KR20020032730A - Data repeat apparatus and method thereof - Google Patents

Abstract

PURPOSE: An automatic data repeat apparatus and a method thereof are provided to improve transmission efficiency and delay time of a frame by judging and automatic-repeating a data frame which requires an automatic repeat without receiving a negative acknowledgement. CONSTITUTION: A transmission buffer(10a) sequentially stores a data frame from an upper layer according to the serial number of the data frame. A negative acknowledgement frame receiver(10b) receives a negative acknowledgement frame. A receiving buffer status receiver(10d) receives a status of a receiving side. A delay timer(10e) transmits data and drives a constant time. A data transmission controller(10c) performs an automatic repeat of a frame required when receiving the negative acknowledgement and an automatic repeat of a frame included in the transmission buffer(10a). The data transmission controller(10c) controls the transmission buffer(10a) according to values of the receiving buffer status receiver(10d) and the delay timer(10e).

Description

Data retransmission apparatus and method thereof

The present invention relates to a method and apparatus for retransmission of a data frame, and in particular, a transmitting end (NAK) for a transmitter to improve performance of a radio link protocol using a selective repeat automatic repeat request. The present invention relates to a data retransmission apparatus and method for improving transmission efficiency and delay time of a frame by determining and retransmitting a data frame requiring retransmission without receiving a negative acknowledgment.

More specifically, the present invention, by adding a device capable of receiving any variable value indicating the state of the receiving buffer to the transmitting end, and after the transmitting end transmits the data frame to drive the one week delay timer, after the completion of the timer The frame is retransmitted according to any variable value received.

In general, in transmitting and receiving data, an automatic repeat request (ARQ) method is used to recover data frames lost during transmission.

There are various methods of automatic retransmission, and the STOP-AND-WAIT method transmits the next frame only after receiving a positive acknowledgment that the data frames have been successfully transmitted one by one.

Also, the GO-BACK-N method retransmits all frames after a frame that failed to transmit after sending several frames.

In addition, the selective repeat automatic repeat request method is a method of requesting retransmission only for data frames that have not been successfully transmitted to the receiving end.

Among the methods for data retransmission, the selective repeat retransmission request is also used in the Radio Link Protocol (RLP) of the IS-95 or CDMA2000 system supporting the wireless data transmission service, and is standardized through the IS-707 document. .

1 is a block diagram of a transmitter and a receiver of a conventional selective retransmission method of a method for data retransmission.

The transmitting end 10 has a transmission buffer 10a for sequentially storing data frames descended from the upper layer according to the serial number of the data frame, and a negative response frame receiver 10b for receiving a negative response frame when a negative response frame occurs. And a frame transmission controller 10c which is responsible for retransmission of the requested frame and retransmission of the frame in the transmission buffer when the negative response frame is received.

The receiving end 20 stores data at a corresponding position according to the serial number of the data frame received from the transmission buffer 10a and retransmits it through the negative response frame generator 20b when the received data frame is lost. It consists of a receiving buffer 20a for transmitting the serial number of the required frame.

2 illustrates a communication procedure illustrating a conventional selective retransmission method, in which a negative response is generated when data frames # 2 and # 3 are not received and retransmits # 2 and # 3.

3 shows the internal structure of the transmission buffer 10a of the IS-707 standard, and uses the variable L_V (S) indicating the state of the buffer. L_V (S) represents the serial number of the next frame to be transmitted, and the variable value in FIG. 3 is L_V (S) = 5.

4 shows the internal structure of the receiving buffer 20a of the IS-707 standard, and uses variables L_V (R) and L_V (N) indicating the state of the buffer. L_V (N) represents the serial number of the oldest frame among the data frames that need retransmission, L_V (R) represents the serial number of the new data frame to be received next, and each variable value in FIG. 4 is L_V. (N) = 4 and L_V (R) = 9.

The above L_V (Long Variable) is a variable indicating the current state of the buffer, L_V (S), (R), N), etc. may be referred to as a single data bundle.

Hereinafter, a conventional selective repeat transmission method will be described with reference to the drawings.

