Method and system for data communication

A system for transferring data supplied from a source device at a first station to a destination device at a second station via a propagation path, said propagation path including a satellite repeater and said system comprising a first station transmitter means for transmitting data over said path, at fixed intervals, said data containing a header field including an identification number identifying the data frame and an information field for accommodating user data supplied by said source device,

• said first station including transmit means for storing a list of identification numbers of previously transmitted data frames,
• said first station including buffer means connected to said transmit means for storing the contents of the information fields contained in the data frames identified by said transmit list means,
• said second station receiver means coupled to said path for receiving the transmission from said first station transmitter, said second station receiver means including means responsive to said received data for determining whether the data frames are good or bad,
• said second station including transmitter means for transmitting data frames over said path at fixed intervals, said data frames containing a header field including an identification number and an acknowledgement code indicating whether the received data frame was good or bad, and
• said first station including a processor means connected to said propagation path and receiving said data frames transmitted by said second station, said processor means responsive to said identification number of said received data frame and said respective acknowledgement code for determining whether to delete a related identification number from said transmit list or retransmit the contents of the said related information fields stored in the said buffer means.

A method of transferring large amounts of user data supplied by a source device at a first station to a destination device at a second station comprising the steps of;

• transmitting successive data frames from said first station each comprising a bit stream defining a frame sequence number and an information field accommodating a large block of data originally supplied by said source device, storing a list of frame sequence numbers identifying recently transmitted data frames and the data blocks associated with such stored framed sequence numbers,
• determining at said second station whether a data frame received thereat is good,
• transmitting successive data frames from said second station, each comprising a bit stream containing acknowledgement information including a frame sequence number identifying a data frame received from said first station and an acknowledgement code indicating whether that received data frame was good, and
• retransmitting from said first station selected ones of said stored data blocks depending upon whether the frames received at said first station indicates the data frames contained in the data blocks were good and as received at said second station.