JPH07202852A - Interleave system in communication - Google Patents

Abstract

PURPOSE:To prevent mis-correction or disable correction without increasing a data quality by varying the number of rows and columns for interleaving corresponding to the occurrence state of an error during communication. CONSTITUTION:Information is coded into a code whose error is able to be corrected from a sender side and data subjected to interleaving in which the product of rows and columns for interleaving is constant and the number of the rows and columns is varied depending on a command from a receiver side are sent from the sender side. Upon the receipt of the data, the receiver side implements de-interleaving based on the same number of rows and columns as those at the sender side, output data are decoded and the occurrence state of errors in the received data is detected and a command to revise the number of interleaved lines or the number of rows and columns is generated depending on the error occurrence state and sent to the sender side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interleave system in communication. In recent years, an interleave method has been used as a method for coping with burst errors in communication for transferring information between devices. Particularly in wireless communication using radio waves, light, etc. between the transmitting and receiving devices, burst error can be dealt with by using a code having an error correction capability. The interleave method is also used for communication between a computer main body and an input / output device (keyboard, etc.) that wirelessly communicates with the main body.

Even if data is encoded into an error-correctable code and distributed by interleaving and transmitted, it becomes impossible for the receiving side to perform error correction for a burst error having a long error period in the communication path. . As described above, it is desired to efficiently perform interleaving with respect to the deterioration of the state of the communication path.

[0003]

2. Description of the Related Art FIG. 6 is an explanatory diagram of a conventional interleave system. The conventional interleave method will be described with reference to FIG. 6. The serial time-series data that has been encoded so that an error of a certain number of bits or less can be detected and corrected is shown in FIG. As shown in the above, in the order of K columns, the row direction of the top row of the matrix of L rows (rows), the row direction of the next row, a ₀₀ ,
_{a 01, a 02 ·· a 0K} , a 10, a 11 ·· a 1K, ···, a
_L0, stores data at each position of a _L1 ·· a _LK, when transmitting this, replaced the original order, are transmitted sequentially read in the vertical direction. The order of transmitted data is as follows.

[0004] _{a 00, a 10, ·· a} L0, a 01, a 11 ·· a
_{L1, ··, a 0K ·· a} LK burst errors in a communication path when the data is received on the receiving side (disorders caused by continuous) is generated, for example a _00, a _10, a · · a _L0 Even if there is an error in the data,
When the receiving side restores the original time-series data (called deinterleave), the data of each row (for example, a ₀₀ , a ₀₁ , a ₀₂₎
.. _a0K ), which is a 1-bit error, can be detected and corrected. _{Incidentally,} both while various types have been used as the error detection and correction possible _code, for example, convolutional code (prior to encoding is always associated with the transmitted data, the check code and data for each coded data (A code that represents the information of 1) _{and is} decoded by _a Viterbi decoder.

However, the burst error becomes extremely long. In the example, if an error occurs for a long period exceeding the correction capability, such as when the shaded part (data for three columns of the matrix) becomes a continuous error, the data string after deinterleaving on the receiving side is B.6. The error portion indicated by diagonal lines has 3 consecutive bits, and there is a possibility that the error cannot be corrected or the error is corrected.

As a conventional technique for coping with such a case, the number of rows (the number of rows) of the interleave matrix is fixed and transmitted, and the number of error corrections is counted on the receiving side. There is a method that eliminates the occurrence of consecutive errors after deinterleaving by increasing the number of rows (columns) and reducing the number of error corrections when the number of error corrections decreases, eliminating the uncorrectability in the decoder (special (See Kaihei No. 3-292023).

[0007]

According to the above conventional method, the number of columns (number of stages), which is one of the numerical values of the matrix forming the interleave, is fixed and only the number of stages (number of columns) is changed, so that the number of columns of the communication path is changed. When the state deteriorates, the number of stages (the number of columns) increases and the amount of data to be transmitted increases, so that there is a problem that communication efficiency deteriorates. Further, since the number of columns of interleaving is constant and the number of stages increases, there is a problem that a large memory capacity for transmission / reception is required to support the maximum number of stages. Furthermore, since the amount of data changes as the number of stages increases and decreases, the control for synchronizing becomes complicated.

