coverage planning course

8/8/2019 Coverage Planning Course

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

Coverage Planning Principle

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Page2Copyright 2008 Huawei Technologies Co., Ltd. All rights reserved.

Contents

1. Planning Basis

2. Coverage Planning

3. Advance Planning

4. Advance Technology for improving coverage



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Radio Propagation Environment

Multi-path propagation

Shadowing

Terrain

Building

Reflection

Interference



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Reflections

direct signalstrong reflected signal

equalizer window 16 s

amplitude

delay time

long echoes, out of equalizer window:self-interference

Strong echoes can cause excessive transmission delay

No impact If the delay falls in the equalizer window

Cause self-interference if the delay falls out of the equalizer window



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Fading

Slow fading (Lognormal Fading)

Shadowing due to large obstacles on propagation direction

Fast fading (Rayleigh fading)

Serious interference from multi-path signals



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Fading

time

power

2 sec 4 sec 6 sec

+20 dB

meanvalue

- 20 dB

lognormalfading

Rayleighfading



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Objective of Propagation Model

The propagation model is used to estimate the path loss

during radio wave propagation caused by the terrain and

artificial environments

The propagation model is the foundation of the coverage

planning. A good model mean more precise planning.

The propagation model depends on the working frequency

of the system. Different propagation models have different

working frequencies ranges. Moreover, indoor propagation

model differs from the out door propagation model

Through surveying radio propagation environments, you can get familiar with the

overall landforms, estimate the rough antenna height, and select the proper radio

propagation model, among which the radio propagation model helps you estimate

the number of base station when predicting the coverage. If necessary, you must

adjust the propagation model.



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Contents

1. Planning Basis


3. Advance Planning




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Cell Coverage Range

Achievable cell coverage depend on

Frequency band (450, 900, 1800 MHz)

Surroundings and environment

Antenna type

Antenna direction

Minimum required signal level

Difference band coverage area will be difference. Normally



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Min. Receiving Level

On Down Link

On Uplink

npenetratioinm

inminmmsreceive

LFastFading

ngSlowlyFadiISMin

++

++=

arg

argarg

npenetratioinminminmbtsreceive LFastFadingngSlowlyFadiISMin ++++= argargarg



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Fading

Slow fading (Lognormal Fading)

Shadowing due to large obstacles on propagation direction

Fast fading (Rayleigh fading)

Serious interference from multi-path signals

+10

0

-10

-20

-300 1 2 3 4 5 m

Level (dB)

920 MHzv = 20 km/h



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Fading

time

power

2 sec 4 sec 6 sec

+20 dB

meanvalue

- 20 dB

lognormalfading

Rayleighfading



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Min. Receive Level

Sms=-102dBm

Fast Fading Margin=3dB

Slowly Fading Margin=5dBInterference margin=4dB

? dBmOutdoor

Sms=-102dBm


Slowly Fading Margin=5dB

Interference margin=4dB

Penetration Loss=10

? dBmResident area, indoor

Sms=-102dBm




Penetration Loss=18

? dBmDensity urban, indoor

GivenMin. Receiving LevelApplication Environment



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Min. Receive Level

Sms=-102dBm


Slowly Fading Margin=5dBInterference margin=4dB

-90dBmOutdoor

Sms=-102dBm




Penetration Loss=10

-80dBmResident area, indoor

Sms=-102dBm




Penetration Loss=18

-70dBmDensity urban, indoor

GivenMin. Receiving LevelApplication Environment



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Link Budget

receivemsbtscablecombinerbts MinGLGLLP ++

receivecablebtsdiversitymsmsMinLGGLGP +++

GSM has two frequency bands: 900 MHz and 1800 MHz. Each band has

different transmission characteristics. Long wavelength comes with little diffraction

loss and short wavelength comes with little building penetration loss. Indoor wave

component is the superimposition of penetration component and diffraction

component. Diffraction component constitutes most of the wave component, and

therefore, the indoor and outdoor level difference of 1800 MHz is greater than that

of 900 MHz. Because of the issues such as complex transmission environment and

the direction of incident waves, quantify indoor and outdoor level difference is not

very practical. The best way is to carry out level difference test in special

environment for planning optimization.