The transmitting and receiving end structure for the selective repeat transmission request method is shown in FIG. When data is input from the upper layer, these frames are stored in order in the transmission buffer 10a. The frame transmission controller 10c of the transmitting end 10 is responsible for the transmission of the data frame in the transmission buffer, and in turn determines whether to transmit the data frame in the transmission buffer or retransmit the lost frame during transmission. The frame information that needs to be retransmitted is included in the negative response frame received from the receiving end 20, and the frames in the transmission buffer are sequentially transmitted while the negative response frame is not received.

The receiving end 20 receives the data frames in the order sent by the transmitting end 10 and stores them in the receiving buffer 20a. However, since the transmission of a data frame may fail during transmission, a frame that has not been successfully transmitted needs to be retransmitted. Therefore, a frame that is lost during transmission and needs to be retransmitted transmits a serial number of the frame to the transmitter through the negative response generator 20b, and the transmission controller 10c receiving the negative response frame retransmits the corresponding frame.

Generally, an acknowledgment is used together with a negative acknowledgment for retransmission of a frame. However, all the retransmission request methods used in the IS-707 are made with only negative acknowledgments. That is, retransmission is requested only for frames that are not received at the receiving end. At this time, it is determined that the transmission of a specific frame fails because the data frames are received out of order.

2 is an embodiment for retransmitting a conventional data, but the transmitting end sequentially transmits from the frame having the serial number 0, but when the frame having the serial numbers 2 and 3 is lost during transmission due to the poor channel environment, the receiving end performs the serial transmission. Receive the frame number 4 after the frame number 1. Since the transmitting end must transmit frames in order, the receiving end immediately determines that frames 2 and 3 are lost. Thereafter, the receiving end transmits a negative response signal to retransmit frames 2 and 3, and the transmitting end immediately retransmits them.

To this end, the transmitting end needs to store the data in the transmission buffer for a certain period of time without discarding the frame already transmitted for retransmission of the data frame, and the receiving end also stores the data in the receiving buffer for a certain period in order to store and recombine the retransmitted frame. Must be saved. Therefore, the transmit buffer and the receive buffer must be large enough to satisfy this.

3 shows the internal structure of the transmission buffer and uses L_V (S) which is a variable for indicating the state of the buffer. L_V (S) indicates the serial number of the frame to be transmitted next to the last transmitted frame, and increments by one each time data frames are transmitted one by one. The variable value in FIG. 3 is L_V (S) = 5.

4 shows the internal structure of the reception buffer, and variables L_V (R) and L_V (N) are used to indicate the state of the buffer. As shown in the figure, L_V (N) represents the serial number of the oldest frame among the data frames that need to be retransmitted, L_V (R) represents the serial number of the new data frame to be received next, and each variable in FIG. The value is L_V (N) = 4, L_V (R) = 9, and the Negative Response Frame Generator transmits Negative Response frames only for the frames that failed to transmit among the frames between L_V (N) and L_V (R). The frames transmitted by the Negative Response Frame Generator at 4 are 4 and 6.

The receiver creates and manages a NAK List for the frames requiring retransmission. After retransmission is requested, the negative response retransmission timer is started for each frame, and the serial number of the frame is registered in the negative response list. If the frame is not received until the active Negative Response Retransmission Timer expires, the frame is requested to be retransmitted again. If the frame is successfully received, the timer is stopped and the serial number of the frame is deleted from the list. In IS-707, if the negative resend timer expires after the negative response is sent, the negative response is sent twice and the negative resend timer is restarted. Once the frame does not arrive until the Negative Resend Timer expires, the NACK Abort Timer is sent three consecutive times. The Negative Stop Timer is used by the IS-707 to avoid infinite retransmission of infinite Negative Responses.If the requested frame does not arrive until the Negative Abort Timer expires, it stops sending any further Negative Responses to the higher layer. Be notified. In the negative response list managed by the receiving end, the serial number of the frame for which retransmission is requested, the state of the negative response retransmission timer and the negative response stop timer are recorded, and when the requested frame is received, it is deleted from the list.

