KR20130106077A - Iterative receiving method and apparatus for performing the same - Google Patents

Abstract

PURPOSE: A repetitive reception method and an apparatus for executing the same are provided to improve reception performance by applying an LLR value calculated in a previous iterative reception process to a derate matching. CONSTITUTION: A transmitting device includes an encoder (110), a scrambler (120), and a modulator (130). The modulator performs a modulation to map scrambled bits with a symbol of a corresponding complex value. A receiving device includes a demodulator (210), a descrambler (220) and a decoder (230). The demodulator includes a symbol detector (211) and a demapper (213). The symbol detector detects a symbol from a signal received from the transmitting device. The demapper produces a first LLR value by using the symbol from the symbol detector. [Reference numerals] (110) Encoder; (111) Channel encoder; (113) Rate matcher; (120) Scrambler; (130) Modulator; (210) Demodulator; (211) Symbol detector; (213) Demapper; (220) Descrambler; (230) Decoder; (231) Derate matcher; (233) Channel decoder

Description

Repetitive reception method and device performing the same {ITERATIVE RECEIVING METHOD AND APPARATUS FOR PERFORMING THE SAME}

The present invention relates to a method for demodulating and decoding a wireless communication system, and more particularly, to an iterative receiving method applicable to a wireless communication system supporting multiple codewords and an apparatus for performing the same.

A transmitting apparatus of a general wireless communication system generates encoded bits by performing encoding and rate matching on a codeword to be transmitted, and then modulates the generated encoded bits and transmits them to the receiving apparatus. Here, rate matching refers to a process of selecting bits to be transmitted through puncturing or repetition according to a predetermined pattern on the encoded bits in order to match the encoded bits to the allocated transmission amount.

The receiver performs demodulation on a signal received from the transmitter, and then performs derate matching to match the size of data transmitted by the transmitter, and then performs decoding.

Meanwhile, in a multi-antenna system such as multiple-input multiple-output (MIMO) that supports spatial multiplexing, nonlinear arithmetic methods such as continuous interference cancellation or parallel interference cancellation are used. Restore the spatially multiplexed received signal.

Continuous interference cancellation is based on the assumption that the spatially multiplexed signals are encoded before multiplexing, and thus, each of the encoded signals is spatially multiplexed and transmitted, which is called multi-codeword transmission.

In the case of multi-codeword transmission, the receiving apparatus demodulates and decodes the received signal, and then, removes the interference between the codewords using the decoded data, and repeatedly demodulates and decodes the signal from which the interference is removed. This improves the reception performance. In this case, when a punctured portion exists in the derate matching process of the received data, the receiving apparatus inputs 0 to the punctured portion to perform derate matching, then decodes and removes interference by using the decoded data. After that, demodulation and decoding are repeatedly performed on the received signal from which the interference has been removed. Here, the receiving apparatus inputs and decodes 0 in the punctured portion even in the process of repeatedly receiving the received signal with interference.

As described above, the conventional receiving apparatus has a disadvantage in that there is a limitation in improving reception performance because the conventional receiving apparatus performs demodulation by inputting all 0s to the punctured portions in the process of repeatedly demodulating and decoding the received signal.

An object of the present invention for overcoming the disadvantages as described above is to provide a repetitive reception method that can improve the reception performance.

In addition, another object of the present invention is to provide a receiving apparatus for performing repeated reception which can improve the reception performance.

An iterative reception method according to an aspect of the present invention for achieving the above object of the present invention, detecting a symbol from a provided signal, and calculating a first Log Likelihood Ratio (LLR) value using the detected symbol; And a matching matching to apply a zero or pre-computed second LLR value according to a predetermined criterion to at least one punctured bit of data configured using the calculated first LLR value. Calculating a second LLR value using the data on which derate matching is performed and performing decoding.

The performing of the derate matching may apply 0 to the at least one punctured bit when the iterative reception method is first performed, and the at least one puncture in the subsequent subsequent reception procedure. The pre-calculated second LLR value calculated during the execution of the previous iterative reception method may be applied to the processed bits according to the preset criteria.

