specific requirement for the equipment noise. It is

generally taken as 3 dB for link budget.

IM indicates the noise increasing caused by system load.

S(dBm) = Eb/No(dB) + 10lg(KTW) + Nf(dBm) + IM(dBm) - 10lg(W/R).

The formula of BS receiving sensitivity is:

Receiver Sensitivity = 10lg(KT) + Nf + 10lg(Eb/No) + 10lgR + IM.

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10lg(KT) indicates the thermal noise density, namely 174 dBm/Hz.

Nf indicates the BS noise coefficient, namely 3 dB.

IM indicates the interference margin.

8 Soft handoff gain

Here, soft handoff gain indicates the gain to overcome slow fading. When the

mobile equipment is located in the soft handoff region, multiple radio links of

soft handoff receive signals at the same time, which decreases the requirement

for the shadow fading margin. The soft handoff gain is generally taken as 3 dB

for link budget.

9 Power control margin (fast fading margin)

The UMTS system adopts the fast closed-loop power control of 1500 Hz. For a

low-speed mobile terminal, the fast closed-loop power control of 1500 Hz can

fight fast fading and guarantee the demodulation performance. Because of the

features of fast fading, however, the fast power control cannot compensate deep

fading when the low-speed mobile terminal is in deep fading. In this case, the

UE (Node B) needs to fight deep fading by increasing the average transmitting

power. When the UE is located at the edge of a cell, the fast power control

cannot compensate deep fading either. Therefore, it is necessary to reserve a

certain dynamic adjustment scope of transmitting power for the fast closed-loop

power control during link budget. The power control margin is generally taken

as 3 dB.

For a medium-speed or high-speed terminal (moving speed 50 km/hour), the

interleave in the channel code functions to fight fast fading while the fast closed-

loop power control has little function. So it is unnecessary to reserve the power

control margin.

10 Penetration loss

The penetration loss of buildings and vehicles is an important factor that

influences the radio coverage. The penetration loss is related to the specific

building/vehicle type and incident angle of radio wave. Suppose that the

penetration loss complies with lognormal distribution during link budget, and

use the average value of penetration loss and standard deviation to describe it. If

the radio coverage outside buildings is effective, it is enough to set the

penetration loss to 10 dB15 dB. To receive and initiate calls at the core part of a

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represented as:

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2.2.2 Unlink Budget

The parameters taken in the last section can be used to calculate the uplink budget

under different environments and coverage requirements. The following table shows

the calculation process:

Table 2.2-6 Uplink Budget

Parameter Symbol

Maximum transmitting power of UE A

UE antenna transmitting gain B

UE transmitting loss (human body loss) C

Actual maximum transmitting power of UE per

channelD= A +B C

Environment thermal noise power spectrum

densityE

Uplink noise figure F

Uplink receiving noise power spectrum density G = E +F

Uplink noise rise H

Total BS uplink receiving interference power

spectrum densityI = G + H

Uplink signal quality requirement Eb/No J

Uplink service rate K

Uplink receiving sensitivityL = I + 10lg(3.84*106) +(J 10lg (3.84*106/

k ))

BS antenna gain M

BS integrated loss N

Shadow fading margin P

Soft handoff gain Q

Power control margin R

Penetration loss S

Maximum loss T = D -L +M-N-P+Q-R-S

2.2.3 Uplink/Downlink Balance

Different from uplink budget, downlink budget makes all subscribers in the cell share

the BS power at the same time. The BS power distribution aims to make all subscriber

services connected with the BS in the cell match the corresponding service level.

Besides the number of subscribers in the cell, the downlink cell radius is also related to

the location and services of the subscriber.

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The following table shows the parameters that cause the maximum allowed path loss

difference between uplink budget and downlink budget. The downlink is usually

limited by the capacity. When the load of the cell increases, the condition of limited

downlink may occur.

Table 2.2-7 Uplink/Downlink Parameter Comparison

Parameter Uplink Downlink

Receiver noise coefficient (dB) 2.2 7

Maximum transmitting power (dBm) 21Depending on the maximum single-

channel transmitting power

Receiving-end Eb/No (dB) (12.2 kbps) 4. 2 7.2

The balance between the uplink and downlink needs the help of planning software for

iterative calculation. The calculation includes the uplink coverage estimation and the

downlink power distribution. It shows link balance if the total power does not exceed

the maximum BS transmitting power. If the total power required by the downlink

exceeds the maximum BS transmitting power, it is necessary to reduce the coverage

area and conduct the downlink power distribution again until the total power is smaller

than or equal to the maximum BS transmitting power.

