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WO2010064399A1 - Dispositif et procédé de communications sans fil - Google Patents

Dispositif et procédé de communications sans fil Download PDF

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Publication number
WO2010064399A1
WO2010064399A1 PCT/JP2009/006483 JP2009006483W WO2010064399A1 WO 2010064399 A1 WO2010064399 A1 WO 2010064399A1 JP 2009006483 W JP2009006483 W JP 2009006483W WO 2010064399 A1 WO2010064399 A1 WO 2010064399A1
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Prior art keywords
bits
bit
systematic
wireless communication
parity
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Ceased
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English (en)
Japanese (ja)
Inventor
吉井勇
岸上高明
栗謙一
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Panasonic Corp
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Panasonic Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0078—Avoidance of errors by organising the transmitted data in a format specifically designed to deal with errors, e.g. location
    • H04L1/0086—Unequal error protection
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/25—Error detection or forward error correction by signal space coding, i.e. adding redundancy in the signal constellation, e.g. Trellis Coded Modulation [TCM]
    • H03M13/255—Error detection or forward error correction by signal space coding, i.e. adding redundancy in the signal constellation, e.g. Trellis Coded Modulation [TCM] with Low Density Parity Check [LDPC] codes
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/63—Joint error correction and other techniques
    • H03M13/6306—Error control coding in combination with Automatic Repeat reQuest [ARQ] and diversity transmission, e.g. coding schemes for the multiple transmission of the same information or the transmission of incremental redundancy
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0056—Systems characterized by the type of code used
    • H04L1/0057—Block codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
    • H04L1/1812—Hybrid protocols; Hybrid automatic repeat request [HARQ]
    • H04L1/1819—Hybrid protocols; Hybrid automatic repeat request [HARQ] with retransmission of additional or different redundancy
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/3405—Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0045—Arrangements at the receiver end
    • H04L1/0047—Decoding adapted to other signal detection operation
    • H04L1/005—Iterative decoding, including iteration between signal detection and decoding operation

Definitions

  • the present invention relates to a wireless communication apparatus and a wireless communication method.
  • ITU-R International Telecommunication Union Radio Radio Communication Sector
  • IMT-Advanced a fourth generation mobile communication system called IMT-Advanced has been studied, and one of error correction codes for realizing a maximum downlink speed of 1 Gbps.
  • LDPC Low-DensityDParity-Check
  • the decoding process can be parallelized, so that the decoding process can be speeded up compared to a turbo code that needs to repeat the decoding process in series.
  • LDPC encoding is performed using a parity check matrix in which a large number of '0's and a small number of' 1's are arranged.
  • the transmitting-side radio communication apparatus encodes a transmission bit string using a check matrix to obtain an LDPC codeword (LDPC) codeword) including systematic bits and parity bits.
  • LDPC LDPC codeword
  • the receiving-side wireless communication apparatus repeatedly receives the likelihood of each bit in the row direction of the check matrix and the column direction of the check matrix, thereby decoding the received data and obtaining a received bit string.
  • the number of '1' included in each column in the parity check matrix is referred to as column weight
  • the number of '1' included in each row in the parity check matrix is referred to as row weight.
  • the parity check matrix can be represented by a Tanner graph that is a bipartite graph composed of rows and columns.
  • each row of the parity check matrix is referred to as a check node
  • each column of the parity check matrix is referred to as a variable node.
  • Each variable node and each check node of the Tanner graph are connected in accordance with the arrangement of “1” in the check matrix, and the wireless communication device on the receiving side repeatedly performs the delivery of likelihood between the connected nodes.
  • the received data is decoded to obtain a received bit string.
  • HARQ Hybrid ARQ
  • the reception-side wireless communication device feeds back an ACK (Acknowledgment) signal to the transmission-side wireless communication device as a response signal if there is no error in the received data and a NACK (Negative Acknowledgment) signal if there is an error.
  • the receiving-side wireless communication device combines the data retransmitted from the transmitting-side wireless communication device and the data received in the past, and decodes the combined data. This improves SINR (SignalNRtoInterference and Noise Ratio) and improves the coding gain, and enables reception data to be decoded with a smaller number of retransmissions than in normal ARQ.
