CN112804026B - Frequency and time frequency interleaving method and system in OFDM system - Google Patents

Abstract

The present invention provides a frequency and time-frequency interleaving method and system in an OFDM system, comprising the following steps: writing the data with a length of L into an interleaver with M rows and N columns by column or by writing it into an interleaver with M columns and N rows by row ; When writing into the interleaver of M rows and N columns, the row numbers of the interleaver are sorted according to the first preset rule, and then each p column of data is read in turn according to the sorted row numbers, and the last remaining column When the number is less than p columns, read out the remaining data in each column in turn to form frequency-interleaved data, where 1≤p≤N; when writing into an interleaver with M columns and N rows, the The column numbers of the interleaver are sorted, and then the data of each p row is sequentially read according to the sorted column numbers, and when the number of the last remaining rows is less than p rows, the data of each remaining row is sequentially read to form frequency interleaved data, where 1≤p≤N. The frequency and time-frequency interleaving method and system in the OFDM system of the present invention can effectively improve the interleaving performance when one symbol in the OFDM system carries non-integer code blocks.

Description

A frequency and time-frequency interleaving method and system in OFDM system

Technical Field

The present invention relates to the technical field of transmission communication, and in particular to a frequency and time-frequency interleaving method and system in an OFDM system.

Background Art

In wireless communication systems, especially wireless broadcasting systems, in order to improve the system's fault tolerance, it is necessary to achieve error-free transmission as much as possible at the receiving end. Usually, time interleaving technology is used to resist channel interference. Since the probability of errors in adjacent information units at the same time is generally high, block errors are easily formed and difficult to correct. Therefore, the task of scrambling adjacent information units as much as possible for transmission, namely time interleaving, has become an important link in solving the stability of communication systems and data accuracy.

Block interleaving changes the distribution of data under certain rules, increases the distance between adjacent original data, and reduces the probability of continuous errors. When considering writing an M*N matrix by column, the number of rows M represents the number of units in a code block, the number of columns N represents the number of code blocks, and N is greater than or equal to 1.

In an Orthogonal Frequency Division Multiplexing (OFDM) system, a subframe carries an integer number of coded code blocks. However, the number of code blocks carried by a symbol is not necessarily an integer. When an OFDM symbol can carry a non-integer number of code blocks, how to design time-frequency interleaving to effectively improve time diversity gain is a problem that needs to be solved urgently.

Summary of the invention

In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a frequency and time-frequency interleaving method and system in an OFDM system, which can effectively improve the interleaving performance when a symbol in the OFDM system carries a non-integer number of code blocks.

To achieve the above-mentioned purpose and other related purposes, the present invention provides a frequency interleaving method in an OFDM system, comprising the following steps: writing data of length L into an interleaver of M rows and N columns by column or into an interleaver of M columns and N rows by row; when writing into an interleaver of M rows and N columns, sorting the row numbers of the interleaver according to a first preset rule, and then reading out each p columns of data in sequence according to the sorted row numbers R, and when the number of remaining columns is less than p columns, reading out each remaining column of data in sequence to form frequency interleaved data, wherein 1≤p≤N; when writing into an interleaver of M columns and N rows, sorting the column numbers of the interleaver according to a second preset rule, and then reading out each p rows of data in sequence according to the sorted column numbers R, and when the number of remaining rows is less than p rows, reading out each remaining row of data in sequence to form frequency interleaved data, wherein 1≤p≤N.

In one 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.

1≤p≤N_CB，其中N_CB表示OFDM系统中一个子帧承载的码块数，Q表示一个子帧的符号数，

表示向上取整。In one embodiment of the present invention, N=max{N _CB ,Q},

1≤p≤N _CB , where N _CB represents the number of code blocks carried by a subframe in the OFDM system, Q represents the number of symbols in a subframe,

Indicates rounding up.

In one embodiment of the present invention,

Correspondingly, the present invention provides a frequency interleaving system in an OFDM system, comprising a writing module, a first processing module and a second processing module;

The writing module is used to write data of length L into an interleaver of M rows and N columns by column or into an interleaver of M columns and N rows by row;

The first processing module is used for, when writing into an interleaver of M rows and N columns, sorting the row numbers of the interleaver according to a first preset rule, and then sequentially reading out data of each p column according to the sorted row number R, and when the number of remaining columns is less than p columns, sequentially reading out the remaining data of each column to form frequency interleaved data, where 1≤p≤N;

The second processing module is used to sort the column numbers of the interleaver according to a second preset rule when writing to an interleaver of M columns and N rows, and then read out each p rows of data in sequence according to the sorted column number R, and when the number of remaining rows is less than p rows, read out each remaining row of data in sequence to form frequency interleaved data, where 1≤p≤N.

