KR100836625B1 - Apparatus and method for discrete fourier transform - Google Patents

Abstract

A DFT(double Fourier Transform) device and a method thereof are provided to realize a DFT operation through hardware in a field needing DFT for data not a multiplier of two, reduce a memory by reading data from a buffer and storing the data to the buffer, and reduce latency and increase throughout by reducing an interval between input and output for the DFT. A buffer(200) stores data and a single stage unit(300) generates FT data by performing the FT for the data stored in the buffer. An entire stage controller(100) enables the buffer to store the data, forms a plurality of single stages respectively corresponding to a plurality of even numbers factorizing a resource unit of the data, and controls the FT by using the single stage unit for a plurality of single stage. The entire stage controller is equipped with an even number former(101) including entire stage structure information including the number and the order of single stages corresponding to a plurality of even numbers, and the even number of each single stage, and controls the single stage according to the entire stage structure information for the data stored in the even number former.

Description

Discrete Fourier Transform Apparatus and Method {APPARATUS AND METHOD FOR DISCRETE FOURIER TRANSFORM}

1 is a diagram illustrating a discrete Fourier transform device according to an embodiment of the present invention.

2 is a diagram illustrating a single stage in accordance with an embodiment of the present invention.

3 is a flowchart of a discrete Fourier transform method according to an embodiment of the present invention.

4 is a table illustrating a data structure according to an embodiment of the present invention.

5 is a table illustrating a data structure according to an embodiment of the present invention.

6 is a flowchart illustrating a sequence of Fourier transforming data by a single stage according to an exemplary embodiment of the present invention.

7 is a diagram illustrating a control parameter according to an embodiment of the present invention.

The present invention relates to a discrete Fourier transform apparatus and method. In particular, the present invention relates to an apparatus and method for implementing discrete Fourier transforms on data numbers in hardware.

The mobile communication system calculates samples using a Discrete Fourier Transform (DFT), which uses samples of time functions to numerically compute the Fourier transform. This DFT is also used to calculate the Fourier series coefficients of the energy signal. An example of the use of such a DFT is a 3rd generation long-term evolution (3G LTE) mobile communication system.

Looking at a modulator of a single carrier frequency division multiple access (SC-FDMA) method in a communication modem of a 3G LTE mobile communication system, a modulator receives data in the form of a bit stream and converts it into symbols according to the modulation type of the modulator. The modulator then performs a DFT on the symbol to convert the symbol into a signal in a frequency domain. Subsequently, the modulator performs subcarrier mapping to the signals in the frequency domain so that the modulators are continuously assigned to a frequency of a predetermined region or have a predetermined interval in the frequency domain. The modulator then performs an Inverse Fast Fourier Transform (IFFT) on the subcarrier mapped signal to output an IFFT signal.

In this case, the modulator may include a non-multiplier of 2 in the process of performing the DFT process. After the subcarrier mapping process, only data corresponding to the multiplier of 2 undergoes the IFFT process. In contrast to the modulation process of the modulator, only the data corresponding to the multiplier of 2 goes through the Fast Fourier Transform (FFT), and after the subcarrier de-mapping process, the data not the multiplier of 2 is discrete. Fourier inverse transform (Inverse DFT, IDFT).

As described above, the FFT or IFFT is only applicable to numbers with bases of 2, so it is not applicable to data consisting of bases other than 2.

An object of the present invention is to provide a method for performing Discrete Fourier Transform (DFT) on data consisting of radix other than two.

A discrete Fourier transform apparatus for receiving data having a resource unit factored into an odd number rather than a power of 2 according to an embodiment of the present invention and outputting Fourier transform data includes a buffer, a single stage unit, and an entire stage controller. The buffer stores data, and the single stage unit performs Fourier transform on the data stored in the buffer to generate Fourier transform data. The entire stage control unit controls the data to be stored in the buffer, and the resource unit of the data is stored in a plurality of radiated factors. Each of which constitutes a plurality of single stages corresponding to each other, and controls a Fourier transform using a single stage portion for each of the plurality of single stages.

In this case, the whole stage control unit includes a cardinal construction unit having total stage structure information including the number of single stages corresponding to the plurality of bases, the order of a single stage, and the base number of each single stage, Control a single stage based on overall stage structure information.

In addition, the entire stage controller controls the single stage unit to operate as many as a single stage in the order of the single stage.

