difficult to capture by simple models. On the other hand, model based techniques have the advantage of not depending on the calibration process required to build the radio-map. This advantage favors model-based techniques in outdoor environments, where the relation between signal strength and distance can be captured by simple functions and the coverage area is large making building the radio-map a time consuming process. 3.8 MULTI-ROVER SYSTEM A single Rover system comprises of a single Rover controller, other server devices (e.g., Rover database and Rover streaming media unit), and a set of Rover clients. A single system is sufficient for management of Rover clients in a zone of single administrative control. For example, consider a Rover system in a single museum. All artifacts and objects on display in the museum are managed by a single administrative entity. There is a single content provider for this system and a single Rover system is appropriate to serve all visitors to this museum. However, each separate museum has its independent administrative authority. Therefore, we can have a separate Rover system for each of the different museums that are administered separately by each museum authority. This allows a decentralized administration of the independent Rover systems, locally by each museum authority. However, it is important to provide a seamless experience to visitors as they roam from museum to museum. A multi-Rover system is a collection of independent Rover systems that peer with each other to provide this seamless connectivity to the user population. The design of a multi-Rover system is similar in spirit to the Mobile IP [10] solution to provide network layer mobility to devices. Each client device has a Rover system to which home it is registered. As the device physically moves into the zone of a different, or Rover foreign system, it needs to authenticate itself with the Rover controller of the foreign system. Based on administrative policies, the two Rover systems have service level agreements that define the services that they will provide to clients of each other. When the Rover controller of a system detects a foreign client device, it first checks whether it has an appropriate service-level agreement with the Rover controller of the device’s
difficult to capture by simple models. On the other hand, model based techniques have the advantage of not depending on the calibration process required to build the radio-map. This advantage favors model-based techniques in outdoor environments, where the relation between signal strength and distance can be captured by simple functions and the coverage area is large making building the radio-map a time consuming process. 3.8 MULTI-ROVER SYSTEM A single Rover system comprises of a single Rover controller, other server devices (e.g., Rover database and Rover streaming media unit), and a set of Rover clients. A single system is sufficient for management of Rover clients in a zone of single administrative control. For example, consider a Rover system in a single museum. All artifacts and objects on display in the museum are managed by a single administrative entity. There is a single content provider for this system and a single Rover system is appropriate to serve all visitors to this museum. However, each separate museum has its independent administrative authority. Therefore, we can have a separate Rover system for each of the different museums that are administered separately by each museum authority. This allows a decentralized administration of the independent Rover systems, locally by each museum authority. However, it is important to provide a seamless experience to visitors as they roam from museum to museum. A multi-Rover system is a collection of independent Rover systems that peer with each other to provide this seamless connectivity to the user population. The design of a multi-Rover system is similar in spirit to the Mobile IP [10] solution to provide network layer mobility to devices. Each client device has a home Rover system to which it is registered. As the device physically moves into the zone of a different, or foreign Rover system, it needs to authenticate itself with the Rover controller of the foreign system. Based on administrative policies, the two Rover systems have service level agreements that define the services that they will provide to clients of each other. When the Rover controller of a system detects a foreign client device, it first checks whether it has an appropriate service-level agreement with the Rover controller of the device’s