Detecting Interference through Passive Observation

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Overview

Interference is the key phenomenon that differentiates wireless networks for wired networks. The problem of determining the interference pattern of a wireless network can informally be stated as follows - Given any subset of links in the network, what is the performance of each of these links when we try to  simultaneously send data across all of them? Knowledge of the interference pattern is a pre-requisite for solving a number of problems such as channel assignment, scheduling, resource allocation and admission control. However, most previous work either assumes that the interference pattern is already available or that it can be approximated using simple heuristics or models. Recent measurements on testbeds have shown that such heuristics do not perform very well. While it is indeed possible to accurately determine the interference pattern through measurements, such active measurements can be very expensive both in terms of network resources and time.

In this work, we present a novel algorithm to avoid this problem by inferring interference from passively observing the performance of existing traffic in the network. We have implemented this algorithm in both a simulator and a testbed and show that it can accurately determine the interference pattern for active links (that are currently sending data) within a minute. It works well without modifications for a wide variety of traffic and network scenarios including different types of radio channels and antennae.

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People

  1. Ananth Rajagopala Rao (ananthar <at> cs <dot> berkeley <dot> edu)
  2. Ion Stoica (istoica <at> cs <dot> berkeley <dot> edu)