In addition, the single stage unit may include a single stage controller, a Fourier transform unit, and a multiplier. The single stage controller receives the stage of the single stage to be performed by the single stage unit from the whole stage controller, controls the single stage unit based on the radix of the single stage, and the Fourier transform unit performs a single stage of data in the buffer under the control of the single stage controller. Divide into a plurality of subgroups corresponding to the radix of, and perform Fourier transform for each of the plurality of subgroups to generate a plurality of tweet factors corresponding to the plurality of subgroups, and the multiplier multiplies the plurality of tweet factors to multiply the Fourier transform data. Create

In addition, the single stage unit reads the data stored in the buffer for each stage in accordance with the order of the stages, generates Fourier transform data, stores the Fourier transform data in the buffer, and then performs the Fourier generated in the final stage according to the order of the stages. Output the converted data to the outside.

In addition, the single stage unit converts the data into Fourier transform data and stores the Fourier transform data at an address where the data is stored.

In addition, the stage controller controls the buffer to store the data in a position where the data read by the single stage unit is stored after the single stage unit reads the data stored in the buffer in the final stage.

According to another embodiment of the present invention, a method of outputting Fourier transform data by receiving data having a resource unit factored into an odd number rather than a power of 2 includes storing data and a plurality of factorized resource units of the data. Configuring an entire stage consisting of a plurality of single stages each corresponding to a plurality of radixes based on the number of single stages corresponding to the radix, the order of a single stage, and the radix of the plurality of single stages, Performing each of the plurality of single stages in the order of a single stage based on the radix of the plurality of single stages respectively corresponding to the plurality of single stages, converting the data into Fourier transform data, and outputting the converted data; .

In this case, each single stage sets the radix of a single stage corresponding to each single stage, divides data into a plurality of subgroups corresponding to the radix of a single stage, Fourier transforms each of the plurality of subgroups, and Fourier transforms. Generating a plurality of tweet factors by applying a scaling factor to the plurality of subgroups, performing a multiplication operation on the plurality of tweet factors, generating Fourier transform data, and storing Fourier transform data. Include.

In this case, the step of storing the Fourier transform data outputs the Fourier transform data if the single stage is the final stage in the order of the single stage.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise.

A discrete Fourier transform apparatus and method according to an embodiment of the present invention will now be described in detail with reference to the drawings.

Next, a discrete Fourier transform apparatus according to an embodiment of the present invention will be described with reference to FIG. 1 or FIG. 2.

1 is a diagram illustrating a discrete Fourier transform device according to an embodiment of the present invention.

As shown in FIG. 1, the discrete Fourier transform apparatus includes an entire stage controller 100, a buffer 200, and a single stage unit 300.

The entire stage controller 100 controls the buffer 200 through a memory control signal when data (Input) is input to the discrete Fourier transform device, and controls the single stage unit 300 according to the overall stage structure information of the data (Input). To control. In this case, the entire stage control unit 100 may include a cardinal construction unit having overall stage structure information of the data Input.

The buffer 200 receives and stores data Input according to the memory control signals of the entire stage controller 100.

The single stage unit 300 reads data Input from the buffer 200 under the control of the entire stage control unit 100, and performs Fourier transform on the read data Input.

2 is a diagram illustrating a single stage unit 300 according to an embodiment of the present invention.

As shown in FIG. 2, the single stage unit 300 includes a single stage controller 301, a Fourier transform unit 303, and a multiplier 305.

The single stage controller 301 controls the single stage 300 according to the control of the entire stage controller 100, and generates an address of data read by the single stage 300 from the buffer 200.

The Fourier transform unit 303 divides the data into subgroups corresponding to the radix of each single stage under the control of the single stage controller 301, and stores the data of each subgroup (hereinafter referred to as a 'base factor') in the buffer 200. After reading from, perform Fourier transform for each basic factor to generate Fourier transformed basic factor. In addition, the Fourier transform unit 303 generates a tweed factor based on the Fourier transformed basic factor.

The multiplier 305 receives a tweed factor and a Fourier transform basic factor from the Fourier transform unit 303 and performs a multiplication operation by multiplying them, and generates the multiplied data by the single stage controller 301. Stored in the buffer 200 again according to the address (address).

Next, a discrete Fourier transform method according to an embodiment of the present invention will be described with reference to FIGS. 3 to 7.

3 is a flowchart of a discrete Fourier transform method according to an embodiment of the present invention.

When external data (Input) is input to the discrete Fourier transform apparatus, first, the entire stage control unit 100 receives data (S110), and transmits a memory control signal to the buffer 200 so that the buffer 200 receives data. To store (S130).

When the data Input is stored in the next buffer 200, the entire stage control unit 100 configures the entire stage for the input data (S150). At this time, the cardinal construction unit 101 of the entire stage control unit 100 may generate overall stage structure information on the data Input, and the entire stage control unit 100 may configure a stage according to the entire stage structure information.