  • SINR Signal Noise Ratio
  • HARQ is IR (Incremental Redundancy) method.
  • IR Insertion Redundancy
  • a codeword is divided into a plurality of redundancy versions (hereinafter referred to as RV) which are retransmission data units, and the plurality of RVs are sequentially transmitted.
  • each RV is configured by extracting coded bits in order from the top of the codeword.
  • Non-Patent Document 1 there is a constellation rearrangement in which signal point arrangement (constellation) in multi-level modulation such as 16QAM and 64QAM is changed (rearranged) for each retransmission (see, for example, Non-Patent Document 1).
  • IEEE 802.16m-08 / 771r1 “Enhanced HARQ scheme with Signal Constellation Rearrangement”, 2008/07
  • the magnitude of the influence of each bit of the LDPC codeword on the decoding performance on the receiving side varies depending on the column weight for each coded bit and the number of RV transmissions. That is, the importance of each coded bit differs depending on the column weight for each coded bit and the number of RV transmissions.
  • an LDPC codeword is simply considered without considering the importance of each encoded bit constituting the LDPC codeword. If the encoded bits are extracted in order from the head of the RV to configure the RV, the encoded bits with higher importance may be mapped to the lower bits, and thus the optimal error rate characteristic may not be obtained.
  • An object of the present invention is to provide a radio communication apparatus and a radio communication method capable of always obtaining optimum error rate characteristics even when constellation rearrangement is used in combination with IR-type HARQ using an LDPC code as an error correction code.
  • the purpose is to provide.
  • the wireless communication apparatus of the present invention extracts each bit of a codeword made up of systematic bits and parity bits obtained by LDPC coding based on a parity check matrix to form a plurality of redundancy versions, and the plurality of redundancy versions are A transmitting-side wireless communication device that sequentially transmits, wherein the codeword is generated by encoding a transmission bit string by the LDPC encoding based on the parity check matrix, and each of the systematic bit and the parity bit Mapping higher importance bits to higher bits of a plurality of bits constituting a symbol, and mapping lower importance bits to lower bits of the plurality of bits constituting the symbol.
  • the systematic bit or the complex adopts a configuration comprising a modulation means for modulating the redundancy version.
  • the wireless communication method of the present invention extracts each bit of a codeword composed of systematic bits and parity bits obtained by LDPC coding based on a parity check matrix to form a plurality of redundancy versions, and the plurality of redundancy versions are A wireless communication method for transmitting sequentially, wherein an encoding step of encoding a transmission bit string by the LDPC encoding based on the parity check matrix to generate the codeword, and importance level in each of the systematic bit and the parity bit By mapping higher bits to higher bits of a plurality of bits constituting a symbol, and mapping lower bits to lower bits of the plurality of bits constituting the symbol, Systematic bit or the plurality A configuration having a modulation step of modulating the redundancy Sea version, the.
  • FIG. 1 is a block configuration diagram of a radio communication device on a transmission side according to Embodiment 1 of the present invention.
  • the figure which shows RV structure which concerns on Embodiment 1 of this invention The figure which shows the transmission process which concerns on Embodiment 1 of this invention.
  • the transmission bit string is input to the LDPC encoding unit 101.
  • the LDPC encoding unit 101 encodes a transmission bit string by LDPC encoding based on a parity check matrix, and generates an LDPC codeword including systematic bits and parity bits. This LDPC codeword is output to interleaving section 102. Also, LDPC encoding section 101 outputs the check matrix to interleaving section 102.
  • the interleaving unit 102 performs an interleaving process for rearranging the order of LDPC code words input from the LDPC encoding unit 101 in accordance with an instruction from the control unit 111. Specifically, interleaving section 102 maps coded bits having higher importance in the systematic bits and parity bits to higher-order bits among a plurality of bits constituting the data symbol, and having lower importance. The LDPC codeword is rearranged so that the coded bits are mapped to the lower bits of the plurality of bits constituting the data symbol.
