A Study into the Theoretical Appraisal of the Highest Usable Frequencies RA Contract AY 4329.
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Transcript of A Study into the Theoretical Appraisal of the Highest Usable Frequencies RA Contract AY 4329.
![Page 1: A Study into the Theoretical Appraisal of the Highest Usable Frequencies RA Contract AY 4329.](https://reader035.fdocuments.net/reader035/viewer/2022062516/56649e205503460f94b0c602/html5/thumbnails/1.jpg)
A Study into the Theoretical Appraisal of the Highest
Usable Frequencies
RA Contract AY 4329
![Page 2: A Study into the Theoretical Appraisal of the Highest Usable Frequencies RA Contract AY 4329.](https://reader035.fdocuments.net/reader035/viewer/2022062516/56649e205503460f94b0c602/html5/thumbnails/2.jpg)
Contributors
• The study concentrated on the millimetric and Infra red bands
– Propagation Chris Gibbins (RAL)
– Technology Dave Matheson (RAL)
– Systems Applications John Norbury (Satconsult)
![Page 3: A Study into the Theoretical Appraisal of the Highest Usable Frequencies RA Contract AY 4329.](https://reader035.fdocuments.net/reader035/viewer/2022062516/56649e205503460f94b0c602/html5/thumbnails/3.jpg)
Systems Applications to be evaluated
• Point to point fixed services 1 to 10 km• broadband fixed wireless access (P-MP & Mesh)• satellite communications• HAPS• Mobile systems• Personal area networks• home communications• very high data rate indoor communications• short range anti-collision vehicle radar• comparison of free space optical (FSO) systems with
millimetre wave systems
![Page 4: A Study into the Theoretical Appraisal of the Highest Usable Frequencies RA Contract AY 4329.](https://reader035.fdocuments.net/reader035/viewer/2022062516/56649e205503460f94b0c602/html5/thumbnails/4.jpg)
Specific gaseous attenuation at sea level
![Page 5: A Study into the Theoretical Appraisal of the Highest Usable Frequencies RA Contract AY 4329.](https://reader035.fdocuments.net/reader035/viewer/2022062516/56649e205503460f94b0c602/html5/thumbnails/5.jpg)
Specific rain attenuation
![Page 6: A Study into the Theoretical Appraisal of the Highest Usable Frequencies RA Contract AY 4329.](https://reader035.fdocuments.net/reader035/viewer/2022062516/56649e205503460f94b0c602/html5/thumbnails/6.jpg)
Power levels for oscillators
500 GHz 1,000 GHz 1,500 GHz
.01
0.1
1
10
Mill
iwatt
s
x2
x3
x4, or x5
cascaded multipliers
100
Upconverted power
Fundametal power
BWO tubes
Available Output Power
Diode multipliers
Downconverted power
Photonic mixers
Gunns, (amplifiers)
![Page 7: A Study into the Theoretical Appraisal of the Highest Usable Frequencies RA Contract AY 4329.](https://reader035.fdocuments.net/reader035/viewer/2022062516/56649e205503460f94b0c602/html5/thumbnails/7.jpg)
typical multiplier source
Phase Lock
Harmonic Mixer
x N
Waveguide Coupler
Fundamental Oscillator
Frequency Multiplier
Output Power
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receiver performance
500 GHz 1,000 GHz 1,500 GHz
3
6
9
12
No
ise
Fig
ure
15
Available Receiver Performance
FP diode mixer
Receiver Nooise Figure
Amplifier technology
SHPdiode mixer
Superconducting mixer
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Schottky diode mixer at 200 GHz
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Important systems features
• Frequency range 100 to 1000 GHz and near infrared; bandwidth galore!
• high gain but compact antennas ( G ~ 50 dB; D=0.2m at 200 GHz)
• near field can be large; 266m at 1000 GHz for D=0.2m
• Restricted power levels; < 100 mw
• All scenarios are line of sight links or reflected paths
• RF safety level 100W/m2 in this frequency range could cause problems for very small antennas due to high flux density
• best performances on short paths with high gain antennas
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System evaluation methodology
• RF powers and noise figures were shown in previous slides
• antenna sizes were chosen to be small and practical for low cost production
• C/N ~11 dB (Eb/No =8 dB using QPSK modulation, achieves a BER of 1 in 10^4 allows error free channel with coding)
• clear air margins include gaseous absorption
• additional margins for rain, fog and scintillation were calculated to determine systems availabilities
![Page 12: A Study into the Theoretical Appraisal of the Highest Usable Frequencies RA Contract AY 4329.](https://reader035.fdocuments.net/reader035/viewer/2022062516/56649e205503460f94b0c602/html5/thumbnails/12.jpg)
Typical performance for a LoS link with data rate ~ 600 Mbps
margin and fade levels for a 2 km path length
-10.0
0.0
10.0
20.0
30.0
40.0
50.0
100 200 300 400 500
frequency (GHz)
dB
clear airmargin
0.1% ITU-Rrain
0.01% ITU-Rrain
0.01% rainLOWTRAN
fog 200mvisibility
0.01%scintillations
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Clear air margin as a function of link length
clear air margin as a function of link length
-50
-40
-30
-20
-10
0
10
20
30
40
50
100 200 300 400 500 600 700 800 900 1000
frequency (GHz)
marg
in (
dB
)
1 km
2 km
5 km
10 km
![Page 14: A Study into the Theoretical Appraisal of the Highest Usable Frequencies RA Contract AY 4329.](https://reader035.fdocuments.net/reader035/viewer/2022062516/56649e205503460f94b0c602/html5/thumbnails/14.jpg)
Fixed wireless access
• Data rates to users are between 2 and 10 Mbps each way; implies a base station down link rate of ~100 Mbps
