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`
`
`Exhibit B
`
`
`
`
`
`

`

`Case 1:21-cv-00075-UNA Document 1-2 Filed 01/26/21 Page 2 of 16 PageID #: 33
`
`US007567622B2
`
`(12) United States Patent
`Wengerter et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7.567,622 B2
`*Jul. 28, 2009
`
`(54) CONSTELLATION REARRANGEMENT FOR
`ARQ TRANSMIT DIVERSITY SCHEMES
`
`6,476.734 B2 11/2002 Jeong et al.
`6,580,705 B1
`6/2003 Riazi et al.
`
`(75) Inventors: Christian Wengerter, Kleinheubach
`(DE); Alexander Golitschek Edler Von
`Elbwart, Darmstadt (DE); Eiko Seidel,
`Darmstadt (DE)
`(73) Assignee: Panasonic Corporation, Osaka (JP)
`(*) Notice:
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`This patent is Subject to a terminal dis-
`claimer
`
`(21) Appl. No.: 11/633,421
`(22) Filed:
`Dec. 5, 2006
`
`(65)
`
`Prior Publication Data
`US 2007/O147531A1
`Jun. 28, 2007
`
`Continued
`(Continued)
`FOREIGN PATENT DOCUMENTS
`
`CN
`
`1333605
`
`1, 2002
`
`(Continued)
`OTHER PUBLICATIONS
`Wengerter, Cet al., “Advanced Hybrid ARQ Technique Employing a
`Signal Constellation Rearrangement.” 2002 IEEE 56", IEEE Vehicu
`lar Technology Conference Proceedings, Vancouver, Canada, vol. 1
`of 4 conf. 56, XPO10608782, pp. 2002-2006. Sep. 24, 2002.
`(Continued)
`Primary Examiner Temesghen Ghebretinsae
`(74) Attorney, Agent, or Firm—Dickinson Wright, PLLC
`
`57
`(57)
`
`ABSTRACT
`
`An ARQ (re-) transmission method of transmitting data in a
`Related U.S. Application Data
`wireless communication system wherein data packets a
`(63) Continuation of application No. 10/501,906, filed as
`transmitted from a transmitter to a receiver, using a first
`application No. PCT/EPO2/11694 on Oct. 18, 2002
`transmission and a second transmission based on a repeat
`R Pat. No 7. 54,961
`•
`u. Yos
`s
`request. The method comprises the steps of modulating data
`•
`L vs -
`s r. a- is - - - -
`at the transmitter using a first signal constellation pattern to
`(51) Int. Cl
`obtain a first data symbol. The first data symbol is transmitted
`(2006.01)
`tion 7/02
`as the first transmission to the receiver using a first diversity
`(52) U.S. Cl. ....................... 375/267; 3.53,752S. branch. Further, the data is modulated at the transmitter using
`58) Field of Classification S
`h
`375,267
`a second signal constellation pattern to obtain a second data
`(58) Field o 3 lisag St. 08,261.370/349, 46 5.
`symbol. Then, the second data symbol is transmitted as the
`s
`s
`s
`s 7 14f748, 70 7 86
`second transmission to the receive over a second diversity
`1
`S
`lication file f
`hhi s
`s
`branch. Finally, the received first and second data symbol data
`ee application file for complete search history.
`symbol are diversity combined at the receiver. The invention
`References Cited
`further relates to a transmitter and a receiver embodied to
`carry out the method of the invention.
`
`(56)
`
`U.S. PATENT DOCUMENTS
`6,356,528 B1
`3/2002 Lundby et al.
`
`20 Claims, 6 Drawing Sheets
`
`----------
`11
`A
`SOURCE
`
`FEC
`ENCODER
`
`
`
`
`
`FC
`DEC05ER
`
`BER
`
`COMBINING -
`UNT
`
`MApplms
`UN
`
`RECEWING
`UN
`
`
`
`EMORARY
`BFFER
`
`-
`22
`
`COMMUNICATION SECTION
`
`AOC
`
`

