Transcript
COST297 –HAPCOS-, University of York, UK, October 2006
A spectrum etiquette for future mixed HAP terrestrial cognitive radio systems with minimum transmit power guarantees
Pairoj Likitthanasate, David Grace, Paul Mitchell
Communications Research Group, University of York, UK
Presentation Overview System
scenario
Multistage CINR
outage probability
based spectrum etiquette
Interference
margin
Results Conclusions
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System scenario HAP
HAP coverage area
Base station
Terrestrial coverage area/ Combined coverage area Terrestrial
φ
Base station
17 km
θ
30 m 7k
m
x
30
km
x
User 6.5 m 10 km
Coexisting HAP and terrestrial base station scenario 3
System parameters TABLE 1 System parameters Parameter
HAP Terrestrial station station
Coverage Radius
30 km
7 km
Transmitter Height
17 km
30 m
Max Tx Power
10 dBW
10 dBW
Antenna Gain
3 dBi
7 dBi
Roll off rate
3.3
N/A
User Antenna Height
6.5 m
Side lobe level
-30 dB
Bandwidth
20 MHz
Frequency
5.75 GHz
Noise Power
-130.8 dBW
TABLE 2 The minimum threshold requirement for different modulation scheme in the WiMAX standard Modulation scheme
Minimum SNR threshold requirement (Trm)
BPSK
6 dB
QPSK
9dB
16QAM
16 dB
64QAM
22 dB
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Multistage outage probability
Normal stage path Intermediate stage path
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CINR based spectrum etiquette Adjust
transmitter power of a newly activated system
– such that the CINR level of the incumbent users is still above,or at least equal to the original modulation scheme threshold
CNR ≥ CINR ≥ Trm
P / Si
PS AS (ϕ ) AU (θ ) PLS − NF Trm = ASi (ϕ ) AUi (θ ) PLSi
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CINR based spectrum etiquette Terrestrial user signal level when newly HAP system is activated When applying CINR based spectrum to HAP Without applying spectrum etiquetteetiquette to HAP system system Decrease by Interfering signal from
Carrier to Noise Ratio (CNR)
HAP system (transmit at 10 dBW) 64QAM Threshold
Adjusted CINR (CINR scheme)
Adjusted by decreasing transmitter power of interfering system (HAP) based on CINR based spectrum etiquette Carrier to Interference plus Noise Ratio (CINR) 16QAM Threshold
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Interference Margin
Obtained through statistical method – Look at statistic interference level caused by the HAP system transmitting at a specify guarantee transmit power level -120 5 degree 10 degree 18 degree 25 degree
Interference (dBW)
-125 -130 -135 -140 -145 -150
0
10
20
30
40
50 Percentile
60
70
80
90
100
Used to control the level of interruption (the incremental outage caused by the newly activated system, P12) by selecting a particular percentile level of the statistic interference level
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Interference Margin
Example of calculating the interference margin – For the guarantee 0 dBW HAP transmit power at 99-percentile we get I' = -134.15 dBW and NF = -130.8 dBW (specified in system parameter)
– The new interference level (noise plus interference caused from HAP system) affecting the existing system is equal to
I' + NF = (-134.15 dBW) + (-130.8 dBW) = -129.16 dBW
– This new interference level is higher by 1.64 dB than the previous interference level.
The Interference Margin of 10o beamwidth user antenna for the guarantee 0 dBW HAP transmit power at 99 percentile level = 1.64 dB
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Interference Margin interference margin for CINR scheme depends on –The degree user beamwidth antenna –The guarantee HAP transmit power level –The level of percentile selected
Interference Margin (dB)
The
0 dBW 0 dBW 5 dBW 5 dBW
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guaranteed HAP Tx power at 99th %tile level guaranteed HAP Tx power at 50th %tile level guaranteed HAP Tx power at 99th %tile level guaranteed HAP Tx power at 50th %tile level
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5
0
5
10
15
20
25 30 Beamwidth (degree)
35
40
45
50
10
5
Results Outage probability of users with 64QAM 1
Without applying any spectrum etiquette (both transmit at maximum power level)
Outage probability
0.8 0.6
P01 TER P01 HAP P12 TER P02 TER P02 HAP
0.4 0.2 0
0
5
10
15
20 25 30 Beamwidth (degree)
35
40
45
50
1
Outage probability
With 0 dBW guarantee HAP transmit power and IM at 99th percentile
P01 TER P01 HAP P12 TER P02 TER P02 HAP
0.8 0.6 0.4 0.2 0
0
5
10
15
20 25 30 Beamwidth (degree)
35
40
45
50
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Results Outage probability of users with 64QAM 1
With 5 dBW guarantee HAP transmit power and IM at 99th percentile
Outage probability
0.8 0.6 P01 TER P01 HAP P12 TER P02 TER P02 HAP
0.4 0.2 0
0
5
10
15
20 25 30 Beamwidth (degree)
35
40
45
50
1
With 5 dBW guarantee HAP transmit power and IM at 50th percentile
Outage probability
0.8 0.6 P01 TER P01 HAP P12 TER P02 TER P02 HAP
0.4 0.2 0
0
5
10
15
20 25 30 Beamwidth (degree)
35
40
45
50
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Conclusions
A spectrum etiquette ensuring a guaranteed minimum transmit power level for a newly activated HAP system is discussed.
The interference margin has been introduced to control the level of interruption to an incumbent terrestrial system.
The interference margins depend on system parameters. – user antenna beamwidth – the minimum guarantee transmit power level – the percentile level
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Contact Details Pairoj
Likitthanasate
– Email: – Tel: – Fax: Website
[email protected] +44 (0)1904 432310 +44 (0)1904 432335
for more information on HAPs
– www.elec.york.ac.uk/comms/haps.html
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