[manet] collision detection in TDMA-based ad hoc networks

[Leon Martin <leon70m at yahoo.com>]

Hi everyone,

I'd like to know the existence of some mechanisms for
detecting collisions in TDMA-based ad hoc networks.

The time is slotted (therefore TDMA). 

There is no centralized controller (e.g. base station,
cluster head, etc.).

I assume each node has only one radio, and when it
transmits it can't receive. As a result, if the signal
sent by a node collides with another signal, the node
can NOT detect the collision by itself. Its neighbors
can, however. 

There are some complications if we rely on the
neighboring nodes to detect the collision. First, if
we consider the capture effect (i.e., if the ratio of
the signal powers is big (or small) enough one of them
can be decoded), collision at one node does not
necessarily mean collision at another node because the
ratios of the signal powers will be different due to
the difference in node locations. Second, if a
collision occurs at one of the neighboring nodes, the
node can not decode the signal (packet). But, the
failure in decoding could be caused by other reasons
such as failure in synchronization. 

It seems to me, the only information the neighbors
have is the aggregate signal power of the collided
signals and the fact that no signals are decoded (if
we do not consider the capture effect). What can we
get out of this information?

Thanks.

- Leon

  

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com 

_______________________________________________
manet mailing list
manet at ietf.org
https://www1.ietf.org/mailman/listinfo/manet