`

`Case 1:21-cv-00075-UNA Document 1-2 Filed 01/26/21 Page 3 of 16 PageID #: 34
`
`US 7.567,622 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`6,769,085
`6,892,341
`7,154,961
`7,298.717
`2002fOO3698O
`2002/0114398
`2003/OO39229
`2003/0048857
`
`T/2004
`B2
`5/2005
`B2
`B2* 12/2006
`B2 * 1 1/2007
`A1
`3, 2002
`A1
`8, 2002
`A1* 2, 2003
`A1
`3, 2003
`
`Von Elbwart et al.
`Golitschek et al.
`Wengerter et al. .......... 375,267
`Hui et al. .................... 370,329
`Lundby et al.
`Lin et al.
`Ostman ...................... 370,335
`Onggosanusi et al.
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`EP
`
`O735701
`1172.959
`
`10, 1996
`1, 2002
`
`WO
`
`8, 2002
`O2O67491
`OTHER PUBLICATIONS
`“Enhanced HARQ Method with Signal Constellation Rearrange
`ment.” TSG-RAN Working Group 1 Meeting, No. 19, XP002229383,
`Feb. 24, 2001.
`Alk, C. et al., “Bit-Interleaved Coded Modulation with Signal Space
`Diversity in Rayleigh Fading.” Signals, Systems, and Computers,
`Conference Record of the Thirty-Third Asllomar Conference,
`Piscataway, NJ, IEEE, XP 010373787, pp. 1003-1007, Oct. 24, 1999.
`Le Goff, S. et al., “Turbo-Codes and High Spectral Efficiency Modu
`lation.” Telecom Bretagne, France Telecom University, IEEE, XP
`0.10608782, pp. 645-649, 1994.
`European Office Action dated Nov. 25, 2005.
`Chinese Office Action dated Mar. 3, 2006 with English translation.
`* cited by examiner
`
`

`

`Case 1:21-cv-00075-UNA Document 1-2 Filed 01/26/21 Page 4 of 16 PageID #: 35
`
`U.S. Patent
`
`Jul. 28, 2009
`
`Sheet 1 of 6
`
`US 7.567,622 B2
`
`i
`
`i2
`
`lm
`100
`OOO1 OOll
`1011
`o O O O
`1010 1000 0000 000
`
`
`
`1 1 0
`
`1 00 000 OO
`
`92
`
`11
`
`1 01
`
`O. O. O.
`
`Mapping 1 (bit-mapping order: iqliog2)
`
`F.G. 1
`
`

`

`Case 1:21-cv-00075-UNA Document 1-2 Filed 01/26/21 Page 5 of 16 PageID #: 36
`
`U.S. Patent
`
`Jul. 28, 2009
`
`Sheet 2 of 6
`
`US 7.567,622 B2
`
`il
`
`Im
`O010 1010 1000 OOOO
`
`1 00 000
`O110 1 1 0 1
`O O O O
`
`
`
`Re
`
`O O O O
`O)11
`1111
`101 001
`
`O O O O
`O011
`1 011
`1001 0001
`
`Mapping 2 (bit-mapping order: i.1qigo)
`
`FG. 2
`
`

`

`«JSmU
`
`a5,17mm
`
`32#.BD2
`
`am.mm,mm.wE<mor.
`
`Case 1:21-cv-00075-UNA Document 1-2 Filed 01/26/21 Page 6 of 16 PageID #: 37
`6
`e
`m
`7
`
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`ELEH:;mtIIIII
`.1DH.S9
`1.:mmoooooooowu.882822828:88SS2:
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`m688as2:8:s:as:5::Sm.MOOOOGOO0wmSmm88:S::S:SE38:8:22sooooccoomom.Smm
`
`
`
`
`
`m@323“EEOm:E%E-:£vgang/HENE:”EEOmagmafiammsammE
`
`
`

`

`Case 1:21-cv-00075-UNA Document 1-2 Filed 01/26/21 Page 7 of 16 PageID #: 38
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`U.S. Patent
`
`US 7.567,622 B2
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`\
`
`
`
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`
`
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`

`

`Case 1:21-cv-00075-UNA Document 1-2 Filed 01/26/21 Page 8 of 16 PageID #: 39
`
`U.S. Patent
`
`Jul. 28, 2009
`
`Sheet 5 of 6
`
`US 7.567,622 B2
`
`
`
`

`

`Case 1:21-cv-00075-UNA Document 1-2 Filed 01/26/21 Page 9 of 16 PageID #: 40
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`U.S. Patent
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`US 7.567,622 B2
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`
`
`
`
`
`
`

