`
`(12) United States Patent
`HammarWall et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 9,509,440 B2
`Nov. 29, 2016
`
`(54) METHOD AND RADIO NODE FOR
`ENABLING USE OF HIGH ORDER
`
`(56)
`
`References Cited
`
`COMMUNICATION WITH A USER
`EQUIPMENT
`
`ck
`2015,0358111 A1* 12/2015 Marinier ............... H04, 1999,
`
`(71) Applicant: Telefonaktiebolaget LM Ericsson
`(publ), Stockholm (SE)
`
`(72) Inventors: David Hammarwall, Vallentuna (SE):
`Meng Wang, Solna (SE)
`
`(*) Notice:
`
`(73) Assignee: Telefonaktiebolaget LM Ericsson
`(publ), Stockholm (SE)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 56 days.
`(21) Appl. No.:
`14/390,904
`
`(22) PCT Filed:
`(86). PCT No.:
`S 371 (c)(1),
`(2) Date:
`
`Jun. 26, 2014
`PCT/SE2014/050803
`
`Oct. 6, 2014
`
`(87) PCT Pub. No.: WO2015/020587
`PCT Pub. Date: Feb. 12, 2015
`
`(65)
`
`Prior Publication Data
`
`Dec. 31, 2015
`US 2015/038.131 O A1
`Related U.S. Application Data
`.S. App
`(60) Provisional application No. 61/863.935, filed on Aug.
`9, 2013.
`
`(2006.01)
`(2009.01)
`
`(51) Int. Cl.
`H04L I/00
`H047 72/08
`(52) U.S. Cl.
`CPC ........... H04L I/0005 (2013.01); H04L I/0003
`(2013.01); H04L I/0009 (2013.01);
`(Continued)
`(58) Field of Classification Search
`None
`See application file for complete search history.
`
`FOREIGN PATENT DOCUMENTS
`
`CN
`WO
`WO
`
`102624481 A
`2013 123961 A1
`2014.109915 A1
`
`8, 2012
`8, 2013
`7, 2014
`
`OTHER PUBLICATIONS
`
`Panasonic, “Discussion on 256QAM for Downlink in Small Cell
`Deployments”, 3GPP TSG-RAN WG1 Meeting 72bis, Apr. 15,
`2013, pp. 1-6, R1-131328, Chicago, US.
`(Continued)
`
`Primary Examiner — Diane Lo
`y
`(74) Attorney, Agent, or Firm — Coats & Bennett,
`P.L.L.C.
`
`ABSTRACT
`(57)
`A method and radio node (500) for enabling higher-order
`modulation in a radio communication with a first UE (502).
`A first table configuration comprises at least one of a first
`Modulation and Coding Scheme, MCS, table and a first
`Channel Quality Indicator, COI, table which tables support
`a certain maximum modulation order. When the radio node
`(500) detects that a modulation order higher than the maxi
`mum modulation order of the first table configuration is
`potentially possible to use in the radio communication, the
`radio node (500) instructs the first UE (502) to apply a
`second table configuration which comprises at least one of
`a second MCS table and a second CQI table which second
`tables Support the higher modulation order. At least one
`entry for at least one modulation order in the tables of the
`first table configuration is maintained in the tables of the
`second table configuration as a fall-back in case it is desir
`able to use the at least one modulation order of the first table
`configuration when the second table configuration is
`applied. Thereby, a higher data rate can be achieved in the
`radio communication.
`
`28 Claims, 7 Drawing Sheets
`
`Samsung Ex. 1001
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`
`
`US 9,509,440 B2
`Page 2
`
`(52) U.S. Cl.
`CPC ........... H04LI/00II (2013.01); H04L I/0016
`(2013.01); H04L I/0025 (2013.01); H04L
`I/0026 (2013.01); H04W 72/082 (2013.01)
`References Cited
`
`(56)
`
`OTHER PUBLICATIONS
`Huawei, et al., “Standard Impacts to Support Higher Order Modu
`lation”, 3GPP TSG-RAN WG1 Meeting 73, May 20, 2013, pp. 1-2,
`R1-131853, Fukuoka, JP.
`
`HTC, “On Small Cell Enhancement for improved Spectral Effi
`ciency”, 3GPP TSG RAN WG1 Meeting #72, Jan. 28, 2013, pp. 1-4,
`R1-130311, St. Julians, Malta.
`Intel Corporation, “CQI/MCS/TBS Tables for 256QAM and Rel
`evant Signaling”, 3GPP TSG RAN WG1 Meeting #76, Feb. 10,
`2014, pp. 1-8, R1-14.0118, Prague, Czech Republic.
