Adaptive data link protocol

Claim 1

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; counting the number of rejected packets occurring during a transmission of a window of data to obtain a packet error rate; and altering the sizes of said sub-windows in accordance with the packet error rate to minimize the delay of re-transmission and increase the utilization of the link.

Claim 2

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; counting the number of rejected packets occurring during a transmission of a window of data to obtain a packet error rate; and altering the sizes of said sub-windows in accordance with the packet error rate to minimize the delay of re-transmission and increase the utilization of the link.

Claim 13

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; 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 transmitting, there is a retransmission of packets which were trans­mitted subsequent to said rejected packet in accordance with a GO-BACK algorithm; during said step of retransmitting, there is a step of embedding in each packet 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.

Claim 14

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; 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 transmitting, there is a retransmission of packets which were trans­mitted subsequent to said rejected packet in accordance with a GO-BACK algorithm; during said step of retransmitting, there is a step of embedding in each packet 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.

Claim 16

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.

Claim 17

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.

Claim 18

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.

Claim 19

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.