GO NP04 E1 1 GSM Coverage Planning-60(New)

7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)

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GSM Coverage Planning

ZTE university



Contents

Overview of coverage planning

Link budget

Propagation model

Scale estimation Coverage enhancing technology

The common coverage issues Q&A



1. What is the purpose of coverage planning?2. What is the work content of coverage

planning?

3. What is the input of coverage planning?

4. What is the output of coverage planning?

1. Overview of coverage planning



1. What is the target of coverage planning?

Do the link budget and radius estimation for the targeted

coverage area so as to get to know the site scale and site

deployment which satisfy the KPI. Besides, if a digital map

is available, an adjustment can be done to the sites

according to the results of coverage simulation.

It is a must to have a three dimensional

digital map (Planet/EET) which coversthe whole targeted coverage area. Degree

of accuracy:

For urban areas: not lower than 20m;

For rural areas: not lower than 50m.



2. What is the work content of coverage planning?

Clarify the

input

Site

deployment

Link budget

Propagation

modelcalibration

Coverage

simulation

Scale

estimation

Coverage

plannin

g



3. What is the input of coverage planning?

•Which cities and major roads will be covered?

•What are the categories of scenarios according to theradio environment?

•What is the coverage range of each scenario?

The coverage requirements of each scenario:

•Coverage level

•Coverage probability

•Carry out a test and calibrate the parameters of the

propagation model.

•No test is carried out, and the parameters of the

standard propagation model are adopted.

•The equipment types, which will be adopted for the bidding,

depends on the market strategy.

•The biggest site configuration depends on the frequency bands and

the frequency resources.

•Is a Planet three-dimensional digital map available? The coverage

simulation can not do without the map.

•What about the application of the different kinds of coverage

enhancing technologies? ……

The size and range of the

target coverage area

KPI The coverage KPI

The parameters of the

propagation model

Others



4. What is the output of coverage planning?

Site scale

Site

deployment

Coverage

simulation

The balanced

budget of

uplink/downlink

power



1. Why is link budget needed?

2. What is path link balance?3. How can we judge a link is limited?

4. What is the result if a link is limited?

5. What is link gain and link loss?

6. What is slow fading?

7. What is fast fading?

8. What is coverage probability?

9. What is margin?

10. What kind of margin should be considered for the link budget?

11. What factors should be taken into consideration to decide the slow

fading margin which is frequently used?

12. What is design signal level and acceptance level?

13. What are the categories of combiner loss which are frequently come

across in link budget?

14. What factors should be taken into consideration to decide the power

of the set-top unit of ZTE series equipment?15. What factors should be taken into consideration to decide the

antenna and feeder loss of ZTE series equipment?

16. What is TMA?

17. How to choose the a suitable type of antenna?

18. How is the uplink/downlink budget calculated?

19. How to avoid the unbalanced link in network planning?

2. Link budget



1. Why is link budget needed?

The purpose of doing the uplink/downlink budget is toestimate the uplink/downlink coverage ability of the

system and to get the allowed maximum path loss of a

balanced link through an analysis of the factors which

influence the uplink/downlink signals during thetransmission.

The link budget is used to see how the uplink/downlink

borders of a cell is covered.



2. What is link balance?Strictly speaking, link balance means that the difference of

the path loss of the uplink radio link and that of thedownlink radio link is“0”.

Generally speaking, it is considered that there is a rough

link balance if the allowed maximum path loss difference

between the uplink and the downlink is no more than 2dB

when the link budget is calculated.

Downlink

coverage

Uplink coverage

Uplink coverage

=

Downlink

coverage



3. How can we judge a link is limited?

Uplink limited

Uplink coverage < Downlink coverage，that is,

The allowed maximum uplink path loss < The

allowed maximum downlink path loss

Downlink limited

Downlink coverage < Uplink coverage，that is,

The allowed maximum downlink path loss < The

allowed maximum uplink path loss

Uplink coverage

Downlink coverage

The part of invalid

downlink coverage

Downlink coverage

Uplink coverage

The part of invalid

uplink coverage



4. What is the result if a link is limited?

Uplink limited

In areas with problems, the handset has

signals but it can not originate a call;When the subscriber moves towards the

borders of a cell (areas with weak signals),

there may be unilateral conversations or call

drops.

When the subscriber moves from any other

area towards the uplink limited area which

is an area with problems, the success rate of

inward handovers of the cell will be affected.

Downlink limited

In the areas with problems, the handset is in

the coverage holes of the site, and it can not

originate a call.

When the subscriber moves towards theborders of a cell (areas with weak

signals), there may be unilateral

conversations or call drops.

