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`Exhibit A
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`

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`Case 1:21-cv-00075-UNA Document 1-1 Filed 01/26/21 Page 2 of 15 PageID #: 18
`
`US007 154961B2
`
`(12)
`
`United States Patent
`Wengerter et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,154,961 B2
`Dec. 26, 2006
`
`(54) CONSTELLATION REARRANGEMENT FOR
`ARQ TRANSMIT DIVERSITY SCHEMES
`(75) Inventors: Christian Wengerter, Kleinheubach
`(DE); Alexander Golitschek Edler Von
`Elbwart, Darmstadt (DE); Eiko Seidel,
`Darmstadt (DE)
`
`(73) Assignee:
`
`his Estric Industrial Co.,
`
`6,580,705 B1* 6/2003 Riazi et al. ................. 370,347
`6,769,085 B1* 7/2004 Von Elbwart et al. ...... T14f748
`6,892,341 B1* 5/2005 Golitschek et al. ......... T14f748
`2002.0036980 A 32002 Lundby et al.
`2002/0114398 A1* 8, 2002 Lin et al. .................... 375/253
`(Continued)
`FOREIGN PATENT DOCUMENTS
`1333605
`1, 2002
`
`CN
`
`(*) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(21) Appl. No.:
`(22) PCT Filed
`1C
`
`10/501,906
`Oct. 18, 2002
`c. 18,
`
`PCT/EPO2A11694
`
`(86). PCT No.:
`S 371 (c)(1),
`(2), (4) Date: Dec. 6, 2004
`(87) PCT Pub. No.: WO2004/036818
`PCT Pub. Date: Apr. 29, 2004
`
`(65)
`
`Prior Publication Data
`US 2005/O1933O7 A1
`Sep. 1, 2005
`(51) Int. Cl
`(2006.01)
`tion 7/02
`(52) U.S. Cl. ...................... 375/267; 33,752
`s
`(58) Field of Classification Search ........
`3 75/26.
`375/299, 295, 298,308, 261; 370/349,465;
`714/748, 761, 701, 786
`See application file for complete search history.
`References Cited
`
`(56)
`
`U.S. PATENT DOCUMENTS
`3/2002 Lundby et al. ............. 370,209
`11/2002 Jeong et al. .................. 341,50
`
`6,356,528 B1*
`6,476,734 B1*
`
`Continued
`(
`)
`OTHER PUBLICATIONS
`Wengerter, C et al., “Advanced Hybrid ARQ Technique Employing
`a Signal Constellation Rearrangement,” 2002 IEEE 56", IEEE
`Vehicular 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—Stevens, Davis, Miller &
`Mosher, LLP
`ABSTRACT
`(57)
`An ARQ (re-) transmission method of transmitting data in a
`wireless communication system wherein data packets are
`transmitted from a transmitter to a receiver, using a first
`transmission and a second transmission based on a repeat
`request. The method comprises the steps of modulating data
`at the transmitter using a first signal constellation pattern to
`obtain a first data symbol. The first data symbol is trans
`mitted as the first transmission to the receiver using a first
`diversity branch. Further, the data is modulated at the
`transmitter using a second signal constellation pattern to
`obtain a second data symbol. Then, the second data symbol
`is transmitted as the second transmission to the receive over
`a second diversity branch. Finally, the received first and
`second data symbol data symbol are diversity combined at
`the rece1Ver. The 1Vent1On Turther relates to a transm1tter
`h
`The i
`ion furth
`1
`and a receiver embodied to carry out the method of the
`invention.
`
`11 Claims, 6 Drawing Sheets
`
`/
`SORCE
`
`2
`FC
`ECCR
`
`3.
`
`MAPNG
`UN
`
`1.
`
`3.
`
`RANSISSION
`UN
`
`
`
`
`
`
`
`
`
`FEC
`ECOER
`
`
`
`MPORARY
`BUFFER
`
`408
`
`

