This chapter details the potential found in combining to different technologies. The two basically different technologies, LBSs in mobile communication and the well-elaborated multicast technology are merged in the multicast via LBS solutions. As this chapter demonstrates, this emerging new area has a lot of possibilities, which have not been completely utilized.
The positioning technologies in the LBS solutions are based on the various distances of the communication mobile from the different base stations. With advances in automatic position sensing and wireless connectivity, the application range of mobile LBSs is rapidly developing, particularly in the area of geographic, tourist and local travel information systems (Ibach et al., 2005). Such systems can offer maps and other area-related information. The LBS solutions give the capability to deliver location-aware content to subscribers on the basis of the positioning capability of the wireless infrastructure. The LBS solutions can push location-dependent data to mobile users according to their interest or the user can pull the required information by sending a request to a server that provides location-dependent information.
LBSs process information with respect to the location of one or several persons, also referred to as targets before presenting it to the user. In recent years, LBSs have become increasingly important and have helped accelerate the development towards ubiquitous computing environments. Traditional LBSs map targets to locations (e.g., Where is person X located?), i.e., they find the position of a specific person or group of people. This type of LBS is denoted as Tracking Services.
Key Terms in this Chapter
Application-Level Network: (ALN): The applications, which are running in the hosts, can create a virtual network from their logical connections. This is also called overlay network. The operations of such software entities are not able to understand without knowing their logical relations. In most cases these ALN software entities use the P2P model (see below), not the client/server (see below) for the communication.
Multicast Routing Protocol: In order to forward the multicast packets, the routers have to create multicast routing tables using multicast routing protocols.
IP-Multicast: Network-level multicast technology, which uses the special class-D IP-address range. It requires multicast routing protocols in the network routers. Its other name: Network-Level Multicast (NLM).
Ad-hoc Computer Network: Mobile devices that require base stations can create the ad-hoc computer network if they do not need routing infrastructure.
Autonomous System: (AS): A network with common administration; it is a basic building element of the Internet. Each AS is independent from the others.
Peer-to-Peer (P2P): It is a communication model where each node has the same authority and communication capability. They create a virtual network, overlaid on the Internet. Its members organize themselves into a topology for data transmission.
Multicast Tree: A virtual graph, which gives the paths of sending multicast data from the source (the root of the tree) to the nodes of the tree. Its other name: Dissemination tree or Distribution Tree.
Application-Layer Multicast: (ALM): A novel multicast technology, which does not require any additional protocol in the network routers, since it uses the traditional unicast (one-to-one) IP transmission. Its other name: Application-Level Multicast (ALM).
Client/Server Model: It is a communicating model, where one hardware or software entity (server) has more functionalities than the other entity (the client), whereas the client is responsible to initiate and close the communication session towards the server. Usually the server provides services that the client can request from the server. Its alternative is the P2P model (see below).
Geocast: One-to-many communications among communicating entities, where an entity in the root of the multicast distribution tree sends data to that certain subset of the entities in the multicast dissemination tree, which are in a specific geographical area.