The applying of the pre-calculated second LLR value according to the preset criterion may include determining an L value indicating a range to which the pre-calculated second LLR value is applied among the at least one punctured bit. Determining a threshold for applying the second calculated LLR value based on the determined L value, and comparing the second calculated LLR value with the threshold. And applying a 2 LLR value to the at least one punctured bit, wherein determining the L value may determine the L value based on computational complexity.

In the calculating and decoding of the second LLR value, the second LLR value having a soft decision value may be calculated using a maximum a posteriori probability.

Here, the detecting of the symbol from the provided signal may detect a symbol for a signal transmitted from a transmitting apparatus or a signal provided as a result of a previously performed repetitive reception method.

Here, in the iterative reception method, after calculating and decoding a second LLR value using the derate matching data, regenerating a signal by encoding and modulating the decoded data; The method may further include removing the regenerated signal from a signal transmitted from a transmitting device or a signal from which interference has been removed through a previously performed repetitive receiving method.

In addition, a receiving apparatus according to an aspect of the present invention for achieving another object of the present invention, the detector for detecting a symbol from the provided signal, and calculates a first Log Likelihood (LLR) value using the symbol provided from the detector A demapper and a punctured bit of at least one of the data configured using the calculated first LLR value by applying a 0 or a pre-calculated second LLR value according to a predetermined criterion. After performing rate matching, decoding is performed, and a signal is regenerated using a decoder that calculates a second LLR value using the derate matching data and the decoded data provided from the decoder. And a signal regenerating unit.

Here, the decoder applies 0 to the at least one punctured bit when performing the first repetitive reception, and the at least one puncture in the case of repetitive reception performed after performing the first repetitive reception. The pre-computed second LLR value may be applied to the processed bits according to the predetermined criterion. The decoder may determine an L value representing a range to which the second pre-calculated LLR value is applied among the at least one punctured bit when performing the repeated reception after the first repeated reception. After determining a threshold for applying the pre-calculated second LLR value based on an L value, comparing the second LLR value to the at least one second based on a result of comparing the pre-calculated second LLR value with the threshold value; Applicable to one punctured bit, characterized in that for determining the L value according to the computational complexity.

Here, the signal regeneration unit performs channel encoding on the decoded data provided from the decoding unit, a rate matcher which performs rate matching on the channel encoded data, and modulates the rate matched data. It may include a modulator.

In this case, the receiving apparatus may generate the provided signal by removing the regenerated signal from a buffer storing the signal transmitted from the transmitting apparatus or the provided signal and the signal transmitted from the transmitting apparatus or the signal previously stored in the buffer. It may further include a removal unit.

According to the above-described repetitive reception method and apparatus for performing the same, using a data that has been derate matched in the previous repetitive reception process in the process of performing the repetitive reception by the receiving device receiving the received signal multiplexed with the multiple codewords The calculated soft decision LLR value is adaptively applied to the punctured bits in consideration of the computational complexity.

Therefore, it is possible to reduce the computational complexity of the receiving device, and to apply the LLR value calculated in the previous iterative reception process in derate matching, compared to the conventional iterative reception method of inserting zeros into the punctured bits in every iteration reception process. Receive performance can be improved.

1 is a block diagram illustrating a transmission and reception method of a wireless communication system.
2 is a conceptual diagram illustrating an iterative reception process of processing a spatial multiplex signal received by a receiving apparatus of a wireless communication system supporting multiple codewords.
3 is a flowchart illustrating a repetitive reception method according to an embodiment of the present invention.
4 is a flowchart illustrating the derate matching process of FIG. 3 in more detail.
FIG. 5 is a conceptual diagram illustrating derate matching in a repetitive reception process performed first in the repetitive reception method according to an embodiment of the present invention.
FIG. 6 is a conceptual diagram illustrating derate matching performed in a first and subsequent repeated reception processes in a repeated reception method according to an embodiment of the present invention.
7 is a block diagram illustrating a configuration of a receiving apparatus for performing an iterative receiving process according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

