JP2000078234A - Number determination method and data communication device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To easily determine a number used for transmitting / receiving a frame signal, such as a frame number or a retransmission request number, regardless of success or failure of reception of a received frame. SOLUTION: A transmitting station transmits a frame signal in which a number is described by a corresponding predetermined unique word, and a receiving station extracts a unique word from a predetermined area of the received frame signal, and extracts the extracted unique word. Calculates the autocorrelation of the unique word corresponding to all the numbers used by the transmitting station, identifies the unique word having the maximum autocorrelation value exceeding a predetermined threshold, and sets the number corresponding to the unique word to the frame by the transmitting station. Determine as the number described in the signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a number determination method and a data determination method in which a receiving station determines a number described in a predetermined area of a frame signal by the transmitting station between a transmitting station and a receiving station transmitting and receiving a frame signal. Related to a communication device.

In particular, even when a frame signal reception error occurs, for example, a number used for realizing data communication, a frame number used for data frame order management, and a retransmission request used for a retransmission request for an error frame. The present invention relates to a number determining method used for determining a number and a data communication device.

[0003]

2. Description of the Related Art When a transmitting station performs automatic retransmission of data to a receiving station using forward and return paths, type 1 hybrid ARQ and type 2 hybrid ARQ are used as error control techniques combining automatic retransmission and error correction. is there.

FIG. 11 shows the concept of a type 1 hybrid ARQ. The transmitting station transmits a data frame to which a check symbol for error correction is added in advance. The receiving station
Error correction is performed on an error added in a communication channel or the like using a check symbol added to a received data frame. In the example shown in FIG. 11, since the error correction capability is 1 bit, if two or more errors occur, transmission fails and retransmission is required. If one bit or no error occurs, the transmission is successful.

FIG. 12 shows the concept of the type 2 hybrid ARQ. The transmitting station creates a data frame and a check symbol for performing error correction of the data frame from the data frame, and stores them in a buffer provided in the transmitting station. First, the transmitting station transmits a data frame.
If the receiving station detects an error when receiving the data frame, the receiving station stores the data frame in a buffer provided in the receiving station and requests the transmitting station to retransmit the data frame.

[0006] The transmitting station knows from the retransmission request that the transmission of the data frame has failed, and transmits the check symbols stored in the buffer. The receiving station receives the check symbols and, if no error is included in the received check symbols, generates the data frame from the check symbols. If an error is detected, the receiving station corrects the error of the received data frame using the data frame and the check symbol stored in the buffer. If the error has been corrected, the transmission of the data frame is successful. On the other hand, if the error correction fails, the receiving station discards the data frame stored in the buffer and stores a new check symbol in the buffer. Then, the receiving station requests the transmitting station to retransmit the data frame. The above process is repeated until the transmission of the data frame is successful.

In such a conventional automatic retransmission method,
By using the frame number, it is possible to avoid erroneous recognition of a data frame due to a timeout, determine a received data frame, and determine a retransmission request frame. The frame number is continuously assigned to the data frame, where the modulo number is M.

FIG. 13 shows a data frame and a retransmission request frame used when performing data communication. The data frame has at least an area 1 for accommodating user data, an area 5 for accommodating a frame number, and an area 3 for accommodating an error detection code. The retransmission request frame has at least an area 6 for accommodating a retransmission request number group including one or more N frames (1 ≦ N ≦ maximum modulo number) and an area 3 for accommodating an error detection code.

FIG. 14 shows a basic procedure of a conventional number determination method. (1) shows the procedure for assigning a number in the transmitting station, and (2) shows the procedure for determining the number in the receiving station. The transmitting station assigns a number (S62), constructs a frame containing the number in a predetermined area (S63), and transmits the frame (S64).
Upon receiving the frame (S66), the receiving station performs error detection on the received frame using the error detection code (S6).
7). Then, a determination is made on the error detection result of the received frame (S68), and if an error is detected, the number determination fails (S69). If no error is detected, the determination of the number is successful (S70).

