Improved accuracy of acknowledgement delivery by considering SNR

[tinyos-2.x.git] / apps / tests / TestSimComm / README

diff --git a/apps/tests/TestSimComm/README b/apps/tests/TestSimComm/README
index 9e7d2df1781bbda66faeaf0e3e25721443b68d97..30e4d7a15435564ff5ea3dd2d828fe6189f3b938 100644 (file)
--- a/apps/tests/TestSimComm/README
+++ b/apps/tests/TestSimComm/README
@@ -1,4 +1,4 @@
-TestTimer, 5/17/07 
+TestTimer, 5/22/07 
 
 This application tests the TOSSIM radio model by setting up a simple
 hidden terminal case. It checks whether packets collide correctly and
@@ -10,8 +10,9 @@ There are three test cases:
 
 test-equal.py: Tests whether two nodes that are hidden terminals
 cause collisions. The two nodes have equal signal strengths, so a
-collision should corrupt both packets. If one packet is lost,
-the other should be too.
+collision should corrupt both packets. If one packet is lost due to
+a collision, the other should be too. Note that packets can be 
+lost in the absence of collisions due to external interference.
 
 test-unequal.py: Tests whether two nodes that are hidden terminals
 cause collisions. The two nodes have signal strengths that differ
@@ -21,5 +22,12 @@ from node 1 is lost, the packet from node 3 should be as well. However,
 a loss from node 3 does not imply a loss from node 1, as it is
 stronger.
 
+test-asym.py: Tests whether asymmetric links can have high delivery
+rates but low acknowledgement rates. Checks that acknowledgements
+follow SNR curves properly. In this test, both 1 and 3 have high
+quality links (-60 dBm) to node 2, but the reverse links (2 to 1 and
+2 to 3) are much worse (-80 dBm). You should see packet deliveries
+like test-equal.py but few acknowledgements.
+
 Philip Levis