OK, I'll look at gathering up all relevant code and documentation and
see what hosting options I have at this end. When I've got this sorted
I'll post a link to the location of the files. In the meantime a little
additional detail, taken from some of the comments in one of the header
files.
It will be great to progress this module such that multiple delayed
paths can be implemented at the C++ level without requiring python to
handle the delays.
*------------------------------------------------------------------
/*
This class implements a flat Rayleigh Fading Simulator based on Christos
Komninakis work referred to in his paper "A Fast and Accurate Rayleigh
Fading Simulator" (http://www.ee.ucla.edu/~chkomn/). Some analysis has
been carried out by myself confirming that his algorithm is similar to
the Rayleigh model available within Matlab "rayleighchan()".
Inputs
- seed: the random channel seed (e.g. -115).
- fdT: Discrete Doppler Rate (small positive fraction, e.g. 0.001 -
0.2), where fd is the Doppler fade frequency and 1/T is the sample rate
of the channel. Note that the current implementation only supports
rational fractions of 0.2. To accommodate other values the IIR filter
needs to re-designed using Matlab (please reefer to the paper mentioned
above for details).
- pwr: the square root power of the resulting fading waveform (e.g. pwr
= 5 would produce a fading waveform with an output power of 25).
- flag_indep: Determines whether individual blocks processed by the
channel should be treated as independent blocks or as one continuous
block. 1 if blocks are independent, 0 if continuous across blocks.
Jonas Hodel
01/02/07
*/
*---------------------------------------------------------------
Cheers
Richard
(Please note: I have no control over the signature attached to the
bottom of this email, sorry! ;-)
George Nychis wrote:
Hi Richard,
This would be great! I have great use for this, and I'm sure many
others would too. Did he generate any documentation showing his
evaluation of his implementation, and any details of it? (like a
final research paper).
Could you make this code publicly available to the list so that we can
review its implementation and discuss integrating it in to the code
base? We could work on integrating the multiple paths in to the C++
block and making it flexible.
If you host it for us, it won't undergo just one set of eyes, but many
sets of eyes on the list :) But make sure to link to it, rather than
send an attachment because of list restrictions. Then we can put it
in a features branch within the SVN repository to work on it if needed.
Thank you!
George
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
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