Uplink coverage

Downlink

coverage

Areas with

problems

Areas with

problems





6. What is slow fading?

When the signals are transmitted, they will be blocked by the buildings and the

uneven land forms. In the areas where the signals are blocked, the shadow of

electromagnetic waves will be formed. As a result, the signal strength will be

weakened. This is called Shadow Fading, a kind of fading of signals, which is

caused by the shadow effect.

The signals go through a slow and random change within the range of dozens of

wavelengths, so the statistical counting obeys the rules of lognormal distribution.

Therefore, Shadow Fading is also called Slow Fading.

In English, it is called Slow Fading，or

Log-normal Fading，or Shadow

Fading.





Under the sameconditions, the areacoverage probabilityis larger than theedge coverageprobability. The twocan be mutually

transformed accordingto some rules in math.

8. What is coverage probability?

Coverage probability refers to how large the probability is that the received signal

of the terminal is larger than the threshold at the coverage borders of the cell (or within the coverage areas).

Coverage

probability

The edge coverage probability：The percentage of the cell borders whose

received signal is larger than the threshold.

The area coverage probability：The percentage of the areas whose received

signal is larger than the threshold.

The threshold level of the cell borders：-90dBm The threshold level of the cell borders ：-90dBm

The test is carried out along the covered cell

borders. The edge coverage probability refers to the

percentage of samples, of which the level is at least

- 90dBm.

The test is carried out along the paths of the covered areas

of a cell. The area coverage probability refers to the

percentage of samples, of which the level is at least -

90dBm.



9. What is margin?

When the radio signals are transmitted, they will have an

attenuation caused by different kinds factors of the radio

environment, for example, shadow effect, multi-path effect,

and so on. Therefore, the influence caused by these factors

should be taken into consideration when the design of radio

network starts. At the stage of network planning, some power

can be reserved to resist the possible attenuation. The

reserved power is called margin.



10. What kind of margin should be considered for the

link budget?--1

GSM is a kind of interference limited system. The received power should not only resist the noises

but also resist the co-channel/adjacent channel interferences which are caused by the frequency

reuse so as to ensure the quality of the signals. The power reserved to resist the interference is

called interference margin.

Usually it is 3dB.

1In order to ensure that the site can cover the cell borders with a certain probability,

the site must reserve some transmission power so as to overcome Shadow Fading.

So the reserved margin is called Shadow Fading margin or Slow Fading margin.

3

The multi-path effect of the transmission of radio signals will result in the fast fading of signals, so

the quality of signals will be affected. For GSM system, it resists Fast Fading by making use of a

series of technologies, including interleaving coding, frequency hopping, diversity reception,

adaptive equalization, and so on. Besides, at the stage of network planning, some design margin

should be reserved to resist Fast Fading. This is called Fast Fading margin. Usually, it is 3dB.

2

Slow Fading margin

Fast Fading margin

Jamming margin



10. What kind of margin should be considered for the

link budget?--2

Loss caused by the penetration of a car refers to

the attenuation which occurs when the radio

waves penetrate the car. It is equal to the

difference value when the median value of the

field strength of the signals outside the car and

that inside the car are compared.

Usually, it is 6～8dB.

4Body loss refers to the kind of loss which is caused by

signal blocking and absorption when the handset is held

quite close to the human body. Usually, for voice service, it

is 3dB;and for data service, it is 0dB.

6

Loss caused by the penetration of a building refers to the

attenuation which occurs when the radio waves penetrate theexterior structures of a building. It is equal to the difference value

when the median value of the field strength outside the building

and that inside the building are compared. The value related of

this kind of loss is closely related to the materials and thickness

of the building.

5

Body loss

Loss caused by the

penetration of a building

Loss caused by the

penetration of a car

Classification of

different areas

Typical

penetration loss

value

Dense urban 18～22Medium urban 15～20

Suburban areas

and rural areas

10～15



11. What factors should be taken into consideration to

decide the slow fading margin which is frequently

used?

Area TypeArea Coverage

Probability

Edge Coverage

Probability

Slow Fading

Margin (dB)

Dense Urban

Sigma=10dB

75% 54% 1

85% 69% 5

90% 80% 7.7

95% 88% 11.7

Medium Urban

Sigma=8dB

75% 50% 0

85% 66% 3.2

90% 75% 5.5

95% 86% 8.7

Suburban/Rural /Road

Sigma=6dB

80% 50% 0

85% 60% 1.6

90% 71% 3.4

95% 84% 5.9



12. What is design signal level and acceptance level?

The lowest level required SSmin_req

It refers to the lowest level required for making calls in real situations (outdoor/indoor/in a car).

On basis of the receiver sensitivity, it takes the following factors into consideration: Fast Fading

margin, interference margin, body loss, loss caused by the penetration of a building which is

relevant to a indoor subscriber or loss caused by the penetration of a car which is relevant to a

subscriber inside a car.

