KR20080106134A - Method for signal transmitting and apparatus for the same, method for signal receiving and apparatus for the same - Google Patents

Abstract

A method and an apparatus for transmitting and receiving a signal are provided to increase a signal transmission length by estimating a channel for a transmission channel with long delay spread and to improve data transmission rate based on a signal-to-noise ratio. Data is encoded with error correction. The error correction encoded data is mapped to data symbol(S8200). Period information to insert a first pilot symbol to a modulation frame is generated. A first modulation frame is generated so that a pilot symbol interval with the first pilot symbol and a data symbol interval with the mapped data symbol are repeated periodically in an odd carrier. A second modulation frame is generated so that the pilot symbol interval with the first pilot symbol and the data symbol interval with the mapped data symbol are repeated periodically in an even carrier. The formed first and second modulation frames are modulated in the orthogonal frequency division multiplexing method. The modulated signal is transmitted(S8204).

Description

Method for signal transmitting and apparatus for the same, Method for signal receiving and apparatus for the same

The present invention relates to a signal transmission and reception method and a signal transmission and reception apparatus, and more particularly, to a signal transmission and reception method and a transmission and reception apparatus that can improve data transmission efficiency.

Users have experienced superiority of HD (High Definition) video and digital sound due to the development of Digital Broadcasting technology, and the better environment is being developed through the continuous development of compression algorithms and high performance of hardware. Will be. The digital television (DTV) may receive the digital broadcast signal and provide various additional services in addition to video and audio to the user.

With the spread of digital broadcasting, demands for better services such as video and audio are increasing, and the size of data desired by the user and the number of broadcasting channels are gradually increasing.

However, it is difficult to cope with the increased data size or the number of broadcast channels using the conventional signal transmission / reception scheme. Accordingly, there is an increasing demand for a new signal transmission / reception technique requiring higher bandwidth efficiency of a channel than a conventional signal transmission / reception scheme and requiring a low cost of configuring a signal transmission / reception network.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a signal transmission / reception method and a transmission / reception apparatus capable of using an existing signal transmission / reception network network and increasing data transmission efficiency.

The present invention provides an error correction encoder for error correcting data, a symbol mapper for mapping the error corrected coded data to a data symbol, a pilot symbol interval in which the first pilot symbol is located only on odd carriers, and the mapped data symbols A first frame forming unit for forming a first modulation frame so that the located data symbol interval is repeated periodically, and inserts period information into which the first pilot symbol is inserted in the first modulation frame, the first pilot symbol only in even carriers A second modulation frame is formed so that the pilot symbol section located thereon and the data symbol section in which the mapped data symbol is located are periodically repeated, and inserts period information into which the first pilot symbol is inserted into the second modulation frame. Two frame forming unit, orthogonal frequency multiplexing the formed first modulation frame A first modulator for modulating a second modulator, a second modulator for modulating the formed second modulated frame by an orthogonal frequency multiplexing scheme, a first transmitter for transmitting a signal output by the first modulator, and the second modulation A signal transmission device including a second transmission unit for transmitting an additionally output signal and a signal transmission method of the device are provided.

In another aspect, the present invention provides a first demodulator and an even carrier for demodulating a signal having a pilot symbol section in which a first pilot symbol is located only on an odd carrier, and a first modulation frame configured to periodically repeat the data symbol section in which a data symbol is located. Parsing the first modulation frame, the second demodulation unit for demodulating a signal having a pilot symbol period in which the first pilot symbol is located, a second modulation frame formed so that the data symbol interval in which the data symbol is located is periodically repeated A first frame parser, a second frame parser that parses the second modulated frame, a multiple input / output decoder configured to output data symbols included in each of the first and second modulated frames as a symbol string, A symbol demapper for demapping a symbol string and error correction decoding the demapped data. It provides a current correction decoding a signal receiving apparatus including a signal receiving method and of the device.

At least one of the first modulation frame and the second modulation frame may include a second pilot symbol at a constant carrier position over time.

The second pilot symbol may be a symbol to be scrambled.

As described above, according to the signal transmission / reception method and the signal transmission / reception apparatus of the present invention, it is easy to switch to the proposed signal transmission / reception system using an existing signal transmission / reception network network, and the cost can be reduced.

In addition, the data rate can be improved based on the SNR gain, and channel estimation can be performed for a transmission channel having a long delay spread, thereby increasing the signal transmission distance. In addition, by using the proposed frame structure, more accurate channel estimation can be performed and time for TPS synchronization can be reduced.

 Therefore, there is an effect that can increase the signal transmission and reception performance of the overall transmission and reception system.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings. In addition, the terms used in the present invention was selected as a general term widely used as possible now, but in certain cases, the term is arbitrarily selected by the applicant, in which case the meaning is described in detail in the corresponding description of the invention, It is to be clear that the present invention is to be understood as the meaning of terms rather than names.

Operation of the signal transmission and reception method and the signal transmission and reception device according to the present invention configured as described above will be described in detail with reference to the accompanying drawings.

1 is a block diagram schematically showing a signal transmission apparatus according to an embodiment according to the present invention. The transmission and reception system may use MIMO (Multi Input Multi Output) for multiple input and output.

The signal transmission apparatus of FIG. 1 may be a signal transmission system for transmitting video data such as a broadcast signal. For example, it may be a signal transmission system according to a digital video broadcasting (DVB) system. An embodiment of a signal transmission system according to the present invention will be described with reference to FIG. 1.

1 illustrates an outer encoder 100, a first interleaver 110, an inner encoder 120, a second interleaver 130, and a symbol mapper 140. ), The linear precoding unit 150, the third interleaver 160, the multiple input / output encoder 170, the first frame builder 180, the second frame builder 185, the first modulator 190, a second modulator 192, a first transmitter 194, and a second transmitter 196.

The outer encoder 100 and the inner encoder 120 encode and output the input signal, thereby detecting an error in the transmitted data at the receiver and correcting the error. As the encoder, forward error correction encoding (FEC) may be used. The first interleaver 110 mixes the data streams output from the outer encoder 100 and distributes them to random positions. The first interleaver 110 may use a convolution interleaver, a block interleaver, and the like, which may vary depending on a transmission system. In addition, the first interleaver 110 may not be used depending on implementation.

2 is a block diagram schematically illustrating an interleaver and a forward error correction encoder according to an embodiment of the present invention. The forward error correction encoder includes an outer encoder and an inner encoder, a BCH (Bose-Chaudhuri-Hocquenghem) encoder 100 and a Low Density Parity Check (LDPC) encoder 120.

The LDPC code is a type of error correcting code that can reduce the probability of data loss as much as possible. The LDPC encoder 120 may increase the length of the block so that the transmission data has a characteristic that is robust to a transmission error. In addition, in order to prevent an increase in hardware complexity due to an increase in the block size, the complexity of the decoder may be reduced by decreasing the density of parity bits.

In order to prevent an error floor from occurring in the output data of the receiving side, the BCH encoder 100 is used as an additional outer encoder. If the LDPC encoder 120 is used to ignore the error floor, the BCH encoder 100 may not be used. Alternatively, an encoder other than the BCH encoder may be used as the outer encoder.

The data encoded by the BCH encoder 100 and interleaved by the first interleaver 110 are output to the second interleaver 130 via the LDPC encoder 120.

The second interleaver 130 mixes and distributes the forward error corrected data sequence to a random position so as to be robust to a burst error occurring during transmission. The second interleaver 130 may use a convolution interleaver, a block interleaver, and the like, which may vary depending on a transmission system.

3 is a diagram illustrating an interleaver for interleaving input data according to an embodiment of the present invention. 3 is an example of an interleaver that can be used for the second interleaver 130 as a type of block interleaver.

The interleaver of FIG. 3 stores data input to a matrix-type storage space in a predetermined pattern and reads and outputs the data in a pattern different from the storage pattern. For example, the interleaver of FIG. 3 has a storage space (Nr × Nc) consisting of a row of Nr and a column of Nc, and data input to the interleaver is filled from the position of one column, one row of the storage space. Data is stored starting from row 1 of column 1 up to row Nr of column 1, and when the column 1 is filled up, data is stored starting from row 1 of the next column (column 2) up to row Nr. Data can be stored up to Nr rows of Nc columns in the above order.

When reading the data stored in the storage space, the data of the row is read and output from the data of the first row to the first column of the storage space up to the first row Nc column. If all the data of the row is read, starting from the first column of the next lower row (row 2), the data of the row is read and output in the right direction. Data can be read and output up to Nc columns of Nr rows in the same order as described above. At this time, the MSB (Most Significant Bit) position of the data block is at the top left, and the LSB (Least Significant Bit) position is at the bottom right.

A size, a storage pattern, a read pattern, and the like of the storage block of the interleaver are one embodiment, which may vary depending on the implementation.

Data interleaved by the second interleaver 130 is input to the symbol mapper 140. The symbol mapper 140 may map a transmission signal to a symbol in consideration of a pilot signal and a transmission parameter signal according to a transmission mode. Quadrature Amplitude Modulation (QAM), Quadrature Phase Shift Keying (QPSK), Amplitude Phase Shift Keying (APSK), Pulse Amplitude Modulation (PAM), and Optimal Constellation may be used as the mapping scheme. Alternatively, an encoded symbol mapping method may be used for the symbol mapper 140. For example, it may be mapped to a coded symbol using a method such as trellis code modulation.

The linear precoding unit 150 distributes the input symbol data to a plurality of output symbol data, thereby reducing the probability that all information is lost due to fading when experiencing a frequency selective fading channel. The linear precoding unit 150 converts the input data into parallel data, distributes the data to multiple data through encoding matrixing, and converts the data into serial data and outputs the serial data.

The encoding matrix is designed to compare an output symbol with an input symbol so that Pairwise Error Probability (PEP), which is a probability that the two symbols are wrong, is minimized. Designed to minimize PEP, the diversity gain and coding gain obtained through linear precoding can be maximized. In addition, when the minimum Euclidean distance of a linear precoded symbol is maximized through the encoding matrix, an error probability may be minimized when the receiver uses a maximum likelihood (ML) decoder.

As an example of the encoding matrix, a vanderMonde matrix, a Hadamard matrix, a golden code, or the like may be used. The matrix is an example, and according to an embodiment, the data may be distributed using an appropriate matrix.

In addition, the linear precoding unit 150 may not be used depending on implementation.

The third interleaver 160 interleaves the symbol data output from the linear precoding unit 150 again. That is, interleaving is performed in the third interleaver 160 so that symbol data dispersed in the data output from the linear precoding unit 150 does not experience the same frequency selective fading. A convolution interleaver, a block interleaver, or the like may be used for the third interleaver 160.

4 is a diagram illustrating an example of an interleaver according to an embodiment of the present invention. The interleaver of FIG. 4 may be used in the third interleaver 160 of the transmitting apparatus as shown in FIG. 1 as an embodiment of the interleaver for the OFDM system having the symbol length N.

N represents the length of the interleaver, i has a value equal to the length of the interleaver, that is, an integer value from 0 to N-1. n has the number of effective transport carriers in the transmission system. ∏ (i) denotes a permutation of modulo-N operations, and d _n has values of ∏ (i) in the effective transport carrier region in order except N / 2 values. k represents the index value of the actual transport carrier, so that d / 2 is subtracted from d _n so that the center of the transmission bandwidth is DC. P is a permutation constant and may vary depending on the embodiment.

5 is a diagram illustrating a specific example of the interleaver of FIG. 4 as an embodiment according to the present invention. In the example of FIG. 5, the length of an OFDM symbol and the length N of an interleaver are set to 2048, and the number of effective transmission carriers is set to 1536 (1792-256).

Therefore, i is an integer of 0-2047, n is an integer of 0-1535. ∏ (i) is a permutation of modulo-2048 operations, and d _n has a value of ∏ (i) in order except 1024 (N / 2) for a value of 256 ≦ ∏ (i) ≦ 1792. k is a value obtained by subtracting 1024 from d _n . P has 13.

Since the data k corresponding to the input data i is output using the interleaver as described above, the data of the length N of the interleaver can be mixed and transmitted.

The linear precoding unit 150 and the third interleaver 160 process the data to be transmitted to be robust to the frequency selective fading of the channel.

The multiple input / output encoder 170 encodes the data interleaved by the third interleaver 160 to be carried on a plurality of transmission antennas. There are two types of multiple input / output encoding methods, spatial multiplexing and spatial diversity. Spatial multiplexing is a method in which multiple antennas are transmitted to a transmitter and a receiver to transmit different data at the same time, thereby transmitting data at higher speed without further increasing the bandwidth of the system. Spatial diversity is a method of obtaining transmit diversity by transmitting data of the same information from multiple transmit antennas.

In this case, as the multiple diversity input / output encoder 170 having a spatial diversity scheme, a space-time block code (STBC), a space-frequency block code (SFBC), a space-time trellis code (STTC), or the like may be used. The spatial multiplex multiple input / output encoder 170 simply transmits data streams by separating the number of transmit antennas, and provides full-diversity full-rate (FDFR) code, linear dispersion code (LDC), and V-BLAST. (Vertical-Bell Lab. Layered space-time) and D-BLAST (diagonal-BLAST) can be used.

6 is a diagram illustrating an example of a multiple input / output encoding scheme according to an embodiment of the present invention. The embodiment of FIG. 6 is STBC, which is one of multiple input / output encoding schemes, and may be used in the transmission apparatus of FIG. 1. The encoding scheme is one example, and the application of other multiple input / output encoding schemes is not excluded.

In the example of the STBC encoder, T denotes a symbol transmission period, s denotes an input symbol to be transmitted, and y denotes an output symbol. * Denotes a complex conjugate, and Tx # 1 and Tx # 2 denote transmission antennas 1 and 2, respectively.

According to the above example, at time t Tx # 1 transmits s ₀ , Tx # 2 transmits s ₁ , and at time t + T Tx # 1 transmits -s ₁ ^* and Tx # 2 transmits s ₀ ^* do. Each transmitting antenna transmits data of the same information of s ₀ and s ₁ within a transmission period. Accordingly, it can be seen that the encoding scheme is one of spatial diversity schemes.

The multiple input / output encoder 170 encodes and outputs the input symbol data to be carried on a plurality of transmission antennas. For example, when there are two transmission paths, the multiple input / output encoder 170 outputs the encoded data to the first frame forming unit 180 or the second frame forming unit 185. The number of the transmission paths is only an example and may have several transmission paths according to a multiple input / output encoding scheme.

The first frame forming unit 180 and the second frame forming unit 185 insert pilot signals to modulate the signals output from the multiple input / output encoder 170 in an orthogonal frequency division multiplex (OFDM) scheme. To form a frame.

7 is a diagram illustrating a structure of a transmission frame according to an embodiment of the present invention. The transmission frame is composed of a pilot symbol period including pilot carrier information and a data symbol period including only data information.

In FIG. 7, one frame includes M intervals, and is divided into M-1 data symbol intervals and one pilot symbol interval used as a preamble. The frame having the above structure is repeated.

Each symbol period includes carrier information as many as the number of subcarriers of an Orthogonal Frequency Division Multiplex (OFDM) scheme. The pilot carrier information of the pilot symbol interval is composed of random data in order to lower the peak to average power ratio (PAPR). The pilot carrier information has a form in which auto-correlation is an impulse in the frequency domain.

Pilot carrier information is not included in the data symbol interval, and thus data capacity can be increased. In the case of DVB (Digital Video Broadcasting), for example, since the pilot carrier occupies about 10% of the total effective carriers, the increase rate of data capacity is expressed by Equation 1 below.

In Equation 1, Δ represents an increase rate, and M is the number of sections included in one frame.

When the transmission system of FIG. 1 performs multiple input / output encoding using a plurality of antennas, a structure of a pilot symbol should be determined so that each transmission path can be distinguished from a receiver.

8 (a) is a diagram showing the structure of a pilot symbol interval according to an embodiment of the present invention. The structure of the pilot symbol interval of FIG. 8 (a) may be used when multiple input / output encoding is performed to have two transmission paths as shown in FIG.

In the case of FIG. 8A, pilot carrier information is interleaved and divided into even and odd pilots in order to distinguish two transmission paths. For example, frame data including even pilot carrier information in a pilot symbol period is transmitted through antenna 0, and frame data including odd pilot carrier information in a pilot symbol period is transmitted through antenna 1. do. Accordingly, the receiving side can distinguish each transmission path using the corresponding carrier index of the pilot symbol interval.

In the above embodiment, a channel corresponding to half of subcarriers may be estimated in one symbol. Therefore, high channel estimation performance can be obtained even for a transmission channel having a short coherence time.

8 (b) is a diagram illustrating another structure of a pilot symbol period according to an embodiment of the present invention. 8 (b) may be used when multiple input / output encoding is performed to have two transmission paths as shown in FIG.

8 (b) shows an embodiment of a Hadamard type pilot symbol interval. In the above embodiment, Hadamard transformation is performed in units of symbol intervals to distinguish two transmission paths. Accordingly, the even symbol interval includes the sum of two pilot carrier information for each transmission path, and the odd symbol interval includes the difference between two pilot carrier information.