2.3 Coverage Scale Estimation

2.3.1 Calculation of BS Coverage Radius

After acquisition of the maximum allowed path loss between MS and BS via link

budget, it is easy to estimate the BS coverage radius by combining with the local radio

propagation model. In fact, the radio propagation model describes the relationship

between path propagation loss and coverage distance. The maximum allowed path loss

and radio propagation model that have been known can be used to conversely deduct

the maximum BS coverage radius. If the coverage radius of macro-cell BS is to be

estimated only without considering the topographic features, the macro-cell radius can

be calculated by using the Cost231-hata model.

10=R( ) ( )bmmb hAhChfPathloss lg55.69.44/lg82.13lg9.333.46 ++=

Pathloss indicates the maximum allowed path loss, acquired via link budget.

f indicates the carrier frequency, in the unit of MHz.

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D

R

Area =23

8

9R , D = R

2

3

3 Six-sector directional BS

DR

Area =23

2

3R , D = R3

2.3.3 Scale Calculation

The planning region area divided by the single-BS coverage area is the number of BSs

that can cover the region with coverage requirements satisfied.

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3 UMTS Capacity Estimation

3.1 Capacity Estimation Flow

The capacity estimation is another important part of the scale estimation. The purpose

of capacity estimation is to estimate the approximate BS number needed by the

capacity according to the service model and service traffic demand of the network

planning. Similar with the link budget, the capacity estimation should be performed

from the uplink and downlink. For the UMTS system capacity, the interference is

limited in the uplink direction and the BS power is limited in the downlink direction. In

the 2 G CDMA network, the voice service is the main application service with

symmetrical uplink and downlink traffic, the capacity is limited in the uplink direction,

so the uplink capacity calculation is focused on in capacity estimation. However, in the

UMTS network, the data service proportion is obviously increased and the network

uplink and downlink traffic becomes asymmetric generally, and even the downlink

capacity may be limited. Therefore, the UMTS capacity estimation should be

performed from the uplink and downlink respectively. The following steps are involvedin capacity estimation:

1 Hybrid service intensity analysis. The UMTS system can provide multiple

services. The hybrid service intensity analysis makes the system capacity

consumed by various services equivalent to that consumed by a single service.

2 Uplink capacity estimation. Estimate the BS number that meets the service

demand based on the hybrid service intensity analysis.

3 Downlink capacity estimation. It is a verification process. The BS transmission

power formula is used to calculate the channel number that can be provided by

the current BS scale so as to verify whether this channel number can meet the

capacity requirement, and if it cannot, stations need be added.

3.2 Estimation Method of Hybrid Service Capacity

There are multiple services in the UMTS network, their service rates and required

Eb/No are diversified, the effects on the system load and consumed BS resources are

different, so the estimation for the cell capacity cannot adopt the method for estimating

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the cell capacity in a pure voice network. An idea of hybrid service capacity estimation

is to make equivalent among various services to make the system capacity consumed

by various services equivalent to that consumed by a single service. The Equivalent

Erlang, Post Erlang-B and Campbell methods in the hybrid service estimation are

introduced respectively as follows.

3.2.1 Equivalent Erlang Method

The fundamental principle of the Equivalent Erlang method is to make a service

equivalent to another service, calculate the total traffic (erl) of the equivalent services

and count the channel number needed by this traffic. We will give an example to

explain it as below.

Suppose services A and B are provided in the network, where,

service A: each connection occupies one channel and the total is 12 erl;

service B: each connection occupies 3 channels and the total is 6 erl.

If 1 erl service B is equivalent to 3 erl service A, the total traffic in the network will be

12+6*3=30 erl (service A). After querying Table erl-B, we know that altogether 39

channels are needed under 2% blocking rate.

If 3 erl service A is equivalent to 1 erl service B, the total traffic in the network will be

12/3+6=10 erl (service B). After querying Table erl-B, we know that altogether 17

service B channels (equivalent to 17*3=51 service A channels) are needed under 2%

blocking rate.

