Cell Planning Principles[1]

Communications, Inc.

1

CELL PLANNING PRINCIPLES


2

Cell Planning Principles Course Outline:

• GSM System Review

• GSM Overview

• Radio Waves

• Modulation

• Interference

• Traffic Theory

• Cell Planning Process

• Nominal Cell Plan

• System design

• Installation

• System Tuning


3

GSM System Review

GSM - Global System for Mobile Communications

Other cellular technologies:AMPS - Advanced Mobile Phone SystemCDMA - Code Division Multiple AccessD-AMPS - Digital AMPS / or TDMA / or IS-54DCS1800 - Digital Communications System 1800NMT - Nordic Mobile TelephonePCS - Personal Communications SystemPDC - Personal Digital CellularTACS - Total Access Communications System


4

THE DIFFERENT GSM BASED NETWORKS

Network Type Frequency Band Uplink/Downlink

GSM900 890-915 935-960 MHzGSM1800 1710-1785 1805-1880 MHzGSM1900 1850-1910 1930-1990 MHz

GSM System Review


5

GSM System Review

GENERIC CELLULAR SYSTEM CONFIGURATION

PSTN MTSO Cell SiteMobile

T1 leased linesor

Microwave link

PLMN/CMTS


6

MobileStation

Air Interface

BaseTransceiver

Station

A-bisInterface

A Interface

Mobile Switching Center

Base StationController

Home LocationRegister

Gateway MSCVisitorLocatio

nRegiste

r

NetworkManagement

Subsystem

Base Station Subsystem

Network Switching Subsystem

ShortMessageService Center

GSM Network

GSM System Review


7

AIR INTERFACEFrequency Allocation

Radio Channel

DOWNLINK935 - 960 MHz

UPLINK890-915 MHz

Air Interface

Cell SiteMobile

GSM System Review


8

Lower Frequency for UPLINK?

• Save power for MS• Lower frequency is penetrating(analogy to disco sound)

GSM System Review


9

FREQUENCY SPECTRUMCMTS Operators in the Philippines

824 835 845 890 897.5 905 915

Piltel Extelcom Globe Smart Islacom

869 880 890 935 942.5 950 960

Piltel Extelcom Globe Smart Islacom

Standard GSM900 FrequencyAllocation 890-915/935-960

UPLINK

DOWNLINK

Smart’s GSM900

GSM System Review


10

CHANNEL CONCEPT (P-GSM900)

25 MHz BW

UPLINK DOWNLINK

890 915 935 960880 925

CARRIER SEPARATION = 200 KHzThis separation is needed to reduce interference from one carrier toanother neighboring frequency.The first carrier starts at 890.2 MHz.

890.2

E-GSM900 E-GSM900

GSM System Review


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DUPLEX DISTANCE

UPLINK DOWNLINK

890 915 935 960880 925

DUPLEX DISTANCE45 MHz

The distance between the uplink and the downlink frequenciesis known as DUPLEX DISTANCE.

Standard GSM900 GSM1800GSM1900Duplex Distance 45 MHz 95 MHz 80 MHz

GSM System Review


12

LOGICAL CHANNELS

On every physical channel, a number oflogical channels are mapped. Each logical channel is used for a specific purpose.

11 Logical Channels in the GSM system:2 are used for Traffic9 are used for Control Signaling

GSM System Review


13

LOGICAL CHANNELS

TRAFFIC CHANNELS (TCH)Full Rate ChannelHalf Rate Channel

CONTROL CHANNELS (with horrible abbreviations!)Broadcast Channels (BCH)

Frequency Correction Channel (FCCH)Synchronization Channel (SCH)Broadcast Control Channel (BCCH)

Common Control Channels (CCCH)Paging Channel (PCH)Random Access Channel (RACH)Access Grant Channel (AGCH)

Dedicated Control Channels (DCCH)Stand alone Dedicated Control Channel (SDCCH)Slow Associated Control Channel (SACCH)Fast Associated Control Channel (FACCH)

GSM System Review


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Hey! Don’t shoutat me, lower your

power...

BROADCAST CHANNELSall downlink!

