We have recently developed a comm stack on Mica motes at USC/ISI and UCLA.
It has some useful features that people might want to use or take a look.
Following is a highlight of the new features in our stack.
1) Flexible architecture that allows people to easily build different
components at different layers. The nested header structure allows each
component to freely define its own packet formats and add its header
fields in packets from upper layers.
2) Clean separation of MAC and the physical layer (PHY) allows different
MACs can be built on the same PHY. The PHY can reliably and efficiently
handle variable length packets up to 250 bytes, and is robust to
back-to-back packet transmission.
3) S-MAC provides energy-efficient operations on radio
- Low-duty-cycle operation on radio -- trade off latency vs. energy
- Overhearing avoidance -- sleep when neighbors are talking
The measurement in S-MAC paper shows that a MAC protocol without any
sleeping consumes 2 - 6 times more energy on radio than S-MAC in
different traffic conditions.
4) Abundant features in unicast provided by S-MAC (similar to 802.11).
- RTS/CTS/Data/ACK -- Robust to collisions, hidden terminal problem,
data packet losses
- Fragmentation support for long messages
We compared robustness of our stack and Berkeley's stack (before the
nesC release) and found similar reliability out to the ranges of 18m
(with matched whip antennas on 400MHz radios in the hallway of ISI
building). The SEC/DED encoding allows the UCB stack to extend the
transmission range by 2m. When ISI stack works with SEC/DED encoding, it
obtains the same transmission range as UCB stack. The physical layer of
ISI stack can work with any of these codes: Manchester, SEC/DED and 4B/6B.
For details of our stack design, implementation, functionality comparison
with Berkeley's stack and some performance measurement, you can look at
the documentation at
http://www.isi.edu/scadds/papers/commstack.pdf
For the performance on energy savings, you can look at the S-MAC paper at
http://www.isi.edu/scadds/papers/smac_infocom.pdf
Thanks,
-Wei
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