Abstract: A technique that can effectively utilize unused wireless link and realize high-quality wireless communication between a communication terminal and a base station and enables efficient distribution of radio resources over an entire wireless communication system is provided. A wireless communication system in which a base station and a communication terminal can conduct wireless communication by detecting a usable wireless link and changing a wireless link used for the connection is also provided. On the communication network side, in addition to a plurality of wireless communication networks and a base station, a server device is provided.

Abstract: A method in which communication quality of a base station is accumulated according to type of an application and when a communication terminal device switches a base station, an optimal base station for each application is selected is provided. A wireless communication device of the present invention is provided with priority notifying means storing priority information of communication conducted by the local device and notifying it to the other wireless communication devices so that the priority can be notified to the outside. A priority information collecting means collects the priority information notified by the other devices, and a priority information comparing means compares the priority information of the local device with the collected priority information. Wireless communication control means is provided so that as the result of comparison, if the priority of the other devices is higher than the priority of the local device, the wireless communication means is controlled.

Abstract: To provide a method of selecting an optimal base station for each application when accumulating communication quality in response to an application type for a base station and a communication terminal switches base stations. A communication quality database 31 is prepared by assigning a current location of a communication terminal device, a currently running application program and a communication quality when executing an application program. When making a new connection with a base station, the current application and location is used to select a base station having an optimal communication quality from the communication quality database 31. This mechanism may be provided in the communication terminal device or may be provided as a communication system including a server device.

Abstract: To provide a technology with which a large number of wireless communication networks can be efficiently used while the size of a device operated by a user is reduced and power is saved by providing a communication terminal whose connection with a different wireless communication network can be dynamically reconfigured. A communication terminal 20 whose connection method or the like with a plurality of wireless communication networks can be dynamically reconfigured is provided with a data communication aggregation device 21, a communication application executing device 22, and a local communication path 23 for connecting the data communication aggregation device and the communication application executing device.

Abstract: The present invention provides a technology of effectively avoiding tracing on a terminal performed with an identification number being a target and DoS attack without making any significant changes to a communication system. In the wireless communication system of the present invention, under a control of a control communication processing portion 113 of an access point, a hash function arithmetic operation processing portion 112 generates a third identification number to be updated using a current identification number, hash key and random number for any wireless communication terminal, a control communication processing portion 113 sends an update instruction signal containing the random number to the wireless communication terminal and updates the current identification number stored in the identification number storage portion 121 to a second identification number.