Thanks for the response, Mariano! I will take a look at the CCA code you've
included for contiki mac.
Do the CSMA modes in 802.15.4 typically sense in a way to back off to
802.11? Just curious on what you've found on typical implementations.
On Fri, Sep 16, 2011 at 7:11 AM, Mariano Alvira <m...@devl.org> wrote:
> On Fri, Sep 16, 2011 at 06:58:46AM -0700, George Nychis wrote:
> > Hi all,
> >
> > I was wondering what the status of the clear channel assessment is on the
> > RedBee. I am noticing that 802.11 slaughters reception, although I think
> the
> > 802.11 signal should be strong enough to carrier sense.
> >
> > I am wondering if it is: 1) 802.11 not backing off to the zigbee
> transmissions,
> > or 2) zigbee not backing off to 802.11.
> >
> > I understand there is a fairness issue here, and I can imagine (1) not
> > occurring because of ZigBee only transmitting in a subset of the
> frequency
> > space that 802.11 is sensing. But, I was wondering more of what the
> status of
> > (2) is.
> >
> > I looked through some of the code and found the maca code and mentions of
> CCA
> > flags, but the "TODO" says CCA.
>
> I have CCA basically sorted out, but what exacly to do with it is an
> open question for a lot of different implementations.
>
> If one wished to implement one of the CSMA modes specified in
> 802.15.4, for instance, I have enough knowledge about how the CCA
> hardware works to get them through that development.
>
> I'm currently working on fixing ContikiMAC for the mc1322x, which also
> requires a CCA check. That code is here:
>
>
> http://git.devl.org/?p=malvira/contiki-2.x.git;a=shortlog;h=refs/heads/contikimac-oldcfg
>
> In cpu/mc1322x/lib/maca.c and cpu/mc1322x/contiki-maca.c you'll find
> CCA code.
>
> -Mar.
>
>
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