`

`Case 1:21-cv-00075-UNA Document 1-2 Filed 01/26/21 Page 10 of 16 PageID #: 41
`
`1.
`CONSTELLATION REARRANGEMENT FOR
`ARQ TRANSMIT DIVERSITY SCHEMES
`
`US 7,567,622 B2
`
`2
`bits have different reliabilities depending on the chosen map
`ping. This leads for most FEC (e.g. Turbo Codes) schemes to
`a degraded decoder performance compared to an input of
`more equally distributed bit reliabilities.
`In conventional communication systems the modulation
`dependent variations in bit reliabilities are not taken into
`account and, hence, usually the variations remain after com
`bining the diversity branches at the receiver.
`The object of the invention is to provide an ARQ (re-)
`transmission method, a transmitter and a receiver which show
`an improved performance with regard to transmission errors.
`This object is solved by a method, transmitter and receiver as
`set forth in the independent claims.
`The invention is based on the idea to improve the perfor
`mance at the receiver by applying different signal constella
`tion mappings to the available distinguishable transmit diver
`sity branches and ARQ (re-) transmissions. The invention is
`applicable to modulation formats, where more than 2 bits are
`mapped onto one modulation symbol, since this implies a
`variation in reliabilities for the bits mapped onto the signal
`constellation. The variations depend on the employed map
`ping and on the actually transmitted content of the bits.
`Depending on the employed modulation format and the
`actual number of bits mapped onto a single modulation sym
`bol, for a given arbitrary number (N> 1) of available diversity
`branches and required retransmissions the quality of the aver
`aging process is different. Averaging in the sense of the
`present invention is understood as a process of reducing the
`differences in mean combined bit reliabilities among the dif
`ferent bits of a data symbol. Although it might be that only
`after using several diversity branches or paths a perfect aver
`aging with no remaining differences is achieved, averaging
`means in the context of the document any process steps in the
`direction of reducing the mean combined bit reliability dif
`ferences. Assuming on average an equal SNR for all available
`diversity branches and ARQ transmissions, for 16-QAM 4
`mappings (4 diversity branches) would be needed to perfectly
`average out the reliabilities for all bits mapped on any symbol.
`However, not always the number of available transmit diver
`sity branches and/or the number of ARQ transmissions is
`Sufficient to perform a perfect averaging. Hence, the averag
`ing should then be performed on a best effort basis as shown
`in the example below.
`The present invention will be more readily understood
`from the following detailed description of preferred embodi
`ments with reference to the accompanying figures which
`show:
`FIG. 1 an example for a 16-QAM signal constellation;
`FIG. 2 an example for a different mapping of a 16-QAM
`signal constellation;
`FIG.3 two further examples of 16-QAM signal constella
`tions;
`FIG. 4 an exemplary embodiment of a communication
`system according to the present invention;
`FIG. 5 details of a table for storing a plurality of signal
`constellation patterns; and
`FIG. 6 shows the communication system according to the
`present invention with an interleaver/inverter section.
`The method described here performs a combined averag
`ing of bit reliabilities considering the transmit diversity
`branches. The following detailed description is shown for a
`square 16-QAM with Gray mapping. However, without loss
