[USRP-users] [RFNoC] Listen Before Talking (LBT)

Felipe Augusto Pereira de Figueiredo zz4fap at gmail.com
Sat Oct 14 12:11:41 EDT 2017

Sorry, I've just noticed my last email did not include the USRP mailing

On Sat, Oct 14, 2017 at 12:30 PM, Felipe Augusto Pereira de Figueiredo <
zz4fap at gmail.com> wrote:

> Dear Michael,
> Thanks for your answers!
> However, I still have some questions.
> 1) Will this new block be connected to the crossbar as the other NoC
> modules? I'm asking it because you mention the block should have 2 input
> ports and 2 output ports, so I'm supposing they are all connected to the
> crossbar and will communicate through DMA.
> 2) As I understood, this new block would be placed between DDC and Host
> PC, and also, between DMA FIFO and the DUC block. I mean, the flow would
> be, DDC -> New Block -> Host PC and DMA FIFO -> New Block -> DUC, is my
> understanding correct?
> 3) Would the new data flow: DDC -> New Block -> Host PC add very high
> latency to the communication between USRP and Host PC, or it would not
> impact too much? Wouldn't it be better for new block to receive data from
> the DDC without being in the middle between DDC and Host PC?
> 4) Is there some trick to control the DMA FIFO reading or is it simple as
> done by other blocks connected to the crossbar? I've never worked with
> those kinds of FIFO...
> Thanks again and Kind Regards,
> Felipe Augusto
> On Fri, Oct 13, 2017 at 9:48 PM, Michael West <michael.west at ettus.com>
> wrote:
>> Hi Felipe,
>> That is absolutely possible to do in RFNoC and not very hard.  You simply
>> create a block that has 2 input ports and 2 output ports with one input
>> from the DDC, one input from the DMA FIFO, one output for the RX data back
>> to the host, and one output for data to the DUC.  All of your power
>> calculation and control logic sits in the block.  User registers can be
>> instantiated to control the threshold and any other dynamic parameters you
>> need.
>> Regards,
>> Michael
>> On Tue, Oct 3, 2017 at 1:42 AM, Felipe Augusto Pereira de Figueiredo via
>> USRP-users <usrp-users at lists.ettus.com> wrote:
>>> Dear All,
>>> I'm thinking of implementing LBT with RFNoC, however, after an initial
>>> study of the RFNoC framework I realized it would be hard to implement
>>> what I had in mind:
>>> Initially, I would start with a very basic approach:
>>> 1) Calculate the power received just after the DDC for every received
>>> packet
>>> 2) If the power is greater than a defined threshold I would disable
>>> the DUC from reading new IQ samples from the dmaFIFO. Disabling DUC
>>> would require a new output signal (DDC) and input signal (DUC).
>>> However, I think the approach with input/output signals would not be
>>> the best one but I don't really have better ideas as I'm quite new to
>>> RFNoC.
>>> Now comes the reason why I'm writing this email, I'd like to know if
>>> there is a better approach for this LBT implementation with RFNoC.
>>> Any hint will be very helpful!
>>> Thanks and Kind Regards,
>>> Felipe Augusto
>>> _______________________________________________
>>> USRP-users mailing list
>>> USRP-users at lists.ettus.com
>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
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