Thanks for you reply, Tom. So what you mean is that gnuradio only use one symbol to do the time & frequency (including coarse and fine)synchronization, as well as CSI estimation, is that right?
You also said the coarse freq. offset estimation is slight different. Can you show me some references only related to coarse freq. offset estimation in gnuradio. Thanks in advance. Best, Kay 2013/4/15 Martin Braun (CEL) <martin.br...@kit.edu> > On Sun, Apr 14, 2013 at 03:57:31PM +0800, Yingjie Chen wrote: > > Hi guys, > > > > I have check the 802.11 standard before. It said the coase freq. > estimation is > > done in short preamble, and the fine freq. estimation is done in long > premable. > > However, to my best knowledge, gnuradio only uses one preamble for > > synchronization. So how are these two freq. estimation works done in one > > preamble. BTW, can anyone tell me the exact different between coase one > and > > fine one? Are they both related to the FFT bin aligning? > > > The OFDM stuff in GNU Radio has *nothing* to do with 802.11x. It's just > a more-or-less generic OFDM implementation. > > I very much so recommend reading the Schmidl & Cox OFDM sync paper [1]; > their algorithm is pretty much what is used GNU Radio. It also explains > the difference between coarse and fine frequency offset (short: coarse = > integer multiples of sub-carrier offset, fine=smaller than that). > > In the original paper, they suggest 2 symbols for synchronisation (of > time & frequency) as well as initial CSI estimation. This can also be > done with 1 symbol, which is done in the current OFDM stack. > > The OFDM work that was recently added can handle both 1 or 2 > sync-symbols; the estimation of the coarse freq. offset is slightly > different for these cases. > > However, this type of sync needs modification if you want to adapt it to > 802.11. > > MB > > [1] Schmidl, T.M.; Cox, D.C., "Robust frequency and timing > synchronization for OFDM," Communications, IEEE Transactions on , > vol.45, no.12, pp.1613,1621, Dec 1997 > > > > > -- > Karlsruhe Institute of Technology (KIT) > Communications Engineering Lab (CEL) > > Dipl.-Ing. Martin Braun > Research Associate > > Kaiserstraße 12 > Building 05.01 > 76131 Karlsruhe > > Phone: +49 721 608-43790 > Fax: +49 721 608-46071 > www.cel.kit.edu > > KIT -- University of the State of Baden-Württemberg and > National Laboratory of the Helmholtz Association > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
_______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