For example, the even symbol interval includes a pilot value of a carrier (a) to be transmitted through antenna 0 and a pilot value of pilot carrier information (b) to be transmitted through antenna 1 (a + b). And a difference value ab of pilot carrier information a to be transmitted through the first antenna and pilot carrier information b to be transmitted through the first antenna. If the receiving side knows the sum / difference of the two pilot carrier information through the received pilot index, each transmission path can be distinguished.

In the above embodiment, since channels corresponding to all subcarriers can be estimated, delay spread of a channel that can be processed for each transmission path can be extended by a symbol length.

8 (b) is a diagram for easily distinguishing the two pilot carrier information, and shows both pilot carrier information in the frequency domain. In the case of the even symbol interval and the odd symbol interval diagram, impulses of two pilot carrier information are located at the same frequency point. In the case of the even-symbol interval diagram, the positions of the pilot carrier information to be transmitted through the antenna 0 and the pilot carrier information to be transmitted through the antenna 1 are shown to be different for ease of division, and the pilot carrier information is located at the same frequency point. Located.

8 (a) and 8 (b) are examples of two transmission paths, and when the transmission path is longer, pilot carrier information may be distinguished by the number of transmission paths, not odd or even. You can divide or perform Hadamard transformation on a symbol interval basis.

The first modulator 190 and the second modulator 192 respectively transmit data output from the first frame former 180 and the second frame former 185 to subcarriers of OFDM. A guard interval is modulated by inserting a guard interval for transmission.

The first transmitter 194 and the second transmitter 196 respectively convert a digital signal having a guard interval and a data interval output from the first modulator 190 and the second modulator 192 into analog signals. Convert, and transmit the converted analog signal.

The signal transmission apparatus of FIG. 1 described above is an example, and a required component may be further added or an unnecessary component may not be used according to a transmission system.

9 is a block diagram schematically illustrating an apparatus for receiving a signal according to an embodiment of the present invention. 9 may be included in a DVB receiver or the like.

9 illustrates a first receiver 900, a second receiver 905, a first synchronizer 910, a second synchronizer 915, a first demodulator 920, and a second receiver. A demodulator 925, a first frame parser 930, a second frame parser 935, a multiple input / output decoder 940, a first deinterleaver 950, a linear precoding decoder 960, a symbol demapper 970, a second deinterleaver 980, an inner decoder 990, a third deinterleaver 992, and an outer decoder 994. The embodiment of FIG. 9 uses two receive paths for convenience of description, and the number of receive paths is not determined.

The first receiver 900 and the second receiver 905 each receive an RF signal, down-convert the frequency band, and convert the digital signal into a digital signal. The first synchronizer 910 and the second synchronizer 915 obtain and synchronize the frequency domain and the time domain of the received signal output from the first receiver 900 and the second receiver 905, respectively. The first synchronization unit 910 and the second synchronization unit 915 are offsets of the frequency domain of data output from the first demodulator 920 and the second demodulator 925, respectively, in order to obtain synchronization of the frequency domain signal. (offset) results are available.

The first demodulator 920 demodulates the received data output from the first synchronizer 910. To this end, the first demodulator 920 converts the received data into the frequency domain, and decodes the data value distributed in the subcarriers into a value assigned to each subcarrier. The second demodulator 925 demodulates the received data output from the second synchronizer 915.

The first frame parser 930 and the second frame parser 935 distinguish the reception paths according to the frame structures of the signals demodulated by the first demodulator 920 and the second demodulator 925, respectively. It is possible to output symbol data of a data symbol section excluding the idle symbol.

The multiple input / output decoder 940 receives and decodes the data output from the first frame parser 930 and the second frame parser 935, respectively, and outputs one data string. The multiple input / output decoder 940 outputs one data string by decoding according to a scheme corresponding to a scheme encoded by the multiple input / output encoder 170 of FIG.

10 is a diagram illustrating an example of a multiple input / output decoding scheme according to an embodiment of the present invention. FIG. 10 illustrates an example of decoding corresponding to a receiving side when the data is transmitted by multiple input / output encoding using the STBC method in the transmitting side, and the transmitting side uses two transmitting antennas. This is an example and the application of other multiple input / output methods is not excluded.

R (k), h (k), s (k), and n (k) in the above equations represent symbols received at the receiver, channel response, symbol values transmitted at the transmitter, and channel noise, respectively. Subscripts s, i, 0, and 1 denote an sth transmission symbol, an ith reception antenna, a 0th transmission antenna, and a 1st transmission antenna, respectively. '*' Represents a complex conjugate. For example, h _{s , 1, i} (k) indicates a response of the channel experienced by the transmitted symbol when the s-th transmitted symbol is received by the i-th reception antenna. r _{s + 1, i} (k) represents the s + 1 th received symbol received at the i th receive antenna.

According to the equation of FIG. 10, r _{s , i} (k) _, which is the s-th reception symbol received at the i-th reception antenna, is the s-th symbol value transmitted through the channel from the 0th transmission antenna to the i-th reception antenna, and the 1st In the transmitting antenna, the i-th receiving antenna is the sum of the s-th symbol value transmitted through the channel and the sum of the channel noise of each channel (n _s (k)).

In addition, r _{s + 1, i} (k), which is the s + 1 th received symbol received at the i th receive antenna, is the s + 1 th symbol value transmitted through the channel from the 0 th transmit antenna to the i th receive antenna, and the first transmit It is the sum of the s + 1th symbol value transmitted through the channel and the sum of the channel noise of each channel (n _s (k)).

11 is a diagram illustrating a specific example of FIG. 10 as an embodiment according to the present invention. 11 is an example of decoding when a transmitter transmits data by multiple input / output encoding using STBC, and the transmitter transmits data using two transmit antennas and receives through one antenna. to be. When two transmitting antennas are used at the transmitting side, there may be two transmission channels for one antenna at the receiving side.

H ₀ and s ₀ in the above equations represent the transmission channel response from the transmitting antenna 0 to the receiving antenna and the symbols transmitted from the transmitting antenna 0, respectively, and h ₁ and s ₁ are received from the transmitting antenna 1 respectively. The transmission channel response to the antenna and the symbol transmitted by the first antenna at the transmitting side are shown. '*' Represents a complex conjugate, and s ₀ 'and s ₁ ' in the following formulas represent a restored symbol.

And r ₀ and r ₁ represent symbols received at the receiving antenna at t time and symbols received at the receiving antenna at t + T time after the transmission period T, respectively, and n ₀ and n ₁ are the respective reception times. Denotes the sum of channel noise of each transmission path.

As shown in Equation 11 of FIG. 11, the signal received by the receiving antenna may be expressed as a value obtained by adding a value that the signal transmitted by each transmitting antenna has experienced each transmission channel. The recovered symbol is calculated using the received value and each channel response value.

The first deinterleaver 950 performs de-interleaving on the data string output from the multiple input / output decoder 940 to restore the data in the order before interleaving. The first deinterleaver 950 restores the data sequence by deinterleaving according to a method corresponding to the method interleaved by the third interleaver 160 of FIG. 1.

The linear precoding decoder 1360 restores data by performing an inverse process of distributing data in the signal transmission apparatus. The linear precoding decoder 1360 performs decoding in a manner corresponding to the encoding scheme of the linear precoding unit 150 of FIG. 1.

The linear precoding decoder 1360 converts the input data into parallel data and then restores original data from data distributed through decoding matrixing. The decoding matrix for performing the decoding may use an inverse matrix of the encoding matrix of the signal transmission apparatus. Alternatively, the received symbol data may be decoded to maximize the Like Likehood (ML) to correspond to the transmission scheme, thereby recovering original data distributed in the parallel data. That is, the received symbol data may be ML decoded in consideration of an encoding rule at the transmitter. The restored data is converted into serial data and output again.

The linear precoding decoder 1360 may or may not be used at the receiving side, depending on whether the linear precoding unit 150 is used at the transmitting side.

The symbol demapper 970 may restore the symbol data decoded by the linear precoding decoder 960 into a bit string. The second deinterleaver 980 performs de-interleaving on the data string output from the symbol demapper 970 to restore the data in the order before interleaving. The second deinterleaver 980 restores the order of the data columns by deinterleaving according to a method corresponding to the method interleaved by the second interleaver 130 of FIG. 1.

The inner decoder 990 and the outer decoder 994 may forward error correct and decode the data whose order is restored, respectively, to detect an error occurring in the received data and correct the error. The third deinterleaver 992 deinterleaves the data decoded and output by the inner decoder 990 to restore the order of the data. The third deinterleaver 992 performs deinterleaving according to a method corresponding to the method interleaved by the first interleaver 110 of FIG. 1. Similarly, the third deinterleaver 992 may or may not be used at the receiving side depending on whether the first interleaver 110 is used.

12 is a block diagram schematically illustrating a deinterleaver and a forward error correction decoder according to an embodiment of the present invention. The inner decoder 990, the third deinterleaver 992, and the outer decoder 994 correspond to the inner encoder 120, the first interleaver 110, and the outer encoder 100 of FIG. 1, respectively. The decoder includes an LDPC decoder 990 and a BCH decoder 994 as an inner decoder and an outer decoder.

The LDPC decoder 990 detects a transmission error occurring in the channel, corrects the error, and the third deinterleaver 992 deinterleaves the input data and outputs the data. The BCH decoder 994 corrects a residual error of the data decoded by the LDPC decoder 990 to remove an error floor.

13 is a block diagram schematically showing another example of a signal transmission apparatus as an embodiment according to the present invention. 14 is a block diagram schematically showing another example of a signal receiving apparatus according to an embodiment of the present invention.

13 and 14 illustrate an example applied to a system of a single input single output (SISO) system rather than a multiple input / output system.

The signal transmitting apparatus of FIG. 13 includes an outer encoder 1300, a first interleaver 1310, an inner encoder 1320, a second interleaver 1330, a symbol mapper 1340, and a linear precoding unit 1350. ), A third interleaver 1360, a frame builder 1370, a modulator 1380, and a transmitter 1390.

The signal receiver of FIG. 14 includes a receiver 1400, a synchronizer 1410, a demodulator 1420, a frame parsing unit 1430, a first deinterleaver 1440, and a linear precoding decoder ( 1450, a symbol demapper 1460, a second deinterleaver 1470, an inner decoder 1480, a third deinterleaver 1490, and an outer decoder 1495.

The signal transmission device and the signal reception device go through the processing as described with reference to FIGS. 1 and 9, respectively. However, in the transceivers of FIGS. 13 and 14, since a single input single output method is used instead of a multiple input / output method, a multiple input / output encoding process and a multiple input / output decoding process are not used.

That is, the symbol data that has been interleaved by the third interleaver 1370 to be robust to the frequency selective fading of the channel is input to the frame forming unit 1370, and the frame forming unit 1370 uses the input symbol data to make a frame. Form data and output it. Similarly, the first interleaving process or the linear precoding process may not be used depending on implementation. In the single input single output method, it is not necessary to distinguish transmission paths according to multiple inputs and outputs as shown in FIGS. 8A and 8B.

In the case of the signal receiving apparatus, the symbol parsed by the frame parsing unit 1430 is output to the first deinterleaver 1440 to perform the reverse process of processing to make the transmitting apparatus robust to frequency selective fading of the channel. Do it.

In the signal transmission apparatus of FIG. 1 or 13, the symbol mapper 140 or 1340 may symbol-map the input signal according to an optimal constellation scheme and output the symbol.

FIG. 15 is a diagram schematically illustrating a position of an optimal constellation point according to an embodiment of the present invention. The point may be used for optical constellation mapping. The number of constellation points represents power.

의 정수배가 될 수 있다.The x-axis value of the optical constellation points may be odd (1, 3, 5, ...) or even (2, 4, 6, ...), the y-axis value

It can be an integer multiple of.

,

,

의 값을 가지며, 파워는 각각 3, 27, 75, … 이다. 파워가 13인 포인트의 경우, x축 값은 1이고, y축 값은

이다. 파워가 7인 포인트의 경우, x축 값은 2이고, y축 값은

이다. For example, for points located on the x-axis, 1, 3, 5,... Power values are 1, 9, 25,... to be. for points on the y axis

,

,

And the powers are 3, 27, 75,... to be. For points with a power of 13, the x-axis value is 1 and the y-axis value is

to be. For points with power of 7, the x-axis value is 2 and the y-axis value is

to be.

As described above, by placing the point as close to the circle as possible and as far as possible from the DC position, the transmission power can be used efficiently.

In addition to the positions of the points shown in FIG. 15, a position obtained by symmetrical with respect to the x-axis, the y-axis, or the origin may be used. Alternatively, the positions obtained by rotating the positions of the points at arbitrary angles about the origin may be used. This may vary depending on implementation.

FIG. 16 is a flowchart illustrating a procedure of determining an optical constellation point according to an embodiment of the present invention. The necessary number of optical constellation points are obtained among the constellation points as shown in FIG. 15.

First, a constellation point having the smallest power among constellation points as shown in FIG. 15 is selected (S1600). In operation S1610, the number of the selected constellation points and the number of necessary constellation points are compared. If the selected number of constellation points is smaller, step S1600 is performed again to select constellation points having the smallest power among the unselected points. If the selected number of constellation points is larger, the constellation points are removed in order of increasing power by the number of points exceeded (S1620). Through the above process, a desired number of constellation points can be obtained, and input data can be mapped to symbol data using the obtained constellation points.

17 to 20 are diagrams illustrating an optical constellation having a point selected according to the above-described exemplary embodiment according to the present invention. That is, FIGS. 17 to 20 schematically illustrate an optical constellation having 16 points, 64 points, 256 points, and 256 points, respectively. 19 is a case of another embodiment having a position different from that of the constellation point described with reference to FIG. 15, and has a constellation point close to the DC position.

As described above, in addition to the positions of the points of FIGS. 17 to 20, positions obtained by symmetry of the points with respect to the x-axis, the y-axis, or the origin may be used. Alternatively, the positions obtained by rotating the positions of the points at arbitrary angles about the origin may be used. This may vary depending on implementation.

The symbol mapper 140 or 1340 symbol-maps the input data and outputs the data according to the optical constellation mapping method having a predetermined number of points as described above.

In the case of symbol mapping according to the optical constellation scheme as described above, in the signal receiving apparatus of FIG. 9 or 14, the symbol demapper 970 or 1460 may symbolize an input signal according to an optimal constellation scheme. Demap and print For convenience of explanation, it is assumed that symbol data is mapped according to an optical constellation mapping method having 64 points in the symbol mapper 140 or 1340 of FIG. 1 or 13. The number of points is only one embodiment determined for convenience of description.

21 is a block diagram schematically illustrating a decision boundary of an optical constellation having 64 points. The symbol demapper 970 or 1460 demaps the received symbol data using the decision boundary shown in FIG. 21. In the case of the optical constellation mapping scheme, the constellation has a honeycomb constellation in order to efficiently use transmission power, and the symbol demapper 970 or 1460 has hexagonal crystal boundaries for each symbol as shown in FIG. 21. However, the symbol corresponding to the point located at the edge has a crystal boundary of one side that is not hexagonal.

If it is recognized that the input symbol data is located in a specific hexagon among the crystal boundaries as shown in FIG. 21, the symbol demapper 970 or 1460 demaps the input symbol data into a symbol of a point corresponding to the specific hexagon.

22A is a diagram schematically illustrating a symbol demapper for demapping a received optical constellation symbol according to an embodiment of the present invention, and FIG. 22B is a diagram illustrating a received optical constellation symbol as an embodiment according to the present invention. FIG. Is a diagram schematically illustrating another symbol demapper to be mapped.

The symbol demapper 970 or 1460 may perform symbol demapping using the entire crystal boundary of the optical property as shown in FIG. 21 at once, or use a rectangular crystal boundary as in the symbol demapper of FIGS. 22A and 22B. Symbol demapping.

The symbol demapper of FIG. 22A includes a first determination unit 2200, a second determination unit 2202, a first rotation unit 2204, a third determination unit 2206, a fourth determination unit 2208, and a second rotation unit. 2210, a fifth decision unit 2212, a sixth decision unit 2214, and a bit converter 2216.

When symbol data is input to the symbol demapper 970 or 1460, the first determination unit 2200 uses the rectangular crystal boundary region using two faces facing each other in the hexagonal crystal boundary region to input the symbol data. Determines whether is located in the crystal boundary region of the rectangular shape. The second decision unit 2202 makes a determination as to whether the input symbol data is located in a constellation edge region, that is, in an edge region which does not form a shape on the entire crystal boundary as shown in FIG. 21. The second determination unit 2202 determines whether the second determination unit 2202 is located in a crystal boundary region divided by a solid line among the edge regions. The first determination unit 2200 and the second determination unit 2202 are determination units that determine the position of the input symbol data by using a non-rotating decision boundary.