Hereinafter, the entire stage structure information will be described with reference to FIG. 4 or FIG. 5.

When the data number N of the data Inputs input to the discrete Fourier transform device is not fixed and changes, a predetermined reference table is required. For example, in the 3rd generation LTE mobile communication system, a basic resource unit is determined, and the number of data to be converted at once is determined by a multiple of the basic resource unit. If the basic resource unit is 25 (5 × 5), the total number of data, the number of single stages, and the radix of each single stage may be represented as shown in FIG. 4, and the basic resource unit is 12 (2 × 2 × 3). ), The number of data, the number of single stages, and the radix of each single stage can be expressed as shown in FIG. 5.

According to FIG. 4 or 5, the total stage structure information includes the number of single stages corresponding to the data number N of the input data, the order of the single stages, and the radix of each single stage. In FIG. 4 and FIG. 5, up to the case where the data number N is 1200 is displayed, and only when the radix is 2, 3, 4, and 5, the same method may be used.

Referring to FIG. 3 again, a discrete Fourier transform method according to an embodiment of the present invention will be described.

Next, the entire stage control unit 100 controls the single stage unit 300 according to the entire stage structure information, and the single stage unit 300 performs Fourier transform of data Input under the control of the entire stage control unit 100. Fourier transform data output is generated (S170).

At this time, the entire stage control unit 100 controls the single stage unit 300 to operate as many as the number of single stages of the entire stage structure information, and for each single stage, the single stage unit 300 controls data according to the radix of each single stage. Fourier transform. If N data consists of four single stages and the radix of each single stage is r1, r2, r3, r4 in order, the single stage unit 300 divides N data into r1 groups in the first single stage. In the second single stage, each group divided by the first single stage is divided into r2 subgroups. In the third single stage, each of the r1 × r2 groups calculated in the second single stage is divided into r3 subgroups. The final fourth single stage is calculated by dividing each of the r1 × r2 × r3 groups into r4 subgroups. The same process goes for the number of data having any single stage.

Hereinafter, a process of Fourier transforming data by a single stage unit with reference to FIG. 6 or 7 will be described.

6 is a flowchart illustrating a procedure of Fourier transforming data by a single stage unit according to an exemplary embodiment of the present invention.

First, the single stage controller 301 receives the radix of the current single stage from the entire stage control unit 100, and sets the radix of the current single stage by transmitting the radix of the current single stage to the Fourier transform unit 303 (S171). .

Next, the Fourier transform unit 303 divides the data stored in the buffer 200 into subgroups equal to the radix of the current single stage, reads data of one subgroup of the subgroups, and then performs Fourier transform on each data of the subgroup ( S173). The Fourier transform unit 303 repeats step S173 to perform Fourier transform on all data. In this case, the Fourier transform performed by the Fourier transform unit 303 follows Equation 1.

In Equation 1, x (n) represents N pieces of data in chronological order.

In this case, the single stage controller 301 may generate an address of the data when the Fourier transform unit 303 reads data from the buffer 200.

In this case, the address generated by the single stage controller 301 in each single stage follows the control parameter shown in FIG. 7. In other words, if the data having N number of data is composed of four single stages and the radix of each single stage is r1, r2, r3, r4 in order, the address of the first data of each subgroup in the first single stage is 0, N / r1,... , (r1-1) N / r1. And the address of the second data of each subgroup is 1, N / r1 + 1,… which increases the address of the first data by one. , (r1-1) N / r1 + 1. As such, the single stage controller 301 generates an address of the data for the entire data. In the second single stage, the address of the first data of each subgroup is 0, N / (r1 × r2),… according to the read address step. , (r2-1) N / (r1 × r2), and the address of the second data of each subgroup is increased by 1 to the address of the first data like the first single stage. The same applies to subsequent single stages.

Thereafter, the single stage controller 301 and the Fourier transform unit 303 interwork to generate a tweed factor by multiplying the Fourier transformed basic factor by the scaling factor (S175). The scaling factor in each single stage then follows FIG.

Next, the multiplier 305 generates a Fourier transform data by performing a multiplication operation on the tweed factor and the Fourier transformed basic factor (S177), and stores the Fourier transform data in the buffer (S179). In this case, the multiplier 305 may store the Fourier transform data in the buffer 200 according to the address of the data generated by the single stage controller 301, and store the Fourier transform data in the address of the data read by the Fourier transform unit 303. You can also store Fourier transform data again.

Referring to FIG. 3 again, a discrete Fourier transform method according to an embodiment of the present invention will be described.