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Link Budget Model

receivemsbtscablecombinerbts MinGLGLLP ++

receivecablebtsdiversitymsmsMinLGGLGP +++

On downlink

On uplink



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Equipment-related Parameters BTS Tx power

Maximum BS Tx power. Maximum power of the antennaPtrx-Lcdu

Maximum MS Tx power

900:2W

1800:1W

BS antenna gain

Typical value: Omni directional antenna: 11dBi or 13dBi;

directional antenna: 15 to 18dBi.

MS antenna gain

Generally, MS antenna and the connection loss areconsidered to be 0dB.



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Equipment-related Parameters

BTS receiver sensitivity -112.5dBm

The sensitivity is also related with vendor and environment

MS receiver sensitivity

-102dBm



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No Combining

TCOM

TRX0TRX0

TX

TRX1TRX1

TX

TX1

IN1

IN2

TX2

RXM1

RXD1

RXM2

RXD2

combinercombiner

For the cell which just has one or two TRX, the TRX will not be connected to the

combiner and directly connected to DDPU (Dual Duplexer Unit for DTRU BTS). So it is

combiner loss will be 0---1 dB.

The DDPU is for sending multi RF signals from the transceiver in the DTRU to the antenna

through the duplexer

Sending signals from the antenna after amplifying and quartering them to the transceiver in

the DTRU



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Wide Band Combining

TRX0TRX0

TX

TRX1TRX1

TX

TX1

IN1

TCOM

IN2

TX2

combinercombiner

If for the cell which has more than two TRX, TRX0 and TRX1 will be connected to

the combiner first and then connected to DDPU. It s combiner

loss will be 3.3+1=4.3dB

The DDPU is intermixed with the DCOM (Combining Unit for DTRU BTS in the

DAFU subrack of the forepart of RF subsystem. It is indispensable. Generally, the number

of DDPU is one at least and three at most. Without the DCOM, there can be at most six

DDPUs

Sending multi RF signals from the transceiver in the DTRU to the antenna through the

duplexer

Sending signals from the antenna after amplifying and quartering them to the transceiver in

the DTRU

The DCOM is optional and there are a maximum three DCOMs. The DTRU

combines two carriers into one channel. The DCOM is required when the DTRUs

are insufficent

The DCOM combines the 2-route DTRU transmission signals and outputs them to

the DDPU



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Feeder and Jumper

feederconnector

Feeder

Antenna Adjustable Support

GSM/CDMA

Panel Antenna

BTS

Wall

jumper

In a wireless telecommunication system, the antenna provides the interface between base

transceiver station (BTS) and outside propagation mediums. One set of antenna can both

radiate and receive radio waves. When radiating radio waves, it converts high frequency

current into electromagnetic wave; when receiving radio waves, it converts the

electromagnetic wave into high frequency current.

During network planning, the right antenna is selected according to the radio environment

of the BTS. The parameters, such as antenna height, antenna azimuth angle, tilt angle, are

decided based on the selected antenna.

Antenna is directly related to uplink and downlink converges, so are the radio frequency

(RF) components, such as feeder cable, combiner, and duplexer.



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Antenna Feeder SystemFeeder

Feeder:

Frequently-used specification:

7/8 ", 5/4 "

The curvature of the feeders shall not be

too large, and the conductor surface is

required to well connected with the ground

80 meters

900MHZ


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Coverage Probability

area coverage probability: Within a coverage area, the percentage

of area in which receive signal strength (RxLev) is always higher than

RxLev threshold

edge coverage probability: In coverage board area, the percentage

time when the receive signal strength (RxLev) is always larger than

the of RxLev threshold

Sometimes during the planning, coverage probability also have to consider. And for

high coverage probability, high shadow fading margin reserved. Normally, there are

two types coverage probabilities: area coverage probability and edge coverage

probability.

According to the standard deviation of the shadow fading and the requirements for

the border coverage probability (determined by the operator), we can calculate the

edge coverage probability by formula.



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Margin

To ensure a certain edge coverage probability , it is

necessary to reserve some power margin, i.e. the shadow

fading margin.