  • the RV control unit 103 extracts each encoded bit of the LDPC codeword input from the interleaving unit 102 to form a plurality of RVs, and sequentially outputs the RVs to the modulation unit 104.
  • the number of RVs per transmission that is, the number of RVs per output in the RV control unit 103 is obtained by (N ⁇ Rm (1-R)) / (NRV ⁇ R).
  • N is the LDPC code word length
  • Rm is the mother coding rate (coding rate of the LDPC code)
  • R is the coding rate at the first transmission (at the time of the first transmission) input from the control unit 111
  • NRV Indicates the number of bits per 1 RV (that is, the number of bits constituting one RV).
  • the RV control unit 103 stores the LDPC codeword input from the interleaving unit 102. Then, RV control section 103 outputs all systematic bits and any RV included in the LDPC codeword to modulation section 104 in the first transmission (initial transmission). Further, the RV control unit 103 outputs any RV to the modulation unit 104 when the NACK signal is input from the control unit 111, that is, in the second or subsequent transmission (retransmission). In addition, when an ACK signal is input from the control unit 111, the RV control unit 103 stops outputting RV to the modulation unit 104 and discards the stored LDPC codeword.
  • Modulation section 104 modulates the systematic bits and RV input from RV control section 103 in the first transmission (initial transmission), generates a data symbol, and outputs the data symbol to multiplexing section 105.
  • Modulation section 104 modulates RV input from RV control section 103 in the second and subsequent transmissions (retransmission), generates a data symbol, and outputs the data symbol to multiplexing section 105.
  • the modulation unit 104 maps the higher importance bits in the systematic bits and the parity bits constituting the systematic bits or the plurality of RVs to higher bits among the plurality of bits constituting the data symbol. Then, the lower importance bits are mapped to the lower bits of the plurality of bits constituting the data symbol.
  • the multiplexing unit 105 multiplexes the data symbol, the pilot signal, and the control signal input from the control unit 111, and outputs the generated multiplexed signal to the radio transmission unit 106.
  • the wireless transmission unit 106 performs transmission processing such as D / A conversion, amplification and up-conversion on the multiplexed signal, and transmits the signal from the antenna 107 to the reception-side wireless communication device.
  • the radio receiving unit 108 receives a control signal transmitted from the radio communication apparatus on the receiving side via the antenna 107, and performs reception processing such as down-conversion and A / D conversion on the control signal and demodulates it. Output to the unit 109.
  • This control signal includes a CQI (Channel Quality Indicator) and a response signal (ACK signal or NACK signal) generated by the wireless communication device on the receiving side.
  • the demodulation unit 109 demodulates the control signal and outputs it to the decoding unit 110.
  • the decoding unit 110 decodes the control signal and outputs the CQI and response signal included in the control signal to the control unit 111.
  • the control unit 111 controls the coding rate after RV control according to the CQI. Then, the control unit 111 outputs a control signal indicating the determined coding rate to the RV control unit 103 and the multiplexing unit 105. The control unit 111 determines the coding rate after RV control to be a higher coding rate as the input CQI is a CQI corresponding to higher channel quality. Further, the control unit 111 outputs a response signal input from the decoding unit 110 to the RV control unit 103.
  • control unit 111 instructs the interleaving unit 102 to rearrange the order of the LDPC codewords input from the LDPC encoding unit 101. Specifically, the control unit 111 maps, to the interleaving unit 102, coded bits having higher importance in the systematic bits and the parity bits to higher bits among a plurality of bits constituting the data symbol. And instructing the LDPC codewords to be rearranged in the order in which encoded bits of lower importance are mapped to lower bits among a plurality of bits constituting a data symbol.
  • a receiving-side radio communication apparatus receives the multiplexed signal transmitted from the transmitting-side radio communication apparatus 100 (FIG. 1), and separates the multiplexed signal into a data symbol, a pilot signal, and a control signal. . Then, at the time of receiving the first transmission data (systematic bit and RV), the receiving-side wireless communication apparatus has padding bits with a log-likelihood ratio of 0 at the positions of encoded bits other than the encoded bits included in the received data. , And save the obtained data.
