CN112804026A - Frequency and time frequency interleaving method and system in OFDM system - Google Patents

Frequency and time frequency interleaving method and system in OFDM system Download PDF

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CN112804026A
CN112804026A CN201911106581.6A CN201911106581A CN112804026A CN 112804026 A CN112804026 A CN 112804026A CN 201911106581 A CN201911106581 A CN 201911106581A CN 112804026 A CN112804026 A CN 112804026A
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frequency interleaving
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CN112804026B (en
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田金凤
李睿嘉
卞鑫
王芳
李明齐
封松林
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Shanghai Advanced Research Institute of CAS
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0056—Systems characterized by the type of code used
    • H04L1/0071—Use of interleaving
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
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Abstract

The invention provides a method and a system for interleaving frequency and time frequency in an OFDM system, which comprises the following steps: writing data with the length of L into an interleaver with M rows and N columns according to columns or an interleaver with M columns and N rows according to rows; when writing into an interleaver with M rows and N columns, sequencing the row sequence number of the interleaver according to a first preset rule, sequentially reading out each p columns of data according to the sequenced row sequence number, and sequentially reading out the rest columns of data when the last rest columns are less than p columns to form frequency interleaved data, wherein p is more than or equal to 1 and less than or equal to N; when writing into the interleaver with M columns and N rows, sequencing the column sequence numbers of the interleaver according to a second preset rule, sequentially reading every p rows of data according to the sequenced column sequence numbers, and sequentially reading the remaining rows of data when the last remaining row number is less than p rows to form frequency interleaved data, wherein p is more than or equal to 1 and less than or equal to N. The frequency and time frequency interleaving method and system in the OFDM system can effectively improve the interleaving performance when one symbol in the OFDM system bears a non-integer number of code blocks.

Description

Frequency and time frequency interleaving method and system in OFDM system
Technical Field
The invention relates to the technical field of transmission communication, in particular to a frequency and time frequency interleaving method and system in an OFDM system.
Background
In a wireless communication system, especially a wireless broadcasting system, in order to improve the fault tolerance of the system, it is necessary to implement error-free transmission at the receiving end as much as possible. In general, time interleaving techniques are employed to combat the problem of channel interference. Because the probability of errors occurring in the adjacent information units at the same time is generally high, block errors are easy to form and are not easy to correct. Therefore, time interleaving, which is a task of scrambling and transmitting adjacent information units as much as possible, becomes an important link for solving the stability and data accuracy of a communication system.
The block interleaving changes the distribution of data under a certain rule, increases the distance between adjacent original data and reduces the probability of continuous errors. When considering writing a matrix of size M × N in columns, the number of rows M represents the number of cells of one code block, the number of columns N represents the number of code blocks, and N is equal to or greater than 1.
In an Orthogonal Frequency Division Multiplexing (OFDM) system, one subframe carries an integer number of coded code blocks. But the number of code blocks carried by one symbol is not necessarily exactly an integer. When the code blocks that can be carried by one OFDM symbol are not an integer number of code blocks, how to design time-frequency interleaving to effectively improve the time diversity gain is a problem to be solved at present.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a method and a system for interleaving frequency and time in an OFDM system, which can effectively improve interleaving performance when one symbol in the OFDM system carries a non-integer number of code blocks.
To achieve the above and other related objects, the present invention provides a frequency interleaving method in an OFDM system, comprising the steps of: writing data with the length of L into an interleaver with M rows and N columns according to columns or an interleaver with M columns and N rows according to rows; when writing into an interleaver with M rows and N columns, sequencing the row sequence number of the interleaver according to a first preset rule, sequentially reading out each p columns of data according to the sequenced row sequence number R, and sequentially reading out the rest columns of data when the last rest columns are less than p columns to form frequency interleaved data, wherein p is more than or equal to 1 and less than or equal to N; when writing into an interleaver with M columns and N rows, sequencing the column sequence numbers of the interleaver according to a second preset rule, sequentially reading each p rows of data according to the sequenced column sequence number R, and sequentially reading the remaining rows of data when the last remaining row number is less than p rows to form data after frequency interleaving, wherein p is more than or equal to 1 and less than or equal to N.
In an embodiment of the present invention, L is an integer multiple or a fractional multiple of the number of code blocks in the OFDM system.
