[Tinyos-devel] RE: [Tinyos-help] shorter (cc2420/telosb) radio range in t2 compared tot1?

[Omprakash Gnawali]

About the scenario: If a packet is received by many nodes, a node will
have received packets from many nodes.

- om_p

> 
> Yes... though the scenario is reversed.
> When all nodes are sending broadcasts, and one basestation is receiving,
> that base station is receiving packets from *less number of nodes*.
> 
> thanks
> 
> - jpaek
> 
> 
> Omprakash Gnawali wrote:
> > I think he is talking about a shorter range and not lower
> > throughput. He says whenever he sends a broadcast packet, fewer nodes
> > receive that broadcast pkt in T2 than in T1.
> > 
> > - om_p
> > 
> >> Here's one possible explanation: the CSMA backoff changed between T1 and T
 *2.
> >>
> >> In T1, the CSMA backoff wasn't very fair, allowing one transmitter to
> >> possibly hog the channel.  The CSMA congestion and initial backoffs were
> >> flipped in T2, making the initial backoff longer and the congestion backof
 *f
> >> shorter.  This causes less throughput but an increase in fairness.
> >>
> >> This brings up a good point though: more energy is consumed in T2 to deliv
 *er
> >> the same amount of information because throughput is diminished. We should
> >> explore turning the radio to IDLE during CSMA backoff wait periods to see
> >> how that impacts energy consumption and throughput.
> >>  
> >> -David
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: tinyos-help-bounces at Millennium.Berkeley.EDU
> >> [mailto:tinyos-help-bounces at Millennium.Berkeley.EDU] On Behalf Of Jeongyeu
 *p
> >> Paek
> >> Sent: Tuesday, October 30, 2007 12:33 AM
> >> To: tinyos-help
> >> Subject: [Tinyos-help] shorter (cc2420/telosb) radio range in t2 compared
> >> tot1?
> >>
> >> Dear all.
> >>
> >> I am running a very simple test applications where
> >> 40 nodes are broadcasting packets every 10 sec,
> >> and a BaseStation node is listening to those packets.
> >>
> >> And I am receiving far less packets in t2, compared to t1,
> >> for (what I believe to be) the same application.
> >> So I was wondering whether anyone had experienced
> >> shorter radio range in t2 compared to t1.
> >>
> >> The exact scenario is, 40 telosb nodes,
> >> with & without 'CFLAGS += -DCC2420_DEF_RFPOWER=31',
> >> on an indoor testbed (http://enl.usc.edu/projects/tutornet/)
> >> where node 1~40 are sending broadcasts and node 10 is the BaseStation.
> >> I ran experiments several times, for several tens of minutes each time,
> >> and tried channel 23 and 26.
> >> Also, although I am new to T2, I have some experiences with T1.
> >>
> >> In T1, I receive packets from 15~20 nodes on average.
> >> In T2, I receive packets from 8~12 nodes on average.
> >>
> >> And the only guess that I can think of
> >> (assuming that I've done t1->t2 poring correctly)
> >> is shorter radio range in t2 compared to t1.... for some weird reason.
> >>
> >> is this possible?
> >>
> >> -- 
> >> Jeongyeup Paek
> >> Ph.D. student
> >> Embedded Networks Laboratory
> >> Department of Computer Science
> >> University of Southern California
> >> http://enl.usc.edu/~jpaek
> >> _______________________________________________
> >> Tinyos-help mailing list
> >> Tinyos-help at Millennium.Berkeley.EDU
> >> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
> >>
> >>
> >> _______________________________________________
> >> Tinyos-devel mailing list
> >> Tinyos-devel at Millennium.Berkeley.EDU
> >> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-devel
> 
> -- 
> 
> Jeongyeup Paek
> Ph.D. student
> Embedded Networks Laboratory
> Department of Computer Science
> University of Southern California
> http://enl.usc.edu/~jpaek