Abstract: A digital subscriber line framing structure supporting imbedded rate adaptive synchronous and asynchronous traffic. The frame includes a system for alternating a first payload group for the synchronous traffic with a second payload group for the asynchronous traffic in the payload portion of the frame. The size of at least one of the first and second payload groups can be modified for adapting to variations in demand for synchronous traffic over the digital subscriber line or for data rate variations over the subscriber line due to line quality variations.

Abstract: Telecommunications networks require a variety of tests to monitor their proper operations. Performance monitoring (and fault detection) of the physical layer of a transmission system is one of them and is usually accomplished by using a bit error rate test (BERT). The BERT of the invention uses modified ATM idle cells to conduct one-way, bidirectional and loopback BERT. ATM idle cells are loaded with BERT data at the transmit end and recovered at the receive end. The BERT data are processed according to the different data rates of the ATM transmission system. Performance parameters are derived from the received BERT data. The disclosure describes a method as well as a system for performing such a test.

Abstract: A set of operating parameters that define the functions of a data unit interfacing a subscriber's terminal to a 2-wire telephone loop and which are stored in a volatile memory of a microcomputer in the data unit may be changed or periodically refreshed from the same parameter set stored in a volatile memory of a microcomputer in a data line card that functions as a datapath interface of a central data and voice communication facility. Bidirectional data transmission on the loop occurs via time compression multiplexing which requires synchronization between the interfaces. Loss of synchronization indicates the likelihood of a power interruption at the data unit and consequent erasure of memory. The presence of synchronization is tested and upon a positive indication the operating parameters are downloaded from the data line card to the data unit.