Re: [6tisch] 6top-interface-04

[Qin Wang <[e-mail]>]

Hi Tero,
You raised a good question, i.e. how to define a cell for broadcast in 6top.
(1) I think 6top needs a way to define broadcast cell. A sender can not assume or know if the message transmitted in a TX cell will be received by all other nodes even if its nodeAddr is set to oxffff, because sender cannot know others TSCH schedule. Thus, there must be some bitmap in the sender to tell TSCH scheduler whether the TX cell is a Unicast cell or Broardcast Cell, i.e. neighbors are listening or not sure.
(2) It is indeed that IEEE80.15.4e uses LinkType to indicate if the cell is for Advertisement, but does not say it cannot be used to broadcast other message as you said. Thus, I wonder if 6top, as a sublayer, can take advantage of LinkType to define the broadcast cell, and let the content of broadcast come from broadcast Queue, EB or other broadcast message.
What do you think?
ThanksQin
 


     On Wednesday, September 30, 2015 2:16 PM, Tero Kivinen <[e-mail]> wrote:
   

 Qin Wang writes:
> In the IEEE802.15.4e, there are two attributes related with a cell, i.e.
> LinkOption and LinkType. LinkOption indicates TX, RX, Shared, or Timekeeping;
> and LinkType indicates Normal or Advertising. According to my understanding,
> if the attributes of a cell are set as LinkOption = TX and LinkType=
> ADVERTISING, then the cell can be used as Broadcast cell. Make sense?

LinkType of ADVERTISING means that this link is used to send enhanced
beacons out. There can be other broadcast traffic going out than
enhanced beacons, so I do not think you can only claim that
ADVERTISING links are broadcast cells. 

    ADVERTISING = 1, and indicates the link may be used to send an
    Enhanced beacon.

and

    ADVERTISE links may be used to send Enhanced beacons as the
    result of the MAC receiving a MLME-BEACON.request.

I would assume that broadcast link is something that is defined so
that all devices are listening that, i.e. where the listeners have RX
bit on, and nodeAddr for the sender is set to 0xffff. I do not think
linkType has anything to do with that, but as 6top-interface-04 does
not define what broadcast link/cell means, it is impossible to say.
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