  • the reception-side wireless communication apparatus performs deinterleaving processing for rearranging the obtained data using the same interleave pattern as that used by the interleaving unit 102 of the transmission-side wireless communication apparatus 100.
  • the receiving-side wireless communication apparatus obtains a decoded bit string (received bit string) by LDPC decoding the received data after the deinterleaving process.
  • the receiving-side wireless communication device when receiving the second transmission data (RV), the receiving-side wireless communication device combines the received data and the stored data, stores the obtained data, and performs LDPC decoding.
  • the radio communication device on the receiving side performs error detection on the received bit string and generates a response signal (ACK signal or NACK signal). Also, the receiving-side wireless communication apparatus estimates channel quality (for example, SINR) using the pilot signal, and generates CQI corresponding to the estimated SINR. Then, the wireless communication device on the reception side transmits a control signal including the response signal and the CQI to the wireless communication device 100 on the transmission side.
  • channel quality for example, SINR
  • one symbol is composed of 4 bits, and the constellation (signal point arrangement) is as shown in FIG. That is, a symbol obtained using 16QAM is mapped to one of the 16 signal points shown in FIG.
  • 4 bits constituting one symbol are represented as (i 1 , q 1 , i 2 , q 2 ).
  • the determination boundary line of the upper 2 bits (i 1 , q 1 ) is the I axis and Q axis shown in FIG.
  • the width of the determination boundary of the lower 2 bits (i 2 , q 2 ) is narrower than the width of the determination boundary of the upper 2 bits (i 1 , q 1 ). For this reason, high likelihood is obtained with the upper 2 bits (i 1 , q 1 ), whereas only low likelihood is obtained with the lower 2 bits (i 2 , q 2 ). That is, the lower 2 bits are more susceptible to bit errors than the upper 2 bits.
  • (0, 0) has a high likelihood because it is mapped to the upper 2 bits at the previous transmission, and has a lower likelihood because it is mapped to the lower 2 bits at the time of retransmission.
  • (1, 1) has a low likelihood because it is mapped to the lower 2 bits at the previous transmission, and has a higher likelihood because it is mapped to the upper 2 bits at the time of retransmission. In this way, by applying the constellation rearrangement to HARQ, the likelihood can be improved evenly in all the bits constituting one symbol.
  • the radio communication device on the receiving side exchanges likelihoods between variable nodes (encoded bits) via check nodes of the Tanner graph corresponding to the check matrix, and each variable node (code The received data is decoded by repeatedly updating the likelihood of the bit.
  • the number of check nodes connected to each variable node (encoded bit) is equal to the column weight of each column of the parity check matrix. Therefore, the higher the column weight, the greater the number of times of likelihood transfer with other encoded bits, and the greater the effect of improving the likelihood. That is, the higher the column weight, the higher the importance.
  • coded bits (variable nodes) with smaller column weights have fewer likelihood passes with other coded bits. That is, the encoded bit with the smaller column weight has a smaller likelihood of receiving, and therefore the effect of updating the likelihood for the encoded bit is smaller. Therefore, when RV is further transmitted after all the parity bits included in the LDPC codeword are transmitted, the encoded bits with smaller column weights are preferentially retransmitted to compensate for the likelihood. It is better to increase the likelihood of bits. That is, when RV is further transmitted after all the parity bits included in the LDPC codeword are transmitted, the encoded bits having the smaller column weight are more important.
  • the coded bits having a large column weight are coded bits that have a greater influence on the decoding performance on the receiving side, that is, important bits.
  • the coded bits having a small column weight become coded bits that have a great influence on the decoding performance on the receiving side, that is, important bits.
  • modulation section 104 performs systematic bits and parity bits, respectively, until all parity bits included in the LDPC codeword are transmitted (that is, until transmission with a mother coding rate or less). , The systematic bits with higher column weights or the parity bits with higher column weights are mapped to the upper bits of the multiple bits making up the data symbol, and the systematic bits or column weights with lower column weights are smaller Map parity bits to lower bits. Further, modulation section 104, when RV is further transmitted after all parity bits included in the LDPC codeword are transmitted (that is, when transmitted at a coding rate larger than the mother coding rate), column weights Map the systematic bits with lower to the upper bits and map the systematic bits with higher column weights to the lower bits. Thereby, the modulation
  • the transmission bit string length is 16 bits
  • the mother coding rate Rm is 1/3
  • the bit number NRV per RV is 8 bits
  • the coding rate R determined by the control unit 111 is 2/3.
