KR102564255B1 - Transmitter, receiver and controlling method thereof - Google Patents

Abstract

A transmission device is started. The transmitter inserts pilots into a frame start symbol, a frame start symbol, a data symbol, and a frame end symbol, a frame generator that generates a frame including a frame start symbol, data symbols, and a frame end symbol, It includes a pilot and reserved tone inserting unit for inserting a reserved tone so as not to overlap with the pilot insertion position, and a transmitter for transmitting a frame in which the pilot and reserved tone are inserted. Accordingly, it is possible to insert a reservation tone while avoiding a collision between a pilot and a reservation tone, and it is possible to reduce a PAPR based on the inserted pilot and reservation tone.

Description

Transmitting device, receiving device and its control method {TRANSMITTER, RECEIVER AND CONTROLLING METHOD THEREOF}

The present invention relates to a transmitting device, a receiving device, and a control method thereof, and more particularly, to a transmitting device using an OFDM scheme, a receiving device, and a control method thereof.

Recently, broadcast communication services are becoming multi-functional and high-quality broadband. In particular, with the development of electronic technology, the spread of portable broadcasting devices such as high-definition digital TVs and high-end smart phones is increasing, and accordingly, demands for various reception methods and support for various broadcasting services are increasing.

In accordance with this demand, as an example, a broadcast communication standard such as DVB-T2 (Digital Video Broadcasting the Second Generation Terrestrial) has been developed. DVB-T2 (Digital Video Broadcasting the Second Generation Terrestrial) is the second-generation European terrestrial digital broadcasting standard that has improved the performance of DVB-T, which has been adopted as a standard in more than 35 countries around the world, including Europe. -T2 applies the latest technologies such as LDPC (Low Density Parity Check) code and 256QAM modulation method to increase transmission capacity and realize high bandwidth efficiency. As a result, various high-quality services such as HDTV can be provided in a limited band. has the advantage of

However, despite the advantages of the DVB-T2 system, the OFDM system used in the DVB-T2 system has a problem of high peak to average power amplifier (PAPR) due to multi-carrier modulation. That is, since the OFDM method transmits data using multiple carriers, the amplitude of the final OFDM signal is the sum of the amplitudes of each carrier, so the amplitude varies greatly. If the phases of the carriers match, it has a very large value. . The high PAPR signal goes out of the linear operating range of the high power linear amplifier, and the signal passing through the high power linear amplifier is distorted, resulting in deterioration of system performance.

Various methods have been proposed to solve the problem of such a large PAPR of the OFDM system, including clipping techniques, coding, SLM (Selected Mapping), PTS (Partial Transmit Sequence), TI (Tone Injection), etc. There are mitigation techniques.

In the TR method, which is one of the PAPR reduction techniques described above, L tones are reserved among N subcarriers, and the reserved L tones are used to reduce PAPR without transmitting data.

1 shows a frame structure of a general broadcast communication system. A plurality of OFDM symbols compose one frame, and the pilot structure shows a distributed structure in which positions of pilots change for each OFDM symbol. Since these pilots are used for channel estimation, interference or distortion should not occur. However, in the case of using the aforementioned reservation tone, a problem occurs in which the reservation tone collides with the pilot in the frame structure of FIG. 1 .

FIG. 2 shows a case in which a collision occurs between pilots and reserved tones when one of the conventional tone reservation schemes is used in the frame structure of FIG. 1 . That is, in the case of 201, the reservation tones do not collide with the pilots, but it can be seen that collisions occur between the pilots and reservation tones of 202, 203, and 204.

While avoiding the conflict between the pilot and the reservation tone, the need to insert the reservation tone has increased.

An object of the present invention is to provide a transmitting device, a receiving device, and a control method for transmitting a reserved tone by inserting a reservation tone so as not to overlap with pilot insertion positions in a frame start symbol, data symbol, and frame end symbol.

According to an embodiment for achieving the above object, a transmitter includes a frame generator for generating a frame including a frame start symbol, a data symbol, and a frame closing symbol; A pilot and reserved tone inserter for inserting pilots into the symbol, the data symbol, and the frame end symbol, and inserting a reserved tone so as not to overlap the insertion position of the pilot, and the frame into which the pilot and reserved tone are inserted Includes a transmitter that transmits.

Here, the pilot and reserved tone inserting unit inserts the pilot into the data symbol according to a first preset layout pattern, inserts the reserved tone so as not to overlap with the insertion position of the pilot, and inserts the reserved tone into the second preset layout pattern. Accordingly, the pilot may be inserted into the frame start symbol and the frame end symbol, and the reservation tone may be inserted so as not to overlap with the insertion position of the pilot.

In addition, the preset second arrangement pattern may be determined based on the preset first arrangement pattern.

The pilot and reserved tone inserting unit inserts a first reserved tone based on the arrangement pattern of the pilot inserted into the data symbol, and additionally inserts the first reserved tone at a position shifted by a preset value from the insertion position of the first reserved tone. A second reserved tone may be inserted.

In addition, reserved tones inserted into the frame start symbol and frame end symbol may be inserted at positions defined in Table 1.

In addition, the reserved tone inserted into the data symbol may be inserted at a position defined in Table 4.

Also, the pilot may be inserted at a position defined in Table 6.

On the other hand, an IFFT unit that performs an inverse Fourier (IFFT) operation on the frame start symbol, the data symbol, and the frame end symbol into which the pilot and reservation tone are inserted, and outputs the parallel signal output from the IFFT unit as a serial signal It may further include a parallel/serial conversion unit that converts and outputs the converted signal, and a PAPR reduction unit that reduces an average power-to-maximum power ratio (PAPR) based on the pilot and reserved tones.

