Abstract: A line interface controlling unit terminates a synchronous digital interface. A bandwidth controlling unit generates a timing signal for specifying respective timings of a plurality of time slot groups (TS groups) in order to divide a plurality of time slots structuring the interface into the plurality of time slot groups. Division specification of the TS groups is made from a controlling device. A plurality of cell mapping controlling units identify each of the TS groups in the interface based on the timing signal, and map data streams of asynchronous fixed-length cells, which respectively belong to a plurality of communication device interfaces, onto each of the identified TS groups, for example, via a communication device interface controlling unit.

Abstract: A method of an automatic adjustment of a carrier level is used for a system having a center device, a communication line extending from the center device, and at least one communication-terminal device connected to the communication line. The system conducts two-way communication of data signals on the communication line based on a predetermined multiplexing scheme.