초록 ▼

Digital data networks (such as the ISDN) which provide transmission between selected locations may use time multiplexed slots with predetermined maximum bit-rates. However local area networks (LANs) transmit packets, containing data bits, at a rate which varies frequently and often corresponds to a

Digital data networks (such as the ISDN) which provide transmission between selected locations may use time multiplexed slots with predetermined maximum bit-rates. However local area networks (LANs) transmit packets, containing data bits, at a rate which varies frequently and often corresponds to a higher bit-rate than can be handled by individual slots. In the present invention packets arriving at an input port are allocated to a number of queues each for a respective destination, and each queue is allocated a group of slots on a digital data network. The slot contents are assembled into frames in a buffer store and transmitted to the digital network. On reception, the contents of several frames of incoming multiplexed slots are held in a frame store and then assembled into packets in a number of buffers making allowance for arrival in a different slot order and different frames. Marker signals are sent periodically in each slot and these signals are used to specify the order in which the slots were transmitted and to signal when the number of slots in each group is to change to allow for variations in packet traffic.

대표청구항 ▼

A method of transmitting high bit-rate signals having a variable bit-rate including the steps of dividing a digital input signal having a bit-rate higher than a predetermined bit-rate into a sequence of subordinate digital signals having data rates equal to or less than the said predetermined bit-ra

A method of transmitting high bit-rate signals having a variable bit-rate including the steps of dividing a digital input signal having a bit-rate higher than a predetermined bit-rate into a sequence of subordinate digital signals having data rates equal to or less than the said predetermined bit-rate, transmitting the subordinate digital signals using a group of transmission channels with each subordinate signal transmitted by a respective channel, the channels in the group each being capable of handling the said predetermined bit-rate, receiving the transmitted signals, assembling the received subordinate signals to provide an output signal in which the sequence of data bits is the same as that of the input signal, changing the number of the said transmission channels making up the said group while continuing to transmit subordinate signals along those channels of the said group which are not changed, wherein a plurality of input signals are transmitted simultaneously, each input signal being transmitted by way of a respective group of the said transmission channels, each of which is duplex, and the method further including inserting marker signals from time to time in each subordinate signal in each said channel and in any other channels which are required to be added to one of the groups, the marker signals including first, second and third flag signals depending respectively on whether the channel is transmitting a subordinate signal, whether marker signals have been received in the corresponding channel, and whether a subordinate signal is no longer to be sent by this channel.