Feasibility study of a WCDMA direct air-to-ground link in the UMTS ...
UMTS Link Budget Calculator
12
Label a b c d = a + b + c j q k m n = j + k + m + q r t = n + r e f g u v w x = d+t+e+f+g+u+v+w y = Prop(x) u
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Transcript of UMTS Link Budget Calculator
INITIAL PARAMETERS
System:Frequency:Bearer Rate:Coverage Probability - Cell edge:Cell loading:
LINK BUDGET (Uplink)
Labela Tx Power (dBm)b Tx Antenna Gain (dBi)c Cable and combiner losses (dB)
d = a + b + c EIRP Tx Power (dBm)
j Thermal Noise density (dBm/Hz)q Bandwidth factor (dBHz)k Noise Figure (dB)m Interference to thermal noise (dB)
n = j + k + m + q Interference Noise density N (dBm/Hz)r Average Eb/No (dB)
t = n + r Rx Sensitivity (dBm)
e Rx Antenna Gain (dBi)f Cable/Feeder Loss (dB)g Diversity Gain (dB)u Fading Margin - cell edge (dB)v Soft Handover Gain (dB)w Building/Car Penetration Loss (dB)
x = d+t+e+f+g+u+v+w Max Path Loss (dB)
y = Prop(x) COST 231 Cell Radius (km)
SHADOW FADING MARGIN (calculation)
Decay Law (n) Std dev of Fading Margin (dB)Std Dev / n
Coverage Probability - cell edgeu Fading Margin - cell edge (dB)
B8
Service defines the required Eb/No.
B9
Probability that the call quality in the cell edge will be maintained.
B10
This gives an indication of the proportion of simultaneous users in the system compared to the maximum number of users that could be supported.
B20
Effective Isotropic Radiated Power (dBm) EIRP = Tx Power + Tx Antenna Gain - Cable Losses
B22
k To: k is the Boltzmann constant and To is the temperature of the environment (290 K)
B23
Bn: Bandwidth factor in dBHz for required service. Depends on the user data rate.
B24
F: It is a measure of the amplifier noise.
B25
Maximum interference allowed over noise floor for system stability for the defined cell loading.
B27
N: N = k To F Bn, or in dB form: N = k To + F + Bn The interference to thermal noise must also be added to this parameter to account for noise produced by other users. Therefore, Interference Noise Density = Thermal Noise Density + Noise Figure + Bandwidth factor + Interference to thermal noise
B28
Depends on service and environment. Values are taken from ETSI with Turbo code modification. Includes diversity gain. Assumes 20 ms interleaving, Vehicular A.
B30
The required level of energy at the input of the receiver. Rx sensitivity = (Eb/No) + Interference Noise Density
B35
The fading margin used in this link budget is the one calculated from the confidence level at the cell edge. See calculation below for a more detailed explanation.
B39
Lp = EIRP - Rx Sensitivity - Fading Margin - Other Losses + Other Gains
B44
The fade margin allows for inaccuracies in the planning tool and the presence of slow fading.
B49
Standard deviation of the variation between signal level and median prediction.
B52
Probability that the call quality in the cell edge will be maintained.
B53
Fading Margin calculated from the above probability. This fade margin is more stringent than the one calculated from the confidence level in the whole cell area (below).
Coverage Probability - whole cellFade Margin - whole cell (dB)
CELL RADIUS FROM COST 231 FORMULA (calculation)
UE Height:
Antenna Correction factorUrban CorrectionSuburban correctionOpen Country Correction
BS Height (m)Path Loss (dB)Distance (km)
B55
Probability that the call quality in the whole cell will be maintained.
B56
This offset is calculated from the above probability, for the whole cell area. Calculations assume 15m BS height and no diffraction effects.
B59
COST 231 is only valid for frequencies from 1500 to 2000 MHz.
EXAMPLE LINK BUDGET SPREADSHEET*********************************
UMTS950649550
95.00
1.5
0.02 0.00
10.09 28.74
(blue indicates user definable parameters)
MHz (1500 - 2000 MHz)kbps%%
Urban Microcell Urban Macrocell****************** ******************
21.00 21.00 0.00 0.00 0.00 0.00
__________________ __________________21.00
-174.00 -174.00 48.06 48.06 4.00 4.00 3.01 3.01
__________________ __________________-118.93
2.20 3.80__________________ __________________
-116.73
18.00 17.00 -2.00 -2.00 0.00 0.00 -1.64 -1.64 5.00 5.00
-15.00 -15.00 __________________ __________________
142.08
3.12 4.04
Urban Microcell Urban Macrocell****************** ******************
3.44 3.57 1.00 1.00
0.29 0.28
%1.64 1.64
D16
21 dBm for handheld units. Up to 24 dBm otherwise.
D24
Vendor specific.
D34
Diversity gain modelled in link layer, therefore included in Eb/No figure.
D36
Usually from 2 to 5 dB. 5 dB figure is based on 50% correlation between fading channels.
1.00 1.0014.46 dB 14.46
m
dBdBdBdB
Urban Microcell Urban Macrocell****************** ******************
40.00 25.00142.08 139.48
3.12 4.04
D55
Use goal seek by changing cell below
D56
See cell above
Suburban Rural****************** ******************
21.00 21.00 0.00 0.00 0.00 0.00
__________________ __________________21.00 21.00 21.00
-174.00 -174.00 48.06 48.06 4.00 4.00 3.01 3.01
__________________ __________________-118.93 -118.93 -118.93
3.80 3.80__________________ __________________
-115.13 -115.13 -115.13
17.00 17.00 -2.00 -2.00 0.00 0.00 -1.64 -1.64 5.00 5.00
-12.00 -6.00 __________________ __________________
139.48 142.48 148.48
16.29 23.98
Suburban Rural****************** ******************
3.57 3.57 1.00 1.00
0.28 0.28
1.64 1.64
1.00 1.0014.46 14.46
Suburban Rural****************** ******************
25.00 25.00142.48 148.48
16.29 23.98
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