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etwork Dimensioning


EXPLAIN CHAPTER 4

Dimensioning

Coverage Planning

Capacity Planning


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etwork Dimensioning

Dimensioning

EXPLAIN paragraph 4.1

Dimensioning (3)

Input data (4)


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etwork Dimensioning

DimensioningKey Quantities

Key quantities for radio network

dimensioning # of BS needed for coverage reasons

(par. 4.2) # of BS needed for capacity reasons

(par. 4.3)

outage probabilities/percentages frequency re-use rate (vs.interference)

bandwidth used

Design goals are inter-dependant network can only be optimised with

respect to one single aspectDe

sign goals to be applied must beclearly agreed with customer!


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etwork Dimensioning

DimensioningLimiting factors

Before T0, the network is coverage limited

After T0, the network is capacity limited

The other constraint is automaticallyfulfilled

# of BS

time

coverage

capacity

T0

At the very beginning, just thecoverage planning is needed


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etwork Dimensioning

DimensioningNetwork Expansion

When the network is coverage

limited, the expansion consists of: adding new sites in not already

covered areas

When the network is capacitylimited, the expansion consists of:

adding TRXs; adding new sites in already covered

areas; adding software capacity...

cap. 7


7/44EXPLAIN v3.0 - Nokia 2001 DVassena

Network DimensioningNetwork Dimensioning

Input DataPreliminary Questions

Main purpose of the network?

1st operator in country plain coverage? 2nd operator competitive pricing? 3rd operator replacing wire line phones?

Roamer volumes expected?

Where?

Neighbouring countries

existing international regulations?

Use of microwave links for transmission?

Each network philosophycalls for a different planningapproach




Input DataMorpho data

Maps main cities

important roads

location ofmountain ranges

inhabited area

shore lines

Localknowledge

city skylines

typicalarchitecture

structure of city

local habits




Input DataDemographic Data

Statistical

yearbook largest towns, cities

population distribution

where are expectedcustomers?

Local knowledge

population migrationroutes

commuting trafficvolumes

subscriberconcentration points

2 mill.pop.

300 000 pop.

400 000 pop.

400 000 pop.

250 000 pop.




Roll-out phases &

time schedules Coverage level

requirements

Indoor coverageareas

MS classes to planfor

Operators celldeploymentstrategies

omni-cells in rural

areas?3-sector cells inurban areas?

minimum of 2 TRXper cell?

phase 1NW launch

rollout

phase 2

rollout

phase 3

Input DataCoverage Requirements

k i i i




Coverage Planning

EXPLAIN paragraph 4.2

Power budget (8)

Cell size (12)

N

t k Di i i




Power BudgetBasics

Power budget is used to calculate

the maximum allowed path loss Main factors depend on

equipment characteristics BTS & MS TX power BTS & MS RX sensitivity

Other factors can be classified into3 categories and have to beestimated

loss factors

gain factors margins

N

t k Di i i




~ 3 5 dB losses50 70% of

signal power is lostbefore even

reaching the TXantenna

Power BudgetLoss Factors

At BS side connectors cables isolator combiner filter

At MS side body loss polarisation ofantenna

manym

eters

cables &connectors

filter

combiner

BS output

N

t k Di i i




Power BudgetGain Factors

Antenna gain main antenna parameter slight difference between DL and UL the antenna models in use should be

defined at the very beginning of theproject

Diversity gain diversity can be implemented in manyways, with different gains

Frequency hopping gain FH improves average link quality, but

it isnt taken into account in powerbudget calculations

No gain factors at MS side

N

et ork Dimensioning


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Power BudgetMargins

Fast fading margin

Fast variations in field strength levelsthat are caused by multipath receptionhas to be taken into account incalculating the maximum allowed pathloss

