An improved congestion-aware routing mechanism in sensor networks using fuzzy rule sets

Abstract

Congestion-free routing of packets across a Wireless Sensor Network (WSN) is an important issue to be addressed for quick response applications such as disaster management, healthcare systems, traffic control, etc. The existing routing algorithms have been developed by mainly considering hop-count leading to a gap in addressing congestion problem in the routing process. Congestion during routing leads to increase in packet drops, increased energy consumption and delay in delivery of packets at the sink node. Therefore, it is necessary to propose an optimal congestion aware routing mechanism that considers network parameters such as congestion level and energy dissipation in addition to hop count factor. Hence in this paper, a traffic prudent framework called Congestion Aware Routing using Fuzzy Rule sets (CARF) has been proposed for handling excess traffic conditions by identifying the non-localized node paths, there after adding them to the existing localized node paths and selecting a more reliable and a congestion alleviated path to sink node using fuzzy rule prediction. This results in reducing packet drops and increasing energy utilization. The proposed framework CARF is organized into two operational segments namely 1) Multiple Path Identification by positioning non-localized nodes and 2) Congestion Mitigated routing of data packets to sink node. First operation employs the Positioning of a Non-Localized node algorithm that is used to compute the unknown coordinates of a sensor node thereby utilizing them to form more packet transmission paths in addition to the existing paths. The Point In Which Side (PIWS) hop count-based geometric method is utilized here for finding non-localized nodes in the sensor network. Second operation uses an Enhanced Fuzzy-based Congestion Mitigation (ECFM) algorithm for estimation of congestion level in nodes using fuzzy rule sets by considering incoming data packets per second, bandwidth size and path reliability. This CARF framework has been simulated using NS-2 testbed. Depending on the two major network characteristics such as path reliability and congestion level, a network path is chosen for routing data packets. From the experiments conducted in this work, it is proved that the proposed CARF mainly alleviates congestion, besides reducing energy cost and interference such as shadowing and attenuation.