Not the CC2420 asynchronous low power listening stack like
the one found in 2.x. Boomerang, that includes the time
synchronized functionality, uses 1.x-like syntax.
-David
On Tue, 20 Feb 2007 15:04:50 -0500
Jiakang Lu <[EMAIL PROTECTED]> wrote:
Hi all,
Is there any module that implements this CC2420 LPL
strategy on Tinyos-1.x? Have anyone written such a radio
stack?
Thanks.
Jiakang
David Moss wrote:
Asynchronous low power listening similar to the behavior
of B-MAC has been
introduced for the CC2420 radio in TinyOS 2.x. This LPL
CC2420 stack is not
B-MAC or X-MAC, by the way. The 'experimental' version
is still located in
tos/chips/cc2420_lpl, but a more reliable and robust
version can be found in
tinyos-2.x-contrib/rincon/tos/chips/cc2420_lpl. That
version is going to
get a few more features before getting put back into the
baseline.
The CC2420 LPL strategy is to use clear channel
assessments to determine if
a transmitter is nearby and modulating the channel. If
modulation is
detected with valid 802.15.4 data, the radio is left on
for a brief moment
to attempt to capture a packet. If a packet is received
successfully, the
radio is left on as long as communications are taking
place. After a few
moments of inactivity, the radio will continue to duty
cycle.
There isn't much literature on the design of the CC2420
radio stack. Maybe
I'll put something together sometime. Basically it's a
standard radio stack
though: A bunch of layers down the send branch, a bunch
of layers up the
receive branch, and a bunch of layers to control power.
Some layers can be
added and removed from the stack as needed.
The main reason LPL was not implemented for a long time
was because it was
impossible to implement B-MAC on the 2420 radio -
specifically, the radio
could not extend its preamble for a long duration of
time. A new strategy
had to be developed, and there were many people involved
with evolving the
CCA receive check strategy.
Moteiv's Boomerang features time sychronized CC2420
radio duty cycling,
which is much more efficient than the current
asynchronous CC2420 duty
cycling.
-David
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On
Behalf Of Antonis
Lambrou
Sent: Monday, February 12, 2007 10:27 AM
To: [email protected]
Subject: [Tinyos-help] CC2420 radio stack
I am currently conducting research for MAC protocols
designed for Wireless
Sensor Networks and I would appreciate some guidance
from tinyos-help.
In your FAQ you have the following answer for the MAC
design:
"Support for the CC2420 radio was introduced in TinyOS
1.1.7. The CC2420
uses B-MAC. However, the CC2420 radio does not have the
Low Power Listening
functionality; it does have the MacControl and
MacBackoff interfaces but,
again, the underlying functionality is not implemented."
If Low Power Listening is not implemented does that mean
that the radio is
listening constantly for incoming packets? What are the
reasons for not
implementing LPL on the CC2420 radio stack?
Where can I find more documentation on the design for
the CC2420 radio stack
on TinyOS? I have read so far the paper "Versatile Low
Power Media Access
for Wireless Sensor Networks", which describes the B-MAC
protocol, but as I
understand the protocol is slightly changed on the
CC2420 radio stack.
Thank you,
[EMAIL PROTECTED]
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