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From: | Marcus Müller |
Subject: | Re: [Discuss-gnuradio] ofdm frequency offset |
Date: | Wed, 24 Jun 2015 11:08:16 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 |
Hi zs, this reminds me very much of OFDM radar technologies, as your problem boils down to finding a good estimator for the spectral properties of your OFDM frame as well as the time it reached you. I think you should have a look at chapter 3, "OFDM Radar Algorithms" of [1]; you might find that considering the unknown timing being a result of the time it took a OFDM signal to reach you (and hence an effect of range) a useful approach. You can find some shorter information on the accuracy of these estimates in [2]. The difference in the algorithms described in [1] and your problem is that you don't a priori know the transmitted signal -- you'll have to figure that out by using something like S&C to receive and decode the OFDM symbol prior to "clean" reconstruction; you could then use the parameters (range == timing, doppler == frequency) that the radar estimators give you to model the symbol like you received it, and subtract it from your incoming signal. Of course, the mistakes you make when decoding the incoming symbol will have an influence on the accuracy of your estimates. Best regards, Marcus [1] Braun, Martin. OFDM Radar Algorithms in Mobile Communication Networks. Diss. Karlsruhe, Karlsruher Institut für Technologie (KIT), Diss., 2014, 2014; http://nbn-resolving.org/urn:nbn:de:swb:90-388921 [2] Braun, Martin, Christian Sturm, and Friedrich Jondral. "On the single-target accuracy of OFDM radar algorithms." PIMRC. 2011.; http://www.cel.kit.edu/download/PIMRC2011_BraunSchuSturmJondral.pdf On 06/24/2015 10:29 AM, zs wrote:
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