However, the conventional data frame retransmission method is performed solely by transmitting a negative response. That is, only when the receiving end recognizes that the frame did not arrive properly, the transmitting end may request retransmission. However, in a wireless channel environment in which the state of the channel is not good, when all the transmitted frames are lost, the receiving end does not receive any frame and transmits no acknowledgment frame by determining that there is no transmitted frame. Accordingly, the transmitting end that does not receive the negative acknowledgment frame determines that the frames transmitted by the sender are successfully transmitted, and does not retransmit, even though retransmission of the lost frames is necessary. However, after the next frame is transmitted, the receiving end detects the loss of the frame, or the idle timer of the transmitting end expires, and the idle frame (transmitting confirmation or line connection is maintained during Idle Frame, transmitting end or after completion). It is possible to retransmit these frames only when the receiving end detects the loss of the frames. Therefore, even when retransmission is required, a situation may occur in which the transmitting end does not take any action for a long time.

Accordingly, in order to solve the above problem, the present invention provides a method in which a separate device and a transmitter transmit data frames so that the transmitter receives variable values such as L_V (R) and L_V (N) indicating the state of the reception buffer. Apparatus and method for retransmitting a frame according to L_V (R) and L_V (N) values received after expiration of the one-week delay timer by adding a round-trip delay timer that can be arbitrarily driven afterwards Suggest.

At this time, the L_V (R) and L_V (N) information needs to be modified to be included in a NAK control frame, a fill frame, and a data frame transmitted from a receiver. After transmitting the frame, the transmitting end may arbitrarily drive the one-time delay timer, and the L_V (S) value is recorded in the list. The expiry time of the circumferential delay timer may be set to a maximum time or a minimum time until the frame sent from the transmitting end arrives at the receiving end and returns to the form of a negative response frame.

If the L_V (R) value received after the expiration of the one-week delay timer is smaller than the L_V (S) value, frames with a serial number equal to or greater than L_V (R) are transmitted again.

1 is a block diagram of a transmitting and receiving end of a conventional selective retransmission method;

2 is a communication procedure showing a conventional selective retransmission method

3 shows the internal structure of the transmission buffer of the IS-707 standard.

4 shows the internal structure of the receiving buffer of the IS-707 standard.

5 is a block diagram of a transmitting and receiving end of a selective repetitive retransmission method according to the present invention.

6 is an operation example of the present invention.

7 is an embodiment flow diagram for retransmission of a data frame of the present invention.

A system for transmitting data of the present invention comprises: a transmission buffer for storing input data for transmission; A reception buffer for receiving data of the transmission buffer; A negative response data generator for outputting data not received by the received data, and a reception buffer state transmitter for outputting a state of a reception buffer; A negative response data receiver for receiving a negative response output from the receiving side, a receiving buffer state receiver for receiving a state of the receiving side; A week delay timer for driving for a predetermined time after transmitting data; And a data transmission controller for controlling the transmission buffer according to the value of the negative response data receiver, the reception buffer status receiver, and the circumferential delay timer.

In addition, the system for transmitting data of the present invention comprises the steps of: driving a timer for time constant; Recording a recognition value of a data bundle transmitted when the timer is driven; Receiving an acknowledgment value of the data bundle received from the receiving buffer returned by the receiving end; and recognizing a value of the data bundle transmitted when the timer is driven when the timer recognizes the received data bundle when the timer expires. And comparing and retransmitting data according to the comparison result.

In addition, the system for transmitting data of the present invention comprises the steps of: driving a timer for time constant; Recording a recognition value of a data bundle transmitted when the timer is driven; Receiving a recognition value of an unreceived data bundle in a reception buffer returned by the receiving end; Comparing the recognition value of the received data bundle when the timer expires and the recognition value of the data bundle transmitted when the timer is driven; And retransmitting the data bundle according to the comparison result.

In the system for transmitting data of the present invention, the recognition value of the data bundle is a serial number indicating the transmission order.

In addition, in the system for transmitting data of the present invention, when a plurality of timers for each data bundle to be transmitted are driven, a recognition value of the received data bundle in the received reception buffer is applied to the plurality of timers whose operation has expired. If it is smaller than the recognition value of the corresponding transmitted data bundle, it is compared with the recognition value of the largest transmitted data bundle and retransmitted.

Hereinafter, an apparatus and method for retransmitting data according to the present invention will be described with reference to the accompanying drawings.

FIG. 5 is a block diagram of a transmitting and receiving end of a selective repetitive retransmission method of the present invention among data retransmission schemes, and is due to a negative acknowledgment (NAK) retransmission in the IS-707.