The first rotating unit 2204 rotates the entire crystal boundary used by the first determining unit 2200 and the second determining unit 2202 by 60 degrees. Data output from the first rotating unit 2204 is input to the third determining unit 2206. The third crystal part 2206 uses a rectangular crystal boundary region using two faces facing each of the hexagonal crystal boundary regions among the entire crystal boundary regions rotated by 60 degrees, so that the input symbol data is in the rectangular form. Determine if it is located in the boundary area of the decision. The fourth decision unit 2208 determines whether the input symbol data is located in the constellation edge region. The fourth determination unit 2208 determines whether the fourth determination unit 2208 is located in a crystal boundary region divided by a dashed-dotted line among the edge regions. The third determination unit 2206 and the fourth determination unit 2208 are determination units that determine the position of the input symbol data by using the determination boundary rotated once, that is, rotated by 60 degrees.

The second rotating part 2210 rotates the entire crystal boundary used by the third and second crystal parts 2206 and 2208 by 60 degrees. Data output from the second rotating unit 2210 is input to the fifth determining unit 2212. The fifth decision unit 2212 uses the rectangular crystal boundary using two faces facing each of the hexagonal crystal boundary regions among the entire crystal boundary regions rotated by 60 degrees again, so that the input symbol data is determined in the rectangular form. Determine if you are at the boundary. The sixth decision unit 2214 determines whether the input symbol data is located in the constellation edge region. The sixth determination unit 2214 determines whether the sixth determination unit 2214 is located in a crystal boundary region divided by a dotted line among the edge regions. The fifth determination unit 2212 and the sixth determination unit 2214 are determination units that determine the position of the input symbol data by using a determination boundary that is rotated twice, that is, rotated 120 degrees relative to the original determination boundary. .

When the second crystal part 2202, the fourth crystal part 2208, and the sixth crystal part 2214 determine the edge region of the constellation, the decision on the position parallel to the x-axis and the y-axis is performed. The saturation technique is used, and the determination of the position of the oblique form is determined using the linear equation corresponding to the oblique line.

The bit converter 2216 converts the information determined by the determination units, that is, the input symbol data into the bit data corresponding to the determined symbol value by using a value determined as a symbol of a corresponding point.

As described above, both the two rotations and the six decision processes may be performed. If a symbol of a point corresponding to the received symbol data is determined by a specific decision among the six determinations, no further rotation or determination is performed. The decision information may be directly output to the bit converter 2216 and converted into bit data. This may vary depending on implementation. In addition, although the crystal boundaries are rotated by 60 degrees in each of the rotating units, they may be rotated by -60 degrees in the reverse direction.

FIG. 22B is a diagram schematically illustrating another symbol demapper for demapping a received optical constellation symbol according to an embodiment of the present invention. The symbol demapper of FIG. 22B is an embodiment of a recursive decoding method using feedback.

The symbol demapper of FIG. 22B includes a buffer 2220, a selector 2222, a first determiner 2224, a second determiner 2226, a rotater 2228, and a bit converter 2230. .

The buffer 2220 temporarily stores and outputs the input symbol data. The selector 2222 receives the symbol data output from the buffer 2220 and the symbol data output from the rotation unit 2228 and outputs one symbol data. The selector 2222 outputs symbol data fed back from the rotation unit 2228 when performing the repeated decoding, and when the decision process is performed on new symbol data, the selector 2222 outputs the symbol data input from the buffer 2220. Output

The first determination unit 2224 determines whether the input symbol data is located in the rectangular crystal boundary region by using a rectangular crystal boundary region using two faces facing each of the hexagonal crystal boundary regions. The second determination unit 2226 determines whether the input symbol data is located in a constellation edge region, that is, in an edge region which does not form a shape on the entire crystal boundary as shown in FIG. 21. The second determination unit 2226 determines whether the second determination unit 2226 is located in a crystal boundary region divided by a solid line (0 rotation), a dashed chain (1 rotation), and a dotted line (2 rotation), respectively. The rotating unit 2228 rotates the entire crystal boundary used by the first and second determination units 2224 and 2226 by 60 degrees. Or, it may be rotated by -60 degrees depending on the embodiment.

The bit converter 2230 converts the information determined by each determiner, that is, the input symbol data into a bit data corresponding to the determined symbol value by using a value determined as a symbol of a corresponding point.

The symbol demapper of 22b may perform both two rotations and six determinations. The symbol demapper of the 22b may correspond to the input symbol data in the first determination unit 2224 and the second determination unit 2226 during an iterative decoding process. When the symbol of the point to be determined is determined, the determination information may be immediately output to the bit converter 2230 to be converted into bit data. This may vary depending on implementation.

FIG. 23 is a diagram schematically illustrating a process of demapping a received optical constellation symbol according to an embodiment of the present invention, and FIG. 24 is a diagram illustrating received optical of an edge region as an embodiment according to the present invention. A diagram schematically illustrating a process of demapping constellation symbols.

FIG. 23 is a view showing four hexagonal crystal boundary regions among the entire crystal boundaries. The figure determines whether symbol data is located in the rectangular crystal boundary region by using a rectangular crystal boundary region using two faces facing each other in the hexagonal crystal boundary region among the crystal portions of FIG. 22A or 22B. The decision process of the decision part is shown.

First, in the first non-rotating crystal boundary form, the input symbol data is positioned in the rectangular crystal boundary region using a rectangular crystal boundary region using two opposite sides of the hexagonal crystal boundary region. Determine. After the determination is completed, the entire crystal boundary is rotated by 60 degrees, and the input symbol data is converted into the rectangular crystal boundary by using a rectangular crystal boundary region using two opposite sides of each hexagonal crystal boundary region. Determine if it is included in the zone. Then, the entire crystal boundary is rotated by 60 degrees again to determine whether the input symbol data is included in the rectangular crystal boundary region by using the rectangular crystal boundary using two opposite sides of the hexagonal crystal boundary region. do. In FIG. 23, the second crystal boundary shape and the third crystal boundary shape overlap with each other in the region undergoing the decision process while the rotation is performed.

Through two rotations as described above, the rectangular crystal boundary region may cover all regions inside the hexagon. Therefore, for each of the hexagonal crystal boundary regions, it is possible to demap to a symbol corresponding to a point having the hexagonal crystal boundary region.

According to an embodiment, if it is recognized that the input symbol data is located in the crystal boundary region of the rectangular shape, the determination process may be completed without performing the remaining rotation and determination. In the above description, although a rectangular crystal boundary region using two opposite sides of a hexagon is used, an area using two opposite sides other than the left and right sides, for example, an obliquely inclined rectangular boundary region, is used. Can also be used.

24 is a diagram illustrating an entire decision boundary of the 64-point optical constellation mapping method. FIG. 24 illustrates a determination process of a decision unit for making a determination as to whether the symbol data input among the determination units of FIGS. 22A and 22B is located in a constellation edge region, that is, an edge region that does not form a figure.

First, in the first non-rotating decision boundary form, it is determined whether the input symbol data is located in a region separated by a solid line among the constellation boundary regions. After the determination is completed, the entire crystal boundary is rotated by 60 degrees to determine whether it is located in a region separated by a dashed line among constellation boundary regions. Then, the entire crystal boundary is rotated 60 degrees again to determine whether it is located in the area divided by a dotted line.

According to an embodiment, the order of the area divided by the solid line, the area divided by the dashed-dotted line, and the area divided by the dotted line may be changed. For example, after the determination of the area divided by the dotted line in the first crystal boundary form of FIG. 24, the area divided by the solid line (one rotation) and the dashed-dotted line (two rotations) may be determined according to the rotation. have.

Likewise, in the examples of FIGS. 23 and 24, the rotation is performed by 60 degrees. However, depending on the embodiment, the rotation may be rotated by -60 degrees.

25 is a block diagram schematically showing another signal transmission apparatus according to an embodiment of the present invention. The signal transmission apparatus of FIG. 25 is an example of using a multiple mapping scheme for the signal transmission apparatus of FIG. 1.

The embodiment of FIG. 25 includes an outer encoder 2500, an inner encoder 2510, a first interleaver 2520, a multiple mapper 2530, a linear precoding unit ( 2540, a second interleaver 2550, a frame builder 2560, a modulator 2570, and a transmitter 2580. An outer interleaver may be added between the outer encoder 2500 and the inner encoder 2510, and a multiple input / output encoder may be added between the second interleaver 2550 and the frame forming unit 2560, according to an embodiment. have.

The outer encoder 2500 and the inner encoder 2510 encode and output the input signal, respectively, so that an error occurring in the transmitted data can be detected by the receiver and the error can be corrected. That is, the outer encoder 2500 and the inner encoder 2510 may be regarded as a forward error correcting encoder (FEC). The type of each encoder may vary according to a coding scheme used in a corresponding signal transmission system.

The first interleaver 2520 distributes the data sequence to a random position so as to be robust to a burst error that may occur when the signal output from the inner encoder 2510 is transmitted. For example, a block interleaving method or a convolution interleaving method may be used for the first interleaver 2520. The type of the first interleaver 2520 may vary depending on the method used in the corresponding signal transmission system.

The multiple mapper 2530 maps the data interleaved in the first interleaver 2520 into symbols according to a transmission scheme. The multiple mapper 2530 mixes a plurality of mapping methods to map input data to symbol data. Quadrature Amplitude Modulation (QAM), Quadrature Phase Shift Keying (QPSK), Amplitude Phase Shift Keying (APSK), Pulse Amplitude Modulation (PAM), and Optimal Constellation may be used as the mapping scheme.

Using the multiple mapping scheme as described above, a signal to noise ratio (SNR) gain can be obtained from the method of mapping to a small constellation size, and the rate gain (from a method of mapping to a large constellation size) can be obtained. capacity gain) can be obtained. Therefore, the gain between the SNR and the transmission rate can be adjusted by adjusting the mixing ratio of the mapping scheme, and the transmission efficiency can be improved.

26 is a block diagram schematically illustrating a multiple mapper according to an embodiment of the present invention. The multiple mapper 2530 includes a bit stream distributor 2253, a first mapper 2532, a second mapper 2533,. , An N-th mapper 2534, and a symbol interleaver 2535.

The bit stream distributor 2253 distributes the input bit data to a plurality of mappers. The bit stream distributor 2253 distributes the required number of bit data for mapping to symbols according to the mapping method of each mapper.

27 illustrates a bit stream distribution scheme according to an embodiment of the present invention. That is, the bit stream distribution method represents an example of a method of distributing a bit stream in the bit stream distribution unit 2531.

In the bit stream distribution method of FIG. 27, input bit data is stored in a matrix-type storage space in a predetermined pattern, and data is read and output in a pattern different from the storage pattern. In this case, the effect of a kind of virtual interleaver can be obtained.

For convenience of explanation, it is assumed that the number of mappers for distributing input bit data is two. For example, when the length of one block input to the bit stream distribution unit 2253 is M × N bits, the block is divided into M equal parts and filled in the storage space from one row to one row. Data is stored starting from row 1 of column 1 up to row M, and when the column 1 is filled up, data is stored starting from row 1 of the next column (column 2) up to row M. Data can be stored up to M rows of N columns in the above order. In this case, the MSB (Most Significant Bit) position of the storage space is at the top left, and the LSB (Least Significant Bit) position is at the bottom right.

In the two mappers, when the bit ratio of the symbols of the first and second mappers is M-R: M, the data stored in the storage space is divided into M-R rows and R rows, respectively. The divided bit data is output in a row manner. In other words, starting from the data of 1 row and 1 column, reading the data of the row up to 1 row N column, and reading all the data of the row, starting from the 1 column of the next lower row (row 2) to the right direction Read and output the data. In the same order as above, the data is read up to the M-R line and output to the first mapper. The data of the remaining R rows is also read in the row direction and output to the second mapper.

In the above embodiment, the size of the block, the storage pattern, the read pattern, and the like are one embodiment, which may vary depending on the embodiment. For example, it is also possible to distribute the input bit data to each mapper in the input order.

The bit data distributed by the bit stream distributor 2253 is output to each mapper (first mapper 2532 to N-th mapper 2534). The first mapper 2532 to the N-th mapper 2534 may be viewed as a mapping unit that maps the input bit data into symbol data. Each mapper maps the input bit data into symbol data according to a corresponding mapping scheme. QAM, QPSK, APSK, PAM, optimal constellation, etc. may be used as the mapping scheme.

Each of the mappers (the first mapper 2532 to the N-th mapper 2534) may use the same type of mapping scheme, and may vary the number of bit data included in one symbol, and different types of mapping for each mapper. You can also use the method. For example, while the first mapper 2532 to the N-th mapper 2534 use the QAM method, the first mapper 2532 is 16QAM, the second mapper 2533 is 64QAM, and the N-th mapper 2534 is 256QAM. Symbol mapping. Alternatively, the first mapper 2532 may map in a QAM scheme, and the N-th mapper 2534 may map in an optical constellation scheme. The example may vary depending on the implementation.

Each mapper (the first mapper 2532 to the N-th mapper 2534) performs symbol mapping on the input data and outputs the data according to a predetermined mapping method.

The symbol interleaver 2535 interleaves the symbol data output from the mappers, sorts them into one symbol string, and outputs the result. Bit-reversed addressing, in which the block interleaving method, the convolutional interleaving method, or the symbols are designated as one block, and then the addresses corresponding to the order of the blocks are output in the order of bit inversion. ) May be used for interleaving. Alternatively, the symbol data output from the respective mappers may be simply arranged in a predetermined order and output without interleaving the symbols. This may vary depending on implementation.

The linear precoding unit 2540 distributes the input symbol data into a plurality of output symbol data to reduce the probability that all information is lost due to fading when subjected to a frequency selective fading channel. The linear precoding unit 2540 may not be used depending on implementation.

The second interleaver 2550 interleaves the symbol data output from the linear precoding unit 2540 again so that the symbol data does not experience the same frequency selective fading. The second interleaver 2550 may use a block interleaving method or a convolutional interleaving method.

The frame forming unit 2560 forms a frame by inserting a pilot signal in a data section so that the interleaved signal can be modulated by an orthogonal frequency division multiplex (OFDM) scheme. The modulator 2570 inserts a guard interval to modulate the data output from the frame forming unit 2560 on subcarriers of OFDM. The transmitter 2580 converts a digital signal having a guard period and a data period output from the modulator 2570 into an analog signal and transmits the signal.

28 is a block diagram schematically illustrating an apparatus for receiving a signal according to an embodiment of the present invention. The embodiment of FIG. 28 is an example of a case where a multiple mapping scheme is used for the signal receiving apparatus of FIG. 9 as a receiving apparatus corresponding to the transmitting apparatus of FIG. 25.

An embodiment according to the present invention of FIG. 28 includes a receiver 2800, a synchronizer 2810, a demodulator 2820, a frame parsing unit 2830, a first deinterleaver 2840, and a linear free. A coding decoder 2850, a multiple demapper 2860, a second deinterleaver 2870, an inner decoder 2880 and an outer decoder 2890 are included. According to an embodiment, an outer deinterleaver may be added between the inner decoder 2880 and the outer decoder 2890, and a multiple input / output decoder may be added between the frame parser 2830 and the first deinterleaver 2840. May be

The receiver 2800 down-converts the frequency band of the received RF signal and converts the frequency band into a digital signal. The synchronizer 2810 obtains and outputs a synchronization between a frequency domain and a time domain of the received signal output from the receiver 2800. The synchronization unit 2810 may use an offset result of the frequency domain of data output by the demodulator 2820 to obtain synchronization of the frequency domain signal.

The demodulator 2820 demodulates the received data output from the synchronizer 2810 and removes a guard interval. To this end, the demodulator 2820 converts the received data into the frequency domain, and decodes the data values distributed in the subcarriers into values assigned to each subcarrier. The frame parser 2830 may output symbol data of a data symbol period excluding pilot symbols according to the frame structure of the signal demodulated by the demodulator 2820.

The first deinterleaver 2840 performs de-interleaving on the data string output from the frame parser 2830 to restore the data in the order before interleaving. The first deinterleaver 2840 deinterleaves the data sequence by deinterleaving according to a method corresponding to the interleaving method of the second interleaver 2550 of FIG. 25.

The linear precoding decoder 2850 performs an inverse process of distributing data in the signal transmission apparatus, thereby restoring original data dispersed in the data input to the linear precoding decoder 2850. The linear precoding decoder 2850 is used only when the linear side has undergone a linear precoding process.

The multiple demapper 2860 may recover the symbol data recovered by the linear precoding decoder 2850 into a bit string. The demapping method of the multiple demapper 2860 uses a method corresponding to the mapping method used in the multiple mapper 2530 of the transmitting apparatus as illustrated in FIG. 25.

29 is a block diagram schematically illustrating multiple demappers according to an embodiment of the present invention. The multiple demapper 2860 includes a symbol deinterleaver 2861, a first demapper 2862, a second demapper 2863,. , An N-th demapper 2864, and a bit stream recovery unit 2865.

The symbol deinterleaver 2861 deinterleaves the input symbol data to restore the original symbol data order. The deinterleaving method of the deinterleaver 2861 uses a method corresponding to a method in which the symbol interleaver 2535 interleaves in the multiple mapper 2530 of FIG. 26. The symbol deinterleaver 2861 transmits the deinterleaved symbol data to a demapper corresponding to the mapped scheme.

