EP2057772A1 - Procédé de transmission de données utilisant un mappage sur une constellation de signaux - Google Patents

Procédé de transmission de données utilisant un mappage sur une constellation de signaux

Info

Publication number
EP2057772A1
EP2057772A1 EP07807979A EP07807979A EP2057772A1 EP 2057772 A1 EP2057772 A1 EP 2057772A1 EP 07807979 A EP07807979 A EP 07807979A EP 07807979 A EP07807979 A EP 07807979A EP 2057772 A1 EP2057772 A1 EP 2057772A1
Authority
EP
European Patent Office
Prior art keywords
transmission
data
symbols
symbol
bit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP07807979A
Other languages
German (de)
English (en)
Other versions
EP2057772A4 (fr
Inventor
Hyung Ho Park
Bin Chul Ihm
Min Seok Oh
Doo Hyun Sung
Jae Hoon Chung
Sung Ho Moon
Jin Soo Choi
Ki Hyoung Cho
Seung Hyun Kang
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LG Electronics Inc
Original Assignee
LG Electronics Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR1020060115820A external-priority patent/KR101208543B1/ko
Application filed by LG Electronics Inc filed Critical LG Electronics Inc
Publication of EP2057772A1 publication Critical patent/EP2057772A1/fr
Publication of EP2057772A4 publication Critical patent/EP2057772A4/fr
Ceased legal-status Critical Current

Links

Classifications

    • 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]
    • 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
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
    • H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes
    • 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
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0006—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission format
    • 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
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
    • H04L1/0026—Transmission of channel quality indication
    • 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
    • H04L1/02—Arrangements for detecting or preventing errors in the information received by diversity reception
    • H04L1/06—Arrangements for detecting or preventing errors in the information received by diversity reception using space diversity
    • H04L1/0606—Space-frequency coding
    • 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
    • H04L1/02—Arrangements for detecting or preventing errors in the information received by diversity reception
    • H04L1/06—Arrangements for detecting or preventing errors in the information received by diversity reception using space diversity
    • H04L1/0618—Space-time coding
    • H04L1/0637—Properties of the code
    • H04L1/0643—Properties of the code 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
    • H04L1/1867—Arrangements specially adapted for the transmitter end
    • H04L1/1893—Physical mapping arrangements