In one embodiment of the present invention, M ═ L, N ═ 1, and p ═ 1.
In one embodiment of the present invention, N ═ max { N ═ NCB,Q}，
Figure BDA0002271503480000021
1≤p≤NCBIn which N isCBDenotes the number of code blocks carried by one subframe in the OFDM system, Q denotes the number of symbols of one subframe,
Figure BDA0002271503480000022
indicating rounding up.
In an embodiment of the present invention, the first and second substrates are,
Figure BDA0002271503480000023
correspondingly, the invention provides a frequency interleaving system in an OFDM system, which comprises a writing module, a first processing module and a second processing module;
the writing module is used for writing data with the length of L into an interleaver with M rows and N columns according to columns or writing the data into an interleaver with M rows and N rows according to rows;
the first processing module is used for sorting the row serial numbers of the interleaver according to a first preset rule when the interleaver with M rows and N columns is written in, sequentially reading out each p columns of data according to the sorted row serial numbers R, and sequentially reading out the rest columns of data when the number of the last rest columns is less than p columns so as to form data after frequency interleaving, wherein p is more than or equal to 1 and less than or equal to N;
the second processing module is used for sorting the column sequence numbers of the interleavers according to a second preset rule when the interleavers with M columns and N rows are written in, sequentially reading every p rows of data according to the sorted column sequence numbers R, and sequentially reading the rest rows of data when the last rest row number is less than p rows to form frequency interleaved data, wherein p is more than or equal to 1 and less than or equal to N.
The invention provides a time-frequency interleaving method in an OFDM system, which comprises the following steps:
frequency interleaving is carried out on K data sequences with the length of L according to the frequency interleaving method in the OFDM system;
writing the data sequence after frequency interleaving into a data block Y of qL rows and K/Q columns according to columns, wherein Q is more than or equal to 1 and less than or equal to Q, and Q represents the symbol number of a subframe in the OFDM system;
circularly shifting each row of the data block Y leftwards according to a preset offset to obtain a data block Z of qL rows and K/q columns;
when Q/Q is equal to 1, moving the rear qL/Q row of the data block Z from the lower side to the right side, and outputting a data block W formed by time interleaving of L rows and K columns; and when Q/Q is smaller than 1, the data block Z is the data block W after time interleaving.
In an embodiment of the present invention, when frequency interleaving is performed, the sequence of the row sequence numbers of the interleaver after sorting is unchanged.
In an embodiment of the present invention, the preset offset s is mod (R-1, K/q), where R is a row sequence number sorted when frequency interleaving is performed according to a first preset rule or a column sequence number sorted when frequency interleaving is performed according to a second preset rule.
Correspondingly, the invention provides a time-frequency interleaving system in an OFDM system, which comprises a frequency interleaving module, a writing module, a cyclic shift module and an output module;
the frequency interleaving module is used for performing frequency interleaving on K data sequences with the length of L according to the frequency interleaving method in the OFDM system;
the writing module is used for writing the data sequence after the frequency interleaving into a data block Y of qL rows and K/Q columns according to columns, Q is more than or equal to 1 and less than or equal to Q, and Q represents the symbol number of a subframe in the OFDM system;
the cyclic shift module is used for carrying out cyclic shift on each row of the data block Y leftwards according to a preset offset to obtain a data block Z of qL rows and K/q columns;
the output module is used for moving the rear qL/Q row of the data block Z from the lower side to the right side when Q/Q is equal to 1, and outputting the data block W after time interleaving of L rows and K columns; and when Q/Q is smaller than 1, the data block Z is the data block W subjected to time interleaving.
As described above, the frequency and time-frequency interleaving method and system in the OFDM system of the present invention have the following advantages:
(1) not only the time-frequency interleaving when one OFDM symbol bears an integral multiple of code blocks is supported, but also the time-frequency interleaving when one OFDM symbol bears a fractional multiple of code blocks is supported;
(2) a plurality of time-frequency interleaving modes with different configurations are provided, and the flexibility and the scene adaptability are high;
(3) the time frequency interleaving performance is effectively improved.
