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doc.: IEEE 802.11-03/839r1 Submission November 2003 A. Poloni, S. Valle, STMicroelectronicsSlide 1 Bell-Spike Power Doppler Spectrum Model Angelo Poloni and StefanoValle STMicroelectronics (angelo.poloni@st.com, stefano.valle@st.com)angelo.poloni@st.comstefano.valle@st.com
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doc.: IEEE 802.11-03/839r1 Submission November 2003 A. Poloni, S. Valle, STMicroelectronicsSlide 2 Outline Topic: Bell-Spike Doppler Spectrum Model –The formula is missing in doc “11-03-0161” –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.
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doc.: IEEE 802.11-03/839r1 Submission November 2003 A. Poloni, S. Valle, STMicroelectronicsSlide 3 Bell-Spike Doppler Spectrum Model formula Bell-Spike Doppler Spectrum formula is presently missing in the doc “11-03-0161”. We propose the following:
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doc.: IEEE 802.11-03/839r1 Submission November 2003 A. Poloni, S. Valle, STMicroelectronicsSlide 4 Spike position along the frequency axis Presently, f spike is set equal to 200Hz, independently of the carrier, but this approach does not have a physical justification. It is preferable to define f spike on the basis of the vehicle speed. Which is a reasonable vehicle speed? (41 or 90 km/h can be argued by assuming 200Hz @ 5.25 or 2.4 GHz respectively) Maximum Doppler Spread of Bell shape (f d ) 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 carriers @ 2.4 and 5.25 GHz; such values correspond to speed equal to 1.3500 km/h and 1.2343 km/h. Is it possible to define a unique speed for both carriers? In this case the formula should be written as follows:
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doc.: IEEE 802.11-03/839r1 Submission November 2003 A. Poloni, S. Valle, STMicroelectronicsSlide 5 Spike “bandwidth” Spike “bandwidth” is set with the parameter C. We assume the bandwidth equal to f spike where the amplitude is 10dB below the spike peak; by imposing then C = 36/ The best value for the parameter should be chosen on the basis of the available channel measurements. As an example, the next slide shows the spike shapes for 0.02<
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doc.: IEEE 802.11-03/839r1 Submission November 2003 A. Poloni, S. Valle, STMicroelectronicsSlide 6 Spike “bandwidth” =0.02 =0.1 B =10 f [normalized] S(f) [dB]
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doc.: IEEE 802.11-03/839r1 Submission November 2003 A. Poloni, S. Valle, STMicroelectronicsSlide 7 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< 10dB
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doc.: IEEE 802.11-03/839r1 Submission November 2003 A. Poloni, S. Valle, STMicroelectronicsSlide 8 Relative power between spike peak and bell shape 3 6 B = 10 B = 4 B = 2 B = 1 = 0.02 f [normalized] S(f) [dB]
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doc.: IEEE 802.11-03/839r1 Submission November 2003 A. Poloni, S. Valle, STMicroelectronicsSlide 9 Conclusion A formula for the Bell-Spike Doppler Spectrum Model in doc “11-03-161” is needed. A formula is proposed. The formula parameters should be tuned to conform with the available channel measurements.
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