The transmitting end 10 has a transmission buffer 10a for sequentially storing data frames descended from the upper layer according to the serial number of the data frame, and a negative response frame receiver 10b for receiving a negative response frame when a negative response frame occurs. ), A receiving buffer state receiver 10d for receiving the state of the receiving side, a circumferential delay timer 10e for driving a predetermined time after transmitting the data, and a frame required when the negative response frame is received. And a data transmission controller 10c which is responsible for retransmission and retransmission of the frame in the transmission buffer and controls the transmission buffer according to the values of the reception buffer status receiver and the circumferential delay timer.

The circumferential delay timer 10e serves as a basis for determining the usefulness of the received L_V (R) value. That is, it is used to know whether the L_V (R) value is transmitted after the transmitted frame arrives at the receiving end. If the L_V (R) value is received before the circumferential delay time expires, the sender may think that the frame sent by him is written before arriving at the receiver, and thus the comparison with the L_V (S) that he recorded is meaningless. At this time, the L_V (S) value compared with the received L_V (R) value should be the value at the time when the diurnal delay timer starts to be driven and is recorded in the list when the diurnal delay timer is driven.

The expiration time of the one week delay timer may be a minimum time or a maximum time until the frame sent from the transmitter arrives at the receiver and returns to the negative response frame. The time includes a transmission delay time, a procedure delay time and a carrier delay time.

The receiving end 20 has a receiving buffer 20a for receiving and storing data, a negative response data generator 20b for outputting data (frames) not received by the received data of the receiving buffer, and the receiving buffer. It comprises a receiving buffer status transmitter 20c for outputting the status of.

FIG. 6 is an example of the operation of the present invention. In this case, the frames lost during transmission are retransmitted using the values of the variables, and L_V (R) smaller than the variable value L_V (S) = 6 is transmitted. That is, three, four and five data frames are transmitted.

More specifically, this is a case in which frames 3, 4, and 5 lost after transmission have been successfully transmitted after frames having frame serial numbers 0, 1, and 2 are successfully transmitted. Since all transmitted frames are lost, the receiving end cannot receive these frames, and still L_V (R) = 3. When the receiving end transmits L_V (R) = 3 to the transmitting end, the transmitting end may know that frames 3, 4, and 5 are lost during transmission as compared to the state where L_V (S) = 6. Therefore, the transmitting end may recognize that the retransmission of these frames is necessary, and the receiving end may retransmit the frame even though the receiving end has not transmitted the negative response frame.

7 is a flowchart illustrating an embodiment using diurnal delay timer and variables for retransmission of a data frame of the present invention.

The transmitting end 10 transmits a data frame to the receiving end 20 (step 70).

After the data frame is transmitted, the round delay timer and the current L_V (S) value are recorded in the list (step 71).

In order to retransmit the transmitted data frame, it is determined whether the week delay timer has expired, and whether there is an L_V (R) value and an L_V (N) value reached after the timer expires, and thus the L_V (R) value and the L_V ( If the N) value is smaller than the current L_V (S), the data frame of the value smaller than the current L_V (S) is retransmitted from the L_V (R) value. (Steps 72,73,74,75).

If the L_V (N) value is smaller than the current L_V (S), the data frame of the L_V (N) value is retransmitted.

If L_V (R) is larger than L_V (S) or retransmitted data of L_V (R) smaller than L_V (S), the operation of the timer for retransmission is stopped and the process returns to the initial process and transmits the data frame. Start a new process (step 76).

As described above, in order to retransmit the data frame, the transmitting end is not transmitted after comparing the newly received L_V (R) value with the L_V (S) value recorded at the time when the delay time is driven. If there are missing frames, resend them. That is, if the received L_V (R) value is smaller than L_V (S), it means that the transmitted frame was not properly transmitted, and thus the transmitting end may spontaneously retransmit the lost frame.

Although the preferred embodiment of the present invention has been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be applied in the same manner by appropriately modifying the above embodiments. That is, the transmitting end may drive these timers as needed using not only one circumferential delay timer but also several circumferential delay timers.

