On Wed, 2006-01-11 at 09:18 -0600, Alfredo Quesada wrote: > Hi > > I'm trying to develop a multipath algorithm for sensor > networks and I need to simulate itself. Currently I'm > working with tossim, but I've found a problem: > It seems that packet collisions are not notified to > the "virtual motes", and even if your neighbours don't > receive the packet you always receive a SUCCESS value > at Send.sendDone. > > Is this usual at tossim? Is it working at the right > way? > > I'm showing messages when there's a problem at > Send.send time and also when not getting a successful > status at send ending, but it never happens. > > I'm using RadioCRCPacket as my radio component.
The result_t in sendDone does not indicate whether the packet it was received. It indicates whether the packet was sent (transmitted into the medium) successfully. Whether or not someone received it is an entirely different matter. In practice, early radio stacks generally didn't handle error conditions well and never passed FAIL. The 1.x CC2420 stack, because of the comparative complexity of the chip, took a different approach, and signals FAIL whenever it has the slightest hint that something might have gone wrong. But this is changing in more recent codes (e.g., 2.x). On the micaZ platform, there are some weird situations where the MCU never triggers a start of frame delimiter (SFD) interrupt, which indicates that a packet has begun to be sent on a CC2420 radio. So when it expects an SFD, the TinyOS 2.x stack starts a timer; if the SFD doesn't arrive in a reasonable period of time, then the timer fires, figures something is wrong, clears out the radio state and signals sendDone with an ERETRY. Phil _______________________________________________ Tinyos-help mailing list [email protected] https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