FCCH

SCH TDMA#…BSIC...

BCCH

Hey. I’m aGSM xmitter!

GSM?

GSM!!!

LA…neigbors…cell info…max power...

Ok…ok

GSM System Review


15

COMMON CONTROL CHANNELS

PCH downlink only

Hello! You have a call.

RACH uplink only

Hello! I have to setup a call.

I need SDCCH.

AGCH downlink only

Ok. Use SDCCH.

GSM System Review


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DEDICATED CONTROL CHANNELSuplink and downlink

SDCCH

SACCHtiming advanceMS power

FACCH

handover

On SDCCH:-call set up signaling-location updating-periodic registration-IMSI attach/detach-SMS-facsimileetc…..

On SACCH-mobile transmits signalstrength on ncell quality

Don’t shout at me.I can’t hear you little butt.

GSM System Review


17

ACCESS METHODS

FDMA CDMA TDMAFrequency Division Code Division Time Division

f1

f2

f3

TDMA is usedin GSM system

GSM System Review


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FRAME STRUCTURE1 TDMA Frame = 8 TDMA Time Slots

0 1 2 3 4 5 6 7

4.615 ms

Tail Data F Training DataF Tail

Or Speech

Flag

3 000

57 1 26 1 57 3

Burst 148 bits

156.25 bits 0.577 ms

Basic TDMA frame, timeslot and burst structure

GSM System Review


19

RADIO WAVE PROPAGATION

H

Ezy

x

H = Magnetic FieldE = Electric Field

Direction of Travel

An Electromagnetic Plane Wave“Frozen” in Time

GSM System Review


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Two important features of the electromagneticwave are worth noting:

1. it is a transverse wave2. it requires no medium for its transmission

GSM System Review


21

RADIO FREQUENCY SPECTRUM

FREQUENCY CLASSIFICATION DESIGNATION

3-30 Hz30-300 Hz Extremely Low Frequency ELF300-3000 Hz Voice Frequency VF3-30 KHz Very Low Frequency VLF30-300 KHz Low Frequency LF300-3000 KHz Medium Frequency MF3-30 MHz High Frequency HF30-300 MHz Very High Frequency VHF300-3000 MHz Ultra High Frequency UHF3-30 GHz Super High Frequency SHF30-300 GHz Extremely High Frequency EHF300-3000 GHz

CellularSpectrum!

GSM System Review


22

GENERATION OF RADIO WAVES

freq

freq

transmitting antenna

GSM System Review


23

TRANSMITTING ANTENNA

1. Reference Antennas- Isotropic (exists as a mathematical concept)- Half-Wave Dipole

2. Practical Antennas - all practical antennas exhibit some degree of

directivity.

GSM System Review


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dBi vs dBd

dBi is a unit to measure antenna gainin reference to an isotropic antenna.An isotropic antenna has a power gain of unity; i.e., O dBi.

dBd is a unit to measure antenna gain inreference to a lossless half-wave dipole antenna. A lossless half-wave dipole antenna has a power gain of 0 dBd.

CONVERSION FACTOR:

dBi = dBd + 2.15 dB

GSM System Review


25

antenna lobe

maximum gain-3 dB

maximum gain-3 dB

main directionBEAMWIDTH

BEAMWIDTH

Beamwidth, B, is defined as the opening angle between the pointswhere the radiated power is 3 dB lower than in the main direction.Both the horizontal and the vertical beamwidths are found using the3 dB down points, alternatively referred to as the half-power points.

GSM System Review


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SUPERIMPOSING INFORMATIONON RADIO WAVES

Modulation???

GSM System Review


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...narrowing the bandwidth of the modulated carrier...

The modulation technique used inGSM is calledGaussian Minimum Shift Keying (GMSK).

- narrowband digital modulation technique.- based on phase shifting.

GSM System Review


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RADIO WAVE PROPAGATION AND THEPATHLOSS CONCEPT

transmitter/emitter(receiver)

receiver(transmitter/emitter)

transmission loss!!!