After transmitting a certain amount of data frames, the transmitting end drives an arbitrary N-th delay timer and records the L_V (S) value at the time when the timer is driven. If the L_V (R) value of the newly received buffer after the timer expires is smaller than the recorded L_V (S), the transmitter transmits the serial number L_V (S) -1 from the frame having the serial number L_V (R) -1. It will retransmit up to the frame. At this time, when the L_V (R) value is smaller than the L_V (S) value of the several delayed time delayers, the retransmission is performed only once using the largest value among these L_V (S) values.

In addition, the efficiency of the present invention may vary depending on how often the L_V (N) and L_V (R) values are transmitted to the transmitter. Currently, the IS-707 document transmits the L_V (N) value through the negative response frame or the supplementary frame to extend the serial number of the frame.

In addition, in the present invention, the structure of the frame is changed so that the L_V (R) value is transmitted to these frames in the same way as the L_V (N) value. In addition, since the general data service is bidirectional, data frames are also transmitted from the receiving end to the transmitting end.

Even in this case, the L_V (R) value and the L_V (N) value are transmitted in the data frame so that the reception buffer status can be transmitted. That is, the L_V (R) and L_V (N) values indicating the reception buffer state are put together in the negative response frame, the supplementary frame, and the data frame to be transmitted to the transmitter.

In addition, the L_V (N) information transmitted to extend the serial number of the frame may also be used for simple frame retransmission. If the L_V (N) value received after expiry of the delay timer is smaller than the recorded L_V (S) value, this means that the frame having the serial number of L_V (N) was not transmitted properly. You can retransmit only or retransmit all serial frames smaller than the L_V (S) value.

Accordingly, the above description does not limit the scope of the invention as defined by the limitations of the following claims.

The present invention complements the data frame retransmission executed only by the existing negative response frame, so that the transmitting end can voluntarily retransmit the frame. It can shorten the long delay time caused by the loss of continuous frames that can occur in the wireless environment, and can reduce the number of transmissions of non-response frames, thereby improving channel efficiency and delay time. In addition, in the conventional method, since only the timer needs to be added to the frame structure and the transmitting end, the complexity does not increase greatly in the implementation.

Claims (6)

In a system for transferring data, A transmission buffer for storing input data; A negative response data receiver for receiving a negative response output from the receiving side according to the data output from the transmission buffer, and a receiving buffer state receiver for receiving a state of the receiving side; A week delay timer for driving for a predetermined time after transmitting data; And a data transmission controller for controlling the transmission buffer according to the values of the negative response data receiver, the reception buffer state receiver, and the circumferential delay timer. In a system for transferring data, A transmission buffer for storing input data; A reception buffer for receiving data of the transmission buffer; A negative response data generator for outputting data not received by the received data, and a reception buffer state transmitter for outputting a state of a reception buffer; A negative response data receiver for receiving a negative response output from the receiving side, a receiving buffer state receiver for receiving a state of the receiving side; A week delay timer for driving for a predetermined time after transmitting data; And a data transmission controller for controlling the transmission buffer according to the values of the negative response data receiver, the reception buffer state receiver, and the circumferential delay timer. In a system for transferring data, Driving a timer to time constant; Recording a recognition value of a data bundle transmitted when the timer is driven; Receiving an acknowledgment value of the data bundle received from the receiving buffer returned by the receiving end; and recognizing a value of the data bundle transmitted when the timer is driven when the timer recognizes the received data bundle when the timer expires. And comparing the data and retransmitting the data according to the comparison result. 4. The data retransmission method according to claim 3, wherein the recognition value of the data bundle is a serial number indicating a transmission order. 4. The transmitted data bundle according to claim 3, wherein when a plurality of timers for each data bundle to be transmitted are driven, the recognition value of the received data bundle in the received reception buffer corresponds to the plurality of timers whose operation has expired. If less than the recognition value of the retransmission method characterized in that the retransmission compared to the recognition value of the largest transmitted data bundle. In a system for transferring data, Driving a timer to time constant; Recording a recognition value of a data bundle transmitted when the timer is driven; Receiving a recognition value of an unreceived data bundle in a reception buffer returned by the receiving end; Comparing the recognition value of the received data bundle when the timer expires and the recognition value of the data bundle transmitted when the timer is driven; And retransmitting the data bundle according to the comparison result.