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FIG. 1 is a flow chart of a method of time interleaving in an OFDM system according to an embodiment of the present invention;
FIG. 2 is a diagram of a time interleaving method in an OFDM system according to a first embodiment of the present invention;
FIG. 3 is a diagram of a time interleaving method in an OFDM system according to a second embodiment of the present invention;
FIG. 4 is a diagram illustrating an exemplary time interleaving system in an OFDM system;
FIG. 5 is a flowchart illustrating a time-frequency interleaving method in an OFDM system according to an embodiment of the present invention;
FIG. 6 is a diagram illustrating a time-frequency interleaving method in an OFDM system according to a first embodiment of the present invention;
FIG. 7 is a diagram illustrating a time-frequency interleaving method in an OFDM system according to a second embodiment of the present invention;
FIG. 8 is a schematic structural diagram of a time-frequency interleaving system in an OFDM system according to an embodiment of the present invention;
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.
It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than the number, shape and size of the components in practical implementation, and the type, amount and ratio of the components in practical implementation may be changed arbitrarily, and the layout of the components may be complicated.
The frequency and time frequency interleaving method and the system in the OFDM system are compatible with time interleaving and time frequency interleaving of an OFDM symbol bearing integral multiple or fractional multiple code blocks, effectively improve the interleaving performance and have strong practicability.
As shown in fig. 1, in an embodiment, the frequency interleaving method in the OFDM system of the present invention includes the following steps:
step S11 is to write data of length L into an interleaver of M rows and N columns by columns or an interleaver of M columns and N rows by rows.
In one embodiment, for a data sequence x { x ] of length L1,…,xLAnd writing an interleaver with M rows and N columns in sequence according to the columns.
In another embodiment, for a data sequence x { x ] of length L1,…,xLAnd writing the interleaver into M columns and N rows in sequence according to the rows.
In an embodiment of the present invention, L is an integer multiple or a fractional multiple of the number of code blocks in the OFDM system, so that a situation that one OFDM symbol carries an integer multiple or a fractional multiple of code blocks can be compatible.
Setting the length of one code block as C, then L ═ CNCB/Q，NCBThe number of code blocks carried by one subframe in the OFDM system is represented, and Q represents the number of symbols of one subframe.
Step S12, when writing into the interleaver with M rows and N columns, sorting the row sequence number of the interleaver according to a first preset rule, then sequentially reading each p columns of data according to the sorted row sequence number R, and sequentially reading the remaining columns of data when the last remaining columns are less than p columns to form frequency interleaved data, wherein p is more than or equal to 1 and less than or equal to N.
Specifically, the first preset rule may be expressed by the following formula:
Figure BDA0002271503480000041
wherein R isiThe row sequence number at the ith bit after sequencing is represented;
Figure BDA0002271503480000042
representing a preset interval; m is more than or equal to i and more than or equal to 2, R1＝1，
Figure BDA0002271503480000043
Which means that the rounding is made up,
Figure BDA0002271503480000044
indicating a rounding down. When the length of the written data is not exactly a multiple of M, i.e. N is a fraction, padding is performed at the end of the input data
Figure BDA0002271503480000045
The individual padding data are rewritten to the interleaver and skipped when reading out the data.
Specifically, the first preset rule may also be RiDenoted by i.
In one embodiment of the present invention, M ═ L, N ═ 1, and p ═ 1. This represents frequency interleaving of data by symbol.
In another embodiment of the present invention, N ═ max { N ═ NCB,Q}，
Figure BDA0002271503480000051
1≤p≤NCBIn which N isCBDenotes the number of code blocks carried by one subframe in the OFDM system, Q denotes the number of symbols of one subframe,
Figure BDA0002271503480000052
indicating rounding up. This represents frequency interleaving of data by code block. Typically, the Q number takes the value 1 or 2. Preferably, the first and second electrodes are formed of a metal,
Figure BDA0002271503480000053
specifically, when data is read, the data is sequentially read in units of p columns of data. And sequentially reading the last remaining data of less than p columns according to the sequence, thereby obtaining the data after frequency interleaving.
And step S13, when writing into the M columns and N rows of interleavers, sorting the column sequence numbers of the interleavers according to a second preset rule, sequentially reading out each p rows of data according to the sorted column sequence numbers R, and sequentially reading out the remaining rows of data when the last remaining row number is less than p rows to form frequency interleaved data, wherein p is more than or equal to 1 and less than or equal to N.