Design level SSdesign

In order to ensure a certain probability, it is necessary to consider the Shadow Fading

margin on basis of the lowest level required or the acceptance level. Then, the level value is

called design level. In other words, at the network planning stage, it is a must to consider

the possible influence exerted by Shadow Fading over the signal coverage. The purpose is

to ensure the network coverage probability.

Acceptance level SSacceptance

Usually, in the bidding documents or the contract, the client will mention the DT coverage KPI,

including the requirements for level value and coverage probability which DT should meet.

Then, the required level value which DT should reach is called the acceptance level by us.

However, if the client does not have any requirements for the acceptance level, we should

make a suggestion. Usually, it is considered that SSacceptance should be equal to SSmin_req

(SSacceptance = SSmin_req).

1

2

3



V2 series combiner loss

13. What are the categories of combiner loss which are

frequently come across in link budget?

1

Combiner 900M(d

B)

1800M(d

B) CDU 4.4 4.6

CEU 3.5 3.5

CEN 5.3 5.5

MCDU 4.4 4.6

ECDU 1 1

ECU 3.5 3.5

V3 series combiner loss

Combiner 900M(d

B)

1800M(d

B)

CDU 4.4 4.6

CEU 3.5 3.5

ECDU 1 1

2

SDR series combiner loss3

For RU02 and RU02A, the COM

loss is 3dB when it is S3~S4.

Other radio frequency processing

units do not have a combiner

inside.



14. What factors should be taken into consideration to

decide the power of the set-top unit of ZTE series

equipment?

TypeTransmiss

ion power Notes

V3

series

equip

ment

B8018 60wThe power of the set-top unit is closely related to the

configuration of carrier frequencies of the cell, the combiner

selected, and whether there is a new antenna or not. The

power of the set-top unit of GSM equipment with themodulation mode of 8PSK is about 2dB lower than that of

GSM equipment with the GMSK modulation mode.B8112 60w

M820230w（set-

top unit）

M8202 does not have a Combiner (either inside or outside).

The power of the set-top unit is always 30w(GMSK). The

power of the set-top unit of GSM equipment with the

modulation mode of 8PSK is about 2dB lower than that of

GSM equipment with the GMSK modulation mode.

M820630w（set-

top unit）

M8206 has a combiner outside, that is, ECU. If combining is

needed, it is necessary to take into account the loss of ECU

(3.5dB). The power of the set-top unit is 13w. The power of

the set-top unit of GSM equipment with the modulation mode

of 8PSK is about 2dB lower than that of GSM equipment with

the GMSK modulation mode.



14. What factors should be taken into consideration to decide the power

of the set-top unit of ZTE series equipment? - SDR Equipment

•Now multi-carrier RU/RRU

follows the principle of equipartition of carrier power ！ Carrier number RU02/RU02A RU60/R8860 RU80

GSM GMSK (W) GMSK (W) GMSK (W)

1 40 60 80

2 40 30 40

3 20 20 26.67

4 20 15 20

5 12 16

6 10 13.33

GSM

carrier

number

UMTS

carrier

number

RU60/R8860

GSM

GMSK (W)

UMTS (W)

1 1 40 20

2 1 20 20

3 1 13.33 20

4 1 10 20

1 2 20 20

2 2 10 20

The output power of set-top

unit of GSM with 8PSK

modulation is about 2dB lower

than that of GSM with GMSK

modulation.

•If the BS model configuration

for dual-carrier RU02/RU02A is

S3~S4, the loss for internal

combiner is 3dB.

1

2

GSM

single

mode

configur

ation

G/U

dual-

mode

configur

ation

For UMTS, the output power of

set-top unit per carrier must be

20W.



15. What factors should be taken into consideration to decide the

antenna and feeder loss of ZTE series equipment? – The

Typical Antenna and Feeder Connection

Without

TMAWith

TMA

Feeder

Type 900 1800 Unit

1/2” 11.2 16.6 dB/100m

7/8” 3.88 5.75 dB/100m

5/4” 2.77 4.16 dB/100m

13/8” 2.29 3.47 dB/100m

The table here shows the typical KPI of Hansen. It is just for

your reference. For a specific project, the table should be filledin according to the actual configuration of feeder line KPI.

If the feeder loss is more than

3dB, it is suggested that a

heavier feeder line should be

used.

Type Loss Unit

Connector 0.05 dB/eachT connector 0.3 dB/each

Lightning

arrester 0.2 dB/each

TMA

insertion loss 0.5 dB

•Increase the downlink insertion loss of

the tower amplifier (downlink).• Add one T connector and two other

connectors (uplink/downlink).