Slow fading margin

Slow fading that is caused byshadowing has a direct effect on the

location probability; this has to betaken into account in evaluating cellsize

Penetration losses

Fo

rpowerbu

dget

ca

lculations

Forcellsizeevaluatio

ns

N

etwork Dimensioning


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WLL subscribers

path loss = 154 dB

combinerloss = 5dB

FeederLoss = 4 dB

Rx Sensitivity- 102 dBm

Tx Power45 dBm (20W)

Antenna

Gain = 16dBi

- 102 dBm

52 dBm

36 dBm

40 dBm

Power BudgetDown-Link

N

etwork Dimensioning


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WLL subscribers

path loss = 154 dBFeeder

Loss = 4 dB

Tx Power33 dBm (2W)

AntennaGain = 16 dBi

DiversityGain = 4 dB

33 dBm

- 121 dBm

- 101 dBm

- 105 dBm

Rx Sensitivity-105 dB

Power BudgetUp-Link

N

etwork Dimensioning


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Power BudgetExample

Power budget

GENERAL INFORMATION

Frequency ( 1800 System: DCS1800

Case descri MS Class: 1

RECEIVING END: BS MS

RX RF- Input Sensitivity dBm -108.00 -100.00 A

Interference Degradation Margin dB 3.00 3.00 B

Body Proximity Loss dB 0.00 2.00 C

Cable Loss +Connectors dB 3.00 0.00 D

Rx Antenna Gain dBi 18.00 0.00 E

Diversity Gain dB 4.00 0.00 F

Isotropic Power dBm -124.00 -95.00 G=A+B+C+D-E-F

Field Strength dBV/m 18.31 47.31 H=G+Z*

TRANSMITTING END: MS BS

TX RF Output Peak Power W 1.00 29.50

(mean power over RF cycle) dBm 30.00 44.70 K

Body Proximity Loss dB 2.00 0.00 L

Isolator +Combiner +Filter dB 0.00 2.20 M

RF-Peak Power, Combiner Output dBm 28.00 42.50 N=K-L-M

Cable Loss +Connectors dB 0.00 3.00 O

TX Antenna Gain dBi 0.00 18.00 P

Peak EIRP W 0.63 562.11

(EIRP =ERP +2dB) dBm 28.00 57.50 Q=N-O+P

* Z=77.2 +20*log(freq[MHz])LINK-BALANCE EVALUATION UL DL

Theoretic Isotropic Path Loss dB 152.00 152.50 R=Q-G

Isotropic Path Loss to be considered dB 152.00 UL Limited Min (UL,DL)

Path Loss unbalancement dB 0.50 Abs (UL-DL)

TX RF Max Output Power to be used dBm 30.00 44.20

BT99 - AFE with combiner bypass (equiv. to

1 2

3

4

N

etwork Dimensioning


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Power BudgetConclusions

Power budget has to be balanced, even if

the BTS has higher TX power than the MS diversity gain is for UL only

BTS RX sensitivity is better than for the MS

The maximum allowed path loss is usuallyUL limited

There are as many power budgets asdifferent site configurations are defined,even into the same project

the site configurations in use should be definedat the very beginning of the project

k i i iN

etwork Dimensioning


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Cell SizeBasics

Based on the calculated maximumallowed path loss, the cell size canbe evaluated

This is done by using

location probability values coverage thresholds

basic propagation prediction formulas

Okumura-Hata

Walfish-Ikegami

N t k Di i iN

etwork Dimensioning


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Real maximumallowed path loss

Cell SizeProcess

EIRP -

(Maximum allowedpath loss

Slow fading margin

Building penetrationloss)

=

Coverage threshold

Cell radius

Cell area

function (location probability)

From power budget calculations

function (morphological area)

Okumura-Hata

function (morphological area)

N t k Di i iN

etwork Dimensioning


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Full coverage of an area can neverbe guaranteed!