The present invention provides a time-frequency interleaving method in an OFDM system, comprising the following steps:

Perform frequency interleaving on K data sequences of length L according to the frequency interleaving method in the OFDM system described above;

The frequency interleaved data sequence is written into a data block Y with qL rows and K/q columns, 1≤q≤Q, where Q represents the number of symbols in a subframe in the OFDM system;

Circularly shift each row of the data block Y to the left according to a preset offset to obtain a data block Z with qL rows and K/q columns;

When q/Q is equal to 1, the last qL/Q rows of the data block Z are moved from the bottom to the right, and the data block W after time interleaving of L rows and K columns is output; when q/Q is less than 1, the data block Z is the data block W after time interleaving.

In one embodiment of the present invention, when frequency interleaving is performed, the order of the row numbers of the interleaver remains unchanged.

In one embodiment of the present invention, the preset offset s=mod(R-1,K/q), where R is the row number after sorting when frequency interleaving is performed according to the first preset rule or the column number after sorting when frequency interleaving is performed according to the second preset rule.

Correspondingly, the present invention provides a time-frequency interleaving system in an OFDM system, comprising a frequency interleaving module, a writing module, a cyclic shift module and an output module;

The frequency interleaving module is used to perform frequency interleaving on K data sequences of length L according to the frequency interleaving method in the OFDM system mentioned above;

The writing module is used to write the frequency interleaved data sequence into a data block Y with qL rows and K/q columns, 1≤q≤Q, where Q represents the number of symbols in a subframe in the OFDM system;

The cyclic shift module is used to cyclically shift each row of the data block Y to the left according to a preset offset to obtain a data block Z with qL rows and K/q columns;

The output module is used to move the last qL/Q rows of the data block Z from the bottom to the right when q/Q is equal to 1, and output the data block W after time interleaving of L rows and K columns; when q/Q is less than 1, the data block Z is the data block W after 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 beneficial effects:

(1) It supports not only time-frequency interleaving when an OFDM symbol carries integer multiple code blocks, but also time-frequency interleaving when an OFDM symbol carries fractional multiple code blocks;

(2) Providing a variety of time-frequency interleaving modes with different configurations, with strong flexibility and scenario adaptability;

(3) Effectively improves the time-frequency interleaving performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a flow chart showing a time interleaving method in an OFDM system according to an embodiment of the present invention;

FIG2 is a schematic diagram showing a time interleaving method in an OFDM system according to a first embodiment of the present invention;

FIG3 is a schematic diagram showing a time interleaving method in an OFDM system according to a second embodiment of the present invention;

FIG4 is a schematic diagram showing the structure of a time interleaving system in an OFDM system according to an embodiment of the present invention;

FIG5 is a flow chart showing a method for time-frequency interleaving in an OFDM system according to an embodiment of the present invention;

FIG6 is a schematic diagram showing a time-frequency interleaving method in an OFDM system according to a first embodiment of the present invention;

FIG7 is a schematic diagram showing a time-frequency interleaving method in an OFDM system according to a second embodiment of the present invention;

FIG8 is a schematic diagram showing the structure of a time-frequency interleaving system in an OFDM system according to an embodiment of the present invention;

DETAILED DESCRIPTION

The following is an explanation of the embodiments of the present invention by specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

The frequency and time-frequency interleaving method and system in the OFDM system of the present invention are compatible with the time interleaving and time-frequency interleaving of an OFDM symbol carrying integer or fractional multiple code blocks, and effectively improve the interleaving performance and have strong practicality.

As shown in FIG. 1 , in one embodiment, the frequency interleaving method in an OFDM system of the present invention comprises the following steps:

Step S11, write data of length L into an interleaver of M rows and N columns by column or write data into an interleaver of M columns and N rows by row.

In one embodiment, for a data sequence x{x ₁ , . . . , x _L } of length L, it is sequentially written into an interleaver with M rows and N columns.

In another embodiment, for a data sequence x{x ₁ , . . . , x _L } of length L, the data sequence is sequentially written into an interleaver with M columns and N rows.

