Evaluating the Importance of Concurrent Packet Communication in Wireless Networks
Dongjin Son, Bhaskar Krishnamachari, and John Heidemann
USC/Information Sciences Institute
Abstract
Nearly all wireless media-access (MAC) protocols are designed today
with the very conservative assumption that concurrent transmissions
should be prevented, because sender-receiver pairs within radio range
sending on the same channel will corrupt each other's communication.
While recent work has suggested that channel capture effects can be
significant in reality, this paper presents the first systematic study
to quantify the impact of these effects on the ability to have
concurrent communications among two sender-receiver pairs that are
within range of each other. We first derive a simple decision rule to
determine when such concurrent communication is possible while
minimizing transmission power. Through a comprehensive set of
realistic simulations, we then systematically quantify the feasibility
of concurrent communication with and without transmission power
control as many radio and environmental parameters vary, including
node position, mean and variance of path loss,
signal-to-interference-plus-noise-ratio threshold ($SINR_\theta$) for
packet reception, granularity and range of transmission power
control. Our simulations show that often, 40-75% of the time
depending primarily on distance and location, two pairs of nodes can
communicate concurrently without loss even if both transmitters are
within the radio sensing range of both receivers. We can observe
large CTXable region with fixed transmit power, but dynamic power
control significantly improves concurrent communications. Finally, at
least one transmitter can almost always capture the channel in the
event of concurrent transmissions, so the cost of failed attempts to
CTX are minimal. We validate our simulations with testbed experiments
using MicaZ motes, confirming that concurrent communication is
possible to a very significant extent in real systems. These results
suggest that CSMA with RTS/CTS is overly conservative and there are
often gains to be realized by abandoning it.
Availability
This paper is available in several formats:
abstract web page with pointers and cites,
PDF,
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Copyright terms for this paper appear below.
Reference
- Son07a
-
Dongjin Son, Bhaskar Krishnamachari, and John Heidemann.
Evaluating the Importance of Concurrent Packet Communication in Wireless Networks.
Technical Report ISI-TR-639, USC/Information Sciences Institute, April, 2007.
<http://www.isi.edu/~johnh/PAPERS/Son07a.html>.
@techreport{Son07a,
author = "Dongjin Son and Bhaskar Krishnamachari and John Heidemann",
title = "Evaluating the Importance of Concurrent Packet Communication in Wireless Networks",
institution = "USC/Information Sciences Institute",
year = "2007",
number = "ISI-TR-639",
month = "April",
keywords = "sensornets, 802.11, rts-cts, concurrent
packet transmission",
url = "http://www.isi.edu/~johnh/PAPERS/Son07a.html",
pdfurl = "http://www.isi.edu/~johnh/PAPERS/Son07a.pdf",
}
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© 2007
Last Modified: August 2009