Factors that affect the wave propagation...

absorptionrefractionreflectiondiffractionscattering effect

GSM System Review


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absorptionrefractionreflectiondiffractionscattering effect

In free space, an electromagnetic wave travels indefinitely if unimpeded.

Assume a simple model isotropic antenna in free spacepropagation...

GSM System Review


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Free Space Model:Lp = 20 log (4*pi*d)/lambda

d

From the free space model, the mostimportant features of radio wave propagation are:1. the received power decreases when thedistance between the antennas increases.2. transmission loss increase when thewavelength decrease (or alternativelywhen the frequency increase).

GSM System Review


31

SIGNAL VARIATIONS

FADINGSFADINGSINTERFERENCEINTERFERENCE

GSM System Review


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FADINGSsignal level (dB)

log (distance)

global mean value

log normal fadinglocal mean valueslow fadingshadowinglong-term fading

rayleigh fadingfast fadingshort-term fading

so many namesto make life

worst!

GSM System Review


33

FAST FADINGsignal level (dB)

log (distance)

• present due to the fact that the mobile antenna is lowerthan the surrounding structures such as trees and buildings.• peak-to-peak distance is ~ lambda/2 (in GSM ~ 17 cm)• affects the signal quality and can lead to signal level belowthe receiver sensitivity.

SOLUTIONS:• use more power at the transmitter (providing a fading margin).• use space diversity.

GSM System Review


34

SLOW FADINGsignal level (dB)

log (distance)

• if we smooth out the fast fading, the signal variationreceived is called the “local mean” or the slow fading.• caused by obstructions near the mobile such asbuildings, bridges and trees and this may cause a rapid change of the local mean (in the range of 5 to 50 meters).• because slow fading reduces the average strengthreceived, the total coverage from the transmitter is reduced.

SOLUTION:• fading margin must be used.

GSM System Review


35

INTERFERENCE• co-channel interference

• adjacent channel interference

Co-channel interference is the term used for the interference in a cellby carriers with the same frequency present in other cells.

Adjacent carrier frequencies, i.e. frequencies shifted +/- 200 kHz withrespect to the carrier, can not be allowed to have too strong signalstrengths either. Even though they are at different frequencies, part of the signal can interfere with the wanted carrier’s signal and causequality problems.

f1f1

co-channel

wanted carrier

adjacentcarrier

GSM System Review


36

CO-CHANNEL INTERFERENCE

C I

C

I

C/I > 0 dB

dB Carrier, f1 Interferer, f1

distanceGSM Specification: C/I => 9 dBEricsson Planning Criterion:C/I => 12 dB (without frequency hopping)C/I => 9 dB (with frequency hopping)

GSM System Review


37

ADJACENT CHANNEL INTERFERENCE

C A

A

C

C/A< 0 dB

dB Carrier, f1Adjacent, f2f2=f1 +/- 200 kHz

distanceGSM Specification: C/A > -9 dBsince we could not cell plan a negative valueEricsson Planning Criterion:C/A > 3 dB


38

InterSymbol Interference

• caused by excessive time dispersion.• it may be present in all cell re-use pattern.• it can be thought of as a co-channel interference.• in this case, the interferer is a time delayed reflection

of the wanted carrier.• GSM specification: C/R > 9 dB• however, if the time delay is smaller than 15

microseconds, i.e. 4 bits or approximately 4.4 km, theequalizer can solve the problem.

D0

D1D2

GSM System Review


39

TRAFFIC THEORY Traffic and Channel Dimensioning

Traffic theory attempts to obtain useful estimates of the numberof channels needed in a cell...

= HOW MANY CUSTOMERS?= HOW LONG WILL THEY TALK?= WHEN?

FACTORS AFFECTING THE CELLULAR SYSTEM CAPACITY:• The number of channels available for voice and/or data.• The amount of traffic the subscribers are generating.• The grade of service the subscribers are encountering in the system

GSM System Review


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• The number of channels available for voice and/or data.

Assume 1 cell has 2 carriers:2 x 8 - 2 = 14

14 traffic channels2 physical channels are

needed for signaling

GSM System Review


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• The amount of traffic the subscribers are generating.

