ing universities access to online training materials).
Declining interest in computing is
disheartening and must be addressed
for the future health of both the Canadian and the U.S. technology industries.
For industry, money and effort spent
today on education should be seen as
an investment in its own future.
Bill Bushey, New Paltz, NY
trickle algorithm Corrections
The article “The Emergence of a Networking Primitive in Wireless Sensor
Networks” on the Trickle algorithm
I coauthored in July 2008 had two errors:
Sun SPOT sleeps. The article’s description of the Sun SPOT platform
said SPOT sleeps by writing its RAM
contents to flash while requiring significant time and energy to do so. The
SPOT has an external RAM bank to
which it saves its internal processor
state when it sleeps and, by itself, does
not incur a significant cost. However,
SPOT wakeup requires tens of milliseconds to stabilize timing circuits
and restore processor state. The alternative, used in most simple sensor-node designs, is to require just a few
kilobytes of RAM and microcontroller
wakeup times of tens of microseconds.
This fast wakeup time allows nodes to
quickly check for network traffic while
spending less energy warming up to
perform the checks; and
Srcr mesh routing protocol. The citation for the Srcr mesh routing protocol
designed by John Bicket incorrectly cited Douglas S.J. De Couto’s MobiCom
2003 paper “A High-Throughput Path
Metric for Multi-Hop Wireless Routing”
when it should have cited John Bicket’s MobiCom 2005 paper “
Architecture and Evaluation of an Unplanned
802.11b Mesh Network.” The citation
for De Couto’s paper also incorrectly
listed the author’s name as Couto, D.D.
rather than as De Couto, D.
Please accept my apology for these
errors. I thank Randy Smith, as well as
Douglas De Couto, for pointing them
out.
Philip Levis, Stanford, Ca
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feBRuaRY 2009 | vol. 52 | No. 2 | CommunICatIons of the aCm
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