Cell SizeLocation Probability

Outages

due to coverage gaps Pno_cov due to interferences Pif

Total location probability in a cell

(1- Pno_cov ) * (1- Pif)

Both time and location probability

Typical required values are 90-95%

N t k Di i iN

etwork Dimensioning


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When calculating cell radius, LP is

50% by the cell edge and ~75%over the cell area

To get 90% LP, the cell radius hasto be reduced

Cell SizeSlow Fading Margin

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

-3 -2 -1 0 1 2 3

90% ofthe area

Slow fading margin


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etwork Dimensioning


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Cell SizeCoverage Thresholds


etwork Dimensioning


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COMMON INFO DU U SU F O

MS antenna height (m): 1,5 1,5 1,5 1,5 1,5

BS antenna height (m): 30,0 30,0 30,0 45,0 45,0

Standard Deviation (dB): 7,0 7,0 7,0 7,0 7,0

BPL Average (dB): 15,0 12,0 10,0 6,0 6,0

Standard Deviation indoors (dB): 10,0 10,0 10,0 10,0 10,0

OKUMURA-HATA (OH) DU U SU F O

Area Type Correction (dB) 0,0 -4,0 -6,0 -10,0 -15,0

WALFISH-IKEGAMI (WI) DU U SU F O

Roads width (m): 30,0 30,0 30,0 30,0 30,0

Road orientation angle (degrees): 90,0 90,0 90,0 90,0 90,0

Building separation (m): 40,0 40,0 40,0 40,0 40,0

Buildings average height (m): 30,0 30,0 30,0 30,0 30,0

INDOOR COVERAGE DU U SU F O

Propagation Model OH OH OH OH OH

Slow Fading Margin + BPL (dB): 22,8 19,8 17,8 13,8 13,8

Coverage Threshold (dBV/m): 59,1 56,1 54,1 50,1 50,1

Coverage Threshold (dBm): -77,2 -80,2 -82,2 -86,2 -86,2

Location Probability over Cell Area(L%): 90,0% 90,0% 90,0% 90,0% 90,0%

Cell Range (km): 1,33 2,10 2,72 5,70 7,99

OUTDOOR COVERAGE DU U SU F O

Propagation Model OH OH OH OH OH

Slow Fading Margin (dB): 4,5 4,5 4,5 4,5 4,5

Coverage Threshold (dBV/m): 40,8 40,8 40,8 40,8 40,8

Coverage Threshold (dBm): -95,5 -95,5 -95,5 -95,5 -95,5

Location Probability over Cell Area(L%): 90,0% 90,0% 90,0% 90,0% 90,0%

Cell Range (km): 4,39 5,70 6,50 10,69 14,99

Cell SizeExample


etwork Dimensioning


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Network Dimensioningg

After cell radius has been

determined, cell area can becalculated

When calculating cell area,traditional hexagonal model is

taken into account

R

OmniA = 2,6 R1

2Bi-sector

A= 1,73 R22

Tri-sector

A = 1,95 R32

R

R

Cell SizeCell Area


etwork Dimensioning


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Cell SizeCell Area Terms

Dominance

area Service area

Coverage area

6dB hysteresismargin

coverage limit

cell coverage range

cell service range

dominance range


etwork Dimensioning


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Three hexagons Three cells

Cell SizeHexagons vs. Cells


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Cell SizeEnhancement

Improving link budget

sensitivity power antennas

Reducing the effect of geography

BTS antenna heights good network plan

Technical solutions for improvinglink budget

combiner by-pass

mast head preamplifier booster


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etwork Dimensioning


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Capacity PlanningEXPLAIN paragraph 4.3

Traffic (2)

Trunking (3)

Erlang (3)

Cell Capacity (4)


etwork Dimensioning

T ffi


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TrafficTraffic Estimations

Estimate number of subscribers over

time long-term predictions numbers available from marketing people?

Expected traffic load per subscriber different subscriber segments? expected behaviour of user segments

Particular phone habits of subscribers e.g. mainly heavy indoor usage phoning while in traffic jams?

