In a method of data transmission from a plurality of sub-stations to a main station over a common channel which is subdivided into time slots whose length and synchronization are determined by a corresponding time slot distribution of a data transmission signal sent out by the main station, in which each sub-station in each time slot has a predetermined probability p of transmitting a data packet, the throughput of the communication channel is improved in that the probability p is adapted to the load of the communication channel.

A communications controller is provided that allows transfer of a large number of frames to each of the channels of an S.sub.0 -type link to be handled simultaneously at a data transfer rate matched to that of the link. The communications controller is connected between a bus associated with at least one host computer and the terminals of a network connected by a time-multiplexed digital link. The communications controller includes a base unit connected to the bus for managing and effecting the transfer of frames for the link, and a peripheral unit connected to the base unit and to the network. The base unit has a first processor of commands for transferring frames from the host to the network and vice versa, the first processor being associated with a frame storage memory; a peripheral part comprising a coupler controlled by second processor for ensuring multiplexing or demultiplexing of the data; and a second processor, in communication with the first, for transferring frames from the frame storage memory to the peripheral part and vice versa.

An embedded system for receiving data packets from a communication network includes a plurality of buffers for storing data received from the communication network, and a pointer corresponding to each of the buffers. The embedded system also includes a device for determining whether data received from the communication network is a broadcast data, and a data controller for storing broadcast data in a predetermined number of buffers.

A retry algorithm determines the maximum number of transmissions and retransmissions that may be attempted for the frame in the head of a transmit queue or transmit buffer that needs to be transmitted across a communications link. The algorithm attempts to achieve a constant delay for each packet in frame by taking into account the number of frames residing in the transmit queue, the number of transmit opportunities elapsed between the arrivals of two successive frames in the transmit queue s, as well as the buffering capabilities of both the transmitting and receiving sides. The transmission and retransmission control technique provides for a way of managing the TX and RX buffers with a size that is suitable for the application being used and the underlying transport network. The number of retries is adapted to incoming and outgoing data rate changes in order to provide a fixed delay wireless link transport and maximize effective channel utilization.

A computer network system repetitively distributes messages including uniquely identified blocks of real time data containing a current data image over a broadcast communications network to all real time stations for storage of each repetition of each entire block of data directly in station memory at a unique address space assigned to that uniquely identified block of data. The real time stations receive the blocks of data and alternatively receive other messages from the real time stations. The other messages have a recognized standard protocol, such as the TCP/IP or UDP/IP protocol of the Internet Protocol Suite.