DIGITAL HIERARCHY BASED COMMUNICATION SYSTEMS

摘要

An interface device for providing a gateway function between lines of a public switched telephone network (PSTN) that carry digital hierarchy signals and an asynchronous transfer mode (ATM) backbone network that carries signals in ATM format, the interface device comprising: a telephony transceiver operative to receive upstream hierarchy signals in a plurality of hierarchies; a hierarchyconverter operative to convert at least some of the upstream hierarchy signals to upstream signals in a single digital hierarchy distributed over a plurality of logical channels; an inverse multiplexing unit operative to inverse-multiplex the upstream signals in the single digital hierarchy; an ATM framer operative to map at least some of the upstream inverse-multiplexed digital hierarchy signals into ATM cells; and an ATM transceiver operative to transmit the upstream signals in ATM format to the ATM backbone network.