KR101848199B1 - data storage systems and method - Google Patents

Abstract

A data storage system and method are disclosed. The data storage system includes: an encoder for converting input data into a code word; a storage unit for storing the converted code word; and a decoder for converting the code word stored in the storage unit into output data, wherein the encoder converts 9-bit input data into the code word of a 3 x 4 matrix. Accordingly, the present invention can reduce inference between 2D symbols.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

Embodiments of the present invention relate to a data storage system and method capable of reducing two-dimensional inter-symbol interference (ISI) generated in Bit-Patterned Media Recording (BPMR) and efficiently storing two-dimensional data.

Bit-Patterned Media Recording (BPMR) is a next-generation magnetic recording system for hard disk drives (HDDs) to extend storage density. BPMR is a competitive technology that can extend area density compared to other proposed technologies. In BPMR, each channel bit is stored in an isolated island, and magnetic grains are strongly coupled. There is a non-magnetic domain or a weak magnetic domain between the particles in the isolated island, and the isolated island is surrounded by the magnetic domain controlled by the patterning procedure.

On the other hand, BPMR has many error factors, such as inter-symbol interference (ISI) and inter-page interference (IPI). In particular, 2D inter-symbol interference (2D ISI) is a major cause of degrading the quality of the data being searched. Many studies have been conducted to solve these problems.

In order to solve the problems of the related art as described above, in the present invention, two-dimensional inter-symbol interference (2D ISI) generated in Bit-Patterned Media Recording (BPMR) A data storage system and method are proposed.

Other objects of the invention will be apparent to those skilled in the art from the following examples.

According to a preferred embodiment of the present invention, there is provided a data storage system including: an encoder for converting input data into a codeword; A storage unit for storing the converted code word; And a decoder for converting the codeword stored in the storage into output data, wherein the encoder converts 9-bit input data into a codeword of a 3x4 matrix.

Wherein the code word of the 3x4 matrix that can be transformed from the 9-bit input data is 4096 and the encoder is configured to convert only the code word having a minimum hamming distance between code words of 2 or more out of 4096 code words Can be used.

Wherein the code words of the 3x4 matrix that can be transformed from the 9-bit input data are 4096, the bits constituting each of the code words of the 3x4 matrix have a high value or a low value, A codeword having a 2D ISI pattern is not used among the 4096 codewords, and the codeword having the 2D ISI pattern is not used in any one of the bits constituting the 3x4 matrix The value of the bit of the up / down / right / left / right bits of any one bit may be different from the value of the bit of the up / down / left /

Wherein the code words of the 3x4 matrix that can be transformed from the 9-bit input data are 4096, the bits constituting each of the code words of the 3x4 matrix have a high value or a low value, A codeword having no ITI (Intertrack Interference) effect is used among the 4096 codewords, and the codeword having the ITI effect has a value of one bit in each of the edge columns of the 3x4 matrix May have a value different from all of the values of the bits above and below one of the bits.

According to another embodiment of the present invention, there is provided a data storage system comprising: an encoder for converting 9-bit input data into a code word of a 3x4 matrix; A storage unit for storing the converted code word; And a decoder for converting the codeword stored in the storage unit into output data, wherein 4096 codewords of the 3x4 matrix that can be converted from the 9-bit input data are included, and the code of the 3x4 matrix Wherein each of the bits constituting each word has a high value or a low value and the encoder uses 512 codewords among 986 codewords satisfying predetermined conditions among the 4096 codewords, A second condition that the code word has no 2D ISI pattern and a third condition that the codeword does not have an ITI effect. / RTI >

According to another embodiment of the present invention, there is provided a method of storing data in a processor, comprising: encoding an input data into a codeword; A storing step of storing the converted codeword; And a decoding step of converting the stored codeword into output data, wherein the encoding step converts 9-bit input data into a codeword of a 3x4 matrix.

