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

Daniel Krebs mail at daniel-krebs.net
Tue May 12 14:14:17 CEST 2015


Hi Oleg,
> 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.

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.

Best regards,
Daniel Krebs

[1] 
https://openwsn.atlassian.net/wiki/download/attachments/688143/ieee802154-2006.pdf


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