cell planning principles[1]
DESCRIPTION
Cell Planning Principles[1]TRANSCRIPT
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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
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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
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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
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GSM System Review
GENERIC CELLULAR SYSTEM CONFIGURATION
PSTN MTSO Cell SiteMobile
T1 leased linesor
Microwave link
PLMN/CMTS
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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
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AIR INTERFACEFrequency Allocation
Radio Channel
DOWNLINK935 - 960 MHz
UPLINK890-915 MHz
Air Interface
Cell SiteMobile
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Lower Frequency for UPLINK?
• Save power for MS• Lower frequency is penetrating(analogy to disco sound)
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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
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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
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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
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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
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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)
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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
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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.
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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.
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ACCESS METHODS
FDMA CDMA TDMAFrequency Division Code Division Time Division
f1
f2
f3
TDMA is usedin GSM system
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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
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RADIO WAVE PROPAGATION
H
Ezy
x
H = Magnetic FieldE = Electric Field
Direction of Travel
An Electromagnetic Plane Wave“Frozen” in Time
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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
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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!
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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.
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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
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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.
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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.
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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
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RADIO WAVE PROPAGATION AND THEPATHLOSS CONCEPT
transmitter/emitter(receiver)
receiver(transmitter/emitter)
absorptionrefractionreflectiondiffractionscattering effect
In free space, an electromagnetic wave travels indefinitely if unimpeded.
Assume a simple model isotropic antenna in free spacepropagation...
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RADIO WAVE PROPAGATION AND THEPATHLOSS CONCEPT
transmitter/emitter(receiver)
receiver(transmitter/emitter)
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).
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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!
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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.
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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.
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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
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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)
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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
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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
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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
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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
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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)
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• The amount of traffic the subscribers are generating.
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
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• The amount of traffic the subscribers are generating.
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
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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)...
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• The grade of service the subscribers are encountering in the system.
Grade of Serviceis the
Grade of NO SERVICE !
- unsuccessful call set-up- GoS = 2% means
98% can make a call2% blocking probability
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Alien !!!
• The grade of service the subscribers are encountering in the system.
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
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• The grade of service the subscribers are encountering in the system.
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
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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
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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
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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
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CELL PLANNING PROCESS
Traffic and Coverage Analysis
Nominal Cell Plan
Surveys
System Design
Implementation
System Tuning
TRAFFIC DATATRAFFIC DATA
Initial PlanningSystem Growth
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CELL PLANNING PROCESS
Traffic and Coverage Analysis
Nominal Cell Plan
Surveys
System Design
Implementation
System Tuning
TRAFFIC DATATRAFFIC DATA
Initial PlanningSystem Growth
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.
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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
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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
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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:
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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
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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
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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
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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
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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
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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)
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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.
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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
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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.
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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.
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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...
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FLAT CONDUCTIVE EARTH
h1
h2
dBase Mobile
assumption: h1*h2 <<< wavelength* d
L = 20 log [ d2 / (h1*h2)]
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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.
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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)
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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
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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.
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Traffic and Coverage Analysis
Nominal Cell Plan
Surveys
System Design
Implementation
System Tuning
TRAFFIC DATATRAFFIC DATA
Based on ERICSSON
Initial PlanningSystem Growth
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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
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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.
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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)
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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
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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
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SITE REQUIREMENTS
• Permits• Access Roads• Material Transport and Storage • Space Requirements• Antenna Support Structures• AC Mains Supply• Transmission Access• Antenna Feeder Routes
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BTS EQUIPMENT
EricssonNokiaNortelLucent
MotorolaAlcatel
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Communications, Inc.
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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
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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
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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
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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]
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Communications, Inc.
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Antenna Diversity
There is a need for receiver diversity in cellular systemsto improve the uplink.
Polarization Diversity using dual-polarized antennas
vertical + horizontal polarization +/- 45 degrees polarization
verticalarray
horizontalarray
antennahousing
connectors
feeders
+45degrees
- 45degrees
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There is a need for receiver diversity in cellular systemsto improve the uplink.
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
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Communications, Inc.
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Antenna Diversity
There is a need for receiver diversity in cellular systemsto improve the uplink.
SPACE DIVERSITYVSPOLARIZATION DIVERSITY
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Communications, Inc.
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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.
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Communications, Inc.
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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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Traffic and Coverage Analysis
Nominal Cell Plan
Surveys
System Design
Implementation
System Tuning
TRAFFIC DATATRAFFIC DATA
Based on ERICSSON
Initial PlanningSystem Growth
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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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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 Equipment Room LayoutSample Equipment Room Layout
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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
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Traffic and Coverage Analysis
Nominal Cell Plan
Surveys
System Design
Implementation
System Tuning
TRAFFIC DATATRAFFIC DATA
Based on ERICSSON
Initial PlanningSystem Growth
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SYSTEM TUNING
• Network Dimensioning• Frequency Planning• Predicting• Tools
Prediction Tools
othersNokia’s NMS/XNortel’s PlaNETetc
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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
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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
CELL PLANNING PROCESS