`

`Case 1:21-cv-00075-UNA Document 1-1 Filed 01/26/21 Page 3 of 15 PageID #: 19
`
`US 7,154,961 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
`2003/0048857 A1* 3/2003 Onggosanusi et al. ...... 375,267
`FOREIGN PATENT DOCUMENTS
`
`EP
`EP
`WO
`
`O735701
`1172.959
`O2O67491
`
`10, 1996
`1, 2002
`8, 2002
`
`OTHER PUBLICATIONS
`“Enhanced HARQ Method with Signal Constellation Rearrange
`1 Meeting, No. 19,
`ment.” TSG-RAN Working Group
`XP002229383, Feb. 27, 2001.
`
`Aik, C. et al., “Bit-Interleaved Coded Modulation with Signal Space
`Diversity in Rayleigh Fading.” Signals, Systems, and Computers,
`Conference Record of the Thirty-Third Asilomar Conference,
`Piscataway, NJ, IEEE, XP 010373787, pp. 1003-1007, Oct. 24,
`1999.
`Le Goff, S. et al., “Turbo-Codes and High Spectral Efficiency
`Modulation.” Telecom Bretagne, France Telecom University, IEEE,
`XP 010608782, pp. 645-649, 1994.
`Chinese Office Action dated Mar. 3, 2006 with English translation.
`
`* cited by examiner
`
`

`

`Case 1:21-cv-00075-UNA Document 1-1 Filed 01/26/21 Page 4 of 15 PageID #: 20
`
`U.S. Patent
`
`Dec. 26, 2006
`
`Sheet 1 of 6
`
`US 7,154,961 B2
`
`lm
`1011
`1001 OOO1 OO11
`O O O O
`
`92
`
`100 000 0000 000
`
`
`
`10 1100 000 0110
`9, 9
`O 00 011
`
`11
`
`Mapping 1 (bit-mapping order: iqlig2)
`
`FIG. 1
`
`

`

`Case 1:21-cv-00075-UNA Document 1-1 Filed 01/26/21 Page 5 of 15 PageID #: 21
`
`U.S. Patent
`
`Dec. 26, 2006
`
`Sheet 2 of 6
`
`US 7,154,961 B2
`
`Im
`O010 1010 1000 0000
`
`O110 110 1100 0100
`O O O O
`
`
`
`O111
`
`1111
`
`110
`
`01.01
`
`O O O O
`001
`1011
`1001
`0001
`
`Mapping 2 (bit-mapping order: iqliq2)
`
`FIG. 2
`
`

`

`Case 1:21-cv-00075-UNA Document 1-1 Filed 01/26/21 Page 6 of 15 PageID #: 22
`
`U.S. Patent
`
`Dec. 26, 2006
`
`Sheet 3 of 6
`
`US 7,154,961 B2
`
`OOOO
`
`
`
`I000 [[00 || IIO I I00 I
`
`
`
`
`
`0001 0000 | 0100 0101
`
`OOOO
`
`QOOO
`
`?010 III 0 || III I IOI I
`
`OOOO
`
`00[0 0 [[0 || 0 III 00? ?
`
`
`
`[00 I I000 | [[00 [[0I
`
`OOOO
`
`
`
`IOI I I0 I0 | [[IO [IIIIb O O | O O
`
`
`
`
`
`0000 OI00 | 0{0I 000 I ULII
`
`
`
`----|-
`
`
`
`00II 0010 | 0{{0 0? II
`
`

`

`Case 1:21-cv-00075-UNA Document 1-1 Filed 01/26/21 Page 7 of 15 PageID #: 23
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`Case 1:21-cv-00075-UNA Document 1-1 Filed 01/26/21 Page 8 of 15 PageID #: 24
`
`U.S. Patent
`
`Dec. 26, 2006
`
`Sheet S of 6
`
`US 7,154,961 B2
`
`
`
`
`
`

`

`Case 1:21-cv-00075-UNA Document 1-1 Filed 01/26/21 Page 9 of 15 PageID #: 25
`
`U.S. Patent
`
`
`
`
`
`
`
`
`
`/y/HAVETHELNI | Sllº
`
`

