Navigation functionality in cars, airplanes, railways, and mobile phones is mostly optimized for on-the-move functionality. It assumes that the user of such services tends to exhibit movement from one place to another with time. This is classified as outdoor navigation, implying navigation done outside homes, offices, malls, and any place not confined to a building or large area.

This is where indoor navigation sets in. Although GPS and other positioning systems have high coverage and accuracy, they fail when you are indoors, in a mall, or a shopping complex; even airport lounges, stadiums, and office complexes because the radio signals from GPS transmitters cannot penetrate walls. Indoor navigation works in such places using techniques dissimilar to outdoor navigation; in short, there is no GPS for indoor navigation.

There are various implementations of indoor navigation, some using infrared techniques, some using radio signals (RFID), and another implementation using ultrasound. Companies like Visioglobe (http://visioglobe.com) offer an SDK for indoor navigational purposes. Another company WiFiSLAM—is building a Wi-Fi based solution. While the market for indoor navigation is quite big and the outlook for growth is very positive, the implementation and standardization is at a very nascent stage, partly due to the fact that a generic solution that fits all is not possible for indoor navigation. Also, interactive kiosks at malls, airports, and convention centers solve the problem of information management for visitors.