• BFWA operating above 100 GHz as a fill-in to enhance capacity of a lower frequency P-MP system with
– narrow sector base station antenna ~25 dB gain
– user terminals ~15 cm diameter (similar to 40 GHz BFWA)
– maximum range ~ 2 km
– availabilities from 99.9% to 99.99%
– Or MESH system with smaller antennas ~ 10 cm
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margin and fade levels for aMESH system with ~ 1 km path length
-10.0
0.0
10.0
20.0
30.0
40.0
50.0
100 200 300 400 500
frequency (GHz)
dB
clear airmargin
0.1% ITU-Rrain
0.01% ITU-Rrain
0.01% rainLOWTRAN
fog 200mvisibility
0.01%scintillations
![Page 16: A Study into the Theoretical Appraisal of the Highest Usable Frequencies RA Contract AY 4329.](https://reader035.fdocuments.net/reader035/viewer/2022062516/56649e205503460f94b0c602/html5/thumbnails/16.jpg)
SATCOM above 100GHz
satellite transmitter power and rain fading are major problems
![Page 17: A Study into the Theoretical Appraisal of the Highest Usable Frequencies RA Contract AY 4329.](https://reader035.fdocuments.net/reader035/viewer/2022062516/56649e205503460f94b0c602/html5/thumbnails/17.jpg)
Aeronautical satellite system
Margin from satellite to aircraft at 5 km height
-10.0
0.0
10.0
20.0
100 200 300 400 500 600
frequency GHz
dB
Margin (dB)
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Mobile and nomadic systems
• access point is mounted at lamp post height (America traffic light position) with a high gain antenna( 40 gain dB) which illuminates the road for 0.5 to 1 km
• the mobile has a steerable patch antenna (5 cm diameter)
• range is up to 1 km• data rate ~100 Mbps • path with line of sight path or limited number of
reflections• system applicable to urban streets, motorways and
railways• weather has minimal effect
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Mobile systems
margin and fade levels for a mobile/nomadic system at a range of 0.5 km
-10
0
10
20
30
40
50
100 200 300 400 500
frequency (GH z )
dB
clear air margin
0.1% ITU-R rain
0.01% ITU-R rain
fog 200 mvisibility0.01%scintillations0.01% rain(LOW TRAN)
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Gigabit/s indoor communications
• Access point in corner of the room (ceiling height) with ~15 dB gain (~ 900sector)
• user antenna is ~3 cm diameter, which needs to be pointed to acquire best signal
• range 100m (I.e. large exhibition hall)• inverse square law assumed; i.e. l-o-s or good reflected
path• raw data rate ~1 Gbps• user transmitter RF power flux density near the allowed
safety limit at the lower frequencies• ample margin up to 400 GHz
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Gigabit/s WiFi
Margins (dB) for Gbit ETHERNET
-10
0
10
20
100 200 300 400 500 600 700
frequency (GHz)
dB Margin (dB)
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Anti collision radar
• Antenna size ~7 cm (size of license disc)• range 5 to 100 m• must operate in worst conditions 200mmh-1 and 5 m
visibility fog• target cross section assumptions
– either spherical target with 0.5 m2 area (low return signal)
– or specular reflection from number plate with 10 dB loss (high return signal)
– integration time 1 ms (target remains quasi stationary)
• pulse length ~20 ns requires 50 MHz bandwidth• operates up to at least 500 GHz
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Anti collision radar
anti collision radar margins
-20.0
-10.0
0.0
10.0
20.0
30.0
40.0
50.0
100 300 500 700 900
frequency (GHz)
dB
margin forsphericaltarget withaveraging
margin forspecularreflection(noaveraging)200 mm/hr
fog 5 mvisibility
scintillations 0.01%
Series6
Series7
Series8
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Attenuation in Fog
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Free space optical systems (FSO)
• Available as commercial devices – operating on ranges from 100 m to several km
– data rates from 10 Mbps to 1 Gbps
• Operate in near infra red window (0.7 to 1 microns)• transmitter devices: lasers or LED• power limited by eye safety requirement• main operational problems
– beam wander due to turbulence
– cannot penetrate thick fog
– typical availabilities ~99%
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Free space optical systems (FSO)
FSO margin with fade levels in rain, fog and turbulent conditions
0
20
40
60
80
100
0.0 1.0 2.0 3.0 4.0
link length (km)
dB
rainattenuation(0.01%time)fog 200 mpath
typical FSOfade margin
scintillation0.01%
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Millimetre wave system limiting performance
margin for P-P at 100, 200, 300 & 400 GHz compared with rain and fog
-20
-10
0
10
20
30
40
50
0 2 4 6 8 10
link lenght km
dB
100 GHz
200 GHz
300 GHz
400 GHz
0.01% rain
fog at 300 GHz
![Page 28: A Study into the Theoretical Appraisal of the Highest Usable Frequencies RA Contract AY 4329.](https://reader035.fdocuments.net/reader035/viewer/2022062516/56649e205503460f94b0c602/html5/thumbnails/28.jpg)
Conclusions
• best performance obtained for short range systems with high gain antennas ; e.g. radar, MESH & short range devices up to 700 GHz (IR systems also)
• acceptable performance from LoS applications >1 km up to 5 km (up to 440 GHz) also useful for MESH applications
• gigabit distribution possible up to 300 GHz with personal networks and home networks limited to below 260 GHz
• poor performance with fixed satellite but could be used for niche market aeronautical satellites
• FSO systems have poorer performance in fog than millimetre wave systems in rain