In the WSNA '02 paper, the paper states in section 6.1 that a sample is taken every minute over the course of a 24 hour period. If the sample is 10 bits and placed in a 25 byte packet, then we can send 20 samples per packet. This results in 72 packets required per day if sampling 10-bit samples once per minute.
In the current TinyOS structure (0.6.1), the packet is 36 bytes as defined by MSG.h. This means that there are 2 bytes for the address, 1 byte for the handler, and 1 byte for the group id; then there are 30 bytes for the payload and 2 bytes for the CRC. For a specific application, the packet length can be changed by modifying MSG.h, as was done in the Great Duck Island / Habitat Monitoring application. The new TinyOS (version 1.0) that uses nesc to be released this month has a radio stack that permits variable length packets. This means that multiple components or applications compiled into the same binary can send varied-length packets. -Joe -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of David Patnode Sent: Tuesday, September 10, 2002 10:16 PM To: [EMAIL PROTECTED] Subject: [Tinyos-users] Packet Structure & Sensor Data I have not found any specific information about this, so I'm asking here: Is there a defined packet structure? The original papers use a 30-byte packet, with a destination byte, handler byte, and 28 bytes of payload. Are there newer specifications? Also, in the Wireless Sensor Networks for Habitat Monitoring paper (http://www.cs.berkeley.edu/~polastre/papers/wsna02.pdf), in section 6-1, the authors indicate that for a 10-bit ADC sample of a light sensor & packet payload of 25 bytes, it requires 72 packets to transmit (using 10 bit samples) or 116 packets (transmitting 16-bit integers containing the 10 bit sample). I do not understand this. Are multiple ADC samples being transmitted? Is there processing being done on the samples to create some kind of image over time? I don't understand why a 10-bit sample requires 14,400 bits (72 packets * 25 bytes * 8 bits). What am I missing? Thanks in advance! David _______________________________________________ Tinyos-users mailing list [EMAIL PROTECTED] http://mail.Millennium.Berkeley.EDU/mailman/listinfo/tinyos-users _______________________________________________ Tinyos-users mailing list [EMAIL PROTECTED] http://mail.Millennium.Berkeley.EDU/mailman/listinfo/tinyos-users