Due to the shadow fading, the actual path loss fluctuates

around this value. It is subjected to the logarithmic normal

distribution as the location and time varies.

Note : the 75% edge coverage probability is corresponding to the 90% area

coverage probability.

Concept of communication probability: Success call rate of MS on the

radio coverage border or in the cell

Category of communication probability: location probability and time

probability

In general, the time change has little impact on the communication

probability, so it can be neglected.



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Area coverage probability to expected

shadow fading margin

50% 60% 75% 80% 90% 92% 93% 95% 97% 98% 99% 100%

Dense Urban -6.7 -4.2 -0.1 1.4 5.5 6.5 7.2 8.6 10.7 12.2 14.6 21.3

Urban -6.7 -4.2 -0.1 1.4 5.5 6.5 7.2 8.6 10.7 12.2 14.6 21.3

SubUrban -6.7 -4.2 -0.1 1.4 5.5 6.5 7.2 8.6 10.7 12.2 14.6 21.3

Rural Area -6.6 -4.3 -0.6 0.8 4.3 5.4 5.9 7.2 9.1 10.4 12.3 19.2

High Way -6.1 -4.4 -1.8 0 1.4 2 2.4 3.2 4.3 5.1 6.5 10.4



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Min. Receiving Level

On Down Link

On Uplink

marginfadingshadowarg

argarg

+++

++=

npenetratioinm

inminmmsreceive

LFastFading

ngSlowlyFadiISMin

marginfadingshadow

argargarg

++

+++=

npenetratio

inminminmbtsreceive

L

FastFadingngSlowlyFadiISMin



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Example

30MS max. transmitting power(dBm)

-102MS sensitivity (dBm)

?Effective Radiated Power EIRP(dBm)

17BTS antenna gain (dBi)

?BTS combiner, jumper, feeder and connectorloss (dB)

0.5feeder connector loss (dB)

11dB/100m51/2 jumper length (m)

4dB/100m457/8 feeder length (m)

1BTS combiner loss (dB)

46BTS max. transmitting power (dBm)



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Example

?dBexpected shadow fading margin (dB)

2Noise correction (dB) (interference margin)

2dBclutter loss (dB) (slow fading margin)

1dBFast fading margin

1dBMS antenna gain

?allowed DL Max Propagation loss in Um interface(dB)

4Body loss (penetration loss)

91%corresponding edge coverage probability

97%expected area coverage probability



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Site Coverage Radius: R

Site distance: D=1.5RCoverage Area=1.949R2

Site Coverage Radius: R

Site distance: D=1.732RCoverage Area=2.598R2

3 Sectors site Omni site

Distance and Coverage Area



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Example

?Expected BTS number

?Cell dimenstionkm2

0.80Cell radiuskm

OmniSite type

500Expected coverage area

dimensionkm2



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Link Balance Tool

link balance



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Contents

1. Planning Basis


3. Advance Planning




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Why Indoors

Indoor coverage become the main competition between operators

Subscribers expect continuous coverage and better quality

Outdoor cell cant provide sufficient indoor coverage

INDOOR SOLUTION

GoodQuality!

With the rapid development of economy, hotels, commercial centers, large-

scale flats, underground railways, and underground parking areas are arising

by batch. As a result, mobile stations are more frequently used in indoor

environment. Thus, they require better indoor mobile communication services.

Generally, the following problems are present in indoor mobile

communication systems:

From the perspective of coverage, the complex indoor structure and the

shielding and absorbing effect of the buildings cause great radio wave

transmission loss. As a result, the signals in some areas may be weak,

especially the signals in the first and second floors in the underground are

quite weak, or even there are dead zones. In this case, mobile stations cannot

necessarily access the network, there is no paging response, or subscribers are

not in service areas.

From the perspective of network quality, the factors interfering radio

frequencies are probably present in upper floors of high buildings. In this case,

the signals in service areas are not stable, so ping pong effect may occur and

conversation quality cannot be ensured.