• Add some 1/2 soft jumper cable

(uplink/downlink).



What factors should be taken into consideration to decide the antenna

and feeder loss of ZTE series equipment? – Typical Antenna and Feeder

Connection

Installation near

an antenna

1

RRU and BBU is connected

by fiber ；

RRU and antenna is

connected by 1/2” jumper.

1. 2m ½” loss for softer jumper

2. 2 connector loss

Height of

antenna(m)

Height of

RRU on

platform

(m)

Length

of 7/8

main

feeder

line

(m)

Length

of ½

jumper

(m)

Connector

+

lightning

arrester

900M(d

B)

1800M(

dB)

50 0 50 4 6+1 2.89 4.04

50 10 40 4 6+1 2.5 3.46

50 20 30 4 6+1 2.11 2.89

50 30 20 4 6+1 1.73 2.31

50 50 0 2 2 0.32 0.43

1. 2×2m ½” softer jumper loss

2. Main feeder line loss between RRU and

the antenna

3. 6 connectors loss4. 1 feeder line lightning arrester loss

The table here is only for reference, in practice please

calculate according to specific conditions!

RRU is installed on the

platform of a tower (a platform under the antenna)

，or installed at the roof and

it is lower than the antenna

；

RRU and BBU is connected

by fiber ；

RRU and the antenna is

connected in a normal way.

The length of main feeder

line is the distance between

RRU and the antenna.

The installation

position keeps a

distance from

both BBU and

the antenna.

2



16. What is TMA?

TMA—Tower Mounted Amplifier

Tower Amplifier is the short form for Tower Mounted Amplifier. Actually, an

amplifier which has low noises and high linearity (low noise amplifier) is installed at

the front end of the receiving system of the site, a place, which is close to the

receiving antenna. It is used to amplify the uplink signals, to improve the noise

figure of the receiving system of the site, and to improve the uplink coverage

capability.

Q：Usually, the KPI designed for the uplink gain is 12dB. Does it follow

that 12dB uplink gain should be taken into consideration when the link

budget is calculated?

A：No. Since TMA is actually a low noise amplifier. On the one handthe valid uplink signals are amplified, on the other hand, different kinds

of noises and interferences are also amplified. The actual uplink gain

generated by TMA is usually 2～ 3dB.



17. How to choose the a suitable type of antenna?

Area Antennaheight（m）

Antenna gain（dBi）

Horizontalbeamwidth

of theantenna

Verticalbeamwidth

of theantenna

Polarizationcategories

Electrical downtilt

Dense urban 20～25 15.5~17 65 8～14 Dual-polarization

0～10 degreeelectrical downtilt

Urban areas 35～30 15.5~17 65 8～14 Dual-polarization

2～6 degreeelectrical downtilt

Suburban areas 35～40 17~18 65、90 7～10 Dual-polarization

2～4 degreeelectrical downtilt or without electricaldowntilt

Rural areas 45～50 17~18 65、90 7～10 Dual-polarization ,verticalpolarization

The electricaldowntilt is optional.

Highways or long and narrowvalleys

45～60 18~22 35 6～8 Dual-polarization ,verticalpolarization

The electricaldowntilt is optional.

If a single frequency antenna is used by a co-sited dual-band base station, the antenna selected for the 1800M

base station should be 1～2dB higher in antenna gain than that selected for the 900M base station. Usually, the

antenna of a 1800M base station is higher than that of a 900M base station by 3～5m.

If a dual-band antenna is selected, the installation space can be saved. However, the separate adjustment made

for the two networks will not be so flexible. It should be checked whether the antenna parameters of the two

frequency bands can both meet the relevant requirements.

In dense urban areas, an antenna with a lower antenna gain can be chosen if necessary.



18. How is the uplink/downlink budget calculated?

Parameter Symbol Unit

Transmission power of

the carrier frequency A dBm

Combiner loss B dB

Output power of the

set-top unit of BTSC=A-B dBm

Feeder line connector

lossD dB

Antenna gain of BTS E dBi

Antenna gain of MS F dBi

Receiver sensitivity of MS

G dBm

Fast fading margin H dB

Interference margin I dB

Body loss J dB

Loss caused by the


or a car

K dB

Slow fading margin L dB

The minimum level

required (DL)M=G+H+I+J+K dBm

Design level (DL) N=M+L dBm

Downlink enhancing

technologyO dB

The maximum

downlink path lossallowed

P=C-D+E+F-N+O dB

Parameter Symbol Unit

Transmission power of

MS A dBm

Antenna gain of MS B dBi

Antenna gain of BTS C dBi

Diversity gain D dB

Feeder line connector

lossE dB

The contribution to

sensitivity made by TMAF dB

Receiver sensitivity of BTS

G dBm

Fast fading margin H dB

Interference margin I dB

Body loss J dB

Loss caused by the


or a car

K dB

Slow fading margin L dB

The minimum level

required (UL)M=G+H+I+J+K dB

Design level (UL) N=M+L dB

Uplink enhancing

technologyO dB

The maximum uplink

path loss allowed

P=A+B+C+D-E+F-N dB

Choose the maximum path loss allowed for the link which is limited, that is, Min (P uplink, P downlink)as the maximum path loss allowed for the whole link!