FIG. 15 shows a basic procedure of a conventional frame number determination method. (1) numbering at the transmitting station,
(2) shows the procedure for determining the number at the receiving station. The transmitting station assigns a frame number (S72), constructs a data frame (FIG. 13 (1)) containing the frame number in area 5 (S73), and transmits the data frame (S74). Upon receiving the data frame (S76), the receiving station detects an error in the received data frame using the error detection code in area 3 (S77). Then, a determination is made on the error detection result of the received data frame (S78), and if an error is detected, the determination of the frame number fails (S79).
If no error is detected, a frame number is extracted from the area 5 (S80), and the determination of the frame number is successful (S81).

By the way, type 1 hybrid ARQ
Discards the received data frame if the error in the received data frame cannot be corrected.
Therefore, there is no problem in applying the frame number determination method to the type 1 hybrid ARQ. On the other hand, in the type 2 hybrid ARQ, even when an error is included in the received data, the receiving station stores the received data frame or the check symbol in the buffer and uses the retransmitted check symbol or data frame together. Then, error correction is performed. Therefore, even when an error is included in the received data frame, it is necessary to determine the frame number. That is, when performing type 2 hybrid ARQ,
The method for determining the frame number is not sufficient. Therefore, by adding a check symbol such as an error detection code or an error correction code to the frame number of the data frame, the frame number is determined regardless of an error in the received data frame.

FIG. 16 shows a data frame in which a check symbol is added to a frame number or a retransmission request number and a retransmission request frame. The data frame has at least an area 1 for accommodating user data, an area 7 for accommodating a frame number and a check symbol used for error correction thereof, and an area 3 for accommodating an error detection code. The retransmission request frame has at least an area 8 for storing a retransmission request number group including a retransmission request number and a check symbol used for error correction thereof, and an area 3 for storing an error detection code.

FIG. 17 shows a basic procedure of a conventional frame number determination method (with error correction added). (1) shows the procedure for assigning a number in the transmitting station, and (2) shows the procedure for determining the number in the receiving station. The transmitting station assigns a frame number (S83),
A check symbol is added to the frame number (S84), a data frame (FIG. 16 (1)) containing the frame number and the check symbol in the area 7 is constructed (S85), and the data frame is transmitted (S86).

When the receiving station receives the data frame (S88), it extracts the frame number and check symbol contained in the area 7 (S89), and corrects the error of the frame number using the check symbol (S90). Then, it is determined whether or not the error in the frame number can be corrected (S91). If the error cannot be corrected, the determination of the frame number fails (S92). If error correction is possible, the determination of the frame number is successful (S93).

Next, the case where the receiving station that has received the data frame requests the transmitting station to retransmit the data frame will be described. Here, a receiving station that transmits a retransmission request frame will be described as a transmitting station.

FIG. 18 shows a basic procedure of a conventional retransmission request number determination method. (1) numbering at the transmitting station,
(2) shows the procedure for determining the number at the receiving station. The transmitting station multiplexes the retransmission request number into N frames (1 ≦ N ≦ modulo number) based on the past reception history and assigns the retransmission request number (S102). Then, a retransmission request frame (FIG. 13 (2)) containing the retransmission request number in area 6 is constructed (S103), and the retransmission request frame is transmitted (S104).

When the receiving station receives the retransmission request frame (S106), it performs error detection on the received retransmission request frame using the error detection code in area 3 (S107). And
A determination is made on the error detection result of the received retransmission request frame (S108), and if an error is detected, the retransmission request number determination fails (S109). If no error is detected, the retransmission request number is extracted from the area 6 (S110), and the retransmission request number is successfully determined (S111).

When an error occurs in a retransmission request frame, it is impossible to determine all retransmission request numbers, unnecessary retransmission increases, and throughput in the data communication system decreases. Therefore, as shown in FIG.
The retransmission request number is protected by adding a check symbol such as an error detection code or an error correction code to all the retransmission request numbers in the retransmission request frame.