In one embodiment of the present invention, L is an integer multiple or fractional multiple of the number of code blocks in the OFDM system, so that it is compatible with the situation where one OFDM symbol carries an integer multiple or fractional multiple of code blocks.

Assuming the length of a code block to be C, then L=CN _CB /Q, N _CB represents the number of code blocks carried by a subframe in the OFDM system, and Q represents the number of symbols in a subframe.

Step S12, when writing an interleaver with M rows and N columns, sort the row numbers of the interleaver according to the first preset rule, and then read out each p column data in turn according to the sorted row number R, and when the number of remaining columns is less than p columns, read out each remaining column data in turn to form frequency interleaved data, where 1≤p≤N.

Specifically, the first preset rule can be expressed by the following formula:

表示预设间隔； M≥i≥2，R₁＝1，

表示向上取整，

表示向下取整。当写入数据长度不是正好是M的 倍数时，即N为分数时，在输入数据末尾补填

个填充数据再写入所述交织器， 并在读出数据时跳过所述填充数据。Among them, _Ri represents the row number at the i-th position after sorting;

Indicates the preset interval; M≥i≥2, R ₁ ＝1,

Indicates rounding up.

Indicates rounding down. When the length of the written data is not exactly a multiple of M, that is, when N is a fraction, fill in the end of the input data

The padding data is then written into the interleaver and the padding data is skipped when the data is read out.

Specifically, the first preset rule can also be expressed by R _i =i.

In an embodiment of the present invention, M=L, N=1, and p=1. This indicates that frequency interleaving is performed on data by symbol.

1≤p≤N_CB，其中N_CB表示OFDM系统中一个子帧承载的码块数，Q表示一个子帧的符号数，

表示向上取整。此时 表示按码块对数据进行频率交织。通常，Q数取值1或2。优选地，

In another embodiment of the present invention, N=max{N _CB ,Q},

1≤p≤N _CB , where N _CB represents the number of code blocks carried by a subframe in the OFDM system, Q represents the number of symbols in a subframe,

Indicates rounding up. This indicates frequency interleaving of data by code block. Usually, the Q number takes a value of 1 or 2. Preferably,

Specifically, when reading out data, p columns of data are used as units and read out in sequence. The remaining data less than p columns are still read out in sequence to obtain frequency interleaved data.

Step S13, when writing an interleaver of M columns and N rows, sort the column numbers of the interleaver according to the second preset rule, and then read out each p rows of data in sequence according to the sorted column number R, and when the number of remaining rows is less than p rows, read out each remaining row of data in sequence to form frequency interleaved data, where 1≤p≤N.

Specifically, the second preset rule can be expressed by the following formula:

表示预设间隔； M≥i≥2，R₁＝1，

表示向上取整，

表示向下取整。当写入数据长度不是正好是M的 倍数时，即N为分数时，在输入数据末尾补填

个填充数据再写入所述交织器， 并在读出数据时跳过所述填充数据。Among them, _Ri represents the column number at the i-th position after sorting;

Indicates the preset interval; M≥i≥2, R ₁ ＝1,

Indicates rounding up.

Indicates rounding down. When the length of the written data is not exactly a multiple of M, that is, when N is a fraction, fill in the end of the input data

The padding data is then written into the interleaver and the padding data is skipped when the data is read out.

Specifically, the second preset rule can also be expressed by R _i =i.

In an embodiment of the present invention, M=L, N=1, and p=1. This indicates that frequency interleaving is performed on data by symbol.

1≤p≤N_CB，其中N_CB表示OFDM系统中一个子帧承载的码块数，Q表示一个子帧的符号数，

表示向上取整。此时 表示按码块对数据进行频率交织。通常，Q数取值1或2。优选地，

In another embodiment of the present invention, N=max{N _CB ,Q},

1≤p≤N _CB , where N _CB represents the number of code blocks carried by a subframe in the OFDM system, Q represents the number of symbols in a subframe,

Indicates rounding up. This indicates frequency interleaving of data by code block. Usually, the Q number takes a value of 1 or 2. Preferably,

Specifically, when reading out data, p rows of data are used as units and the data is read out in sequence. The remaining data less than p rows are still read out in sequence to obtain frequency interleaved data.

The frequency interleaving method in an OFDM system of the present invention is further described below through specific embodiments.