As used herein, a 'transmitter' or 'receiver' may be a mobile station (MS), a mobile terminal (MT), a user terminal, a user equipment (UE), a user terminal (UT: User). Terminal, Wireless Terminal, Access Terminal (AT), Subscriber Unit, Subscriber Station (SS), Wireless Device, Wireless Communication Device, Wireless Transmit / Receive Unit (WTRU) ), Mobile node, mobile, etc., and may be referred to as a base station, a Node-B, an eNode-B, a Base Transceiver System, or an Access Point. It may also be referred to as terms such as an access point, a point, a remote radio head (RRH), a remote radio unit (RRU), a site, a distributed antenna, and the like.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, the same reference numerals will be used for the same constituent elements in the drawings, and redundant explanations for the same constituent elements will be omitted.

1 is a block diagram illustrating a transmission and reception method of a wireless communication system.

Referring to FIG. 1, a wireless communication system may include a transmitting device 100 transmitting a signal and a receiving device 200 receiving a signal transmitted from the transmitting device 100.

The transmitting device 100 may include a coder 110, a scrambler 120, and a modulator 130, and the coder 110 may include a channel encoder 111 and a rate matcher. , 113).

The channel encoder 111 performs turbo coding or convolutional coding on the input data to output the encoded bits, and the rate matcher 113 is an encoding that is an output of the channel encoder 111. The transmitted bits are selected according to the allocated transmission rate by puncturing or repetition of the predetermined bits according to a predetermined pattern.

The scrambler 120 performs scrambling on the rate matched bits using a specific scrambling sequence. Here, scrambling may be performed bit by bit, and inter-cell interference may be suppressed by performing scrambling using different scrambling sequences between neighboring cells.

The modulator 130 performs modulation for mapping the scrambled bits into symbols of corresponding complex values. The modulation scheme may be Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (16QAM), or 64QAM.

As described above, the modulated symbol is mapped to an antenna port and then mapped to an allocated resource block and transmitted through a wireless channel.

The receiving device 200 may include a plurality of antennas, and as described above, receives a signal transmitted through a wireless channel after being processed by the transmitting device 100 to perform demodulation and decoding.

In more detail, the receiver 200 may include a demodulator 210, a descrambler 220, and a decoder 230, and the demodulator 210 may include a symbol detector 211 and a demapper. (demapper, 213). In addition, the decoder 230 may include a derate matcher 231 and a channel decoder 233.

The symbol detector 211 detects a symbol from a signal received from the transmitting apparatus 100 and provides an output in a symbol unit. Here, the symbol detector 211 may perform a minimum mean square error (MMSE) filtering to detect a symbol from the received signal.

The demapper 213 calculates a Log Likelihood Ratio (LLR) value in units of bits using the symbol unit output provided from the symbol detector 211.

The descrambler 220 descrambles the bit unit output provided from the demapper 213 and provides the descrambler 231 to the derate matcher 231. The descrambler 220 may perform descrambling using a pre-assigned sequence.

The derate matcher 231 performs derate matching on the descrambled bits provided from the descrambler 220. When rate matching is performed by the transmitting apparatus 100 in a repetitive method, the derate matcher 231 increases the signal-to-noise ratio (SNR) by adding the received data, and punctures the puncturing method in the transmitting apparatus 100. When rate matching is performed, 0 is inserted into the punctured bit to perform derate matching.

The channel decoder 233 decodes the derate matched data to recover the signal.

On the other ^{hand, 3GPP (3 rd Generation Project Partnership} ) of the LTE (Long Term Evolution) or the recent mobile communication system for LTE-Advanced includes a system to support the transmission multi-code word, which respectively encode a plurality of code words the transmitting device And modulate and transmit the spatial multiplexed signal, and the receiving apparatus receives the transmitted signal after the multiplexed codewords are spatially multiplexed, repeatedly demodulates and decodes the signal to remove interference between the codewords, and removes the interference. Repetitive demodulation and decoding is performed on the word to improve reception performance.

FIG. 2 is a conceptual diagram illustrating an iterative reception process of processing a spatial multiplex signal received by a receiving apparatus of a wireless communication system supporting multiple codewords. FIG. 2 illustrates a continuous interference cancellation technique (SIC) of the received spatial multiplex signal. Demodulation and decoding using

Hereinafter, it is assumed that the spatial multiplexing signal received by the receiving device is rate matched using puncturing.