`3rd Generation Partnership Project, “LTE: Evolved Universal Ter
`restrial Radio Access (E-UTRA); Physical layer procedures (3GPP
`TS 36.213 version 11.2.0 Release 11), Technical Specification,
`ETSI TS 136 213 V1.1.2.0, Apr. 1, 2013, pp. 1-175, ETSI, France.
`* cited by examiner
`
`Samsung Ex. 1001
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`
`
`U.S. Patent
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`Nov. 29, 2016
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`Sheet 1 of 7
`
`US 9,509,440 B2
`
`100
`
`MCS
`
`CQI
`
`O 2
`
`MCS
`
`coin O.
`
`UE 1
`
`Fig. 1 (Prior art)
`
`
`
`|
`
`|
`
`||
`
`||
`
`||
`
`||
`
`MCS Index Modulation Order TBS Index
`MCS
`Qm
`TBs
`0
`2
`0
`1
`2
`1
`2
`2
`2
`3
`2
`3
`4
`2
`4
`5
`2
`5
`6
`2
`6
`7
`2
`7
`8
`2
`8
`9
`2
`9
`10
`4
`9
`11
`4
`10
`12
`4
`11
`13
`4
`12
`14
`4
`13
`15
`4
`14
`16
`4
`15
`17
`6
`15
`18
`6
`16
`19
`6
`17
`20
`6
`18
`21
`6
`19
`22
`6
`20
`23
`6
`21
`24
`6
`22
`25
`6
`23
`26
`6
`24
`27
`6
`25
`28
`6
`26
`29
`2
`30
`4
`reserved
`31
`6
`
`Fig. 2
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`U.S. Patent
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`Nov. 29, 2016
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`Sheet 2 of 7
`
`US 9,509,440 B2
`
`
`
`a
`
`6
`8
`9
`
`QPSK
`16QAM
`16QAM
`
`12
`
`64QAM |
`
`area
`
`602
`490
`616
`
`666
`
`| 1.1758
`19141
`2.4063
`
`3.9023
`
`Fig. 3
`
`Samsung Ex. 1001
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`
`
`U.S. Patent
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`Nov. 29, 2016
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`Sheet 3 of 7
`
`US 9,509,440 B2
`
`400
`
`Detecting that higher modulation order
`is possible to use for first UE
`
`Instruct first UE to apply second table configuration
`Supporting higher modulation order
`
`Fig. 4
`
`402
`
`
`
`Communication
`Circuit
`
`MCS
`
`502
`
`Fig. 5
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`Samsung Ex. 1001
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`U.S. Patent
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`Nov. 29, 2016
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`Sheet 4 of 7
`
`US 9,509,440 B2
`
`600
`
`Receive instruction to apply second table
`configuration Supporting higher modulation order
`
`602
`
`Apply Second table configuration
`in radio communication
`
`Fig. 6
`
`
`
`Communication
`Circuit
`
`702
`
`Instruction
`
`MCS
`
`CQI
`
`Processor
`
`700a.
`
`700b
`
`Samsung Ex. 1001
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`U.S. Patent
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`Nov. 29, 2016
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`Sheet S of 7
`
`US 9,509,440 B2
`
`MCS Index Modulation Order TBS Index
`MCs
`Qm
`TBS
`
`i
`t
`t
`H H H
`
`
`
`|
`
`||
`5
`e
`||
`7-1
`8-2
`||
`9-3
`404 |
`145 ||
`426
`43-7
`||
`448 I
`459
`46- 10
`||
`47 11 ||
`48- 12
`||
`49 13
`||
`2014 ||
`24, 15
`22 16
`||
`23-17
`|
`24–18
`25- 19
`||
`26-20
`||
`27-21
`||
`28-22
`||
`23
`24
`25
`26
`27
`28
`29
`30
`31
`
`||
`||
`||
`
`2
`2
`2
`2
`2
`4
`4
`4
`4
`4
`4
`4
`6
`6
`6
`6
`6
`6
`6
`6
`6
`6
`6
`6
`8
`8
`8
`8
`8
`8
`2
`4
`6
`
`|
`|
`|
`|
`
`||
`||
`||
`||
`||
`||
`
`5
`5.
`e
`7
`8
`9
`9
`10
`11
`12
`13
`14
`15
`15
`16
`17
`18
`19
`20
`21
`22
`23
`24
`25
`26
`New index
`New index
`|| New index
`|| New index
`|| New index
`New index
`reserved
`
`||
`||
`||
`||
`|
`||
`||
`||
`||
`||
`||
`
`Fig. 8
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`Samsung Ex. 1001
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`Sheet 6 of 7
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`US 9,509,440 B2
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`
`
`CQl index
`
`Code rate x 1024 officiency
`
`QPSK
`QPSK
`QPSK
`QPSK
`
`4
`5
`
`428
`
`64QAM
`
`78
`420
`193
`308
`449
`
`67
`666
`
`0.2344
`0.3770
`0-6046
`0.870
`
`14766
`
`3.9023
`4.5234
`5.1 152
`5.5547
`
`Fig. 9
`
`Samsung Ex. 1001
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`
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`U.S. Patent
`
`Nov. 29, 2016
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`Sheet 7 Of 7
`
`US 9,509,440 B2
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`2984 || 3112
`. . . . . 2984
`. .