Specifically, the second preset rule may be expressed by the following formula:
Figure BDA0002271503480000054
wherein R isiThe column number at the ith bit after sorting is represented;
Figure BDA0002271503480000055
representing a preset interval; m is more than or equal to i and more than or equal to 2, R1＝1，
Figure BDA0002271503480000056
Which means that the rounding is made up,
Figure BDA0002271503480000057
indicating a rounding down. When the length of the written data is not exactly a multiple of M, i.e. N is a fraction, padding is performed at the end of the input data
Figure BDA0002271503480000058
The individual padding data are rewritten to the interleaver and skipped when reading out the data.
In particular, the second preset rule may also be RiDenoted by i.
In one embodiment of the present invention, M ═ L, N ═ 1, and p ═ 1. This represents frequency interleaving of data by symbol.
In another embodiment of the present invention, N ═ max { N ═ NCB,Q}，
Figure BDA0002271503480000059
1≤p≤NCBIn which N isCBDenotes the number of code blocks carried by one subframe in the OFDM system, Q denotes the number of symbols of one subframe,
Figure BDA00022715034800000510
indicating rounding up. This represents frequency interleaving of data by code block. Typically, the Q number takes the value 1 or 2. Preferably, the first and second electrodes are formed of a metal,
Figure BDA00022715034800000511
specifically, when reading data, the data are sequentially read in units of p-line data. And sequentially reading the last remaining data of less than p rows according to the sequence, thereby obtaining the data after frequency interleaving.
The frequency interleaving method in the OFDM system of the present invention is further described below by specific embodiments.
The number of subframes K of data X to be interleaved is set to 1, and the number of symbols Q of one subframe is set to 1, in which caseOnly frequency interleaving is done. Setting the code block number N borne by one subframe CB3, the length C of one code block is 7, and the length L of encoded data carried by one symbol is 21. Wherein, 1 to 7 belong to the first code block of the subframe (or symbol), 8 to 14 belong to the second code block, and 15 to 21 belong to the third code block.
Example one
The number of rows M, L, N, 1, and p of the frequency interleaver are taken as L, N, and p, 1. The results of the data obtained before and after frequency interleaving according to the new line sequence number after sequencing the line sequence numbers are shown in fig. 2.
Example two
Taking the number of rows M-C-N of frequency interleaverCBThe data results before and after frequency interleaving are shown in fig. 3, where p is 3.
As shown in fig. 4, in an embodiment, the frequency interleaving system in the OFDM system of the present invention includes a writing module 41, a first processing module 42, and a second processing module 43.
The writing module 41 is configured to write data with a length of L into an interleaver with M rows and N columns by columns or an interleaver with M columns and N rows by rows.
The first processing module 42 is connected to the writing module 41, and configured to sort the row sequence numbers of the interleaver according to a first preset rule when writing into the interleaver with M rows and N columns, sequentially read out each p columns of data according to the sorted row sequence numbers R, and sequentially read out the remaining rows of data when the last remaining rows of data is less than p columns, so as to form frequency-interleaved data, where p is greater than or equal to 1 and is less than or equal to N.
The second processing module 43 is connected to the writing module 41, and configured to sort the column sequence numbers of the interleaver according to a second preset rule when writing into the interleaver with M columns and N rows, sequentially read out data of every p rows according to the sorted column sequence numbers R, and sequentially read out remaining data of every row when the last remaining row is less than p rows, so as to form frequency-interleaved data, where p is greater than or equal to 1 and less than or equal to N.
The structures and principles of the writing module 41, the first processing module 42, and the second processing module 43 correspond to the steps in the frequency interleaving method in the OFDM system one to one, and therefore are not described herein again.