Each demapper (first demapper 2862 to N-th demapper 2864) converts the received symbol data into bit data according to a corresponding demapping scheme. The first demapper 2862 to the N-th demapper 2864 may be viewed as a demapping unit for demapping input symbol data into bit data. The demapping schemes of the first demapper 2862 to the N-th demapper 2864 correspond to the mapping methods of the first mapper 2532 to the N-th mapper 2534 of FIG. 26.

The bit stream recovery unit 2865 receives bit data output from each demapper and outputs one bit stream. The bit stream recovery unit 2865 restores the bit stream using a method corresponding to the method distributed by the bit stream distribution unit 2253 of FIG. 26.

The second deinterleaver 2870 performs an inverse process of interleaving on the bit data string demapped by the multiple demapper 2860. The second deinterleaver 2870 performs deinterleaving corresponding to the first interleaver 2520 of FIG. 25. An inner decoder 2880 may correct the error included in the data by decoding the deinterleaved data. The outer decoder 2890 performs an error correction decoding process on the bit data decoded by the inner decoder 2880 and outputs the same. The inner decoder 2880 and the outer decoder 2890 decode data according to decoding methods corresponding to the inner encoder 2510 and the outer encoder 2500 of FIG. 25, respectively.

30 is a block diagram schematically illustrating an apparatus for transmitting a signal using multiple encodings according to an embodiment of the present invention. The signal transmission apparatus of FIG. 30 is an example of using a multiple encoding scheme for the signal transmission apparatus of FIG. 1.

 30 illustrates an outer encoder 3000, a multiple encoder 3010, a first interleaver 3020, a symbol mapper 3030, a linear precoding unit 3040, a second interleaver 3050, A frame builder 3060, a modulator 3070, and a transmitter 3080 are included. In addition, an outer interleaver and a multiple input / output encoder may be added according to an embodiment.

The outer encoder 3000 and the multiple encoder 3010 encode and output the input signals, respectively, so that an error occurring in the transmitted data can be detected by the receiver and the error can be corrected. The outer encoder 3000 encodes input data to improve transmission performance for the input signal. The type of encoder may vary depending on the coding scheme used in the corresponding signal transmission system.

The multiple encoder 3010 re-encodes the data encoded by the outer encoder 3000 in preparation for an error that may occur in the transmission process. The multiple encoder 3010 encodes the input data by mixing a plurality of encoding schemes. For example, convolutional coding, Reed-Solomon (RS) coding, low density parity check (LDPC) coding, turbo coding, and the like may be used as the encoding scheme.

By using the multiple encoding scheme as described above, a signal to noise ratio (SNR) gain can be obtained from an encoding scheme having a low code rate, and a transmission rate can be obtained from an encoding scheme having a high code rate. Gain can be obtained. Therefore, by adjusting the mixing ratio of the encoding scheme, it is possible to adjust the gain between the SNR and the transmission rate, and increase the transmission efficiency.

31 is a block diagram schematically illustrating a multiple encoder according to an embodiment of the present invention. The multiple encoder 3010 includes a bit stream distributor 3011, a first encoder 3012, a second encoder 3013,. , An Nth encoder 3014, and a bit stream recovery unit 3015.

The bit stream distributor 3011 distributes the input bit data to a plurality of encoders. The bit stream distributor 3011 distributes the required number of bit data according to the encoding scheme of each encoder. The bit stream distribution unit 3011 may distribute the input bit data according to the bit stream distribution scheme as shown in FIG. 27, or may distribute the input bit data to each mapper in the order in which the input bit data is input. Such a distribution scheme may vary depending on implementation.

The bit data distributed by the bit stream distributor 3011 is output to each encoder (the first encoder 3012 to the Nth encoder 3014). The first encoder 3012 to the Nth encoder 3014 may be regarded as an encoding unit for encoding and outputting input bit data. Each encoder encodes input bit data according to the corresponding encoding scheme. For example, convolutional coding, Reed-Solomon (RS) coding, low density parity check (LDPC) coding, turbo coding, and the like may be used as the encoding scheme.

Each of the encoders (the first encoder 3012 to the Nth encoder 3014) may use a different encoding rate while using the same type of encoding scheme, or may use a different type of encoding scheme for each encoder. For example, while the first encoder 3012 to the Nth encoder 3014 both use the LDPC method, the code rate of each mapper can be changed. Alternatively, the first encoder 3012 may encode the LDPC method, and the N-th mapper 3014 may encode the turbo coding method. The example may vary depending on the embodiment.

The bit stream recovery unit 3015 receives the bit data output from the respective encoders, and recovers the bit data into one bit data string. The bit stream recovery unit 3015 may restore the reverse of the distribution method of the bit stream distribution unit 3015, or may restore the data to one bit data string according to another predetermined rule. This may vary depending on implementation, and a virtual interleaving effect may be obtained according to the restoration method.

The first interleaver 3020 distributes the data sequence to a random position so as to be robust to a burst error that may occur when the signal output from the multiple encoder 3010 is transmitted. The symbol mapper 3030 maps bit data received from the first interleaver 3020 into symbol data. Alternatively, an encoded symbol mapping method may be used for the symbol mapper 3030. For example, it may be mapped to a coded symbol using a method such as trellis code modulation.

The linear precoding unit 3040 distributes the input symbol data into a plurality of output symbol data to reduce the probability that all information is lost due to fading when subjected to a frequency selective fading channel. The linear precoding unit 3040 may not be used depending on implementation.

The second interleaver 3050 interleaves the symbol data output from the linear precoding unit 3040 again so that the symbol data does not experience the same frequency selective fading. The second interleaver 3050 may use a block interleaving method or a convolutional interleaving method.

The frame forming unit 3060 forms a frame by inserting a pilot in the data section so that the interleaved signal can be modulated by an orthogonal frequency division multiplex (OFDM) scheme. The modulator 3070 inserts and modulates a guard interval so that the data output from the frame forming unit 3060 can be carried on each subcarrier of OFDM. The transmitter 2080 converts a digital signal having a guard interval and a data interval output from the modulator 2070 into an analog signal and transmits the signal.

32 is a block diagram schematically showing a signal receiving apparatus for receiving a multi-encoded signal according to an embodiment of the present invention. The receiver of FIG. 32 represents a receiver corresponding to the transmitter of FIG. 30.

The embodiment according to the present invention of FIG. 32 includes a receiver 3200, a synchronizer 3210, a demodulator 3220, a frame parsing unit 3230, a first deinterleaver 3240, and a linear free. A coding decoder 3250, a symbol demapper 3260, a second deinterleaver 3270, a multiple decoder 3280, and an outer decoder 3290 are included.

The receiver of FIG. 32 is the same as that described with reference to FIG. 28. Hereinafter, different parts from FIG. 28 will be described.

The trellis code decoder 3260 may restore the symbol data reconstructed by the linear precoding decoder 3250 into a bit string. The symbol demapper 3260 demaps symbol data using a method corresponding to the method mapped by the symbol mapper 3030 of FIG. 30.

The multiple decoder 3280 receives the deinterleaved bit data from the second deinterleaver 3270 and decodes the bits according to a method encoded by the transmitter.

33 is a block diagram schematically illustrating multiple decoders according to an embodiment of the present invention. The multiple decoder 3280 may include a bit stream distribution unit 3331, a first decoder 3302, a second decoder 3283,. , An N-th decoder 3284, and a bit stream recovery unit 3285.

The bit stream distribution unit 3331 distributes the input bit data to a plurality of decoders. The bit stream distribution unit 3231 distributes bit data in a manner corresponding to a method in which the bit stream recovery unit 3015 reconstructs one bit data string in the multiple encoder of FIG. 31. That is, the bit stream recovery unit 3015 of the multiple encoder receives the bit data and distributes the bit data as opposed to the method of forming the bit data string.

The bit data distributed by the bit stream distribution unit 3331 is output to each decoder (first decoder 3302 to Nth decoder 3284). The first decoders 3328 to N-th decoders 3284 may be viewed as a decoding unit for decoding and outputting input bit data. Each decoder encodes the input bit data according to the corresponding decoding scheme. The decoding method uses a method corresponding to the method encoded by the multiple encoder of FIG. 31.

The bit stream recovery unit 3285 receives the bit data output from the respective decoders, and recovers the bit data into one bit data string. The bit stream recovery unit 3285 restores the order in the inverse of the manner in which the bit data distribution unit 3011 distributes the bit data.

An outer decoder 3290 performs an error correction decoding process on the bit data decoded by the multiple decoder 3280 and outputs the same. That is, the multiple decoder 3280 and the outer decoder 3290 decode data according to decoding methods corresponding to the multiple encoder 3010 and the outer encoder 3000 of FIG. 30, respectively.

34 is a block diagram schematically illustrating an apparatus for transmitting a signal using multiple encoding and multiple mapping according to an embodiment of the present invention. As shown in FIG. 34, a signal transmission apparatus may be implemented using both the multiple encoding scheme and the multiple mapping scheme described with reference to FIGS. 25 and 30.

The signal transmission apparatus includes an outer encoder 3400, a multiple encoder 3410, a first interleaver 3420, a multiple mapper 3430, a linear precoding unit 3440, a second interleaver 3450, and a frame forming unit ( 3460, a modulator 3470, and a transmitter 3480, and the description of each block is the same as described with reference to FIGS. 25 and 30, respectively.

35 is a block diagram schematically illustrating a signal receiving apparatus for receiving multiple encoding and multiple mapped signals according to an embodiment of the present invention. The signal receiving apparatus of FIG. 35 corresponds to the signal transmitting apparatus of FIG. 34, and includes a receiver 3500, a synchronizer 3510, a demodulator 3520, a frame parsing unit 3530, and a first device. An interleaver 3540, a linear precoding decoder 3550, a multiple demapper 3560, a second deinterleaver 3570, a multiple decoder 3580, and an outer decoder 3590. Likewise, the description of each block of the signal receiving apparatus is the same as those described with reference to FIGS. 28 and 32, respectively.

36 is a block diagram schematically illustrating another signal receiving apparatus for receiving multiple encoding and multiple mapped signals according to an embodiment of the present invention. The signal receiving apparatus includes a receiver 3600, a synchronizer 3610, a demodulator 3620, a frame parser 3630, a first deinterleaver 3640, an equalizer 3650. ), A linear precoding decoder 3660, a multiple demapper 3670, a channel estimator 3680, a second deinterleaver 3690, a multiple decoder 3692, and an outer decoder 3694. .

In a system to which the multiple mapping scheme is applied, a symbol having a small constellation size has a relatively low minimum required SNR compared to a symbol having a large constellation size. Therefore, in order to further increase the capacity, a symbol having a small constellation size may be used as a pilot symbol. That is, by not using a separate pilot or by performing a function of some pilots using a symbol having a small constellation size, the transmission rate is increased by the number of pilots reduced. In the case of using the symbol having the small constellation size, the channel is estimated based on the value determined by receiving the symbol.

The minimum required SNR of the symbol with the large constellation size is higher than the minimum required SNR of the symbol with the relatively small constellation size. Therefore, in an SNR section in which a symbol having a large constellation size is decoded, reliability of a symbol having a small constellation size is relatively high and thus can be used as a pilot symbol.

The division of the symbol having the small constellation size and the symbol having the large constellation size may vary depending on the implementation of the implementer. For example, in the case where a specific constellation point or more is divided into a large constellation size, the number of reference points may vary depending on implementation.

When multiple mapping is performed on the symbol data having a small constellation size and the symbol data having a large constellation size as described above, the signal transmission apparatus may insert and transmit a pilot to the multi-mapped symbol data. As described above, when symbol data having a small constellation size is used as a pilot symbol, the signal transmission apparatus may insert and transmit the symbol data having the small constellation size instead of a pilot at an insertion position of the pilot.

When the symbol data having the small constellation size is inserted into a pilot insertion position, symbol data having the small constellation size may be inserted into all of the pilot insertion positions, and symbol data having the small constellation size may be inserted only at a part of the positions. You can also insert the pilot in the rest position.

For example, in the signal transmission apparatus as shown in FIG. 34, the frame forming unit 3460 may form a frame by inserting symbol data having a small constellation size for all pilot insertion positions. Alternatively, the frame forming unit 3460 may insert a symbol data having a small constellation size in only a part of the position and insert a pilot in the other position to form a frame. In consideration of the channel situation, the transmission and reception system, etc., an appropriate method may be selected and implemented.

In the case of FIG. 34, a multiple encoding scheme is also used. However, the present invention may also be applicable to a case of encoding with a general inner encoding scheme instead of the multiple encoding scheme.

36 is a diagram illustrating an apparatus for receiving and processing a signal when a signal is transmitted using symbol data having a small size as a pilot symbol in the signal transmission apparatus as shown in FIG. 34.

Hereinafter, for convenience of description, a description will be given of parts of the block of FIG. 36 that do not overlap with the block of FIG. 35.

The frame parser 3630 parses the frame data demodulated by the demodulator 3620. When the frame is formed by inserting symbol data having a small constellation size for all pilot insertion positions in the signal transmission apparatus as described above, the frame parsing unit 3630 extracts the symbol data inserted at the pilot positions to extract the remaining symbols. Restore with the data. If, in the signal transmission apparatus, symbol data having a small constellation size is inserted only at a portion of pilot insertion positions, and a pilot is inserted at the remaining positions, the frame parsing unit 3630 may use the small constellation size. The pilot data is extracted together with the symbol data having a to recover the symbol data.

For convenience of explanation, the following description will focus on a case in which symbol data having a small constellation size is inserted in only some of the pilot insertion positions and a pilot is inserted in the remaining positions.

The channel estimator 3680 estimates a transmission channel using the pilot output from the frame parser 3630 and input / output information of the multiple demapper 3670. When estimating a channel using the pilot output from the frame parsing unit 3630, a pilot received on a k-th carrier is referred to as P _r (k), and a promised pilot known to the receiver is referred to as P _{r. In the case of t} (k), a channel transfer function (CTF) is represented by Equation 2 below.

H _p (k) refers to a channel transfer function estimated using a pilot.

In addition, when estimating a channel using symbol data having a small constellation size inserted at a pilot insertion position, the received symbol data, that is, symbol data input to the multiple demapper 3670 is referred to as Y _r (k). When the determined symbol data, that is, symbol data output from the multiple demapper 3670 is referred to as Y _t (k), the channel transfer function is expressed by Equation 3 below.

The H _d (k) refers to a channel transfer function estimated using symbol data having a small constellation size. The division operation may be performed by directly designing a divider, or may be performed by calculating the inverse of the denominator or multiplying by a numerator. Alternatively, the multiplication may be performed by referring to a ROM table that stores the reciprocal value of the denominator. Alternatively, the reciprocal value of the denominator multiplied by the complex conjugate of the denominator and the numerator complex number are multiplied, respectively, to obtain a reciprocal value of the denominator multiplied by the complex complex number. It can also be done by multiplying by. This may vary depending on implementation.

When no pilot symbol is used in the signal transmission apparatus, only a channel transfer function using symbol data having a small constellation size can be obtained as shown in Equation 3 above.

The channel transfer function estimated in Equation 2 or 3 may be used for channel equalization. The receiver may equalize a channel by selecting one value among the estimated values, or equalize by interpolating the two estimated values. For example, the selection method may vary depending on the implementation, such as selecting one value in consideration of a channel condition, or selecting and using a different estimated value when a specific estimated value changes abruptly. Alternatively, the estimated two values may be equalized to values obtained by interpolation through linear interpolation or the like.

37 is a block diagram schematically illustrating a channel estimator in accordance with an embodiment of the present invention. The channel estimator includes a determiner 3700, a first calculator 3710, a first multiplier 3720, a second multiplier 3730, a second calculator 3740, a pilot generator 3750, and a third calculator. 3760, a third multiplication unit 3770, a fourth multiplication unit 3780, and a fourth operation unit 3790. If a pilot symbol is not inserted, the pilot generator 3750, the third operator 3760, the third multiplier 3770, the fourth multiplier 3780, and the fourth operation are used. Part 3790 is not used.

The channel estimator of FIG. 37 multiplies the denominator and the numerator by the complex conjugate value of the denominator to obtain the inverse value of the denominator multiplied by the conjugate complex number. This is an example of obtaining a channel transfer function by multiplying by.

First, pilot symbol data (symbol data having a small constellation size in this example) input to the symbol demapper 3670 and pilot symbol data output from the symbol demapper 3670 are input to the determining unit 3700. . The determiner 3700 outputs the symbol data output from the symbol demapper 3670 to the first operator 3710 and the first multiplier 3720.

The first operator 3710 obtains a complex conjugate value of the input symbol data and outputs the complex conjugate value to the first multiplier 3720 and the second multiplier 3730. The first multiplier 3720 multiplies the symbol data output from the determiner 3700 and the conjugate complex value output from the first operator 3710 and outputs the multiplied complex value to the second operator 3740. The second multiplier 3730 may multiply the symbol data input to the symbol demapper 3670 among the symbol data input to the determiner 3700 and the conjugate complex value output from the first operator 3710 to obtain a second operator ( 3740).

