Re: [Discuss-gnuradio] anyone implement the Raleigh fading model/multi-path?

[Feng Andrew Ge]

Tom, in your email exchange with Richard Clarke on 29 Jan 2008, as shown below, it was mentioned that a multi-path channel model might be integrated into GNU Radio library. 
I am wondering whether this has happened or not?  If not, do you still have code written by Richard's student? If so, would you suggest ways that I can get a copy of the code.
The FTP that Richard set up is not accessible now. 

Thanks,
Andrew


Tue, 29 Jan 2008 23:20:24 +0000
Richard Clarke wrote:

Hi George,

I have had a Summer student doing some work on this (a year ago now). He implemented a GNU Radio module that can do Rayleigh channel simulation. He based it on a particular paper (I'd have to look it up) for the implementation. He verified the statistical performance of his implementation against the Matlab Rayleigh channel model and against theory and found it to be a close match. I'm not entirely convinced of the delayed multiple path aspects of the design/implementation but haven't had time to look into it further. In fact as it stands I believe the GNU Radio module (at C++ level) only handles a single flat fading path and doing multiple delayed paths is done at the python module level and which invokes multiple instances of the Flat fading Rayleigh C++ GNU Radio module. I'd welcome another set of eyes and someone more experienced than I am with GNU Radio to help finish off this potentially very useful addition to the GNU Radio code base.

Cheers
Richard

Richard,

That sounds great; please let us contribute it. We have a basic channel model in Python that implements an AWGN channel, but has a filter, which you can set the taps to do fading. It'd be nice if we could enhance this to implement a Rayleigh, and even Rician channel (Nakagami, too, for those of you who really care about this stuff). Sounds like your student did some version of Jakes' model. At least, that's where I'd start. I have this in Matlab from an old class project that I was going to see about resurrecting, but it'd be great to have it already implemented in GNU Radio.

Thanks!
Tom