Here, the PAPR reduction unit may calculate a reduction amount of the average power to maximum power ratio based on the pilot and reservation tones, add the calculated average power to maximum power ratio reduction amount to the serial signal, and output the sum.

Meanwhile, a receiving device according to an embodiment of the present invention performs channel estimation based on a receiving unit receiving a frame including a frame start symbol, data symbols, and frame end symbols into which pilots and reservation tones are inserted, and the pilots, , and a signal processor for detecting data by signal processing the frame start symbol, data symbol, and frame end symbol in consideration of the position of the reserved tone, and the reserved tone is inserted so as not to overlap with the insertion position of the pilot.

Here, reserved tones inserted into the frame start symbol and frame end symbol are inserted at positions defined in Table 1.

And, the reserved tone inserted into the data symbol is inserted at a position defined in Table 4.

Also, the pilot is inserted at the position defined in Table 6.

Meanwhile, a control method of a transmitter according to an embodiment of the present invention includes generating a frame including a frame start symbol, data symbols, and a frame closing symbol, the frame start symbol , inserting a pilot into the data symbol and the frame end symbol, inserting a reserved tone so as not to overlap with the insertion position of the pilot, and transmitting the frame into which the pilot and reserved tone are inserted. can do.

Here, the step of inserting the reservation tone includes inserting the pilot into the data symbol according to a first arrangement pattern, inserting the reservation tone so as not to overlap with the insertion position of the pilot, and inserting the reservation tone in a second arrangement pattern. According to the above, the pilot may be inserted into the frame start symbol and the frame end symbol, and the reservation tone may be inserted so as not to overlap with the insertion position of the pilot.

And, the preset second arrangement pattern is determined based on the preset first arrangement pattern.

In addition, the step of inserting the reserved tone may include inserting a first reserved tone based on the arrangement pattern of the pilot inserted into the data symbol, and at a position shifted by a predetermined value from the insertion position of the first reserved tone. Additionally, a second reserved tone may be inserted.

In addition, reserved tones inserted into the frame start symbol and frame end symbol may be inserted at positions defined in Table 1.

In addition, the reserved tone inserted into the data symbol may be inserted at a position defined in Table 4.

And, the pilot may be inserted into a position defined in Table 6.

Meanwhile, a control method of a transmitter according to an embodiment of the present invention includes the steps of performing an inverse Fourier (IFFT) operation on the frame start symbol, the data symbol, and the frame end symbol into which the pilot and reservation tones are inserted, and outputting the result. , converting and outputting the parallel signal outputted through the inverse Fourier operation into a serial signal, and reducing an average power-to-maximum power ratio (PAPR) based on the pilot and reserved tones.

In the step of reducing the average power to maximum power ratio, the average power to maximum power ratio reduction amount is calculated based on the pilot and reservation tones, and the average power to maximum power ratio reduction amount calculated is added to the serial signal. can be printed out.

Meanwhile, a control method of a receiving device according to an embodiment of the present invention includes receiving a frame including a frame start symbol, data symbol, and frame end symbol into which pilots and reservation tones are inserted, and channel estimation based on the pilots. and detecting data by signal processing the frame start symbol, data symbol, and frame end symbol in consideration of the position of the reserved tone, wherein the reserved tone is inserted so as not to overlap with the insertion position of the pilot. .

Here, reserved tones inserted into the frame start symbol and frame end symbol may be inserted at positions defined in Table 1.

In addition, the reserved tone inserted into the data symbol may be inserted at a position defined in Table 4.

And, the pilot may be inserted into a position defined in Table 6.

According to various embodiments of the present invention as described above, a reservation tone can be inserted while avoiding a collision between a pilot and a reservation tone, and PAPR can be reduced based on the inserted pilot and reservation tone.

1 and 2 are diagrams for explaining the prior art.
3 is a block diagram showing the configuration of a transmission device according to an embodiment of the present invention.
4 is a diagram for explaining the structure of a frame according to an embodiment of the present invention.
5 is a diagram showing positions of scattered pilots inserted into frame start symbols, data symbols, and frame end symbols according to an embodiment of the present invention.
6 is a diagram for explaining an inserted frame structure so that scattered pilots and reserved tones do not collide with each other according to an embodiment of the present invention.
7 is a diagram illustrating an arrangement pattern of distributed pilots shifted and arranged by a preset value according to an embodiment of the present invention.
8 is a block diagram showing the detailed configuration of a transmission device according to an embodiment of the present invention.
9 is a diagram showing a detailed configuration of a PAPR reduction unit according to an embodiment of the present invention.
10 is a block diagram showing the configuration of a receiving device according to an embodiment of the present invention.
11 is a block diagram showing a detailed configuration of a signal processing unit according to an embodiment of the present invention.
12 is a flowchart for explaining a control method of a transmission device according to an embodiment of the present invention.
13 is a flowchart for explaining a control method of a receiving device according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the drawings. And, in describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of a user or operator. Therefore, the definition should be made based on the contents throughout this specification.

The pilot structure of FIG. 2 is composed of continuous pilots maintained over several OFDM symbols and scattered pilots present in one OFDM symbol and evenly distributed in the frequency domain. In this frame structure, since the position of the pilot is different for each OFDM symbol, the position of the reserved tone must also be different. Therefore, each OFDM symbol must have a different reserved tone.

