[Likely SPAM] Re: [Tinyos-help] CC2420 radio stack

[David Moss]

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 <jl9jb at cs.virginia.edu> 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: tinyos-help-bounces at Millennium.Berkeley.EDU
>> [mailto:tinyos-help-bounces at Millennium.Berkeley.EDU] On 
>>Behalf Of Antonis
>> Lambrou
>> Sent: Monday, February 12, 2007 10:27 AM
>> To: tinyos-help at Millennium.Berkeley.EDU
>> 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,
>>
>> Antonis.Lambrou at ncl.ac.uk
>>
>>  
>>
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> 
>