JPS6196844A - Receiver for multiple address communication - Google Patents

Abstract

PURPOSE:To attain retransmission to plural erroneous reception frames at the same time at the retransmission of one frame to plural erroneous reception frame by providing a reception discriminating circuit receiving an information frame and discriminating whether the frame is a frame to be received or not and an FIFO buffer retarding the received information frame to a prescribed number. CONSTITUTION:When a received frame is a retransmission frame, a reception discriminating circuit 3 inputs an information part of the said retransmission frame to an exclusive OR circuit 6 via a latch switch 5. On the other hand, the information part of the retransmission frame is latched by the latch 5, and while one input of the exclusive OR circuit 6 is kept open (that is, zeroed), the exclusively OR circuit 6 has an input, then the information part of the retransmission frame is stored as it is in a buffer 7 via a switch 8. Each reception station applies exclusive OR to the said retransmission frame and the information stored in the buffer 7 to restore a desired erroneous frame.

Description

[Detailed Description of the Invention] Industrial Application Fields With the diversification of communication forms such as various information provision services and conference communications, the decentralization of databases in communication networks, and the use of satellite lines, it is becoming increasingly difficult to simultaneously share information with the same content. The importance of "broadcast communications" that are forwarded to multiple destinations is increasing. The present invention relates to a receiving device in a receiving station when performing the above-mentioned broadcast type communication.

(Prior art and its problems) Communication in which there are multiple communication partners and the same information is transferred to multiple destinations at the same time is called broadcast communication. Automatic error retransmission control (ARQ: AUTO) in broadcast communication
MATICR, FiPEAT RBQUEST) various protocols have been proposed, and one of them is a method called SELECTIVE REPEAT. In this method, the transmitting station transmits a plurality of information frames and only retransmits the information frame for which a retransmission request was made due to an error message received from the valley receiving station. However, unlike the case of one-to-one communication, since there are a plurality of receiving stations, the frames that are received in error are generally different for each receiving station. For example, 1oaI sent by the transmitting station! Of the information frames of i1, receiving station 1 receives the 2nd frame, receiving station 2 receives the 7th frame, and receiving station 3 receives the 9th frame. In response to a retransmission request from the station, the second frame, seventh frame, and ninth frame must be retransmitted. However, in this case, for example, receiving station 1 is the only one that received the second frame, and the other receiving stations have received the second frame incorrectly. In this way, even though each receiving station "i significantly deteriorated compared to the previous case.

(Objective of the present invention) An object of the present invention is to, when a plurality of receiving stations receive different information frames in error in broadcast communication, instead of retransmitting all the erroneously received frames one by one,
It is an object of the present invention to provide a receiving device for use in a retransmission system that enables simultaneous retransmission of a plurality of erroneously received frames by retransmitting one frame for a plurality of erroneously received frames.

(Structure of the Invention) According to the present invention, there is provided a receiving device that enables each receiving station in a broadcast type 7F1 signal to effectively perform retransmission when it receives an information frame, and receives an information frame. A reception determination circuit that determines whether the frame should be received, and an F for sending a predetermined number of received information frames.
'IFO buffer, an exclusive OR circuit and buffer for sequentially exclusive ORing and counting the information frames received before the predetermined number of bits, and a buffer for storing normally received information frames. A receiving device is provided, characterized in that it is equipped with a buffer for transmitting a receiving response, and a receiving response transmitting device for transmitting a receiving response.

(Principle of the Invention) The present invention achieves the above object based on the principle described below.

N equal length M) bit strings (x(1,1).

x (2, 1), -, x (M, 1)), (x (1, 2
), x(2,2),.

x(M, 2)L”'+ b(1,N), x(2,N
)+-x(M, N)), y(j)"x(L 1)■x(3,2)-・@x(j
, n) (j=1.2.-...() Here, ■ indicates exclusive OR.

The length M(?) formed by y(j) obtained by the operation is
) bit string (, +1), yf2+, ...y(M)
) is called an N-sum bit string. By defining each bit string as above, when we know an arbitrary N-11 bit string among the original N if5 bit strings, we can combine these N-1 bit strings and n=N sum bit string bit by bit. The remaining one bit string can be obtained by performing an exclusive OR on . Based on this principle, the transmitting station retransmits a frame obtained by exclusive ORing of several frames bit by bit instead of retransmitting the 5F- frame. At that time, the frame to be exclusive-ORed is determined according to the method described later, so that each receiving station receives at most one error among the multiple exclusive-ORed frames that make up the retransmitted frame. Therefore, no matter what frame the receiving station received in error, it is possible to recover the erroneous frame by retransmitting the one exclusive OR frame.

The transmitting station continuously transmits information frame 1, and when it receives the first retransmission request for a frame that is not included in the range of the previous retransmission, it records the name of the receiving station and the number of the four received frames, For subsequent retransmission requests,
The received i's'J name is recorded. If 2 from the same station
When the second retransmission request comes, the bit-by-bit exclusive logic of all frames transmitted before the second error-received frame (not including the second error-received frame) Resend the summed frame. If a predetermined number of frames have been transmitted before the second retransmission request comes from the same station, counting from the first erroneously received frame that is not included in the range of the previous retransmission, the reception Bureau
In order to prevent buffer overflow in step 1, the frame values that have received an acknowledgment (-) by that point are exclusive summed and retransmitted. In either case,
Each receiving station is within range of the retransmitted frames; in this case, there is at most one frame received in error.

If a retransmission frame is received in error, there is a risk that the receiving station's buffer will overflow, so the same retransmission frame may be sent out in duplicate depending on the error rate of the transmission path.