Definitions

  • Examples of the diversity technique include frequency diversity, time diversity and spatial diversity.
  • the spatial diversity employs multiple transmit antennas.
  • ISI inter-symbol interference
  • STC Space-time code
  • ML maximum likelihood
  • a minimum means- square error (MMSE) receiver can implement easier than the ML receiver.
  • MMSE minimum means- square error
  • the MMSE receiver has to store channel information in a buffer since the STC is decoded by using cumulative combining technique. Also, the performance of the STC can be deteriorated in time- varying channel highly influenced by Doppler effect.
  • the HARQ can be classified into Type 1, Type II, and Type III.
  • Type I Type II
  • Type II Type II
  • Type III Type III
  • HARQ a receiver discard s data from which an error is detected and a transmitter retransmits the data.
  • a receiver does not discard data from which an error is detected.
  • the receiver combines the erroneous data with re-transmitted data.
  • the erroneous data and the re-transmitted data may have different code rates or modulation schemes.
  • a transmitter re-transmits data which is self- decodable.
  • the HARQ can be classified into chase combining and IR (Incremental
  • the chase combining is a modified scheme of Type I HARQ.
  • a receiver does not discard data from which an error is detected and combines the erroneous data with re-transmitted data.
  • chase combining the erroneous data and the re-transmitted includes same information bits.
  • a transmitter re-transmits data which incrementally includes additional redundant information.
  • the HARQ employs re-transmission of data, there is no spatial diversity gain when one transmit antenna is used. In multiple antenna system, the HARQ can obtain spatial diversity gain to enhance reliability of data. However, in slow fading the HARQ may have no gain since channel state is almost not varied when re-transmission occurs. In fast fading, ISI may be caused due to the spatial diversity.
  • Another advantage of some aspects of the invention is that it provides a data transmission method using an HARQ in which data symbol is re-transmitted after remapped on signal constellation.
  • a data transmission method including performing a bit remapping on signal constellation to form a plurality of data symbols, modulating the plurality of data symbols, and transmitting the modulated data symbols.
  • a data transmission method using an HARQ including transmitting a transmission symbol, receiving a re-transmission request signal for the transmission symbol, and transmitting a re-transmission symbol obtained by remapping the transmission symbol in response to the re-transmission request signal.
  • HARQ Hybrid Automatic Repeat Request
  • a transmitter including an antenna, an adaptive mapper configured to rearranges a plurality of data symbols by bits on a signal constellation, and a modulator configured to modulate the rearranged data symbols to form transmission symbols to be transmitted through the antenna.
  • FIG. 2 is a signal constellation diagram illustrating a bit error rate corresponding to a constellation mapping.
  • FIG. 3 is a diagram illustrating an inter-symbol distance in the signal constellation diagram of FIG. 2.
  • FIG. 10 is a diagram illustrating an example of an adaptive mapping.
  • FIG. 16 is a flowchart illustrating a data transmission method using the communication system shown in FIG. 15.
  • FIG. 17 is a diagram illustrating an arrangement of re-transmission symbols according to an embodiment of the invention.
  • FIG. 18 is a diagram illustrating an arrangement of re-transmission symbols according to another embodiment of the invention.
  • FIG. 19 is a diagram illustrating an arrangement of re-transmission symbols according to still another embodiment of the invention.
  • FIG. 20 is a diagram illustrating an arrangement of re-transmission symbols according to still another embodiment of the invention.
  • FIG. 21 is a diagram illustrating an arrangement of re-transmission symbols according to still another embodiment of the invention.
  • FIG. 22 is a diagram illustrating a data transmission method according to another embodiment of the invention.
  • FIG. 23 is a graph illustrating a simulation result by SNR VS. BER (Bit Error Rate).
  • FIG. 26 is a graph illustrating a simulation result by SNR VS. FER.
  • FIG. 27 is a block diagram illustrating a transmitter according to another embodiment of the invention.
  • FIG. 28 is a diagram illustrating a re-transmission symbol in the transmitter shown in FIG. 27
  • FIG. 29 is a block diagram illustrating a transmitter according to another embodiment of the invention.
  • FIG. 30 is a diagram illustrating a transmitter and a re-transmission symbol according to another embodiment of the invention.
  • FIG. 31 is a block diagram illustrating a communication system according to another embodiment of the invention.
  • FIG. 32 is a flowchart illustrating a hybrid automatic repeat request (HARQ) method using the communication system shown in FIG. 31.
  • FIG. HARQ hybrid automatic repeat request
  • FIG. 48 is a block diagram illustrating a transmitter using an OFDM.
  • FIG. 60 illustrates a simulation result in which the BSA schemes are compared with each other at a user equipment speed of 30 km/h.
  • FIG. 64 is a graph illustrating a simulation result using the mapping method shown in FIG. 63 by SNR VS. BER.
  • a communication system may have a single transmit antenna as well as multiple transmit antennas.
  • the communication system may be one of a multiple-input multiple-output (MIMO) system, a multiple-input single-output (MISO) system, a single-input single-output (SISO) system, and a single-input multiple-output (SIMO) system.
  • MIMO multiple-input multiple-output
  • MISO multiple-input single-output
  • SISO single-input single-output
  • SIMO single-input multiple-output
  • the MIMO system uses multiple transmit antennas and multiple receiving antennas.
  • the MISO system uses multiple transmit antennas and a single receiving antenna.
  • the SISO system uses a single transmit antenna and a single receiving antenna.
  • the SIMO system uses a single transmit antenna and multiple receiving antennas.
  • a signal constellation is composed of a set of two partitions.
  • the signal constellation can be divided into first and second partitions in which the bit values at one position are equal to each other and the bit values at the other positions are different from each other.
  • the signal constellation can be divided into two partitions of which only the first bit values from the left end are different from each other, two partitions of which only the second bit values are different from each other, two partitions of which only the third bit values are different from each other, and two partitions of which only the fourth bit values are different from each other.
  • the sets of partitions are different depending on the bit positions, which is because inter-symbol distances are different.
  • One symbol composed of at least one bit has an error rate varying depending on the bit positions. This fact can be utilized in a multiple antenna system.
  • the symbol is rearranged and transmitted in consideration of a spatial diversity gain using the multiple antennas and a time diversity gain using a time delay, it is possible to obtain an additional diversity gain. That is, by transmitting plural bits constituting one symbol through paths temporally and/or spatially different from the original path, it is possible to enhance the channel reliability of the bits constituting a data symbol as a whole.
  • S is constructed by swapping bit b with bit b of S and swa r p r ping ° bit b 4 with bit b 8 of S 2 .
  • S 1 is constructed by J swa r p r ping ° bit b 10 with bit b 6 of
  • S and swapping bit b with bit b of S are constructed by swapping bit b with bit b of S and swapping bit b with bit b of S .
  • S is constructed by
  • the adaptive mapper performs a remapping process on the bits constituting the signal constellation in different data symbols.
  • the remapping process means that the bits of the data symbols are swapped and/or replaced, but does not necessarily mean that the data symbols are mapped and a new mapping process is performed thereon.
  • the optimal mapping method of swapping and replacing the bits of the symbols by the use of a signal constellation rearranging method can be desired depending on the number of antennas, the modulation order, the time slots, and the channel conditions.
  • the diversity gain is obtained by averagely enhancing the channel reliability of the bits of the data symbols. That is, by performing the bit mapping on the signal constellation every transmission in consideration of the spatial and temporal multiplexing, it is possible to secure the mapping diversity due to the variation in channel.
  • FIG. 5 is a diagram illustrating another example of the adaptive mapping scheme.
  • the left side shows a conventional mapping scheme and the right side shows an adaptive mapping scheme.
  • FIG. 6 is a diagram illustrating an example of an adaptive mapping scheme on
  • S and S are complex conjugates of S and S .
  • the transmission symbols S and S are temporally or spatially rearranged and the result thereof is transmitted through the STBC.
  • the left side shows a conventional mapping scheme and the right side shows an adaptive mapping scheme.
  • S is constructed by swapping bit b with bit b of S , swapping bit b with bit b of S , and exchanging the positions of four bits.
  • S is constructed by swapping the bits with bits of S and exchanging the positions of four bits. That is, also in the STBC, the signal constellation mapping on the data symbols to be transmitted can be changed to obtain diversity gain.
  • the left side shows a conventional mapping scheme and the right side shows an adaptive mapping scheme.
