ABSTRACT:In this paper a tool to estimate the interference between nodes and links in a live wireless network by passive monitoring of wireless traffic has been proposed. This tool proposes the use of multiple sniffers being deployed across the network to capture wireless traffic trace thus does not requires any controlled experiments, injection of probe traffic in the network, or even access to the network nodes. Using machine learning approach these traces help to infer the carrier-sense relationship between network nodes. We are also able to detect selfish carrier-sense behavior.Experimental and simulation results demonstrate that the proposed approach of estimating interference relations is significantly more accurate than simpler heuristics and quite competitive with active measurements. We use ns2 simulation to also validate the approach in a real Wireless LAN environment.
KEYWORDS: 802.11 protocol, hidden Markov model, MAC layer misbehavior, interference
I.INTRODUCTIONA Highly loaded network experiences a poor WiFi performance [1], [2]. In this work a technique to model and understand the wireless interference between network nodes and links in realistic WiFi network deployments is being presented. The goal is to achieve this without installing any monitoring software on the network nodes using a completely passive technique because any active measurement affects the network traffic. To achieve these goals, our approach uses a distributed set of "sniffers" that capture and record wireless frame traces. We then analyze the trace to understand the interference relations. This approach requires additional hardware for measurement, this can be viewed as a form of third-party solution. Such an approach is not new for example, DAIR [7], [8], Jigsaw [9], and Wit [10]. While these approaches provide many monitoring solutions, but do not provide any interference which is possible in the technique proposed.We are also able to detect the selfish behavior of the nodes . A selfish node can gain unfair share of the available bandwidth by manipulating different MAC protocol parameters, and can results in more collisions and can other transmitters to back off . We can detect the selfish carrier-sense behavior using the pairwise interference relationships discovered by the proposed technique which had been discussed only in one paper [11], that provides a limited solution using a nonpassive technique. Figure 1 Overview of the approach
II.SYSTEM MODEL AND ASSUMPTIONS