[Discuss-gnuradio] precise transmit scheduling: GNUradio state-of-the-art?

[Brad Karp]

[Re-sending, as prior post appeared not to hit the list...]

Greetings, all.

I should preface this question by confessing that I'm new to the USRP
hardware and the gnuradio software. My students and I have only just
started hacking on 4 USRPs with 2.4 GHz daughterboards here in
lab. We'd like to use the platform to build a MAC protocol prototype.

As I know has been widely discussed in the gnuradio community,
link-layer acknowledgements require fairly precise timing of
transmissions. For example, the receiver of a data packet must delay a
very short interval before sending an ACK for the packet received
(e.g., on the order of 50 us).

My question:

What's the state of the art in precise scheduling of transmissions for
gnuradio? I'm looking for building blocks I can use that will allow
fairly precise scheduling of packet transmissions despite the 10 ms
process scheduling granularity of Linux.

I've seen in the archives of this list that BBN's work on m-blocks
appears at least partly motivated by precise scheduling of
transmissions. And other list traffic suggests that m-blocks are
being more broadly adopted; e.g., mail from Eric Blossom suggesting
that he was enhancing the m-block code further, perhaps with the
eventual goal of merging m-blocks into the core gnuradio distribution.

Is the m-block implementation in a state where my students and I could
use the code to schedule packet transmissions in the MAC protocol
we're implementing?

Are there other implementations of precise packet transmit scheduling
anyone can point me to?

Many thanks,
-Brad