Set the number of subframes K of the data X to be interleaved to 1, the number of symbols Q in a subframe to 1, and only frequency interleaving is performed. Set the number of code blocks carried by a subframe to N _CB to 3, the length of a code block to C to 7, and the length of the encoded data carried by a symbol to L to 21. Among them, 1 to 7 belong to the first code block of the subframe (or symbol), 8 to 14 belong to its second code block, and 15 to 21 belong to the third code block.

Embodiment 1

The number of rows of the frequency interleaver is M=L=21, N=1, and p=1. After the row numbers are sorted, the data results before and after the frequency interleaving are obtained according to the new row numbers, as shown in FIG2.

Embodiment 2

Assuming the number of rows of the frequency interleaver is M=C=7, N= _NCB =3, and p=3, the data results before and after frequency interleaving are shown in FIG3 .

As shown in FIG. 4 , in one 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 used to write data of length L into an interleaver of M rows and N columns by column or into an interleaver of M columns and N rows by row.

The first processing module 42 is connected to the writing module 41, and is used to sort the row numbers of the interleaver according to a first preset rule when writing to an interleaver of M rows and N columns, and then read out each p columns of data in sequence according to the sorted row number R, and when the number of remaining columns is less than p columns, read out each remaining column of data in sequence to form frequency interleaved data, where 1≤p≤N.

The second processing module 43 is connected to the writing module 41, and is used to sort the column numbers of the interleaver according to the second preset rule when writing to the interleaver of M columns and N rows, and then read out each p rows of data in sequence according to the sorted column number R, and when the number of remaining rows is less than p rows, read out each remaining row of data in sequence to form frequency interleaved data, where 1≤p≤N.

Among them, the structures and principles of the writing module 41, the first processing module 42 and the second processing module 43 correspond one to one with the steps in the frequency interleaving method in the above-mentioned OFDM system, so they are not repeated here.

It should be noted that it should be understood that the division of the modules of the above device is only a division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or physically separated. And these modules can all be implemented in the form of software called by processing elements, or all in the form of hardware, or some modules can be implemented in the form of software called by processing elements, and some modules can be implemented in the form of hardware. For example: the x module can be a separate processing element, or it can be integrated in a chip of the above device. In addition, the x module can also be stored in the memory of the above device in the form of program code, and called and executed by a processing element of the above device. The implementation of other modules is similar. These modules can be fully or partially integrated together, or they can be implemented independently. The processing element described here can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each module above can be completed by an integrated logic circuit of hardware in a processor element or an instruction in the form of software. The 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 digital singnal processors (DSPs), one or more field programmable gate arrays (FPGAs), etc. When a module is implemented in the form of a processing element scheduling program code, the processing element may be a general-purpose processor, such as a central processing unit (CPU) or other processors that can call program code. These modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).

As shown in FIG5 , in one embodiment, the time-frequency interleaving method in an OFDM system of the present invention comprises the following steps:

Step S51: frequency interleave K data sequences of length L according to the frequency interleaving method in the OFDM system described above.

When K is greater than 1, frequency interleaving is first performed on K data sequences of length L. The frequency interleaving method is as described above, so it will not be repeated here.

Preferably, when frequency interleaving is performed, the order of the row numbers of the interleaver remains unchanged. At this time, the data sequence after frequency interleaving is still the original data sequence, which is equivalent to not performing frequency interleaving.

Step S52, write the frequency interleaved data sequence into a data block Y with qL rows and K/q columns, 1≤q≤Q, and Q represents the number of symbols in a subframe in the OFDM system.

Step S53: cyclically shift each row of the data block Y to the left according to a preset offset to obtain a data block Z with qL rows and K/q columns.

In one embodiment of the present invention, the preset offset s=mod(R-1,qK), R is the row number after frequency interleaving is performed according to the first preset rule or the column number after frequency interleaving is performed according to the second preset rule. Preferably, R is the row number after frequency interleaving corresponding to the first column of data of the data block Y or the column number after frequency interleaving corresponding to the first row of data of the data block Y.

Step S54, when q/Q is equal to 1, the last qL/Q rows of the data block Z are moved from the bottom to the right, and the data block W after time interleaving of L rows and K columns is output; when q/Q is less than 1, the data block Z is the data block W after time interleaving.

The time-frequency interleaving method in an OFDM system of the present invention is further described below through specific embodiments.