According to the present invention, the rows and columns of interleaving are made variable according to the error occurrence status during communication by interleaving, but in the communication in which erroneous correction and uncorrectable can be prevented without increasing the data amount. The purpose is to provide an interleave scheme.

[0009]

FIG. 1 is a diagram for explaining the principle of the present invention, in which an interleave matrix is shown. In the figure, L is the number of rows of the current interleave matrix, K is the number of columns, L'is the number of rows of the interleaved matrix that has been changed, and K'is the number of columns that have been changed.

According to the present invention, the interleave matrix size is fixed (K columns × L rows are constant), and the interleave row and column sizes are made variable according to the error occurrence status of the communication path, so that continuation after deinterleaving is performed. It eliminates errors and eliminates erroneous corrections and uncorrectable situations.

[0011]

In FIG. 1, the interleave matrix size is K columns × L rows in a state where there are few errors. The transmitting side performs coding with an error correction code, interleaves with this matrix, and transmits.
On the receiving side, deinterleaving (deinterleaving to restore the original data string) is performed by the same matrix as on the transmitting side, and decoding including error correction is performed.

At that time, an error for each row or a frame check error (an uncorrectable error in the frame) is detected, the error occurrence situation is checked, and if the situation is worse than the standard, the number of rows in the interleave matrix is detected. Increase
Send an instruction to reduce the number of digits from the receiver to the sender, generate an instruction to decrease the number of rows and increase the number of digits if good, and maintain the current state under normal circumstances (no change is meant) ) Generate instructions.

When there is an instruction to increase the number of lines and decrease the number of digits, the transmitting side increases the L lines to L'and K as shown in FIG.
The number of columns is reduced to K ', and transmission is performed using a new interleave matrix. In this case, the deinterleave on the receiving side is also changed to the same row and column values. However, K × L =
K ′ × L ′, and the numerical values of K ′ and L ′ are variable depending on the situation.

When the number of errors is reduced, an instruction to decrease the number of rows and increase the number of columns is sent from the receiving side to the transmitting side, and the number of rows and columns of interleaving is changed according to the instruction. By doing so, it is possible to eliminate the occurrence of consecutive errors and prevent erroneous correction and uncorrectable.

[0015]

FIG. 2 is a block diagram of an embodiment. In FIG. 2, 20 to 23 are transmitters (or encoders), and 20 is an encoder that performs error correction encoding on input information, and various encodings can be used. Here, convolutional code is used. A coding encoder is used. Numeral 21 has a fixed matrix size (L rows × K columns = constant), but the number of rows / columns is variable, and 22 is a row / column that controls the interleave section according to the rows / columns specified by the receiving side. The control unit 23 is a wireless device that wirelessly transmits and receives to and from the receiving device.

24 to 27 are receivers (or decoders)
And 24 is a wireless device for transmitting and receiving wirelessly with the transmitting side, 2
Denoted at 5 is a deinterleave unit for returning the received data to the original data array. Denoted at 26 is a decoder for decoding the deinterleaved data string. In this example, the transmission side performs convolutional coding, and thus the Viterbi decoding is performed. Use a decoder. A row / column control unit 27 receives the error information detected by the decoder, changes the number of rows / columns of the interleaving matrix, notifies the transmission apparatus, and controls the deinterleave unit 25.

FIG. 3 is a control flow of the embodiment. The operation of the embodiment shown in FIG. 2 will be described with reference to the control flow of FIG. The row / column control unit 22 of the transmission device sets the number of rows to L and the number of columns to K as initial values (S1 in FIG. 3).

When transmission information is input to the encoder 20 of FIG. 2, detection coding for error detection and convolutional coding for error correction are performed (S2 in FIG. 3), and the coded data is interleaved by the interleaver 21. To enter. The interleaving unit 21 performs interleaving based on the number of rows L and the number of columns K, which are the initial values set in the row / column control unit 22 in the interleaving matrix (S3 in FIG. 3). The interleaved data is supplied to the wireless device 23 and is wirelessly transmitted from the wireless device 23 via the antenna (see FIG. 3).
S4).

