[riot-devel] Implementing a new MAC protocol for IEEE 802.15.4

Oleg Hahm oliver.hahm at inria.fr
Tue May 12 14:28:39 CEST 2015


Hi Daniel!

> >PAN coordinators are only required for the beacon enabled mode in IEEE
> >802.15.4. 6LoWPAN, for instance, does not require this mode (I'm not even sure
> >if it is supported by the spec) and thus, there is no need for a PAN
> >coordinator or star topology.
> That's unfortunately not the case. Please refer to the specs [1] at Section
> 5.3, especially the second paragraph. According to the specification a PAN
> coordinator is always required, even in "Mesh" topology where it may get
> dynamically elected.

Ok, I was imprecise here. You still have a pan coordinator but it has another
role and it's not really important for the MAC protocol any more (if I'm not
completely mistaken). At least, it is not a single point of failure any more,
so I fail to see how this is a problem.
 
> It get's even better (5.5.2.3 Peer-to-peer data transfers):
> >In a peer-to-peer PAN, every device may communicate with every other
> >device in its radio sphere of
> >influence. In order to do this effectively, the devices wishing to
> >communicate will need to either receive
> >constantly or synchronize with each other. In the former case, the device
> >can simply transmit its data using
> >unslotted CSMA-CA. In the latter case, other measures need to be taken in
> >order to achieve synchronization.
> >Such measures are beyond the scope of this standard.
> As receiving all the time is no option because of energy consumption you
> need some kind of synchronization. but that's "[...] beyond the scope of
> this standard". Thank you IEEE.
> 
> That's why I don't aim to be compatible with IEEE 802.15.4-2006 in terms of
> the MAC-layer. Either I have a PAN coordinator or it advises me to do what I
> want.

Well, if the spec tells you to do what you want (inside the boundaries of this
spec), then you can to what you want and be still 802.15.4 compliant.

Cheers,
Oleg
-- 
Unix is user friendly... its just selective about who its friends are.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 819 bytes
Desc: not available
URL: <http://lists.riot-os.org/pipermail/devel/attachments/20150512/88f95aef/attachment.sig>


More information about the devel mailing list