title: Robust and Efficient Localization Techniques for Cellular and Wireless Sensor Networks
Creators: name: Khan, Haseebulla M.
Publisher: name: Old Dominion University Libraries
Year: 2005

description: Localization in wireless networks refers to a collection of tasks that, collectively, determines the location of a mobile user, striving to hide the effects of mobility from the user and/or application. Localization has become an important issue and has drawn considerable attention, as many applications including E-911, cargo tracking, locating patients, location-sensitive billing, etc., require knowledge of the location of user/objects. It was realized, quite a while back, that extending emergency 911-like services (E-911) to continually growing mobile population is one of the extremely important localization applications. The bulk of the proposed solutions to emergency location management in wireless environments are either reactive in nature or else rely on GPS-enabled devices. While GPS-enabled devices will become ubiquitous in the future, at present the use of GPS in highly accurate emergency location management and for low-cost cellular and sensor networks is unsuitable. Unfortunately, GPS does not work well in poor atmospheric conditions, the very conditions under which emergency situations are likely to arise. We propose a simple, robust and energy efficient localization techniques for cellular and wireless sensor networks. The first part of the thesis deals with a novel, proactive, lightweight and GPS-free scheme for providing high-quality location management for GSM based cellular networks. In a nutshell, our philosophy is that most of the task of user location is best left to the end user whose cell phone is quite capable of monitoring its location by cleverly exploiting beacons from neighboring base stations along its trajectory. This protocol is lightweight as it involves slightly overloading with the currently performed signaling. We present a robust trilateration algorithm which uses a technique known as ratio method to determine the location of mobile user using received signal strength (RSS). We then present an adaptive and predictive localization algorithm (APLA) which improves the accuracy of RSS, even under high user mobility.

The second part of the thesis proposes a novel, proactive and efficient scheme for providing localization in wireless sensor networks (WSN). Sensor nodes have some unique characteristics and properties that make the development of application nontrivial. They are limited by power, communication, memory and processing capabilities. GPS-based location techniques are not suitable for small, low cost and energy limited sensor nodes. Most of the known distributed location techniques introduce large errors and are not energy efficient. Although many algorithms and protocols have been proposed for traditional ad hoc-networks, they are not suitable for WSN due to their unique characteristics and properties. We propose an efficient proactive scheme to estimate the location of all sensor nodes in WSN. It is efficient as only single anchor node is sufficient to estimate the location of sensor nodes, where a minimum of three anchor nodes are required in a traditional method. Also, the proactive nature of the scheme reduces the unnecessary transmissions between sensor nodes, thereby saving energy. Most of the time sensor nodes are in proactive listening mode, making all location calculations locally and transmit the location information, only if required. We also present a course-grained localization technique, though not accurate, which provides alternate methods to localization in WSN.