  • the RV control unit 103 obtains the number of RVs per output from (N ⁇ Rm (1-R)) / (NRV ⁇ R), and outputs one RV to the modulation unit 104 with one output. To do.
  • the RV control unit 103 configures each RV with 8 encoded bits, and the first transmission data (initial transmission data) includes 16 systematic bits and 8 bits.
  • a 24-bit LDPC codeword containing the constructed RV is obtained.
  • the modulation scheme in the modulation unit 104 is 16QAM.
  • the modulation unit 104 receives four bits constituting each data symbol successively from the most significant bit (Most Significant bit: MSB) to the least significant bit (Least Significant bit: LSB).
  • the interleaving unit 102 rearranges the systematic bits S1 to S16 and the parity bits P1 to P32 of the LDPC codeword (uppermost stage in FIG. 3) input from the LDPC encoding unit 101 in descending order of column weight. Specifically, as shown in FIG. 3, interleaving section 102 rearranges systematic bits S1 to S16 into S1 to S4, S7, S8, S11, S12, S5, S6, S9, S10, and S13 to S16. . The same applies to the parity bits P1 to P32.
  • interleaving section 102 sequentially sorts the systematic bits (systematic bits in order 1 to 16 after rearrangement shown in FIG. 3) from the head (systematic bit S1 in order 1 after rearrangement).
  • the systematic bits are rearranged so that they are mapped to the upper bits of each data symbol and mapped to the lower bits of each data symbol in order from the end (order 16 systematic bit S16 after rearrangement). That is, as shown in FIG. 3, interleaving section 102 sequentially maps the systematic bits of order 1 to 8 after rearrangement to the upper bits, and the systematic bits of order 16 to 9 after the rearrangement.
  • the systematic bits S1 to S16 are rearranged so that they are sequentially mapped to the bits.
  • the number of bits (NRV) constituting one RV is 8 bits. Therefore, as shown in FIG. 3, the RV control unit 103 uses 8 bits of parity bits in a 48-bit LDPC codeword including 16 systematic bits S1 to S16 and 32 bits of parity bits P1 to P32. RV1 to RV4 are configured by extraction.
  • the RV control unit 103 outputs the systematic bits S1 to S16 and RV1 to the modulation unit 104 in the first transmission (initial transmission), and performs the second transmission (first retransmission). Then, RV2 is output to the modulation section 104, RV3 is output to the modulation section 104 in the third transmission (second retransmission), and RV4 is output to the modulation section 104 in the fourth transmission (third retransmission).
  • the coding rate R in each transmission at this time is 2/3 in the first transmission, 1/2 in the second transmission, and 2/5 in the third transmission, as shown in FIG. In the second transmission, it becomes 1/3, which is the same as the mother coding rate Rm.
  • the modulation unit 104 converts the systematic bits S1 to S4, S7, S8, S11, and S12 having the larger column weights to each data as shown in FIG.
  • the 4 bits (i 1 , q 1 , i 2 , q 2 ) constituting the symbol are mapped to the upper 2 bits (i 1 , q 1 ).
  • the modulation unit 104 converts the systematic bits S5, S6, S9, S10, and S13 to S16 having smaller column weights into four bits (i 1 , q 1 , i 2, q 2) is mapped to the lower 2 bits (i 2, q 2) of the.
  • the RV control unit 103 is as shown in the bottom row of FIG. Further, in the systematic bits of the order 1 to 16 after the rearrangement, they are mapped to the upper bits of each data symbol in order from the end (the systematic bit S16 of the order 16 after the rearrangement), and the head (after the rearrangement). The systematic bits are rearranged so that they are mapped to the lower bits of each data symbol in order from the systematic bit S1) of order 1.