  • S is constructed by swapping and replacing bit b 2 with bit b 5 of S 2 , swapping and replacing bit b 3 with bit b 6 of S 2 , and exchanging the positions of four bits.
  • S is constructed by swapping and replacing the bits with the bits of S and exchanging the positions of four bits.
  • one data symbol is transmitted through one time slot, but plural data symbols may be transmitted through one time slot.
  • One data symbol is modulated into one transmission symbol when one data symbol is transmitted through one time slot.
  • plural data symbols are modulated into one transmission symbol and the transmission symbol can be said to include plural data symbols.
  • the data symbols can be spatially and temporally rearranged and the plural data symbols transmitted through one time slot can be rearranged.
  • the plural data symbols constituting one packet can be rearranged. Accordingly, the technical spirit of the invention includes cases where at least two data symbols different from each other are remapped by subcarriers, times, and spaces.
  • FIG. 8 is a block diagram illustrating a transmitter according to an embodiment of the invention.
  • plural data symbols may be transmitted through one time slot.
  • plural data symbols may be included in one packet.
  • the data symbols transmitted through one time slot can be remapped relative to each other.
  • the adaptive mapper can secure the additional diversity gain while obtaining the space and time diversity gains without any additional complexity.
  • the adaptive mapper can be embodied without modifying the structure of a general receiver such as an MMSE receiver or a ZF (Zero-Forcing) receiver.
  • a general receiver such as an MMSE receiver or a ZF (Zero-Forcing) receiver.
  • ZF Zero-Forcing
  • a transmitter 50 includes a channel encoder 51, an adaptive mapper 52, a spatial encoder 55, IFFT units 56-1, ..., 56-Nt, and delay units 57-1, ..., 57-(Nt-I).
  • the transmitter 50 uses the IFFT units 56-1, ..., 56-Nt as an OFDM modulator.
  • the transmitter 50 using the cyclic delay diversity transmits the data symbols through plural transmit antennas 59-1, ..., 59-Nt so as to have like or different power and different cyclic delays.
  • a signal transmitted through the plural transmit antennas is similar to a signal transmitted to a receiver through multiple paths, thereby greatly reducing the complexity in the receiver's detection of the signal.
  • the adaptive mapper 52 rearranges the data symbols temporally, spatially, and by subcarriers to obtain a diversity gain.
  • the rearranged data symbols are modulated into the transmission symbols and the transmission symbols are cyclically delayed, thereby obtaining the multiplexing diversity gain.
  • FIG. 10 is a diagram illustrating an example of an adaptive mapping.
  • the data symbols transmitted through the transmit antennas are S , S ( ⁇ ), S ( ⁇ ), and S ( ⁇ ).
  • the data symbol S is not delayed, but S ( ⁇ ) is cyclically delayed by ⁇ .
  • b (l) denotes the i-th bit of a symbol transmitted through the k-th transmit antenna.
  • the left side shows a data symbol C using a conventional mapping scheme and the right side shows a data symbol S using the adaptive mapping scheme.
  • C ' and S k ' denote data symbols which is transmitted through the i-th time slot in the k-th transmit antenna.
  • bits (b (1) , b (1) ) of the data symbol S are transmitted through the same path (the same transmit antenna) as bits (b (1) , b (1) ) equal thereto in position even by the use of the adaptive mapping, but bit b (1) is shifted to S ( ⁇ ), is cyclically
  • the number of bits swapped in each data symbol is exemplified as two per data symbol, but the number of bits to be swapped is not limited. One bit may be swapped or three or more bits may be swapped.
  • FIG. 11 is a diagram illustrating another example of the adaptive mapping.
  • the left side shows a conventional mapping scheme and the right side shows an adaptive mapping scheme.
  • bits spatially swapped with each other are subjected to replacement herein, but the bits not swapped may be subjected to replacement.
  • the swapping and replacement may be performed using two or more time slots.
  • FIG. 12 is a diagram illustrating an example of the adaptive mapping scheme in a system supporting multiple transmission rates.
  • bits (b , b ) of S are transmitted through the same paths (the same antennas) as bits (b , b ) of C at the same positions even by using the adaptive mapping scheme, but bit b of C is shifted to S ( ⁇ ), is cyclically delayed, and is transmitted throug ⁇ h a different transmit antenna.
  • bit b 2 of C 1 is shifted to S4
  • the data symbols are rearranged in S , S ( ⁇ ), S ( ⁇ ), and S ( ⁇ ) by the use of the adaptive mapping scheme and are transmitted through transmit antennas and/or cyclic delays different from each other.
  • the number of bits swapped in each data symbol is exemplified as two per data symbol, but the number of bits to be swapped is not limited. One bit may be swapped or three or more bits may be swapped.
  • the data symbols are spatially rearranged using one time slot, but the data symbols may be temporally and spatially rearranged using two or more time slots.
  • FIG. 13 is a diagram illustrating another example of the adaptive mapping.
  • the left side shows a conventional mapping scheme and the right side shows an adaptive mapping scheme.
  • By spatially swapping and replacing the bits at the level of bit it is possible to obtain an additional diversity gain.
  • the bits spatially swapped with each other are subjected to replacement herein, but the bits not swapped may be subjected to replacement.
  • the swapping and replacement may be performed using two or more time slots.
  • the swapping and replacement by bits are only an example. The rearrangement using the swapping and/or replacement by bits of the data symbols may be performed in various methods.
  • FIG. 14 is a block diagram illustrating a transmitter according to another embodiment of the invention. Here, the delay units of the transmitter 50 shown in FIG. 9 are moved to a frequency domain.
  • phase delay units 67-1, ..., 67-(Nt-I) are disposed between the spatial encoder 65 and the IFFT unit 68-1, ..., 68-Nt and serve to cyclically delay the phases of the symbols.
  • phase delay units 67-1, ..., 67-(Nt-I) in the frequency domain are equivalent to the delay unit 57-1, ..., 57-(Nt-I) in the time domain of the transmitter 50 shown in FIG. 9.
  • the time delay in the time domain and the phase delay in the frequency domain have duality with each other.
  • a receiver can swap the positions relative to the soft-decision bit output from a demapper by the use of the arrangement method at the time of transmission and can perform the final decoding. Since conventional receivers such as linear receivers can be used without any change, additional complexity is not required.
  • FIG. 15 is a block diagram illustrating a communication system according to an embodiment of the invention.
  • a communication system includes a transmitter 100 and a receiver 200.
  • the communication system can support an HARQ (Hybrid Automatic Repeat Request).
  • the transmitter 100 and the receiver 200 may be transceivers having both a transmitting function and a receiving function.
  • HARQ Hybrid Automatic Repeat Request
  • the transmitter 100 and the receiver 200 may be transceivers having both a transmitting function and a receiving function.
  • the transmitter 100 and the other transceiver receiving data and requesting for re-transmission is referred to as the receiver 200.
  • the transmitter 100 includes one channel encoder 110 and one adaptive mapper 120 and thus can process one codeword at a time, which is referred to as a single codeword (SCW) scheme.
  • SCW single codeword
  • the transmitter 100 includes a channel encoder 110, an adaptive mapper 120, a spatial encoder 130, a controller 150, and a receiving circuit 180.
  • the transmitter 100 further includes Nt (where Nt ⁇ l) transmit antennas 190-1, ..., 190-Nt.
  • the channel encoder 110 receives and encodes a series of information bits by the use of a predetermined coding method to form coded data.
  • the adaptive mapper 120 modulates the coded data by the use of a predetermined modulation scheme to provide data symbols.
  • the adaptive mapper 120 maps the coded data onto data symbols representing positions on a signal constellation.
  • the adaptive mapper 120 can adaptively map the coded data in response to a re-transmission request signal from the controller 150.
  • the modulation scheme performed by the adaptive mapper 120 is not limited, and may be an m-PSK (m-Phase Shift Keying) scheme or an m-QAM (m-Quadrature Amplitude Modulation) scheme.
  • the m-QAM may be one of 16-QAM, 64-QAM, and 256-QAM. An operation of the adaptive mapper 120 will be described later along with a data transmission method.
  • the spatial encoder 130 processes the data symbols output from the adaptive mapper 120 by the use of the MIMO pre-processing method.
  • the modulators 140-1, ..., 140-Nt modulate the symbols output from the spatial encoder 130 and transmits the modulated symbols through the transmit antennas 190-1, ..., 190-Nt.
  • a set of symbols output from the modulators 140-1, ..., 140-Nt and transmitted during a period (or in one time slot) is referred to as a transmission symbol.
  • the modulators 140-1, ..., 140-Nt can perform the IFFT (Inverse Fast Fourier Transform) process.
  • one data symbol is loaded in to one subcarrier and the transmission symbol transmitted by the plural carrier waves includes the plural data symbols.
  • the transmission symbol is an OFDM symbol.
  • the receiving circuit 180 receives the signals transmitted from the receiver 200 through the transmit antennas (190-1, ..., 190-Nt). The receiving circuit 180 digitalizes the received signals and sends the digitalized signals to the controller 150.