Downlink Uplink



19. How to avoid the unbalanced link in network

planning?

The maximum uplink path loss allowed < The maximum downlink path

loss allowed, difference value > 2dBUplink limited Increase the

uplink coverage or decrease the invalid downlink coverage Link

balance

Solution: Add TMA, adopt 4 antennae to do the diversity reception, lower

the transmission power of the carrier frequency and so on.

The maximum downlink path loss allowed < The maximum uplink

path loss allowed, difference value > 2dB Downlink limited

Increase the downlink coverage Link balance

Solution: Increase the transmission power of the set-top unit of BTS,

increase the number of antenna and feeder, DPCT technology, DDT

technology and so on.



1. What is propagation model?

2. What are the categories of propagation model?

3. What are the frequently-used propagation

models?

4. Why is propagation model calibration necessary?

5. How to evaluate whether a propagation model is

suitable or not?

6. How to get a propagation model before the

calibration is done?

3. Propagation model



1. What is propagation model?

A propagation model is a kind of mathematical model which

describes and reflects the features of the transmission

environment of the radio signals and the rules for the

changes of the signals. Actually, a propagation model

represents a typical model of the transmission environment

which has some specific features.At the planning stage, the propagation model can be used in

the following two ways.

Estimation of thecell radius

Simulation



2. What are the categories of propagation model?Model Statistical model Deterministic model

Concept The propagationmodel is based on

the statistical

analysis of a large

quantity of testing

data.

The propagation modelis obtained through the

simulation of the multi-

path transmission

traces of the radio

waves. The simulation

is based on the

geometrical information

of the clutter and the

buildings which appear

on the transmission

path.

Amount of calculation Small Large

Computational accuracy Average Excellent

Requirements for theaccuracy of the digital map

20m~50m 1m~5m

The requirements for the

clutter of the digital map

The information of

the buildings is not

included.

The information of the

buildings must be

included.

Application range >1km <1km

Frequently-used models OKUMURA-HATA

COST231

VOLCANO



The frequently-used

propagation models

Okumura-Hata

Universal model

Volcano COST231

3. What are the frequently-used propagation models?

•0.5G~1.5GHz（For 900M） •Macro cell model•It is suitable for 900M sites wherethe simulation and scale estimationwill be done for a large quantity of sites in a wide range.

•1.5G~2GHz (For 1800M)•Macro cell model•It is suitable for 1800M sites wherethe simulation andscale estimation willbe done for a largequantity of sites in awide range.

•0.5G~2GHz (For 900/ 1800M)•Macro cell model•It is suitable for the sites where thesimulation and scale estimation will bedone for a large quantity of sites in a widerange.•At present, this model is adopted byAIRCOM/CNP.

•0.5G~2GHz•Micro cell model•It is suitable for aspecific area where thesimulation will be donefor a small quantity of sites.



4. Why is propagation model calibration necessary?

The radio transmission environment differs for each place due to the various land

forms, geographic features, distribution of buildings, coverage of vegetation, and so

on. For example, cities in plain areas VS cities in areas with hills, cities where there is

a dense distribution of high buildings VS cities where most of the buildings have 1～2

storeys, cites in desert areas VS cities in areas where there is a wide coverage of

vegetation … … Actually, propagation model calibration is necessary for each city.

The purpose is to get the parameters of the propagation model which is consistent

with the actual situation.

If the same set of parameters is applied to every scenario, it is quite possible that the

planning scheme differs greatly from the actual situation. Here are the consequences:

1. The network coverage which has been established is not good enough to meet the

coverage KPI.2. It is a large waste of resources if there are too many sites. Besides, severe

interferences may appear if there is a dense distribution of sites.



5. How to evaluate whether a propagation model is

suitable or not?

Before the calibration:

The Mean Error is not 0, the standard deviationStd Dev is large.Figure: The intersection point of the red line andthe vertical axis is not 0.0; the slope of the redline is not 0.

Horizontal ordinate: The logarithm of the distance betweenthe testing place and the base station is represented bylogd.Vertical ordinate: The Mean Error which is calculated bycomparing the actual level of the testing place and thepredicted level of that place is represented by Error.Dense dots: Testing placesThe red line: It shows a kind of tendency about what the Mean Error is likely to be when the overall actual testingvalues of the testing place are compared with thepredicted values.