However, since each OFDM symbol has different reserved tones, impulse waveforms generated with reserved tones also have different signals. Accordingly, in the OFDM system, information on all impulse waveforms must be stored in a memory, which increases the size of the memory.

The present invention proposes a method of applying a single reserved tone to a frame without having different reserved tones for each OFDM symbol. Looking at the structure of the distributed pilot in FIG. 2, it can be seen that each OFDM symbol moves at regular intervals. If the position of the reserved tone is also moved at the same interval as the distributed pilot using this characteristic, collision between the reserved tone and the distributed pilot can be avoided. can

3 is a block diagram showing the configuration of a transmission device according to an embodiment of the present invention.

According to FIG. 3 , the transmitter 300 includes a frame generator 310, a pilot and reservation tone inserter 320, and a transmitter 330.

The frame generator 310 may generate a frame including a frame start symbol, a data symbol, and a frame closing symbol.

A frame according to an embodiment of the present invention is a frame structure of an ATSC 3.0 system. Specifically, it will be described with reference to FIG. 4 .

4 is a diagram for explaining the structure of a frame according to an embodiment of the present invention.

Referring to FIG. 4 , one frame 400 includes one preamble symbol 440, one frame start symbol 410, a plurality of data symbols 420, and one frame end symbol 430.

Here, the frame 400 may correspond to a frame used in the DVB-T2 scheme, and accordingly, the T2 frame structure will be described in detail.

One T2 frame is composed of a P1 preamble symbol indicating the start position of the frame, a P2 preamble symbol transmitting an L1 signal, and data symbols transmitting a broadcast signal.

Specifically, the P1 preamble symbol is located in the first part of the T2 frame and can be used to detect the starting point of the T2 frame. In addition, the P1 preamble symbol uses a 1K FFT size and is a signal in the form of a guard interval. And, the P1 preamble symbol in the frequency domain uses 384 subcarriers out of 853 subcarriers in the 1K FFT, and can transmit 7-bit information.

The preamble symbol 440 according to an embodiment of the present invention corresponds to the above-described P1 preamble symbol and P2 preamble symbol, and can be used to perform a synchronization function by informing the start position of a frame, and also transmits an L1 signal to Can be used to detect data.

The frame start symbol 410 informs the start point of the data symbol 420, and positions of the pilot and reservation tones inserted into the frame start symbol 410 and the data symbol 420 are different from each other. This will be described later.

In addition, the end-of-frame symbol 430 indicates the end point of the data symbol 420, and the positions of pilot and reserved tones inserted into the end-of-frame symbol 430 and the data symbol 420 are different from each other, which will be described later. do.

The pilot and reserved tone inserter 320 may insert pilots into frame start symbols, data symbols, and frame end symbols, and may insert reserved tones so as not to overlap pilot insertion positions.

Here, the pilot and reservation tone inserter 320 may correspond to the pilot inserter of the DVB-T2 transmission system. The DVB-T2 transmission system may include an input processor (not shown), a BICM encoder (not shown), a frame builder (not shown), and a modulator (not shown).

Each configuration will be briefly described in that it is the same as the content defined in DVB-T2, one of the digital broadcasting standards. For details, please refer to "Digital Video Broadcasting (DVB); Frame structure channel coding and modulation for a second generation digital terrestrial television broadcasting system (DVB-T2)".

An input processor (not shown) may process an input broadcast signal to generate a signal in a baseband frame format.

A BICM encoder (not shown) performs encoding by determining an FEC coding rate and a constellation order according to a region (Fixed PHY Frame or Mobile PHY Frame) in which data to be serviced is to be transmitted. Signaling information on data to be served may be coded through a separate BICM encoder (not shown) according to implementation, or may be coded by sharing the BICM encoder (not shown) with the data to be served.

A frame builder (not shown) and a modulator (not shown) configure a frame by determining OFDM parameters for a signaling area and OFDM parameters for an area where data to be serviced is to be transmitted, and generate the frame by adding a sync area. Then, modulation is performed to modulate the generated frame into an RF signal, and the RF signal is transmitted to the receiver.

Here, the T2 frame structure may be composed of data subcarriers for transmitting signals modulated with broadcast signals, pilots for channel estimation, and reserved tones for PAPR (Peak to Average Power Ratio) reduction.

These pilot and reserved tones may be performed in a pilot insertion unit (not shown) of a modulator (not shown). Specifically, the pilot inserter (not shown) inserts a pilot of a predetermined pilot pattern into a corresponding position in a frame and outputs the pilot to an OFDM generator (not shown). The various cells within an OFDM frame are modulated with reference information of transmitted values known to the receiver. A cell containing reference information is transmitted at a boosted power level. The information transmitted from these cells is a scattered pilot cell, a continuous pilot cell, an edge pilot cell, a P2 pilot cell, or a frame-closing pilot cell. is a cell The value of pilot information is obtained from a reference sequence, which is a series of values.

Also, the pilot and reserved tone inserter 320 according to an embodiment of the present invention may correspond to a pilot inserter (not shown) of a modulator (not shown).

Also, the transmitter 330 may transmit a frame in which pilot and reservation tones are inserted.

On the other hand, the pilot and reserved tone inserter 320 inserts pilots for channel estimation and synchronization. In general, pilots include not only scattered pilots and continuous pilots, but also P2 pilots included only in P2 symbols. , a frame ending pilot of a frame closing symbol, and the like.