FIG. 19 shows a basic procedure of a conventional retransmission request number determination method (with error correction). (1) shows the procedure for assigning a number in the transmitting station, and (2) shows the procedure for determining the number in the receiving station. The transmitting station assigns a retransmission request number for N frames (S113), adds a check symbol used for error correction to each retransmission request number (S114), and stores the retransmission request number and the check symbol in area 8. The retransmission request frame (FIG. 16 (2)) is constructed (S115), and the retransmission request frame is transmitted (S116).

Upon receiving the retransmission request frame (S118), the receiving station extracts the retransmission request number and the check symbol contained in the area 8 (S119), and corrects the error of the retransmission request number using the check symbol (S119). S120). Then, it is determined whether or not the error in the retransmission request number can be corrected (S121). If the error cannot be corrected, the retransmission request number determination fails (S122). If error correction is possible, the retransmission request number is successfully determined (S123). Then, error correction is performed on all the retransmission request numbers accommodated in the area 8 of the reception retransmission request frame (S124), and thereafter, the operation for determining the retransmission request number is terminated (S125).

FIG. 20 shows an example of the configuration of a conventional data communication apparatus for determining a number. (1) shows the configuration of the transmitting station, and (2) shows the configuration of the receiving station. In the figure, a number used for data communication is assigned to input data by a number assigning section 31, and an error correction check symbol is assigned to the number by an error correction encoding circuit 32. The frame construction unit 33 constructs a data frame or a retransmission request frame, and the transmitter 34 transmits the frame. The number of the frame received by the receiver 41 is extracted by the reception number extraction unit 42, error correction is performed on the number extracted by the decoding circuit 43, and the number is determined by the number determination unit 44.

[0022]

To perform error correction using an error correction code for a number used in realizing data communication, such as a frame number of a data frame and a retransmission request number of a retransmission request frame, an equation: Must be solved, and the hardware becomes complicated. Further, as the error correction capability increases, the hardware scale increases exponentially, and the processing delay also increases. Further, when an error equal to or more than the error correction capability occurs, it is not possible to determine a number used for realizing data communication such as a frame number and a retransmission request number.

The present invention provides a number determination method and a data communication device that can easily determine a number used for transmitting and receiving a frame signal, such as a frame number and a retransmission request number, irrespective of success or failure of reception of a received frame. The purpose is to do.

[0024]

Generally, a code having orthogonality such as a unique word can uniquely specify a unique word by utilizing autocorrelation even when an error occurs in a communication line. it can.

The number determination method and the data communication apparatus according to the present invention provide a unique word which is a code word having orthogonality, periodicity and randomness, and a number used for communication such as a frame number and a retransmission request number. Mapped to one,
A frame including a unique word is transmitted / received between the transmitting station and the receiving station, and the number is determined with high accuracy by utilizing autocorrelation.

That is, the transmitting station transmits a frame signal in which a number is described by a corresponding unique word. The receiving station extracts a unique word from a predetermined area of the received frame signal, calculates an autocorrelation between the extracted unique word and a unique word corresponding to all the numbers used by the transmitting station, and has a maximum autocorrelation value. A unique word exceeding a predetermined threshold is specified, and a number corresponding to the unique word is determined as a number described in the frame signal by the transmitting station.

[0027]

FIG. 1 shows the structure of a data frame and a retransmission request frame. (1) is the data frame,
(2) indicates a retransmission request frame.

The data frame has at least an area 1 for storing user data, an area 2 for storing a unique word representing a frame number, and an area 3 for storing an error detection code. The receiving station extracts the unique word contained in the area 2 of the received data frame, and uses the function of obtaining the autocorrelation of the unique word possessed by the receiving station, by using the extracted unique word and all frame numbers used by the transmitting station. The autocorrelation between the corresponding unique words is obtained, and a search for the unique word having the maximum autocorrelation value is performed. Then, the receiving station previously sets a threshold value for determining the frame number for the maximum autocorrelation value in an analog manner, performs a soft decision, and determines the frame number.

