Abstract-Outdoor navigation services have become ubiquitously available due to small handheld devices such as GPS enabled mobile phones or dedicated mobile navigation systems. Two main drivers were necessary in order to provide widespread location based services: Acquiring positioning information with a certain degree of precision and widespread (mobile) access to computer networks to use the position information with a large information basis such as the Internet. Envisioned is a future, where indoor navigation and location based services are used as naturally as outdoor location based services are now. To achieve this long term vision where users seamlessly navigate for example from work desk to departure gate at the airport and use location based services on the way, various challenges have to be solved.In this paper, these challenges and open issues are discussed. The paper proposes an architecture which abstracts from different mobile devices and localization technologies. Additionally, it sketches the use of indoor topology information to increase the accuracy of indoor localization. These two presented concepts form a basis for a transition period until standards for ubiquitous indoor location based services have emerged.

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This paper introduces two protocols for communication in infrastructure networks consisting of a central server, stationary basestations and mobile devices. Mobile devices use IEEE 802.15.4 to communicate with the basestations. Among other things, the proposed protocols differ in their location management and in the routing of downlink and uplink packets. Through extensive simulations the protocols are compared with the focus on latency and packet loss metrics. The strength of each protocol depends on the traffic pattern caused by an application. This paper concludes with a recommendation for the usage of each protocol.

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