According to the present invention, there is an advantage in that the two-dimensional intersymbol interference can be reduced.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

FIG. 1 is a diagram showing a schematic configuration of a data storage system according to an embodiment of the present invention.
2 is a flowchart illustrating a data storage method according to an embodiment of the present invention.
3 is a diagram illustrating a concept of an operation of an encoder according to an embodiment of the present invention.
4 is a diagram illustrating 512 codewords used in an encoder according to an embodiment of the present invention.
5 is a diagram for explaining the 2D ISI pattern and the ITI effect.

As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. In this specification, the terms "comprising ", or" comprising "and the like should not be construed as necessarily including the various elements or steps described in the specification, Or may be further comprised of additional components or steps. Also, the terms "part," " module, "and the like described in the specification mean units for processing at least one function or operation, which may be implemented in hardware or software or a combination of hardware and software .

Various embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

The present invention relates to a data storage system using a modulation coding technique to reduce two-dimensional inter-symbol interference (ISI) generated in a bit-patterned media recording (BPMR) and efficiently store two- A modulation code technique used in the present invention is a 9/12 2D modulation code for modulating all 9-bit input data (information sequences) into a 3x4 2D output array, that is, output code words of 12 symbols Technique.

FIG. 1 is a diagram showing a schematic configuration of a data storage system using the above-described modulation coding technique according to an embodiment of the present invention.

Referring to FIG. 1, a data storage system 100 according to an exemplary embodiment of the present invention includes, for example, an encoder 110, a controller 120, and a decoder 130 as a BPMR data storage system.

2 is a flowchart illustrating a data storage method according to an embodiment of the present invention. Here, the method of storing data may be performed in a device including a processor, for example, the data storage system 100 shown in FIG.

Hereinafter, the function of each component and the operation performed in each step will be described in detail.

In step 210, the encoder 110 performs the function of converting the input data into a codeword. That is, the encoder 110 converts 9-bit input data into a 2-dimensional matrix, that is, a code word of a 3x4 matrix composed of 12 bits.

In step 220, the storage unit 120 stores the converted codewords. To this end, a horizontal equalizer 121, a vertical equalizer 122, A horizontal SOVA 123, a vertical SOVA 124, and an average value calculation unit 125. [

More specifically, the signal output to the encoder 110 is transmitted to the storage unit 120 through a data channel (e.g., a BPMR channel). At this time, additive white Gaussian noise (AWGN) is generated in the data channel and the readback signal r [p, q] corresponding to the output signal of the encoder 110 that has passed through the data channel is stored in the storage unit 120).

The horizontal equalizer 121 and the vertical equalizer 122 perform equalization on the readback signal r [p, q]. That is, the horizontal equalizer 121 performs horizontal direction equalization on the readback signal r [p, q] to output the output signal z _h [p, q], and the vertical equalizer 1212 And performs equalization in the vertical direction with respect to the readback signal r [p, q] to output the output signal z _v [p, q].

The horizontal SOVA 123 detects the inter-symbol interference using the output signal z _h [p, q] of the horizontal equalizer 121 and the vertical SOVA 124 detects the output signal z _v [p, q] is used to detect inter-symbol interference. The average value calculation unit 125 calculates an average value for the output signal s _h [p, q] of the horizontal SOVA 123 and the output signal s _v [p, q] of the vertical SOVA 124.

Also, at step 230, the decoder 130 performs the function of converting the stored codeword into output data.

That is, the decoder 130 applies the decoding procedure of the proposed modulation code based on the concept of Euclidean distance. For the codeword received at the storage unit 120, the decoder 130 calculates the Euclidean distance for all codewords belonging to the codeword set using the following equation (1).

는 i번째 수신된 코드워드, c_i는 코드워드 세트 내의 선택된 코드워드 세트에 속하는 i번째 코드워드,

는 i번째 수신된 코드워드의 j번째 심볼, c_ij는 i번째 코드워드의 j번째 심볼을 각각 의미한다. here,

Is the i-th received codeword, c _i is the i-th code word belonging to a set of selected code words in the code word set,

Denotes a j-th symbol of an i-th received codeword, and c _ij denotes a j-th symbol of an i-th codeword.