Referring to FIG. 2, first, a reception apparatus performs a first iterative reception process (S210) of demodulating and decoding one of the received spatial multiplexed signals.

In the first iterative reception process, the reception device performs demodulation, descramble, derate matching, and decoding on the received spatial multiplexed signal, and outputs the decoded first signal. Here, the receiving apparatus configures an LLR value by inserting 0 into a punctured bit during derate matching, and performs decoding using the configured LLR value.

Subsequently, the receiver performs a cyclic redundancy check (CRC) on the first decoded signal to check whether there is an error of the first decoded signal, and if the first decoded signal is normally decoded, Encoding, rate matching, scramble and modulation are performed on the first signal to regenerate it and then remove it from the received signal.

Thereafter, the receiving apparatus performs a second iterative receiving process (S220) for demodulating and decoding the second signal from which the interference is removed from the first signal.

In the second iterative reception process, the reception device demodulates, descrambles, derates, and decodes the second signal from which the interference is removed from the first signal, and outputs the decoded second signal. Here again, the receiving apparatus configures the LLR value by inserting 0 into the punctured portion during the derate matching, and performs decoding using the configured LLR value.

The receiving apparatus checks whether there is an error on the decoded second signal, and if the decoded second signal is normally decoded, the receiving device performs encoding, rate matching, scramble, and modulation on the decoded second signal to firstly decode the second signal. The first signal is removed from the removed received signal.

Thereafter, the receiving apparatus repeats the above process until all spatially multiplexed signals are demodulated and decoded.

As shown in FIG. 2, in a wireless communication system supporting multiple codewords, a receiving apparatus that receives a spatial multiplexed signal decodes all signals after removing interference between the spatial multiplexed signals using an iterative reception technique.

However, in the repeated reception method of the spatial multiplexed signal as shown in FIG. 2, since 0 is inserted and decoded in the punctured part in all the processes of demodulating and decoding each spatial multiplexed signal, the performance of the received signal is improved. There is a limit to this.

In order to solve the above problems, the repeated reception method according to the embodiment of the present invention provides a method for further improving the reception performance of each spatial multiplexed signal.

3 is a flowchart illustrating a repetitive reception method according to an embodiment of the present invention, and illustrates a repetitive reception method when a punctured data is spatially multiplexed and transmitted by a transmitting device. 4 is a flowchart illustrating the derate matching process shown in FIG. 3 in more detail.

Referring to FIGS. 3 and 4, the receiving apparatus first stores a received signal received from the transmitting apparatus or a signal from which interference has been removed through a previous repeating reception process (S301). Here, the received signal is a signal multiplexed by being coded and modulated by a plurality of codewords, respectively, and means a signal first received by the receiving apparatus from the transmitting apparatus. In addition, the signal from which the interference has been removed may be demodulated and decoded by the receiving apparatus through a previous repeated reception process, and then re-coded and modulated by the decoded signal to regenerate the signal, and from the received or received signal. The signal removes the regenerated signal from the signal from which the interference is removed.

Thereafter, the receiving apparatus detects a symbol from the received signal (S303). Here, the receiving device may detect a symbol from the received signal using a minimum mean square error (MMSE).

Hereinafter, the principle of symbol detection using MMSE will be briefly described.

First, the signal received by the receiving device may be expressed as in Equation 1.

In Equation 1, y (m) represents a reception symbol, and x (m) represents a transmission complex value symbol transmitted by a transmitter. In addition, H (m) represents a channel state matrix between each antenna of the transmitting device and each antenna of the receiving device, and w (m) represents a random variable that follows a Gaussian distribution having an average of zero. Indicates.

Linear transform to minimize mean-square error for transmit symbol x (m) in equation (1)

May be expressed as in Equation 2.

In Equation (2)

Denotes an estimated value of the transmission symbol x (m). Equation 2 also indicates that the MMSE filter estimates the transmission symbol.

And a mean squared error value between and the transmission symbol x (m).