Scattered pilots are pilots that are constantly inserted not only in time but also in the frequency direction, and are mainly used for channel estimation and equalization. Distributed pilot patterns of existing DVB-T were constantly inserted regardless of FFT size or guard period, but DVB-T2 flexibly applies 8 patterns from PP1 to PP8 according to FFT and guard period. These patterns are designed according to the length of the maximum guard interval (1/Dx) and the channel Doppler limit (1/Dy), and since the pilot size for each pattern is 2.5 to 7.4 dB higher than that of general data, sufficient channel estimation performance is achieved. It has the advantage of being able to reduce the overhead according to pilot insertion while maintaining it.

In addition, the continuous pilot pattern is constantly inserted in the time direction, and the number of pilots inserted is relatively small compared to DVB-T, but the size of the pilot is 2.5 to 8.5 dB larger according to the FFT than that of general data, so the continuous pilot pattern In 8K, 16K, and 32K modes, the overhead due to pilot insertion was reduced from 2.5% to 0.7% without deterioration in frequency synchronization and CPE detection performance using , and the overhead was further reduced by sharing the location of some continuous pilots and dispersed pilots.

Meanwhile, according to an embodiment of the present invention, continuous pilots refer to pilots that are continuously inserted without changing positions in the frame start symbol 410, data symbol 420, and frame end symbol 430, and are scattered pilots. denotes pilots whose positions are changed and inserted according to a predetermined pattern in the frame start symbol 410, data symbol 420, and frame end symbol 430.

5 is a diagram showing positions of scattered pilots inserted into frame start symbols, data symbols, and frame end symbols according to an embodiment of the present invention.

For example, considering the case where the pilot pattern is P4,4, the scattered pilots inserted into the data symbol 420 are set to be arranged in a pattern of Dx=4 and Dy=4. This means that scattered pilots inserted into the data symbol 420 are shifted and arranged at equal intervals by a size of 4 and arranged in 4 columns.

In addition, scattered pilots inserted into the Frame Starting Symbol (FSS) 410 and the Frame Closing Symbol (FCS) 430 are set to be arranged in a pattern of Dx = 4 and Dy = 1. . This means that the scattered pilots inserted into the frame start symbol 410 and the frame end symbol 430 are arranged at equal intervals by a size of 4 and arranged in one column.

That is, an arrangement pattern of scattered pilots inserted into the data symbol 420 is different from an arrangement pattern of scattered pilots inserted into the frame start symbol 410 and the frame end symbol 430 .

Accordingly, the arrangement patterns of the reserved tones inserted into the data symbol 420 and the arrangement patterns of the reserved tones inserted into the frame start symbol 410 and the frame end symbol 430 are different from each other.

In addition, the pilot and reserved tone inserter 320 inserts a pilot into the data symbol 420 according to a first arrangement pattern, inserts a reserved tone so as not to overlap with the insertion position of the pilot, and inserts a second arrangement pattern in advance. Pilots can be inserted into the frame start symbol 410 and frame end symbol 430 according to , and reservation tones can be inserted so as not to overlap with pilot insertion positions.

Here, the second preset arrangement pattern is determined based on the first preset arrangement pattern. That is, the first preset arrangement pattern means a distribution pattern of scattered pilots inserted into the data symbol 420, and the second preset arrangement pattern refers to a distribution pattern inserted into the frame start symbol 410 and the frame end symbol 430. It can mean the pilot's deployment pattern.

Also, the preset first arrangement pattern and the preset second arrangement pattern may include an arrangement pattern including not only a dispersive pilot arrangement pattern but also a continuous pilot arrangement pattern. This is because reserved tones inserted into the frame start symbol 410, data symbol 420, and frame end symbol 430 must not overlap the insertion positions of not only scattered pilots but also continuous pilots.

That is, the pilot and reserved tone inserter 320 may insert the reserved tones into the data symbols 420 so as not to overlap with the scattered pilots and continuous pilots inserted into the data symbols 420 according to the first arrangement pattern, Reserved tones are inserted into the frame start symbol 410 and the frame end symbol 430 so as not to overlap with the scattered pilots and continuous pilots inserted into the frame start symbol 410 and the frame end symbol 430 according to the second preset arrangement pattern. can do.

When the first and second arrangement patterns include only the dispersive pilot arrangement patterns, the reservation tone may be inserted by considering the continuous pilot arrangement patterns, and the first arrangement pattern and the second arrangement patterns may include the distribution of dispersed pilots. In the case of including patterns and arrangement patterns of continuous pilots, reserved tones may be inserted in consideration of only the first arrangement pattern and the second arrangement pattern.

6 is a diagram for explaining an inserted frame structure so that scattered pilots and reserved tones do not collide with each other according to an embodiment of the present invention.

By setting the position of the reserved tones designed in the OFDM symbol to be the same as the shift interval of the scattered pilots, collisions with each other are avoided, and as mentioned above, the problem of increasing memory that occurs when one reserved tone is reused is solved. can

When the position where the reservation tone is inserted is circularly shifted in the frequency domain, the magnitude of the complex value of the impulse waveform generated by the reservation tone is not changed, but only the phase is changed. Since the phase change varies by the separation interval, the phase change according to the separation interval can be known if only the initial phase information is known. Therefore, a method of inserting a reserved tone in consideration of a pilot arrangement pattern according to an embodiment of the present invention is applicable to all OFDM symbols within a frame.