When the calculation for one single stage is completed, the next single stage is processed under the control of the entire stage controller 100.

When the next single stage is reached, the multiplier 305 of the single stage unit 300 skips storing the Fourier transform data in the buffer 200 (S179) and outputs the Fourier transform data to the outside (S190). In this case, the Fourier transform data output by the multiplier 305 of the final stage is output data Output of which the Fourier transform is completed.

In this case, since the Fourier transform unit 303 of the single stage unit 300 reads sequentially from the buffer 200 in units of subgroups of data in the final single stage, the buffer 200 is the first Fourier transform unit 303 first. After reading the subgroup, you can write new external data in place of the first subgroup. In this case, the time taken for the data to be input from the outside and the input data is converted and output can be shortened by the time that one single stage proceeds.

The embodiments of the present invention described above are not implemented only through the apparatus and the method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded. Implementation may be easily implemented by those skilled in the art from the description of the above-described embodiments.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

According to an embodiment of the present invention, DFT calculation through hardware is possible in a field requiring DFT conversion on data that is not a multiplier of two.

In addition, according to an embodiment of the present invention, the memory can be reduced by reading the data from the buffer and storing the data in the buffer again, and the external data input interval is reduced because the new data can be input immediately after the final stage starts. As the parallax between the input and the output for the DFT operation is reduced, the latency is reduced and the throughput is increased.

Claims (10)

An apparatus for receiving data having a resource unit factored by a radix not a power of 2 and outputting Fourier transform data, A buffer for storing the data; A single stage unit generating Fourier transform data by Fourier transforming the data stored in the buffer; And Control the data to be stored in the buffer, construct a plurality of single stages each corresponding to a plurality of radiated factors whose resource units of the data, and perform Fourier transform using the single stage unit for each of the plurality of single stages Apparatus comprising a full stage control unit for controlling the. The method of claim 1, The entire stage control unit A whole stage for the data stored in said cardinal constituent, comprising an odd constituent having total stage structure information including the number of single stages corresponding to the plurality of riders, the order of a single stage, and the odd of each single stage; And control said single stage in accordance with structural information. The method of claim 2, And the entire stage control unit controls the single stage unit to operate as many as the single stage in the order of the single stage. The method of claim 3, The single stage unit A single stage controller which receives the radix of a single stage to be performed by the single stage unit from the entire stage controller, and controls the single stage unit based on the radix of the single stage; According to the control of the single stage controller, the data of the buffer is divided into a plurality of subgroups corresponding to the radix of the single stage, Fourier transform is performed for the plurality of subgroups, and a plurality of Fourier transforms respectively corresponding to the plurality of subgroups. A Fourier transform unit for generating a plurality of subgroups and generating a plurality of tweet factors respectively corresponding to the plurality of Fourier transformed subgroups based on the plurality of Fourier transformed subgroups; And And a multiplier for generating Fourier transform data by multiplying the plurality of Fourier transformed subgroups and the plurality of tweet factors. The method of claim 4, wherein The single stage unit reads data stored in the buffer for each stage in accordance with the order of the stages, and performs Fourier transform to generate Fourier transform data, and then stores Fourier transform data in the buffer. Device for outputting the generated Fourier transform data. The method of claim 5, And the single stage unit converts the data into the Fourier transform data and stores the Fourier transform data at an address where the data is stored. The method of claim 5, And the entire stage control unit controls the buffer to store data in a position where the data read by the single stage unit is stored after the single stage unit reads the data stored in the buffer in the final stage. In the method for receiving data having a resource unit factored by a radix not a power of 2 and outputting Fourier transform data, Storing the data; A plurality of single stages each corresponding to the plurality of bases based on the number of single stages corresponding to the plurality of bases factored into the resource units of the data, the order of the single stages, and the bases of the plurality of single stages. Constructing an entire stage; Converting the data into Fourier transform data by performing each of the plurality of single stages constituting the entire stage in the order of the single stage based on the radix of the plurality of single stages respectively corresponding to the plurality of single stages. ; And Outputting the Fourier transform data. The method of claim 8, Each single stage Setting the radix of a single stage corresponding to each single stage; Dividing the data into a plurality of subgroups corresponding to the radix of the single stage, and performing Fourier transform for each of the plurality of subgroups; Generating a plurality of tweet factors by applying a scaling factor to a plurality of Fourier transformed subgroups; Generating a Fourier transform data by performing a multiplication operation on the plurality of tweet factors and the plurality of Fourier transformed subgroups; And Storing the Fourier transform data. The method of claim 9, And storing the Fourier transform data comprises outputting the Fourier transform data if the single stage is the final stage in the order of the single stage.

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