Re: [Discuss-gnuradio] in-band signaling & dependent packets (i.e., ACK generation)

[George Nychis]

Brian Padalino wrote:
> A few questions:
>   - What is the current round trip latency for the in-band code?

To measure the round trip latency we used three USRPs... two in 
contention and a third monitoring.  The two in contention would exchange 
the channel back and forth by reading the RSSI value from the incoming 
packets.  To spare the details and cut to the chase, we measured the gap 
between the time the channel went idle, the contending node detected it 
was idle, and began transmitting.  This is essential measuring dependent 
packets and host-level carrier sense performance.

The average was 1.96ms and sdev 0.62ms.

>   - Have you tried synchronizing two different USRPs to each other over the air?

What do you mean by synchronizing?

>   - What is the minimum amount of turnaround time you're looking to achieve?

Tens of microseconds would be great... but I'm not sure if this is 
achievable?  Hundreds of microseconds would be decent :)

- George