How to simultaneously tx/rx on usrp with OFDM?

GNU Radio
1

Hi,
Basically I want to do following things on one usrp node.

  1. receive packets from one other node
  2. relay the packets received
  3. transmit packets generated locally

So my idea is to get the packets through usrp_src and receive_path, then
put
the received packets and locally generated packets together into
payload, then
use send_pkts() to sendout packets through transmit_path and usrp_snk.

There are several problems I am facing now(sorry, I am not a good
programmer,
maybe they are silly questions):

  1. I am trying to use different threads to receive packets and transmit
    packets. Although I used “global killed” and “sys.exit(1)” to make sure
    threads exit when Ctrl-C pressed, it won’t abort to the command line.

  2. As I said I need to combine received packets and locally generated
    packets
    at transmitting, but I didn’t figure out how to achieve that. I am
    thinking of
    make a global variable payload_all[], and just throw every packets into
    it,
    then use send_pkts to transmit the payload while receiving packets from
    others
    in another thread. Is that possible?

  3. The blocks transmit_path and receive_path I think are both having
    only 1
    connector in the graph. Is there any easy way to connect these two
    parts? Or
    is there any other blocks that I can use to make this kind of
    connection?

Any related suggestion will be appreciated.

I posted my small test codes
online(http://www.sendspace.com/file/6n64co), if
you can take a look at it and give me some suggestion, that will be
awsome.

Thanks a lot.
Yan Wang

2

in another thread. Is that possible?

  1. The blocks transmit_path and receive_path I think are both having only 1
    connector in the graph. Is there any easy way to connect these two parts? Or
    is there any other blocks that I can use to make this kind of connection?

Any related suggestion will be appreciated.

Hi,

Have you had a look at gr_message_sink/source? I think they might be a
good substitute to the global “payload_all[]”.

Just my uninitialized and very quick thoughts…

BR
//Mattias

3

Yan Wang wrote:

then
packets
connector in the graph. Is there any easy way to connect these two parts?

have you look at the post that tim send? :

RE: Editing benchmark_rx.py for spectrum access

inside they do the tx and rx in one file but it is not OFDM. but it is
very
simple to change it to OFDM since it is build form benchmark file…
benchmark_dsa.py script:
https://cornet.wireless.vt.edu/trac/browser/vtcross/trunk/src/cognitive_engines/DSA_CE/examples/gnuradio-examples
(CROSS form VT-very nice)

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4

adib_sairi <adib_sairi yahoo.com> writes:

have you look at the post that tim send? :

RE: Editing benchmark_rx.py for spectrum access

inside they do the tx and rx in one file but it is not OFDM. but it is very
simple to change it to OFDM since it is build form benchmark file…
benchmark_dsa.py script:

https://cornet.wireless.vt.edu/trac/browser/vtcross/trunk/src/cognitive_engines
/DSA_CE/examples/gnuradio-examples

(CROSS form VT-very nice)

Thanks for you information.
I’ll check it out.