[Tinyos-help] Queue and time sync

[Muhammad Azhar]

Hi all,

   If a number of motes are sending data to the root every 10 secs, does the 
root need some sort of Queue to enqueue the messages, so that no messages 
are lost?  'Coz when I did something like this, there were a few instances 
when the motes were not sending messages to the root, although it'd come 
back later.  The motes were places statically, so is it possible that the 
link quality is affecting the transmission?  Or is it simply because I 
didn't put my messages in queue, thus, some messages were not processed by 
the root?

   Also, are there any recommended articles on simple time synchronization?  
I've read RBS and TPSN, but I don't really know how to implement the former 
while for the latter, I do not have any idea on lowering the granularity of 
the clock as well as time stamping the packets at the RFM layer instead of 
the application layer.  Although there are codes for the latter, I think 
they're really quite complex.  I'd like to implement a really simple time 
synchronization.
   By the way, what exactly does "local clock" mean?  Is it just referring 
to the timer value?  In that case, wouldn't all "local clocks" start from 
zero?  If it is referring to a specific time, then how do we implement this? 
  In fact, is it possible to do this if my root is permanently attached to 
the USB port of the PC where it is always receiving data?  Also, if we want 
to use a reference clock, does it mean that other motes do not necessarily 
need a "clock"?

   I'm really quite lost on implementing time sync.  Furthermore, I can't 
seem to find pseudocodes on this too (the only codes I found were 
implemented by Saurabh G. which I really find too complex).  But most 
importantly, I need to know what local clock is referring to.  Many thanks 
for your patience.

Regards,
Azhar