From the perspective of network capacity, if mobile stations are frequently

used in buildings, such as large-scale shopping centers, conference halls,

some areas in the network cannot meet the requirements of subscribers. In

this case, congestion may occur on radio channels.PDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com


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Building Penetration Loss

rear side :-18 ...-30 dB

Pref = 0 dB

Pindoor = -3 ...-15 dB

Pindoor = -7 ...-18 dB

-15 ...-25 dB no coverage

signal level increases with floornumber :~1.5 dB/floor (for 1st..10th floor)

Signal level in building is estimated by using a building penetration loss

margin

Big differences between rooms with window and without window(10~15 dB)



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Building Penetration Loss

Signal loss for penetration varies betweendifferent building materials, e.g.:

mean value

reinforced concrete wall, windows 17 dB

concrete wall, no windows 30 dB

concrete wall within building 10 dB

brick wall 9 dB

armed glass 8 dB

wood or plaster wall 6 dB

window glass 2 dB



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Indoor Coverage Solutions

Small BTS

Mini BTS

Repeater

Active

Passive

Optical

Antennas

Distribute antenna

Leaky cable

Signal distribution

Power splitter

Optical fiber



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Indoor Planning

Example2:1.2 MHz allocation

50 mErl/subscriber , GOS=2%reuse per two floor, separatefrequencies within one floor:a) three floors

52.12 Erl => 842subs

b) ten floors140 Erl => 2808 subs

Example1:1.2 MHz allocation

50 mErl/subscriber, GOS=2%no frequency reuse:

a) three floors

34.68 Erl=> 694 subscribers

b) ten floors34.68 Erl => 694 subscribers

Single cell approach Multi-Cell approach

t

f5

f6

f5

f1

f2

f1

f3

f4

f3f1..f6

f1..f6

f1..f6



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Indoor Coverage Examples

With Repeater

Relay outdoor signal into target building

Need donor cell, add coverage but not capacity

With indoor BTS and distributed antenna

Heavy loss bring by power splitting and cable

1:1

50m

50m

1:1

50m

50m

1:1

50m

50m

1:1

50m

50m

1:1

50m

50m

1:1

1:1:1

1:1

4th floor

3rd floor

2nd floor

1st floor

ground floor

Outdoor Antenna

Gain: 18 dBi

Indoor Antenna

Gain: 9dBi

Target Indoor Coverage Building

7/8'' Cable

Loss: 4dB / 50m

Cable length : 25m

-50 dBm

4th Floor

3rd Floor

1st Floor

Ground Floor

2nd Floor



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Repeater Application examples

Coverage for low traffic area Remote valley

Tunnel

Underground coverage

needs

decoupling > amplification



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Wave Propagation in Tunnels

The tunnel types include railway tunnel (or metro tunnel), highway

tunnel.

Highway tunnel is wide, select the antennas with a larger size to

obtain a higher gain, coverage distance is larger.

Railway tunnel is narrow, the antenna size and gain are greatly

restricted. Especially the radio propagation is greatly affected by

passing train.

The tunnel types include railway tunnel, highroad tunnel, and underground

railway tunnel. Each tunnel has its characteristics, and they are specified as

follows.

For the highroad tunnel, it is wide. The coverage in the highroad tunnels is

relatively stable. When there are vehicles passing by, you can select the

antennas with a larger size to obtain a higher gain, so the coverage distance is

larger.

For the railway tunnel, it is narrow, especially when there is a train passing

by; only a little room is left in the tunnel, so the radio propagation is greatly

affected. Moreover, the train has great effect on radio signals. Since the

antenna installation room is quite limited, the antenna size and gain are

greatly restricted. In addition, because general cars cannot be driven to such

tunnels, the tunnel coverage is hard to be tested. Therefore, the planning forhighroad coverage is different from that of the railway coverage.



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Short and Middle Tunnels Coverage

Generally, the tunnels shorter than 100m are defined as short

tunnels. l the antenna can be installed at the tunnel entrance so as

to ensure coverage.

For the tunnels shorter than 500m, can use the combination of a

micro base station and a single antenna (or a repeater) for the

tunnel coverage, and install the antenna in the middle of the

tunnel.



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Long Tunnels Coverage

For the tunnels longer than 500m, you need to use the distributed

antenna system or the leaky cable for the coverage.