What is traffic?• the usage of channels• holding time per time unit• the number of “call hours” per hour• measured in the unit Erlang (E)


42


1 Erlang = 1 call that last 1 hour!

...studies show that the averagetraffic per subscriber during thebusy hour is typically 15 - 20 mE...

Typical actual values:

Philippines (Smart E-TACS)7 mE/subscriber - Metro Manila8 mE/subscriber - Provincial

Malaysia and Sweden25 mE/subscriber


43


visualize 15 mE !1 E = 1 hour of use15 mE = ? hour of use15 mE / 1 E = 0.015~ 1.5% of 60 min = 0.9 min x 60 sec15 mE = 54 seconds of use15 mE = 54 seconds of use

GSM System Review


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• The grade of service the subscribers are encountering in the system.

How much trafficcan one cell carry?

• That depends on the number oftraffic channels and the acceptable

probability that the system iscongested, the so called

“Grade of Service” (GoS)...

GSM System Review


45


Grade of Serviceis the

Grade of NO SERVICE !

- unsuccessful call set-up- GoS = 2% means

98% can make a call2% blocking probability

GSM System Review


46

Alien !!!


Erlang’s B-Model - “loss system”• no queues• number of subscribers much higher than number of traffic channels • no dedicated (reserved) traffic channels• Poisson distributed (random) traffic• blocked calls abandon the call attempt immediately

GSM System Review


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Erlang’s B-Model relates:• number of traffic channels, n• the GoS• the traffic offered, A

Example:2 carriers14 TCHGoS = 2%from the Erlang Table...Traffic Offered, A = 8.2003 Erlangs

GSM System Review


48

In GSM, a call goes through two different devices.

TCH & SDCCH

SDCCH procedures:• location updating• periodic registration• IMSI attach• IMSI detach• call setup• SMS (Short Message Services)• facsimile• other supplementary services

SDCCH TCH

GSM System Review


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CHANNEL UTILIZATION (EFFICIENCY)

VS

GSM System Review


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CHANNEL UTILIZATION (EFFICIENCY)

VS

To calculate the channel utilization, thetraffic offered is reduced by the GoS (yieldingthe traffic served), and dividing that valueby the number of channels.

Traffic Offered - GoS (Traffic Offered)Channel Utilization =

Number of Channels

GSM System Review


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Cell Planning Principles Course Outline:

• GSM System Review

• GSM Overview

• Radio Waves

• Modulation

• Interference

• Traffic Theory

• Cell Planning Process

• Nominal Cell Plan

• System design

• Installation

• System Tuning


52

CELL PLANNING PROCESS

Traffic and Coverage Analysis

Nominal Cell Plan

Surveys

System Design

Implementation

System Tuning

TRAFFIC DATATRAFFIC DATA

Initial PlanningSystem Growth


53



Nominal Cell Plan

Surveys

System Design

Implementation

System Tuning



geographical area.expected need ofcapacity.

cell pattern on a map.coverage & interferenceprediction.

visit sites whereradio equipmentwill be placed.perform radiomeasurements.dimensioning of the

rbs equipment, BSC & MSC.CDD is filled out.

system installation,commissioningand testing are performed.

continually evaluated todetermine how well it meetsthe demand.


54

SYSTEM BALANCE

Objectives of System Balancing(Simple Link Budget Analysis)

to estimate the maximum allowable path loss to compute the required BS transmitter power

for a balanced path to estimate the coverage design threshold to evaluate technology performance



55

SYSTEM BALANCE

PinBTS

BTSsens



56

WHY BALANCED PATH?

BS does nothear the MS

MS hears the BS

Strong Signal Weak Signal

UPLINK LIMITED:

DOWNLINK LIMITED:

BS hears the MSMS does nothear the BS

Weak Signal Strong Signal



57

HOW TO BALANCE PATH?Coverage in a two-way radio communication system is decidedby the weakest transmission direction.

