Structural Health Monitoring Using Smart Sensors - ideals ...

Sender
Send a packet
• Sender sends a packet to the receiver.
• Sender keeps sending the packet until
acknowledgement packet is received.
Receiver
Acknowledge
• Receiver saves received parameters and
return acknowledgement packet
Figure 5.16. Simple block diagram of the reliable unicast protocol for short messages.
Sender
SendSMsg.send()
Pack parameters and data
(e.g., Destination, message
ID, data, etc. )
SendShortSubTask()
SendShortMsg.sendDone()
call TimerNotice.start()
Receiver
ReceiveShortMsg.receive()
Receiver stores received
parameters and data.
Acknowledge the sender
Signal received()
TimerShort.fired()
if acknowledged,
signal SendDone()
else
post SendShortSubTask()
ReceiveNoticeMsg.receive()
set flag as acknowledged
SendAckMsg()
SendShortSubTask()
Figure 5.17. Detailed block diagram of the reliable unicast protocol for short messages.
Sender
Inquiry
• Inquire of receivers whether they are ready
Send a packet
• Sender sends a packet to the receiver.
• Sender keeps sending the packet until
acknowledgement packet is received.
Receiver
Acknowledge
• Receiver saves received parameters and
return acknowledgement packet
Acknowledge
• Receiver saves received parameters and
return acknowledgement packet
Figure 5.18. Simple block diagram of the reliable multicast protocol for short messages.
Unicast
The sender transmits a packet, including the destination ID, source ID, message ID,
parameter, and commands. Until this packet is acknowledged, the sender continues to
transmit this packet. The receiver extracts information from the packet and sends an
acknowledgment back to the sender (see Figures 5.16 and 5.17)
The end of one round is difficult to judge, as explained in the reliable unicast protocol
for long data records. The same solution applies to short messages. The source and
message IDs for the last 15 rounds of communication are stored so that acknowledgment
can be sent even after the receiver is disengaged from this round of communication.
Multicast
The sender first transmits a packet including the receivers’ node IDs, as was the case
for the multicast communication protocol for long data records. Once all of the receivers
return an acknowledgment to the sender, the sender transmits a packet containing
parameters and commands. The receivers also acknowledge this packet. To judge the end
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