Subject: [manet] Re:Interference in RF networks - advantages of low power transmissions

From: [email-masked]
Date: Fri, 12 Jul 2002 13:18:48 -0500

All,

Just joined the MANET discussion list this month & saw several threads
relating to transmit power & whether many large hops or more shorter hops
is better.

FYI, I thought I would present some of the things I have seen in the ad hoc
networks we have worked on here at Rockwell Collins.

As part of the DARPA Survivable Adaptive Radio Networks (SURAN) program in
the 1980s [itself a follow-on to the DARPA Packet Radio (PR) program in the
1970s], we looked at this issue.   I developed a routing protocol called
Least Interference Routing (LIR) and documented it in a paper called
"Spatial Reuse Through Dynamic Power and Routing Control in Common-Channel
Random-Access Packet Radio Networks" that I published as my PhD
dissertation at the University of Texas at Dallas in Aug 1988.  Included in
the paper are simulation results showing the increase total network
throughput and reduced average end-to-end delay arising from reducing total
interference across the network.  (The paper was also released to DTIC as a
SURAN Technial Note (SRNTN) and some early results were published as a
MILCONM paper.)

Since then, we at Rockwell Collins have gone through several generations of
packet radio type networks (most of which has not been published).  We have
seen the same results also for adaptive dyanmic TDMA networks as well as
for random access networks.  I have analyzed the performance under a
variety of traffic and topology scenarios out to 2000 nodes and see an
advantage to reducing interference.  A large advantage comes from the
increased frequency reuse in large networks.  In addition, because you
usually (but not always) lower your transmit power to reduce total network
interference, you also see an increase in average nodal battery life due to
the use of more numerous, but on average lower power tranmissions.

Jim Stevens
Principal Systems Engineer
JTRS Networks
Rockwell Collins
[email-masked]

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From: [email-masked]
Date: Fri, 12 Jul 2002 13:18:48 -0500

All,

Jim Stevens