Meanwhile, in Equation 1, since the channel state matrix H (m) is linearly independent of all columns (full-column rank),

May be calculated by Equation 3.

In Equation 3,

Denotes the variance of the random variable and I denotes the identity matrix. In calculating Equation 3, the operand of the inverse operation

Can be decomposed into L (m), D (m), L ^* (m), which is the product of three matrices using a modified Gaussian elimination method. Here, L denotes a complex-valued lower triangular matrix having all diagonal elements 1, and D denotes a real-valued diagonal matrix having a real value.

Therefore, Equation 3 may be expressed as Equation 4, and Equation 4 may be obtained through a simultaneous equation.

MMSE weight matrix through the process as described above

Is obtained, it is applied to Equation 2 to estimate the transmission symbol.

And noise variance can be obtained.

Referring to FIG. 3 again, the receiving apparatus detects a symbol from the received signal through the above-described process, and then calculates a first LLR value in units of bits using the detected symbol (S305).

Thereafter, the receiving apparatus performs derate matching by using the calculated first LLR value in units of bits. In this case, the reception apparatus determines whether the modulation and decoding process currently being performed is the first iterative reception process (S307), and if the currently performed process is the first iterative reception process, inputs 0 to the punctured bit. (S309).

Or, if the modulation and decoding process that is currently aquatic is not the first iterative reception process but the signal whose interference is removed from the signal decoded through the previous iterative reception process, the reception device calculates the punctured portion in the previous iterative reception process. The second LLR value is applied (S311). Here, the receiving device may adaptively apply the second LLR value calculated in the previous iterative reception process to the punctured bits.

Referring to FIG. 4, a process of performing derate matching by adaptively using a second LLR value calculated in a previous repeating reception process will be described in detail. In operation S311a, an L value indicating a range to which the second LLR value calculated in FIG. 2 is applied is determined.

Herein, the L value may be set between 0 and 100, and may be determined according to a preset criterion. For example, when the second LLR value calculated in the previous iterative reception process is applied to all the punctured bits, the computational complexity increases, so in order to prevent this, the receiving device sets the L value from 0 to 100 according to the computational complexity. It can be determined within the range of.

For example, when the L value is set to 0, the second LLR value calculated in the previous iteration reception process is not applied to the punctured portion, and when the L value is set to 100, the previous repetition is performed on all punctured bits. The second LLR value calculated in the reception process is applied.

Alternatively, when the L value is set to 50, the second LLR value calculated in the previous iterative reception process may be applied to half of the punctured bits.

In addition, after the reception apparatus determines the L value as described above, the threshold value of the second LLR value for applying the second LLR value calculated in the previous repeated reception process to any punctured bits according to the determined L value Determine (S311b). Here, the threshold may be calculated to have a value corresponding to the determined L value. For example, when the L value is set to 70, the threshold value of the second LLR value is set such that the second LLR value determined in the previous iteration process may be applied to 70% of the punctured bits among the total punctured bits. Can be determined.

Thereafter, the receiving device compares the determined threshold value of the second LLR value with the second LLR value calculated in the previous repeated reception process (S311c), and only when the second LLR value calculated in the previous repeated reception process is less than the threshold value. The second LLR value calculated in the previous iteration reception process is applied to the puncturing portion (S311d), and when the second LLR value calculated in the previous iteration reception process exceeds the threshold value, 0 is applied to the corresponding punctured bits. Enter (S311e).

Alternatively, in addition to the method illustrated in FIG. 4, various methods may be applied to perform reverse puncturing on the punctured portion. For example, the second LLR value calculated in the previous iterative reception process may be simply inserted into all the punctured bits, or the puncturing average of the second and second calculated LLR values. It can also be applied to a given bit.

Alternatively, a result obtained by applying a weight corresponding to the signal-to-noise ratio of the received signal to the second LLR value calculated in the previous repeated reception process may be applied to the punctured bit. As such, when the weight is applied to the second LLR value, the second LLR value to be inserted into the punctured bit may be calculated as LLR = LLR * α. Here, α is a value representing a weight corresponding to the signal-to-noise ratio of the received signal. The lowest value may be set to 0 and may have any constant value of the maximum value. For example, if the signal-to-noise ratio of the received signal is not better than the preset criterion, set α to 0 to input 0 into the punctured part, and repeat if the signal-to-noise ratio of the received signal is better than the preset criterion. The α value may be appropriately set to input the second LLR value calculated in the reception process into the punctured portion.