`. . .
`400s 400s 400s
`
`12960 13536
`15264 15264
`
`13536
`
`15264
`
`
`
`TBS
`o
`
`16 || 2 | so I 88
`24
`sé
`ss
`144
`32
`72
`44
`476
`40
`104
`176
`20s
`
`76
`
`256
`
`H 328
`392 H
`680 HCH
`
`136
`
`144
`
`296
`
`328
`
`456
`
`504
`
`616
`
`...
`
`208 I 440 | 680
`224
`488
`744
`280
`600
`904
`336
`696
`1064
`
`904 . . .
`1000
`1224
`1416
`
`17568
`
`992 16992
`1908O
`22 152 22 152
`
`: O 8 O
`24496 E. 2 7 3 7 6
`
`22 152
`
`24496 25.456
`28336 28336
`30576 31704 31704
`32856 340O8 34008
`
`3516O 3560 3560
`
`3 9 2 3 2
`3 9 2 3 2
`42368 4386 4386
`
`440
`488
`520
`552
`584
`
`904
`1000
`1064
`1128
`1192
`
`1384
`1480
`1608
`1736
`1800
`
`46888 46888 46888
`51024 5 1024 5 1024
`...
`1864
`55056 55056 55056
`1992 . . . .
`2152 . . . . . . 59256 59256 59256
`2280 . . . . . . 61664 61664 63776
`2408 . . . . . . 66592 66592 66592
`
`2
`22
`
`NV
`NV
`
`NV
`NV
`
`NV
`NV
`
`NV
`NV
`
`. . . . NV
`...
`. . . . . NV
`
`NV
`NV
`
`NV
`NV
`
`Samsung Ex. 1001
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`US 9,509,440 B2
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`1.
`METHOD AND RADIO NODE FOR
`ENABLING USE OF HIGH ORDER
`MODULATION IN A RADIO
`COMMUNICATION WITH A USER
`EQUIPMENT
`
`TECHNICAL FIELD
`
`The present disclosure relates generally to a radio node of
`a cellular network, a User Equipment, UE and methods
`therein, for enabling use of a high order modulation when
`communicating radio signals.
`
`10
`
`BACKGROUND
`
`15
`
`In this field, the term “User Equipment, UE is commonly
`used and will be used in this disclosure to represent any
`wireless terminal or device capable of radio communication
`with a cellular network including receiving downlink signals
`transmitted from a serving radio node and sending uplink
`signals to the radio node. For example, the term User
`Equipment, UE could be exchanged by the term "wireless
`device'. Further, the term “radio node', also commonly
`referred to as a base station, e-nodeB, eNB, etc., represents
`any node of a cellular network that can communicate uplink
`and downlink radio signals with UEs. The radio nodes
`described here may, without limitation, include so-called
`macro nodes and low power nodes such as micro, pico,
`femto, Wifi and relay nodes, to mention some customary
`examples. Throughout this disclosure, the term “eNB' is
`often used but can be exchanged by the term radio node.
`Link adaptation in systems according to Long Term
`Evolution, LTE, is based on adaptive modulation and cod
`ing, which controls data rate by adaptively adjusting the
`modulation scheme and/or channel coding rate according to
`the radio-link conditions. In this procedure, the Modulation
`and Coding Scheme, MCS, adopted for Physical Downlink
`Shared Channel, PDSCH, transmission must be indicated in
`downlink MCS signaling by the serving radio node to the
`UE. By uplink signaling, the UE informs the radio node
`about corresponding radio-link, i.e. channel, conditions
`through Channel Quality Indicator, COI signaling, including
`sending CQI reports to the radio node.
`This is generally illustrated in FIG. 1 in which a radio
`node 100 of a cellular network is serving two UEs denoted
`UE1 and UE2. In this example, UE1 and UE2 both report
`quality measurements made on the channel used by sending
`CQI reports to the radio node 100 which selects a suitable
`MCS for each UE based on their CQI reporting and signals
`the selected MCS to the UEs, respectively. Link adaptation
`is made in this way for individual UEs on a dynamic basis
`since the radio-link conditions may change rapidly. The
`selection of a suitable MCS can thus be made individually
`for each UE.
`In current LTE systems, the set of available modulation
`schemes for both downlink and uplink includes Quadrature
`Phase-Shift Keying, QPSK, 16 Quadrature Amplitude
`Modulation, QAM, and 64QAM, corresponding to two, four
`and six bits carried per modulation symbol, respectively. In
`this field, the number of bits carried per modulation symbol
`is usually referred to as the modulation order, Q.