The second calculator 3740 obtains an inverse value corresponding to the value output from the first multiplier 3720, and multiplies the inverse value by the value output from the second multiplier 3730.

When estimating the channel transfer function using the pilot symbols, the pilot symbols extracted by the frame parser 3630 are used. The pilot generator 3750 generates a pilot symbol previously promised with the transmitting side. The generated pilot symbols are output to the third operator 3760 and the third multiplier 3770.

The third operation unit 3760 obtains a complex conjugate value of the input pilot symbol and outputs the complex conjugate value to the third multiplier 3770 and the fourth multiplier 3780. The third multiplier 3770 multiplies the pilot symbol output from the pilot generator 3750 and the conjugate complex value output from the third operator 3760 and outputs the multiplied complex value to the fourth operator 3790. The fourth multiplier 3780 multiplies the pilot symbol extracted by the frame parser 3630 and the conjugate complex value output from the third operator 3760 and outputs the multiplied complex value to the fourth operator 3790.

The fourth calculator 3790 obtains an inverse value corresponding to the value output from the third multiplier 3770, and multiplies the inverse value by the value output from the fourth multiplier 3780.

The first deinterleaver 3640 deinterleaves the symbol data output from the frame parser 3630 to restore the order. The deinterleaved data is output to the equalizer 3650. The equalizer 3650 compensates for the distortion due to the transmission channel with respect to the reconstructed symbol data by using a channel transfer function for the channel estimated by the channel estimator 3680.

For example, the equalizer 3650 may use a zero forcing equalization scheme to compensate for the channel distortion. Since the received symbol can be represented as a product of the transmission symbol and the channel transmission function, dividing the received symbol by the estimated channel transmission function can restore the transmission symbol data value. That is, if the received symbol data value is Yr (k) and the estimated channel transfer function is H (k), the recovered symbol data value Y _eq (k) is expressed by Equation 4.

38 is a block diagram schematically illustrating an equalizer according to an embodiment of the present invention. The equalizer 3650 includes an interpolator 3800, a fifth operator 3810, a fifth multiplier 3820, a sixth multiplier 3830, and a sixth operator 3840. The equalizer of FIG. 38 is an example of implementing the zero forcing equalization scheme as described above.

There are various methods for performing the division operation as described above, but the equalizer of FIG. 38 uses the same process as that of performing the division operation of FIG. 37.

The interpolator 3800 interpolates the input channel transfer function value to a value of full bandwidth. The channel transfer function values interpolated by the interpolator 3800 are output to the fifth operator 3810 and the fifth multiplier 3820. The fifth operator 3810 calculates and outputs a complex conjugate value of the channel transfer function output from the interpolator 3800.

The fifth multiplier 3820 multiplies the channel transfer function value output from the interpolator 3800 and the conjugate complex value of the channel transfer function output from the fifth operator 3810 to the sixth operator 3840. Output The sixth multiplier 3830 multiplies the conjugate complex value output from the fifth operator 3810 by the received symbol data and outputs the multiplied complex value to the sixth operator 3840.

The sixth operator 3840 obtains an inverse value corresponding to the value output from the fifth multiplier 3820, and multiplies the inverse value by the value output from the sixth multiplier 3830.

The symbol data equalized by the equalizer 3650 is output to the linear precoding decoder 3660. The linear precoding decoder 3660 reconstructs and outputs distributed symbol data, and the reconstructed symbol data is input to the multiple demapper 3670 and the channel estimator 3680.

The multiple demapper 3670 demaps the received symbol data using each demapper and outputs corresponding bit data. The multiple demapper 3670 transmits the symbol data value determined for the symbol data having a small constellation size to the channel estimator 3680. Alternatively, the demapped bit data of the symbol data having the small constellation size may be output to the channel estimator 3680. Since the channel is estimated in the unit of symbol data, when outputting the demapped bit data for symbol data having a small constellation size to the channel estimator 3680, the determiner 3700 of FIG. The symbol data corresponding to the received bit data must be determined again.

The second deinterleaver 3690 recovers the order by deinterleaving the bit data received by the multiple demapper 3670. The multiple decoder 3692 multiplexes and outputs the reconstructed bit data according to a multi-encoded scheme. If a signal transmission apparatus does not use multiple encoding schemes but uses one encoding scheme, multiple decoders are not used and one decoding scheme corresponding to the encoding scheme is used.

39 is a block diagram schematically illustrating a signal transmission apparatus of a data symbol channel estimation method according to an embodiment of the present invention. The signal transmitting apparatus includes an outer encoder 3900, an inner encoder 3910, a first interleaver 3920, a symbol mapper 3930, a linear precoding unit 3940, a second interleaver 3950, and a frame forming unit 3960. ), A modulator 3970, and a transmitter 3980.

As described above, when the symbol data having the small constellation size is inserted in all the insertion positions of the pilot, or the symbol data having the small constellation size is inserted in only a partial position, and the pilot is inserted in the remaining positions, the pilot insertion is performed. The symbol data inserted at the position may be determined, and a channel may be estimated based on the determined symbol data. In the case of the above scheme, channel estimation performance can be increased, and the entire system can be increased by not using pilot symbols or using only a part of the pilot symbols.

However, if a decision error occurs in a low SNR environment, an error may occur in the channel estimation, and an error of data compensated with the channel estimation value having the error may become larger, resulting in error propagation. Symptoms may occur.

In order to prevent the error spreading phenomenon, the channel is estimated using only a decision value having high reliability among decision values of the received symbol data.

For example, it is assumed that the symbol data having the small constellation size is inserted into all of the pilot insertion positions in the signal transmission apparatus as shown in FIG. Each block of the signal transmission apparatus of FIG. 39 and the signal transmission apparatus of FIG. 34 is the same, except that a different symbol mapping scheme is used instead of the multiple mapping scheme. For example, a symbol mapping method such as QAM, QPSK, optical constellation method, or the like may be used, or trellis code modulation may be used as an encoded symbol mapping method. The description of the signal transmission device of FIG. 39 is the same as that of FIG. 34.

However, the frame forming unit 3960 of FIG. 39 inserts the symbol data having the small constellation size at the pilot insertion position without inserting the pilot, and thus extracts the remaining symbol data by extracting the symbol data inserted at the pilot insertion position. Restore with

40 is a block diagram schematically illustrating a signal receiving apparatus of a data symbol channel estimation method according to an embodiment of the present invention. The signal receiver includes a receiver 4000, a synchronizer 4002, a demodulator 4004, a frame parsing unit 4008, a first deinterleaver 4010, and an equalizer 4012. ), Linear precoding decoder 4014, symbol demapper 4016, channel state estimator 4018, channel estimator 4020, second deinterleaver 4022, inner decoder 4024 and an outer decoder 4026. The signal receiving device of FIG. 40 receives and processes a signal transmitted from the signal transmitting device of FIG. 39.

The signal receiving apparatus of FIG. 40 corresponds to the signal receiving apparatus of FIG. 36, and a description of common parts will be omitted for convenience of description.

Since the pilot is not inserted into the received frame data and the symbol data having the small constellation size is inserted at the pilot insertion position, the frame parsing unit 4008 of FIG. 40 uses the symbol data inserted at the pilot insertion position. Extract and restore with the rest of the symbol data.

The channel state estimator 4018 estimates the position of each symbol data, that is, the state of a transmission channel for each subcarrier. In order to estimate the channel state, a Log-Likelihood Ratio (LLR) value used for symbol data determination or an SNR of a channel may be used. The subcarrier for estimating the channel state may be a subcarrier for transmitting symbol data inserted at the pilot insertion position, or may be a subcarrier for transmitting other symbol data included in a frame.

The channel estimator 4020 determines a channel having a good state by using the state of each channel estimated by the channel state estimator 4018, and estimates a channel by using symbol data received from the channel having a good state. . For example, the good channel may be a case in which the SNR of the channel is high or the LLR value is high. In addition, if a high reliability is applied to a channel that receives symbol data having a small constellation size or symbol data coded at a low code rate in addition to the above information, the channel estimation error can be further reduced.

The channel estimator 4020 may obtain a channel estimation function by using the received symbol data for the good channel and the symbol data determined by the symbol demapper 4016. The equalizer 4012 compensates for the channel distortion of the received symbol data by using the channel estimation function output from the channel estimator 4020.

In addition to the method of estimating the channel using the determined symbol data described above, a multiple encoding scheme or a multiple mapping scheme may be used. That is, the multiple encoding scheme and the multiple mapping scheme may be separately used together or may be applied to the scheme of estimating the channel using the determined symbol data.

FIG. 41 is a block diagram schematically illustrating another signal transmission apparatus of a data symbol channel estimation method according to an embodiment of the present invention, and FIG. 42 is another signal of the data symbol channel estimation method according to an embodiment of the present invention. A block diagram schematically showing a receiving device.

The signal transmission apparatus of FIG. 41 includes an outer encoder 4100, a multiple encoder 4110, a first interleaver 4120, a multiple mapper 4130, a linear precoding unit 4140, a second interleaver 4150, and frame formation. And a signal receiver 4160, a modulator 4170, and a transmitter 4180. The signal receiver of FIG. 42 includes a receiver 4200, a synchronizer 4202, a demodulator 4204, A frame parsing section 4206, a first deinterleaver 4208, an equalizer 4210, a linear precoding decoder 4212, a multiple demapper 4214, a channel state ) An estimator 4216, a channel estimator 4218, a second deinterleaver 4220, a multiple decoder 4222, and an outer decoder 4224.

41 and 42 are examples of using both a multiple encoding scheme and a multiple mapping scheme in a method of estimating a channel using the determined symbol data, and the description of each block is the same as described in the above embodiments.

In the exemplary embodiments described with reference to FIGS. 25 to 42, transmission and reception may be performed using a multi input multi output (MIMO) scheme as shown in FIG. 1 or 9. In the case of using the multiple input / output method as described above, a multiple input / output encoder is added between the interleaver and the frame forming unit at the transmitting side, and a multiple input / output decoder is added between the frame parsing unit and the deinterleaver at the receiving side.

43 is a diagram showing the structure of a transport frame according to an embodiment according to the present invention. The frame forming unit of the transmitting apparatus described in the above embodiments may form and output transmission frame data having the structure as shown in FIG. 43.

The transmission frame of FIG. 43 includes a pilot symbol period including pilot carrier information, and a data symbol period including data information and tracking pilot information. The transmission frame of FIG. 43 is an embodiment in which a pilot signal is inserted (or mapped) in a data symbol period among the transmission frames of FIG.

When transmitting a frame having the structure as shown in FIG. 43, the receiving side performs channel estimation on the frame using pilot carrier information located in the pilot symbol period. However, when the channel state changes, it is difficult for the receiving side to accurately estimate the channel only with the pilot carrier information located in the pilot symbol interval. Therefore, in addition to the pilot carrier information located in the pilot symbol interval, the channel pilot for the interval in which the tracking pilot is included can be accurately used using the tracking pilot included in the data symbol interval. The tracking pilot may be inserted in the form of a scattered pilot as shown in FIG. 45.

FIG. 44 is a diagram illustrating the number of tracking pilots according to a frame according to an embodiment of the present invention. FIG. In the OFDM method, a symbol may be transmitted on each subcarrier by using a Fourier transform.

FIG. 44 illustrates the number of usable subcarriers, the number of tracking pilots, and the number of symbol data according to the FFT mode when a symbol is transmitted using a Fast Fourier Transform (FFT). The number of usable subcarriers indicates the total number of subcarriers minus the number of subcarriers for TPS (Transmission Parameter Signaling) and the like, and the number of tracking pilots indicates the number of tracking pilots inserted in the data symbol interval. . The number of symbol data indicates the number of subcarriers that can transmit symbol data by subtracting the number of tracking pilots from the number of usable subcarriers. For example, in the 2k mode, 68 out of 1688 usable subcarriers are used to transmit tracking pilots, and the remaining 1620 subcarriers are used to transmit symbol data.

45 is a view illustrating a frame including a tracking pilot according to an embodiment of the present invention. 45 illustrates a form in which a tracking pilot is inserted in one data symbol period according to a 2k mode among the transmission modes of FIG. 44.

That is, in FIG. 45, 68 subcarriers are used to transmit tracking pilot information among 1688 subcarriers except for the TPS in 1710 subcarriers (0th to 1709th). Indicates that a subcarrier is used to transmit symbol data.

In this example, the tracking pilot has five patterns (patterns 0 to 4) and is inserted in the form of a scattered pilot. The symbol distance between one pattern and the tracking pilot of the next pattern is 5, and the symbol distance between the tracking pilots in one pattern is 25.

FIG. 46 is a view illustrating a margin along the frame of FIG. 45 according to an embodiment of the present invention. FIG. When the tracking pilot is inserted in the form as shown in FIG. 45, margins are generated by 4 symbol distances and 5 symbol distances from side to side, respectively. Since the channel estimation cannot be tracked in the region where the margin occurs, the margin should be reduced for accurate channel estimation.

FIG. 46 shows the number of tracking pilots and the number of distances of left and right margins according to each FFT mode for the frame of FIG. 45. For example, in the 2k mode, margins of 4 and 5 symbol distances are generated from left and right, respectively, but in 8k mode, margins of 48 and 58 symbol distances are generated from left and right, respectively. That is, the longer the length of the symbol according to the FFT mode, the larger the margin area.

47 is a view showing another frame including a tracking pilot according to an embodiment of the present invention. FIG. 47 illustrates another form in which a tracking pilot is inserted into one data symbol period according to a 2k mode among the transmission modes of FIG. 44.

That is, in FIG. 47, 71 subcarriers are used to transmit tracking pilot information among 1688 subcarriers except for the TPS in 1710 subcarriers (0th to 1709th). Indicates that a subcarrier is used to transmit symbol data.

The tracking pilot has six patterns (patterns 0 to 6) and is inserted in the form of a scattered pilot. The symbol distance between one pattern and the tracking pilot of the next pattern is 4, and the symbol distance between the tracking pilots in one pattern is 24.

FIG. 48 is a diagram illustrating a margin according to the frame of FIG. 47 according to an embodiment of the present invention. FIG. When the tracking pilot is inserted in the form as shown in FIG. 47, margins are generated by 2 symbol distances and 2 symbol distances, respectively.

FIG. 48 shows the number of tracking pilots and the number of distances of left and right margins according to each FFT mode for the frame of FIG. 47. In the frame of the above-described form, margins are generated by two symbol distances and two symbol distances, respectively, for the respective modes 2k, 4k, and 8k. That is, in the case of the frame of FIG. 47, although the number of tracking pilots is slightly increased, it is possible to estimate the channel more accurately by reducing the margin area.

FIG. 49 is a diagram showing the number of symbols included in an LDPC block according to an embodiment of the present invention. FIG. In the case of using a Low Density Parity Check (LDPC) encoder as the inner encoder of the transmitter described in the above embodiments, since the size of the LDPC frame and the frame of the OFDM scheme are different, the receiving side may not synchronize the LDPC frame. A separate process is required to fit. Accordingly, the OFDM frame can be efficiently configured to easily synchronize the LDPC frame.

49 illustrates the number of symbols corresponding to one LDPC block according to the LDPC mode and the symbol mapping method. The LDPC mode is a case where the codeword length of the LDPC is 64800 bits and 16200 bits, and the case where the multiple mapping method is used as the symbol mapping method is taken as an example. 49 illustrates an example of multiple mapping using 256, 64, 16, and 4 quadrature amplitude modulation (QAM). That is, an example is a case where the inner encoder multi-maps the LDPC encoded data by mixing the 256, 64, 16, and 4 QAM schemes. The mapping method is an example, and the spirit of the present invention is not limited to the above-described numerical values and methods.

In FIG. 49, the constellation column represents a ratio of the mapping scheme used in the multiple mapping to the mapping scheme. For example, 256 QAM is mapped using only 256 QAM, and Hyb256-64_r8 uses two mapping methods, 256 QAM and 64 QAM, while the ratio of 256 QAM is 80% of the total. Indicates. The second column shows the rate of larger constellation mapping. If the ratio is 1, only a mapping method having a large constellation size is used.

Referring to FIG. 49, a case of mapping and transmitting using only 256 QAM scheme will be described. Since the 256 QAM scheme can transmit 8 bits per symbol, when the length of the LDPC codeword is 64800, the number of symbols corresponding to one LDPC block is 64800/8 = 8100. When the length of the LDPC codeword is 16200, the number of symbols corresponding to one LDPC block is 2025.