`of generality the shown example is extendable to other
`M-QAM and M-PSK (with log(M)>2) formats. Moreover,
`the examples are shown for transmit diversity and HARQ
`schemes transmitting an identical bit-sequence on both
`
`10
`
`15
`
`This is a continuation of application Ser. No. 10/501,906
`filed Dec. 6, 2004, now U.S. Pat. No. 7,154,961 the priority of 5
`which is claimed under 35 USC S 120. application Ser. No.
`10/501,906 is a 371 of PCT/EP2002/01 1694 filed Oct. 18,
`2002.
`The present invention relates generally to ARQ (re-) trans
`mission techniques in wireless communication systems and
`in particular to a method, transceiver and receiver using trans
`mit diversity Schemes wherein data packets are transmitted
`using a first and a second transmission based on a repeat
`request, and the bit-to-symbol mapping is performed differ
`ently for different transmitted diversity branches. The inven
`tion is particularly applicable to systems with unreliable and
`tirne-varying channel conditions resulting in an improved
`performance avoiding transmission errors.
`There exist several well known transmit diversity tech
`niques wherein one or several redundancy versions relating to
`identical data are transmitted on several (at least two) diver
`sity branches “by default' without explicitly requesting (by a
`feedback channel) further diversity branches (as done in an
`ARO scheme by requesting retransmissions). For example
`the following schemes are considered as transmit diversity:
`Site Diversity: The transmitted signal originates from dif
`ferent sites, e.g. different base stations in a cellular envi
`rOnment.
`Antenna Diversity: The transmitted signal originates from
`different antennas, e.g. different antennas of a multi
`antenna base station.
`Polarization Diversity: The transmitted signal is mapped
`onto different polarizations.
`Frequency Diversity: The transmitted signal is mapped e.g.
`on different carrier frequencies or on different frequency
`hopping sequences.
`Time Diversity: The transmitted signal is e.g. mapped on
`different interleaving sequences.
`Multicode Diversity: The transmitted signal is mapped on
`different codes in e.g. a CDMA (Code Division Multiple
`Access) system.
`There are known several diversity combining techniques.
`The following three techniques are the most common ones:
`Selection Combining: Selecting the diversity branch with
`the highest SNR for decoding, ignoring the remaining
`OS.
`Equal Gain Combining: Combining received diversity
`branches with ignoring the differences in received SNR.
`Maximal Ratio Combining: Combining received diversity
`branches taking the received SNR of each diversity
`branch into account. The combining can be performed at
`bit-level (e.g. LLR) or at modulation symbol level.
`Furthermore, a common technique for error detection/cor
`rection is based on Automatic Repeat request (ARQ)
`schemes together with Forward Error Correction (FEC),
`called hybrid ARQ (HARQ). If an error is detected within a
`packet by the Cyclic Redundancy Check (CRC), the receiver
`requests the transmitter to send additional information (re
`transmission) to improve the probability to correctly decode
`the erroneous packet.
`In WO-02/067491 A1 a method for hybrid ARQ transmis
`sions has been disclosed which averages the bit reliabilities
`over Successively requested retransmissions by means of sig
`nal constellation rearrangement.
`As shown therein, when employing higher order modula
`tion formats (e.g. M-PSK, M-QAM with log(M)>2), where
`more than 2 bits are mapped onto one modulation symbol, the
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`

