JPH10290216A - Method for error-correction decoding and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance error correcting capability by deciding error-corrected packets by majority and correcting an error about a newly constituted packet. SOLUTION: First error correcting means 1a to 1c correct errors of encoded packets up to (m) bits with correction codes capable of correcting an up to (n)-bit error. A majority decision means 2 decides packets by majority to constitute one packet. A 2nd error correcting means 3 corrects errors of encoded packets up to (n) bits with correction codes capable of correcting the up to (n)-bit error. Namely, the 1st error correcting means 1a to 1c correct only up to errors having bits less than the maximum correcting capability of the added error correction codes, so the probability of error correction is low and then an increase in the number of errors is suppressed, thereby enhancing the final error correcting capability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an error correction decoding method and apparatus for performing decoding processing using a plurality of error correction encoded duplicate packets in communication, broadcasting and storage of digitized data. It is.

[0002]

2. Description of the Related Art In recent years, when digitized data is transmitted or stored, particularly important data, such as header information relating to a compressed signal of a video or an address of an optical disk, in a transmission path or a recording medium having many errors. For data, etc., a plurality of data are transmitted redundantly or multiplexed on an optical disk, and the receiving device or the reproducing device performs error correction decoding processing using a plurality of packets of the same information that has been subjected to error correction coding, and transmits the data. And errors at the time of recording are suppressed. Further, even when the transmitting apparatus transmits a single packet that has been subjected to error correction coding, the receiving apparatus receives the single packet as a plurality of packets from different transmission paths by receiving the packet in a diversity manner. An error is corrected and decoded using the plurality of packets to suppress an error occurring during transmission.

A conventional example of an error correction decoding method for important data multiplexed on a recording medium such as an optical disk is disclosed in Japanese Patent Application Laid-Open No. 62-298058.

The operation principle of the conventional error correction decoding method will be described with reference to FIG. Generally, important data such as address data is k-overwritten on the recording medium with an error correction code added.
The case where overwriting is performed will be described. That is, the first packet UT1 is composed of data D1 such as an address and an error correction code E1, and so on, UT2 is composed of D2 and E2, and UT3 is composed of D3 and E3. The three packets UT1, UT2, and UT3 written in such a triple manner are reproduced, and the majority of the data portions D1, D2, and D3 is determined, and one data Dx is selected. The majority decision at this time may be made in accordance with the coincidence of the data values themselves, or may be made for each bit of each data. Also,
The majority of the error correction codes E1, E2, and E3 are similarly determined and one code Ex is selected. The data Dx thus obtained and the error correction code Ex are combined to form one new packet, and this packet is subjected to a predetermined error correction decoding process to read data. .

[0005]

However, in the above-mentioned conventional error correction decoding method, when the method is applied to a transmission line or a recording medium having an error rate higher than the bit error rate that can be decoded by this method, a more powerful method is required. It is necessary to add an error correction code or to transmit or accumulate a large number of duplicated packets, resulting in a disadvantage that the efficiency of information transmission and accumulation is deteriorated.

As a method of enhancing the correction capability of the above-described conventional error correction decoding method, an error correction is performed by using a plurality of overlapping packets of the same information encoded by an error correction code capable of correcting an error of up to n bits. Is performed, for each of a plurality of packets, an error of up to n bits is corrected first, and a majority of the plurality of error-corrected packets is taken to form a new one packet. With respect to this new one packet, A method of correcting an error up to n bits can be considered. Normally, error correction calculates the syndrome of an error-correction-encoded packet, searches a correspondence table of the syndrome and error bit positions up to n bits, inverts the bits at the bit positions indicated in the table, and performs error correction. Do. However, when an error correction code capable of correcting an error of up to n bits is used to correct an error of up to n bits which is the maximum correction capability, a syndrome when an error of more than n bits occurs in a certain code word is as follows. There is a high possibility that the code word coincides with the syndrome when an error of up to n bits occurs in another code word. In such a case, an incorrect code word is erroneously corrected. In the case of errors that cannot be corrected by the above-mentioned conventional method, there are many cases where more than n bits occur in one packet. In such an error, in the error correction up to n bits before the majority decision, the bits of the originally correct information are used. Since the position is erroneously inverted and erroneously corrected to an incorrect codeword, the number of erroneous bits increases, and the final error correction rate deteriorates.

An object of the present invention is to enhance the error correction capability of such an error correction decoding method without deteriorating the efficiency of information transmission and storage.

