Hi Avi, I'm not quite sure what *exactly* you're looking for, i.e. if you're really after the EM algorithm to find a MAP / ML estimate of the channel coefficients, or whether you just want that channel estimate.
I really like the gr-adapt [1] module of channel estimators, especially for its good documentation and examples, including recursive least square estimation. My estimation theory is a bit weak on that front, and I can't really tell you from the top of my head how EM compares to RLS etc. What I do know is that such algorithms typically make no guarantees on convergence rate¹; generally, Eigenvalue-based methods² behave more gracefully, and if I'm not completely mistaken, Karel's RLS belongs in that category. What's the reason you're asking for this? I'm not aware of EM being a common method for channel estimation, and from scrambling together my bits of random measurement theory/estimation theory knowledge and assembling the courage to say something about a field that I don't remotely feel confident talking about: you'd need to come up with a "coefficient likelihood function", something that takes in a very high- dimensional vector as argument, and which you iteratively improve with incoming data; that's basically a maximum likelihood parameter estimator in every iteration step? Feels like if you put knowledge into that ML step, you end up with a different form of parametric estimators. Cool stuff! But, and that's a honest question: why? Best regards, Marcus [1]https://github.com/karel/gr-adapt ¹ in fact, I'd expect that thing to only guarantee converging on a *local* minimum of error, not to the *global* one ² so-called spectral estimators, with "spectrum" as in "set of Eigenvalues", not so much as in "frequency domain". On Wed, 2018-11-21 at 10:50 +0200, Avi Caciularu wrote: > Does anyone know where I can find implementation of that? > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
