Hi,
I am pleased to inform you that our group has designed a TDMA-based
MAC protocol, named "PRIME", and has added an implementation of it to
the 'contrib' directory as tinyos-1.x/contrib/prime.
This is a collision-free MAC protocol. In the test with the
'Chirp' program on 4 Mica2 motes sending packets at 1 packet/400ms,
the packet delivery success rate is 95%, 2.5 times higher than
the current CSMA-based MAC protocol.
Actually, the current implementation is a simplified version of the
PRIME protocol (The full implementation was programmed and tested on
Mica, not Mica2 motes). Thus it's called SPRIME. Though not as flexible
as the full implementation, SPRIME is likely to still suffice for most
of applications.
I am including a README file at the end of this email. You are welcomed
to find the up-to-date version of this file in tinyos-1.x/contrib/prime.
More documentation and a setup program that install/uninstall SPRIME
will be added as soon as I can.
Comments and suggestions will be much appreciated, and I will be more
than glad to provide support if you'd like to try the protocol with
your applications.
Best regards,
lin
--
Lin Gu
Department of Computer Science
University of Virginia
-----------------------------------------------------------
The README file -- for interested readers
-----------------------------------------------------------
PRIME Protocol
Introduction
============
PRIME (Period Reservation and Inter-Master Estimation) protocol is a
collision-free MAC protocol. It automatically detects interfering nodes
in a network and uses TDMA to coordinate network transmission, so as
to avoid collision.
SPRIME is a simplified version which supports static time-slot (super-slot,
in PRIME terminology) assignment. Though not as flexible as PRIME, it
still achieves good performance -- in a test with "Chirp" program on 4
motes, the packet delivery success rate is 95%, compared with a success
rate of 26.5% with CSMA.
Files
=====
To facilitate interested developpers to try and test, a working version
including all the supporting files is included in this directory. The
following files and directories are main part of the SPRIME implementation.
README This file
tos/system/GenericCommPRIME GenericComm configuraiton file that uses
SPRIME
tos/system/SPRIME.nc SPRIME component
tos/system/MsgPool.nc Message pool (memory mangement)
apps/Benchmark/Chrip.SPRIME Chirp applicaiton, using SPRIME protocol
apps/Benchmark/Chirp Chirp application, using the originial
CSMA MAC that comes with TinyOS
More documentation will be added as soon as I can.
Configuration
=============
Right now the default configuration of SPRIME is a 4-mote, consecutive
ID configuration. The parameters are defined as macros in SPRIME.nc.
(TODO: a configuraiton file will be used instead of macros in the program).
Installation
============
Copy the 'prime' directory and set the 'TOSDIR' environment variable to
the 'tos' directory in the 'prime' directory. (TODO: a setup program will
be provided later to configure the existing TinyOS to switch between
using SPRIME and the original CSMA MAC protocol)
Test configuration and results
==============================
A simple test has been done to assess the performance of SPRIME. Four
motes, mote 0-3, are uploaded with Chirp application and put close to
each other.
To run the tests, cd to apps/Benchmark/Chirp or
apps/Benchmark/Chirp.SPRIME and use the usual TinyOS build method
make mica2 install.<mote id>
to build and upload program.
To compute the packet delivery rate, use a 'GenericBase' program to listen
to the packets (you may want to modify the GenericBaseM.nc file to tally
the packets received).
Right now, the Chirp programs send 160 packets at the rate of 1 packet/400ms.
The reference result is as follows
CSMA MAC SPRIME
-------- ------
success rate 26.5% 95%
So the success rate is increased by 258%.
History
=======
To improve the network performance on the MAC layer, we originally seek
to apply piggybacked acknowledgement to improve reliability. It develops
to "AMConform", which is a reliable one-hop communication protocol supporting
most of the functionality in traditional data-link level communication --
sliding window control, duplicate removal, queuing, piggybacked
acknowledgement, and re-transmission for unicast communication. The platform
is TinyOS 0.6 on Mica mote.
In our experiment and development for tracking demo, the reliable data-
link level component does improve the performance dramatically (But at
least half of the enhancement seems to come from the buffering
functionality). The retransmission introduces delay and impose a burden
on the network when the bandwidth is in shortage. It still does not handle
the wireless communication well because it does not consider hidden-terminal,
asymmetric channel, wide interference range, and so on... Retransmission
also consumes energy.
As a result, in 2002, PRIME protocol is designed to provide predictable
bahavior without incurring much computation, bandwidth and energy cost.
It's main features include hidden-terminal and interference detection and
TDMA scheduling. The development is based on TinyOS 0.6 on Mica motes.
To make the PRIME protocol work with TinyOS-1.x and NesC, the code is
modified early this year (2003) and the functionality is trimmed to make
it easier to be ported to programs where AMStandard is used, hence the
SPRIME protocol.
Acknoledgements
===============
The current PRIME/SPRIME implementation is based on TinyOS. Thanks to all
the people from Berkeley and other groups for helping me in various
development issues.
Support and bug report
======================
Please feel free to contact me for questions, bug reports, suggestions, or
just talking.
Lin Gu
Computer Science Department
Univ. of Virginia
[EMAIL PROTECTED]
Tel: 434-249-3158
********************************************************************
Sept 10, 2003
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