AssumeUplink Limited

Balance Path Compute BSTx Power Output

Path Loss in Uplink = Path Loss in Downlink

Balanced Path:



58

Schematics of the Components Included in a System Balance

Tx Combiner Feeder

Feeder

RxTx

RxReceiverDivider

Feeder

FeederGdBTS

LcBTS LfBTS

GaBTS Lp

Lp

GaMS

LfMS

PinBTS

PoutBTS

LfBTS

GaBTS

PoutMS PinMS



59

EFFECTIVE RADIATED POWERERP vs EiRP

ERP (Effective Radiated Power): is the radiated power (transmit power times antenna gain) with respect to a dipole antenna within a given geographic area.EiRP (Effective Isotropic Radiated Power): is the radiated power from an isotropic antenna.

EiRP = ERP + 2.15 (dB)

EiRPLp

SSdesign



60

CHANNEL PLANNING

The simplest solution to acell planning problem is tohave one cell and use allavailable carriers in that cell.

1 cell24 carriers

f1 - f24



61

CELL PLANNING

A cellular system is basedupon re-use of the same setof carriers, which is obtainedby dividing the area needingcoverage into smaller areas (cells) which together formclusters.

f1 f1

f1f1

24

24

24

24



62

RE-USE PATTERNS

Re-using the carrier frequencies according to well-provenre-use patterns , neither co-channel interference nor adjacent channel interference should become a problem,if the cells have homogenous propagation properties forthe radio waves.

The re-use patterns recommendedfor GSM are:

• 4/12 pattern• 3/9 pattern

4/12 means that there are 4 three sector sites supporting 12 cells



63

4/12 RE-USE PATTERN

D3

D2

D1

A1

A2

A3

C1

C2

C3

B1

B2

B3

D3

D2

D1

A1

A2

A3

C1

C2

C3

B1

B2

B3

D3

D2

D1

A1

A2

A3

C1

C1

C3

B1

B2

B3

D3

D2

D1

D3

D2

D1

B1

B2

B3

B1

B2

B3

C2



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3/9 RE-USE PATTERN

C1

C2

C3

A1

A2

A3

B1

B2

B3

C1

C2

C3

A1

A2

A3

B1

B2

B3

C1

C2

C3

A1

A2

A3

B1

B2

B3

C1

C2

C3

A1

A2

A3

B1

B2

B3

C1

C2

C3

A1

A2

A3

B1

B2

B3



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As an example, suppose that one operator has been given5 MHz of bandwidth and distributes the carriers over nine cells, itcan look like:

ChannelGroups A1 B1 C1 A2 B2 C2 A3 B3 C3

512 513 514 515 516 517 518 519 520RF 521 522 523 524 525 526 527 528 529Channels 530 531 532 533 534 535

Frequencies in the 3/9 cell plan.The Absolute Radio Frequency numbers (ARF) given here correspondto the frequency interval 1710 - 1715 MHz in GSM1800. Note that theadjacent cells A1 and A3 also have adjacent frequencies 200 KHzapart =

f(ARFCN) = 1710.2 + 0.2(ARFCN-512)



66

TRANSITION REGIONS

A uniform re-use pattern implies a constant trafficdensity over the network’s coverage area.

In practice, however, traffic density variesconsiderably over the area (and during the day). Thismeans it is common that cells of different sizes areused in different parts of the system.

Small cells in high traffic areas(normally urban), and large cellsin areas with lower traffic.



67

NCC & BCCNetwork Color Code and Base Station Color Code

The Base Station Identity Code (BSIC) is composed of two entities:• Network Color Code (NCC)

• BTS Color Code (BCC)

f1 f1

Country A

Country BNCC=1

NCC=2

The use of NCC in two countries



68

C1

C2

C3

A1

A2

A3

B1

B2

B3

C1

C2

C3

A1

A2

A3

B1

B2

B3

C1

C2

C3

A1

A2

A3

B1

B2

B3

C1

C2

C3

A1

A2

A3

B1

B2

B3

C1

C2

C3

A1

A2

A3

B1

B2

B3

NCC & BCCNetwork Color Code and Base Station Color Code

3

1

4

2

2

BCC is used forprotection againstco-channel interferencewithin the PLMN.

The MS reports the BCCvalue so that the BSC candistinguish among different cells transmittingon the same frequency.