  • the controller 150 controls the entire operations of the transmitter 100.
  • the controller 150 extracts information from the signals received by the receiving circuit 180.
  • the operation of extracting the information includes usual demodulating and decoding operations.
  • the extracted information can include a re-transmission request signal.
  • the controller 150 controls the adaptive mapper 120 to prepare a retransmission symbol in response to the re-transmission request signal.
  • the information extracted from the signals received by the receiving circuit 180 includes CQU (Channel Quality Information).
  • the CQI may be information on a channel environment from the receiver 200 to the transmitter 100 or may be index information on the modulation and coding scheme.
  • the controller 150 controls the channel encoder 110 or the adaptive mapper 120 to adaptively change a coding scheme of the channel encoder 110 or a mapping scheme of the adaptive mapper 120.
  • the receiver 200 includes a spatial decoder 220, a demapper
  • the receiver 200 further includes Nr (where Nr ⁇ l) receiving antennas 290-1, ..., 290-Nr.
  • Nr (where Nr ⁇ l) receiving antennas 290-1, ..., 290-Nr.
  • the signals received by the receiving antennas 290-1, ..., 290-Nr are demodulated by the demodulators 210-1, ..., 210-Nr and are input to the spatial decoder 220.
  • the spatial decoder 220 processes the demodulated signals by the use of an MIMO postprocessing method in response to the MIMO control signal sent from the controller 270.
  • the MIMO control signal controls the decoding process on the basis of the space- time coding scheme of the receiver 100.
  • the MIMO control signal can be set in advance in a memory (not shown) of the controller 270. Alternatively, the MIMO control signal may be received from the transmitter 100.
  • the demapper 230 demaps the data symbols onto coded data in accordance with a demapping signal from the controller 270.
  • the demapping control signal used to control the demapper 230 on the basis of the mapping scheme of the adaptive mapper 120 of the transmitter 100.
  • the demapping control signal can be set in advance in the memory of the controller 270. Alternatively, the demapping control signal may be received from the transmitter 100.
  • the receiver 200 includes a combiner 240 that combines the re-transmitted symbols with the previous symbols. That is, in an HARQ system with a chase combining scheme or an incremental redundancy (IR) scheme, the combiner 240 combines the previous symbols with the re-transmitted symbols.
  • a combiner 240 As the combining method, an equal-gain combining method of weighting the previous data and the re-transmitted data in the same way and combining them by the use of their average values may be used. Alternatively, a maximal ratio combining (MRC) method of weighting the data in the different ways may be used.
  • the combining method is not limited and a variety of methods may be used.
  • this general inventive concept is not limited to the chase combining scheme or the IR scheme, but may be applied to the HARQ system for performing the channel decoding process by the use of only the re-transmitted symbols without being combined with the previous symbols.
  • the combiner 240 may be omitted from the receiver 200, as indicated by a dotted line in the figure.
  • the channel decoder 250 decodes the coded data by the use of the predetermined decoding method.
  • the error detector 260 detects whether any error exists in the decoded data bits by the use of a cyclic redundancy checking (CRC) process.
  • CRC cyclic redundancy checking
  • the controller 270 controls the entire operations of the receiver 200 and sends the re-transmission request signal to the transmitting circuit 280. Accordingly, the controller 270 can perform a general channel encoding process, a modulation process, and the like.
  • the controller 270 receives the detection result from the error detector 260 and determines whether the re-transmission of the symbols should be requested for.
  • the controller 270 generates a positive acknowledgement (ACK) signal when no error is detected, and generates a negative acknowledgement (NACK) signal when an error is detected.
  • ACK positive acknowledgement
  • NACK negative acknowledgement
  • the NACK signal may serve as a re-transmission request signal.
  • the controller 270 measures the channel quality from the received signals and sends a CQI signal.
  • a feedback signal such as a signal-to-noise ratio (SNR) or a bit error rate associated with the channel quality is fed back to the transmitter 100.
  • the transmission symbol transmitted from the transmitter 100 may further include a pilot symbol.
  • the transmitting circuit 280 receives the re-transmission request signal from the controller 270 and transmits the retransmission request signal through the receiving antennas 290-1, ..., 290-Nr.
  • FIG. 16 is a flowchart illustrating a data transmission method using the communication system shown in FIG. 15.
  • i and q denote a bit of the data symbol but do not define the order or details.
  • the data symbol may include a bit sequence representing complex values on a signal constellation and the number of bits representing the data symbol may be 4 or more bits, or 4 or less bits.
  • the data symbol is modulated into a transmission symbol by the modulators 140-1, ..., 140-Nt and the transmission symbol is transmitted. In order to clarify the description, one transmission symbol is assumed to be obtained from one data symbol, but the transmission symbol may include a group of data symbols.
  • the transmitter 100 transmits the data symbols S , S , S , and S
  • the data symbol S is transmitted through the first antenna 190-1, the data symbol S is transmitted through the second antenna 190-2, the data symbol S is transmitted through the third antenna 190-3, and the data symbol S is transmitted through the fourth antenna 190-4.
  • the receiver 200 performs a channel decoding process on the received data symbols
  • the receiver 200 checks an error (S 120).
  • the receiver 200 transmits an ACK signal to the transmitter 100 and waits for the transmission of a next symbol.
  • the receiver 200 detects an error and transmits a NACK signal as the re-transmission request signal (S 130).
  • the transmitter 100 transmits the re-transmission symbols S , S , S ,and S (S 140).
  • the re-transmission symbol S is transmitted through the first antenna 190-1
  • the re-transmission symbol S is transmitted through the second antenna 190-2
  • the re-transmission symbol S is transmitted through the third antenna 190-3
  • the re-transmission symbol S is transmitted through the fourth antenna 190-4.
  • the controller 150 spatially remaps the data symbols S , S , S , and S by the use of the adaptive mapper 120 to construct the re-transmission symbols S 1 , S 9 , S ⁇ ,and S 4 .
  • the spatial remapping [194] Referring to FIG. 17, the re-transmission symbol is formed by performing a bit remapping process on a signal constellation to the data symbols. At the first retransmission T2, the re-transmission symbols S and S are constructed by swapping
  • the re-transmission symbols S and S are constructed by swapping the bits (q , q ) of S with the bits (q , q ) of S and rearranging the bits in the symbols. That is, the re- S , and S are constructed by spatially swapping the bits of the data symbols S , S , S , and S with each other and rearranging the bits in the
  • the re-transmission symbols S and S are constructed by swapping the bits (q , q ) of S with the bits (q , q ) of S and rearranging the bits in the symbols.
  • the re-transmission symbols S and S are
  • the re-transmission symbols S , S , S , and S are constructed by spatially swapping the bits of the data symbols S , S , S , and S with each other and rearranging the bits in the symbols.
  • the number of bits to be spatially swapped is exemplified as two, but the number of bits to be swapped is not limited. One bit may be swapped or three or more bits may be swapped.
  • the bits of the data symbols are spatially swapped with each other at the first retransmission T2, and the bits of the data symbols are newly spatially swapped with each other and retransmitted at the second re-transmission T3. It is possible to obtain an additional diversity gain by the swapping of the bits of the data symbols.
  • FIG. 18 is a diagram illustrating an arrangement of re-transmission symbols according to another embodiment of the invention.
  • the re-transmission symbols S , S , S , and S are constructed by spatially swapping the bits of the data symbols S , S , S , and S with each other and rearranging the bits in the symbols, at the first re-transmission T2.
  • the bits in the data symbols S , S , S , and S can be swapped with each other. That is, the re-transmission symbols S , S , S , and S
  • 2 1 2 3 4 are constructed by swapping the bits of the data symbols S , S , S , and S with each other and replacing the LSB (Least Significant Bit) and the MSB (Most Significant Bit) with their complements.
  • the replacement is not limited to the LSB and the MSB, but the replacement with complements may be performed independent of the LSB and the MSB.
  • the intermediate bits may be replaced with the complements. and (i , i ) of the re-transmission symbol S are crossed each other.
  • the bits (q , q ) and (i , i ) of the re-transmission symbol S are crossed each other.
  • the retransmission symbols S and S are constructed by swapping the bits (i , i ) of S with the bits (i , i ) of S .
  • bit rearrangement of the data symbols may be performed in various methods.
  • the re-transmission symbols can be constructed by remapping the data symbols spatially, temporally, or by subcarriers.
