Ascom Tech Ag

Thomas Kuehnel

Yung-Shain Wu

A wireless communication system for asynchronous transfer mode includes the dynamic assignment of signalling virtual channels and/or virtual paths for communications between a mobile terminal and a controller or control function. An access point associated with the wireless mobile terminal is transparent for transmitted data and control information. The dynamic assignment of the signalling virtual channel (SVC) takes place in the event of new registration to the system and handover from one access point to another. The protocol uses finite state machines and timers at the mobile terminal and at the control function. For new registrations, an assignment channel is used on a broadcast uplink from the mobile terminal to the control function to request the SVC, while the response from the control function is transmitted on the downlink broadcast channel. The response contains the unique SVCI to be used by the mobile terminal and the control function for further signalling between them. A loss of carrier connection is detected by exchanging alive messages. If there is no response to the alive messages, pending connections are released and assigned SVCs are freed. Handover from one access point to another is initiated by the mobile terminal. A new SVCI is assigned by the control function as part of the messages exchanged during the handover protocol.

Dynamic assignment of signalling virtual channels for wireless ATM

A wireless communication system for asynchronous transfer mode includes the dynamic mapping of ATM cells on a wireless ATM link into a unique Virtual Path on a wired ATM link, and in the reverse direction as well. The access point includes a radio medium access controller which assigns a unique radio connection identifier RCI to the wireless link established between the access point and a mobile terminal. The Virtual Path identifier (VPI) used on the fixed link is selected based on the RCI assigned by the access point. The radio connection identifier RCI remains unchanged as long as the mobile terminal is associated with that access point. ATM cells sent from the control function include the VPI and are mapped by the access point into the connection referenced by the RCI. ATM cells from the mobile terminal are received on a particular connection. According to the connection identifier (RCI) cells are mapped by the access point into a particular Virtual Path, which corresponds to the RCI.

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Bern, Switzerland

Thomas Kuehnel