69

PROPAGATION PREDICTIONS

The Definition of Coverage

An area is covered if in 90 (95-99) percentof that area the signal received by the mobilestation is larger than some design value, forexample -90 dBm, i.e. SSdesign = -90 dBm.

That is, PinMS => SSdesign

The signal strength requirement is estimated byadding margins to the MS receiver sensitivity. These are: fast and slow fading margins

margins for body lossmargins for in-car & indoor coverage

The margins depend on the type of environment andoperator requirments.



70

PROPAGATION PREDICTIONS

Predict the Path Loss

It is very important to be able to estimate the signalstrength in all parts of the area to be covered. That is,to predict the path loss.

Propagation Models:• Free Space Model• Flat Conductive Earth Model• Knife Edge Diffraction Model• Okumura-Hata Model• Ericsson’s Modified Okumura-Hata Model• Ericsson’s Algorithm 9999 Model• Cost 231-Walfish-Ikegami Model• etc...



71

FLAT CONDUCTIVE EARTH

h1

h2

dBase Mobile

assumption: h1*h2 <<< wavelength* d

L = 20 log [ d2 / (h1*h2)]



72

KNIFE EDGE DIFFRACTION

TXRX

h

d1 d2

v = h 2 (d1+d2)

d1d2

We can contend ourselveswith expressing additionalattenuation, caused by theseso called “knife edges” ina diagram. The additionalattenuation is read of as afunction of the parameter v.



73

SEMI-EMPIRICAL MODELS

OKUMURA-HATA MODEL

Lp(urban) = 69.55+ 26.16logf - 13.82loghb + (44.9 - 6.55loghb)logd - a(hm)

whereLp = Path Loss in dBa(hm) = (1.1logf - 0.7)hm - (1.56logf - 0.8)f = carrier frequency in MHz (150-1000 MHz)hb = the base station antenna height in meter (30-200m)d = distance in km from the base station (1-20 km)hm = mobile antenna height in meter above ground (1-10m)



74

SEMI-EMPIRICAL MODELS

ERICSSON’s MODIFIED OKUMURA-HATA MODEL

Lp = A - 13.82loghb + (44.9 - 6.55loghb)logd - a(hm)

whereLp = Path Loss in dBa(hm) = 3.2(log 11.75 hm)2 - 4.97

and

Urban Areas : A(900) = 146.8 and A(1800) = 153.8Suburban Areas : A(900) = 136.9 and A (1800) = 146.2Open Areas : A(900) = 118.3 and A (1800) = 124.3



75

OTHER SEMI-EMPIRICAL MODELS

• ALGORITHM 9999 - prediction model usedby Ericsson (valid between 0.2 - 100 km) is based on ideassimilar to Hata’s.• COST231-HATA - for GSM1900 (1500-2000 MHz)• COST231-WALFISH-IKEGAMI - valid between 0.02 - 5 km. Used in urban areas because it usesstreet orientation, building heights, building separationsand road widths.

ALGORITHM 9999 and Cost231-Walfish-Ikegami Models are supported by EET.


76


Nominal Cell Plan

Surveys

System Design

Implementation

System Tuning


Based on ERICSSON




77

RADIO NETWORK SURVEY

Basic Considerations:• Position relative to nominal grid• Space for antennas• Antenna separations• Nearby obstacles• Space for radio equipment• Power supply / battery backup• Transmission link• Service area study• Contract with owner



78

SPACE FOR ANTENNAS

PLANNING CRITERIA

• The predicted antenna height should be used as a guideline. The original predictions can be used with sufficient accuracy if spacefor antennas can be found within an acceptable distance from thepredicted height. A deviation of maximum 15% is required.

• If it is possible to install antennas at a higher position than the predicted position, the operator must ensure that there is no riskfor co-channel interference.

• If the antennas are to be installed at a lower position than predicted, new predictions must be carried out based on thisposition.



79

ANTENNA SEPARATIONS

PLANNING CRITERIA• SPACE DIVERSITYHorizontal separation is normally more efficient compared tovertical separation. The planning criterion specifies making ahorizontal separation equal to or more than 10% of the effectiveantenna height.