`

`Case 1:21-cv-00075-UNA Document 1-2 Filed 01/26/21 Page 11 of 16 PageID #: 42
`
`US 7,567,622 B2
`
`3
`branches and all. HARQ transmissions (single redundancy
`version scheme). Then again, an extension to a transmit diver
`sity and HARQ scheme transmitting only partly identical bits
`on the diversity branches and HARQ transmissions can be
`accomplished. An example for a system using multiple redun
`dancy versions is described in copending EP 01127244, filed
`on Nov. 16, 2001. Assuming a Turbo encoder, the systematic
`bits can be averaged on a higher level as compared to the
`parity bits.
`Although the below examples give details of an embodi
`ment with the special case of hybrid ARQ (HARQ), it should
`be noted that the inclusion of an FEC code is not necessary for
`the present invention to show performance gains. However
`the highest performance gains can beachieved with the use of
`HARQ.
`The following example describes a method with two diver
`sity branches and HARQ.
`1 Transmission:
`Assuming a transmit diversity Scheme with two generated
`diversity branches, which are distinguishable at the receiver
`(e.g. by different spreading or scrambling codes in a CDMA
`system) and a transmission of the same redundancy version,
`25
`usually the received diversity branches are combined at the
`receiver before applying-the FEC decoder. A common com
`bining technique is the maximal ratio combining, which can
`be achieved by adding the calculated log-likelihood-ratios
`LLRs from each individual received diversity branch.
`The log-likelihood-ratio LLR as a soft-metric for the reli
`ability of a demodulated bit b from a received modulation
`symbol rX+y is defined as follows:
`
`10
`
`15
`
`30
`
`4
`the signal-to-noise ratio. Under the assumption of a uniform
`signal constellation (X3X) equations (2) and (3) can be
`fairly good approximated approximated, as shown in S. Le
`Goff, A. Glavieux, C. Berrou, “Turbo-Codes and High Spec
`tral Efficiency Modulation.” IEEE SUPERCOMM/ICC 94,
`Vol. 2, pp. 645-649, 1994, and Ch. Wengerter, A. Golitschek
`Edler von Elbwart, E. Seidel, G. Velev, M. P. Schmitt,
`“Advanced Hybrid ARQ Technique Employing a Signal Con
`stellation Rearrangement.” IEEE Proceedings of VTC 2002
`Fall, Vancouver, Canada, September 2002, by
`
`The mean LLR for i and is for a given transmitted modu
`lation symbol yields the values given in Table 1 (substituting
`4Kx by A). Mean in this sense, refers to that the mean
`received value for a given transmitted constellation point,
`exactly matches this transmitted constellation point. Indi
`vidual samples of course experience noise according to the
`parameter K. However, for a Gaussian channel the mean
`value of the noise process is Zero. In case of transmitted
`modulation symbols Oq1q and 1 q1q, where q and q are
`arbitrary, the magnitude of the mean LLR (i) is higher than of
`the mean LLR (i). This means that the LLR for the MSB i
`depends on the content of the LSB i. e.g. in FIG. 1 i has a
`higher mean reliability in case the logical value for is equals
`1 (leftmost and rightmost columns). Hence, assuming a uni
`form distribution of transmitted modulation symbols, on
`average 50% of the MSBs it have about three times the mag
`nitude in LLR of i.
`
`LLR(b) = in Prb = 1 2.
`
`35
`
`(1)
`
`TABLE 1
`
`Mean LLRs for bits mapped on the in-phase component
`of the signal constellation for Mapping 1 in FIG.
`1 according to equations (4) and (5).
`
`40
`
`As can be seen from FIG. 1 (bars indicate rows/columns for
`which the respective bit equals 1), the mappings of the in
`phase component bits and the quadrature component bits on
`the signal constellation are orthogonal (for M-PSK the LLR
`calculation cannot be simplified by separating into complex
`45
`components, however the general procedure of bit-reliability
`averaging is similar). Therefore, it is Sufficient to focus on the
`in-phase component bits i and i. The same conclusions
`apply then for q1 and q2.
`Assuming that Mapping 1 from FIG. 1 is applied for the
`bit-to-symbol mapping for the 1 diversity branch, the log
`likelihood-ratio LLR of the most significant bit (MSB) i? and
`the least significant bit (LSB) is yields the following equa
`tions for a Gaussian channel:
`
`50
`
`55
`
`(2)
`
`(3)
`
`where X denotes the in-phase component of the normalized
`received modulation symbol rand Kis a factor proportional to
`
`60
`
`65
`
`If now adding a 2" transmit diversity branch transmitting
`e.g. an identical bit sequence prior art schemes would employ
`an identical mapping to the 1 diversity branch. Here, it is
`proposed to-employ a 2" signal constellation mapping (Map
`ping 2) according to FIG. 2, which yields the mean LLRS
`given in Table 2.
`
`TABLE 2
`
`Mean LLRs for bits mapped on the in-phase component
`of the signal constellation for Mapping 2 in FIG. 2.
`
`Symbol
`(i191292)
`
`Oq10q2
`Oq192
`1910q2
`1911q2
`
`Mean value of x
`
`Mean LLR (i)
`
`Mean LLR (i)
`
`Xo
`X
`-Xo
`-X
`
`-A
`-A
`A
`A
`
`-3A
`3A
`-A
`A
`
`Comparing now the soft-combined LLRs of the received
`diversity branches applying the constellation rearrangement
`
`