The retransmission request frame includes at least an area 4 containing a unique word indicating a retransmission request number from one frame to N frames (1 ≦ N ≦ maximum modulo number) and an area 3 containing an error detection code of the retransmission request frame. Have. The receiving station of the retransmission request frame (the transmitting station of the data frame) extracts the unique word contained in area 4 of the received retransmission request frame, and determines the retransmission request number in the same manner.

FIG. 2 shows a basic procedure of the number determination method of the first aspect. (1) shows the number assignment in the transmitting station, and (2) shows the procedure for determining the number in the receiving station. The transmitting station assigns a unique word representing the number (S1), constructs a frame including the number (unique word) (S2), and transmits the frame (S3).

When the receiving station receives the frame (S
6) The autocorrelation between the unique word of the received frame and the unique word representing the number is calculated (S7). And
When the calculation of the autocorrelation with the unique words corresponding to all the numbers used by the transmitting station is completed (S8), the maximum autocorrelation value is determined from among them (S9), and the maximum autocorrelation value is used when the number is determined. It is determined whether it is equal to or more than the threshold α (S10).
If the value is equal to or larger than the threshold value α, the unique word having the maximum autocorrelation value is specified, and the number corresponding thereto is determined (S1
2). If the number is less than the threshold value α, the unique word cannot be specified, so that the number determination fails (S11).

FIG. 3 shows the relationship between the number of error bits and the autocorrelation value. The M sequence [52] is used as a unique word. The autocorrelation R _ab between the unique word A and the unique word B is as follows: R _ab = (B1−B2) / BT (1) B1: Equal number of bits between the unique word A and the unique word B B2: The unique word A and the unique word B BT: Total bit number (B1 + B2). When an error correction code is used, the correction capability is fixedly determined. However, as shown in FIG. 3, it can be seen that the present method can flexibly cope with errors during reception by changing the threshold α. .

In FIG. 3, when the threshold value α is set to 0.65, an error in the communication path is detected, for example, in 31 bits of the unique word.
If the error rate is 10 bits or less (the error rate is 0.3 or less), it can be said that a unique word can be specified up to a 5-bit error. That is, if the error rate of the communication channel worsens, the autocorrelation result may indicate another unique word, and the number determination method of the present invention cannot be used.

FIG. 4 shows the number (frame number) of claim 2
The basic procedure of the confirmation method is shown. (1) shows the procedure for assigning a frame number in the transmitting station, and (2) shows the procedure for determining the frame number in the receiving station. The transmitting station describes the frame number with a unique word (S22), constructs a data frame including the frame number (unique word) (S23), and transmits the data frame (S24).

When the receiving station receives the data frame (S26), it extracts a unique word corresponding to the frame number contained in area 2 of the received data frame (S2).
7) The autocorrelation between the unique word and the unique word representing the frame number is calculated (S28). When the calculation of the autocorrelation with the unique words corresponding to all the frame numbers used by the transmitting station is completed (S29), the maximum autocorrelation value is determined from the calculated values (S30), and the maximum autocorrelation value determines the frame number. It is determined whether the value is equal to or more than the threshold value α for determination (S31). If the difference is equal to or larger than the threshold α, the unique word having the maximum autocorrelation value is specified, and the frame number corresponding to the unique word is determined (S33). If the difference is less than the threshold value α, the unique word cannot be specified, so that the determination of the frame number fails (S32).

