IMC '05, 2005 Internet Measurement Conference Abstract
Pp. 305310 of the Proceedings
Estimation of Link Interference in Static Multi-hop Wireless Networks
Jitendra Padhye, Sharad Agarwal, and Venkata N. Padmanabhan, Microsoft Research; Lili Qiu, University of Texas, Austin; Ananth Rao, University of California, Berkeley; Brian Zill, Microsoft Research
We present a measurement-based study of interference among links in a
static, IEEE 802.11, multi-hop wireless network. Interference is
a key cause of performance degradation in such
networks. To improve, or to even estimate the performance of these
networks, one must have some knowledge of which links in the network
interfere with one another, and to what extent. However, the problem of
estimating the interference among links of a multi-hop wireless network
is a challenging one. Accurate modeling of radio signal propagation
is difficult since many environment and hardware-specific factors
must be considered. Empirically testing every group of links is not
practical: a network with nodes can have links, and even if we consider only pairwise interference, we may have to potentially test
pairs. Given these difficulties, much of the previous work
on wireless networks has assumed that information about interference
in the network is either known, or that it can be approximated using
simple heuristics. We test these heuristics in our testbed and find
them to be inaccurate. We then propose a simple, empirical estimation
methodology that can predict pairwise interference using only
measurements. Our methodology is applicable to any wireless network that
uses omni-directional antennas. The predictions made by our methodology
match well with the observed pairwise interference among links in our
22 node, 802.11-based testbed.
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