[Tinyos-help] tree level (hop count) information in CTP?

[Philip Levis]

On Oct 1, 2008, at 1:57 PM, Omprakash Gnawali wrote:

> On Wed, Oct 1, 2008 at 1:09 PM, Philip Levis <pal at cs.stanford.edu>  
> wrote:
>>
>> On Oct 1, 2008, at 12:22 PM, Hui Kang wrote:
>>
>>> The root can get the hop counter from getTHL.
>>> But how can a node infer the hop counter to root?
>>
>> It can't. CTP uses ETX, not hopcount, to measure distance to the  
>> root, and
>> it doesn't keep track of hopcount.
>>
>
> If ETX is 8, the maximum distance is 8 hops and looking at the minimum
> threshold for link ETX, one can also estimate the minimum distance.

Sure. But since the max link ETX is 6 (right?), that means it's 2-8  
hops. Not really that useful.

Given the very dynamic nature of a CTP tree, calculating how a node's  
hopcount is kind of tricky. It would just be a guess.

Phil