In addition, as described above, when the average value of the existing second LLR value and the newly calculated second LLR value is applied to the punctured bit, or the puncturing is performed by applying a weight corresponding to the signal-to-noise ratio of the received signal to the second LLR value. In the case of applying to a predetermined bit, a threshold determined according to the range of L values shown in FIG. 4 may be applied to apply only the second LLR value below the threshold to the punctured bit.

Referring to FIG. 3 again, after applying the second LLR value to the punctured portion in the derate matching process as described above, the receiving apparatus performs channel decoding using the derate matched LLR value (S313).

In addition, the reception apparatus calculates a second LLR value to be used for derate matching of a next iterative reception process by using the derate matched LLR value together with channel decoding (S315). Here, the second LLR value may have a soft decision value.

In the process of calculating the second LLR value, a maximum posterior probability (MAP) may be used, and BCJR (Bahl, Cocke, Jelinek and Raviv) algorithm may be used as a representative algorithm. When the second LLR value is calculated using the BCJR algorithm, the LLR value of the puncturing bit with 0 inserted may also be calculated.

Subsequently, the reception apparatus determines whether decoding of all signals included in the spatial multiplexed reception signal is completed (S317), and if decoding of all signals is not completed, use the data decoded in the current iterative reception process. Regenerate the signal (S319). Here, as shown in FIG. 2, the reception apparatus may regenerate a signal by sequentially performing encoding, rate matching, scrambling, and modulation on the decoded signal.

The receiving device removes the regenerated signal from the received signal or the signal from which interference has been removed through a previously performed repetitive receiving process (S321).

Thereafter, the receiving apparatus stores the signal from which the interference is removed in the buffer 710 (S301), and decodes all the spatial multiplexed signals by executing the subsequent iterative receiving process.

FIG. 5 is a conceptual diagram illustrating derate matching in a repetitive reception process performed first in the repetitive reception method according to an embodiment of the present invention.

FIG. 5 (a) shows encoded transmission data before performing rate matching in the transmission apparatus, and FIG. 5 (b) uses puncturing technique for transmission data shown in FIG. 5 (a). It represents the rate-matched data, and through puncturing, data having a size M smaller than the size N of the original transmission data is formed, and the punctured data is transmitted after being subjected to scrambling and modulation. .

FIG. 5C shows received data after performing modulation and descramble on the received signal received by the receiving apparatus, and has the same size as that of the rate matching data shown in FIG. Has

The receiving apparatus inserts 0 into the punctured bit as shown in FIG. 5 (d) in the derate matching step of the first iterative receiving process. Here, the bits other than the punctured bits are applied with a first LLR value obtained by performing demapping, and the derate matched data has the same size as the transmission data shown in FIG.

FIG. 6 is a conceptual diagram illustrating derate matching performed in a first and subsequent repeated reception processes in a repeated reception method according to an embodiment of the present invention.

(A), (b) and (c) of FIG. 6 are the same as each of (a), (b) and (c) of FIG. 5, and therefore, FIGS. 6 (a), (b) and (c) of FIG. Detailed description of c) is omitted.

As described above with reference to FIG. 5, in the derate matching of the first repetitive receiving process according to an embodiment of the present invention, decoding is performed by inserting 0 into punctured bits and simultaneously derate matching. After calculating the second LLR value using the data, the derate matching process performed in the first and subsequent iterative reception processes does not insert 0 into the punctured bit, but as shown in (d) of FIG. 6. Insert the second LLR value calculated in step.

A method of inserting a second LLR value into punctured bits in a derate matching process performed in a first and subsequent iterative matching process may first indicate an application range of the second LLR value as described above with reference to FIG. 4. After determining the L value, a threshold value corresponding to the determined L value may be calculated, and the second LLR value may be adaptively applied to the punctured bits based on the calculated threshold value.