Hereinafter, the encoder 110, which is a characteristic component of the present invention, will be described in more detail.

3 is a diagram illustrating a concept of an operation of the encoder 110 according to an embodiment of the present invention.

Referring to FIG. 3, the encoder 110 converts a 9-bit sequence of user data into a 12-bit code word (array structure) of a 3x4 matrix. The converted code words (2D arrays) are arranged sequentially on the page.

The code words of the 12-bit 3x4 matrix that can be transformed from the 9-bit input data may be 4096 (= 2 ¹² ), and the bits constituting each of the code words of the 3x4 matrix are high values 1) or a low value (for example, 0 or -1).

In this case, the encoder 110 can use 986 codewords satisfying predetermined conditions among 4096 codewords. At this time, since the input data is 9 bits, the encoder 110 can use 512 (2 ⁹ ) codewords out of 986 codewords. At this time, the selection of 512 codewords out of the 986 codewords can be performed randomly or in the order that the encoder 110 outputs the codewords in a short period of time. FIG. 4 shows 512 codewords used in the encoder 110. FIG.

According to one embodiment of the present invention, predetermined conditions are i) a first condition in which a minimum hamming distance between codewords is at least 2, ii) a second condition in which the codeword does not have a 2D ISI pattern, and iii) and a third condition that does not have an intertrack interference effect.

In this case, the Hamming distance means a number in which the bit values do not coincide with each other between binary codes having the same number of bits. For example, if A is 101011 and B is 110010, Hamming distance of A and B is 3. The codewords shown in FIG. 4 have a Hamming distance of at least 2 between codewords.

Also, a code word having a 2D ISI pattern is a code word having a value different from that of any one of the bits constituting the 3x4 matrix, Lt; / RTI > This is as shown in Fig. 5 (a).

The codeword having the ITI effect may be a codeword in which the value of one bit in each edge column of the matrix has a value different from that of any of the bits above or below the bit. This is as shown in FIG. 5 (b), and it is a codeword that has an ITI effect when bit a and bit c both have a value of 1, or both b and d have a value of -1 .

 That is, the encoder 110 encodes a codeword that satisfies at least one of the first condition, the second condition, and the third condition, preferably a codeword that satisfies the first condition, the second condition, and the third condition It can be used in conversion.

The predetermined condition will be described in more detail as follows.

There are 2D modulation codes with low-pass constraints among the encoding schemes to improve the performance of the data storage system affected by the 2D ISI. At this time, the above-mentioned constraint condition generates a modulation code block, and the modulation code block is not composed of a component having a high spatial frequency. A 2D output arrangement having content with a high spatial frequency is defined as containing a specific bit of the center surrounded by many contiguous bits of opposite values. In this case, a particular bit in the center tends to be incorrectly detected.

For example, referring to FIG. 5A, if the target bit '1' (high bit) is surrounded by a plurality of bits '-1' (low bit) -1 '(low bit), or when the target bit' -1 '(low bit) is surrounded by a plurality of bits' 1' (high bit) (Low bit) may be erroneously detected as bit '1' (high bit) (2D ISI pattern). That is, as described above, if the value of any one of the bits constituting the matrix which is the code word output from the encoder 110 is different from the value of the bits of the upper, lower, left, If there is a value, the error is likely to occur. Therefore, the encoder 110 must solve the problem of the 2D ISI pattern.

On the other hand, not only the removal of the 2D ISI pattern but also the ITI effect should be eliminated. Referring to FIG. 5 (b), as described above, the ITI effect is generated in the edge column of the matrix by setting a value of one bit to a value different from all bits of the bits above and below the one bit It means to have. That is, if the value of the middle bit of the first column of the 3x4 matrix is equal to the value of the upper / lower bit of the middle bit of the first column, and the value of the middle bit of the fourth row of the 3x4 matrix is equal to the value of the upper / The corresponding codeword has an ITI effect. In other words, when the value of the bit at the position (2, 1) of the 3x4 matrix is the bit value at the position (1, 1) of the 3x4 matrix and the bit value at the position (3, (2, 4) of the 3x4 matrix is the same as the bit value at the (1, 4) position of the 3x4 matrix and the bit value of the 3x4 matrix of the 3x4 matrix 3, 4), the corresponding codeword is a codeword having no ITI effect. FIG. 5 (c) shows the worst case of the codeword having the ITI effect.

