Control device and control method for a digital signal in a multiple access data communications system

摘要

A variation on a carrier sense multiple access/collision detection (CSMA/CD) system protocol for local area, packet, random access, broadcast networks for effectively servicing both voice and data traffic. When the instant method is used, a mix of periodic voice traffic and aperiodic data traffic can be transmitted on a channel without the voice packets colliding. Also, an upper bound on the delay experienced by the periodic traffic can be established. In the instant method, aperiodic source contend for a channel as in conventional CSMA/CD networks. However, unlike conventional protocols, periodic sources transmit a preempt field, responsive to which aperiodic sources terminate transmission. Also unlike conventional protocols, a periodic "time slot" may be delayed up to one packet transmission time when the network is busy transmitting aperiodic data. Additional information can be transmitted in a overflow field so that a receiver can supply periodic samples at regular intervals with the advantageous result of obviating discontinuities in a reconstructed analog speech waveform. Also unlike conventional CSMA/CD networks, the system capacity can be fully utilized by periodic sources. Still further, the instant method contemplates a system with no centralized control to assign "time slots" or to reallocate capacity between periodic and aperodic sources. In addition, movable time slots allow timing discrepancies between periodic sources to be tolerated.