For the coverage of still longer tunnels, use amplifiers to amplify

signals. That is, you can use either the distributed antenna system

or the leaky cable for the coverage solution. In terms of technical

indexes and installation space, coverage solution based on leaky

cable is recommended.



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Tunnels Coverage

If outside tunnel and within the tunnel belong to the difference cell,

handover problem will occur. To solve this problem, can consider

adopting the following methods:

Adopt the bi-directional antenna for the tunnel coverage, because

it can provide enough overlapping area for handover.

Enable special handover algorithms, such as fast level fall

handover algorithm. In this case, a mobile station can hand over

to another cell when the signal level falls fast.

Select the directional antenna with small front-to-back ratio.



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Contents

1. Planning Basis


3. Advance Planning

4. Advance Technology for improving



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Transmitting diversity

TDMA

Frame

Delayed

TDMAFrame

TDMAFrame

1~2 Symbols

TRXB

TRXA

Two transciver transmit the same information by the same output power as

single TRX in the different time, the MS equalizer can combine the two

signal just like deal with the multipath signal.

The two downlink path transmitter signal have some time delay even if we use double

polarization antenna, the MS also can combined the two signal in the equalizer.

Improve the downlink BCCH TRX downlink performance

Improve the downlink TCH TRX downlink performance in RF hopping or No RF hopping

Especial for stationary and slowly moving MS



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Two TRXs transmit the same signal with 7.4us time

delay.

Improving downlink coverage based on mutualexchange theory.

Generally 3dB downlink gain from transmittingdiversity.


TRXA

TRXB

Two TRX transmit the same signal with 7.4us delay between. Generally 3dB downlink gain

out of transmitting diversity



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PBT(Power Booster Technology)

Adopt the in-phase synthesizing technology. Generally PBT can generate 2dB downlink gain.

PA

RF

PA

Synthesizer

DUPLEX

RF

BB



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Dynamic PBT

This technology is based on timeslots, allows a calling subscriber

to use a timeslot in other TRX.

When the receive level is lower , channels corresponding to

identical timeslots in adjacent carriers stop delivering services

temporarily.

At this time, the RF channel in the service timeslot and the

auxiliary channel in the adjacent carrier transmit identical signals,

whose phase is also the same. The combined signals are stronger,

thus improving the receiving quality for the subscriber.

This technology is based on timeslots, allows a calling subscriber to use a timeslot in

other TRX. A measuring report is used to monitor this subscriber s downlink receive

level. When the receive level is lower than the preset threshold, Channels

corresponding to identical timeslots in adjacent carriers stop delivering services

temporarily. The related RF channel provides PBT as an auxiliary channel. At this

time, the RF channel in the service timeslot and the auxiliary channel in the adjacent

carrier transmit identical signals, whose phase is also the same. The combined signals

are stronger, thus improving the receiving quality for the subscriber.



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PBT(Power Booster Technology)



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4-way receiving diversity

Compared with 2-way receiving diversity, 4-way

receiving diversity gets more 3~5dB uplink gain.

RF1

RF2

RF3

RF4

BB

>120%R

2WRD

4WRD

R



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TCH/AHS4.75

TCH/AHS5.15

TCH/AHS5.9

TCH/AHS6.7

TCH/AHS7.4

TCH/AHS7.95

AMR-HR

Experiment 1b - Test Results

1.0

2.0

3.0

4.0

5.0

Conditions

M OS

Sel. Requir.

AMR-HR

EFR

FR

HR

Sel. Requir. 3.99 3.99 3.99 3.14 2.74 1.50

AMR-HR 4.11 4.04 3.96 3.72 3.38 3.10 2.00

EFR 4.21 4.21 3.74 3.34 1.58

FR 3.50 3.50 3.14 2.74 1.50

HR 3.35 3.24 2.80 1.92

No Errors C/I=19 dB C/I=16 dB C/I=13 dB C/I=10 dB C/I= 7 dB C/I= 4 dB

AMR

High voice quality than HR and good customer experience.

Low C/I requirement and easy to network planning.

More robust than HR and stronger anti-interference.