Therefore, the encoder 110 of the present invention outputs the code words satisfying the following three conditions (the priority levels of the three conditions are decremented in order) as described above. That is, the selected codeword must: i) have a minimum hamming distance between code words of 2 or more, ii) do not include a 2D ISI pattern, and iii) do not have an ITI effect. Since the number of codewords satisfying all three conditions is 986, and the input data is 9 bits, the encoder 110 can use 512 (2 ⁹ ) codewords out of 986 codewords. At this time, 9-bit input data is mapped to a code word of 512 in 1: 1.

In summary, the present invention is advantageous in that the two-dimensional intersymbol interference generated in BPMR and the like can be reduced and the two-dimensional data can be efficiently stored by encoding using the above three conditions.

In addition, embodiments of the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Examples of program instructions, such as magneto-optical and ROM, RAM, flash memory and the like, can be executed by a computer using an interpreter or the like, as well as machine code, Includes a high-level language code. The hardware devices described above may be configured to operate as one or more software modules to perform operations of one embodiment of the present invention, and vice versa.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and limited embodiments and drawings. However, it should be understood that the present invention is not limited to the above- Various modifications and variations may be made thereto by those skilled in the art to which the present invention pertains. Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (7)

In a data storage system,
An encoder for converting the input data into a codeword;
A storage unit for storing the converted code word; And
And a decoder for converting a codeword stored in the storage into output data,
The encoder converts input data of 9 bits into 4096 code words which are code words of a 3x4 matrix and uses only code words whose minimum hamming distance between code words is 2 or more among the 4096 code words during code word conversion Lt; / RTI > delete The method according to claim 1,
The bits constituting each of the code words of the 3x4 matrix have a high value or a low value,
Wherein the encoder does not use a codeword having a 2D ISI (inter-symbol interference) pattern among the 4096 codewords during codeword conversion,
The codeword having the 2D ISI pattern is characterized in that the value of any one of the bits constituting the 3x4 matrix has a value different from the value of the bits of the up / down / left / right of any one of the bits Lt; / RTI > The method according to claim 1,
The bits constituting each of the code words of the 3x4 matrix have a high value or a low value,
Wherein the encoder uses a codeword that does not have an ITI (intertrack interference) effect among the 4096 codewords during codeword conversion,
Wherein the codeword having the ITI effect has a value of one bit in each of the edge columns of the 3x4 matrix has a different value from that of bits above and below the bit of the one bit. system. In a data storage system,
An encoder for converting 9-bit input data into a code word of a 3x4 matrix;
A storage unit for storing the converted code word; And
And a decoder for converting a codeword stored in the storage into output data,
The code words of the 3x4 matrix that can be transformed from the 9-bit input data are 4096, the bits constituting each of the code words of the 3x4 matrix have a high value or a low value,
Wherein the encoder uses 512 codewords among 986 codewords satisfying predetermined conditions among the 4096 codewords,
Wherein the predetermined condition is a first condition that a minimum hamming distance between codewords is 2 or more, a second condition that the codeword does not have a 2D ISI pattern, and a third condition that the codeword has no ITI effect Data storage system. A method of storing data in a processor,
An encoding step of converting input data into a codeword;
A storing step of storing the converted codeword; And
And a decoding step of converting the stored codeword into output data,
Wherein the encoding step converts the 9-bit input data into 4096 code words, which are code words of a 3x4 matrix, and uses only code words having a minimum hamming distance of 2 or more among the 4096 code words, And storing the data. A computer-readable recording medium recording a program for performing the method of claim 6.

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