  • the RV control unit 103 extracts RMB5 and RV6 by extracting the rearranged systematic bits by 8 bits from the head.
  • the RV control unit 103 outputs RV5 to the modulation unit 104 in the fifth transmission (fourth retransmission), and RV6 in the sixth transmission (fifth retransmission). To 104.
  • the coding rate R in each transmission is 2/7 in the fifth transmission and 1/4 in the sixth transmission.
  • RV6 transmitted at the sixth transmission (fifth retransmission) shown in FIG.
  • the modulation unit 104 performs column weighting as illustrated in FIG. Systematic bits S5, S6, S9, S10, S13 to S16 having a smaller value than the upper 2 bits (i 1 , q 2 ) of the 4 bits (i 1 , q 1 , i 2 , q 2 ) constituting each data symbol Mapping to 1 ). Further, as shown in FIG. 3, the modulation unit 104 converts systematic bits S1 to S4, S7S8, S11, and S12 having larger column weights into four bits (i 1 , q 1 , i 2) constituting each data symbol. , Q 2 ) to the lower 2 bits (i 2 , q 2 ).
  • Encoded bits other than the important bits are replaced.
  • encoded bits having higher column weights systematic bits or parity bits
  • encoded bits having lower column weights Becomes an unimportant bit.
  • systematic bits with smaller column weights become important bits, and systematic bits with higher column weights become non-important bits.
  • the modulation unit 104 maps the significant bits to the upper bits at any number of transmissions, so that before and after all the parity bits are transmitted, the encoded bits and lower bits are mapped to the upper bits.
  • the coded bits to be mapped are interchanged. That is, the modulation unit 104 automatically maps the important bits to the upper bits at any number of transmissions, thereby automatically obtaining the effect of constellation rearrangement. Therefore, since all systematic bits S1 to S16 are mapped to the upper 2 bits and the lower 2 bits by constellation rearrangement, the likelihood of each bit can be improved uniformly. That is, the error rate characteristic of each bit can be improved uniformly.
  • the radio communication device on the transmission side maps the important bit to the upper bit among the plurality of bits constituting the data symbol.
  • the receiving-side wireless communication apparatus is less likely to cause bit errors of coded bits having a higher column weight until all parity bits are transmitted.
  • bit errors of encoded bits with smaller column weights are less likely to occur. That is, in the radio communication device on the receiving side, the probability of receiving coded bits that greatly contribute to the likelihood improvement can be increased without error, so that the effect of the likelihood improvement can be improved.
  • the likelihoods of all the coded bits can be made uniform with high likelihood by constellation rearrangement. Therefore, according to the present embodiment, even when constellation rearrangement is used in combination with IR-type HARQ using an LDPC code as an error correction code, an optimal error rate characteristic can always be obtained.
  • LDPC codewords are grouped into groups of transmission units (that is, RV units), and important bits of LDPC codewords are mapped to upper bits of data symbols in units of groups.
  • modulation section 104 (FIG. 1) of radio communication apparatus 100 on the transmission side has a plurality of coded bits of LDPC codewords grouped in the output order of LDPC coding section 101. In each of the groups, encoded bits with higher importance are mapped to upper bits, and encoded bits with lower importance are mapped to lower bits.
  • the transmission bit string length is 16 bits
  • the mother coding rate Rm is 1/3
  • the number of bits NRV per RV is 8 bits
  • the coding rate R determined by the control unit 111 is the same as in the first embodiment. Is 2/3.
  • the RV control unit 103 outputs one RV to the modulation unit 104 with one output.
  • the RV control unit 103 configures each RV with 8 bits, and includes 16 systematic bits and 8 bits as the first transmission data (initial transmission data).
  • a 24-bit LDPC codeword including RV is obtained.
  • the modulation scheme in modulation section 104 is 16QAM.
  • the number of encoded bits for each of a plurality of groups configured by grouping LDPC codewords is 8 bits, which is the same as the number of bits NRV per 1 RV.