Specifically, referring to FIG. 6, the arrangement patterns of pilots inserted into the frame start symbol 610 and the frame end symbol 630 are identical to each other, and arrangement of reserved tones inserted so as not to overlap in consideration of such pilot arrangement patterns. The patterns are also the same.

On the other hand, the pilot arrangement pattern inserted into the data symbol 620 is different from the pilot arrangement pattern inserted into the frame start symbol 610 and the frame end symbol 630, and the pilot arrangement patterns are considered so as not to overlap. The arrangement pattern of the reserved tone to be used is also different from the arrangement pattern of the reserved tone inserted into the frame start symbol 610 and the frame end symbol 630.

In addition, it can be seen that the pilot and reservation tones inserted in all symbols 610, 620, and 630 shown in FIG. 6 do not overlap each other.

Meanwhile, the pilot arrangement pattern inserted into the frame start symbol 610 and the frame end symbol 630 may be determined based on the pilot arrangement pattern inserted into the data symbol 620.

For example, if the pilot arrangement pattern inserted into the data symbol 620 is Dx=4 and Dy=4, the pilot arrangement pattern inserted into the frame start symbol 610 and the frame end symbol 630 is Dx=4. , Dy = 1, which means an arrangement pattern that is arranged in one column while maintaining the shift interval of pilots to be inserted soon.

That is, the pilots inserted into the frame start symbol 610 and the frame end symbol 630 are arranged in all subcarrier positions corresponding to the pilot arrangement pattern inserted into the data symbol 620.

Meanwhile, the pilot and reserved tone inserter 320 inserts the first reserved tone based on the arrangement pattern of the pilot inserted into the data symbol 620, and the position is shifted by a preset value from the insertion position of the first reserved tone. In addition, a second reserved tone may be inserted.

Specifically, as described above, the pilot and reservation tone inserter 320 may reserve the first reservation tone so as not to overlap with the location of the pilot inserted into the data symbol 620 . Here, the inserted pilot is a concept including both scattered pilots and continuous pilots. Accordingly, the pilot and reservation tone inserter 320 may reserve the first reservation tone so as not to overlap the locations of the scattered and continuous pilots inserted into the data symbol 620 .

In addition, the pilot and reservation tone inserter 320 may additionally reserve the second reservation tone in consideration of the distribution pattern of distributed pilots. Specifically, the pilot and reservation tone inserter 320 may reserve the second reservation tone in consideration of the shift amount of the distributed pilots. This will be described in detail with reference to FIG. 7 .

7 is a diagram illustrating an arrangement pattern of distributed pilots shifted and arranged by a preset value according to an embodiment of the present invention.

Referring to FIG. 7, it can be seen that if the scattered pilots are located at intervals of 20 subcarriers, they are circularly moved at intervals of 4 subcarriers as the number of OFDM symbols increases.

Therefore, the pilot and reserved tone inserter 320 inserts the first reserved tone so as not to overlap with the scattered pilots inserted in the second column shown in FIG. 7, and the scattered pilots inserted in the first column shown in FIG. Since it is shifted by 4 subcarrier intervals based on the scattered pilots inserted in the column, the second reserved tone can be inserted at a position shifted by 4 subcarrier intervals from the insertion position of the first reserved tone inserted in the second column. .

Equation 1 below is an equation representing an insertion position of a reserved tone inserted in consideration of the above-described distributed pilot arrangement pattern.

Here, S ₀ represents the location of the reserved tone, and N _RT is Indicates the number of reserved tones.

Accordingly, the pilot and reserved tone inserting unit 320 does not have to calculate the insertion position of the reserved tone for all data symbols every time, and considers the shifted value of the scattered pilot when only the insertion position of the first reserved tone is determined. Thus, the insertion position of the second reserved tone can be determined, thereby reducing the amount of calculation and, as described above, the amount of memory for storing the impulse signal corresponding to each reserved tone can be reduced.

Meanwhile, reserved tones inserted into the frame start symbol 610 and the frame end symbol 630 may be inserted at positions defined in Table 1 below.

Table 1 is a table showing indexes indicating positions of reserved tones inserted into the frame start symbol (FSS) and the frame end symbol (FCS) according to an embodiment of the present invention. That is, the positions of the reserved tones shown in Table 1 are the frame start symbol 610 and the frame end symbol (designed by considering the insertion positions of scattered pilots and continuous pilots according to modes with FFT sizes of 8K, 16K, and 32K for each mode) 630) is the position of the reserved tone inserted.

Meanwhile, DVB-T2, a European broadcasting standard, considers various OFDM sizes, and includes 1K, 2K, 4K, 8K, 16K, and 32K modes as follows. Table 2 below shows the OFDM size, the number of data symbols, and the number of reserved tones.

1K mode 2K mode 4K mode 8K mode 16K mode 32K mode number of subcarriers 1024 2048 4096 8192 16384 32766 number of data symbols 853 1705 3409 6517 13833 27265 number of reserved tones 9 18 36 72 144 288

That is, the number of reserved tones that can be inserted and the insertion position may vary according to the above-described mode. Distributed pilots may be inserted in various modified forms according to the above-described mode while having a structure similar to that shown in FIG. 7 . For example, unlike FIG. 7, scattered pilots may be inserted at intervals of 12 subcarriers. In addition, the reservation tone may be inserted so as not to overlap with the insertion position of the dispersion pilot. Accordingly, the number and insertion position of reserved tones that can be inserted for each mode are different.

Like the reserved tones inserted differently for each mode of DVB-T2 described above, the reserved tones inserted in the frame start symbol and frame end symbol according to an embodiment of the present invention may be inserted differently for each mode.

