Talk:Rayleigh fading

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Untitled[edit]

I'd like to the see analytic functions plotted for the Rayleigh fading plots -- maybe as a function of doppler spread. I've looked in Goldsmith's Wireless Comm for an example, but there is none :(

--adam

Which plot do you have in mind. Some of them have analytic functions, while some of them are results from stochastic simulations.

I would like to see different simulation models presented, dealing not only with Rayleigh distributed amplitud gain, but also phase distorsion and time spreading. I have seen several used in practice. Are there some standard method? I would also like to see more details on how to simulate Rician fading. Mange01 01:03, 29 November 2006 (UTC)[reply]

LCR and other spatial statistics[edit]

Level crossing rate and other spatial stats in this article are relevant only for omnidirectional propagation and therefore do not apply to general Rayleigh channel. As such I think they should be removed from this article. Pls comment.

Danielcohn 18:05, 14 November 2007 (UTC)[reply]

What do you mean by a 'general Rayleigh channel'? It strikes me as pretty obvious that LCR etc are relevant to a treatment of Rayleigh fading. Splash - tk 23:32, 21 November 2007 (UTC)[reply]

LCRs are relevant. The particular LCRs shown in this article are only valid for a particular subset of Rayleigh channels, namely omnidirectional channels. Directional fading will present totally different LCRsDanielcohn (talk) 22:46, 26 November 2007 (UTC)[reply]

PDF of Rayleigh[edit]

The wiki article on the Rayleigh distribution defines the PDF as

f(x|\sigma )={\frac {x\exp \left({\frac {-x^{2}}{2\sigma ^{2}}}\right)}{\sigma ^{2}}}.

The same formula is in Rappaports "Wireless Communications" book. Isn't there a two missing in the presented formula? Like the following:

p_{R}(r)={\frac {r}{\Omega }}e^{-r^{2}/2\Omega },\ r\geq {}0

Am i missing something? —Preceding unsigned comment added by 137.226.156.17 (talk) 16:46, 27 February 2008 (UTC)[reply]

Accuracy of Jakes Model[edit]

I've just been reading 'Jakes Fading Model Revisited' by Dent, Bottomley & Croft as referenced in the article and I've noticed several discrepencies to say the least with regards to the model investigated there and the model presented here on the wikipedia page.

First thing that is not so much a discrepency as such, the original α_n value in the unmodified model is not mentioned, a is no the same as α_n as stated in the letter reference. The original model's α_n is defined as 2πn/N, where N is the number of scatterers (M in the wiki article).

The equation itself for R(t,k) is also written in a user non-friendly way whereas it is represented much more nicely in the letter. The summation term should be the second addition rather than the first to remove confusion to people like myself. Looking at the 2πf_d terms in the article, would it not be more appropriate to specify these as angular frequencies ω_n instead? Also the 2 root 2 normalisation constant would probably be best shown as a K and then later given an example value of 2 root 2.

Last thing (for now), the definition of f_n appears to be that for angular frequency which is denoted by ω in my part of the world.

I'm a newbie to both this wikipedia thing as well as wireless models so I could be completely wrong, hence the possible confusion, but if someone can have a look and at least half agree with me then I'd be happy.

Regards, Theclem54 (talk) 07:58, 21 May 2008 (UTC)[reply]

Butterworth filter as the replacement of Jakes Model[edit]

Hi to all!

I've read in ^[1]^[2] that based on Butterworth filters approach is more realistic alternative for classical Jakes model. For example for LEO can be used the following filter:

- filter order: 10

- filter type: passband

- cut-off frequencies: 30 and 300 Hz

Python implementation:

from scipy import signal

b, a = signal.butter(10, [30, 300], 'bandpass', analog=True)
w, h = signal.freqs(b, a)

However, I have no strong confidence how and where this can be included to the article and should be included or not... Maybe, experts in wireless can comment my suggestion. Thanks for your time and labor! Kirlf (talk) 21:09, 11 July 2020 (UTC)[reply]

References

^ Loo, C. "Further results on the statistics of propagation data at L-band (1542 MHz) for mobile satellite communications." [1991 Proceedings] 41st IEEE Vehicular Technology Conference. IEEE, 1991.
^ Perez-Fontan, Fernando, et al. "S-band LMS propagation channel behaviour for different environments, degrees of shadowing and elevation angles." IEEE transactions on broadcasting 44.1 (1998): 40-76.

[1] Loo, C. "Further results on the statistics of propagation data at L-band (1542 MHz) for mobile satellite communications." [1991 Proceedings] 41st IEEE Vehicular Technology Conference. IEEE, 1991.

[2] Perez-Fontan, Fernando, et al. "S-band LMS propagation channel behaviour for different environments, degrees of shadowing and elevation angles." IEEE transactions on broadcasting 44.1 (1998): 40-76.

[1]

[2]