The case where the ratio of the 256 QAM scheme is 80% and the ratio of the 64 QAM scheme is 20%, that is, the case of transmission using the multiple mapping scheme of Hyb256-64_r8 will be described. In this case, if the length of the LDPC codeword is 64800, the number of symbols corresponding to one LDPC block is 8640, and if the length of the LDPC codeword is 16200, the number of symbols corresponding to one LDPC block is 2160. The number of symbols for the remaining examples is as shown in FIG. However, the type and number of mapping schemes of FIG. 49 are merely examples, and when the ratio of the 256 QAM scheme is 80% and the ratio of the 16 QAM scheme is 20%, that is, a multiple mapping scheme such as Hyb256-16_r8 may also be used. Can be. In addition, as shown in FIG. 49, two types of mapping methods may be mixed, or two or more types of mapping methods may be mixed and used.

50 is a diagram illustrating the number of LDPC blocks included in an LDPC frame as an embodiment according to the present invention. 50 illustrates the number of LDPC blocks required to configure one LDPC frame according to a multiple mapping scheme and a transmission mode (or FFT mode) when the codeword length of an LDPC is 64800.

When mapping using only 256 QAM as shown in FIG. 50, it can be seen that four LDPC blocks are included in the 8k FFT mode and one LDPC block is included in the 2k FFT mode. In addition, when the ratio of the 256 QAM scheme is 80% and the ratio of the 64 QAM scheme is 20%, it can be seen that three LDPC blocks are included in the 8k FFT mode and three LDPC blocks are included in the 2k FFT mode. have.

51 is a diagram showing the number of OFDM blocks included in an LDPC frame according to an embodiment according to the present invention. FIG. 51 illustrates the number of OFDM blocks required to configure one LDPC frame according to a symbol mapping method and an FFT mode when the codeword length of an LDPC is 64800.

When symbol mapping using only 256 QAM as shown in FIG. 51, five OFDM blocks are included in the 8k FFT mode and five OFDM blocks are included in the 2k FFT mode. When the ratio of the 256 QAM scheme is 80% and the ratio of the 64 QAM scheme is 20%, four OFDM blocks are included in the 8k FFT mode and 16 OFDM blocks are included in the 2k FFT mode. have.

FIG. 52 is a diagram illustrating the number of LDPC blocks included in an LDPC frame of another mode according to an embodiment of the present invention, and FIG. 53 is a diagram illustrating the number of LDPC blocks included in an LDPC frame of another mode according to the present invention. It is a figure which shows the number of blocks. 52 and 53 are examples of the case where the codeword length of the LDPC is 16200, respectively. 49 to 53 are numerical values calculated by calculations, and calculation methods for the respective numerical values will be omitted for convenience of description.

54 illustrates an LDPC frame structure according to an embodiment of the present invention. 54 shows a relationship between one LDPC frame, LDPC block, and OFDM block.

In the example of FIG. 54, the codeword length of the LDPC is 64800, the symbol mapping method is 256 QAM, and the FFT mode is 8k. One LDPC frame includes four LDPC blocks and corresponds to five OFDM blocks. With respect to the above conditions, it can be seen in FIG. 50 that the number of LDPC blocks included in one LDPC frame is four, and in FIG. 51, it can be seen that the number of OFDM blocks included in one LDPC frame is five. .

In FIG. 54, it can be seen that the start point of the LDPC block and the start point of the OFDM block do not coincide with each other. Accordingly, in order to construct an LDPC block again from the received OFDM blocks, the frame parsing unit on the receiving side needs a synchronization process to find the starting point of the LDPC block.

That is, the start point of the LPDC may be a place where the start point of the OFDM block and the start point of the LDPC coincide. Therefore, the start point of the LPDC frame coincides with the start point of the FDM block and the LDPC start point. In other words, the start point of the LDPC block can be known from the start point of the OFDM block that coincides with the start point of the LDPC frame. Accordingly, a scheme of transmitting an index of an OFDM block used to configure one LDPC frame for the synchronization may be used. Hereinafter, the method will be described.

55 is a diagram showing the structure of a TPS according to an embodiment according to the present invention. TPS is transmitted one bit per OFDM block, one TPS frame is a total of 68 bits. Thus, one TPS frame is transmitted on a total of 68 OFDM blocks. The bit number of FIG. 55 represents 68 bit numbers included in one TPS frame, and the bit number corresponds to the OFDM block number for transmitting the bit.

Information shown in the right column of FIG. 55 may be transmitted using the 68 bits included in the one TPS frame. For example, initialization information may be transmitted using the 0 th bit, and constellation information, that is, mapping information may be transmitted using the 25 th and 26 th bits. The 38th bit and the 39th bit may transmit information on a transmission mode.

56 illustrates constellation information according to an embodiment of the present invention. When the 25th and 26th bits of the TPS bits of FIG. 55 are used, constellation information for up to four types can be transmitted. Therefore, when more types of constellation information are transmitted, the number of bits must be increased. 56 shows constellation information identified using four bits in which the two bits are increased.

That is, using the 25th to 28th bits, the 25th to 28th bits are '0000' (25th bit '0', 26th bit '0', 27th bit '0', 28th bit '0' In case of), symbol data mapped using only QPSK is transmitted, and in case of '0111', symbol data mapped in a multiple mapping method with 64% of 64 QAM schemes and 60% of 16 QAM schemes is transmitted. .

In the example of FIG. 56, since 16 types of the multiple mapping schemes illustrated in FIGS. 49 to 53 are used, four (25th to 28th) bits are used, but the type of the multiple mapping scheme increases or decreases. The number of bits to be used can be adjusted according to the kind number.

The receiver further transmits information about the LDPC mode in addition to the mapping information in the TPS for synchronization to find the start point of the LDPC block.

57 shows LDPC mode information according to an embodiment according to the present invention. 55 does not include bits for transmitting information about the LDPC mode. Therefore, the LDPC mode information is transmitted by using the 42nd bit and the 43rd bit among the reserved bits of 40 to 53 bits. 57 shows LDPC mode information identified using the two bits.

That is, the LDPC used when the 42nd and 43rd bits are '00' has a codeword length of 64800, and the used LDPC has a codeword length of 16200 when '01'. In the above example, since the two modes of 64800 and 16200 are used as examples, two (42th and 43rd) bits are used. However, when the number of modes increases, the number of bits used may be increased according to the number of modes.

58 is a diagram illustrating a structure of an extended TPS according to an embodiment according to the present invention. 58 illustrates a structure of an extended TPS including the information of FIGS. 56 and 57. In the TPS frame of FIG. 58, as the constellation information is further increased by 2 bits as shown in FIG. 56, the position of the bits after the constellation information is pushed by two bits to adjust the position. The receiving side can receive the TPS frame as shown in FIG. 58 and know the constellation information, LDPC mode information, and transmission mode information.

59 is a diagram showing OFDM block index information according to an embodiment according to the present invention. The TPS frame of FIG. 55 does not include bits for transmitting information on the OFDM block index. Therefore, the OFDM block index information is transmitted using the 44 th to 48 th bits among the reserved bits. 59 shows OFDM block index information identified using the five bits.

In the example of FIG. 51 and FIG. 53, one LDPC frame may consist of up to 28 OFDM blocks. Therefore, an OFDM block index that can distinguish the 28 OFDM blocks must be included in the TPS frame and transmitted. The OFDM block indicated by the OFDM block index may be any of the last OFDM blocks from the OFDM block at which the TPS frame starts. For example, the index may be an index indicating a first block of the maximum 28 OFDM blocks or an index indicating a last block. This may vary depending on the implementation, and the block may be identified according to the promise of the sender and the receiver.

In FIG. 59, when the 44th bit to the 48th bit are '00000', the OFDM block index is 1 and when the '11111', the OFDM block index is 32. Each time the bit value is increased by one, the index value is also increased by one. In the above example, since 28 blocks must be distinguished, 5 (44th to 48th) bits are used, but the number of bits used can be adjusted according to the maximum number of blocks.

60 is a diagram illustrating a TPS structure including OFDM block index information according to an embodiment according to the present invention. The TPS frame includes information about FIGS. 56 and 57 and information about FIG. 59.

The receiving side may receive the TPS frame as shown in FIG. 60 to know constellation information, LDPC mode information, transmission mode information, and index information of a specific OFDM block included in one LDPC frame. Accordingly, the number of LDPC blocks and the number of OFDM blocks included in one LDPC frame can be known using the constellation information, the LDPC mode information, the transmission mode information, and the information of FIGS. 50 to 53 obtained from the TPS frame. have. The start point of the LDPC block may be determined using the number information of the LDPC blocks included in the one LDPC frame, the number information of the OFDM blocks, and the specific OFDM block information included in the LDPC frame.

For example, it is assumed that the OFDM block index information indicates a third block among OFDM blocks included in one LDPC frame. As described above, the number of LDPC blocks and the number of OFDM blocks included in one LDPC frame can be known, and the LDPC block and the OFDM block start before two blocks of the block indicated by the OFDM block index among the OFDM blocks. Able to know. However, the receiving side should know the information about the above 50 to 53 in advance.

As described above, using the TPS frame information having the structure as shown in FIG. 60, the receiving side can determine the start point of the LDPC block. However, the receiving side should know the information about the above 50 to 53 in advance, it is possible to find the starting point of the LDPC block using the information and the information contained in the received TPS frame.

Hereinafter, a description will be given of a method for allowing a receiving side to immediately find a start point of an LDPC block without using the information of FIGS. 50 to 53.

61 is a diagram showing LDPC block information according to an embodiment of the present invention. In FIG. 61, information on the number of LDPC blocks included in one LDPC frame may be transmitted using bits in a reserved area that are not used among the bits of the TPS frame.

For example, information on the number of the LDPC blocks is transmitted using the 49 th bit to the 52 th bit. As shown in FIG. 50 and FIG. 52, the maximum number of LDPC blocks that can be included in one LDPC frame is 48 according to each LDPC mode. However, since the number of blocks used in the above is only 10 (1, 2, 3, 4, 6, 8, 12, 16, 24, 48), in FIG. 61, 4 bits are used for the LDPC block. Send count information.

In FIG. 61, when the 49th to 52nd bits are '0000', the number of LDPC blocks included in one LDPC frame is 1, and when '0111' is 16. In FIG. 61, the remaining values other than the values corresponding to the ten types of the blocks used in FIGS. 50 and 52 are reserved. In the above example, since 10 types of values must be distinguished, four (49th to 52nd) bits are used, but the number of bits used can be adjusted according to the value type of the number of blocks used. In addition, the bit value corresponding to the block number value is an example, and may vary depending on implementation.

62 is a diagram illustrating OFDM block information according to an embodiment of the present invention. In case of FIG. 62, information on the number of OFDM blocks is transmitted using 53rd to 57th bits. 51 and 53, the maximum number of OFDM blocks that can be included in one LDPC frame according to each LDPC mode is 28. Therefore, in FIG. 62, the number information of the OFDM block is transmitted using 5 bits. In FIG. 62, 5 bits are used. However, as shown in FIG. 61, the required number of bits may be used according to the type of the number of blocks.

In FIG. 62, when the 53 th to 57 th bits are '00000', the number of OFDM blocks included in one LDPC frame is 1, and when the 11 th bit is '11111'. Each time the bit value increases by 1, the value of the number of blocks also increases by one.

In the above example, five (53th to 57th) bits are used to distinguish up to 28 block number values, but the number of bits used may be adjusted according to the block number value to be distinguished.

FIG. 63 is a diagram illustrating a structure of a TPS including proposed information according to an embodiment of the present invention. 63 is a structure in which the information of FIGS. 56, 57, 59, 61, and 62 is included in the TPS frame structure of FIG. 55. Accordingly, the receiving side receives the TPS frame having the structure as shown in FIG. 63, and includes the constellation information, the LDPC mode information, the transmission mode information, the index information for a specific OFDM block included in one LDPC frame, and one LDPC frame. LDPC block number information and OFDM block number information included in one LDPC frame may be obtained.

Accordingly, the receiving side may know the starting point of the LDPC block by using the information included in the received TPS frame without using the information of FIGS. 50 to 53.

In the case of having the TPS structure as shown in FIG. 63, the 58 th to 71 th bits include BCH error protection information. In the case of DVB, the BCH error protection information can be obtained using an original systematic code of BCH (127, 113, t = 2). 127 denotes the total number of transmission bits, 113 denotes the number of message bits, and the number of bits corresponding to the total number of transmission bits minus the number of message bits indicates the number of parity bits. And t = 2 represents the number of bits which can be error corrected.

In order to obtain the BCH error protection information, 60 bits of zero are inserted and encoded in an input bit string of a BCH encoder. By removing the inserted zero bits of the encoded and output bits, a shortened BCH code of BCH (67, 53, t = 2) can be obtained.

As shown in FIG. 63, in order to obtain a BCH code for a TPS having 57 bits of message bits and 71 bits of total transmission bits, 56 bits of zeros are inserted and encoded into an input bit string of the BCH encoder. A shortened BCH code of BCH (71, 57, t = 2) can be obtained by removing 56 bits of zero from the encoded and output bits.

64 is a diagram illustrating preamble period information according to an embodiment of the present invention. In case of FIG. 64, the preamble period information may be included in the TPS frame and transmitted. As described above, a pilot symbol period may be used as a preamble in a transmission frame as shown in FIG. 7 or 43. In this case, the period of the preamble refers to the period of the pilot symbol period.

The pilot symbol period includes a known signal that can be used as a pilot, and the receiver performs signal synchronization, channel estimation, channel compensation, etc. using the pilot signal. The data symbol interval including the data to be transmitted is included between the pilot symbol interval and the next pilot symbol interval and transmitted. The transmitter may adjust the period of the pilot symbol interval to obtain a tradeoff between data capacity and transmission reliability.

For example, when the channel environment is not good or the channel environment changes, such as a mobile reception environment, the pilot symbol section may be inserted more frequently to speed up the period. Alternatively, when the channel environment is good or fixed reception is performed, the pilot symbol interval may be inserted less.

As described above, the period of the pilot symbol interval may be different. Accordingly, the transmitting end transmits the preamble period information shown in FIG. 64 to the receiving end so that the receiving end can know the period of the pilot symbol interval. The example of FIG. 64 illustrates a case in which a preamble is inserted every 10 symbols, 15 symbols, 20 symbols, and 25 symbol intervals by using two bits of the 58th bit and the 59th bit. However, the number and period information of the bits is an embodiment, and the spirit of the present invention is not limited by the numerical values.

65 is a diagram illustrating a TPS structure including preamble period information according to an embodiment of the present invention. 65 shows a structure in which the preamble period information is further included in the TPS of FIG.

In order to obtain a BCH code for a TPS having 59 bits of message bits and 73 bits of total transmission bits using the original systematic code of BCH (127, 113, t = 2), an input bit of a BCH encoder is obtained. Encode the column by inserting 54 bits of zeros. A shortened BCH code of BCH (73,59, t = 2) can be obtained by removing 54 bits of zero from the encoded and output bits.

66 is a diagram illustrating a relationship between a pilot symbol interval and a single frequency network according to an embodiment of the present invention. In the transmission frame as described with reference to FIG. 7 or 43, the pilot symbol period may have a structure as described with reference to FIG. 8A.

The pilot symbol interval shown in FIG. 66 is divided into even and odd pilots by interleaving pilot carrier information. In addition, a single frequency network (SFN) is divided into an even carrier region (A) and an odd carrier region (B), and data is transmitted using information corresponding to an even pilot and an odd pilot, respectively.

67 is a diagram showing the structure of a pilot symbol according to an embodiment of the present invention. The upper diagram of FIG. 67 is a structure of a pilot symbol interval including an even pilot carrier, and the lower diagram is a structure of a pilot symbol interval including an odd pilot carrier. Null carrier information is included in addition to each even pilot carrier and odd pilot carrier information.

That is, the antenna of the even carrier region (A) transmits data using a pilot symbol interval including an even pilot carrier as shown in the upper part of FIG. 67, and the antenna of the odd carrier region (B) is shown in FIG. Data is transmitted using a pilot symbol period including an odd pilot carrier as shown in the lower part of the figure. The data of the data symbol interval transmitted in the even carrier region A and the odd carrier region B is the same, except that the pilot carrier information of the pilot symbol interval is different from the odd carrier and the even carrier.

As described above, when the even pilot and the odd pilot are divided to form a pilot symbol interval, even if the power of the pilot included in the pilot symbol interval is doubled, the overall power does not change. Therefore, the receiver can estimate the channel by using the pilot having the power of twice the size, and more accurate channel estimation is possible.

In addition, as shown in FIG. 66, in the region C where the even carrier region A and the odd carrier region B overlap, the even pilot and the odd pilot signals may be simultaneously received. Therefore, in the region C, more accurate channel estimation can be performed using an even pilot and an odd pilot signal. For example, channel estimation may be performed using a pilot having a better channel condition, or both pilots may be compensated for and channel estimation may be performed using both pilots. Accordingly, as shown in FIG. 66, antennas are arranged such that some other carrier regions ex and B overlap with each other around one carrier region ex and A, so that accurate channel estimation can be performed even in a region relatively far from the antenna. have.

When using a pilot symbol interval including an even pilot and an odd pilot as described above, the receiver can easily detect and synchronize the pilot symbol interval. As shown in FIG. 67, a null symbol (zero energy) carrier is included in the pilot symbol period, but since there is no carrier having zero energy in the data symbol period as described above, the pilot symbol is detected only by detecting the power of the carrier. The interval (or preamble) can be synchronized.