[0008]

In order to solve this problem, an error correction decoding method according to the present invention uses an error correction code which can correct an error up to n bits (n is an integer of 2 or more). In the error correction decoding method for performing error correction using a plurality of overlapping packets of the same information, an error of up to m bits (m is a positive integer smaller than n) is corrected for each of the plurality of encoded packets, and m A new packet is formed by taking a majority decision of a plurality of packets in which errors of up to bits have been corrected, and errors of up to n bits are corrected in the newly formed packet.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an error correction decoding apparatus according to the present invention. One error correction means, 2 is a majority decision means for forming one packet by taking a majority decision of a plurality of packets, and 3 is a maximum of n bits for a packet encoded with an error correction code capable of correcting an error of up to n bits. This is a second error correction means for correcting an error.

The operation of the error correction decoding method will be described. FIGS. 1 and 2 show a case where a (15,7) BCH code capable of correcting an error of up to 2 bits is used as an error correction code to be used, and decoding is performed using three packets obtained by encoding the same information. 2 will be described. That is, n = 2 and m = 1. (1) (15, 7)
It receives three packets in which the same information is encoded with the BCH code, or reads out the same from the recording medium. ((A) of FIG. 2) (2) These three packets contain errors in the transmission path or the recording medium, and these three packets are converted by the first error correction means 1a, 1b, and 1c up to 1 bit. Correct the error. ((B) of FIG. 2) Here, FIG.
In the above, the cross mark indicates the bit position where an error has occurred. Since packet 1 contains a 3-bit error, packet 2 contains a 1-bit error, and packet 3 contains a 5-bit error, Packets 1 and 3 are output as they are as uncorrectable. Packet 2 has a 1-bit error and is corrected and output. (3) The majority of the three packets output from the first error correction means 1a, 1b, and 1c is determined by the majority decision means 2 for each same bit, and one new packet is formed and output. ((C) of FIG. 2) Here, in FIG. 2, since two errors remain in the same bit of the packet 1 and the packet 3, an error remains in the position even if a majority decision is taken. (4) The new packet output by the majority decision means 2 is corrected by the second error correction means 3 for an error of up to 2 bits. ((D) of FIG. 2) In FIG. 2, since the number of error bits is 2 bits, (15, 7)
Two-bit error correction is normally performed by the BCH code and output. On the other hand, when an error as shown in FIG. 2 is mixed, in the conventional method, a majority decision is directly performed on the three packets received or read. Therefore, when a new packet is formed by the majority decision means, a 3-bit error remains. Therefore, the last (15, 7) BCH code cannot be corrected normally. In addition, when correcting an error of up to 2 bits (n = 2) before the majority decision, there is a high possibility that a packet 1 or a packet 3 in which a 3-bit error or a 5-bit error has occurred is erroneously corrected. Here the number of errors increases,
Instead, the final error correction rate is reduced.

In this embodiment, the description has been made using the (15, 7) BCH code capable of correcting an error of up to 2 bits. However, if the code can correct an error of 2 bits or more, the present invention can be applied to this method. It is possible. Also, the case where decoding is performed using three packets has been described, but the present invention is applicable as long as the number of packets is two or more. Further, although the majority decision means takes a majority decision for each bit, it is also possible to take a majority decision using the information bit and the correction bit as one unit.

[0012]

Since the present invention is configured as described above, it has the following effects.

[0013] The information transmission and storage efficiencies are the same as those of the conventional method, the pattern errors that cannot be corrected by the conventional method can be corrected normally, and the first error correction means adds the error correction code. Since errors are corrected only up to the number of bits smaller than the maximum correction capability, the probability of erroneous correction is low, the increase in the number of errors can be suppressed, and the final error correction capability can be enhanced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an error correction decoding device according to the present invention.

FIG. 2 is an explanatory diagram of the operation principle of the error correction decoding method of the present invention.

FIG. 3 is an explanatory diagram of an operation principle of a conventional error correction decoding method.

[Explanation of symbols]

 1a, 1b, 1c First error correction means 2 Majority decision means 3 Second error correction means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takushi Katsura 1006 Kazuma Kadoma, Kadoma, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. An error correction decoding method for performing error correction using a plurality of packets of the same information encoded with an error correction code capable of correcting an error of up to n bits (n is an integer of 2 or more). Error of up to m bits (m is a positive integer smaller than n) for each of the
Error correction decoding, wherein a majority of a plurality of packets in which errors of up to bits have been corrected is taken to form a new packet, and errors of up to n bits are corrected in the newly formed packet. Method. 2. An error correction decoding apparatus for performing error correction using a plurality of packets of the same information encoded by an error correction code capable of correcting an error up to n bits (n is an integer of 2 or more). A first error correction unit for correcting an error of up to m bits (m is a positive integer smaller than n) for each of the plurality of packets, and a majority decision of the plurality of packets corrected by the first error correction unit. Error correction decoding comprising a majority decision means for newly forming one packet and a second error correction means for correcting an error of up to n bits in one packet constituted by the majority decision means apparatus.