Is there a project which implements half-duplex communications?

Hello, GNU Radio users,

Very long time ago, USRP 1 was not suitable for half-duplex
communications
because USB 2.0 interface is too slow to achieve it.
But now, there are USRP embedded and gigabit ethernet supporting USRP
series.
In my opinion, thus, half-duplex communications might be achievable
nowadays.

I am curious that there is a project which implements half-duplex
communications.
If there is, how many USRPs, daughterboards and antennas are used for
each
node?
Can I find such a project in pybombs?

In my guess, a half-duplex communication application can be built from
both
USRP sink and source being placed in one flow graph.
But I have no idea of the rest of the flow graph. Should the flow graph
open loop or closed loop?
Is there a special configuration or tweak on USRP or GNU Radio required
to
achieve half-duplex communications?

I apologize if my question sounds quite vague.

Regards,
Jeon.

Hi Jeon,

Yes, of course these things have been doable for quite some time – not
very much because the latency of the buses went down, but more because
the USRPs learned to use command times, which means that you could
instruct the USRP to start to receive and transmit at sample-accurate
times, so to hide the latencies.

By now, there’s quite some standards implemented. gr-mac, formerly
pre-cog, is one of the frameworks you could build upon.
Bastian B. has actually developed multiple working transceivers:
Have a look at gr-iee802-11 (working WiFi implementation) an
gr-iee802-15-4 (Zigbee); they do work pretty well.

Best regards,
Marcus

Jeon,
Also check out
http://wp.me/p55sJw-2v
software based half duplex burst PSK modem which can operate using a
single USRP, file loopback, or other SDR
-Tim

Dear Tim and Marcus,

Thank you very much.

I’ll take a look at those projects.

Regards,
Jeon.

2015-07-01 0:03 GMT+09:00 Tim [email protected]:

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