| 摘要 |
An ATM cell constructor of an ATM transmitter assembles a stream of frames of constant bit-rate traffic received on a listen TDM bus into cell payloads using ATM adaptation layer 1 (AAL1 ). Once every eight cells, the AAL1 structured data transfer (SDT) cell constructor layer introduces a one-octet SDT offset pointer into the payload. This pointer designates traffic-block (TDM frame) boundaries. The payload with an attached ATM header forms an ATM cell, and the constructor transmits a stream of the ATM cells, carrying traffic of one wideband channel, to a receiver. A receiver receives one or more streams of the ATM cells from one or more transmitters. During each frame interval, an ATM cell deconstructor of the ATM receiver disassembles a block's worth of traffic from a received ATM cell of each received stream, assembles the disassembled traffic from every stream into a TDM frame, and transmits the frame on a talk TDM bus. In response to commencing to disassemble a whole block's worth of traffic from an ATM cell that includes the SDT offset pointer, the deconstructor adjusts the disassembling to commence the disassembling of the whole block's worth of traffic at the block boundary pointed to by the SDT offset pointer, thereby aligning frames on the talk TDM bus with the frames on the listen TDMbus. The listen and talk TDM buses are thereby synchronized with each other.
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