Localization and tracking of a mobile node using WiFi

Abstract

Localization of a mobile node is an interesting and emerging field now-a-days. To properly achieve true autonomy, mobile node must be able to determine where it is in relationship with a global frame of reference and it must be able to do so with a minimum of interaction from human operators and impose as few constraints on its surroundings as possible. However, localization has been described as “fundamental problem in robotics”. This problem arises due to the fact that vehicular motion of any kind is imperfect, no matter how great the precision is, the uncertain nature of mobility and perception requires that advanced probabilistic inference techniques be applied to minimize error. Every sensing technique is also subjected to the same error as in case of motion. Hence the difficulty level in solving the problem, is reinforced. No sensor is perfect therefore, various methods have been applied to the localization problem including sonar, laser range finders (which bounce a highly focused beam of light off, of a nearby object and measure the time it takes to return) and stereoscopic camera. In recent years, however, a growing interest has been shown in the use of radio-frequency signals to accomplish localization. Advances in wireless communication have enabled mobility of personal computing devices equipped with sensing and computing capabilities. This has motivated the development of location-based services (LBS) that are implemented on top of existing communication infrastructures to cater for changing user contexts. To enable and support the delivery of LBS, accurate, reliable and real time user location information is needed. This thesis introduces localization system for tracking the position of mobile node, using received signal strength (RSS) in Wireless Local Area Networks(WLAN).The main challenge in WLAN positioning is the unpredictable nature of the RSS-position relationship. Existing system relies on a set of training samples, collected at a set of test points with known positions in the environment to characterize this relationship. In this work Wi-Fi signal is used to accomplish localization and tracking, which is not only result in localization and tracking, regardless of the positioning of different objects, but also enhances the ability to use relatively inexpensive hardware to solve a problem that requires expensive solutions. Wireless network identification card (NIC) is used to capture Wi-Fi signals (real time data) and received signal-strength indicators (RSSI) is used to infer relative distances and triangulate the most likely position of a mobile node.