FIG. 5 shows an example of frame number assignment (transmitting station) according to claim 2. An M sequence is used as a unique word. The transmitting station expresses the frame number with a unique word according to the frame number / unique word conversion table. AR
The modulo number when performing Q is seven. FIG. 5A shows a data frame # 0 of the frame number 0. Frame number 0
Is "1100101",
It is accommodated in area 2 of data frame # 0. Fig. 5 (2)
Indicates data frame # 1 of frame number 4. The unique word for frame number 4 is “01011110”
And are accommodated in area 2 of data frame # 1.

FIG. 6 shows an example of frame number determination (receiving station) according to claim 2. The receiving station has the same frame number / unique word conversion table as the transmitting station. In FIG. 6, the threshold α for determining the frame number is 0.7. Since the unique word stored in area 2 of received data frame # 0 contains a 1-bit error,
“1100100”. The autocorrelation value between “1100100” and the unique words corresponding to all the frame numbers used by the transmitting station is obtained from equation (1). As a result, the autocorrelation with the unique word “1100101” becomes 0.714, which is the maximum. The threshold for determining the frame number is α = 0.7
Thus, the unique word is specified as “1100101”, and the received frame number is determined to be 0. Thus, even when an error occurs in the received data frame, the frame number can be determined.

FIG. 7 shows a basic procedure of a method for determining a number (retransmission request number) according to claims 3 and 4. (1) shows a procedure for assigning a retransmission request number at a transmitting station, and (2) shows a procedure for determining a retransmission request number at a receiving station. Transmitting station (receiving station for data frame)
Describes the retransmission request number with a unique word (S42),
A retransmission request frame including the retransmission request number (unique word) is constructed (S43), and the retransmission request frame is transmitted (S44).

Upon receiving the retransmission request frame (S46), the receiving station (data frame transmitting station) extracts a unique word corresponding to the retransmission request number accommodated in area 4 of the received retransmission request frame (S47). The autocorrelation between the unique word and the unique word representing the retransmission request number is calculated (S48). When the calculation of the autocorrelation with the unique word corresponding to all the retransmission request numbers used by the transmitting station is completed (S49), the maximum autocorrelation value is determined from among them (S49).
50), it is determined whether or not the maximum autocorrelation value is equal to or larger than a threshold α for determining the retransmission request number (S51). If it is equal to or greater than the threshold α, the unique word having the maximum autocorrelation value is specified, and the corresponding retransmission request number is determined (S53).
If the number is less than the threshold value α, the unique word cannot be specified, so that the retransmission request number determination fails (S52). Further, area 4 of the reception / retransmission request frame
The retransmission request numbers based on the autocorrelation are determined for all the unique words accommodated in (1) (S54), and the process is terminated (S55).

FIG. 8 shows an example (transmission station) of assigning a retransmission request number in the third and fourth aspects. An M sequence is used as a unique word. Here, the modulo number is set to 7, and the retransmission request frame can be multiplexed with four retransmission request numbers.
The transmitting station expresses the retransmission request number with a unique word according to the retransmission request number / unique word conversion table. FIG. 8 shows retransmission request frames having retransmission request numbers 0, 1, 2, and 3. The unique word for retransmission request number 0 is “110”
0101 ", and are accommodated in area 4 of the retransmission request frame. Similarly, unique words corresponding to retransmission request numbers 1, 2, and 3 are sequentially accommodated in area 4.

FIG. 9 shows a retransmission request number determination example (receiving station) according to the third and fourth aspects. The receiving station has the same retransmission request number / unique word conversion table as the transmitting station. In FIG. 9, the threshold α for determining the retransmission request number is 0.7. The unique word stored at the beginning of the area 4 of the received retransmission request frame is “1100100” because it contains a 1-bit error. “1100100”
Then, the autocorrelation value between the unique word corresponding to all the retransmission request numbers used by the transmitting station is calculated by equation (1). as a result,
The autocorrelation with the unique word "1100101" is 0.71
4 and the maximum. The threshold for determining the retransmission request number is α
From = 0.7, the unique word is specified as "1100101", and the received retransmission request number is determined to be 0. The receiving station performs the same operation on the remaining unique words contained in area 4 to determine the retransmission request number. Thus, even when an error occurs in the reception retransmission request frame, the retransmission request number can be determined.

