Modul 6 antenna & related equipments
54
GSM-GPRS Operation Antenna And Equipment Related Module 6
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Describe about GSM Physical hardwares. Antennas, BTS Module, etc...
Transcript of Modul 6 antenna & related equipments
GSM-GPRS Operation
Antenna And Equipment Related
Module 6
2
Outline
Base station antenna specification and meanings
Antenna types and trends
Antenna Type And Developments
Other Elements
3
BTS Logic Structure
BSC
Basebandsubsystem
Power supplysubsystem
RFsubsystem
Abisinterface
Uminterface
MSAntenna & feeder
subsystem
-48V/+24V
4
Antennas Categories
Omnidirectional antennas radiation patterns is constant in the
horizontal plain useful in flat rural areas
Directional antennas concentrate main energy into certain
direction larger communication range useful in cities, urban areas, sectorised
sites
5
RF Antenna and Feeder
Sect
or ¦A
Sect
or¦A
Sect
or¦A
Antenna
Feeder
Jumper
Jumper
BTS cabinet
Inner cable
TX/RXMA
NT
RXD
6
Antennas - Antenna Gain
Measures the antenna´s capability to transmit/extract energy to/from the propagation medium (air) dB over isotropic antenna (dBi) dB over dipole (dBd)
Antenna gain depends on mechanical size: A effective antenna aperture area: w frequency band
Antenna Gain:
G Aw4
2
Pt
Gain (Dbi)
Isotropic radiated Power
Equivalent isotropicradiated power:EIRP = Pt+Gain(Dbi)
radiatedpower
8
Antenna Properties
Electrical properties Operation Frequency Band Input impedance VSWR Polarization Gain Radiation Pattern Horizontal/Vertical beamwidth Downtilt Front/back ratio Sidelobe suppression and null filling Power capability 3rd order Intermodulation Insulation
Mechanical properties Size Weight Radome material Appearance and color Working temperature Storage termperature Windload Connector types Package Size Lightening
GSM-GPRS Operation
Antenna Electrical properties
10
Wavelength
1/2 Wavelength
1/4 Wavelength
1/4 Wavelength
1/2 Wavelength
Dipole
Dipoles
1800MHz 166mm
900MHz 333mm
11
1 dipole (received power) 1mWMultiple dipole matrix
Received power 4 mW
GAIN = 10log(4mW/1mW) = 6dBd
12
Gain = 10log(8mW/1mW) = 9dBi
“Sector antenna”Received power 8mW
“Omnidirectional array”Received power 1mW
(Overlook
Antenna
13
GSM 900 : 890-960MHz GSM 1800 : 1710-1880MHz GSM dual band : 890-960MHz
& 1710-1880MHz eg.824-960MHz 1710-1900MHz
CDMA2000 1x
Frequency Range
15
9.5 W80
ohms50 ohms
Forward: 10W
Backward: 0.5W
Return Loss 10log(10/0.5) = 13dB
VSWR (Voltage Standing Wave Ratio)
VSWR
20
Dipole
Ideal radiating dot source(lossless radiator)
eg: 0dBd = 2.15dBi
dBd and dBi
2.15dB
22
Beamwidth
120° (eg)Peak
Peak - 10dB
Peak - 10dB
10dB Beamwidth
60° (eg) Peak
Peak - 3dB
Peak - 3dB
3dB Beamwidth
25
Mechanical down tilt Fixed electronic down tilt Adjustable electronic down
tilt
Downtilt
31
Ratio of maximum mainlobe to maximum sidelobe
F/B = 10 log(FP/BP) typically 25dB
Back power Front power
Front to back ratio
36
IMD@243dBm f1, f2, 2f1-f2, 2f2-f1
913MHz,936MHz,959MHz,982MHz
Third Order Intermodulation
37
Intermodulation
Intermodulasi Terjadi akibat penguatan
sistem yang non linier Hanya orde ke-3 dan
kadang-kadang orde ke-5 yang signifikan
Sinyal dengan amplituda yang sama menghasilkan level IM yang sama pada frek tinggi dan rendah
Sinyal dengan amplituda berbeda memberikan level IM yang berbeda pula
Untuk mencegah intermodulasi,penguat dioperasikan pada penguatan bukan-maksimum
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Intermodulation
Intermodulasi
Komp. Orde 1 : diharapkan linier
Komp. Orde 2 : frek 2 diredam oleh filter
Komp. Orde 3 : frek 3 diredam dengan filter