`

`Case 1:21-cv-00075-UNA Document 1-1 Filed 01/26/21 Page 10 of 15 PageID #: 26
`
`1.
`CONSTELLATION REARRANGEMENT FOR
`ARQ TRANSMIT DIVERSITY SCHEMES
`
`US 7,154,961 B2
`
`FIELD OF THE INVENTION
`
`The present invention relates generally to ARQ (re-)
`transmission techniques in wireless communication systems
`and in particular to a method, transceiver and receiver using
`transmit diversity Schemes wherein data packets are trans
`mitted using a first and a second transmission based on a
`repeat request, and the bit-to-symbol mapping is performed
`differently for different transmitted diversity branches. The
`invention is particularly applicable to systems with unreli
`able and time-varying channel conditions resulting in an
`improved performance avoiding transmission errors.
`
`10
`
`15
`
`BACKGROUND OF THE RELATED ART
`
`25
`
`30
`
`35
`
`45
`
`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)
`diversity branches “by default' without explicitly requesting
`(by a feedback channel) further diversity branches (as done
`in an ARQ scheme by requesting retransmissions). For
`example the following schemes are considered as transmit
`diversity:
`Site Diversity: The transmitted signal originates from
`different sites, e.g. different base stations in a cellular
`environment.
`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.
`40
`Multicode Diversity: The transmitted signal is mapped on
`different codes in e.g. a CDMA (Code Division Mul
`tiple 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.
`a 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/
`correction 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 trans
`missions has been disclosed which averages the bit reliabili
`ties over Successively requested retransmissions by means of
`signal constellation rearrangement.
`
`50
`
`55
`
`60
`
`65
`
`2
`As shown therein, when employing higher order modu
`lation formats (e.g. M-PSK, M-QAM with log(M)>2),
`where more than 2 bits are mapped onto one modulation
`symbol, the bits have different reliabilities depending on the
`chosen mapping. This leads for most FEC (e.g. Turbo
`Codes) schemes to a degraded decoder performance com
`pared 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
`combining the diversity branches at the receiver.
`
`SUMMARY OF INVENTION
`
`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 per
`formance at the receiver by applying different signal con
`Stellation mappings to the available distinguishable transmit
`diversity branches and ARQ (re-) transmissions. The inven
`tion 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 mapping 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
`symbol, for a given arbitrary number (N> 1) of available
`diversity branches and required retransmissions the quality
`of the averaging 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 different bits of a data symbol. Although it might
`be that only after using several diversity branches or paths
`a perfect averaging 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 differences. 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 diversity branches
`and/or the number of ARQ transmissions is sufficient to
`perform a perfect averaging. Hence, the averaging should
`then be performed on a best effort basis as shown in the
`example below.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`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 constel
`lations;
`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
`
`

`

`Case 1:21-cv-00075-UNA Document 1-1 Filed 01/26/21 Page 11 of 15 PageID #: 27
`
`3
`FIG. 6 show the communication system according to the
`present invetion with an interleaver/inverter section.
`
`US 7,154,961 B2
`
`DETAILED DESCRIPTION or EMBODIMENT
`EXAMPLES
`
`10
`
`25
`
`35
`
`(3)
`
`where X denotes the in-phase component of the normalized
`received modulation symbol rand K is a factor proportional
`to the signal-to-noise ratio. Under the assumption of a
`uniform signal constellation (x-3X) equations (2) and (3)
`can be fairly good approximated approximated, as shown in
`S. Le Goff, A. Glavieux, C. Berrou, “Turbo-Codes and High
`Spectral 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 Constellation Rearrangement.” IEEE Proceedings of
`VTC 2002 Fall, Vancouver, Canada, September 2002, by
`
`The mean LLR for i and i for a given transmitted
`modulation 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.
`Individual 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 0q11q2 and 1d.1q, where q1 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 i
`equals 1 (leftmost and rightmost columns). Hence, assuming
`a uniform distribution of transmitted modulation symbols,
`on average 50% of the MSBs i have about three times the
`magnitude in LLR of i.
`
`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
`15
`branches and all HARO transmissions (single redundancy
`version Scheme). Then again, an extension to a transmit
`diversity and HARQ scheme transmitting only partly iden
`tical bits on the diversity branches and HARQ transmissions
`can be accomplished. An example for a system using mul
`tiple redundancy versions is described in copending EP
`0.1127244, 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. How
`ever the highest performance gains can be achieved with the
`30
`use of HARQ.
`The following example describes a method with two
`diversity 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,
`usually the received diversity branches are combined at the
`40
`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
`reliability of a demodulated bit b from a received modula
`tion symbol r=x+y is defined as follows:
`
`45
`
`LLR(b) = in Pr; b = 1 t
`
`(1)
`
`50
`
`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).
`
`TABLE 1.
`
`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 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 q and q.
`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
`equations for a Gaussian channel:
`
`55
`
`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 (Mapping 2) according to FIG. 2, which yields the
`mean LLRs given in Table 2.
`
`

