> > OK Cool - OFDMA is new to me - I'll read up on it. > Hi David,
Consider this: with carrier per user instead of timeslot per user, you don't have the distance limitation that TDMA introduces. Also, the code is slightly more simple as it doesn't require tx burst timestamps and hardware to support it. I've spent a week digging into the GSM implementation of the osmo-trx software, and it's not straightforward to do with a Gnuradio flowgraph. Reception is easy but transmission is harder, and if you aim to maximize capacity you have very little time to fit into a slot. Also, with OFDMA the PAPR issue is offset by narrower receive bandwidth, unlike TDMA where you take the SNR hit for all channels at the same time. I think it's worth looking into, I may even have a demo by the end of the year if the holidays are uneventful. > There are carefully tested Octave and C 4FSK modems that meet > theoretical performance in codec2-dev that you can use as a reference. > With open source, implementation complexity isn't a huge issue - someone > only has to build it once. mFSK isn't that much harder than 2FSK, and > certainly easier than a PSK modem. > I'd argue that 2FSK with convolutional encoding is way easier to implement than 4FSK with same. But that's just my experience with Gnuradio and may reflect my laziness. I'd say there are few people writing code on this sort of stuff in the open, but I've seen open source code for Yaesu's C4FM and the demodulation is much more complex than generally believed. Meanwhile people tend to disregard open source projects as inferior, so getting traction won't happen soon. Best regards, Adrian ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