Increase 80%~140% network capacity and decrease CAPEX of network.



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Gain of Advance Technology

3~5dB(uplink)4-way receiving diversity

5dB(when EFR lower than

5%,compare with FR)

AMR

2dBPBT

3dBTransmitting diversity

Gain



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The Function of Extended Cell

In the GSM specifications, the cell coverage is restricted within 35km(63

TA) . Thus, the coverage radius of the cell cannot exceed 35km. In wide

and open area where the subscribers are dispersedly distributed, the

traffic is low, and the infrastructure such as transmission and power

supply facilities is hard to construct or cannot reach, the cell with a radius

larger than 35km must be provided.

If the extended cell technology is adopted, the cell coverage radius can

reach 120km in an ideal condition. Operators can adopt this technology to

reduce the number of sites and build their own GSM networks quickly

with smaller investment. In this way, they can attract mobile subscribers

in special areas and thus increase the operation revenue.



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Transmission delay t

Transmission delay t

TA

The mobile phone should

send the signal in advance!!

Timing Advance (TA)

Transmission delay is unavoidable in the radio interface. If the mobile station

moves away from the base station during a call, the further distance the more delay.

The uplink is as the same.

If the delay is too high, the timeslots of the signal from a certain mobile station

and that of the next signal from another mobile station received by the base stationwill overlap each other, thus causing inter-code interference. To avoid this, during a

call, the measurement report sent from the mobile station to the base station carries a

delay value. Moreover, the base station should monitor the time when the call arrives

and send an instruction to the mobile station via the downlink channel every 480ms

so as to inform the mobile station the time of advance transmission. This time is the

TA (timing advance), which ranges between 0~63 (0~233s ). The TA value is

limited by the timing advance code 0~63bit of the GSM system. Therefore, the

maximum coverage distance of the GSM is 35km. Its calculation is as follows:

1/2*3.7 s /bit*63bit*c=35km

{In the formula, 3.7s /bit is the duration per bit (156/577); 63bit is the

maximum bit number of the time adjustment; c is the light speed (transmission speed

of the signal); and indicates that the go and return trip of the signal.}

According to the above description, the distance corresponding to 1bit period is

554m. Influenced by the multi-path propagation and MS synchronization precision,

the TA error may reach up to about 3bit (1.6km).



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Dual Timeslot Extended Cell

Delay63

Modulation range

Normal cell

Dual timeslot extended cell



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To support MS signals with a delay exceeding 63bit, the 2-

timeslot cell can bind the even and odd timeslots, as if a

TDMA frame in the extended cell only has four channels:

0/1, 2/3, 4/5, and 6/7. Only channel 0, 2, 4, and 6 can be

assigned for the MS.

B0 B2 B3B1 B4 B5 B6 B7

0/1 2/3 4/5 6/7



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The dual-timeslot function is based on the concentric cell. The carrier in

the underlay cell is configured as the 2-timeslot carrier. The carrier on the

overlay cell is configured as a common cell. When the cell is configured

as a 2-timeslot cell, the concentric cell attribute of this cell is automatically

set to the concentric cell.

If all carriers in the cell must be configured as 2-timeslot carrier, such

solution is called the cell-level 2-timeslot solution. In this case, all carriers

are configured in the overlay cell.

If some carriers in the cell are configured as common carriers and others

as 2-timeslot carriers, the BCCH is located on the 2-timeslot carriers,

such solution is called carrier-level 2-timeslot solution. In this case, the 2-

timeslot carriers are configured in the underlaid cell and the common

carriers are configured in the overlaid cell.



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Question

What is the max value of extended cells TA?

Max TA?Max TA?



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Assignment of Extended Cell

UnderlaidIn-coming BSC HO

UnderlaidIntra-BSC HO

Depend on assign optimum layerAssignment

UnderlaidImm-assignment

Assignment StrategyType



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Configuration

Modify the cell as double timeslot extended cell.



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Configuration

Configure the TRX as overlaid or underlaid.



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Summary

In this course, we have learned:

Propagation and planning basis

Coverage planning method

Indoor and tunnel planning

Planning procedure and site location

coverage planning course

Documents