Here's one possible explanation: the CSMA backoff changed between T1 and T2.
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 backoff shorter. This causes less throughput but an increase in fairness. This brings up a good point though: more energy is consumed in T2 to deliver 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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jeongyeup 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@Millennium.Berkeley.EDU https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help _______________________________________________ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