It should be noted that the division of the modules of the above apparatus is only a logical division, and the actual implementation may be wholly or partially integrated into one physical entity, or may be physically separated. And the modules can be realized in a form that all software is called by the processing element, or in a form that all the modules are realized in a form that all the modules are called by the processing element, or in a form that part of the modules are called by the processing element. For example: the x module can be a separately established processing element, and can also be integrated in a certain chip of the device. In addition, the x-module may be stored in the memory of the apparatus in the form of program code, and a certain processing element of the apparatus may call and execute the functions of the x-module. Other modules are implemented similarly. All or part of the modules can be integrated together or can be independently realized. The processing element described herein may be an integrated circuit having signal processing capabilities. In the implementation process, each step of the above method or each module above can be completed by the integrated logic circuit of hardware in the processor element or instructions in the form of software. These above modules may be one or more integrated circuits configured to implement the above methods, such as: one or more Application Specific Integrated Circuits (ASICs), one or more microprocessors (DSPs), one or more Field Programmable Gate Arrays (FPGAs), and the like. When a module is implemented in the form of a Processing element scheduler code, the Processing element may be a general-purpose processor, such as a Central Processing Unit (CPU) or other processor capable of calling program code. These modules may be integrated together and implemented in the form of a System-on-a-chip (SOC).
As shown in fig. 5, in an embodiment, the time-frequency interleaving method in the OFDM system of the present invention includes the following steps:
step S51 is to perform frequency interleaving on the K data sequences with length L according to the frequency interleaving method in the OFDM system.
When K is greater than 1, K data sequences of length L are first frequency interleaved. The frequency interleaving method is as described above, and therefore is not described herein again.
Preferably, when frequency interleaving is performed, the sequence of the row sequence numbers of the interleaver after sorting is not changed. In this case, the data sequence after frequency interleaving is still the original data sequence, which is equivalent to not performing frequency interleaving.
And step S52, writing the data sequence after frequency interleaving into data blocks Y of qL rows and K/Q columns according to columns, wherein Q is more than or equal to 1 and less than or equal to Q, and Q represents the symbol number of a subframe in the OFDM system.
And step S53, performing left cyclic shift on each row of the data block Y according to a preset offset to obtain a data block Z of qL rows and K/q columns.
In an embodiment of the present invention, the preset offset s ═ mod (R-1, qK), where R is a row sequence number sorted when frequency interleaving is performed according to a first preset rule or a column sequence number sorted when frequency interleaving is performed according to a second preset rule. Preferably, R is a row sequence number sorted when the frequency corresponding to the first row data of the data block Y is interleaved or a column sequence number sorted when the frequency corresponding to the first row data of the data block Y is interleaved.
Step S54, when Q/Q is equal to 1, moving the rear qL/Q row of the data block Z from the lower side to the right side, and outputting the data block W after time interleaving of L rows and K columns; and when Q/Q is smaller than 1, the data block Z is the data block W after time interleaving.
The time-frequency interleaving method in the OFDM system of the present invention is further described below by specific embodiments.
EXAMPLE III
As shown in fig. 6, the number of symbols in one subframe is set to Q2, and the number of code blocks N carried in one subframe is set to NCBThe length C of one code block is 12, and time-frequency interleaving is performed on code blocks of K6 OFDM. 1-12 code blocks of a subframe 1 in input data X are respectively mapped on a first OFDM symbol and a second OFDM symbol; code blocks 13-24 of subframe 2, respectively mapped to the thirdOne OFDM symbol and the fourth OFDM symbol, and so on. First, a 6 × 2 frequency interleaver is selected, where p is 1, and the sequence number of the sorted row is calculated as [142536 ]]And reading out every 1 column according to the new row sequence number to obtain the data vector y after frequency interleaving. When time interleaving is performed, q is 1 and q is 2, and time interleaving results W and z (W) are obtained.
Example four
As shown in fig. 7, the number of symbols in one subframe is set to Q2, and the number of code blocks N carried in one subframe is set to NCBThe length C of one code block is 6, and the data length L of one symbol is 15, and time-frequency interleaving is performed on 4 OFDM code blocks. 1 to 6, 7 to 12, 13 to 18, 19 to 24, and 25 to 30 of the input data X are respectively the 1 st to 5 th code blocks of the subframe 1, the first 2.5 code blocks, i.e., 1 to 15, are mapped on the first OFDM symbol of the subframe 1, the last 2.5 code blocks (19 to 30) are mapped on the 2 nd OFDM symbol of the subframe 1, and so on for the other subframe data. Selecting a 6 × 3 frequency interleaver to perform frequency interleaving on data on each OFDM symbol, and since 15 data on one symbol cannot be exactly filled, 3 data need to be filled before frequency interleaving, where the filling data is-1, then performing frequency interleaving on each OFDM symbol, in this embodiment, selecting p ═ 3, that is, reading out every three columns according to the sequence number of a new row until the data of all the columns are read out, and then deleting the filling units. This embodiment considers two cases, q 1 and q 2, where Y is a 15 × 4 matrix with q 1, represented by Ri,1≤i≤qMNCBCalculating to obtain a cyclic shift value siAnd further carrying out left cyclic shift on Y according to the cyclic shift value corresponding to each line to obtain a time interleaving output result Z (W). When q is 2, Y is a matrix of 30 × 2, and similarly, the matrix is cyclically shifted to obtain a data matrix Z, and in order to adapt to time-frequency resources, Z is transformed, and the lower half is shifted to the right half to obtain an output matrix W of 15 × 4.
