[Tinyos-help] about 802.15.4 ack

[nevermore]

Hi!
Now i know tinyos has mechanism to handle the duplicate packet,thank you
very much!

All the best!

2009/4/28 Razvan Musaloiu-E. <razvanm at cs.jhu.edu>

> Hi!
>
> On Tue, 28 Apr 2009, 林枫 wrote:
>
>  Hi,Razvan ME:
>>     Thank you for you reply.I have read the file CC2420PacketC.nc, but i
>> can not find any code that handles this problem.In 802.15.4-2006,there is
>> no
>> content to
>> handle this problem too.I have read some implementation of 15.4 written in
>> c,they just ingore this problem and let the upper layer to handle the
>> duplicate frame(maybe process it once more ).I wonder why they do not
>> handle
>> this problem in the mac layer.I mean i can keep a table in the mac layer
>> to
>> record the sequence number of different source node , if the sequence
>> number
>> of the incoming frame is the same as the sequence number of last frame
>> from
>> the source node,we discard it.Maybe it costs too much,but if we do not do
>> anything  there will be errors.
>>
>
> One more place to look at is this one:
>        tinyos-2.x/tos/chips/cc2420/unique
>
> The table that keeps track of the sequence numbers is in UniqueReceiveP.nc.
> :-)
>
> --
> Razvan ME
>
>
>  2009/4/28, Razvan Musaloiu-E. <razvanm at cs.jhu.edu>:
>>
>>>
>>> Hi!
>>>
>>> On Tue, 28 Apr 2009, 6lowpan wrote:
>>>
>>>  Hi everyone.
>>>
>>>>
>>>> In 802.15.4,when a receiver receives a frame from a sender ,it will send
>>>> back an ack.If the sender fails to receiver the ack,it will send the
>>>> frame
>>>> with the same sequence number again.
>>>>
>>>>
>>> The retransmission happens only if the PACKET_LINK is enabled.
>>>
>>>  I can not find how the receiver handles this frame in the document.Does
>>> it
>>>
>>>> discard it or process it once more?
>>>>
>>>>
>>> The code is in tinyos-2.x/tos/chips/cc2420/packet.
>>>
>>> All the best!
>>> Razvan ME
>>>
>>>
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