  • the interleaving unit 102 groups the systematic bits S1 to S16 and the parity bits P1 to P32 of the LDPC codeword (uppermost stage in FIG. 5) in the order of output from the LDPC encoding unit 101, thereby forming a plurality of groups. Specifically, as shown in FIG. 5, interleaving section 102 groups 48-bit LDPC codewords into 8 bits that are transmission units (that is, RV units), and S1 to S8, S9 to S16, A plurality of groups each including P1 to P8, P9 to P16, P17 to P24, and P25 to P32 are formed.
  • interleaving section 102 rearranges each encoded bit in descending order of the column weight in each of the plurality of groups, as in the first embodiment. Further, interleaving section 102 performs coding (order 1 code after reordering) at the beginning (reordered systematic bits or parity bits in order 1 to 8 shown in FIG. 5) of each group. The encoded bits are rearranged so as to be mapped to the upper bits of the data symbol in order from the encoded bit) and to the lower bits of the data symbol in order from the end (the encoded bit of order 8 after the rearrangement). That is, as shown in FIG.
  • interleaving section 102 sequentially maps the encoded bits of order 1 to 4 after rearrangement to the upper bits, and encodes the encoded bits of order 8 to 5 after the rearrangement.
  • the encoded bits of each group are rearranged so that they are mapped to the bits in order.
  • the systematic bits S1 to S4, S7, S8, S5 and S6 of the order 1 to 8 after rearrangement are S1, S2, S6, S5, S3, S4, S8. , S7.
  • the RV control unit 103 Since the number of bits (NRV) constituting one RV is 8 bits, the RV control unit 103 has 8 bits of parity bits in a 48-bit LDPC codeword, as shown in FIG. RV1 to RV4 are configured by extracting in groups.
  • modulation section 104 has systematic bits or column weights with larger column weights in each of a plurality of groups, as shown in FIG.
  • the larger parity bit is mapped to the upper 2 bits (i 1 , q 1 ) among the 4 bits (i 1 , q 1 , i 2 , q 2 ) constituting each data symbol.
  • the modulation unit 104 converts the systematic bits having a smaller column weight or the parity bits having a smaller column weight into four bits (i 1 , q 1 , i 2 , q 2 ) is mapped to the lower 2 bits (i 2 , q 2 ).
  • the RV control unit 103 when RV is further transmitted after all the parity bits P1 to P32 are transmitted, the RV control unit 103 performs the encoding in the order 8 to 5 after the rearrangement as shown in the bottom of FIG.
  • the encoded bits of each group are rearranged so that the bits are mapped in order to the upper bits, and the encoded bits in order 1 to 4 after the rearrangement are sequentially mapped to the lower bits.
  • the RV control unit 103 extracts RMB5 and RV6 by extracting 8 systematic bits after rearrangement.
  • modulation section 104 uses systematic bits S5, S6, S9, S10, S13 to S16 having smaller column weights in RV5 and RV6, as in the first embodiment.
  • the data symbols are mapped to the upper 2 bits (i 1 , q 1 ) out of 4 bits (i 1 , q 1 , i 2 , q 2 ).
  • the modulation unit 104 converts the systematic bits S1 to S4, S7, S8, S11, and S12 having larger column weights into four bits (i 1 , q 1 , i 2, q 2) is mapped to the lower 2 bits (i 2, q 2) of the.
  • the modulation unit 104 can map the significant bits to the upper bits at any transmission time, so that the effect of constellation rearrangement can be obtained, and the likelihood of all the encoded bits is increased. It can be aligned with high likelihood.
  • the transmitting-side radio communication apparatus groups each bit of the LDPC codeword for each transmission unit (RV unit) according to the output order of LDPC encoding. For this reason, the radio communication device on the transmission side can sequentially perform transmission processing in units of RV configured in the order of output of the encoded bits. Therefore, even when the LDPC codeword length is very long, it is possible to easily configure an RV in consideration of the optimum error rate characteristics.
  • the present invention is implemented by an FDD (Frequency Division Duplex) system has been described as an example.
  • the present invention can also be implemented by a TDD (Time Division Division Duplex) system.