Horizontal Separation = 4 meters (900 MHz)= 2-3 meters (1800-1900 MHz)

Vertical separation requires approximately 5 x thehorizontal value in order to get the same diversity gain.

• ISOLATIONIn order to avoid disturbance due to intermodulation, the transmit and receive parts of the base station must be isolated.

Tx-Rx = 30 dBTx-Tx = 30 dBHorizontal Separation = 0.4 meter (900 MHz, 65 deg BW)Vertical Separation = 0.2 meter (900 MHz, 65 deg BW)



80

NEARBY OBSTACLES

PLANNING CRITERIA

• If optimal coverage is required, it is necessary to have the antennasfree for the nearest 50 -100 m. The first fresnel zone is approximately5 meters at this distance (for 900 MHz). This means the lower partof the antenna system has to be 5 meters above the surroundings.

5 meters

50 - 100 m



81

SITE EQUIPMENT

BSC

BTS

Base Station System (BSS)

The BSS consists of a Base Station Controller (BSC) with a numberof base stations connected to it. The BSS is mainly responsible forall radio related functions in the system. In the GSM specifications, thedetonation BTS (Base Transceiver Station) is used for the base station.

site equipment



82

SITE REQUIREMENTS

• Permits• Access Roads• Material Transport and Storage • Space Requirements• Antenna Support Structures• AC Mains Supply• Transmission Access• Antenna Feeder Routes



83

BTS EQUIPMENT

EricssonNokiaNortelLucent

MotorolaAlcatel



84

COMBINERS

transmitter 2

transmitter 3

transmitter n

transmitter 1

combiner

Combiners are needed to enable more thanone transmitter to be connected to onecommon transmitting antenna.

In GSM, two different TX combiners can beused -

• FILTER COMBINER• HYBRID COMBINER



85

SENSITIVITY

BTScabinet Feeder & Jumpers ALNA

Without ALNARX ref point 2

With ALNARX ref point 1

System Cell Planning Worst CaseSensitivity Sensitivity

GSM900 - 107 dBm - 105 dBmGSM1800 with ALNA - 109 dBm - 107 dBmGSM1800 w/o ALNA - 106 dBm - 104 dBm

Base station receiver sensitivityValid for both Ericsson’s RBS2000 and RBS200/205

Micro Base Station: Cell Planning Power = 1.6W, 32 dBm Worst Case Sensitivity = - 104 dBm

Base Station



86

SENSITIVITY

System MS Power Cell Planning Worst CaseClass Power Power

GSM900 2 39 dBm (8W) 37 dBmGSM900 3 37 dBm (5W) 35 dBmGSM900 4 (handheld) 33 dBm (2W) 31 dBmGSM900 5 (handheld) 29 dBm (0.8W) 27 dBmGSM18001 30 dBm (1W) 28 dBmGSM18002 24 dBm (0.25W) 22 dBm

Mobile Station Power Classes

Mobile Station Reference Sensitivity

System MS Type Cell Planning Worst CaseSensitivity Sensitivity

GSM900 Handheld - 104 dBm - 102 dBmGSM900 All other types - 106 dBm - 104 dBmGSM1800Handheld - 102 dBm - 100 dBm

No loss or antenna gain should be used for the MSs.

MS antenna gain: 0 dBi



87

Antenna Diversity

There is a need for receiver diversity in cellular systemsto improve the uplink.

Space Diversity

TX1/RXA TX1/RXABTS Equipment

CommonTX/RXAntenna

dd

Horizontal Separation, dd

for diversity = 12-18 (wavelength)

for isolation = 30 dB = 2 (wavelength)[antennas with 65 degrees beamwidth,all gain values]



88

Antenna Diversity


Polarization Diversity using dual-polarized antennas

vertical + horizontal polarization +/- 45 degrees polarization

verticalarray

horizontalarray

antennahousing

connectors

feeders

+45degrees

- 45degrees



89


Polarization Diversity using dual-polarized antennas

1.5 dB downlink loss

TX1/RXA TX1/RXA

Required isolation >30 dB betweenthe two antenna parts...

