Adaptive data link protocol

A method of adaptively controlling a data link to compensate for variation in error in a transmission of data from a first terminal to a second terminal, the method comprising:

• storing data at the first terminal in a transmit memory as an array of data frames arranged in a window of the transmit memory;
• dividing the window into sub-windows each having less frames than said window;
• transmitting data from successive ones of said frames in a sequence of packets wherein data in a packet is obtained from one frame;
• embedding control signals in each of said packets, said control signals identifying packets by sequence number;
• receiving said packets at said terminals;
• checking said packets by tests for sequence number and bit error for detection of a transmission fault;
• storing data of only those packets which pass said tests in a receive memory at said second terminal, packets which fail at least one of said tests being rejected packets;
• retransmitting rejected packets from said first terminal to said second terminal;
• counting the number of rejected packets occurring during a transmission of a window of data to obtain a packet error rate;
• altering the sizes of said sub-windows in accordance with the packet error rate to maximize a speed of data transmission along said data link;
• reporting back to said first terminal from said second terminal an error signal designating the sequence number of a rejected packet;
• wherein, during said step of retransmitting, there is a retransmission of packets which were transmitted subsequent to said rejected packets in accordance with a GO-BACK algorithm;
• during said step of retransmitting, there is a step of embedding in each packet of said rejected and said subsequent packets a control signal identifying each packet as a retransmitted packet;
• the sequence number is equal to the number of the frame in said window containing data of the packet bearing said sequence number;
• and data of said receive memory is stored in an array of frames in a window of said received memory identical to the array of frames in the window of said transmit memory.

A method of adaptively controlling a data link to compensate for variation in error in a transmission of data from a first terminal to a second terminal, the method comprising:

• storing data at the first terminal in a transmit memory as an array of data frames arranged in a window of the transmit memory;
• dividing the window into sub-windows each having less frames than said windows;
• transmitting data from successive ones of said frames in a sequence of packets wherein data in a packet is obtained from one frame;
• embedding control signals in each of said packets, said control signals identifying packets by sequence number;
• receiving said packets at said terminals;
• checking said packets by tests for sequence number and bit error for detection of a transmission fault;
• storing data of only those packets which pass said tests in a receive memory at said second terminal, packets which fail at least one of said tests being rejected packets;
• retransmitting rejected packets from said first terminal to said second terminal;
• reporting back to said first terminal from said second terminal an error signal designating the sequence number of a rejected packet;
• counting the number of error signals occurring during the transmission of a window of data to obtain a packet error rate;
• wherein the sequence number is equal to the number of the frame in said window containing data of the packet bearing said sequence number;
• data of said receive memory is stored in an array of frames in a window of said received memory identical to the array of frames in the window of said transmit memory;
• subsequent to the completion of transmission of all frames of a sub-window, there is a step of sending from said first terminal to said second terminal a request signal for acknowledgement, said request signal being embedded as a part of said control signal in a subsequently transmitted packet;
• said method further comprising reporting back to said first terminal from said second terminal an acknowledgement signal acknowledging that packets previously received at said second terminal have passed said tests;
• and
• wherein an error signal is produced by comparing sequence numbers of stored data in said receive memory with frame numbers of frames storing data;
• said method
• further comprising a step of altering a repetition frequency of the acknowledgement - request signals in accordance with the packet error rate to maximize a speed of data transmission along said data link.

A method of adaptively controlling a data link to compensate for variation in error in a transmission of data from a first terminal to a second terminal, the method comprising:

• transmitting a sequence of data packets from said first terminal to said second terminal to be received at said second terminal;
• sending a request signal from said first terminal for acknowledgement of receipt of the data packets by said second terminal, said sending being done periodically after a predetermined number of data packets;
• reporting back to said first terminal from said second terminal, in response to said acknowledgement - request signal, a response signal acknowledging receipt of error - free packets, said response signal being an error signal in the case of receipt of a packet with error;
• retransmitting packets which were received with error in accordance with a GO-BACK algorithm;
• formulating a packet error rate by comparing the number of error signals with the number of packets transmitted;
• and
• altering a repetition frequency of said acknowledgement - request signals in accordance with said packet - error rate, an increase in error rate producing an increase in said repetition frequency so as to increase the transmission speed of a sequence of data packets.

A method of adaptively controlling a data link to compensate for variation in error in a transmission of data from a first terminal to a second terminal, the method comprising:

• storing data at the first terminal in a transmit memory as an array of data frames arranged in a window of the transmit memory;
• dividing the window into sub-windows each having less frames than said window;
• transmitting data from successive ones of said frames in a sequence of packets wherein data in a packet is obtained from one frame;
• embedding control signals in each of said packets, said control signals identifying packets by sequence number;
• receiving said packets at said terminals;
• checking said packets by testing for a transmission fault;
• storing data of only those packets which pass said testing in a receive memory at said second terminal, packets which fail said testing being rejected packets;
• retransmitting rejected packets from said first terminal to said second terminal;
• obtaining a packet error rate by monitoring rejected packets occurring during a transmission of a window of data;
• and
• altering the sizes of said sub-windows in accordance with the packet error rate to maximize a speed of data transmission along said data link.