Upon the above analysis, we know that calculation result through the Equivalent

Erlang method is related to the equivalent mode adopted. The result through the former

equivalent mode is too small (39 channels) which is too optimistic, while the result

through the latter mode is too large (51 channels), which is too pessimistic, as shown inthe following figure:

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Capacities meeting the

same GOS are different

Low speed

service

equivalent

2 Erl Low

speed service

1 Erl High

speed service

High speed service

equivalent The calculation

result is related

to the

equivalent

mode

3.2.2 Post Erlang-B Method

The fundamental principle of the Post Erlang-B method is to calculate the channel

number required by each service capacity respectively and add channels in an

equivalent manner to obtain the channel number required by the hybrid service

capacity. We will give an example to explain it as below.




After querying Table erl-B, we know that altogether 19 channels are needed to meet

service A traffic (12 erl) under 2% blocking rate.

After querying Table erl-B, we know that altogether 12 service B channels (equivalent

to 12*3=36 service A channels) are needed to meet service B traffic (6 erl) under 2%

blocking rate.

The two services need 19+36=55 channels totally.

Calculate the network capacity in a special case based on the Post Erlang-B method:

Suppose services A and B are the same kind, where,



After querying Table erl-B, we know that altogether 19 channels are needed to meet

service A traffic (12 erl) under 2% blocking rate.

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After querying Table erl-B, we know that altogether 12 channels are needed to meet the

service B traffic (6 erl) under 2% blocking rate.

Services A and B need 19+12=31 channels totally.

Because services A and B are the same kind, the total traffic is 12+6=18 erl. According

to the currently known method of capacity calculation in single service, after querying

Table erl-B, we know that 26 channels are needed to meet the traffic demand under 2%

blocking rate. This result is correct obviously.

Upon above analysis, we can see that the calculation result through the Post Erlang

method is too pessimistic (31>26). The reason is that the BS channels are shared

among services, however, the Post Erlang method factitiously separates the channels

used by the services, and thus, the BS channel resource utilization ratio is reduced, as

shown in the following figure:

Capacities meeting the same

GOS are different

1 ERL service A

1 ERL service B

1 ERL service A and

1 ERL service B

The

calculation

result is too

pessimistic

3.2.3 Campbell Method

The fundamental principle of the Campbell method is to make all services equivalent to

a virtual service based on certain rules, calculate the total traffic (erl) of this virtual

service, count the virtual channel number needed by this traffic, and convert the

number into the actual channel number that meets the network capacity.

The equivalent principle of the Campbell model:

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==

iii

i

ii

aerl

aerlv

c

2

cfficOfferedTra

=

c

aCCapacity ii

)( =

Where, c indicates capacity factor.

v indicates hybrid service variance.

indicates hybrid service mean.

ia indicates the equivalent intensity of service i.

iC indicates the channel number needed by service i.

OfferedTraffic indicates traffic of the virtual service.

Capacity indicates the virtual channel number needed by the virtual traffic.

We will give an example to explain it as below.




Equivalent intensity of service A a1=1 and that of service B a2=3.

The hybrid service mean is =+==i

iiaerl 3036112

The hybrid service variance is =+==i

iiaerlv 663611222

The capacity factor is2.2

30

66===

vc

The virtual traffic is63.13

2.2

30===

cfficOfferedTra

After querying Table erl-B, we know that altogether 21 virtual channels are needed to

meet the virtual traffic under2% blocking rate.

According to formula (), under 2% blocking rate, the channel number needed by each

service is shown as follows:

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Service A:471)2.221(1 =+=C

Service B:

493)2.221(1 =+=C

From the above analysis, compared with results of the Equivalent Erlang and Post

Erlang-B methods, the result of the Campbell method is more credible, so it is a more

reasonable estimation method for hybrid service capacity at present. According to the

Campbell method, under the same requirement of the service level GOS, diversified

channel resources are needed by different services, or, under the same channel

resources, different services obtain diversified service levels. From this point of view,

the Campbell method is more reasonable. However, the Campbell method makes all

services uniformly equivalent as the circuit domain services and uses the Erlang-Bmodel for analysis and calculation. In fact, the features of the packet domain services

are completely different from those of the circuit domain services, and in addition, the

Erlang-B establishment conditions are not satisfied, so this equivalent method has

defects itself. A further research is needed for better hybrid service establishment

model and capacity analysis method.