FIG. 10 shows a configuration example of the data communication apparatus according to claim 5. (1) shows the configuration of the transmitting station, and (2) shows the configuration of the receiving station. In the figure, the input data is described by a unique word with a number used for data communication by the unique word assigning unit 11. The frame construction unit 12 constructs a data frame or a retransmission request frame, and
3 transmits the frame. From the frame received by the receiver 21, a unique word is extracted by a received unique word extraction unit 22. The autocorrelation calculation unit 24 extracts all the unique words used as numbers from the unique word group 23 and calculates an autocorrelation value with the extracted unique words. Unique word determination unit 25
Specifies a unique word based on the autocorrelation calculation result and determines the corresponding number.

The calculation of the autocorrelation of the unique word in the autocorrelation calculating section 24 can be realized only by, for example, EXOR processing, and the processing does not depend on the number of error bits. Also, by applying a matched filter to the received unique word, hardware for calculating the autocorrelation value of the unique word can be realized with a simple and small circuit scale.

[0044]

As described above, the number determination method and the data communication apparatus of the present invention can easily determine the frame number, the retransmission request number, and the like even when the received frame contains an error. Becomes Therefore, it is possible to efficiently realize an error control technique in which determination of a frame number is indispensable, such as the above-described retransmission control technique of the type 2 hybrid ARQ, in terms of both hardware scale and software scale.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a data frame and a retransmission request frame.

FIG. 2 is a flowchart showing a basic procedure of the number determination method according to claim 1;

FIG. 3 is a diagram showing a relationship between the number of error bits and an autocorrelation value.

FIG. 4 is a flowchart showing a basic procedure of a number (frame number) determination method according to claim 2;

FIG. 5 is a diagram showing a frame number assignment example (transmitting station) according to claim 2;

FIG. 6 is a diagram showing an example of frame number determination (receiving station) according to claim 2;

FIG. 7 is a flowchart showing a basic procedure of a method for determining a number (retransmission request number) according to claims 3 and 4;

FIG. 8 is a diagram showing an example of a retransmission request number assignment (transmission station) according to claims 3 and 4;

FIG. 9 is a diagram showing a retransmission request number determination example (receiving station) according to claims 3 and 4;

FIG. 10 is a block diagram showing a configuration example of a data communication device according to claim 5;

FIG. 11 is a diagram illustrating the concept of a type 1 hybrid ARQ (when 1-bit error correction is possible).

FIG. 12 is a diagram illustrating the concept of a type 2 hybrid ARQ.

FIG. 13 is a diagram showing a configuration of a conventional data frame and a retransmission request frame.

FIG. 14 is a flowchart showing a basic procedure of a conventional number determination method.

FIG. 15 is a flowchart showing a basic procedure of a conventional frame number determination method.

FIG. 16 is a diagram showing a configuration of a conventional data frame and a retransmission request frame (with error correction added).

FIG. 17 is a flowchart showing a basic procedure of a conventional frame number determination method (adding error correction).

FIG. 18 is a flowchart showing a basic procedure of a conventional retransmission request number determination method.

FIG. 19 is a flowchart showing the basic procedure of a conventional retransmission request number determination method (with error correction).