As shown in fig. 8, in an embodiment of the invention, the time-frequency interleaving system in the OFDM system includes a frequency interleaving module 81, a writing module 82, a cyclic shift module 83 and an output module 84.
The frequency interleaving module 81 is configured to perform frequency interleaving on the K data sequences with the length of L according to the frequency interleaving method in the OFDM system.
The writing module 82 is connected to the frequency interleaving module 81, and is configured to write the data sequence after frequency interleaving into a data block Y in qL rows and K/Q columns, where Q is greater than or equal to 1 and less than or equal to Q, and Q represents a symbol number of a subframe in the OFDM system.
The cyclic shift module 83 is connected to the write module 82, and configured to perform cyclic shift on each row of the data block Y leftward according to a preset offset, so as to obtain a data block Z in qL rows and K/q columns.
The output module 84 is connected to the cyclic shift module 83, and configured to move the last qL/Q row of the data block Z from below to the right when Q/Q is equal to 1, and output the time-interleaved data block W of L rows and K columns; and when Q/Q is less than 1, the data block Z is the data block W after time interleaving.
The structures and principles of the frequency interleaving module 81, the writing module 82, the cyclic shift module 83, and the output module 74 correspond to the steps in the time-frequency interleaving method in the OFDM system one to one, and therefore are not described herein again.
It should be noted that the division of the modules of the above apparatus is only a logical division, and the actual implementation may be wholly or partially integrated into one physical entity, or may be physically separated. And the modules can be realized in a form that all software is called by the processing element, or in a form that all the modules are realized in a form that all the modules are called by the processing element, or in a form that part of the modules are called by the processing element. For example: the x module can be a separately established processing element, and can also be integrated in a certain chip of the device. In addition, the x-module may be stored in the memory of the apparatus in the form of program code, and a certain processing element of the apparatus may call and execute the functions of the x-module. Other modules are implemented similarly. All or part of the modules can be integrated together or can be independently realized. The processing element described herein may be an integrated circuit having signal processing capabilities. In the implementation process, each step of the above method or each module above can be completed by the integrated logic circuit of hardware in the processor element or instructions in the form of software. These above modules may be one or more integrated circuits configured to implement the above methods, such as: one or more Application Specific Integrated Circuits (ASICs), one or more microprocessors (DSPs), one or more Field Programmable Gate Arrays (FPGAs), and the like. When a module is implemented in the form of a Processing element scheduler code, the Processing element may be a general-purpose processor, such as a Central Processing Unit (CPU) or other processor capable of calling program code. These modules may be integrated together and implemented in the form of a System-on-a-chip (SOC).
In summary, the present invention provides a method and system for interleaving frequency and time frequency in an OFDM system. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be accomplished by those skilled in the art without departing from the spirit and scope of the present invention as set forth in the appended claims.

Claims (10)

1. A method of frequency interleaving in an OFDM system, characterized by: the method comprises the following steps:
writing data with the length of L into an interleaver with M rows and N columns according to columns or an interleaver with M columns and N rows according to rows;
when writing into an interleaver with M rows and N columns, sequencing the row sequence number of the interleaver according to a first preset rule, sequentially reading out each p columns of data according to the sequenced row sequence number R, and sequentially reading out the rest columns of data when the last rest columns are less than p columns to form frequency interleaved data, wherein p is more than or equal to 1 and less than or equal to N;
when writing into the interleaver with M columns and N rows, sequencing the column sequence numbers of the interleaver according to a second preset rule, sequentially reading each p rows of data according to the sequenced column sequence number R, and sequentially reading each remaining row of data when the last remaining row number is less than p rows to form frequency interleaved data, wherein p is more than or equal to 1 and less than or equal to N.