The number of reserved tones inserted for each mode shown in Table 1 is summarized in Table 3 below.

8K mode 16K mode 32K mode number of subcarriers 8192 16384 32766 number of reserved tones 72 144 288

And, the index displayed for each mode indicates the position of the reserved tone inserted into the frame start symbol 610 and the frame end symbol 630.

It can be seen that the positions of reserved tones displayed for each mode are different.

Meanwhile, reserved tones inserted into data symbols may be inserted at positions defined in Table 4 below.

Table 4 is a table showing indexes indicating positions of reserved tones inserted into data symbols according to an embodiment of the present invention. That is, the positions of reserved tones shown in Table 4 are reserved tones inserted into data symbols 620 designed by considering the insertion positions of scattered pilots and continuous pilots according to modes with FFT sizes of 8K, 16K, and 32K for each mode. is the location of

Similarly, like the above-described reserved tones inserted differently for each mode of DVB-T2, reserved tones inserted into data symbols according to an embodiment of the present invention may be inserted differently for each mode.

The number of reserved tones inserted for each mode shown in Table 4 is summarized in Table 5 below.

8K mode 16K mode 32K mode number of subcarriers 8192 16384 32766 number of reserved tones 72 144 288

And, the index displayed for each mode indicates the position of the reserved tone inserted into the data symbol 620. Similarly, positions of reserved tones displayed for each mode are different.

Meanwhile, a pilot may be inserted at a position defined in Table 6 below.

Table 6 is a table showing indexes indicating insertion positions of continuous pilots according to modes in which FFT sizes are 8K, 16K, and 32K according to an embodiment of the present invention.

That is, the index indicating the location of the reserved tone inserted into the frame start symbol 610, the frame end symbol 630, and the data symbol 620 defined in Tables 1 and 4 is the number of consecutive pilots defined in Table 6. It is designed not to overlap with each other considering the index indicating the insertion position and the insertion position of the scattered pilots, that is, the arrangement pattern.

8 is a block diagram showing a detailed configuration of a transmission device according to an embodiment of the present invention.

Referring to FIG. 8, the transmitter 300 includes a frame generator 310, a pilot and reserved tone inserter 320, an IFFT unit 340, a parallel/serial converter 350, and a PAPR reduction unit 360. And it may include a transmitter 330.

More specifically, the pilot and reservation tone inserter 320 may be input to the pilot and reservation tone inserter 320 with input signals of N-L points and L number of reservation tone signals. Here, no data is transmitted to the L reserved tones, and 0 is inserted.

The IFFT unit 340 may perform an inverse Fourier (IFFT) operation on the frame start symbol, data symbol, and frame end symbol into which the pilot and reservation tones are inserted, and output them. Specifically, when the sum of input signals of points N-L, which are parallel signals, and L reserved tones is input to the IFFT unit 340, an IFFT operation may be performed.

The parallel/serial conversion unit 350 may convert the parallel signal output from the IFFT unit 340 into a serial signal and output the converted signal. Specifically, the parallel/serial conversion unit 350 may output a time domain output signal by converting a parallel signal into a serial signal.

The PAPR reduction unit 360 may reduce the average power to maximum power ratio (PAPR) based on the pilot and reserved tones.

Specifically, the PAPR reduction unit 360 may calculate an average power-to-maximum power ratio reduction amount based on the pilot and reserved tones, sum the calculated average power-to-maximum power ratio reduction amounts, and output the sum of the average power-to-maximum power ratio reduction amounts.

The PAPR reduction unit 360 may include a gradient algorithm unit (not shown), and the signal generated by the gradient algorithm unit (not shown) may be added to the output signal output from the IFFT unit 340 and output. . Here, the gradient algorithm unit (not shown) may reduce the average power to maximum power ratio of the output signal output from the IFFT unit 340 by using the impulse signal corresponding to the reserved tone.

Meanwhile, although not shown in FIG. 8 , the transmission device 300 may further include a memory (not shown) and a control unit (not shown).

A memory (not shown) may store information about the number of reserved tones and locations of reserved tones according to OFDM sizes. The gradient algorithm unit (not shown) generates a signal having an impulse shape using information stored in a memory, and the generated impulse signal is stored in a memory (not shown).

In addition, the memory (not shown) transmits information on the number of reserved tones and the location of the reserved tones to a control unit (not shown), and the control unit (not shown) does not collide with data and pilots according to the OFDM size and pilot position. Information on the number of reserved tones and the location of the reserved tones may be transmitted to the pilot and reserved tone inserter 320 so that the reserved tones are allocated.

Accordingly, the pilot and reservation tone inserter 320 may allocate and insert subcarriers so that the pilot and reservation tones do not collide with each other.

In addition, the control unit (not shown) may adjust the position shift of the reserved tone and the phase of the impulse signal by calculating the shift interval of the distributed pilots according to the OFDM symbol index. Even if the location of the reserved tone is circularly moved, the same PAPR reduction performance can be maintained because the size of the impulse signal does not change. In addition, the shift interval may be calculated by the pilot and reservation tone inserter 320 instead of the controller (not shown) and then sent to the controller (not shown) to calculate the phase.

9 is a diagram showing a detailed configuration of a PAPR reduction unit according to an embodiment of the present invention.

Referring to FIG. 9, the PAPR reduction unit 360 includes a P waveform generator 361, a peak detection unit 362, a position cycle moving unit 363, a phase rotation unit 364, a scaling unit 365, and a complex adder ( 366), a PAPR calculation unit 367 and a control unit 367.