After the calibration:The Mean Error tends to be 0, the standarddeviation Std Dev<=8dB. This means the model isquite consistent with the actual situation.(For dense urban areas, std dev<=10dB is alsoacceptable. );Figure: The intersection point of the red line andthe vertical axis is 0.0; the slope of the red line is 0.



6. How to get a propagation model before the calibration

is done?

Conditions

1. The digital map of the city for

which the planning will be done.

2. In the propagation model library,

there are a certain amount of

parameter sets related to the

propagation models, which are

reliable and accurate.

3. A tool used for choosing a model

automatically

If it is not possible to carry out the propagation model test or calibration of the

target city due to the problems of resources or time and the like, it is acceptableto choose a propagation model from the model library by following some certain

rules. This model can be regarded as an alternative choice, which should be

similar to the actual radio environment of the target city. However, there may be

some differences between the alternative choice and the actual situation.

As to the rules for choosing the model, they can be set up according to the

experience of the engineers or by using some customized automatic tool.Actually, this kind of tool will be applied to the Road Map of CNP.

Risks

It should be noticed that the model,

which is selected by using the tool, can

only be regarded as the most suitablemodel from the existing model library.

However, it does not mean that it is

completely matched with the actual

environment.



1. How to estimate the coverage radius of a

single site?

2. What’s the influence of downtilt over the

coverage?

3. How to calculate the site distance at the pre-

planning stage?

4. How to estimate the coverage area of a singlesite?

5. How to estimate the scale of coverage?

4. Estimation of the coverage scale



1. How to estimate the coverage radius of a single site?

Choose a universal propagation model:PL=k1+k2*lgd+k3*Hm+k4*lgHm+k5*lgHb+k6*lgHb*Lgd+k7*diffraction+ clutter LossHere,PL means the maximum path loss allowed for the whole link, which is calculated in the link budget.k1～k7 and Clutter Loss are the parameters which are obtained after the propagation modelcalibration. (As to the estimation of the radius, only k1 ～ k6 will be involved in the calculation.)

Hm is the height of MS.Hb is the effective height of BTS antenna.d refers to the distance between the base station and MS (km).When d of the model above is calculated in a reverse way, the following formula can be obtained.d=10^((PL-K1-K3*Hm-k4*lgHm-k5*lgHb)/(k2+k6*lgHb))Here d is actually the estimated coverage radius R of the base station.

Link budget Get the maximum path loss allowed for a whole link, that is, PL.1

Propagation model calibration Get the value of each parameter of the propagation model2

Calculate “d” of the propagation model formula in a reverse way Get the maximumcoverageradius of the site

3



2. What’s the influence of downtilt over the coverage?

When the maximum path loss allowed is calculated in the link budget, the influence

exerted by the downtilt is not taken into consideration. If the influence exerted by thedowntilt over the coverage is to be taken into consideration, the radius should be

estimated according to the following formula.

DT: Downtilt (mechanical downtilt +electrical downtilt)H: The antenna height of BTSAtan：Inverse tangent trigonometric

functionVB: Vertical 3dB beamwidth of theantennaDF: The distance to the farthest placewhich the upward 3dB beamwidth cancover. It is the predicted coverage radiuswhen the downtilt DT is taken intoconsideration.DN: The distance to the nearest placewhich the downward 3dB beamwidth cancover D: The distance covered by the main loberight ahead



3. How to calculate the site distance at the pre-planning

stage?

Three-sector

directional sites Omni sites

The distance between two three-

sector directional sites is 1.5R.R represents the radius of the

directional cell.

The distance between two omni

sites is 1.73R.R represents the radius of the

omni cell.

If two-sector directional sites are used for the

coverage of a long and narrow road, the distance

between the sites should be 2R.

R represents the radius of the directional cell.



4. How to estimate the coverage area of a single site?

A three-sector

directional siteAn omni site

Cell radius R

The coverage area

of a single cell0.65R2 2.6R2

The coverage area

of a single site1.95R2 2.6R2



5. How to estimate the scale of coverage?

MU

SU

For example,

According to the radio environment, the target city A

is divided into two parts, that is, the mean urban areaMU and the suburban area SU. The two areas are

represented by two polygons separately.

MU SU Notes

Cell radius km 0.5 1 R The estimated

radius R

The size of the coverage

area of a single cell km2 0.1625 0.65 0.65R2

The size of the coverage

area of a single site km2 0.4875 1.95 1.95R2

The size of the polygon

km2 4 10The size of the

polygon S

The number of BTSs(Num) 8 5 Num=S/(1.95R2)

The total number of

BTSs of the city A 13 =Num(MU)+Num(SU)



1. How many coverage enhancing technologies are

there?