Busy hour conditions time of day

traffic patterns


etwork Dimensioning

T ffi


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TrafficTraffic Patterns

Traffic is not evenly spread across the

day(or week)

Dimensioning must be able to copewith peak loads

busy hour is typically twice the

average hour load

0

10203040

5060708090

100

0 2 4 6 8 10 12 14 16 18 20 22 24hr

%peak timeoff-peak


etwork Dimensioning

T ki


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M potential customers

m available resourcesM >> m

Problem: many customers, limited

number of resources How many resources do we need

to satisfy the demand?

TrunkingBasics


etwork Dimensioning

T ki


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g

TrunkingTrunking Effect

Trunking increases effective usage

of limited resources when we increase the traffic, we may

not need that many new lines

Main parameter: acceptedblocking probability

Blocking depends on number of available resources traffic statistical distribution


etwork Dimensioning

T ki


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g

time

CH 1

CH 2

CH 3

CH 4

CH ...

CH 5

CH n-2

CH n-1

CH n

Offered newtraffic

TrunkingTrunking Effect


etwork Dimensioning

E l


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g

ErlangDefinition

Erlang is the unit of traffic

definition

2 formulas Erlang B: for systems that

support no queuing Erlang C: for systems that

support queuing

Seconds3600

)()(Erlangs

timeonconversatiaveragehourpercallsx

=

Agner Krarup Erlang (1878-1929)


etwork Dimensioning

E l


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g

ErlangErlang Formulas

Erlang B

no queuing:blocked calls aredropped depends oncall lengths &statistical

distribution ofcalls applicable inmobile systems(e.g. airinterface)

Erlang C

queuing applicable intrunkingsystems

pk =

k

/ k !

i=0

M

[ i

/ i ! ]

=

+=>

1

0 !1!

)0(Pr C

k

kC

C

k

A

C

ACA

A

delayob


etwork Dimensioning

E l


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B lo c k in g P ro b a b ility B lo c k in g P ro b a b ility

C h a n n e ls 1 % 2 % 3 % 5 % C h a n n e ls 1 % 2 % 3 % 5 %

1 0 , 0 1 0 , 0 2 0 , 0 3 0 , 0 5 2 1 1 2 , 8 0 1 4 , 0 0 1 4 , 9 0 1 6 , 2 0

2 0 , 1 5 0 , 2 2 0 , 2 8 0 , 3 8 2 2 1 3 , 7 0 1 4 , 9 0 1 5 , 8 0 1 7 , 1 0

3 0 , 4 6 0 , 6 0 0 , 7 2 0 , 9 0 2 3 1 4 , 5 0 1 5 , 8 0 1 6 , 7 0 1 8 , 1 0

4 0 , 8 7 1 , 0 9 1 , 2 6 1 , 5 2 2 4 1 5 , 3 0 1 6 , 6 0 1 7 , 6 0 1 9 , 0 0

5 1 , 3 6 1 , 6 6 1 , 8 8 2 , 2 2 2 5 1 6 , 1 0 1 7 , 5 0 1 8 , 5 0 2 0 , 0 0

6 1 , 9 1 2 , 2 8 2 , 5 4 2 , 9 6 2 6 1 7 , 0 0 1 8 , 4 0 1 9 , 4 0 2 0 , 9 0

7 2 , 5 0 2 , 9 5 3 , 2 5 3 , 7 5 2 7 1 7 , 8 0 1 9 , 3 0 2 0 , 3 0 2 1 , 9 08 3 , 1 3 3 , 6 3 3 , 9 9 4 , 5 4 2 8 1 8 , 6 0 2 0 , 2 0 2 1 , 2 0 2 2 , 9 0

