There are no backoffs when transmitting an acknowledgment.  Even if the ack
is transmitted instantaneously to the receiver, it still takes time to
download and process the acknowledgment from the RXFIFO.  

 

The ack wait period was chosen experimentally in an environment with
multiple transmitters.  The more transmitters, the more likely the ack
reception will be delayed by some significant amount.

 

-David

 

 

 

  _____  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Jun
Sent: Friday, June 13, 2008 1:41 PM
To: renjie huang
Cc: tinyos-help@millennium.berkeley.edu
Subject: Re: [Tinyos-help] cc2420 transmission delay ( backoff times)

 

I think it's mainly due to software-ACK and the congestion backoff mentioned
by Phil.

Jun

On Fri, Jun 13, 2008 at 12:10 PM, renjie huang <[EMAIL PROTECTED]>
wrote:

i have a question. Why do CC2420 need to wait for hardware ACK for such a
log time? It should be very fast.

On 5/28/08, Jongkeun Na <[EMAIL PROTECTED]> wrote: 

On Wed, May 28, 2008 at 2:06 AM, salvatore galati <[EMAIL PROTECTED]>
wrote:

ack wait time of 256 jiffies = 3,84 msec


isn't one jiffy 32us? if so, the ack wait time should be 8.192ms.

-- 
Jongkeun 

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-- 
Renjie Huang
Sensorweb Research Laboratory 
http://sensorweb.vancouver.wsu.edu/
Washington State University 
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