The P waveform generating unit 361 may generate a P waveform having an impulse characteristic with reserved L tones, excluding the input signal of the NL point, which is a parallel signal, among the total N signals. Here, the P waveform is obtained by repeating a trial of randomly selecting at least one reserved L tone from the entire signal, and then the power value is the highest among the remaining P ₁ to P _{N - 1} values excluding the peak value of P ₀ among them. A small case was chosen.

Meanwhile, the peak detector 362 may detect the maximum peak value of the input signal at points N-L.

Then, the position circular moving unit 363 circularly moves the position of the P waveform to the position of the detected maximum peak value.

The phase rotator 364 matches the circularly shifted P waveform with the phase of the peak value detected on the complex plane.

Further, the scaling unit 365 may scale the value of the P waveform so that the peak value of the signal output after the IFFT operation of the input signal at points N-L becomes equal to or less than a preset PAPR value.

The complex adder 366 converts the input signal at point N-L to a value calculated to reduce the signal output after IFFT operation and the maximum peak value of the P waveform to a value below a preset level. It can be summed with and transmitted as an input value of the PAPR calculation unit 367.

The control unit 368 may feed back the input PAPR calculation value so that it is equal to or less than a preset PAPR value. This iteration is repeated until the input PAPR calculation value is equal to or less than the preset PAPR value.

10 is a block diagram showing the configuration of a receiving device according to an embodiment of the present invention.

Referring to FIG. 10 , a receiving device 1300 may include a receiving unit 1310 and a signal processing unit 1320.

The receiving unit 1310 may receive a frame including a frame start symbol, data symbols, and frame end symbols into which pilot and reservation tones are inserted.

The signal processing unit 1320 may perform channel estimation based on the pilot and signal-process the frame start symbol, data symbol, and frame end symbol in consideration of the location of the reserved tone to detect data. Here, the reservation tone is inserted so as not to overlap with the insertion position of the pilot.

11 is a block diagram showing a detailed configuration of a signal processing unit of a receiving device according to an embodiment of the present invention.

Referring to FIG. 11, the signal processing unit 1320 includes a parallel/serial conversion unit 1321, an FFT unit 1322, a data symbol detection unit 1323, a data demodulation unit 1324, a memory 1325, and a control unit 1326. can include

The parallel/serial conversion unit 1321 may parallelly convert the received signals over the input time and output them to the FFT unit 1332.

The FFT unit 1332 may perform Fourier transform on the input signals to convert them into frequency signals, and transmit the converted signals to the data symbol detection unit 1323.

Here, the memory 1325 outputs the previously stored locations of reserved tones inserted into the frame start symbol 610, data symbol 620, and frame end symbol 630 according to an embodiment of the present invention, and outputs them. The position of the reserved tone is input to the control unit 1326.

The controller 1326 adjusts the position of the inserted reservation tone according to the position of the pilot in the OFDM symbol received by the receiver 1310 so that it does not collide with the pilot position, and outputs the adjusted signal to the data symbol detector 1323.

The data symbol detection unit 1323 extracts the remaining signals other than the position of the reserved tone input from the control unit 1326 among the frequency signals input from the FFT unit 1322, that is, signals corresponding to data symbols. can be printed out. Accordingly, the data symbol 620 extracted by the data symbol detector 1323 is input to the data demodulator 1324 to perform a data demodulation operation.

Meanwhile, reserved tones inserted into the frame start symbol 610 and the frame end symbol 630 may be inserted at positions defined in Table 1.

Also, reserved tones inserted into the data symbol 620 may be inserted at positions defined in Table 4.

Also, pilots can be inserted at positions defined in Table 6.

12 is a flowchart for explaining a control method of a transmission device according to an embodiment of the present invention.

According to the control method of the transmitter shown in FIG. 12, a frame including a frame start symbol, data symbols, and frame closing symbols may be generated (S1510).

Subsequently, pilots may be inserted into the frame start symbol, data symbol, and frame end symbol, and reserved tones may be inserted so as not to overlap with the pilot insertion positions (S1520).

Here, the step of inserting the reserved tone includes inserting a pilot into the data symbol according to a first arrangement pattern, inserting the reservation tone so as not to overlap with the insertion position of the pilot, and inserting a frame start symbol according to a second arrangement pattern. A pilot may be inserted into the frame end symbol, and a reservation tone may be inserted so as not to overlap with the insertion position of the pilot. The second preset arrangement pattern may be determined based on the first preset arrangement pattern.

In addition, the step of inserting the reserved tone includes inserting the first reserved tone based on the arrangement pattern of the pilot inserted into the data symbol, and additionally the second reserved tone at a shift position by a preset value from the insertion position of the first reserved tone. can be inserted.

And, the frame in which the pilot and reservation tones are inserted can be transmitted (S1530).

Here, reserved tones inserted into frame start symbols and frame end symbols may be inserted at positions defined in Table 1.

In addition, reserved tones inserted into data symbols may be inserted at positions defined in Table 4.

Pilots can be inserted at positions defined in Table 6.

Meanwhile, the control method of the transmitter shown in FIG. 12 includes the steps of performing and outputting an inverse Fourier (IFFT) operation on a frame start symbol, a data symbol, and a frame end symbol into which pilot and reservation tones are inserted, and the inverse Fourier operation is performed. The method may further include converting the outputted parallel signal into a serial signal and outputting the converted signal, and reducing an average power to maximum power ratio (PAPR) based on the pilot and reserved tones.