`

`Case 1:21-cv-00075-UNA Document 1-2 Filed 01/26/21 Page 12 of 16 PageID #: 43
`
`US 7,567,622 B2
`
`6
`
`TABLE 3-continued
`
`5
`(Mapping 1+2) and applying the identical mappings (Map
`ping 1+1, prior art), it can be observed from Table 3 that the
`combined mean LLR values with applying the constellation
`rearrangement have a more uniform distribution (Magni 5
`tudes: 4x4A and 4x2A instead of 2x6A and 6x2A). For most
`FEC decoders (e.g. Turbo Codes and Convolutional Codes)
`this leads to a better decoding performance. Investigations
`have revealed that in particular Turbo encoding/decoding sys
`tems exhibit a superior performance. It should be noted, that 10
`the chosen mappings are non exhaustive and more combina
`tions of mappings fulfilling the same requirements can be
`found.
`
`TABLE 3
`
`Mean LLRs (per branch) and combined mean LLRs for bits
`mapped on the in-phase component of the signal constellation
`for the diversity branches when employing Mapping 1 and
`2 and when employing 2 times Mapping 1.
`
`15
`
`2O
`
`Constellation
`Rearrangement
`Mapping 1 + 2
`
`Prior Art
`No Rearrangement
`Mapping 1 + 1
`
`Symbol
`(iqiq2)
`Oq10q2
`Oq1192
`1910q2
`1911q2
`Oq10q2
`Oq1192
`1910q2
`1911q2
`Oq10q2
`Oq1192
`
`Mean
`LLR (ii)
`-A
`-3A
`A
`3A
`-A
`-A
`A
`A
`-2A
`-4A
`
`Mean
`Mean
`LLR (i2) LLR (ii)
`-A
`-A
`A
`-3A
`-A
`A
`A
`3A
`-3A
`-A
`3A
`-3A
`-A
`A
`A
`3A
`-4A
`-2A
`-4A
`-6A
`
`Mean
`LLR(i2) 25
`-A
`A
`-A
`A
`-A
`A
`-A
`A
`-2A
`2A
`
`30
`
`Transmit
`
`Diversity
`Branch
`1
`
`2
`
`Combined
`1 + 2
`
`Mean LLRs (per branch) and combined mean LLRs for bits
`mapped on the in-phase component of the signal constellation
`for the diversity branches when employing Mapping 1 and
`2 and when employing 2 times Mapping 1.
`
`Transmit
`
`Diversity
`Branch
`
`Constellation
`Rearrangement
`Mapping 1 + 2
`
`Prior Art
`No Rearrangement
`Mapping 1 + 1
`
`Symbol
`(i1911292)
`
`Mean
`Mean
`LLR (i) LLR (i2)
`
`Mean
`Mean
`LLR (i) LLR (i2)
`
`1910q2
`1911q2
`
`2A
`4A
`
`-2A
`2A
`
`2A
`6A
`
`-2A
`2A
`
`2" and Further Transmissions:
`In case the 1 transmission has not been successfully
`decoded the receiver requests a retransmission (2" transmis
`sion). Assuming for 2" transmission also 2 transmit diversity
`branches are available, the 2 additional mappings (mapping 3
`and mapping 4 in FIG.3) are employed to further improve the
`averaging of the bit reliabilities as shown in Table 4. In this
`example (assuming an equal SNR for all received signals) the
`averaging is performed perfectly after receiving 2 transmit
`diversity branches times 2 transmissions (possibility to
`employ 4 different mappings—sufficient for 16-QAM). Table
`4 compares the LLRs with and without applying the proposed
`Constellation Rearrangement. Having a closer look at the
`combined LLRs, it can be seen that with application of the
`Constellation Rearrangement the magnitude for all bit reli
`abilities results in 6A.
`It should be noted again, that the chosen mappings are non
`exhaustive and more combinations of mappings fulfilling the
`same requirements can be found.
`
`TABLE 4
`
`Mean LLRs (per branch) and combined mean LLRs for bits mapped on the in-phase component
`of the signal constellation for the diversity branches and (re-) transmissions
`when employing Mappings 1 to 4 and when employing 4 times Mapping 1.
`
`Transmit
`
`Diversity
`Branch
`
`1
`
`2
`
`3
`
`4
`
`Combined
`1 + 2 + 3 + 4
`
`Prior Art
`Constellation
`No Rearrangement
`Rearrangement
`Mapping 1 + 2 + 3 + 4) - (Mapping 1 + 1 + 1 + 1
`
`Transmission
`Number
`
`Symbol
`(i191292)
`
`Mean
`LLR (i)
`
`Mean
`LLR (i2)
`
`Mean
`LLR(i)
`
`Mean
`LLR (i2)
`
`1
`
`1
`
`2
`
`2
`
`Oq10q2
`Oq192
`q10q2
`ClC2
`Oq10q2
`Oq192
`q10q2
`ClC2
`Oq10q2
`Oq192
`q10q2
`ClC2
`Oq10q2
`Oq192
`q10q2
`ClC2
`Oq10q2
`Oq192
`q10q2
`ClC2
`
`-A
`-3A
`A
`3A
`-A
`-A
`A
`A
`-A
`-A
`A
`A
`-3A
`-A
`3A
`A
`-6A
`-6A
`6A
`6A
`
`-A
`A
`-A
`A
`-3A
`3A
`-A
`A
`-A
`A
`-3A
`3A
`-A
`A
`-A
`A
`-6A
`6A
`-6A
`6A
`
`-A
`-3A
`A
`3A
`-A
`-3A
`A
`3A
`-A
`-3A
`A
`3A
`-A
`-3A
`A
`3A
`-4A
`-12A
`4A
`12A
`
`-A
`A
`-A
`A
`-A
`A
`-A
`A
`-A
`A
`-A
`A
`-A
`A
`-A
`A
`-4A
`4A
`-4A
`4A
`
`