`

`Case 1:21-cv-00075-UNA Document 1-1 Filed 01/26/21 Page 12 of 15 PageID #: 28
`
`5
`
`TABLE 2
`
`US 7,154,961 B2
`
`6
`
`TABLE 3-continued
`
`Mean LLRs for bits mapped on the in-phase component of the signal
`constellation for Mapping 2 in FIG. 2.
`
`Symbol
`(i1911292)
`
`Mean
`value of x
`
`Mean
`LLR (i)
`
`Mean
`LLR (i2)
`
`X1
`
`-X
`
`-A
`-A
`A
`A
`
`-3A
`3A
`-A
`A
`
`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
`
`10
`
`15
`
`Diversity Symbol
`Branch (iqi i292)
`2
`Oq10q2
`Oq192
`1910q2
`1911q2
`Combined Oq10q2
`1 + 2 Oglq2
`1910q2
`1911q2
`
`Constellation
`Rearrangement
`Mapping 1 + 2
`
`Prior Art
`No Rearrangement
`Mapping 1 + 1
`
`Mean
`LLR (i)
`-A
`-A
`A
`A
`-2A
`-4A
`2A
`4A
`
`Mean
`Mean
`Mean
`LLR (i2) LLR (i) LLR (i2)
`-3A
`-A
`-A
`3A
`-3A
`A
`-A
`A
`-A
`A
`3A
`A
`-4A
`-2A
`-2A
`-4A
`-6A
`2A
`-2A
`2A
`-2A
`2A
`6A
`2A
`
`Comparing now the soft-combined LLRs of the received
`diversity branches applying the constellation rearrangement
`(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
`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
`systems exhibit a Superior performance. It should be noted,
`that the chosen mappings are non exhaustive and more
`combinations of mappings fulfilling the same requirements
`can be found.
`
`25
`
`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.
`
`Transmit
`
`Diversity Symbol
`Branch (iqi i292)
`
`Oq192
`1910q2
`1911q2
`
`Constellation
`Rearrangement
`Mapping 1 + 2
`
`Prior Art
`No Rearrangement
`Mapping 1 + 1
`
`Mean
`LLR (i)
`-A
`-3A
`A
`3A
`
`Mean
`LLR (i)
`-A
`A
`-A
`A
`
`Mean
`LLR (i)
`-A
`-3A
`A
`3A
`
`Mean
`LLR (i)
`-A
`A
`-A
`A
`
`30
`
`35
`
`40
`
`2" and Further Transmissions:
`In case the 1 transmission has not been successfully
`decoded the receiver requests a retransmission (2" trans
`mission). 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 trans
`missions (possibility to employ 4 different mappings—
`sufficient for 16-QAM). Table 4 compares the LLRs with
`and without applying the proposed Constellation Rearrange
`ment. Having a closer look at the combined LLRs, it can be
`seen that with application of the Constellation Rearrange
`ment the magnitude for all bit reliabilities 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
`
`Constellation
`Rearrangement
`(Mapping 1 +
`2 + 3 + 4
`
`Prior Art
`No Rearrangement
`(Mapping 1 +
`1 + 1 + 1
`
`Transmission Symbol
`Number (iiq.11292)
`
`Mean
`Mean
`LLR (i) LLR (i2)
`
`Mean
`Mean
`LLR (i) LLR (i2)
`
`1
`
`1
`
`2
`
`Oq10q2
`Oq1192
`1910q2
`1911q2
`Oq10q2
`Oq192
`1910q2
`1911q2
`Oq10q2
`Oq192
`1910q2
`1911q2
`
`-A
`-3A
`A
`3A
`-A
`-A
`A
`A
`-A
`-A
`A
`A
`
`-A
`A
`-A
`A
`-3A
`3A
`-A
`A
`-A
`A
`-3A
`3A
`
`-A
`-3A
`A
`3A
`-A
`-3A
`A
`3A
`-A
`-3A
`A
`3A
`
`-A
`A
`-A
`A
`-A
`A
`-A
`A
`-A
`A
`-A
`A
`
`