In the Campbell method, the service equivalent intensity a can be calculated based on

channel number consumed by each kind of service or based on the interference

introduced from the air interface by each kind of service, shown as follows:

1amplitudefor1amplitudeforratebit

serviceforserviceforratebit

amplitudeRelative

0

0

N

E

N

E

b

b

=

If the reference service is the voice service, with its activity at the physical layer

considered, the above formula can be modified to:

for voicevfor voicefor voiceratebit

serviceforserviceforratebitamplitudeRelative

0

0

=

N

E

N

E

b

b

3.3 Uplink Capacity Estimation

3.3.1 Load Analysis for Uplink

In the UMTS system, all users adopt the same carrier and each signal becomes a noise

(interference) for others upon coding. Therefore, each signal is contained in the

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UL

NR

=1

1

or)1(10)( 10 ULLOGdBNR =

This equation reflects the thermal noise lifting caused by user interference at the BS

receive end. 3 dB noise lifting corresponds to 50% load factors and 6 dB noise lifting

corresponds to 75% load factors. Generally, the network planning supposes that the

uplink load factor is 50%, in a single service, the channel number provided by each cell

can be calculated through formula (1), and then, the total BS number required by the

uplink capacity demand can be counted further. For the capacity estimation for hybrid

service, the Campbell algorithm should be combined to make the system resources

consumed by various services equivalent to those consumed by a single service. Then,

the channel number provided by each cell can be calculated through formula (1), and

the BS number required by the hybrid service capacity demand can be counted further.

The next section details the capacity estimation flow of the hybrid service.

The uplink noise lifting NR corresponds to the interference margin in the uplink

budget, that is, the coverage is related to the capacity. In planning, the network load

factor should be determined to get the noise lifting corresponding to this load. Then,

the BS radius meeting the uplink capacity requirement can be calculated further

through the link budget.

3.3.2 Uplink Capacity and Scale Estimation

The previous section describes the load factor of uplink, based on which, this section

describes how to estimate the BS quantity satisfying the composite traffic requirements

for uplink. Figure 3.3-1 shows the flow of estimating uplink capacity.

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Calculate equivalent

intensity of services

Calculate the variance,

average value and capacity

factor of the mixed service

Virtual traffic A of the

system

Calculate the quantity

of equivalent voice channels

in a cell

The quantity of virtual

channels in the sell

Virtual traffic B of the cell

Number

of cells

A/B

Error:

Reference source not found

Figure 3.3-1 Flow Chart of Estimating Uplink Capacity

1 Calculate the virtual composite traffic of the system.

Because various services have different effects on system load, such an effect

can be equivalent to the effect of multiple voice channels on system load. The

calculation formula is as follows:

amplitude service= (Rservice x Eb/Noservice x vservice)/ (Rvoice x Eb/Novoice

x voice)

Where, R represents service rate.

Eb/No represents quality factor of the service.

v represents the activation factor of the service at the physical layer

According to the Campell theory, the virtual composite traffic of the system can

be calculated.

2 Calculate the quantity N of equivalent voice channels provided by a cell.

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the location of users. For the average value of cell load factors, adopt its similar

average value in the whole cell, that is:

=

+=

N

j j

jjDL i

RW

NoEbv

1

])1[(/

)/(

Where, represents the average quadrature factor in a cell. Generally, it is 60% for

the multipath channel and 90% for the non-multipath channel. i represents the

average ratio of the BS power received by the user from other cell to that from this cell.

Generally, it is 55% for the omni antenna macro cell and 65% for the three-sector

antenna macro cell.

During the analysis of downlink capacity, estimation of BS transmitting power is the

most important. The estimated BS transmitting power is average power not peak power

at the cell boundary, because the transmitting power distributed by the BS for each user

is determined by the average loss from the BS to the mobile station and the sensitivity

of the mobile station. On the actual network, users are distributed randomly in a cell,

not at the cell boundary, therefore, the average path loss value, not the maximum path

loss value estimated for the link, should be adopted when BS transmitting power is

calculated. In a macro cell, the difference between the maximum path loss and the

average path loss is usually 6 dB.

The total BS transmitting power can be expressed by the following formula:

DL

N

j j

j

jrfRW

NoEbvLWN

TxPBS

==

1

/

)/(

_1

Where, rfN

represents the noise power spectrum density on the front of the mobile

station receiver, and it can be calculated by the following formula:

)290(sup0.174 KposeTNFdBmNFKTNrf

=+=+=Where, NF

represents the noise coefficient of the mobile station receiver with the typical value of 5

dB to 9 dB.

L represents the average path loss, which is evaluated by subtracting 6 dBm from the

maximum path loss.

vj represents activation factor of the user j.