In the receiving device, the wireless signal from the antenna is received by the wireless device 24 (S5 in FIG. 3), and the received data is supplied to the deinterleave unit 25. The row / column control unit 27 of the receiving device is also set with the number of rows L and the number of columns K as initial values, and the numerical values of these rows / columns are input to the deinterleave unit 25. Deinterleaving is performed by the matrix. Interleaving is performed (S6 in FIG. 3).

The deinterleave unit 25 restores the original data string, and at this time, it is detected for each decoded row whether or not an error has occurred (S7 in FIG. 3). It should be noted that this error includes one that may be corrected in the decoder 26 to be executed next.

The deinterleaved data is then input to the decoder 26 for decoding operation (S8 in FIG. 3).
In this example, a Viterbi decoder is used as the decoder 26 and an error of a certain number of bits is corrected, so the decoded data is output to a device (not shown).

However, the decoder 26 cannot correct an error with a certain number of bits or more. In this case, the decoder 2
Reference numeral 6 produces an output indicating whether or not an uncorrectable error (this is called a frame check error) has occurred within a frame (amount of interleave matrix size).

The number of rows in which the error is detected in S7 (which is n) and the frame check error detected in S8 are supplied to the row / column control unit 27. The row / column control unit 27 determines the frame check error and the number of error rows n.
Based on the above, a determination is made to determine the size of the interleaved row / column.

The determination in the row / column control unit 27 is shown in FIG.
The flow is shown in. That is, it is first determined whether or not a frame check error has occurred (S90 in FIG. 4), and if it has occurred, it is determined that the current row number "L" of the current interleaving matrix is increased to a certain number L '. Perform (S91 of FIG. 4).

If there is no frame check error, it is judged whether the number of error occurrence lines n (detected in S7 of FIG. 3) exceeds a predetermined set value a (S92 of FIG. 4). , The current number of lines "L" is maintained (S9
3). If the number of error lines n does not exceed the set value a,
Since the error occurrence is low, the current number of lines "L" is
The number L ″ is reduced by a certain number (S94 in FIG. 4). Note that when the current number of rows of interleaving is L, the set value a is, for example, a = L / 2 or a = L / 4. The value is used.

Number of rows / columns judged (actually only the number of rows)
Is output to the wireless device 24 for transmission as row / column data, and is also supplied to the deinterleave unit 25 to operate with new row / column numerical values. When the number of rows is changed, the deinterleave unit 25 is supplied with the new number of rows and the new number of columns changed correspondingly (S95 in FIG. 4). For example, when the current number of rows L becomes L ′, the new number of columns K ′ becomes (L × K) ÷ L ′.

When row / column data is generated from the row / column control unit 27 and transmitted from the wireless device 24 (S10 in FIG. 3),
It is received by the wireless device 23 of the transmitting device (S11 in FIG. 3).
When the wireless device 23 identifies the reception of the row / column data, it outputs this to the row / column control unit 22. The row / column control unit 22 determines the size of the changed interleaving matrix (the new number of rows and columns) based on the received row / column data (S12 in FIG. 3), and the interleaving unit 21 uses it as control data. Supply. As a result, the interleaving unit 21 interleaves the data to be subsequently input with new rows and columns.

Next, when the number of rows increases because the error does not stop in the control of the number of rows (the number of columns) of interleaving described above, the number of columns becomes smaller, but for each minimum value, The example used will be described.

When the encoding on the transmitting side is convolutional encoding and the receiving side performs Viterbi decoding FIG. 5 shows characteristics in two encodings of convolutional code / Viterbi decoding, and the encoding rate is R = 1/2 ( The number of outputs is 2 when the number of inputs is 1), and the constraint length k represents how many pieces of data that are different in time are needed to obtain an output from the input data. In this example, 3 And seven. The next minimum free distance d represents the minimum Hamming distance required to reach a correct state as the code of the combination, and the correction number t represents the number of correctable bits. Therefore, when the constraint length is 3, an error of up to 2 bits out of 5 bits can be corrected and an error of 3 bits cannot be corrected. Restraint length is 7
The case is also as shown in FIG.