FIG. 20 is a block diagram showing a configuration example of a conventional data communication device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Unique word assignment part 12 Frame construction part 13 Transmitter 21 Receiver 22 Received unique word extraction part 23 Unique word group 24 Autocorrelation calculation part 25 Unique word determination part 31 Number assignment part 32 Error correction coding circuit 33 Frame construction part 34 Transmitter 41 Receiver 42 Received number extraction unit 43 Decoding circuit 44 Number determination unit

Continuing on the front page (72) Inventor Tomoyoshi Ohno 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Hiroyuki Otsuka 3- 19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Telephone Co., Ltd. F term (reference) 5K014 AA01 BA01 FA03 5K034 AA06 DD01 HH01 HH02 HH08 HH09 HH11 HH12 MM03 MM39 NN13 5K047 AA11 HH01 HH15 HH44 LL15

Claims (5)

[Claims] 1. A number determining method in which a receiving station determines a number described in a predetermined area of a frame signal by a transmitting station between a transmitting station and a receiving station that transmits and receives a frame signal, wherein the transmitting station comprises: The receiving station extracts a unique word from a predetermined area of the received frame signal, and transmits the extracted unique word and a total number used by the transmitting station. Calculate the autocorrelation with the unique word corresponding to the number, identify the unique word whose autocorrelation value is greater than a predetermined threshold, and describe the number corresponding to the unique word in the frame signal by the transmitting station. A number determination method, wherein the number is determined as a number. 2. A number determining method in which a transmitting station determines a frame number described in a predetermined area 2 of a data frame between the transmitting station and a receiving station that transmits and receives the data frame, the transmitting station comprising: Transmitting a data frame in which the frame number is described by a corresponding predetermined unique word, the receiving station extracts a unique word from a predetermined area 2 of the received data frame, and transmits the extracted unique word and the transmission Calculate the autocorrelation with the unique word corresponding to all frame numbers used by the station, identify the unique word whose autocorrelation value is greater than a maximum and exceeds a predetermined threshold, and obtain the frame number corresponding to the unique word from the transmitting station. A number determination method, wherein the number is determined as a frame number of a transmitted data frame. 3. One of the stations transmits a data frame with a specific frame number between two opposing stations, and the other station adds a frame number of a data frame that could not be received as a retransmission request number. The transmitting station (the other station) of the data communication device, which transmits the retransmission request frame described above and one of which retransmits the data frame having the frame number corresponding to the retransmission request number, is described in the predetermined area 4 of the retransmission request frame. The receiving station (one of the stations) determines the retransmission request number, the transmitting station transmits a retransmission request frame in which the retransmission request number is described by a corresponding unique word. Extracts a unique word from a predetermined area 4 of the received retransmission request frame, and extracts the extracted unique word and all retransmission requests used by the transmitting station. Auto-correlation with the unique word corresponding to the signal, the auto-correlation value specifies the unique word whose maximum value exceeds a predetermined threshold, and the transmitting station sets the retransmission request number corresponding to the unique word by the retransmission request frame. A number determination method characterized in that the number is determined as a retransmission request number described in (1). 4. The number determination method according to claim 3, wherein the retransmission request frame describes a plurality of unique words respectively corresponding to the plurality of retransmission request numbers, and the receiving station stores each of the plurality of unique words by itself. A number determination method characterized by identifying by correlation and determining a retransmission request number corresponding to each unique word as a retransmission request number described in a retransmission request frame by a transmitting station. 5. A retransmission request number between two opposing stations, wherein one station transmits a data frame with a specific frame number, and the other station does not receive a data frame with a frame number. A retransmission request frame, wherein one of the stations retransmits a data frame having a frame number corresponding to the retransmission request number, wherein the transmitting station transmitting the data frame or the retransmission request frame includes: A unique word assigning unit that describes a frame number or a retransmission request number described in an area of the corresponding unique word, respectively, wherein the receiving station that receives the data frame or the retransmission request frame performs a predetermined A receiving unique word extracting unit for extracting a unique word from the area of A unique word group accommodating unique words corresponding to all numbers used by the bureau, and a self-calculating unit that calculates an autocorrelation between the unique word extracted by the received unique word extracting unit and each unique word accommodated in the unique word group. A correlation calculation unit for identifying a unique word whose autocorrelation value is greater than a predetermined threshold and determining a number corresponding to the unique word as a number described by the transmitting station in the data frame or the retransmission request frame; A data communication device comprising a unique word determination unit.