2. What is bypass?

3. What is DPCT?

4. What is DDT?

5. What is FWDR?

6. What is IRC?

5. Coverage enhancing technologies

1 H h i h l i



1. How many coverage enhancing technologies are

there?

Uplink coverage

enhancing

Downlink

coverage

enhancing

Notes

TMA Bypass

DPCT and DDT can

not be used at the

same time.FWDR DPCT

IRC DDT



2. What is bypass?

Combiner

Duplexer

LNA

CDU

TX1 TX2 ETX

RX1

RX2

RX3

RX4

ERX

1

ERX

2

Combiner

Duplexer

LNA

CDU

ANT(RX/TX)

TX1 TX2 ETX

RX1

RX2

RX3

RX4

ERX

1

ERX

2

TRX1 TRX2

ANT(RX/TX)

TX RXM RXD TX RXM RXD

If a cell is configured with no more than 2 carrier frequencies, the TX interface of a carrier frequency

can be connected to the ETX interface of a CDU, then, it can be connected to a Duplexer directlywithout the use of a combiner.

When the link budget is calculated, only 1dB duplexer loss is considered, and the power of the set-

top unit is increased.



3. What is DPCT?

Dual Power Combining Transmission

DPCT means that two transmitters send the same bursts at the same time,

which are combined in the form of one carrier frequency through a

combiner so as to increase the output power.

From a physical perspective, DPCT can help to increase the power, so it is

especially suitable for areas which need a wide coverage.

The two signals have the same phase

and amplitude, and they are combined

within a carrier frequency module.

Theoretically speaking, 3dB downlink

gain can be obtained if one PA is

combined with another. However, if the

internal loss is taken into consideration,

the actual gain of DPCT is 2.5dB.



4. What is DDT?

Delay Diversity Transmission

DDT means that two carrier frequencies send the same signals at a slightly different

time. The signals are sent out by different antennae so as to get some time/space

diversity gain. In this way, the downlink coverage is enhanced. DDT is suitable for

some complicated radio transmission environment.

At BSC side, the main/auxiliary TRX can be regarded as one TRX, and the

parameters which the auxiliary TRX is configured with are the same as those whichthe main TRX is configured with. The quantity of signs inserted between them can be

configured at OMCR.

The downlink gain which can be generated by DDT is 2~3dB.

RF PA

RF PA

Phase adiust

algorithm

Phase adiust

algorithm



5. What is FWDR?

Four Way Diversity Receiving

FWDR means that 4 single antennae or 2 dual-polarized antennae are

used to make a single carrier frequency have four-way received signals.

Then, these signals are combined as a one-way signal through the

merging algorithm so as to enhance the diversity gain.

Compared to the two way diversity gain, FWDR can generate an extra 2～3dB gain for the uplink receiver sensitivity. Under the multi-path loss

condition, the dense urban areas which have a complicated transmission

environment can have a higher gain.



6. What is IRC?

IRC: Interference Rejection Combining

If the interferences of the diversity reception signals from two different ways are

relevant to each other, the relevance computing will be done for the noises of each

diversity branch to check the relevancy between the interferences and to combine the

signals accordingly. The purpose is to complete the interference rejection and to

improve the quality of the received uplink signals.

With IRC, C/I can get about 3～5dB gain in dense urban areas where the radio

environment is complicated.

MRC: Maximum Ratio Combining

If the interferences of the diversity reception signals on two different ways are not

relevant to each other, weighting and combining should be done to the signals from M

different ways.

If the interferences received from different antennae are notrelevant to each other, the performance of IRC is similar tothat of MRC. However, if the interferences are relevant to each other,IRC is much more stronger than MRC in terms of the interferencerejection ability.

6 Th f tl k d ti b t



1. What is a blind zone under a tower?

2. How to solve the problem if there is a blind zoneunder the tower?

3. What is weak coverage?

4. How to solve the problem of weak coverage?

5. What is overshooting?

6. How to solve the overshooting problem?

7. When is it called that there is not a serving cell?

8. What measures can be taken to solve the problem

that there is not a serving cell?

6. The frequently asked questions about

coverage planning Q&A



1. What is a blind zone under a tower?

Null: It refers to the deep fading point between thecentral lobe and the side lobe, or between two sidelobes.

-70dBm

-90dBm

-80dBm

-90dBm

A blind zone under a tower refers to a part of the user zone which needs to becovered, an area which is covered by the first null or the second null under the

vertical antenna radiation pattern. Compared to any other area which is either near or far, the signal strength of the blind zone under a tower may havegreater attenuation (20～30dB), and a weak coverage area is formed. As aresult, there may be a large number of subscriber complaints, and the KPIs of call drop rate and the like may be affected. The location of the blind zone under a tower is related to the antenna radiationpattern, the antenna height, and the transmission environment.

