Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
1999-08-20
2003-10-07
Ton, David (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
C714S759000
Reexamination Certificate
active
06631491
ABSTRACT:
This application is a 371 of PCT/JP98/05027 filed on Nov. 09, 1998.
TECHNICAL FIELD
The present invention generally relates to an interleaving technology for improving error correction ability of an error correction code for burst error. More particularly, the present invention relates to an interleaving method, an interleaving device, and a medium which stores an interleaving pattern generating program for improving the effect of the interleaving by increasing the degree of data randomizing.
BACKGROUND ART
In digital transmissions of such as a mobile communications system, the level of received signals varies largely over time by a multipath fading caused by reflections from a building and the like. Therefore, a digital error, such as a burst error, may occur. In addition, in a storing medium of digital systems, such as a compact disc or a hard disk, a digital error such as a burst error may occur due to a scratch, dust or the like on the reading surface of the medium. Thus, various error correction codes are used by various systems. In such an error correction code, for improving the correction ability with respect to the burst error, an interleaving technology is used in concert with the error correction code. The correction ability of the error correction code when a burst error exists depends on the interleaving technology.
In addition, a turbo encoder which uses a high-ability error correction code which has been proposed in recent years includes a plurality of encoders, and each encoder is connected to each other through an interleaver (which carries out interleaving processing), for decreasing the degree of correlation of redundancy system between the encoders. The interleaver is very important for determining the ability of the turbo code.
Therefore, an interleaving method applicable for turbo encoding and transmission systems such as the above-mentioned mobile communication systems using the above mentioned interleaver are required.
As is well known to a person skilled in the art, the purpose of the interleaving method is to randomize the bit sequence of an input bit series and the bit sequence of an out put bit series. The following viewpoint can be used as criteria for evaluating the ability of the interleaving method.
(1) How far apart two successive input bits can be separated in the output series.
(2) How far apart two successive output bits are separated in the input series.
FIG. 1
shows a block interleaving method as a conventional interleaving method.
As shown in
FIG. 1
, data
100
of one frame includes 1152 bits. A matrix
110
has a buffer of N×M (N rows and M columns). The interleaving method is realized such that M bit data is written in the direction of the row, for example, like a vector
115
shown as a diagonally shaded area A, and N bit data is read out in the direction of the column shown as a diagonally shaded area B. By evaluating the interleaving method in terms of the above mentioned criteria, it is recognized that
(1) two successive input bits can not be separated farther apart than N bits in an interleaved output series
130
, and
interleavers generated by repeating the second step once or a plurality of times or from each of interleavers generated by the first step, and outputting a data series.
The above-mentioned invention may be configured such that an interleaving method for inputting a data series of a unit length and outputting an interleaved series of the unit length, includes:
a first step of writing the data series to a first interleaver in one direction;
a second step of reading out column data or row data from the first interleaver, writing the read out data to a second interleaver, which has a size different from a size of the first interleaver, in one direction, and repeating the reading out column data or row data and the writing the read out data column by column or row by row;
repeating a third step of performing the second step wherein each of a plurality of the second interleavers generated by the second step is regarded as the first interleaver, and reading out data from each of interleavers generated by repeating the third step or by performing the second step, and outputting a data series.
The above-mentioned interleaving method may be configured such that an interleaving method for inputting a data series of a unit length and outputting an interleaved series of the unit length, includes:
a first step of writing the data series to a first interleaver in one direction;
a second step of reading out column data or row data from the first interleaver, writing the read out data to a second interleaver, which has a size different from a size of the first interleaver,
(2) two successive output bits are separated as far apart as at least M bits in the input series.
However, in the above-mentioned interleaving method, an input bit series is written in the row direction in order of time in the input bit series, and the written data is read out in the column direction also in order of time in the input bit series. Therefore, data is written/read only once in order of time in each of the processes. Therefore, the effect of the interleaving is low, and the performance of the randomizing is limited to the above-mentioned degree even with the N×M buffer.
DISCLOSURE OF THE INVENTION
The present invention is achieved in view of the above-mentioned points. A first objective of the present invention is to provide an interleaving method for improving the effect of the interleaving, comparing with the case of reading and writing one by one in order of time, by applying a process of changing a sequence repeatedly after carrying out a process of reading or writing to a buffer once.
To achieve the above-mentioned objective, according to the present invention, an interleaving method for inputting a data series of a unit length and outputting an interleaved series of the unit length, includes:
a first step of writing data of the data series to a first interleaver, reading out the data column by column or row by row from the first interleaver, and writing the data to a plurality of second interleavers;
a second step of reading out the data from each of the second interleavers, and writing the data to one or a plurality of third interleavers as necessary, and
reading out the data from each of in one direction, and repeating the reading out column data or row data and the writing the read out data column by column or row by row;
a third step of reading out data column by column or row by row from each of interleavers generated by the second step, and writing the data to an interleaver which has a size the same as the size of the first interleaver, and
reading out data from the interleaver generated by the third step, and outputting a data series.
In the above configuration, the interleaving method includes:
a fourth step of performing the second step and the third step wherein the interleaver generated by the third step is regarded as the first interleaver, reading out data from an interleaver generated by repeating the fourth step once or a plurality of times, and outputting a data series.
The interleaving method may be configured such that an interleaving method for inputting a data series of a unit length and outputting an interleaved data series of the unit length, includes:
storing a plurality of interleaving patterns in a table beforehand;
applying one of the interleaving patterns to the input data series by referring to the table and outputting data, and
repeating a step of applying one of the interleaving patterns to the output data, and outputting the interleaved data series.
In the above mentioned configuration, an interleaving pattern is stored in the table according to the interleaving method as claimed in one of claims
1
-
4
.
According to the above mentioned invention, because a process of changing sequence is applied repeatedly after carrying out a process of reading or writing to a buffer once, the effect of interleaving can be improved comparing with the case of reading and writing one by one in order of time.
The se
Shibutani Akira
Suda Hirohito
NTT Mobile Communications Network Inc.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ton David
LandOfFree
Interleaving method, interleaving apparatus, and recording... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Interleaving method, interleaving apparatus, and recording..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Interleaving method, interleaving apparatus, and recording... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3153135