Embodiment 3

As shown in Figure 6, the number of symbols in a subframe is set to Q = 2, the number of code blocks carried by a subframe is N _CB = 1, the length of a code block is C = 12, and K = 6 OFDM code blocks are time-frequency interleaved. In the input data X, 1 to 12 are code blocks of subframe 1, which are mapped to the first OFDM symbol and the second OFDM symbol respectively; 13 to 24 are code blocks of subframe 2, which are mapped to the third OFDM symbol and the fourth OFDM symbol respectively, and so on. First, select a 6×2 frequency interleaver, p = 1, calculate the sorted row number to be [142536], and read out each column according to the new row number to obtain the frequency interleaved data vector y. When time interleaving, take q = 1 and q = 2 to obtain the time interleaving results W and Z(W) respectively.

Embodiment 4

As shown in FIG7 , the number of symbols in a subframe is set to Q=2, the number of code blocks carried by a subframe is N _CB =5, the length of a code block is C=6, the data length on a symbol is L=15, and the K=4 OFDM code blocks are time-frequency interleaved. 1-6, 7-12, 13-18, 19-24, 25-30 in the input data X are the 1st to 5th code blocks of subframe 1 respectively, the first 2.5 code blocks, i.e., 1-15, are mapped to the first OFDM symbol of subframe 1, and the last 2.5 code blocks (19-30) are mapped to the second OFDM symbol of subframe 1, and the data of another subframe is deduced in the same way. A 6×3 frequency interleaver is selected to perform frequency interleaving on the data on each OFDM symbol. Since the 15 data on a symbol cannot be exactly filled, 3 data need to be filled before frequency interleaving. Here, the filling data is set to -1, and then frequency interleaving is performed on each OFDM. In this embodiment, p=3 is selected, that is, every three columns are read out according to the sequence number of the new row until the data of all columns are read out, and then the filling unit is deleted. This embodiment considers two cases of q=1 and q=2. When q=1, Y is a 15×4 matrix. The cyclic shift value s _i is calculated by R _i ,1≤i≤qMN _CB /Q, and then Y is cyclically shifted to the left according to the cyclic shift value corresponding to each row to obtain the time interleaved output result Z (W). When q=2, Y is a 30×2 matrix. Similarly, it is cyclically shifted to obtain the data matrix Z. In order to adapt to the time-frequency resources, Z is deformed, and the lower half is moved to the right half to obtain a 15×4 output matrix W.

As shown in FIG. 8 , in one embodiment, the time-frequency interleaving system in the OFDM system of the present invention 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 used to perform frequency interleaving on K data sequences of length L according to the frequency interleaving method in the above-mentioned OFDM system.

The writing module 82 is connected to the frequency interleaving module 81, and is used to write the frequency interleaved data sequence into a data block Y of qL rows and K/q columns, 1≤q≤Q, and Q represents the number of symbols in a subframe in the OFDM system.

The cyclic shift module 83 is connected to the writing module 82, and is used to cyclically shift each row of the data block Y to the left according to a preset offset to obtain a data block Z with qL rows and K/q columns.

The output module 84 is connected to the cyclic shift module 83, and is used to move the last qL/Q rows of the data block Z from the bottom to the right when q/Q is equal to 1, and output the data block W after time interleaving of L rows and K columns; when q/Q is less than 1, the data block Z is the data block W after time interleaving.

Among them, 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 one by one to the steps in the time-frequency interleaving method in the above-mentioned OFDM system, so they are not repeated here.

It should be noted that it should be understood that the division of the modules of the above device is only a division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or physically separated. And these modules can all be implemented in the form of software called by processing elements, or all in the form of hardware, or some modules can be implemented in the form of software called by processing elements, and some modules can be implemented in the form of hardware. For example: the x module can be a separate processing element, or it can be integrated in a chip of the above device. In addition, the x module can also be stored in the memory of the above device in the form of program code, and called and executed by a processing element of the above device. The implementation of other modules is similar. These modules can be fully or partially integrated together, or they can be implemented independently. The processing element described here can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each module above can be completed by an integrated logic circuit of hardware in a processor element or an instruction in the form of software. The 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 digital singnal processors (DSPs), one or more field programmable gate arrays (FPGAs), etc. When a module is implemented in the form of a processing element scheduling program code, the processing element may be a general-purpose processor, such as a central processing unit (CPU) or other processors that can call program code. These modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).