Here, in the step of reducing the average power to maximum power ratio, the average power to maximum power ratio reduction amount may be calculated based on the pilot and reserved tones, and the average power to maximum power ratio reduction amount calculated for the serial signal may be summed and output. .

13 is a flowchart for explaining a control method of a receiving device according to an embodiment of the present invention.

According to the control method of the receiving device shown in FIG. 13, a frame including a frame start symbol, data symbol, and frame end symbol into which pilot and reservation tones are inserted can be received (S1610).

Then, channel estimation is performed based on the pilot, and data may be detected by signal processing the frame start symbol, data symbol, and frame end symbol in consideration of the location of the reserved tone (S1620).

Here, the reservation tone is inserted so as not to overlap with the insertion position of the pilot.

In addition, reserved tones inserted into frame start symbols and frame end symbols may be inserted at positions defined in Table 1.

Also, reserved tones inserted into data symbols may be inserted at positions defined in Table 4.

Also, pilots can be inserted at positions defined in Table 6.

Meanwhile, a plurality of frames received by the receiving device 200 are transmitted through the DVB-T2 transmission system, and a signaling area of the frame may be an area transmitting L1 signaling.

As described above, according to various embodiments of the present invention, information included in the signaling area increases by reconstructing information included in the signaling area, and accordingly, data can be processed in various ways.

Meanwhile, a non-transitory computer readable medium storing a program for sequentially performing the control method according to the present invention may be provided.

For example, generating a frame including a frame start symbol, data symbol, and frame end symbol, inserting pilots into the frame start symbol, data symbol, and frame end symbol, and inserting reserved tones so as not to overlap the pilot insertion positions. and a non-transitory computer readable medium storing a program performing a step of transmitting a frame in which pilot and reservation tones are inserted may be provided.

In addition, as an example, receiving a frame including a frame start symbol, data symbol, and frame end symbol into which a pilot and a reservation tone are inserted, performing channel estimation based on the pilot, and starting the frame in consideration of the position of the reservation tone A non-transitory computer readable medium in which a program performing a step of detecting data by signal processing symbols, data symbols, and frame end symbols is stored may be provided.

A non-transitory readable medium is not a medium that stores data for a short moment, such as a register, cache, or memory, but a medium that stores data semi-permanently and can be read by a device. Specifically, the various applications or programs described above may be stored and provided in a non-transitory readable medium such as a CD, DVD, hard disk, Blu-ray disk, USB, memory card, or ROM.

In addition, although a bus is not shown in the above block diagram showing the transmission device and the reception device, communication between components in the transmission device and the reception device may be performed through a bus. In addition, each device may further include a processor such as a CPU or a microprocessor that performs the various steps described above.

In addition, although preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific embodiments described above, and the technical field to which the present invention belongs without departing from the gist of the present invention claimed in the claims. Of course, various modifications are possible by those skilled in the art, and these modifications should not be individually understood from the technical spirit or perspective of the present invention.

300: transmission device 310: frame generator
320: pilot and reservation tone insertion unit 330: transmission unit
1300: receiving device 1310: receiving unit
1320: signal processing unit

Claims (8)

In the transmission method,
inserting a pilot into a frame including data symbols and at least one boundary symbol; and
Transmitting a signal generated based on the frame into which the pilot is inserted; includes,
The at least one boundary symbol includes at least one of a symbol located before a first data symbol among the data symbols and a symbol located after a last data symbol among the data symbols,
The inserting may include inserting pilots into the at least one boundary symbol based on a first pattern and inserting pilots into the data symbols based on a second pattern;
The pilot inserted into the data symbols includes a scattered pilot,
A tone for reducing a peak to average power ratio (PAPR) of the signal is inserted at a position where the pilot is not inserted in the at least one boundary symbol and the data symbols,
Wherein the position of the tone is determined based on the size of the OFDM symbol included in the frame. delete According to claim 1,
The step of inserting is
Based on the second pattern, pilots are inserted into the data symbols, and tones are inserted into the data symbols so as not to overlap positions of the pilots;
A transmission method, wherein a pilot is inserted into the at least one boundary symbol based on the first pattern, and a tone is inserted into the at least one boundary symbol so as not to overlap a position of the pilot. According to claim 1,
The first pattern is determined based on the second pattern. According to claim 1,
performing an Inverse Fast Fourier Transform (IFFT) operation on the data symbols into which the pilot and tone are inserted and the at least one boundary symbol; and
Converting a parallel signal based on the IFFT operation into a serial signal; further comprising,
Wherein the signal has a PAPR reduced based on the tone. In the receiving method,
Receiving a frame from a transmitting device; and
Processing the frame based on the position of the tone for PAPR (Peak to Average Power Ratio) reduction; includes,
The frame includes data symbols and at least one boundary symbol,
The at least one boundary symbol includes at least one of a symbol located before a first data symbol among the data symbols and a symbol located after a last data symbol among the data symbols,
Pilots are inserted into the data symbols based on a first pattern, pilots are inserted into the at least one boundary symbol based on a second pattern,
The pilot inserted into the data symbols includes a scattered pilot,
A tone for reducing the PAPR is inserted at a position where the pilot is not inserted in the at least one boundary symbol and the data symbols,
Wherein the position of the tone is determined based on the size of an OFDM symbol included in the frame. delete According to claim 6,
The first pattern is determined based on the second pattern.

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