9 3 , 7 8 4 , 3 4 4 , 7 5 5 , 3 7 2 9 1 9 , 5 0 2 1 , 0 0 2 2 , 1 0 2 3 , 8 0

1 0 4 , 4 6 5 , 0 8 5 , 5 3 6 , 2 2 3 0 2 0 , 3 0 2 1 , 9 0 2 3 , 1 0 2 4 , 8 0

1 1 5 , 1 6 5 , 8 4 6 , 3 3 7 , 0 8 3 1 2 1 , 2 0 2 2 , 8 0 2 4 , 0 0 2 5 , 8 0

1 2 5 , 8 8 6 , 6 1 7 , 1 4 7 , 9 5 3 2 2 2 , 0 0 2 3 , 7 0 2 4 , 9 0 2 6 , 7 0

1 3 6 , 6 1 7 , 4 0 7 , 9 7 8 , 8 3 3 3 2 2 , 9 0 2 4 , 6 0 2 5 , 8 0 2 7 , 7 0

1 4 7 , 3 5 8 , 2 0 8 , 8 0 9 , 7 3 3 4 2 3 , 8 0 2 5 , 5 0 2 6 , 8 0 2 8 , 7 01 5 8 , 1 1 9 , 0 1 9 , 6 5 1 0 , 6 0 3 5 2 4 , 6 0 2 6 , 4 0 2 7 , 7 0 2 9 , 7 0

1 6 8 , 8 8 9 , 8 3 1 0 , 5 0 1 1 , 5 0 3 6 2 5 , 5 0 2 7 , 3 0 2 8 , 6 0 3 0 , 7 0

1 7 9 , 6 5 1 0 , 7 0 1 1 , 4 0 1 2 , 5 0 3 7 2 6 , 4 0 2 8 , 3 0 2 9 , 6 0 3 1 , 6 0

1 8 1 0 , 4 0 1 1 , 5 0 1 2 , 2 0 1 3 , 4 0 3 8 2 7 , 3 0 2 9 , 2 0 3 0 , 5 0 3 2 , 6 0

1 9 1 1 , 2 0 1 2 , 3 0 1 3 , 1 0 1 4 , 3 0 3 9 2 8 , 1 0 3 0 , 1 0 3 1 , 5 0 3 3 , 6 0

2 0 1 2 , 0 0 1 3 , 2 0 1 4 , 0 0 1 5 , 2 0 4 0 2 9 , 0 0 3 1 , 0 0 3 2 , 4 0 3 4 , 6 0

ErlangErlang B Table


etwork Dimensioning

C ll C it


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Cell CapacityTraffic

Traffic capacity of a cell is determined by

the number of available traffic timeslots Trunking effect gives significant gains

TRX 1 1 2 3 4 5 6 7BCCH + CCCH 0,5 0,5 0,5 0,5 0,5 0,5 1 1SDCCH 1,5 0,5 1,5 1,5 2,5 2,5 3 3TCH 6 7 14 22 29 37 44 52Erl (2% blocking)2,27 2,93 8,20 14,89 21,04 28,25 34,68 42,12

TCH

SDCCH

BCCH/CCCH


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Cell Capacit


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Mainly realised by Stand-alone

Dedicated Control CHannel(SDCCH)

SDCCH is mainly used in 5 cases: call set-up SMS

location updates emergency call call re-establishment

SDCCH channel is key in achievingsuccessful & efficient call set-up

Cell CapacitySignalling


etwork Dimensioning

Cell Capacity


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Cell CapacitySDCCH Configurations

TS0of BCCH TRX always for BCCH

+ CCCHTS

0may be configured to carry

DCCH

SDCCH channels may beconfigured in any other TS.Convention (but not law!) is to putit on TS1

2 basic configurations

combined non-combined

Combined configuration

0 7

ts0=bcch/sdcch/4/pch/agch

Non-combined configuration

0 7

ts0=bcch/pch/agchts1=sdcch/8


etwork Dimensioning

Cell Capacity


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Cell CapacitySDCCH Dimensioning

Efficient network design is

required to achieve 2 goals an appropriate signallingdimensioning strategy, on a cell percell basis

an appropriate upgrade philosophy

SDDCH channels may bedimensioned in 3 ways on a cell per cell basis on a generic macro layer (not linked

to macro/ micro cell layer definitions) on both of the above

4 Network Dimension Ing

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