68 is a block diagram schematically showing another example of a signal transmission apparatus according to an embodiment of the present invention. FIG. 68 shows an apparatus for transmitting signals using the multiple encoding and multiple mapping schemes and the pilot symbol structure described with reference to FIG. 67 among the signal transmission apparatuses of the above-described embodiments. That is, the pilot symbol structure described with reference to FIG. 67 may be used in all embodiments, such as FIGS. 1, 13, 25, 30, 34, 39, and 41, in addition to the above embodiment. In addition, in the component of FIG. 68, an additional component that does not need to be added or required according to an implementation example, such as an interleaving process between an outer encoder and an inner encoder, or a linear precoding process, is not performed. May not be used. Each component of the signal transmission apparatus of FIG. 68 is the same as described in each of the above embodiments, and will be described below with reference to differences.

The symbol data interleaved by the second interleaver 6850 is input to the frame forming unit 6860. The frame forming unit 6860 forms a frame by inserting a pilot signal to modulate the output signal by the OFDM method. In this case, the frame forming unit 6860 forms a frame having a pilot symbol interval having the structure as shown in FIG. For example, the frame forming portion of the even carrier region forms a frame having a pilot symbol section having the same structure as in the upper view of FIG. 67, and the frame forming portion of the odd carrier region has a pilot symbol having the structure shown in the lower view of FIG. 67. Form a frame with sections.

Each transmission frame formed by the frame forming unit 6860 is OFDM modulated and transmitted through the modulator 6070.

69 is a block diagram schematically showing another example of a signal receiving apparatus according to an embodiment of the present invention. 69 illustrates an apparatus for receiving a signal transmitted using a multiple encoding and a multiple mapping scheme and the pilot symbol structure described with reference to FIG. 67 among the signal receiving apparatuses of the above-described embodiments. The receiver of FIG. 69 corresponds to the transmitter of FIG.

Likewise, each component of the signal receiving apparatus of FIG. 69 is the same as described in each of the above embodiments, and will be described below with reference to differences.

Data demodulated by the demodulator 6920 is input to the frame parser 6930. The frame parser 6930 may parse the frame input from the demodulator 6920 and output symbol data of a data symbol interval excluding a pilot symbol. In this case, the frame parsing unit 6930 may synchronize the pilot symbol period (or preamble) only by detecting the power of the carrier.

The symbol data parsed by the frame parser 6930 is output to the first deinterleaver 6950. The first deinterleaver 6950 recovers the order of the symbol data by deinterleaving in a manner corresponding to the method interleaved by the second interleaver 6850 of FIG. 68.

The pilot data parsed by the frame parser 6930 is output to the channel estimator 6940. The channel estimator 6940 estimates a channel by using the pilot and known pilot information output from the frame parser 6930 and outputs the estimated result to the equalizer 6960. The equalizer 6960 equalizes the symbol data whose order is restored in the first deinterleaver 6950 by using the channel estimate value.

70A and 70B illustrate a proposed frame structure according to an embodiment of the present invention. The proposed frame structure can be applied to each of the above-described transmission and reception embodiments. In FIG. 70A and FIG. 70B, row 1 shows a pilot symbol period (preamble). The preamble and the preamble include a number (1 ~ P-1) of the number of data symbol intervals less than the preamble period (P).

As described with reference to FIG. 67, only even or odd pilot carrier information may be transmitted in a pilot symbol period of a frame as illustrated in FIG. 7 or 43. FIG. 70A illustrates a frame including a pilot symbol interval including only even pilot carrier information and a data symbol interval including continuous pilot (CP) pilot information along with symbol data to be transmitted. The CP pilot can be used to track channel changes and estimate frequency offset at the receiving end.

As described above with reference to FIG. 44, in the 2k mode, there are 1688 data transmission subcarriers in the data symbol period. FIG. 70A illustrates an embodiment in which 68 of them are used to transmit a CP pilot and the remaining 1620 subcarriers are used to transmit symbol data.

As shown in FIG. 70A, in the 2k mode, one symbol period includes 1705 (0 to 1704) subcarrier information. In the pilot symbol period, pilot information is included only at positions of even carriers (k = 0, 2, 4, ..., 1704) among the carriers. The CP symbol information is included in the data symbol section together with the symbol data. CP pilot information is inserted into 68 subcarriers in each data symbol period. 70A shows an example of inserting 68 CP pilot information into an even carrier position. For example, the 0th, 24th,... CP pilot information is inserted into the 1682 th and 1704 th subcarriers. The location of the CP pilot is one embodiment. The position of the CP pilot is irregularly arranged to maintain the SNR of the average CP in all channels to ensure channel tracking performance regardless of the channel. In the 70a, a CP pilot may be inserted at an odd carrier position which is not even, or may be inserted evenly and evenly.

70B illustrates a frame including a pilot symbol period including only odd pilot carrier information and a data symbol period including CP pilot information together with symbol data to be transmitted. FIG. 70B illustrates an embodiment in which 68 out of 1688 subcarriers capable of transmitting data are used to transmit CP pilot information and the remaining 1620 subcarriers are used to transmit symbol data.

In the pilot symbol period, pilot information is included only in positions of odd carriers (k = 1, 3, 5, ..., 1703) among the carriers. The data symbol interval includes CP pilot information together with symbol data. CP pilot information is inserted into 68 subcarriers in each data symbol period. FIG. 70B shows an example of inserting 68 CP pilot information into an odd carrier position. Similarly, the position of the CP pilot is an embodiment, and the CP pilot may be inserted in an even carrier position instead of an odd number, or may be inserted evenly or evenly.

71 to 73 are diagrams illustrating insertion positions of CP pilot information according to respective modes according to an embodiment of the present invention. FIG. 71 illustrates a position where 68 CP pilot information is inserted in the 2k mode, and FIG. 72 illustrates a position where 135 CP pilot information is inserted in the 4k mode. 73 shows a position where 269 CP pilot information are inserted in the 8k mode. The positions of the 4k mode of FIG. 72 and the 8k mode of FIG. 73 are examples of repeating the arrangement of the 2k mode of FIG. 71 twice and four times, respectively. However, in the case of the 4k mode and the 8k mode, as shown in FIG. 72 and FIG. 73, the position where the arrangement of the 2k mode is repeated twice and four times may be used, or other positions may be used.

In the example of FIGS. 71 to 73, CP pilot information is inserted at even carrier positions, but CP pilot information may be inserted at odd carrier positions, or may be inserted at even and odd positions.

74A and 74B illustrate a structure of a frame having the same CP pilot position as an embodiment according to the present invention. In pilot symbol intervals (preambles) shown in FIGS. 74A and 74B, pilot information is inserted into even and odd carrier positions, respectively. In the data symbol period, CP pilot information is inserted in the same carrier position (common CP) to transmit data. For example, in FIGS. 74A and 74B, 0th, 25th,... CP pilot information is inserted into the 1682th and 1704th subcarrier positions, respectively. However, the position of the CP pilot is an embodiment, and may be inserted in the even carrier position, the odd carrier position, or may be inserted without distinguishing the even, odd carrier position.

74A and 74B, the frame having the structure as shown in FIG. 66 may be used when transmitting signals by dividing the even carrier region (A) and the odd carrier region (B) in a single frequency network. have. The transmission signal of the even carrier region A includes even pilot carrier information in the pilot symbol period, and the transmission signal of the odd carrier region B includes odd pilot carrier information in the pilot symbol period. In this case, CP pilot information is inserted in the data symbol period included in the transmission signal of each region, and the CP pilot information is inserted in the same position.

For example, a frame including even pilot carrier information in a pilot symbol period as shown in FIG. 74A may be transmitted through an antenna of an even carrier region (A), and odd pilot carrier information may be transmitted in a pilot symbol period as shown in FIG. 74B. The containing frame may be transmitted via an antenna of an odd carrier zone (B).

75 is a diagram illustrating an insertion position of common CP pilot information according to an embodiment of the present invention. 75 illustrates a position where 68 CP pilot information is inserted in the 2k mode. In the case of the 4k mode and the 8k mode, the position where the arrangement of the 2k mode of FIG. 75 is repeated two or four times may be used, or another position may be used. Similarly, the common CP pilot information may be inserted at even carrier positions or at odd carrier positions. Alternatively, even and odd numbers may be inserted.

74A and 74B illustrate a case of transmitting / receiving a single input / output (SISO) using a single frequency network, but the above frame structure may be applied to multiple input / output (MIMO) transmission and reception.

76A to 76C illustrate a structure of a multi-input / output transmission frame according to an embodiment of the present invention. 76A to 76C are diagrams illustrating positions of a pilot and a CP pilot of a preamble along a transmission path, respectively. In the example of FIGS. 76A to 76C, data is transmitted using two transmission paths ant 1 and ant 2. Subcarrier positions of the CP pilot inserted in the data symbol interval are the same for both transmission paths.

As described above with reference to FIG. 1, in the multi-input / output method, the receiving end should distinguish each transmission path. In the example of FIGS. 76A to 76C, a transmission path may be distinguished by using a pilot insertion position of a pilot symbol period (preamble).

For example, the transmission signal of the first transmission path ant 1 includes even pilot carrier information in a pilot symbol period, and the transmission signal of the second transmission path ant 2 includes odd pilot carrier information in a pilot symbol period. do. The receiver may distinguish the transmission path by using the position of the pilot inserted in the pilot symbol interval of the received frame.

CP pilot information is inserted into a data symbol section of a signal transmitted through each transmission path. The CP pilot information may be inserted in the same position for each transmission path or in another position.

76A to 76C illustrate an example of inserting CP pilot information in the same position for each transmission path. 76A illustrates an example of inserting CP pilot information into even carrier positions, and FIG. 76B illustrates an example of inserting CP pilot information into odd carrier positions. 76C shows an example of inserting CP pilot information regardless of even and odd carrier positions.

The location of the CP pilot information of FIGS. 76A through 76C is one embodiment, and another location may be used according to an implementation example.

In the frame structure including the pilot symbol period and the CP pilot information described above, the pilot and the CP pilot information of the data symbol period may be scrambled. The scrambling of the pilot information is used to remove the DC component of the transmission signal and to facilitate detection of the preamble and correction of the frequency offset at the receiving end.

For example, Pseudo Random Binary Sequence (PRBS) may be used to scramble the pilot information. In this case, the same PRBS may be used for the pilot of the pilot symbol period and the CP pilot information of the data symbol period, or scrambled using different PRBSs.

Equation 5 below is an embodiment for the scramble. The pilot of the pilot symbol interval and the CP pilot information of the data symbol interval may be scrambled using the equation (5). Alternatively, the CP pilot information may be scrambled using Equation 5, and the pilot of the pilot symbol interval may be scrambled or not scrambled using the equation. Determining a pilot to scramble using the above-described equation may vary according to implementation.

In Equation 5, 'C _k ' represents pilot information at a position corresponding to 'k', and 'W _k ' represents a PRBS value for scramble. 'Re (C _k )' represents a real value of the 'C _k ' value, and 'Im (C _k )' represents an imaginary value of the 'C _k ' value. 'Bf' is a power boosting factor. The numerical value of the power boosting factor is an embodiment, and the numerical value can be adjusted to obtain a tradeoff between channel estimation performance and SNR improvement of data.

When scrambling CP pilot information of each frame structure described above using Equation 5, since only the CP pilot is used, the power reduction of data due to boosting is smaller than that of DVB-T, and more CP pilots than DVB-T are. Better channel tracking performance.

FIG. 77 is a diagram illustrating a pseudo random binary generator (PRBS) generator according to an embodiment of the present invention. The PRBS value W _k of Equation 5 may be obtained using the generator.

The PRBS generator includes a bit delay unit 7700 and an operation unit 7710. The embodiment of FIG. 77 includes eleven one-bit delay units and an XOR gate. The number of bit delay units and the types of gates are exemplary embodiments, and the number of gate delay units, types, and positions of the delay units may vary according to implementation.

Each bit delay unit of the PRBS generator of FIG. 77 is input with an initial value of 1, and the XOR gate 7710 performs an XOR operation by inputting an output of a 9th bit delay unit and an output of an 11th bit delay unit. The output calculated by the XOR gate 7710 may be input to the 1st bit delay unit, and the output value of the 11th bit delay unit may be used as the PRBS value W _k of Equation 5 above. In the case of the PRBS generator of FIG. 77, after all 11 initial values are output, a value calculated by the XOR gate 7710 is output.

또는

를 얻을 수 있다.As described above, the PRBS generator may output a value of 1 or 0. Substituting the value of 1 or 0 into Equation 5 results in a pilot real value Re (C _k ).

or

Can be obtained.

78 is a block diagram schematically showing another example of a signal transmission apparatus according to an embodiment of the present invention. FIG. 78 is a view illustrating an apparatus for transmitting signals using a frame structure including multiple encoding and multiple mapping schemes and CP pilot information described in the embodiments, among the signal transmission apparatuses according to the above-described embodiments.

The signal transmission apparatus of FIG. 78 is the same as that described with respect to the signal transmission apparatus of FIG. 68 except that CP pilot information is inserted in the data symbol interval of the transmission frame as in the above-described embodiments. In the signal transmission apparatus of FIG. 78, necessary components may be added or unnecessary according to an implementation example, such as an embodiment for performing an interleaving process between an outer encoder and an inner encoder, or not performing a linear precoding process. May not be used. Hereinafter, a description will be given of the differences.

The symbol data interleaved by the second interleaver 7850 is input to the frame forming unit 7860. The frame forming unit 7860 forms a frame by inserting a pilot signal to modulate the output signal by the OFDM method. In this case, the frame forming unit 7860 forms a frame including a pilot symbol period and a data symbol period as described in the above embodiments. CP pilot information as described above is inserted into the data symbol period. The transmission frame formed by the frame forming unit 7860 is OFDM modulated and transmitted through the modulator 7780.

79 is a block diagram schematically showing another example of a signal receiving apparatus according to an embodiment of the present invention. The receiver of FIG. 79 corresponds to the transmitter of FIG. 78. In the signal receiving apparatus of FIG. 79, a necessary component may be further added or an unnecessary component may not be used according to an embodiment.

Similarly, each component of the signal receiving apparatus of FIG. 79 is the same as described in each of the above embodiments, and will be described below with reference to differences.

The first synchronizer 7910 may use an offset result of the frequency domain of data output from the demodulator 7920 and the second synchronizer 7730 to obtain synchronization of a frequency domain signal. The second synchronizer 7930 parses the frame output from the demodulator 7920 to extract CP pilot information and track the channel. That is, the second synchronizer 7930 outputs frequency offset correction information of the received signal to the first synchronizer 7910 using CP pilot information included in each data symbol section of the frame. The first synchronization unit 7910 may synchronize more precisely by using the frequency offset correction information output from the second synchronization unit 7930.

Data demodulated by the demodulator 7920 is output to the frame parser 7940. The frame parser 7940 may parse a frame input from the demodulator 7920 and output symbol data of a data symbol period excluding a pilot symbol. In this case, the frame parser 7940 may synchronize the pilot symbol period (or preamble) only by detecting the power of the carrier.

If the transmitter scrambles pilot information of a CP pilot or a pilot symbol interval using PRBS, the second synchronizer 7730 or the frame parser 7940 must descramble it.

80 is a diagram illustrating a descramble device according to one embodiment according to the present invention. The descrambler includes a PRBS generator 8000, a selection output unit 8010, and an operation unit 8020.

The PRBS generator 8000 generates and outputs a binary sequence such as the PRBS generator described with reference to FIG. 77. The PRBS generation unit 8000 outputs 0 or 1, and the output is input to the selection output unit 8010.

The selection output unit 8010 selectively outputs one of two inputs (1 or -1) using a value of 0 (false) or 1 (true) as a control value. For example, when 0 is input from the PRBS generator 8000 in FIG. 80, the selection output unit 8010 outputs 1, and when 1 is input from the PRBS generator 8000, the selection output unit 8010 is-. Outputs 1 The value output from the selection output unit 8010 is input to the operation unit 8020.

값을 갖는다. 즉, 상기 채널을 거친 파일럿은 스크램블된 파일럿(

)에 채널 전달함수(CTF : Channel Transfer Function)를 컨벌루션(convolution)한 값이 된다.The calculation unit 8020 multiplies and outputs the pilot received through the channel and the value output from the selection output unit 8010. If the pilot is scrambled and transmitted according to the equation (5), the pilot passing through the channel

Has a value. That is, the pilot that passed through the channel is a scrambled pilot (

) Is the value of convolution of the channel transfer function (CTF).

As described in Equation 5, the scrambled pilot has a bf × 1 value when W _k is 0 and a bf × -1 value when W _k is 1. The select output unit 8010 of FIG. 80 outputs 1 when 0 is input and -1 when 1 is input.