7 is a block diagram illustrating a configuration of a receiving apparatus for performing an iterative receiving process according to an embodiment of the present invention.

Referring to FIG. 7, a receiving apparatus according to an embodiment of the present invention may include a buffer 710, an interference canceling unit 720, a demodulator 730, a descrambler 740, a decoder 750, and a signal regenerator. 760 may include.

The buffer 710 stores the received signal received from the transmitting device in the first iterative receiving process. In addition, after derate matching is performed in the first iterative reception process, a signal from which a regenerated signal is removed from a signal previously stored in the buffer 710 is stored in the buffer 710. For example, in the process of performing the first repetitive reception, the spatial multiplexed reception signal transmitted from the transmitting apparatus is stored in the buffer 710, and in the process of performing the subsequent repetitive reception, the spatial multiplexed received signal or The signal from which the regenerated signal is removed from the signal stored in the buffer 710 in the previous repeated reception process is stored in the buffer 710.

The interference remover 720 removes the signal provided from the signal regenerator 760 from the signal stored in the buffer 710 and provides the demodulator 730. In addition, the interference cancellation unit 720 removes the regenerated signal provided from the signal regeneration unit 760 from the signal stored in the buffer 710, and then removes the regenerated signal from the buffer 710 for the next iterative reception process. ). Here, since the interference canceling unit 720 does not have a regenerating signal provided by the signal regenerating unit 760 before the first signal is decoded, the interference eliminating unit 720 directly provides the received signal stored in the buffer 710 to the demodulating unit 730.

The demodulator 730 may include a detector 731 and a demapper 733, and the detector 731 detects by performing MMSE filtering from a received signal provided from the interference canceller 720 or a signal from which interference is removed. The demapper 733 calculates the first LLR value in bits for the symbol provided from the detector 731.

The descrambler 765 performs descrambling using a sequence previously allocated to the first LLR values in units of bits provided from the demodulator 730, and then provides the descrambler 750 to the decoder 750.

The decoder 750 may include a derate matcher 763, an LLR calculator 735, and a channel decoder 755. The decoder 750 may decode the data provided from the descrambler 765 to decode the decoded data. Output

The derate matcher 763 performs derate matching using a first LLR value in units of descrambled bits. Here, the derate matcher 763 inserts 0 into the punctured bits in the case of the derate matching performed in the first iterative reception process, and in the case of the derate matching performed in the subsequent subsequent reception process. The second LLR value calculated in the previous iterative reception process is input to the adaptively punctured bits.

First, the derate matcher 763 determines an L value indicating a range to apply the second LLR value to the punctured bits in consideration of the computational complexity, and randomly punctures the second LLR value according to the determined L value. After determining the threshold value of the second LLR value to apply to the bits, and compares the determined threshold value and the second LLR value and the second LLR value to the puncturing portion only if the second LLR value is less than the threshold value. Apply.

Alternatively, the derate matcher 763 may simply insert the second LLR value into every punctured bit, and the punctured bit punctures the average of the previously calculated second LLR value and the newly calculated second LLR value. It can also be applied to. In addition, the derate matcher 763 may apply a result value obtained by applying a weight corresponding to the signal-to-noise ratio of the received signal to the second LLR value to the punctured bit.

The LLR calculator 735 calculates a second LLR value for the derate matched data through the derate matcher 763, and then stores the calculated second LLR value in the buffer 710. Here, the LLR calculator 735 may calculate a second LLR value having a soft decision value by using the BCJR algorithm, and the calculated second LLR value is used in derate matching of a subsequent repeated reception process. .

In addition, the channel decoder 755 performs decoding on the derate matched data.

The decoded data is provided to the signal regenerator 760 except for the last repeated reception process. The signal regenerator 760 performs channel encoding, rate matching, scramble, and modulation on the decoded data to decode the decoded data. Regenerate the corresponding signal. The signal regenerator 760 may include a channel encoder 761, a rate matcher 763, a scrambler 765, and a modulator 769.

