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. <[email protected]>:
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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