When the coding rate is 1/2, if the burst error can be distributed to 1 bit out of 4 bits, it can be regarded as a non-consecutive 2-bit error in a maximum of 5 bits and can be completely corrected. However, when the occurrence of random errors other than burst errors is taken into consideration, the minimum value of the number of columns (which is represented by L _min ) is a number that satisfies the following condition.

L _min > 4, and [frame size / L _min ] is a natural number When encoding and decoding are performed using a cyclic code (n, k, t), where n is a code length, k is a data length, t Is the correctable number.

When t-fold error correction code, L _min > n / t,
In addition, [frame size / L _min ] is a natural number.

[0033]

According to the present invention, the frame size (the number of K × L) of interleaving is fixed, and the rows and columns are made variable according to the occurrence status of the error in the communication path, so that the continuous error after deinterleaving is eliminated. Can be prevented
It is possible to eliminate erroneous correction and uncorrectable.

Further, since the communication efficiency decreases as the interleave frame size increases, the communication efficiency can be improved as compared with the conventional example described above, and the row / column can be changed particularly when the line quality is good. Is effective.

When Viterbi decoding is used, even if the number of errors in the interleave does not change, it is possible to reduce the probability of erroneous correction by changing the number of matrices to eliminate or reduce the occurrence of continuous errors.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a configuration diagram of an embodiment.

FIG. 3 is a diagram showing a control flow of the embodiment.

FIG. 4 is a diagram showing a flow of row / column determination.

FIG. 5 is a diagram showing two encoding characteristics in the case of convolutional code / Viterbi decoding.

FIG. 6 is an explanatory diagram of a conventional interleave method.

[Explanation of symbols]

 L number of rows of the current interleave matrix K number of columns of the current interleave matrix L'number of rows of the interleaved matrix changed K'number of columns of the interleaved matrix changed

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[Procedure amendment]

[Submission date] January 18, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 5]

[Figure 1]

[Fig. 2]

[Figure 6]

[Figure 3]

[Figure 4]

Claims (4)

[Claims] 1. Encoding information into a code capable of error correction,
The row and column products of the interleaved matrix are constant
The number of columns is variable and interleaved according to the instruction from the receiving side. The data is transmitted from the transmitting side, and when the receiving side receives the data, deinterleaving is performed with the same number of rows and columns as the transmitting side. Decoding the deinterleaved data, detecting the error occurrence status of the received data, and issuing an instruction to change the number of rows or the number of rows / columns of the interleave corresponding to the error occurrence status, An interleaving method in communication, characterized in that the deinterleaving and notification to the transmitting side are performed. 2. An encoder that encodes transmission information into a code capable of error correction on the transmitting side, an interleave unit that interleaves encoded data, and the number of rows / columns of the matrix of the interleave unit. A matrix controller that variably controls the row / column data sent from the receiving side while keeping the product of columns constant, and a wireless device. The receiving side includes a wireless device and a deinterleaving unit that deinterleaves the received data. A decoder that decodes the deinterleaved data and generates error information, and receives the error information from the decoder, and changes the number of rows or the number of rows and columns of the current interleave based on the error occurrence status. Whether or not the number of rows and columns is constant, row / column data indicating a new number of rows or a number of rows and columns is generated, and the deinterleaving is performed. And a matrix control unit for controlling the transmission from the wireless device to the transmission side, and the interleaving method in communication. 3. The matrix control unit on the receiving side according to claim 2, wherein the error information includes frame check error information indicating whether or not an uncorrectable error has occurred in a frame having a constant data length and a constant value. If the number of error occurrence lines in the number of lines is received and a frame check error occurs, increase the number of interleave lines. If no frame check error occurs, determine whether the number of error occurrence lines exceeds a certain value. An interleave method in communication, which determines whether to keep the number of interleave lines at the current value or to reduce the number of lines according to whether or not. 4. The interleave system in communication according to claim 2, wherein an encoder for performing convolutional encoding is provided as the encoder on the transmission side, and a Viterbi decoder is provided as the decoder on the reception side. .