  • the re-transmission symbols may be remapped every re-transmission. Alternatively, the remapping may be performed for only one retransmission. A different remapping method or the same remapping method may be used for each remapping.
  • the criterion for determining the remapping method is not limited.
  • the controller 150 may determined the remapping method in an open loop scheme, properly depending on the situations.
  • the maximum Doppler frequency, the delay spread, and the like can be considered as variables for determining the remapping method.
  • the controller 150 may receive the CQI signal and may determine the remapping method, depending on the channel quality fed back in the closed loop scheme.
  • the re-transmission symbols are constructed by remapping the data symbols, such a case is called a hybrid automatic repeat request (HARQ) system of Type I or a chase combining scheme in which the entire symbols are re-transmitted.
  • HARQ hybrid automatic repeat request
  • the technical spirit of the invention can be applied to the HARQ system of the IR scheme. That is, in the IR scheme, the entire symbols are not re-transmitted, but only redundant symbols are re-transmitted. In this case, by spatially remapping and then transmitting the redundant symbols, it is possible to secure the additional re-transmission gain.
  • the data symbol S is transmitted through the first antenna 190-1 and the data symbol S is transmitted through the second antenna 190-2.
  • the re-transmission symbol -S ' is transmitted through the first antenna 190-1 and the re-transmission symbol S ' is transmitted through the second antenna 190-2.
  • FIG. 23 is a graph illustrating a simulation result by SNR VS. BER (Bit Error Rate) and FIG. 24 is a graph illustrating a simulation result by SNR VS. FER (Frame Error Rate).
  • the chase combining scheme is used as the retransmission scheme in the 3GPP downlink and 16-QAM scheme and a 1/2 turbo code system are used. It is assumed that the number of antennas is 2 and a user speed is 100 km/h.
  • FIG. 25 is a graph illustrating a simulation result by SNR VS.
  • BER and FIG. 26 is a graph illustrating a simulation result by SNR VS. FER.
  • the user speeds are 30 km/h and 150 km/h, unlike FIGs. 23 and 24.
  • FIG. 27 is a block diagram illustrating a transmitter according to an embodiment of the invention.
  • an HARQ system using a cyclic delay diversity technique can be used.
  • a transmitter 300 includes a channel encoder 310, an adaptive mapper 320, a spatial encoder 330, a controller 350, and a receiving circuit 380.
  • the transmitter 300 further includes IFFT units 340-1, ..., 340-Nt as the OFDM modulators.
  • Information bits become data symbols while passing through the channel encoder 310 and the adaptive mapper 320.
  • the data symbols pass through the spatial encoder 330 and are converted into transmission symbols by the IFFT process of the IFFT units 340-1, ..., 340-Nt.
  • a CP Cyclic Prefix
  • the delay units 370-1, ..., 370-(Nt-I) are disposed between the IFFT units 340-1, ..., 340-Nt and the CP insertion units 345-1, ..., 345-Nt, and cyclically delay the transmission symbols.
  • the transmitter 300 is different from the transmitter 100 shown in FIG. 15, in that the delay units 370-1, ..., 370-(Nt-I) are added between the modulators 340-1, ..., 340-Nt and the transmit antennas 390-1, ..., 390-Nt.
  • the other operation is equal to those of the example shown in FIG. 15.
  • the delay units 370-1, ..., 370-(Nt-I) cyclically delay the transmission symbols transmitted through the transmit antennas 390-1, ..., 390-Nt.
  • the delay times Dl, ..., DNt-I delayed by the delay units 370-1, ..., 370-(Nt-I) may be different depending on the users and can be adjusted by receiving the corresponding information from the receiver in a feedback manner.
  • FIG. 28 is a diagram illustrating the re-transmission symbols used in the transmitter of FIG. 27.
  • a data symbol S is modulated into the transmission symbol and the transmission symbol is cyclically delayed and repeatedly transmitted through all the transmit antennas 390-1, ..., 390-Nt.
  • a retransmission symbol S is constructed by remapping the data symbol S by the use of the adaptive mapper 320 at the first re-transmission T2.
  • the re-transmission symbol S is modulated to a transmission symbol and the transmission symbol is cyclically delayed and transmitted through the transmit antennas 390-1, ..., 390-Nt.
  • the re-transmission symbol S remapped by the adaptive mapper 320 is cyclically delayed and transmitted through all the transmit antennas 390-1, ..., 390-Nt at the second re-transmission T3.
  • the delay units 370-1, ..., 370-(Nt-I) and the CP insertion units are identical to each other.
  • 345-1, ..., 345-Nt are replaced in position with each other. That is, the CP can be inserted after the symbols are delayed, or the symbols may be delayed after the CP is inserted.
  • FIG. 29 is a block diagram illustrating a transmitter according to another embodiment of the invention.
  • the delay units of the transmitter 300 of FIG. 27 are shifted to the frequency domain.
  • phase delay units 470-1, ..., 470-(Nt-I) are disposed between the spatial encoder 430 and the IFFT units 440-1, ..., 440-Nt and serve to cyclically delay the phases of the symbols.
  • the phase delay units 470-1, ..., 470-(Nt-I) in the frequency domain are equivalent to the delay unit 370-1, ..., 370-(Nt-I) in the time domain of the transmitter 300 shown in FIG. 27.
  • the time delay in the time domain and the phase delay in the frequency domain have duality with each other.
  • FIG. 30 is a diagram illustrating a transmitter and re-transmission symbols according to an embodiment of the invention.
  • a transmitter 500 includes a channel encoder 510, an adaptive mapper 520, a modulator 530, a controller 550, and a receiving circuit 560.
  • the transmitter 500 includes one antenna 590.
  • the data symbols output from the adaptive mapper 520 are modulated into transmission symbols by the modulator 530. Accordingly, the transmission symbols can include plural data symbols. In this case, one transmission symbol constitutes one packet. Here, three data symbols S , S , and S are included in one transmission symbol. However, this is only an example, and plural data symbols may be included in one transmission symbol, depending on the number of subcarriers.
  • the operation of the transmitter 500 is as follows. First, three data symbols S , S , and S are transmitted at the first transmission Tl. When an error is detected from the transmitted symbols and the NACK signal is transmitted, the re-transmission symbols S , S , and S remapped by the adaptive mapper 520 are transmitted at the first retransmission T2. The re-transmission symbols can be constructed by remapping the three data symbols. When an error is detected from the re-transmission symbols and the NACK signal is transmitted, the re-transmission symbols S , S , and S 3 remapped by the adaptive mapper 520 are transmitted at the second re-transmission T3. The new re-transmission symbols can be constructed by remapping the three data symbols.
  • the diversity is embodied by remapping the data symbols.
  • the remapping process includes the rearrangement of the bits of two or more data symbols different from each other. This process includes the rearrangement of the data symbols transmitted through one time slot, as well as temporally and spatially.
  • FIG. 31 is a block diagram illustrating a communication system according to an embodiment of the invention.
  • a communication system includes a transmitter 600 and a receiver 700.
  • the transmitter 600 N (where N>1) channel encoders 610-1, ..., 610-N, N adaptive mappers 620-1, ..., 620-N, a spatial encoder 630, a controller 650, and a receiving circuit 680.
  • the transmitter 650 includes Nt (where Nt ⁇ l) transmit antennas 190-1, ..., 190-Nt.
  • a technique of processing various codewords different in coding rate and coding scheme from each other by the use of the plural channel encoders 610-1, ..., 610-N and the adaptive mappers 620-1, ..., 620-N is called a multi codeword (MCW) technique.
  • MCW multi codeword
  • the channel encoders 610-1, ..., 610-N receive N information bits different from each other in parallel and encode the information bits in accordance with a predetermined coding method to form coded data.
  • the coded data are the codewords.
  • the coding methods applied to the information bits are independent of each other and different coding methods can be applied thereto.
  • the adaptive mappers 620-1, ..., 620-N modulate the coded data of the information bit streams by the use of the predetermined modulation scheme to provide data symbols.
  • the coded data are mapped to the symbols representing amplitudes and positions in a phase constellation by the adaptive mappers 620-1, ..., 620-N.
  • the adaptive mappers 620-1, ..., 620-N can adaptively modulate the coded data in response to the re-transmission request signal from the controller 650.
  • the spatial encoder 630 process the plural data symbols by the use of the space- time coding scheme so as to transmit the data symbols through plural transmit antennas 690-1, ..., 690-N.
  • the modulators 640-1, ..., 640-N modulate the symbols output from the spatial encoder 130 by the use of the multiple access modulation scheme and transmit the modulated symbols through the transmit antennas 690-1, ..., 690-N.
  • the receiving circuit 680 receives the signals from the receiver 700 through the transmit antennas 690-1, ..., 690-N.
  • the controller 650 controls the whole operation of the transmitter 600.
  • the controller 650 sends the re-transmission request signal transmitted from the receiving circuit 680 to the adaptive mappers 620-1, ..., 620-N so as to prepare the retransmission symbols.
  • the information extracted from the signals received from the receiving circuit 680 includes the CQI.
