• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 54 subscribers
  • Views 827 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

802.15.4 Acknowledge Frame : Is it a Unicast or Broadcast frame?

Ashwin Nair
Prodigy 160 points
Other Parts Discussed in Thread: CC2538

Hi,

I have 3 nodes(CC2538) in my network ( All of them are in the same RF Channel).

Two of them (say node A and B) belong to the same PAN whereas the third one(node C) is on another PAN.

I am sending a 802.15.4 data frame, with the ACK REQUEST bit set in the Frame Control Field , from Node A to Node B. Since AUTOACK enabled, Node A receives back an ACK from Node B immediately after sending the data frame.

However I also noticed that node C also received the same ACK Frame from Node B even though it didn't send a message. Why is this so?

The following are my queries:

  1. Is the ACK frame a broadcast frame to all nodes in the same RF Channel?
  2. Is there something to be done in the transmit frame population to change this behavior? 

Thanks,

Ashwin

  • 0
    Prodigy 160 points
    It appears that since the ACK frame does not have any parameters in the Frame Control Field, nodes have no way to filter the packets.
    The solution has been specified in the user guide.
    " To block reception of these frames effectively, use the ACCEPT_FT2_ACK bit of the FRMFILT1 register to control the expected receipt of acknowledgment frames:
    • Set the ACCEPT_FT2_ACK bit of the FRMFILT1 register after successfully starting a transmission with acknowledgment request, and clear the bit again after the acknowledgment frame is received or the time-out is reached.
    • Otherwise, keep the bit cleared."

    Ashwin