Hi everybody, I'm working on implementing Schedule-based MAC protocol and I apply FTSP for time synchronization (use telosb mote). I use AMSend/ActiveMessageC interface to send and receive messages. Timestamp is made before sending message (or after receiving message as well) by using the command 'call LocalTime.get()'. And then, the receiver can calculate timeOffset = Global time - Local time However, the value of timeOffset is changed very much with each message, so the estimated global time is not correct. This error can be the timestamp problem. Please help me if you have any experience on this. It's very urgent. Some more questions: 1. How can I make timestamp at the moment before the message is sent to environment (close to physical layer as possible to reduce delay)? 2. Whether the AMSend interface performs RTS/CTS or senses the channel before sending the message Because each node is assigned slot for sending DATA message, so there is no need to use RTS/CTS. But for other type of message, it needs RTS/CTS to compete the channel. How can I do this? 3. Because it can use software/hardware Acknowlegment by default. How can I add some information into ACK message or disable both software and hardware ACK to use my own ACK?
Thank you very much! Best regards, Bin -- View this message in context: http://old.nabble.com/Timestamp-problem-tp33544786p33544786.html Sent from the TinyOS - Help mailing list archive at Nabble.com. _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