Rj represents bit rate of the user j.

In the case of a single service, evaluate the channel quantity provided by every cell

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under the maximum allowed transmitting power according to the formula (2) and

further evaluate the total number of BSs satisfying downlink capacity requirements.

In fact, the analysis of uplink and downlink link performances is a hard process.

Because the performance of downlink depends on many basic elements very much, its

analysis cannot be streamlined like the analysis of uplink. The Eb/No value range of

downlink is a parameter changing greatly with moving speed and multipath condition.

In addition, the mobile station receiver does not use antenna diversity. The reason why

the required Eb/No value changes with the mobile station is that at least two paths

cannot be ensured unless it is clearly known that the mobile station is in soft handoff or

softer handoff statuses. Such a change, randomicity of mobile station location and

interference level from the surrounding cell make the analysis of downlink

performance complicated. In designing, a very conservative conclusion can be gotten

in the case the worst condition is considered. Generally, estimate capacity after

analyzing the channel quantity required by uplink capacity, and observe whether the

downlink can support the mobile station to work in the designated coverage area and

its channel quantity reaches the channel quantity generated by the uplink.

3.4.2 Downlink Capacity and Scale Estimation

Downlink estimation is a verification process. The process of downlink capacity and

scale estimation is as follows: First calculate the quantity of equivalent voice channels

to be provided by this cell in the current service model, and then calculate the quantity

of equivalent voice channels availably provided by the cell according to the downlink

power calculation formula, and subsequently compare these two results. If the quantity

to be provided by the cell is less than that availably provided by the cell, it indicates

that downlink power is enough and the current scale satisfies system capacity

requirements. If the former is larger than the latter, it indicates that downlink capacity

is limited. To make downlink power enough, add some BSs.

1 Calculate the quantity of equivalent voice channels to be provided by every cell.

Under the precondition of known reverse capacity and scale, you can evaluate

the traffic of various services in every cell under such a scale. Then, according to

the equivalence of voice channels, you can evaluate the quantity of equivalent

voice channels to be provided by every cell. This quantity can be calculated by

following several steps below

1) Calculate the average traffic of various services in every cell according to the BS

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quantity of uplink and total traffic of downlink.

Average traffic of various services in a cell=

3ntityStationQuaUplinkBase

inkTrafficTotalDownl

Where, the BS quantity is the larger value between estimated uplink coverage

and estimated capacity result.

2) According to the Campell theory, calculate the virtual Erlang traffic in every cell.

The calculation method in this step is the same as that of uplink.

3) Look up Table Erl B according to the virtual Erlang traffic in every cell

evaluated in step 2, and calculate the quantity of virtual channels in every cell.

4) According to the quantity of virtual channels evaluated in step 3 and the

following formula

c

aCCapacity ii

)( =

you can evaluate the quantity of equivalent voice channels to be provided by

every cell.

2 Calculate the quantity of equivalent voice channels availably provided by thecell.

According to the forward power formula

])1[(/

)/(*1

/

)/(***

1

1

jj

N

j j

jj

N

j j

jjN

RW

NoEbv

RW

NoEbvLP

P

+

=

=

=

Where, PN represents the noise power spectrum density on the front of the

mobile station receiver, and it can be calculated by the following formula:

)290(sup0.174 KposeTNFdBmNFKTPN =+=+= ,

NF represents the noise coefficient of the mobile station receiver with the typical

value of 5 dB to 9 dB.

L represents the average path loss, which is evaluated by subtracting 6 dBm

from the maximum path loss. j represents the average quadrature factor.

Generally, it is 0.6 for the multipath channel and 0.9 for the non-multipath

channel.

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Input:system load requirment and

coverage requirement

Uplink coverage

estimation

Quantity of BSs

satisfying uplink

coverage

Downlink coverage

estimation

Quantity of BSs

satisfying downlink

coverage

Compare the results

and evaluate the

larger one

Uplink capacity

estimation

Quantity of BSs

satisfying uplink

capacity

End

Based on traffic type Based on power

Quantity A of

channels to be

provided by every cell

on the downlink

Quantity B of

channels availably

provided by every

cell on the downlink

AddBSs

No

Yse

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loss (dB) + BS receiving antenna gain (dBi) + soft handoff gain (dB) building

or car body penetration loss (dB) slow fading margin (dB) power control

margin (dB) interference margin (dB) BS receiving sensitivity (dBm)