In summary, the frequency and time-frequency interleaving method and system in the OFDM system of the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Any person familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims (9)

1. A frequency interleaving method in an OFDM system, characterized in that it comprises the following steps: Write the data of length L into an interleaver of M rows and N columns by column or into an interleaver of M columns and N rows by row; When writing to an interleaver with M rows and N columns, the row numbers of the interleaver are sorted according to a first preset rule, and then the data of each p columns are read out in sequence according to the sorted row numbers R, and when p is greater than 1 and the number of remaining columns is less than p columns, the remaining data of each column is read out in sequence to form frequency interleaved data, where 1≤p≤N; When writing to an interleaver with M columns and N rows, the column numbers of the interleaver are sorted according to a second preset rule, and then each p rows of data are read out in sequence according to the sorted column numbers R, and when p is greater than 1 and the number of remaining rows is less than p rows, each remaining row of data is read out in sequence to form frequency interleaved data, where 1≤p≤N; N＝max{N _CB ,Q}，

1≤p≤N _CB , where N _CB represents the number of code blocks carried by a subframe in the OFDM system, Q represents the number of symbols in a subframe,

Indicates rounding up. 2. The frequency interleaving method in an OFDM system according to claim 1 is characterized in that: L is an integer multiple or fractional multiple of the number of code blocks in the OFDM system. 3. The frequency interleaving method in an OFDM system according to claim 1 is characterized in that: M=L, N=1, p=1. 4. The frequency interleaving method in an OFDM system according to claim 1, characterized in that:

5. A frequency interleaving system in an OFDM system, characterized by comprising a writing module, a first processing module and a second processing module; The writing module is used to write data of length L into an interleaver of M rows and N columns by column or into an interleaver of M columns and N rows by row; The first processing module is used for, when writing to an interleaver with M rows and N columns, sorting the row numbers of the interleaver according to a first preset rule, and then reading out each p column data in sequence according to the sorted row number R, and when p is greater than 1 and the number of remaining columns is less than p columns, reading out each remaining column data in sequence to form frequency interleaved data, wherein 1≤p≤N; the second processing module is used for, when writing to an interleaver with M columns and N rows, sorting the column numbers of the interleaver according to a second preset rule, and then reading out each p row data in sequence according to the sorted column number R, and when p is greater than 1 and the number of remaining rows is less than p rows, reading out each remaining row data in sequence to form frequency interleaved data, wherein 1≤p≤N; N＝max{N _CB ,Q},

1≤p≤N _CB , where N _CB represents the number of code blocks carried by a subframe in the OFDM system, Q represents the number of symbols in a subframe,

Indicates rounding up. 6. A time-frequency interleaving method in an OFDM system, characterized in that it comprises the following steps: The frequency interleaving method in an OFDM system according to any one of claims 1 to 4 performs frequency interleaving on K data sequences of length L; The frequency interleaved data sequence is written into a data block Y with qL rows and K/q columns, 1≤q≤Q, where Q represents the number of symbols in a subframe in the OFDM system; Circularly shift each row of the data block Y to the left according to a preset offset to obtain a data block Z with qL rows and K/q columns; When q/Q is equal to 1, the last qL/Q rows of the data block Z are moved from the bottom to the right, and the data block W after time interleaving of L rows and K columns is output; when q/Q is less than 1, the data block Z is the data block W after time interleaving. 7. The time-frequency interleaving method in an OFDM system according to claim 6 is characterized in that when frequency interleaving is performed, the order of the row numbers of the interleaver remains unchanged. 8. The time-frequency interleaving method in an OFDM system according to claim 6 is characterized in that: the preset offset s = mod(R-1, K/q), R is the row number after sorting when frequency interleaving is performed according to the first preset rule or the column number after sorting when frequency interleaving is performed according to the second preset rule. 9. A time-frequency interleaving system in an OFDM system, characterized by comprising a frequency interleaving module, a writing module, a cyclic shift module and an output module; The frequency interleaving module is used to perform frequency interleaving on K data sequences of length L by the frequency interleaving method in an OFDM system according to any one of claims 1 to 4; The writing module is used to write the frequency interleaved data sequence into a data block Y of qL rows and K/q columns, 1≤q≤Q, and Q represents the number of symbols in a subframe in the OFDM system; The cyclic shift module is used to cyclically shift each row of the data block Y to the left according to a preset offset to obtain a data block Z with qL rows and K/q columns; The output module is used to move the last qL/Q rows of the data block Z from the bottom to the right when q/Q is equal to 1, and output the data block W after time interleaving of L rows and K columns; when q/Q is less than 1, the data block Z is the data block W after time interleaving.

Images