`

`Case 1:21-cv-00075-UNA Document 1-2 Filed 01/26/21 Page 13 of 16 PageID #: 44
`
`US 7,567,622 B2
`
`8
`FEC encoder are Subsequently Supplied to a mapping unit 13
`acting as a modulator to output symbols formed according to
`the applied modulation scheme stored as a constellation pat
`tern in a table 15. Subsequently the. data symbols are applied
`to a transmission unit 30 for transmission over the branches
`40A-C. The receiver 20 receives the data packets by the
`receiving unit 35. The bits are then input into a demapping
`unit 21 which acts as a demodulator using the same signal
`constellation, pattern stored in the table 15 which was used
`during the modulation of these bits.
`The demodulated data packets received over one diversity
`branch are stored in a temporary buffer 22 for subsequent
`combining in a combining unit 23 with the data packets
`received over at least one other diversity branch.
`A retransmission is launched by an automatic repeat
`request issued by an error detector (not shown) and commu
`nicated by a communication section 57 of the receiver 20 to a
`receiving section 55 of the transmitter 10 with result that an
`identical data packet is transmitted from the transmitter 10. In
`the combining unit 23, the previously received erroneous data
`packets are soft-combined with the retransmitted data pack
`ets. Then a decoder decodes the bits and output a measure for
`the transmission quality, e.g. the bit-error-rate BER.
`As illustrated in FIG. 5, table 15 stores a plurality of signal
`constellation patterns #0 . . . in which are selected for the
`individual transmissions over the individual diversity
`branches and HARQ transmissions according to a predeter
`mined scheme. The scheme, i.e. the sequence of signal con
`Stellation patterns used for modulating/-demodulating are
`either pre-stored in the transmitter and the receiver or are
`signalled by transmitter to the receiver prior to usage.
`The invention claimed is:
`1. An ARQ re-transmission method in a wireless commu
`nication system wherein data packets are transmitted from a
`transmitter to a receiver using a higher order modulation
`scheme wherein more than two data bits are mapped onto one
`data symbol to perform a first transmission and at least a
`second transmission based on a repeat request, the method
`comprising:
`modulating data packets at the transmitter using a first
`mapping of said higher order modulation scheme to
`obtain first data symbols:
`performing the first transmission by transmitting the first
`data symbols over a first diversity branch to the receiver;
`receiving at the transmitter the repeat request issued by the
`receiver to retransmit the data packets in case the data
`packets of the first transmission have not been success
`fully decoded;
`modulating, in response to the received repeat request, said
`data packets at the transmitter using a second mapping of
`said higher order modulation scheme to obtain second
`data symbols;
`performing, in response to the received repeat request, the
`second transmission by transmitting the second data
`symbols over a second diversity branch to the receiver;
`demodulating the received first and second data symbols at
`the receiver using the first and second mappings respec
`tively; and
`diversity combining the demodulated data received over
`the first and second diversity branches, wherein:
`the first and second mapping of said higher order modula
`tion schemes are pre-stored in a memory table.
`2. The method according to claim 1, wherein properties of
`the first and second mappings are obtained by (a) interleaving
`positions of the bits, in the bit sequence of the modulation
`scheme or (b) inverting bit values of the bits in the bit series of
`the modulation scheme.
`
`7
`If the constellation rearrangement is performed by apply
`ing different mapping schemes, one would end up in employ
`ing a number of different mappings as given in FIG. 1, FIG. 2
`and FIG.3. If the identical mapper (e.g. FIG.1) should be kept
`for all transmit diversity branches, e.g. mapping 2 can be
`obtained from mapping 1 by the following operations:
`exchange positions of original bits i and is
`exchange positions of original bits q and q.
`logical bit inversion of original bits i and q
`Alternatively, those bits that end in positions 1 and 2 can
`also be inverted (resulting in a different mapping with an
`identical bit-reliability characteristics). Accordingly, map
`ping 2 can be obtained from mapping 1, using an interleaver/
`inverter section 14 (see FIG. 6) which performs interleaving
`and/or inverting of the bits.
`Therefore, the following table provides an example how to
`obtain mappings 1 to 4 (or mappings with equivalent bit
`reliabilities for i, i, q and q), where the bits always refer to
`the first transmission, and a long dash above a character
`denotes logical bit inversion of that bit:
`
`TABLE 5
`
`Alternative implementation of the Constellation Rearrangement
`by interleaving (intra-symbol interleaving) and logical inversion
`of bits mapped onto the modulation symbols
`
`Mapping No.
`
`Interleaver and Inverter functionality
`
`1
`2
`3
`4
`
`.
`19292
`12921.191 or 1292.191
`1292.191 or 1292.19
`ICl2C2Orl Cl2C2
`
`10
`
`15
`
`25
`
`30
`
`35
`
`Generally at least 2 different mappings should be
`employed for N>1 diversity branches, where the order and the
`selection of the mappings is irrelevant, as long as the bit
`reliability averaging process, meaning the reduction in differ
`ences in bit reliabilities) is maintained.
`Preferred realizations in terms of number of employed
`mappings
`M-QAM
`Employing log2(M) different mappings
`Employing log(M)/2 different mappings
`M-PSK
`Employing log2(M) different mappings
`Employing log(M)/2 different mappings
`Employing 2log(M) different mappings
`The applied signal constellation mappings for modulation
`at the transmitter and demodulation at the receiver need to
`match for each individual transmit diversity branch. This can
`be achieved by appropriate signalling of parameters indicat
`ing the proper mapping or combination of mappings to be
`applied for the diversity branches and HARQ transmissions.
`Alternatively the definition of the mappings to be applied for
`transmit diversity branches and HARQ transmissions may be
`system predefined.
`FIG. 4 shows an exemplary embodiment of a communica
`tion system according to the present invention. More specifi
`cally, the communication system comprises a transmitter 10
`and a receiver 20 which communicate through a communi
`cation channel consisting of a plurality of diversity branches
`40A, 40B and 40C Although three diversity branches are
`illustrated in the figure, it becomes clear to a person skilled in
`the art that an arbitrary number of branches may be chosen.
`From a data source 11, data packets are supplied to a FEC
`encoder 12, preferably a FEC Turbo encoder, where redun
`dancy bits are added to correct errors. The bits output from the
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`

