| 摘要 |
<p>The system allows packet synchronous speech communications in the network without requiring any centralized device synchronizing all the network stations. To obtain that, the active periods of each station are subdivided asynchronous, packet switched data traffic accesses the transmission line by means of a distributed contention algorithm, such as CSMA-CD. The access to the line for a speech communication is obtained by the same contention technique as used for data transmissions but, once a station has accessed the line for a speech communication, this communication is allotted a synchronous channel which is maintained for the whole communication duration. To obtain that, each station organizes its activity into frames, having a duration equal to the speech packetization time, and builds up independently, on a frame by frame basis, the busy period timing map, by monitoring the transmission line activity and recording the beginning instants of speech packets. Provided that at the occurrence of a particular busy period only the station that has booked it can transmit, each busy period in the map sets up a synchronous channel for a speech communication.</p> |