  • the controller 650 can adaptively change the coding method of the channel encoders 610-1, ..., 610-N and the mapping method of the adaptive mappers 620-1, ..., 620-N by the use of the CQI.
  • the receiver 700 includes a spatial decoder 720, demappers
  • the receiver 200 includes Mt (where Mt ⁇ l) antennas 790-1, ..., 790-Mt.
  • the signals received through the antennas 790-1, ..., 790-Mt are demodulated by the demodulators 710-1, ..., 710-M and are input to the spatial decoder 720.
  • the spatial decoder 720 reconstructs the transmission symbols in accordance with a decoding control signal from the controller 770.
  • the demappers 730-1, ..., 730-M demap the modulated symbols onto the coded data in accordance with a demapping control signal from the controller 70.
  • the receiver 700 further includes combiners 740-1, ..., 740-M that combine the re-transmitted symbols with the previous symbols. As indicated by the dotted line, the combiners 740-1, ..., 740-M may be omitted from the receiver 200 that performs the channel decoding process by the use of only the retransmitted symbols without combination with the previous symbols.
  • the channel decoders 750-1, ..., 750-M decode the coded data by the use of the predetermined decoding method.
  • the error detectors 760-1, ..., 760-M detect whether an error exists in the decoded data bits by the CRC check.
  • the controller 770 controls the whole operation of the receiver 700 and sends the re-transmission request signal and the like to the transmitting circuit 780.
  • the controller 770 receives the error detection result from the error detectors 760-1, 760-M and determines whether the retransmission should be requested for. When an error is not detected, the controller 770 generates the ACK signal and when an error is detected, the controller 770 generates the NACK signal.
  • the ACK signal or the NACK signal serves as the re-transmission request signal.
  • the transmitting circuit 780 receives the re-transmission request signal from the controller 770 and transmits the antennas 790-1, ..., 790-M.
  • the receiver 700 transmits the ACK signal to the transmitter 600 and waits for the transmission of next transmission symbols. However, it is assumed here that the receiver 700 detects an error and transmits the NACK signal as the re-transmission request signal (S630).
  • the receiver 700 performs the space-time decoding process on the received retransmission symbols S and S (, S , S ) and performs the channel decoding process thereon to check an error (S650). When no error is detected, the receiver 700 transmits the ACK signal to the transmitter 600 and waits for the transmission of next transmission symbols. However, it is assumed here that the receiver 700 detects an error and transmits the NACK signal as the re-transmission request signal (S660).
  • the adaptive mappers 620-1, ..., 620-N constructs the re-transmission symbols S and S (, S , S ) by spatially remapping the data symbols S and S (, S , S ).
  • the receiver 700 performs the space-time decoding process on the received retransmission symbols S and S and performs the channel decoding process thereon to check an error (S680).
  • the receiver 700 transmits the ACK signal or the NACK signal to the transmitter
  • the re-transmission symbols S and S are constructed by spatially swapping the bit data of the data symbols S and S , rearranging the bit data, and then replacing the LSB and the MSB with their complements.
  • the re-transmission symbols S , S , S and S are constructed by spatially swapping the bit data of the data symbols S , S , S and S with each other, rearranging the bit data, and then replacing the LSB and the MSB with their complements.
  • the re-transmission symbols S , S , S and S are constructed by spatially swapping the bit data of the data symbols S , S , S and S with each other, rearranging the bit data, and then replacing the intermediate bit data with their complements. That is, the
  • FIG. 39 is a diagram illustrating an arrangement of the re-transmission symbols for two transmit antennas and
  • FIG. 40 is a diagram illustrating an arrangement of the retransmission symbols for four transmit antennas.
  • the re-transmission symbols S , S , S and S are constructed by spatially swapping the bit data of the data symbols S , S , S and S with each other, rearranging the positions of the bit data, and then replacing the LSB and the MSB with their complements.
  • the bit data of the data symbols are swapped with each other. That is, the re-transmission symbols S , S , S and S are constructed by spatially swapping the bit data of the data symbols S , S , S and S , and rearranging the positions of the bit data in the symbols.
  • the re-transmission symbols S and S are constructed by swapping the bit data (a , a ) of S and the bit data (b , b ) of S with each other so that the bits are arranged to cross each other.
  • the re-transmission symbols S and S are constructed by swapping the bit data (c ) of S and the bit data (d 3 ) of S 4 with each other so that the bit data of S 3 are arrang °ed to cross each other.
  • the transmitter 800 includes Nt (where Nt>l) antennas 890-1, ..., 890-Nt and modulators 840-1, ..., 840-Nt.
  • Nt where Nt>l
  • the embodiment of FIG. 46 is different from the embodiment of FIG. 31, in that delay units 870-1, ..., 870-(Nt-I) are additionally disposed between the modulators 840-1, ..., 840-Nt and the antennas 890-1, ..., 890-Nt.
  • the other operations are similar to those of the embodiment of FIG. 31.
  • the delay units 870-1, ..., 870-(Nt-I) serve to cyclically delay the data symbols to be transmitted through the antennas 890-1, ..., 890-Nt.
  • the times (?1, ..., ?N-1) delayed by the delay units 870-1, ..., 870-(Nt-I) may have different values depending on the users and can be adjusted by the corresponding information fed back from the receiver.
  • the modulator of FIG. 46 is embodied in the OFDM scheme.
  • the symbols output from a spatial encoder 911 is converted into time domain samples by IFFT units 912-1, ..., 912-Nt.
  • a CP is inserted into the samples by CP insertion units 916-1, ..., 916-Nt and the samples are transmitted through the antennas 919-1, ..., 919-Nt.
  • Delays units 915-1, ..., 915-(Nt-I) are disposed between the IFFT units 912-1, ..., 912-Nt and the CP insertion units 916-1, ..., 916-Nt and serve to cyclically delay the samples.
  • the delay units of FIG. 46 are shifted to the frequency domain.
  • phase delay units 922-1, ..., 922-(Nt-I) are disposed between a spatial encoder 921 and IFFT units 923-1, ..., 923-Nt and serve to cyclically delay the phases of the symbols.
  • the time delay in the time domain and the phase delay in the frequency domain have duality.
  • FIG. 50 is a block diagram illustrating a transmitter according to an embodiment of the invention.
  • FIG. 51 is a diagram illustrating the re-transmission symbols.
  • the transmitter 930 includes one antenna 939.
  • 932-1, ..., 932-N outputs the plural data symbols in response to the multiple codewords output from the channel encoders 932-1, ..., 932-N.
  • the data symbols are converted into serial signals by the parallel-serial converter 933.
  • the swapping, replacement, crossing, change in modulation scheme, and delay for the re-transmission symbols can be considered when an error is detected from all the initially transmitted symbols and when an error is detected from a part of the initially transmitted symbols.
  • the bit rearrangement is performed on the symbols to be re-transmitted.
  • the bit rearrangement is performed on the symbols to be re-transmitted and the new symbols to be transmitted through antennas without an error.
  • the criterion for determining the remapping method is not limited.
  • the remapping method can be determined properly depending on the situations in the open- loop system.
  • the maximum Doppler frequency, the delay spread, and the like can be considered as the variable for determining the remapping method.
  • the remapping method can be determined depending on the channel quality fed back in the closed-loop system along with the CQI signal.
  • FIG. 52 is a flowchart illustrating a process of performing the HARQ of the chase combining scheme in the multiple codeword multiple antenna system.
  • the same symbols as the corresponding symbol is re-transmitted.
  • the symbol is adaptively mapped and re-transmitted so that the data bits of the corresponding symbol are swapped, replaced, and crossed with the data bits of the other symbols.
  • the receiver calculates the LLR values of the coded bits by the use of the demapping method which is used for the re-transmission and which is determined in advance in cooperation with the transmitter, and combines the calculated LLR values with the LLR values of the coded bits received previously, thereby enhancing the transmission reliability of data.
  • FIG. 53 is a flowchart illustrating a procedure of performing the HARQ of the IR scheme in the multiple codeword multiple antenna system.
  • the partial IR scheme of transmitting systematic bits and punctured parity bits at the time of re-transmission may be used.
  • the full IR scheme of additionally transmitting the parity bits at the time of re-transmission may be used.
  • the transmission symbols are not re-transmitted but redundant symbols are re-transmitted. It is possible to secure the addition re-transmission gain by spatially remapping and transmitting the redundant symbols.
  • FIG. 54 is a conceptual diagram illustrating an HARQ using multiple antennas in a multiple user environment.
  • the receiver detects an error from the received transmission block S (S720). When an error is not detected, the receiver transmits the ACK signal and waits for the transmission of a next transmission block. However, it is assumed here that the receiver detects an error and transmits the NACK signal as the re-transmission request signal (S730).
  • the transmitter transmits the re-transmission block S (740).
