Indoor localization has been an active area of research for several years. Especially as an enabling technology for location based services, indoor location support is of high interest for many business cases as well as for emergency/security scenarios. Location sensing represents a core component of ambient computing architectures, smart-environments and ubiquitous/pervasive computing architectures. The proliferation of wireless technologies, mobile computing devices, and the Internet has fostered a growing interest in location-aware systems and services. Many applications need to know the physical location of objects. Over the years, many systems have addressed the problem of automatic location- sensing. Triangulation, scene analysis, and proximity are the three principal techniques for automatic location-sensing.
The main reasons, why indoor location based services are yet not commonly deployed in a broad scale are high cost, complexity, administrative difficulties, security issues and weak accuracy. Most solutions are neither affordable for location based service providers, nor for their possible clients or customers. One of the most well known location-based systems is the Global Positioning System (GPS), a satellite-based navigation system made up of a network of 24 satellites placed into orbit. GPS is widely used to track moving objects located outdoors. However, GPS, as it is satellite dependent, has an inherent problem of accurately determining the location of objects located inside buildings. Different approaches have been proposed and tested for their effectiveness and utilities in order to achieve the ability to locate objects within buildings.
Our goal is to implement a prototype indoor location-sensing system using easily accessible wireless devices so that we can make use of existing infrastructures. At present, there are several types of location-sensing systems, each having their own strengths as well as limitations. Infrared, 802.11, ultrasonic, and RFID are some examples of these systems. After a thorough comparative study of these technologies, the results reveal that there are several advantages of the RFID technology. The no contact and non-line-of-sight nature of this technology are significant advantages common among all types of RFID systems. All RF tags can be read despite extreme environmental factors, such as snow, fog, ice, paint, and other visually and environmentally challenging conditions. They can also work at remarkable speeds. In some cases, tags can be read in less than a 100 milliseconds. The other advantages are their promising transmission range and cost effectiveness.
LANDMARC is a location-sensing prototype system based on RFID technologies. Since RFID is not designed for location sensing, the purpose of our prototype indoor location-sensing system is to investigate whether the RFID technology is suitable for locating objects with accuracy and cost-effectiveness. The proposed approach has been discussed with reference to the sensing elements used as well as the pros and cons of the approach.