  • the transmitting-side radio communication apparatus 100 since the correlation between the uplink channel characteristics and the downlink channel characteristics is very high, the transmitting-side radio communication apparatus 100 receives signals using signals from the receiving-side radio communication apparatus. The reception quality in the wireless communication device on the side can be estimated. Therefore, in the case of a TDD system, the wireless communication device on the reception side may estimate the channel quality in the wireless communication device 100 on the transmission side without reporting the channel quality by CQI.
  • interleaving section 102 rearranges each bit of the LDPC codeword according to the column weight, and RV control section 103 extracts each rearranged bit to configure RV.
  • the process of rearranging each bit of the LDPC codeword in the interleaving unit 102 may be omitted, and the RV control unit 103 may configure the RV by directly extracting each bit according to the column weight.
  • the coding rate set by the control unit 111 of the wireless communication device 100 on the transmission side is not limited to that set according to the line quality, but may be fixed.
  • SINR is estimated as channel quality, but SNR, SIR, CINR, received power, interference power, bit error rate, throughput, MCS (Modulation and Coding scheme) that can achieve a predetermined error rate, etc. May be estimated as the channel quality.
  • the CQI may be expressed as CSI (Channel State Information).
  • the transmission-side radio communication apparatus 100 can be provided in the radio communication base station apparatus, and the reception-side radio communication apparatus can be provided in the radio communication mobile station apparatus. Further, the radio communication device 100 on the transmission side may be provided in the radio communication mobile station device, and the radio communication device on the reception side may be provided in the radio communication base station device. Thereby, it is possible to realize a radio communication base station apparatus and a radio communication mobile station apparatus that exhibit the same operations and effects as described above.
  • the radio communication mobile station apparatus may be referred to as UE, and the radio communication base station apparatus may be referred to as Node B.
  • each functional block used in the description of the above embodiment is typically realized as an LSI which is an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include a part or all of them.
  • the name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.
  • the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible.
  • An FPGA Field Programmable Gate Array
  • a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.
  • the present invention can be applied to a mobile communication system or the like.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Probability & Statistics with Applications (AREA)
  • Theoretical Computer Science (AREA)
  • Error Detection And Correction (AREA)

Abstract

L'invention concerne un dispositif de communications sans fil qui permet d'obtenir des caractéristiques de taux d'erreur optimisées à tout moment même  en cas d'utilisation d'un réagencement de constellations conjointement avec IR-HARQ dans un système IR qui utilise un code LDPC pour code de correction d'erreur. Dans le dispositif de communications sans fil, une unité de codage LDPC (101) code une chaîne binaire de transmission utilisant un codage LDPC basé sur une matrice de vérification pour générer un mot de code, et une unité de modulation (104) module des bits systématiques ou une pluralité de versions redondantes par mappage des bits systématiques et de bits de parité qui présentent une priorité élevée par rapport à des bits de poids fort de la pluralité de bits constituant un symbole de données, et mappage des bits systématiques et de bits de parité qui présentent une faible priorité par rapport aux bits de poids faible de la pluralité de bits constituant un symbole de données.
PCT/JP2009/006483 2008-12-01 2009-11-30 Dispositif et procédé de communications sans fil Ceased WO2010064399A1 (fr)

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JP2008-306666 2008-12-01

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002199037A (ja) * 2000-12-27 2002-07-12 Matsushita Electric Ind Co Ltd 無線送信装置、無線受信装置および多値変調通信システム
WO2007029734A1 (fr) * 2005-09-06 2007-03-15 Kddi Corporation Système et procédé de transmission de données
WO2008132813A1 (fr) * 2007-04-17 2008-11-06 Panasonic Corporation Dispositif de communication radio et procédé de communication radio

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002199037A (ja) * 2000-12-27 2002-07-12 Matsushita Electric Ind Co Ltd 無線送信装置、無線受信装置および多値変調通信システム
WO2007029734A1 (fr) * 2005-09-06 2007-03-15 Kddi Corporation Système et procédé de transmission de données
WO2008132813A1 (fr) * 2007-04-17 2008-11-06 Panasonic Corporation Dispositif de communication radio et procédé de communication radio

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