`

`Case 1:21-cv-00075-UNA Document 1-1 Filed 01/26/21 Page 13 of 15 PageID #: 29
`
`US 7,154,961 B2
`
`7
`
`TABLE 4-continued
`
`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
`
`Constellation
`Rearrangement
`(Mapping 1 +
`2 + 3 + 4
`
`Prior Art
`No Rearrangement
`(Mapping 1 +
`1 + 1 + 1
`
`Diversity
`Branch
`
`Transmission Symbol
`Number (iiq.11292)
`
`Mean
`Mean
`Mean
`Mean
`LLR (i) LLR (i2) LLR (i) LLR (i2)
`
`4
`
`2
`
`Combined
`1 + 2 + 3 + 4
`
`Oq10q2
`Oq192
`1910q2
`1911q2
`Oq10q2
`Oq192
`1910q2
`1911q2
`
`-3A
`-A
`3A
`A
`-6A
`-6A
`6A
`6A
`
`-A
`A
`-A
`A
`-6A
`6A
`-6A
`6A
`
`-A
`-3A
`A
`3A
`-4A
`-12A
`4A
`12A
`
`-A
`A
`-A
`A
`-4A
`4A
`-4A
`4A
`
`25
`
`If the constellation rearrangement is performed by apply
`ing different mapping schemes, one would end up in
`employing 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
`35
`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.
`
`30
`
`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
`
`i91.292
`r -
`12921.191 or 12921.191
`1292.19 or 1292.191
`ICl2C2. Or 1911292
`
`Generally at least 2 different mappings should be employed
`for N>1 diversity branches, where the order and the selec
`tion of the mappings is irrelevant, as long as the bit
`reliability averaging process, meaning the reduction in dif
`ferences in bit reliabilities) is maintained.
`Preferred realizations in terms of number of employed
`mappings
`M-QAM
`Employing log2(M) different mappings
`Employing log2(M)/2 different mappings
`M-PSK
`Employing log2(M) different mappings
`Employing log2(M)/2 different mappings
`Employing 2log (M) different mappings
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`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 indi
`cating 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 HARO transmissions may
`be system predefined.
`FIG. 4 shows an exemplary embodiment of a communi
`cation system according to the present invention. More
`specifically, the communication system comprises a trans
`mitter 10 and a receiver 20 which communicate through a
`communication 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 redundancy bits are added to correct errors.
`The bits output from the 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 pattern 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) with the
`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 packets. 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
`
`

`

`Case 1:21-cv-00075-UNA Document 1-1 Filed 01/26/21 Page 14 of 15 PageID #: 30
`
`US 7,154,961 B2
`
`9
`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
`constellation 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 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
`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,
`modulating said data packets at the transmitter using a
`second modulation scheme to obtain second data sym
`bols;
`performing 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 modulation
`Schemes respectively; and
`diversity combining the demodulated data received over
`the first and second diversity branches, wherein:
`the modulation schemes are 16 QAM and a number of
`30
`log2 (M) modulation schemes are used.
`2. An ARQ re-transmission method in a wireless commu
`nication system wherein data packets are transmitted from a
`transmitter to a receiver using 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
`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,
`modulating said data packets at the transmitter using a
`second modulation scheme to obtain second data sym
`bols;
`45
`performing 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 modulation
`Schemes respectively; and
`diversity combining the demodulated data received over
`the first and second diversity branches, wherein:
`the modulation schemes for the first and second diversity
`branches are selected such that after combining the bits
`of the data packets the differences in magnitude among
`the combined bit reliabilities are reduced.
`3. An ARQ re-transmission method in a wireless commu
`nication system wherein data packets are transmitted from a
`transmitter to a receiver using 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
`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,
`
`50
`
`10
`modulating said data packets at the transmitter using a
`second modulation scheme to obtain second data sym
`bols;
`performing 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 modulation
`Schemes respectively; and
`diversity combining the demodulated data received over
`the first and second diversity branches, wherein:
`the data for transmission is modulated using a single
`redundancy version scheme with an identical data bit
`Sequence.
`4. An ARQ retransmission method in a wireless commu
`nication system wherein data packets are transmitted from a
`transmitter to a receiver using 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
`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,
`modulating said data packets at the transmitter using a
`second modulation scheme to obtain second data sym
`bols;
`performing 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 modulation
`Schemes respectively; and
`diversity combining the demodulated data received over
`the first and second diversity branches, wherein:
`the data for transmission is modulated using a multiple
`redundancy version scheme of partly identical bits.
`5. An ARQ retransmission method in a wireless commu
`nication system wherein data packets are transmitted from a
`transmitter to a receiver using 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
`modulation scheme to obtain fi