(Example) The present invention will be described in detail below using the drawings. For the sake of explanation hereinafter, the round-trip propagation delay of the transmission path will be referred to as S frame. (In other words, after transmitting a certain frame, eight frames are transmitted before receiving a reception response for that frame.) FIG. 1 is a block diagram showing one implementation flJ of the present invention. The received information frame is input from an input terminal 1 and is input to a reception determination circuit 3 via a receiver 2. If the reception determination circuit 3 receives a frame other than the frame for which reception is being repeated, the reception determination circuit 3 ignores the received frame. When the received information frame is received normally, the information portion of the received frame is input to the F'IFO buffer 4, and a signal indicating normal reception and the frame number are sent to the reception response transmitter 11.

The reception response transmitting device 11 transmits a reception response indicating normal reception from the terminal 13 via the transmitter 12. If the received information frame is received in error, the reception determination circuit 3 inputs zeros corresponding to the information frame into the FIFO buffer 4, and notifies the reception response transmitter 11 of the frame number along with a signal indicating the error reception.

The reception response transmitter 11 transmits a retransmission request from the terminal 13 via the transmitter 12. The FIFO buffer 4 has a capacity (s
+i) Every time one frame is input, the S+1th frame from the right end is outputted and inputted to the buffer 9 and also inputted to the exclusive OR circuit 6 via the latch switch 5.

The output from the buffer 7 is input to the other input terminal of the exclusive OR circuit 6, and the bit-by-bit exclusive ORed output is stored in the buffer 7 again via the switch 8. Buffer 7 has a capacity for one frame. If the received frame is a retransmission frame, the reception determination circuit 3 inputs the information portion of the retransmission frame to the exclusive OR circuit 6 via the latch switch 5. The output from the buffer 7 is input to the other input of the exclusive OR circuit 6, and the output obtained by exclusive ORing the bits at is sent to the buffer 9 via the switch 8, and is stored in the position of the frame that was received in error. is written into. Normally received information frames are sequentially output from the buffer 9 to the output terminal 10. On the other hand, the information part of the above retransmitted frame is latched in the latch 5, and by inputting it to the exclusive OR circuit 6 again while the other input of the exclusive OR circuit 6 is cut off (that is, kept at zero). , the information portion of the retransmitted frame is directly stored in the buffer 7 via the switch 8. In this way, the buffer 7 of each receiving station always stores the bit-by-bit exclusive OR of frames in the same range as the incoming retransmitted frame. Since retransmitted frames are sent at such intervals that there is at most one frame, each receiving station can eliminate the desired error by exclusive ORing the retransmitted frame and the one stored in the buffer 7 yen. frames can be recovered.

FIG. 2 is a block diagram showing an example of the configuration of a transmitting device that generates a signal to be supplied to the present invention. The information frame to be transmitted is input to the F'IFO buffer 1G from the terminal 14 via the latch 15, and is also input to the F'IFO buffer 1G via the switch 20. The signal is sent out from the terminal 23 to the transmission path via the transmission information addition circuit 21 and the transmitter 22. The contents of the FIFO buffer 16 are shifted to the right by one frame every time one frame is input from the left side. FIFO buffer 16 capacity? is (S+
1) For a frame. F'I F O buffer 16
The output from the XOR circuit 17 is input to one input terminal of the exclusive OR circuit 17. The output of the retransmission buffer 18 is input to the other input terminal of the exclusive OR circuit 17.
The output of the sum circuit 17 is stored again in the retransmission buffer 18. The retransmission buffer 18 has a capacity for one frame, and its output is exclusively input to the input of the fate summation circuit 17, and is also input to one input terminal of the buffer 19 and the switch 20. On the other hand, a reception response from each receiving station is input from a terminal 26 to a reception determination circuit 24 via a receiver 25. If the received reception response is the first retransmission request for a frame that is not included in the range of the previous retransmission frame, the reception determination circuit 24 records the frame number and receiving station. From then on, each time a retransmission request comes, record the receiving station name, and if a second retransmission request comes from the same station, or receive S-1 reception responses counting from the first retransmission request frame recorded above. If received, the latch 15 is turned off, the switch 20 is switched to the output from the retransmission buffer 18, and the inner ear of the buffer 18 is switched to the output from the retransmission buffer 18.
, the information addition circuit 21, and the transmitter 22. At that time, the buffer 18 contains a one-bit exclusive OR of frames up to a frame number one smaller than the frame number of the reception response received immediately before.

(Advantages of the Invention) As explained above, according to the present invention, the number of retransmissions is smaller than that of the conventional automatic retransmission control method. The effects of the present invention are most noticeable when each receiving station receives different frames one by one in error. For example, if M receiving stations all receive different frames one by one in error, the conventional method requires retransmission of M frames, but the present method requires only one retransmission.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. ii2 is a block diagram showing an example of a transmitting device for transmitting information frames received by the viewing device. In the figure, 1.14.26 is an input terminal, 2.25 is a receiver, 3 is a reception judgment circuit, 4.16 is a FIFO buffer,
5 is a latch switch, 6.17 is an exclusive OR circuit, 7
．． 9.19 is a buffer, 8.20 is a switch, 10.1
3.23 is an output terminal, 11 is a reception response transmitter, 12.
22 is a transmission value, 15 is a latch, 18 is a retransmission buffer, 21 is a transmission information addition circuit, and 24 is a reception determination circuit. Uchihara Shingo Kazuo Lie

Claims (1)

[Claims] A reception device for broadcast communication that performs broadcast communication in which information with the same content is simultaneously transferred to multiple destinations, a reception determination circuit that receives an information frame and determines whether the frame is a frame that should be received; A FIFO buffer for sending a predetermined number of received information frames, and an exclusive OR circuit and buffer for sequentially exclusive ORing and storing information frames received before the predetermined number of frames bit by bit. 1. A receiving device comprising: a buffer for storing normally received information frames; and a receiving response transmitting device for transmitting a receiving response.