이 된다.Accordingly, the operation unit 8020 may descramble and output the pilot scrambled according to the PRBS by the transmitter. 80, the descrambled value is

Becomes

The symbol data parsed by the frame parser 7940 is output to the first deinterleaver 7960. The first deinterleaver 7960 deinterleaves the interleaved symbol data in a manner corresponding to the interleaving method of the second interleaver 7850 of FIG. 78 to restore the order of symbol data.

The pilot data parsed by the frame parser 7940 is output to the channel estimator 7950. The channel estimator 7950 estimates a channel by using the pilot and known pilot information output from the frame parser 7940 and outputs the estimated result to the equalizer 7970. The equalizer 7970 equalizes the symbol data whose order is restored in the first deinterleaver 7960 by using the channel estimate value.

FIG. 81 is a diagram of comparing TPS transmission bits per symbol according to an embodiment of the present invention. FIG. The receiving end can decode the TPS information only after receiving all the TPS information in one cycle. In the case of the TPS, one TPS bit is included in one symbol and transmitted. In this case, it takes symbol time as many as TPS bits for TPS synchronization.

Accordingly, by further including TPS information in the data symbol period, time for TPS synchronization can be reduced. For example, some of the CP pilot insertion positions may be used to transmit TPS to reduce time for TPS synchronization. That is, in addition to the subcarrier for transmitting the existing TPS information, at least one piece of TPS information may be further included in place of the pilot information at the CP pilot information insertion position of the data symbol period. In addition, the TPS bit may be transmitted only in one CP pilot information insertion position in a data symbol period, or the TPS bit may be repeatedly transmitted in multiple CP pilot information insertion positions in one data symbol interval.

For example, it is assumed that one TPS bit is repeatedly transmitted 17 times in one data symbol period. In this case, in the 2k mode, the TPS bit may be transmitted in 17 subcarriers among the 68 pilot carrier positions and the CP pilot information may be transmitted in the remaining 51 subcarriers. In the 4k mode and the 8k mode, CP pilot information may be included in 101 and 201 subcarriers, respectively.

 FIG. 81 is a diagram illustrating TPS synchronization latency when transmitting 1-bit TPS bits and transmitting 2-bit TPS bits in one symbol based on the TPS proposed in FIG. In the figure, time represents an expected waiting time when one symbol length is assumed to be 1120usec (DVB-T, 8k-mode), which is a value obtained by multiplying the symbol length by a total symbol.

When transmitting one bit of TPS bit in one symbol, 72 symbols should be received for TPS synchronization, and in case of 8k-mode, up to 19 symbols should be received for LDPC synchronization as shown in FIG. 51. The total symbol is the maximum symbol time taken for the next sync if one symbol is missed. For example, if the first symbol is missed, the maximum symbol time is taken for the next synchronization. When transmitting one bit of TPS bits in one symbol, the maximum symbol time is 72 (TPS sync) x 2 + 19 (LDPC sync)-1 = 162, and two bits of TPS bits are transmitted in one symbol. In this case, the maximum symbol time is 36 (TPS sync) x 2 + 19 (LDPC sync)-1 = 90. As described above, data can be efficiently transmitted in terms of latency or data.

82A is a flowchart illustrating a signal transmission process according to an embodiment of the present invention.

The signal transmission apparatus maps forward error correction encoded data to symbol data so that an error of the transmission data can be detected and corrected (S8200). For example, LDPC encoding Turbo encoding may be used for the forward error correction encoding, and multiple encoding schemes may also be used. As the mapping method, a QAM, QPSK, an optical constellation mapping method, or the like may be used, and a multiple mapping method may also be used.

In operation S8202, a transmission frame is formed using the symbol-mapped data. For example, the transmission frame may include a pilot symbol interval and a data symbol interval, and the data symbol interval may include CP pilot information.

The signal transmission apparatus modulates and transmits the formed transmission frame according to a transmission scheme (S8204). If the signal transmission apparatus transmits data using a pilot symbol section including only the even pilot carrier information and a pilot symbol section including only the odd pilot carrier information, the even and odd carrier regions are distinguished as shown in FIG. 66. Data can be transferred.

82B is a flowchart illustrating a signal reception process according to an embodiment of the present invention.

The signal receiving apparatus receives and synchronizes a signal transmitted from the transmitting apparatus, and demodulates the frame data (S8210). The demodulated frame data is parsed to extract pilot and symbol data included in the frame (S8212).

As described above, in the case of a frame including a pilot symbol section including only even pilot carrier information and a pilot symbol section including only odd pilot carrier information, the pilot and symbol data are synchronized by synchronizing the pilot symbol period by detecting the power of the carrier. Can be extracted.

When the CP pilot information is included in the data symbol interval, the pilot information can be extracted to track the channel to more accurately correct the frequency offset.

The receiving apparatus estimates a transmission channel using the pilot information extracted in the pilot symbol period, and equalizes the extracted symbol data using the estimated channel (S8114). The equalized symbol data is de-mapping to be restored to the corresponding bit data, and the error is corrected by performing forward error correction decoding on the bit data (S8116). The demapping method and the error correction decoding method may use a method corresponding to the method mapped by the transmitter and the error correction encoded method.

The signal transceiving method and the signal transceiving apparatus are not limited to the above examples, and may be applied to all signal transceiving systems such as broadcasting or communication.

The present invention is not limited to the above-described embodiments, and can be modified by those skilled in the art as can be seen from the appended claims, and such variations are within the scope of the present invention. .

1 is a block diagram schematically showing an apparatus for transmitting a signal as an embodiment according to the present invention;

2 is a block diagram schematically illustrating an interleaver and a forward error correction encoder according to an embodiment of the present invention.

3 illustrates an interleaver for interleaving input data according to an embodiment of the present invention.

4 is a diagram illustrating an example of another interleaver according to an embodiment of the present invention.

5 is a diagram illustrating a specific example of the interleaver of FIG. 4 as an embodiment according to the present invention.

6 is a diagram illustrating an example of a multiple input / output encoding scheme according to an embodiment of the present invention.

7 is a diagram illustrating a structure of a transmission frame according to an embodiment of the present invention.

8 (a) is a diagram illustrating a structure of a pilot symbol interval according to an embodiment of the present invention.

8 (b) illustrates another structure of a pilot symbol period according to an embodiment of the present invention.

9 is a block diagram schematically illustrating an apparatus for receiving a signal according to an embodiment of the present invention.

10 is a diagram illustrating an example of a multiple input / output decoding scheme according to an embodiment of the present invention.

11 is a diagram illustrating a specific example of FIG. 10 as an embodiment according to the present invention.

12 is a block diagram schematically illustrating a deinterleaver and a forward error correction decoder according to an embodiment of the present invention.

13 is a block diagram schematically showing another example of a signal transmission apparatus according to an embodiment of the present invention.

14 is a block diagram schematically showing another example of a signal receiving apparatus according to an embodiment of the present invention.

FIG. 15 is a view schematically showing the position of an optimal constellation point according to an embodiment of the present invention.

16 is a flowchart illustrating a procedure of determining an optical constellation point according to an embodiment of the present invention.

17 is a diagram schematically showing an optical constellation having 16 points as an embodiment according to the present invention.

18 is a diagram schematically showing an optical constellation having 64 points as an embodiment according to the present invention.

19 is a view schematically showing an optical constellation having 256 points as an embodiment according to the present invention.

20 is a view schematically showing another optical constellation having 256 points as an embodiment according to the present invention.

21 is a block diagram schematically illustrating a decision boundary of an optical constellation having 64 points;

FIG. 22A schematically illustrates a symbol demapper for demapping a received optical constellation symbol according to an embodiment of the present invention. FIG.

FIG. 22B is a schematic representation of another symbol demapper for demapping received optical constellation symbols as an embodiment in accordance with the present invention. FIG.

FIG. 23 is a diagram schematically illustrating a process of demapping a received optical constellation symbol according to an embodiment of the present invention.

24 is a diagram schematically illustrating a process of demapping a received optical constellation symbol in an edge region according to an embodiment of the present invention.

25 is a block diagram schematically illustrating an apparatus for transmitting a signal according to an embodiment of the present invention.

FIG. 26 is a block diagram schematically illustrating a multiple mapper according to an embodiment of the present invention. FIG.

27 illustrates a bit stream distribution scheme according to an embodiment of the present invention.

28 is a block diagram schematically illustrating an apparatus for receiving a signal according to an embodiment of the present invention.

29 is a block diagram schematically illustrating a multiple demapper according to an embodiment of the present invention.

30 is a block diagram schematically illustrating an apparatus for transmitting a signal using multiple encodings according to an embodiment of the present invention.

31 is a block diagram schematically showing multiple encoders according to an embodiment of the present invention.

32 is a block diagram schematically illustrating a signal receiving apparatus for receiving a multi-encoded signal according to an embodiment of the present invention.

33 is a block diagram schematically illustrating multiple decoders according to an embodiment of the present invention.

34 is a block diagram schematically illustrating an apparatus for transmitting a signal using multiple encoding and multiple mapping according to an embodiment of the present invention.

35 is a block diagram schematically illustrating a signal receiving apparatus for receiving a multi-encoded and multi-mapped signal according to an embodiment of the present invention.

36 is a block diagram schematically illustrating another signal receiving apparatus for receiving multiple encoding and multiple mapped signals according to an embodiment of the present invention.

37 is a block diagram schematically illustrating a channel estimator in accordance with an embodiment of the present invention.

38 is a block diagram schematically illustrating an equalization unit according to an embodiment of the present invention.

39 is a block diagram schematically illustrating an apparatus for transmitting a signal according to a data symbol channel estimation method according to an embodiment of the present invention.

40 is a block diagram schematically illustrating an apparatus for receiving a signal according to a data symbol channel estimation method according to an embodiment of the present invention.

41 is a block diagram schematically illustrating another signal transmission apparatus of a data symbol channel estimation method according to an embodiment of the present invention.

42 is a block diagram schematically illustrating another signal receiving apparatus of a data symbol channel estimation method according to an embodiment of the present invention.

43 is a view illustrating a structure of a transmission frame according to an embodiment of the present invention.

44 is a diagram illustrating the number of tracking pilots according to a frame according to an embodiment of the present invention.

45 illustrates a frame including a tracking pilot according to an embodiment of the present invention.

46 is a view illustrating a margin according to the frame of FIG. 45 according to an embodiment of the present invention.

47 illustrates another frame including a tracking pilot according to an embodiment of the present invention.

48 is a diagram illustrating a margin according to the frame of FIG. 47 according to an embodiment of the present invention.

49 is a diagram illustrating the number of symbols included in a low density parity check (LDPC) block according to an embodiment of the present invention.

50 is a view illustrating the number of LDPC blocks included in an LDPC frame according to an embodiment of the present invention.

51 is a diagram showing the number of OFDM blocks included in an LDPC frame according to an embodiment of the present invention.

52 is a view illustrating the number of LDPC blocks included in an LDPC frame of another mode according to an embodiment of the present invention.

53 is a view showing the number of OFDM blocks included in an LDPC frame in another mode according to an embodiment of the present invention.

54 illustrates an LDPC frame structure according to an embodiment of the present invention.

55 is a diagram showing the structure of a TPS as an embodiment according to the present invention;

56 illustrates constellation information according to an embodiment of the present invention.

57 illustrates LDPC mode information according to an embodiment according to the present invention.

58 is a diagram illustrating a structure of a TPS including information of FIGS. 58 and 59 according to an embodiment of the present invention.

59 is a diagram illustrating OFDM block index information according to an embodiment of the present invention.

60 is a diagram illustrating a TPS structure including OFDM block index information according to an embodiment of the present invention.

61 is a diagram illustrating LDPC block information according to an embodiment of the present invention.

62 illustrates OFDM block information according to an embodiment of the present invention.

63 is a diagram showing the structure of a TPS including proposed information according to an embodiment of the present invention.

64 is a diagram illustrating preamble period information according to an embodiment of the present invention.

65 is a diagram illustrating a TPS structure including preamble period information according to an embodiment of the present invention.

66 is a diagram illustrating a relationship between a pilot symbol interval and a single frequency network according to an embodiment of the present invention.

67 is a view showing a structure of a pilot symbol according to an embodiment of the present invention.

68 is a block diagram schematically showing another example of a signal transmission apparatus according to an embodiment of the present invention.

69 is a block diagram schematically showing another example of a signal receiving apparatus according to an embodiment of the present invention.

70A and 70B illustrate a proposed frame structure as an embodiment according to the present invention.

71 to 73 illustrate an insertion position of a CP pilot according to each mode according to an embodiment of the present invention.

74A and 74B illustrate a structure of a frame having the same CP pilot position as an embodiment according to the present invention.

75 is a view showing an insertion position of a common CP pilot according to an embodiment of the present invention.

76A to 76C illustrate a structure of a multi-input / output transmission frame according to an embodiment of the present invention.

77 is a diagram illustrating a pseudo random binary (PRBS) generator according to an embodiment of the present invention.

78 is a block diagram schematically showing another example of a signal transmission apparatus according to an embodiment of the present invention.

79 is a block diagram schematically showing another example of a signal receiving apparatus according to an embodiment of the present invention.

80 illustrates a descramble device according to an embodiment of the present invention.

81 is a diagram illustrating the comparison of the number of TPS transmission bits per symbol according to an embodiment of the present invention.

82A is a flowchart illustrating a signal transmission process according to an embodiment of the present invention.

82B is a flowchart illustrating a signal receiving process according to an embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

7800: Outer Encoder 7810: Inner Encoder

7820: First Interleaver 7830: Multiple Mapper

7840: linear precoding unit 7850: second interleaver

7860 frame forming unit 7870 modulator

7880: transmission unit

Claims (12)

Error correcting encoding data; Mapping the error correction coded data to a data symbol; Generating period information in which the first pilot symbol is inserted into a modulation frame; A pilot symbol period in which the first pilot symbol is located only on odd carriers and a data symbol period in which the mapped data symbols are located are formed periodically, and a pilot symbol in which the first pilot symbol is located only in even carriers. Forming a second modulation frame such that a section and a data symbol section in which the mapped data symbol is located are periodically repeated; Modulating the formed first and second modulation frames in an orthogonal frequency multiplexing scheme, respectively; And And transmitting each of the modulated signals. The method of claim 1, At least one of the first modulation frame and the second modulation frame includes a second pilot symbol at a constant carrier position over time. The method of claim 2, And the second pilot symbol is scrambled. Demodulates a signal having a pilot symbol section in which a first pilot symbol is located only in odd carriers and a first modulation frame formed such that the data symbol section in which data symbols are located is periodically repeated, and a pilot symbol in which the first pilot symbol is located only in even carriers Demodulating a signal having a section and a second modulation frame formed such that the data symbol section in which the data symbol is located is periodically repeated; Parsing the first modulated frame and the second modulated frame, respectively; Outputting data symbols included in the first modulation frame and the second modulation frame as one symbol string; Demapping the symbol string; And Error correcting decoding the de-mapped data. The method of claim 4, wherein At least one of the first modulated frame and the second modulated frame includes a second pilot symbol at a constant carrier position over time. The method of claim 5, And the second pilot symbol is scrambled. An error correction encoding unit for error correcting encoding data; A symbol mapper for mapping the error correction coded data to a data symbol; A first modulation frame is formed such that a pilot symbol section in which the first pilot symbol is located and only a data symbol section in which the mapped data symbol is located periodically repeats, and the first pilot symbol is in the first modulation frame. A first frame forming unit to insert period information to be inserted; A second modulation frame is formed such that a pilot symbol period in which the first pilot symbol is located and a data symbol period in which the mapped data symbol is located are periodically repeated only in even carriers, and the first pilot symbol is in the second modulation frame. A second frame forming unit which inserts period information to be inserted; A first modulator for modulating the formed first modulated frame in an orthogonal frequency multiplexing scheme; A second modulator for modulating the formed second modulated frame in an orthogonal frequency multiplexing scheme; A first transmitter to transmit a signal output from the first modulator; And And a second transmitter for transmitting the signal output by the second modulator. The method of claim 7, wherein At least one of the first modulated frame and the second modulated frame includes a second pilot symbol at a constant carrier position over time. The method of claim 8, The second pilot symbol is scrambled signal transmission device. A first demodulation unit configured to demodulate a signal having a pilot symbol section in which a first pilot symbol is located only on an odd carrier and a first modulation frame configured to periodically repeat the data symbol section in which a data symbol is located; A second demodulator for demodulating a signal having a pilot symbol section in which the first pilot symbol is located only on an even carrier and a second modulation frame formed such that the data symbol section in which the data symbol is located is periodically repeated; A first frame parser that parses the first modulated frame; A second frame parser that parses the second modulated frame; A multiple input / output decoder configured to output data symbols included in each of the first modulation frame and the second modulation frame as one symbol string; A symbol demapper for demapping the symbol strings; And And an error correction decoding unit configured to error correct and decode the de-mapped data. The method of claim 10, At least one of the first modulated frame and the second modulated frame includes a second pilot symbol at a constant carrier position over time. The method of claim 11, And the second pilot symbol is scrambled.

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