2. The method of claim 1, wherein the time-frequency interleaving is performed in an OFDM system, and wherein: l is integral multiple or fractional multiple of the number of code blocks in the OFDM system.
3. The method of frequency interleaving in an OFDM system according to claim 1, wherein: m ═ L, N ═ 1, and p ═ 1.
4. The method of frequency interleaving in an OFDM system according to claim 1, wherein: n ═ max { NCB,Q}，
Figure FDA0002271503470000011
1≤p≤NCBIn which N isCBDenotes the number of code blocks carried by one subframe in the OFDM system, Q denotes the number of symbols of one subframe,
Figure FDA0002271503470000012
indicating rounding up.
5. The method of frequency interleaving in an OFDM system according to claim 4, wherein:
Figure FDA0002271503470000013
6. a frequency interleaving system in an OFDM system, characterized by: the device comprises a writing module, a first processing module and a second processing module;
the writing module is used for writing data with the length of L into an interleaver with M rows and N columns according to columns or writing the data into an interleaver with M rows and N rows according to rows;
the first processing module is used for sorting the row serial numbers of the interleaver according to a first preset rule when the interleaver with M rows and N columns is written in, sequentially reading out each p columns of data according to the sorted row serial numbers R, and sequentially reading out the rest columns of data when the number of the last rest columns is less than p columns so as to form data after frequency interleaving, wherein p is more than or equal to 1 and less than or equal to N;
the second processing module is used for sorting the column sequence numbers of the interleavers according to a second preset rule when the interleavers with M columns and N rows are written in, sequentially reading every p rows of data according to the sorted column sequence numbers R, and sequentially reading the rest rows of data when the last rest row number is less than p rows to form frequency interleaved data, wherein p is more than or equal to 1 and less than or equal to N.
7. A time-frequency interleaving method in an OFDM system is characterized in that: the method comprises the following steps:
the method for frequency interleaving in an OFDM system according to any one of claims 1 to 5, wherein the method frequency interleaves K data sequences of length L;
writing the data sequence after frequency interleaving into a data block Y of qL rows and K/Q columns according to columns, wherein Q is more than or equal to 1 and less than or equal to Q, and Q represents the symbol number of a subframe in the OFDM system;
circularly shifting each row of the data block Y leftwards according to a preset offset to obtain a data block Z of qL rows and K/q columns;
when Q/Q is equal to 1, moving the rear qL/Q row of the data block Z from the lower side to the right side, and outputting a data block W formed by time interleaving of L rows and K columns; and when Q/Q is smaller than 1, the data block Z is the data block W after time interleaving.
8. The method of claim 7, wherein the time-frequency interleaving is performed in an OFDM system, and wherein: when frequency interleaving is carried out, the sequence of the row sequence numbers of the interleaver after sequencing is unchanged.
9. The method of claim 7, wherein the time-frequency interleaving is performed in an OFDM system, and wherein: and the preset offset s is mod (R-1, K/q), and R is a row sequence number sequenced when frequency interleaving is performed according to a first preset rule or a column sequence number sequenced when frequency interleaving is performed according to a second preset rule.
10. A time-frequency interleaving system in an OFDM system is characterized in that: the device comprises a frequency interleaving module, a writing module, a cyclic shift module and an output module;
the frequency interleaving module is used for frequency interleaving K data sequences with length L according to the frequency interleaving method in the OFDM system of one of claims 1-5;
the writing module is used for writing the data sequence after the frequency interleaving into a data block Y of qL rows and K/Q columns according to columns, Q is more than or equal to 1 and less than or equal to Q, and Q represents the symbol number of a subframe in the OFDM system;
the cyclic shift module is used for carrying out cyclic shift on each row of the data block Y leftwards according to a preset offset to obtain a data block Z of qL rows and K/q columns;
the output module is used for moving the rear qL/Q row of the data block Z to the right from the lower part when Q/Q is equal to 1, and outputting the data block W after time interleaving of L rows and K columns; and when Q/Q is smaller than 1, the data block Z is the data block W after time interleaving.
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