The signal regenerated through the signal regenerator 760 is provided to the interference canceling unit 720, and the interference providing unit is removed from the signal stored in the buffer 710 and then provided to the demodulator 730, and at the same time the buffer 710. Are stored in.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

100 transmission device 110 coder
111: channel encoder 113: rate matcher
120: scrambler 130: modulator
200: receiver 210: demodulator
211: symbol detector 213: demapper
220: descrambler 230: decoder
231: derate matcher 233: channel decoder
710: buffer 720: interference cancellation unit
730: demodulator 731: detector
733: demapper 740: descrambler
750: decoding unit 751: derate matcher
753: LLR calculator 755: channel decoder
760: signal regeneration unit 761: channel encoder
763: Late matcher 765: scrambler
769: modulator

Claims (14)

Detecting a symbol from the provided signal;
Calculating a first Log Likelihood Ratio (LLR) value using the detected symbols;
A derate matching step of applying a zero or a previously calculated second LLR value according to a predetermined criterion to at least one punctured bit of data configured using the calculated first LLR value; And
Calculating a second LLR value by using derate matching data and performing decoding; The method according to claim 1,
And performing the derate matching comprises applying 0 to the at least one punctured bit when the iterative receiving method is performed for the first time. The method according to claim 1,
The de-rate matching may include performing the first and second LLR values calculated in the process of performing the previous iterative reception method on the at least one punctured bit in the first and subsequent repeated reception processes. Repeated receiving method comprising the step of applying according to. The method according to claim 3,
Applying the pre-calculated second LLR value according to the preset criteria,
Determining an L value representing a range to which the pre-computed second LLR value is to be applied among the at least one punctured bit;
Determining a threshold for applying the pre-calculated second LLR value based on the determined L value; And
And applying the second LLR value to the at least one punctured bit based on a result of comparing the precomputed second LLR value with the threshold value. The method of claim 4,
And determining the L value comprises determining the L value based on computational complexity. The method according to claim 1,
The calculating and decoding of the second LLR value may include calculating the second LLR value having a soft decision value using a maximum a posteriori probability. . The method according to claim 1,
The detecting of the symbol from the provided signal may include detecting a symbol for a signal transmitted from a transmitting device or a signal provided as a result of a previously performed repetitive receiving method. The method according to claim 1,
In the iterative reception method, after calculating a second LLR value using the derate matching data and performing decoding,
Regenerating a signal by performing encoding and modulation on the decoded data; And
And removing the regenerated signal from a signal transmitted from a transmitting apparatus or a signal from which interference has been removed through a previously performed repetitive receiving method. Detector to detect a symbol from a provided signal:
A demapper for calculating a first Log Likelihood (LLR) value using a symbol provided from the detector;
Derate matching is performed by applying a zero or pre-calculated second LLR value according to a predetermined criterion to at least one punctured bit of data configured using the calculated first LLR value. A decoding unit configured to perform decoding and to calculate a second LLR value using the derate matching data; And
And a signal regeneration unit for regenerating a signal using the decoded data provided from the decoding unit. The method of claim 9,
The decoder applies 0 to the at least one punctured bit when performing the first repetitive reception, and performs the at least one punctured repetition after performing the first repetitive reception. And the second pre-calculated LLR value is applied to a bit according to the predetermined criterion. The method of claim 9,
The decoder determines a L value indicating a range to apply the second calculated LLR value among the at least one punctured bit when performing the repeated reception after the first repeated reception, and determines the determined L value. After determining a threshold for applying the second calculated LLR value based on the second LLR value based on a result of comparing the second calculated LLR value with the threshold value. A receiving device, characterized in that applied to the punctured bits. The method of claim 11,
And the decoding unit determines the L value according to a computational complexity. The method of claim 9,
The signal regenerator includes a channel encoder for performing channel coding on the decoded data provided from the decoder, a rate matcher for performing rate matching on the channel encoded data, and a modulator for performing modulation on the rate matched data. Receiving device comprising a. The method of claim 9,
The receiving device includes a buffer for storing a signal transmitted from the transmitting device or the provided signal; And
And an interference canceling unit which generates the provided signal by removing the regenerated signal from a signal transmitted from the transmitter or a signal previously stored in the buffer.

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