  • the adaptive mapper remaps the transmission block S by bits and/or spatially to construct the re-transmission block S .
  • the remapping method used for the re-transmission is various, which will be described later.
  • the receiver detects an error from the received re-transmission block Sl (S750).
  • the receiver 200 When not detecting an error, the receiver 200 transmits the ACK signal to the transmitter and waits for the transmission of a next symbol. However, it is assumed here that the receiver detects an error and transmits the NACK signal as the retransmission request signal (S760).
  • the transmitter When receiving the NACK signal, the transmitter transmits the remapped retransmission block S (S770).
  • the adaptive mapper remaps the transmission block S by bits and/or spatially to construct the re-transmission block S .
  • the receiver detects an error from the received re-transmission block S (S780).
  • the receiver 200 transmits the ACK signal or the NACK signal to the transmitter in accordance with the error detection result (S790).
  • the ACK signal is transmitted, the re-transmission of the corresponding transmission block is ended.
  • the request for re-transmission using the NACK signal can be repeated up to the n-th (where n ⁇ l) times which is a predetermined number of times.
  • the re-transmission process can be reset and the transmission of a next transmission block can be started. Alternatively, the current transmission block can be transmitted again.
  • FIG. 56 is a diagram illustrating transmission blocks corresponding to multiple antennas.
  • Tl denotes the second transmission, that is, the first re-transmission
  • Tn denotes the (n+l)-th transmission, that is, the n-th re-transmission.
  • the transmission block S is a transmission block at the first transmission
  • S is a transmission block at the first retransmission
  • S" is a transmission block at the n-th re-transmission.
  • a priori probability of the transmission signal c is A(c) and the transmission information is .
  • d is the MSB and d is the LSB.
  • the position of the MSB or the LSB can be
  • d may be the LSB and d may be the MSB.
  • Math Figure 4 the MSB, it is possible to reduce the difference in absolute LLR value between the symbols by performing the transmission using one inversion of the first transmission.
  • the bits relevant to the I axis are described, but the above-mentioned technique can be applied to the bits relevant to the Q axis in the same way.
  • the optimal BSI In the optimal BSI, the absolute value of the combined LLR received at the retransmission is constant at all the bit positions and in all the symbols.
  • the optimal BSI can be obtained by using four BSI schemes in total of two types of bit swapping and two types of bit inversion. That is, as for the transmission block transmitted first, the transmission block having been subjected to the bit swapping is transmitted at the first re-transmission, the transmission block having been subjected to the bit inversion on the LSB is transmitted at the second re-transmission, and the transmission block having been subjected to the bit swapping and the bit inversion is transmitted at the third re-transmission. This can be expressed as shown
  • Table 3 shows a variation of the combined LLR values when the re-transmission is performed using the BSI set. [368] Table 3
  • the same absolute LLR value can be obtained from the all the bit positions and all the symbols by four times of transmission.
  • the magnitude of the optimal BSI set is 4 or more in the modulation schemes of 16-QAM or greater.
  • the difference in absolute LLR value between the bits is reduced by the bit swapping and the absolute value difference in received LLR value between the symbols is reduced by the bit inversion. Since no greatest common divisor of the absolute values of the received LLR values exist in any M-QAM scheme, bits should be transmitted through all the bit positions at the re-transmission and should be transmitted by proper inversion so as to reduce the difference between the symbols.
  • (Nb/2) bit swapping operations should be performed in total.
  • the bit inversion process for reducing the absolute value difference of the received LLR between the symbols is determined on the basis of what kinds of absolute values of the received LLR values the bit positions have. Particularly, in an expression using the binary system, the necessary number of inversion operations is determined depending on the bit position having the greatest number of kinds among the bit positions. The bit located at the MSB position always has the most kinds of absolute values of the received LLR values.
  • Equation 6 N for obtaining the optimal BSI in an arbitrary modulation method M-QAM can be opt expressed by Equation 6.
  • FIG. 58 is a diagram illustrating a BSI set depending on the M-QAM scheme.
  • the cyclic shift means a scheme of shifting the bits one by one and the remaining bit is disposed again at the first position.
  • the cyclic shift is proposed because an arbitrary transmission bit should be transmitted through all the transmission bit positions.
  • the invention is not limited to the cyclic shift, but may employ various methods. However, the arbitrary transmission bit should not be re-transmitted through the once transmitted position.
  • the respective transmission blocks have two I-axis symbols and two Q-axis symbols.
  • the first transmission block S and the first re-transmission block S have a time difference of several ms. Accordingly, when the speed is great, the transmission blocks may experience channel responses independent of each other.
  • Equation 7 each of the four symbols can experience two channel conditions.
  • the number of channel conditions experienced by the symbols is defined as a diversity order (DO).
  • the transmission block S expressed by Equation 9 one bit in the I axis and one bit in the Q axis are swapped.
  • the DO is 3 in maximum in consideration of one re-transmission.
  • the transmission block S expressed by Equation 10 only two bits in the Q axis are swapped.
  • the DO is 2.
  • the transmission block S expressed by Equation 11 only one bit in the Q axis is swapped.
  • this method since two Q symbols experience three channel conditions and two Q symbols experience two channel conditions by means of the time diversity, DO is 2.5.
  • this method is lower in performance than the method expressed by Equation 8 in which three bits are swapped.
  • FIG. 59 illustrates a simulation result in which the BSA schemes are compared with each other at a user equipment speed of 120 km/h.
  • FIG. 60 illustrates a simulation result in which the BSA schemes are compared with each other at a user equipment speed of 30 km/h.
  • the schemes expressed by Equations 7 to 10 are compared in the simulations and the link performance is expressed by FER (Frame Error Rate) Vs. SNR. It is checked what influence the BSA scheme has on the link performance, by considering only the bit swapping between the antennas without considering the BSI scheme.
  • FIG. 61 is a diagram illustrating an example of the BSA scheme with an arbitrary number of antennas.
  • FIG. 62 is a diagram illustrating another example of the BSA scheme with an arbitrary number of antennas and an M-QAM modulation scheme.
  • the respective columns can be transmitted with different degrees of shift.
  • the maximum diversity can be expected by performing a multi-step cyclic shift process.
  • the bits of the I symbol and the Q symbol are cyclically shifted with different degrees of shift depending on the positions of the bits. For example, the degree of shift of the second bit of the I symbol may be set to 1 and the degree of shift of the third bit of the I symbol may be set to 2.
  • the bits of one symbol can be transmitted through different antennas. Accordingly, when the number of bits (Nb/2) of the I symbol or the Q symbol is greater than the number of transmit antennas Nt, it is possible to obtain additional diversity of (Nb/2) in maximum.
  • the degree of shift may be transmitted through the downlink or may be a value determined in advance by the transmitter and the receiver.
  • the re-transmission is performed two or more times. Since a relatively large time difference can exist between the re-transmissions, the channel responses between the re-transmissions are independent of each other. At this time, the previous BSA scheme does not affect the determination of the BSA scheme every retransmission. Accordingly, the BSA scheme shown in FIG. 62 can be used as the BSA scheme for the second or subsequent re-transmission without any change, regardless of the previous BSA scheme. However, when the speed of the user equipment decreases, the previous BSA and the current BSA may have some correlation. Accordingly, by changing the degree of shift of the respective columns in the multi-step cyclic shift structure depending on the number of re-transmissions, better performance can be expected.
  • FIG. 63 is a diagram illustrating a mapping method of a transmission block at the time of re-transmission in a system using the 16-QAM scheme and two transmit antennas.
  • the BSI and the BSA are independent of each other and do not affect each other. Accordingly, a combination of the respective optimum methods is the whole optimum method.
  • the BSI scheme of swapping the MSB and the LSB in the first transmission block S and the BSA scheme of swapping the bits in the I channel and the Q channel bit by bit are used for the first re-transmission block S .
  • the BSI scheme of swapping the MSB and the LSB in the first transmission block S and inverting the right bit positions in the I axis and the Q axis and the BSA scheme of swapping the bits in the I axis and the Q axis bit by bit are used for the third re-transmission block S . 7 U 7 1,2 7 1,3 7 1,4 #1,1 #1,2 #1,3 #1,4