A blind zoneunder a tower



2. How to solve the problem if there is a blind zone

under the tower?

Null fill: The shaped-beam should be used to complete the first lower null fill of

the side lobe of the vertical pattern of the antenna so as to reduce the deepfading of the null.

Choose a null fill antenna;Choose an electrical downtilt antenna;Adjust the antenna downtilt appropriately so as to avoidthe blind zone under a tower in a dense user zone.

An antenna with a null fill An antenna without a null fill



3. What is weak coverage?

Weak coverage means that the signal level is too low to keep a

good call quality. It is usually believed that the coverage will beweak if the signal level is lower than -90dBm. If the coverage isweak, there will be many problems, for example, subscriber complaints, high call drop rate, and so on.

For example, the power of the set-top unit of the base

station is too small; the site planning is not reasonable;

the antenna height is too low according to its original

design; the inclination is too large; there is some

blocking because of the land forms or the buildings.

Concept

Causes

A weak coverage

area

A weak coverage

area



4. How to solve the problem of weak coverage?

At the network planning stage, more attention will be given tothe possible weak coverage areas. The following factors

should be taken into full consideration: The site location, the

antenna type, and the reasonableness of the designed

engineering parameters.

Increase the power of the set-top unit of the base station.

Check the decreased power problems caused by theequipment failures.

In the weak coverage areas, some base stations or repeaters

should be added.

?



5. What is overshooting?

Overshooting means that the actual coverage range of a

cell exceeds the range which has been designed

beforehand and an overlapping area is formed by this celland another cell which is far from it.

Overshooting may result in frequent handovers, an

increase of interferences, the islanding effects, and so on.

Here are the possible causes: The transmission power

of the base station is too large; the antenna lobe is toolarge; the antenna is too high; the inclination is too

small; there is an uneven land form; and so on.

Concept

Causes

A

B

C

Cell A is anovershooting

area.



6. How to solve the overshooting problem?One should be cautious when the site location is selected for a

highland or a mountain slope.

It should be ensured that the antenna type and the engineering

parameters of the antenna should be reasonably selected or designed

at the network planning stage.

The coverage area of the overshooting area should be controlled

through the adjustment of engineering parameters and the

transmission power of the base station.

If it is not possible to control the coverage at that time, it is suggested

that some neighbor cells should be added to the overshooting cell.

A

B

C

Enhance the neighbor cellrelations between A and C.

A

B

C

Control the coverage area of A.

7 Wh i it ll d th t th i t i ll?



There are frequent cell reselections when the handset is at an idle state.

In the cells at the borders of LAC, the location update occurs frequently due to the

frequent cell reselections. As a result, there will be an unnecessary increase of signalingload or congestion. Besides, there will be “ping-pong handovers” during the calls, and

the voice quality will deteriorate.

The transmission rate of the data service will be affected.

Because of the fluctuations of signals, there will be more subscriber complaints.

There are interferences, C/I is not satisfactory, and the voice quality deteriorates.

7. When is it called that there is not a serving cell?

For 2 or more cells, the signal strength of one cell is quite close to that of another cell, it is not

found that the signal strength of any cell has a big advantage over other cells. The handset has

frequent cell reselections when it is at an idle state, or there are “ping-pong handovers” during

the calls. The problems mentioned here are caused by the fact that there is not a serving cell.

The engineering parameters of the antenna are not designed in a

reasonable way.

The transmission power of the

carrier frequencies is too large or

too small.

The configuration of the

parameters is not reasonable ……

For the 3 cells in this area, thesignal level of each cell isalmost the same, so there isnot an obvious serving cell.

Concept

Influence

Causes

8 What measures can be taken to solve the problem



8. What measures can be taken to solve the problem

that there is not a serving cell? Adjust the antenna directional angle or the antenna

downtilt so as to ensure that there is a serving cell of

the coverage area, which has relatively strong and

stable signals.

Adjust the transmission power of the carrier

frequencies of the relevant cells so as to ensure that

there is a serving cell of the coverage area, which has

relatively strong and stable signals.

When the serving cell of the area is made clear, it is

suggested that the cell reselection parameters should

be adjusted so as to ensure that the subscribers can

reside in the serving cell as long as possible. In this

way, it is possible to relieve the frequent cell

reselections.

When the serving cell of the area is made clear, it is

suggested that the handover parameters of the cells should

be adjusted so as to reduce or eliminate the “ping-pong

handovers” during the calls.

1

2

3

4



Documents

GO NP04 E1 1 GSM Coverage Planning-60(New)