Re: [Discuss-gnuradio] [GSoC] Co-Processors Update #7

[Jan Krämer]

Hey Alfredo,

cool stuff with the Turbo Code :)

If you want to read more on general turbo code principles I suggest Hanzo's Book on Turbo Codes /EQ
http://www-mobile.ecs.soton.ac.uk/comms/files/fec-book-updtd.pdf

Turbo Codes start at Page 21.

I implemented the 8-state RSC code from LTE as single MAP Decoder in my Master's thesis and I found this pretty helpful:
http://www.etsi.org/deliver/etsi_ts/136200_136299/136212/11.01.00_60/ts_136212v110100p.pdf

Coding starts at page 11.

Hope this can help you.

See you at GRCON!

-Jan

2014-07-25 7:02 GMT+02:00 Alfredo Muniz <address@hidden>:

Thanks for your response Tom. I've been told you are the one to talk to about LTE stuff.

On Thu, Jul 24, 2014 at 9:19 PM, Tom Tsou <address@hidden> wrote:

Any
thoughts on the next milestone?

Currently I have everything working on the DSP through a compiled program that I load onto the DSP from the ARM. I would now need to send data between the ARM and the DSP so that we can interface with GNU Radio. I have a couple of options MessageQ, Msgcom, and CMEM. The plan is to simply pass a pointer with all the log-likeihood ratios on the ARM side so that the DSP can process it and then get the pointer to the resulting hard decisions back to the ARM. Once I can test that this works the next step would be to get the data from GNU Radio.

On Thu, Jul 24, 2014 at 9:19 PM, Tom Tsou <address@hidden> wrote:

If you are sticking with LTE decoding, the outer portions of the
receiver (OFDM, precoding, etc.) are probably out-of-scope for this
project

Yeah I don't know much about LTE decoding. The TCP3d is capable of operating in three modes: LTE, WiMax, and 3GPP. If one is easier to work with on the DSP side than another please let me know as the TCP3d simply does turbo decoding. It takes in LLRs and outputs the hard decisions though it can also give other things like soft decisions.

On Thu, Jul 24, 2014 at 9:19 PM, Tom Tsou <address@hidden> wrote:

do you think it would be possible to attach and
manipulate the Bit Rate Coprocessor (BCP)?

The BCP operates through the same means as the FFTC using the QMSS and CPPI. It is definitely possible but I think I've spent enough time on it for this summer. I will definitely revisit this issue once I have something more substantial to present for the conference. 

On Thu, Jul 24, 2014 at 9:19 PM, Tom Tsou <address@hidden> wrote:

Those are just random thoughts. If you need captures, myself or some
of the other LTE folks can probably provide live (or canned) signals
at various test points.

Thanks. Any resources to understanding the DSP theory would be helpful and your recommendation on whether to pursue LTE, WiMax, or 3GPP. I'm hoping to be at the point where I need to produce live data sometime late next week. Thanks again!

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