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Abstract

Le procédé de transmission de données consiste à mettre en oeuvre un remappage binaire sur une constellation de signaux afin de former une pluralité de symboles de données, à moduler la pluralité de symboles de données et à transmettre les symboles de données modulés. Par remappage, il est possible d'obtenir un gain de diversité sans complexité supplémentaire.
EP07807979A 2006-08-07 2007-08-07 Procédé de transmission de données utilisant un mappage sur une constellation de signaux Ceased EP2057772A4 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
KR20060074375 2006-08-07
KR1020060106557A KR101287272B1 (ko) 2006-08-07 2006-10-31 적응적 맵퍼를 이용한 데이터 전송 방법 및 복합 자동재전송 방법
KR1020060107442A KR101253175B1 (ko) 2006-08-07 2006-11-01 적응적 맵퍼를 이용한 복합 자동 재전송 방법 및 이를이용한 송신기
KR1020060115820A KR101208543B1 (ko) 2006-08-07 2006-11-22 복수의 순환 지연 값에 따라 순환 지연을 수행하는 다중안테나 시스템에서의 송신 방법
KR1020070016649A KR101299911B1 (ko) 2006-08-07 2007-02-16 다이버시티 이득을 높이는 데이터 재전송 방법
PCT/KR2007/003798 WO2008018742A1 (fr) 2006-08-07 2007-08-07 Procédé de transmission de données utilisant un mappage sur une constellation de signaux

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EP2057772A1 true EP2057772A1 (fr) 2009-05-13
EP2057772A4 EP2057772A4 (fr) 2011-04-27

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EP07807979A Ceased EP2057772A4 (fr) 2006-08-07 2007-08-07 Procédé de transmission de données utilisant un mappage sur une constellation de signaux

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EP (1) EP2057772A4 (fr)
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JP5103358B2 (ja) * 2008-11-04 2012-12-19 株式会社エヌ・ティ・ティ・ドコモ 基地局装置、移動端末装置、移動通信システム及び情報再送方法
JP5461824B2 (ja) * 2008-11-04 2014-04-02 株式会社Ｎｔｔドコモ 基地局装置、移動端末装置、移動通信システム及び情報再送方法
WO2010071334A2 (fr) 2008-12-16 2010-06-24 Lg Electronics Inc. Procédé et appareil pour réaliser une harq dans un système de communication sans fil
KR101650623B1 (ko) * 2014-05-26 2016-08-24 한국과학기술원 가변적인 안테나 선택 및 공간 다중화를 수행하여 데이터를 전송하는 장치, 데이터를 전송하는 방법, 데이터를 수신하는 장치, 및 데이터를 수신하는 방법

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Also Published As

Publication number Publication date
KR20080013662A (ko) 2008-02-13
KR101299911B1 (ko) 2013-08-23
WO2008018742A1 (fr) 2008-02-14
KR20080013661A (ko) 2008-02-13
KR20080013682A (ko) 2008-02-13
EP2057772A4 (fr) 2011-04-27
KR101253175B1 (ko) 2013-04-10
KR101287272B1 (ko) 2013-07-17

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