Values in the following table can be obtained according to parameters in Section

4.2.1:

Voice CS64 PS64 PS64/128 PS64/384

Transmitting

end

Maximum transmitting

power (dBm)21 21 21 21 21

Antenna gain (dBi) 0 0 0 0 0

Human body loss (dB) 2 0 0 0 0

Effective transmitting power 19 21 21 21 21

Receiving

end

Thermal noise power

spectrum density (dBm/HZ)-174 -174 -174 -174 -174

Thermal noise power (dBm) -108 -108 -108 -108 -108

Receiver noise coefficient

(dB)2.2 2.2 2.2 2.2 2.2

Receiver noise (dBm) -105 -105 -105 -105 -105

Interference margin (dB) 3 3 3 3 3

Bit rate (kbit) 12.2 64 64 64 64

Processing gain (dB) 24.98 17.78 17.78 17.78 17.78

Receiving Eb/No (dB) 4.2 2.87 1.6 1.6 1.6

Receiver sensitivity -124 -118 -119 -119 -119

Antenna gain (dBi) 17 17 17 17 17

Line loss 4 4 4 4 4

Others

Power control margin 3 3 3 3 3

Soft handoff gain 3 3 3 3 3

Shadow fading margin 10.3 10.3 10.3 10.3 10.3

Penetration loss 20 20 20 20 20

Maximum allowed path loss 125.34

121.4

7

122.7

4 122.74 122.74

2 Calculate the cell coverage radius according to a specific propagation model

Here, we adopt a universal propagation model of Aircom to calculate:

Path loss = k1 + k2log(d) + k3Hms + k4log(Hms) + k5log(Heff) +

k6log(Heff)log(d) + k7(diffraction loss) + clutter loss

Use parameters in the following table

k1 152.4

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k2 44.6

k5 -13.82

k6 -6.55

Heff 30

K1 and K2 parameters have greater effect on the budget result. While, K3 and K4 have

less effect, so their values are 0.

Obtain the BS coverage radius after adopting the maximum path loss:

Voice CS64 PS64 PS64/128 PS64/384

Radius (Km) 0.65 0.5 0.54 0.54 0.54

3 Calculate the number of BSs required by uplink

From the result in the previous step, we see that the uplink coverage is limited

by the CS64kps service, so the BS radius satisfying successive coverage of

CS64kps is adopted when the number of BSs is calculated.

If the coverage area S of the three-sector BS =23

8

9R = 1.95 0.52= 0.488

Km2

The number of BSs satisfying uplink coverage requirement is 40.8/0.488 = 84

For downlink budget, because all users in the cell share BS power simultaneously, the

cell radius on the downlink is not only related to the number of users in the cell, but

also related to user location and services used by users. The balance between the uplink

and downlink should be calculated iteratively with the planning software. First predict

coverage area for the uplink, and then allocate power for the downlink. If the total

power does not exceed the maximum transmitting power of the BS, links are balanced.

If the total power required by the downlink exceeds the maximum transmitting power

of the BS, coverage area should be reduced and power should be re-allocated to the

downlink until the total power is less than or equal to the maximum transmitting power.

4.2.3 Uplink Capacity Estimation

1 Calculate the virtual composite traffic of the system.

1) Equivalent service intensity of each service

According to the formula

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1amplitudefor1amplitudeforratebit

serviceforserviceforratebit

amplitudeRelative

0

0

NE

N

E

b

b

=

obtain

voice: 1

CS64: 64 x 1 x 100.287/12.2 x 0.67 x 100.42 = 5.76

PS64/64: 64 x 1 x 100.16/12.2 x 0.67 x 100.42 = 4.3

PS64/128: 64 x 1 x 100.16/12.2 x 0.67 x 100.42 = 4.3

PS64/384: 64 x 1 x 100.16/12.2 x 0.67 x 100.42 = 4.3

2) Calculate the mean of composite traffic

=++++==i

iiaerlmean 1.57663.423.453.410067.540013000

3) Calculate the variance of composite traffic

=++++==i

iiaerliance 1823.423.453.410067.540013000var2222

4) Calculate the capacity factor

capacity factor= variance/mean = 3.17

5) Calculate the virtual composite traffic of the system

composite traffic = mean/capacity factor= 5766.1/3.17 = 1818.96 (Erl)

2 Calculate the quantity N of equivalent voice channels availably provided by the

cell

According to the uplink load formula

+

+=

N

j

o

bj

N

EvR

Wf

1*

1*1

1*)1(

Where, %50= and 65.0=f

get the quantity of equivalent voice channels N = 54

3 Calculate the quantity of virtual channels in every cell

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According to

c

aCCapacity

ii )(

=

get the quantity of virtual channels in the cell = (54 1)/3.17 = 16

4 Look up Table Erl B according to the quantity of virtual channels evaluated in

step 3, and get the quantity of virtual traffic in every cell, that is 9.83 Erl.