Antenna Diversity



90

Antenna Diversity


SPACE DIVERSITYVSPOLARIZATION DIVERSITY



91

ANTENNA TILT

When the antenna is mounted vertically,the main lobe of the antenna radiationpattern will follow a horizontal linestarting at the center point of the antenna.



92

ANTENNA TILT

For reasons, such as co-channel interferenceand time dispersion problems, it can be interestingto tilt the antenna, and let the main lobe pointa few degrees downward.



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Nominal Cell Plan

Surveys

System Design

Implementation

System Tuning


Based on ERICSSON




94

Macrocell CharacteristicsMacrocell Characteristics

• Provides cellular coverage to Urban and Rural areasProvides cellular coverage to Urban and Rural areas

• Has large coverage area and high capacityHas large coverage area and high capacity

• Provide good outdoor coverage but limited indoor coverageProvide good outdoor coverage but limited indoor coverage

• Requires high location for antennas, usually mounted on tower or Requires high location for antennas, usually mounted on tower or rooftop of the building.rooftop of the building.

• Provides large coverage area Provides large coverage area

• Provides large capacityProvides large capacity

• Better signal reception and voice qualityBetter signal reception and voice quality

• Less call dropoutLess call dropout

• Better overall network qualityBetter overall network quality

Macrocell BenefitsMacrocell Benefits



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Macrocell ConceptMacrocell Concept



96

Installation RequirementInstallation Requirement

Bldg. SitesBldg. Sites

• Radio Room Space (min. 3.0 m x 3.0 m)Radio Room Space (min. 3.0 m x 3.0 m)Base Station EquipmentBase Station EquipmentPower EquipmentPower EquipmentTransmission EquipmentTransmission Equipment

• Antenna Space (rooftop)Antenna Space (rooftop)Cellular Panel/Omni AntennasCellular Panel/Omni AntennasParabolic Transmission AntennaParabolic Transmission Antenna

• Cable RoutingCable RoutingCoaxial CableCoaxial CableTransmission CableTransmission Cable

Lot SitesLot Sites

• min. 20 m x 15 m space requirementmin. 20 m x 15 m space requirement



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Sample Site LayoutSample Site Layout



98

Sample Equipment Room LayoutSample Equipment Room Layout



99

Sample InstallationsSample Installations

Equipment VanEquipment Van

AntennaAntenna

80 ft. Monopole Tower80 ft. Monopole Tower



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Equipment ShelterEquipment Shelter

AntennaAntenna

200 ft. Self-support Tower200 ft. Self-support Tower

Sample InstallationsSample Installations



101


Nominal Cell Plan

Surveys

System Design

Implementation

System Tuning


Based on ERICSSON




102

SYSTEM TUNING

• Network Dimensioning• Frequency Planning• Predicting• Tools

Prediction Tools

othersNokia’s NMS/XNortel’s PlaNETetc



103

SYSTEM TUNING

• Ericsson’s Test Mobile System (TEMS)

Drivetest Equipment

MS

PC

GPS



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SYSTEM GROWTH

• Increase the frequency band (e.g. a GSM900operator might buy a GSM1800 licenses)• Implement half-rate• Tighter frequency re-use (e.g. going from a4/12 re-use pattern to a 3/9 re-use pattern byimplementing frequency hopping)• Make the cells smaller and smaller

SYSTEM TUNING



105

CELL SPLIT Phase 0



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CELL SPLIT Phase 1



107

CELL SPLIT Phase 2 (1:3)



108

CELL SPLIT Phase 2 (1:4)



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QUALITY MEASURES:• CapacityQuality in terms of traffic capacity, as measured in number ofsubscribers per square kilometer.• Subscriber service qualityQuality as perceived by the subscribers. Examples are call setupsuccess rate and number of dropped calls.• Network service qualityQuality as perceived by the network operator. Examples are featuresthat can be used to simplify dimensioning of the radio resources,and features that aid in operation and management of the radionetwork.

SYSTEM TUNING


Documents

Cell Planning Principles[1]