`

`Case 1:21-cv-00075-UNA Document 1-2 Filed 01/26/21 Page 14 of 16 PageID #: 45
`
`US 7,567,622 B2
`
`10
`9
`positions of the bits, in the bit sequence of the modulation
`3. An ARQ re-transmission method in a wireless commu
`nication system wherein data packets are transmitted from a
`scheme or (b) inverting bit values of the bits in the bit series of
`transmitter to a receiver using a higher order modulation
`the modulation scheme.
`scheme wherein more than two data bits are mapped onto one
`7. A method of receiving transmissions in accordance with
`data symbol to perform a first transmission and at least a
`an ARQ re-transmission scheme used in a wireless commu
`second transmission based on a repeat request, the method
`nication system in which data packets are transmitted from a
`comprising:
`transmitter using a higher order modulation scheme wherein
`modulating data packets at the transmitter using a first
`more than two data bits are mapped onto one data symbol to
`mapping of said higher order modulation scheme to
`perform a first transmission and at least a second transmission
`10 based on a repeat request, wherein the transmitter modulates
`obtain first data symbols:
`data packets using a first mapping of said higher order modu
`performing the first transmission by transmitting the first
`lation scheme to obtain first data symbols, performs said first
`data symbols over a first diversity branch to the receiver;
`transmission by transmitting the first data symbols Over a first
`receiving at the transmitter the repeat request issued by the
`diversity branch to the receiver, modulates the data packets
`receiver to retransmit the data packets in case the data
`packets of the first transmission have not been success- 15 using a second mapping of Said higher order modulation
`fully decoded;
`scheme to obtain second data symbols, and performs said
`modulating, in response to the received repeat request, said
`second transmission by transmitting the second data symbols
`data packets at the transmitter using a second mapping of
`OVer a second diversity branch to the receiver, said method
`said higher order modulation scheme to obtain second
`PS3
`data symbols;
`20
`demodulating the received first data symbols using the first
`performing, in response to the received repeat request, the
`mapp1ng,
`second transmission by transmitting the second data
`communicating, to the transmitter, the repeat request to
`symbols over a second diversity branch to the receiver;
`retransmit the data packets if the demodulated first data
`demodulating the received first and second data symbols at
`symbols are not successfully decoded;
`the receiver using the first and second mappings respec-
`demodulating, based upon the repeat request, the received
`tively; and
`second data symbols using the second mapping; and
`diversity combining the demodulated data received over
`diversity combining, based upon the repeat request, the
`the first and second diversity branches, wherein:
`demodulated data received over the first and second
`the first and second mapping of said higher order modula- 30
`diversity branches, wherein:
`tion schemes are si