Data retransmitting method in communication network

Claim 2

A data retransmitting method in a communication network wherein a plurality of sending and receiving stations are connected through communication channels (15, (42, 44, 46, 4 8), a computer (5) or terminal equipment (17) is coupled to each of the sending and receiving stations by a data link, and the data link is shared by a plurality of logical links (10, 11, 12, 13) comprising: the step of transmitting transmission frames in logical link unit by means of the station on a sending side; the step of sending back, upon detecting that any of the transmission frames has not been received properly, a request for retransmission of the particular frame by means of the station on a receiving side, the subsequently received frames of the logical links other than the logical link of said particular frame being delivered to the corresponding logical links; and the step of transmitting, upon receiving the retransmission request from the receiving side station, only the frames belonging to the same logical link as that of said particular frame among the frames transmitted since said particular frame, by means of the sending side station.

Claim 3

A data retransmitting method according to claim 1, wherein each of said sending and receiving stations has a second retransmission mode of transmitting and receiving only the erroneous transmission frame again, in addition to the above-stated first retransmission mode of transmitting and receiving the erroneous transmission frame and the subsequent series of already transmitted frames again, and it selects either of the first and second retransmission modes in accordance with a current condition of the communication channel and then performs the operation of retransmitting the erroneous frame.

Claim 4

A data retransmitting method according to claim 2, wherein each of said sending and receiving stations performs: the step of deciding whether or not change of the retransmission modes is necessary, according to the current condition of the channel; the step of transmitting, when the retransmission mode change has been decided necessary, a frame to that effect to the opposite station; the step of transmitting, when the frame requesting the retransmission mode change has been received, a frame responsive thereto; and the step of changing the current retransmission mode to the other retransmission mode after the retransmission mode change requesting frame or the responsive frame has been received.

Claim 5

A data retransmitting method in a communication network wherein a plurality of sending and receiving stations are connected through satellite communication channels and wherein a computer (6) or terminal equipment (17)is coupled to each of the sending and receiving stations by a data link, each of said sending and receiving stations performing: the step of starting data transmission and reception after selecting either of a first retransmission mode of transmitting and receiving an erroneous transmission frame and a subsequent series of already transmitted frames again and a second retransmission mode of transmitting and receiving only the erroneous transmission frame again; the step of monitoring a channel quality and transmitting a first frame, which requests change of the retransmission modes, to the opposite station in accordance with a result of a comparison of the monitored quality with a predetermined reference; the step of transmitting a second frame, which acknowledges the mode change, in response to the retransmission mode change requesting frame from the opposite station; and the step of changing the current retransmission mode to the other retransmission mode and then executing data transmission and reception after receiving the first or second frame.

Claim 6

A data retransmitting method in a communication network wherein a plurality of sending and receiving stations are connected through satellite communication channels and wherein a computer (6) or terminal equipment (17)is coupled to each of the sending and receiving stations by a data link, each of said sending and receiving stations performing: the step of starting data transmission and reception after selecting either of a first retransmission mode of transmitting and receiving an erroneous transmission frame and a subsequent series of already transmitted frames again and a second retransmission mode of transmitting and receiving only the erroneous transmission frame again; the step of monitoring a channel quality and transmitting a first frame, which requests change of the retransmission modes, to the opposite station in accordance with a result of a comparison of the monitored quality with a predetermined reference; the step of transmitting a second frame, which acknowledges the mode change, in response to the retransmission mode change requesting frame from the opposite station; and the step of changing the current retransmission mode to the other retransmission mode and then executing data transmission and reception after receiving the first or second frame.

Claim 7

A data retransmitting method according to claim 4, wherein each of said sending and receiving stations uses said data link in common for a plurality of logical links, and the station on a sending side transmits the transmission frames in logical link unit and retransmits only the frames belonging to the same logical link as that of the frame for which the retransmission has been requested, among the frames transmitted since the requested frame during the data transmission in the first retransmission mode.