Penguat Non-linier
tB
tAv
B
Ai
cos
cos
3
2
i
iio
cv
bvavv
Yang bermasalah :
Komponen yang lain amplituda kecil
ABBA 2,2
40
10 Simple Guidelines for RF Safety
All personnel should have EME awareness training All personnel entering the site must be authorized Obey all posted signs Assume all antennas are active Before working on antennas, notify owners and disable appropriate
transmitters Maintain minimum 3 feet clearance from all antennas Do not step in front of antennas Use personal RF monitors while working near antennas Never operate transmitters without shields during normal operation Do not operate base station antennas inside equipment rooms
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PVC, Fiberglass Anti-temperature, water-proof,
anti-aging, weather resistant
Radome Material
GSM-GPRS Operation
Antenna Types and Development
45
Antenna Types
By frequency band: GSM900, GSM1800, GSM900/1800
By polarization: Vertical, Horizontal, ±45º linear
polarization, circle polarization
By pattern: Omni-directional, directional
By down-tilt: Non, mechanical, electronic
adjustment, remote control
By function: Transmission, receiving, transceiving
47
def = Attenuation between TX & RX antenna connectors
Horizontal separation needs approx. 5 distance
for sufficient decoupling antenna patterns
superimposed if distance too close
Vertical separation distance of 1 provides
good decoupling values good for RX /TX decoupling
Minimum coupling loss
main lobe
5 .. 10
1
AntennasDecoupling
48
Installation Examples Recommended decoupling
TX - TX: ~20dB TX - RX: ~40dB
Horizontal decoupling distance depends on antenna gain horizontal rad. pattern
Omnidirectional antennas RX + TX with vertical separation (“Bajonett”) RX, RX div. , TX with vertical separation (“fork”)
Vertical decoupling is much more effective
0,2m
49
•Time diversity
•Frequency diversity
•Space diversity
•Polarisation diversity
•Multipath diversity
•interleaving
•frequency hopping
•multiple antennas
•crosspolar antennas
•equaliser•rake receiver
t
f
DiversityDiversity Technics
50
Diversity gain depends on environment
Is there coverage improvement by diversity ? antenna diversity
equivalent to 5dB more signal strength more path loss acceptable in link budget higher coverage range
R
R(div) ~ 1,3 RA 1,7 A ??70% more coverage per cell ??needs less cells in total ??
True only (in theory) if the environment is infinitely large
and flat
DiversityCoverage Improvement?
51
Network ElementsMHA
MastHead Amplifier(Low Noise Amplifier)
RX signal amplified near the antenna in the top of the mast
Offers better coverage Eliminates the antenna
cable loss Increased receiver
sensitivity of the BTS and cell size
Increased network quality
Noise Figure £ 2.0 dB (typical)RX Gain: Up to 12 dBDimensions : 266 x 130 x 123 mmWeight : 5.6 kg (duplexed)Volume : 4.2 lIP 65 Enclosure ProtectionPower Feeding Through Antenna CoaxAlarms handled in BTS
52
Booster
TX signal amplified
Nokia Booster Configuration
Booster (PA) Unit (TBU)
Booster Filtering Unit (AFH)
Masthead Preamplifier equipment (MHA)
Output power before combining can be up to 49 dBm
Isolator + combiner + filter (AFH) give roughly 2.5 dB losses
Booster BTS is suitable for all the environments where enhanced coverage or high output power is needed
Theoretically, cell radius is enhanced up to 60% and the coverage area is roughly the triple
Network Elements Booster
TRXTBUAFH
53
BTS Equipments layout
TOWER
BTSE
RECTIFIER
BATTERY
TRANSMISSION EQP.
SITE
GENSET
AC
Groundingsensor
ACPDB
Power PLN
SHELTER
GSM-GPRS Operation
End of Section 6
Antenna And Equipment Related