5 Calculate the number of cells

Number of cells = Virtual traffic of the system/virtual traffic of every cell =

1818.96/9.83 = 186

The number of required three-sector BSs = 186/3 = 62

After the above calculation, we know that 84 stations are required for uplink

coverage. The evaluated number of stations is less than 84, so it meets both

coverage and capacity requirements.

4.2.4 Downlink Capacity Estimation

Downlink capacity estimation is a verification process. With the downlink power

formula, verify whether the number of BSs evaluated from uplink coverage and

capacity budget meets the power requirement. Add BSs until downlink power meets

the requirement.

1 Calculate the quantity of equivalent voice channels to be provided by every cell.

1) Calculate the average traffic of various services in each cell according to the BS

quantity of uplink and total traffic.

Average traffic of various services in every cell is:

Voice: 3000/84/3 = 11.9 Erl

CS64: 400/84 = 1.59 Erl

PS64/64: 100/84 = 0.4 Erl

PS64/128: 35/84 = 0.14 Erl

PS64/384: 20/84 = 0.079 Erl

2) Calculate the virtual Erlang traffic in every cell.

Equivalent service intensity of each service on the downlink

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Voice: 1

CS64: 64 x 1 x 10

0.77

/12.2 x 0.67 x 10

0.77

= 7.8

PS64/64: 64 x 1 x 100.74/12.2 x 0.67 x 100.77 = 7.3

PS64/128: 144 x 1 x 100.64/12.2 x 0.67 x 100.77 = 13.1

PS64/384: 144 x 1 x 100.8/12.2 x 0.67 x 100.77 = 50

The mean of composite traffic is

Mean = 11.9 1 + 1.59 7.8 + 0.4 7.3 + 0.14 13.1 + 0.079 50 =

33.04

The variance of composite traffic is

Variance = 11.9 1 + 1.59 7.82 + 0.4 7.32 + 0.14 13.12 + 0.079

502 = 355.19

Capacity factor = variance/mean = 355.19/33.04 = 10.75

Virtual traffic of the cell

composite traffic = mean/capacity factor = 33.04/10.75 = 3.07 (Erl)

3) Check Table Erl B and obtain that the quantity of virtual channels required by

every cell is 7

4) Calculate the quantity of equivalent voice channels required by each cell.

According to the formula

c

aCCapacity ii

)( =

evaluate the quantity of equivalent voice channels is: 7 10.75 + 1 = 76.

2 Calculate the quantity of equivalent voice channels actually provided by every

cell.

According to the downlink power formula

])1[(/

)/(*1

/

)/(***

1

1

jj

N

j j

jj

N

j j

jjN

RW

NoEbv

RW

NoEbvLP

P

+

=

=

=

Where, P represents the maximum service transmitting power, which is 13 W.

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PN represents the noise power spectrum density on the front of the mobile station

receiver, and its value is -169 dBm.

L represents average path loss, which is evaluated by subtracting 6 dBm from

the maximum path loss.

j represents average quadrature factor, which is 0.6 for the multipath channel.

j represents interference factor from an adjacent cell. It is 0.65 for the three-

sector antenna macro cell.

Obtain that the quantity of equivalent voice channels actually provided by every

cell is 71.

3 Comparison

Through downlink budget, the quantity of channels required by every cell is 76

when there are 84 BSs in a network. However, according to the power formula,

the quantity of channels actually provided by every cell under the current scale

is 75. That is, downlink power cannot meet the requirement. To meet such a

requirement, add some BSs.

Obtain the following table through successive iterative calculation:

BS Quantity Required Channel Quantity Provided Channel Quantity

83 76 71

84 76 71

85 76 71

86 76 71

87 76 71

88 65 71

If there are 88 BSs, the uplink and downlink coverage capacity requirement can be

met.

In the case, the BS coverage radius is 488.095.1/88/8.40 = Km

08 wo_np01_e1_0 umts scale estimation-55

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