Got reject for frame retransmitting frame now updating nr

20-Jul-2015 07:16 by 4 Comments

Got reject for frame retransmitting frame now updating nr

2α is taken in a reciprocation, during which about 750 frames can be sent. Andrews, "Throughput efficiency of logical links over Satellite Channels," International Symposium on Satellite and Computer Communications, Apr. Meanwhile, according to the SREJ scheme, only erroneous frames are retransmitted as illustrated in FIG. At present, only the REJ scheme is used, and the SREJ scheme is merely stipulated, but is not generally used.

The retransmission method of the present invention conforms to the Go-Back-N ARQ (Automatic Repeat Request) scheme represented by the REJ scheme described before, and it executes processing with note taken of the fact that a data link for retransmission processing is constructed of a plurality of logical links.When the terminal equipment 17 has received the data normally, it sends an affirmative or acknowledgement response (ACK) back to the communication control processor 14 and delivers the received data to the corresponding application program 18, 19 or 20.When the received data involves an error, the terminal equipment 17 sends back a response in the form of a request for retransmission (REJ). 5 is a sequence chart showing the sending and receiving procedure of the present invention, while FIG.3 is a sequence chart for explaining data retransmission based on the SREJ scheme in the prior art; FIG.4 is a schematic diagram of a satellite communication network showing an embodiment of the present invention; FIG.In the HDLC protocol, the REJ (Reject) scheme and the SREJ (Selective Reject) scheme are stipulated as retransmission schemes to be used in the case where a transmission frame (a transmission data block to which a header for control is added) has undergone an error and has not properly reached the opposite side.

The REJ scheme is representative of the so-called "Go-Back-N Automatic Repeat Request scheme." As illustrated in FIG. 4 and sends back a signal REJ5 indicating a retransmission request for the frame No. 15 frames) succeeding thereto (the retransmission is indicated by double lines).Data items generated in the application programs 7, 8 and 9 are delivered to the communication control processor 14 through the channel 13.In the communication control processor 14, the data items from the logical links 10, 11 and 12 are sent to the terminal equipment 17 through the communication satellite 16 in the FIFO (first-in first-out) order and according to the high level data link control procedure (hereunder, abbreviated to "HDLC").That is, whereas the retransmission processing of the prior art has been performed in a data link unit, that of the present invention is performed in logical link unit. 4, data flows from the host computer 6 to the terminal equipment 17 and vice versa.Since, however, the flows are the same in point of processing, only the data flow from the host computer 6 to the terminal equipment 17 will be explained.7 is a schematic diagram of a satellite communication network showing another embodiment of the present invention; FIG.