Primary rate access (PMXA) in subscriber loops

The preliminary rate access (PMXA) connects ISDN (integrated-services digital network) user equipment with 2 Mb/s interfaces to the digital local exchange. At present, two types of network access are provided: the basic access with two user (B) channels and one signalling channel (D) for main stations and small PBXs, and the primary rate access with several basic accesses for medium to large digital PBXs. The primary rate access has 30 B-channels plus one 64 kb/s signalling channel (30*B+D64). The PMXA signal, with a gross bit rate of 2048 kb/s, is mainly transmitted over existing balanced-pair voice-frequency copper cable. For new subscriber loops, fiber-optic cable is being installed. An in-depth analysis of the line equipment for the PMXA is provided. The network termination and the line termination for transmission via copper cable and optical fiber are described.<
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