Today we have more and more different access technologies, which are available on the market. Therefore, the need for location-based service provision adopted to suitable networks is an important issues. Furthermore heterogeneous network interoperability across mobile, terrestrial and wireless network should be addressed in Next Generation Networks (NGN) too. Today, considerable open issues in standards are available and have to be addressed to realise all desirable features in NGN environment.
Significant technological advances are taking place in recent years in the areas of palm-sized computers and wireless communications, accompanied by an infiltration of the Internet in all aspects of our lives. Mobile Internet access accounts today for only a tiny proportion of the Internet users even though the number of mobile users greatly exceeds the number of Internet-users. However, it is forecasted that as early as 2003 almost half of the Internet population will consist of mobile access devices. By that time, a variety of different wireless network platforms with different properties, capable of transporting Internet traffic will be available. In addition, the turn of operators towards license-free frequencies and their eventual congestion will lead to the realisation of alternative dynamic network structures, namely Internet compatible, multi-hop, ad-hoc networks.
Consequently, a technology that allows the integration of available heterogeneous and homogenous networks into a single platform capable of supporting user roaming between them, while not interrupting active communications, will gain importance. This development will be assisted by the rise of new mobile devices capable of maintaining various access interfaces that will allow simultaneous connectivity over a range of providers and technologies. Internally, such devices will be able to distinguish between networks with individual properties and intelligently determine on a per flow basis, the most appropriate network. Finally, the emergence of a plethora of access devices will dictate the liberation of users from a single device (i.e. mobile phone) and allow mobility between devices even as the user is communicating.
The rapid growth of the mobile Internet user base has not been accompanied by an equivalent evolution in the corresponding products and services for mobile customers. Such services and the underlying technical means for their realisation currently suffer from a lack of mobility awareness as well as context awareness. This is due to the fact that existing mechanisms do not maintain the capacity to adapt to changes in the user's position and orientation. It is understood that such services can only be realised through assistance from mechanisms whereby the user's location in the physical world can be determined. However, the evaluation of this information is rarely enough for the resolution of service discovery services. That is mostly because there is no direct correspondence between the virtual and physical space. As such, when discovering local network resources the question arises as to what extent these resources are also physically local or closer than others available in other networks. This question becomes all the more important when integrated network platforms are brought into scope. In such environments connectivity can be provided over a range of access technologies. Assuming that mobile users will constantly and seamlessly vary their access network with respect to their location, cost, network or other conditions, locating services can become a challenging task. Current solutions attempt to bypass the aforementioned problem by deploying a centralised entity that is responsible for resolving the service requests for a given group of users. As such, independently of the mobile user's access network, the centralised Discovery Agent (DA) is always reachable. However, such solutions completely disregard the mobile property of future integrated network platforms and by abandoning a distributed organisation eventually restrict their own capacity. A distributed organisation approach to the problem of service location can have several advantages including localised management, faster access, faster updates and correspondence with the physical world.
For systems such as the ones presented complexity will be unacceptable. Service Discovery services will have to be navigated through a user friendly manner providing to the end-user an overview of services available in the Internet or within their physical reach. In environments with the potential for true global user centred mobility, communication services will further approach users providing solutions to problems of every day life. Specifically, new services will emerge that will enable users to locate resources and services within their physical and network environment. In accordance to the mission statement, elaborate user-centric and mobility aware services will be provided through a common service location mechanism in which a single query is translated in a range of service location requests which are in turn resolved.
Today in the field of mobility, architecture development of an integrated network platform supports bearer networks like UMTS, GPRS, GSM, IEEE 802.11b, HiperLAN2, and Bluetooth. That includes the following requirements to the network platform:
This requirements lead to transparent service discovery and provision on integrated networks, which includes the following points:
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