1. Bell-Spike Power Doppler Spectrum Model
November 2003
Bell-Spike Power Doppler Spectrum Model
Angelo Poloni and StefanoValle
STMicroelectronics
A. Poloni, S. Valle, STMicroelectronics

2. Outline Topic: Bell-Spike Doppler Spectrum Model
November 2003
Outline
Topic: Bell-Spike Doppler Spectrum Model
The formula is missing in doc “161”
Spike parameters should to be defined more explicitly in the document:
spike position (vehicle speed);
spike “bandwidth”;
relative power between spike peak and bell shape.
A. Poloni, S. Valle, STMicroelectronics

3. Bell-Spike Doppler Spectrum Model formula
November 2003
Bell-Spike Doppler Spectrum Model formula
Bell-Spike Doppler Spectrum formula is presently missing in the doc “161”.
We propose the following:
A. Poloni, S. Valle, STMicroelectronics

4. Spike position along the frequency axis
November 2003
Spike position along the frequency axis
Presently, fspike is set equal to 200Hz, independently of the carrier, but this approach has not a physical justification.
It is preferable to define fspike on the basis of the vehicle speed. Which is a reasonable vehicle speed? (41 or 90 km/h can be argued by assuming 5.25 or 2.4 GHz respectively)
Maximum Doppler Spread of Bell shape (fd) could be defined on the basis of the speed as well. We note that a very slight inconsistency is present in the doc where 3 and 6 Hz are proposed for 2.4 and 5.25 GHz; such values correspond to speed equal to km/h and km/h. Is it possible to define a unique speed for both carriers?
In this case the formula should be written as follows:
A. Poloni, S. Valle, STMicroelectronics

5. Spike “bandwidth” Spike “bandwidth” is set with the parameter C.
November 2003
Spike “bandwidth”
Spike “bandwidth” is set with the parameter C.
We assume the bandwidth equal to afspike where the amplitude is 10dB below the spike peak; by imposing
then C = 36/ a2.
The best value for the parameter a should be chosen on the basis of the available channel measurements.
As an example, the next slide shows the spike shapes for 0.02< a< 0.1.
A. Poloni, S. Valle, STMicroelectronics

6. Spike “bandwidth” B =10 a =0.1 a =0.02 November 2003 S(f) [dB]
f [normalized]
A. Poloni, S. Valle, STMicroelectronics

7. Relative power between spike peak and bell shape
November 2003
Relative power between spike peak and bell shape
B represents the relative power between the Bell Shape maximum and the Spike peak.
The best value for the parameter B should be chosen on the basis of channel measurements.
As an example, the next slide shows the spike shapes for 1dB< B< 10dB.
A. Poloni, S. Valle, STMicroelectronics

8. Relative power between spike peak and bell shape
November 2003
Relative power between spike peak and bell shape 3 6
B = 10
B = 4
B = 2
B = 1
a = 0.02
S(f) [dB]
f [normalized]
A. Poloni, S. Valle, STMicroelectronics

9. November 2003
Conclusion
It is worth to propose a formula for the Bell-Spike Doppler Spectrum Model in doc “161”.
A formula is proposed.
The formula parameters should be tuned on the basis of the available channel measurements.
A. Poloni, S. Valle, STMicroelectronics