`In brief, the serving radio node selects a suitable MCS
`based on CQI reporting from the UE and signals the selected
`MCS to the UE with reference to a predefined MCS index
`table which is known to the UE. The MCS index table maps
`MCS indices to modulation order and a Transport Block
`Size, TBS, index. Further, the UE determines a COI value
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`based on signal measurements and the CQI is signaled from
`the UE to the radio node with reference to a likewise
`predefined CQI index table which maps CQI indices to
`modulation forms and code rates. In this description, the
`term “modulation form' is used for short to indicate a
`modulation format, method or scheme.
`In LTE, especially for scenarios with good channel con
`ditions where the Signal-to-Interference-and-Noise Ratio,
`SINR, is high, e.g. in small-cell environments where the UE
`is close to its serving radio node, a straightforward means to
`provide higher data rate for the UE with given transmission
`bandwidth is to use higher-order modulation that allows for
`more bits of information to be carried per modulation
`symbol, as compared to the modulation schemes mentioned
`above where the highest possible data rate is provided by
`64QAM carrying six bits per modulation symbol. However,
`it is a problem that the control signaling schemes, methods,
`formats or protocols of today do not support any modulation
`with higher order than six bits per symbol, as in 64OAM. It
`is also a problem that additional control signaling would be
`required between the UE and the serving radio node if higher
`data rate is to be achieved by using higher-order modulation.
`
`SUMMARY
`
`It is an object of embodiments described herein to address
`at least some of the problems and issues outlined above. It
`is possible to achieve this object and others by using a radio
`node, a UE and methods therein as defined in the attached
`independent claims.
`According to one aspect, a method is performed by a radio
`node of a cellular network. The radio node is operable to
`apply a first table configuration in radio communications
`with User Equipments, UEs, the first table configuration
`comprising at least one of a first Modulation and Coding
`Scheme, MCS, table and a first Channel Quality Indicator,
`CQI, table wherein the at least one of the first MCS table and
`the first CQI table support a certain maximum modulation
`order.
`In this method, the radio node detects that a higher
`modulation order which is higher than the maximum modu
`lation order of the first table configuration is potentially
`possible to use in a radio communication between the radio
`node and a first UE. The radio node then instructs the first
`UE to apply a second table configuration in the radio
`communication. The second table configuration comprises
`at least one of a second MCS table and a second CQI table
`wherein the at least one of the second MCS table and the
`second CQI table support the higher modulation order.
`Furthermore, at least one entry for at least one modulation
`order in the at least one of the first MCS table and the first
`CQI table is maintained in the at least one of the second
`MCS table and the second CQI table as a fall-back in case
`it is desirable to use the at least one modulation order in the
`at least one of the first MCS table and the first CQI table
`when the second table configuration is applied.
`According to another aspect, a radio node of a cellular
`network is operable to apply a first table configuration in
`radio communications with User Equipments, UEs, the first
`table configuration comprising at least one of a first Modu
`lation and Coding Scheme, MCS, table and a first Channel
`Quality Indicator, COI, table wherein the at least one of the
`first MCS table and the first CQI table support a certain
`maximum modulation order. The radio node comprises a
`logic unit configured to detect that a higher modulation order
`which is higher than the maximum modulation order of the
`
`Samsung Ex. 1001
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`US 9,509,440 B2
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`3
`
`4
`
`BRIEF DESCRIPTION OF DRAWINGS
`
`first table configuration is potentially possible to use in a The above methods and nodes may be configured and
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`radio communication between the radio node and a first UE. implemented according to different optional embodiments to
`
`
`
`
`
`
`The radio node also comprises an instructing unit configaccomplish further features and benefits, to be described
`
`
`
`ured to instruct the first UE to apply a second table conbelow.
`
`
`figuration in the radio communication, the second table 5
`
`
`
`configuration comprising at least one of a second MCS table
`
`
`
`
`and a second CQI table wherein the at least one of the second
`The solution will now be described in more detail by
`
`
`
`
`
`
`MCS table and the second CQI table support the higher
`
`
`
`means of exemplary embodiments and with reference to the
`
`
`modulation order. At least one entry for at least one modu
`
`
`accompanying drawings, in which:
`
`
`lation order in the at least one of the first MCS table and the 10
`
`
`
`
`FIG. 1 is a communication scenario illustrating how link
`
`
`
`first CQI table is maintained in the at least one of the second
`
`
`
`adaptation can be achieved, according to the prior art.
`
`
`
`MCS table and the second CQI table as a fall-back in case
`
`FIG. 2 is a table used for MCS sign aling from a radio node
`
`
`
`it is desirable to use the at least one modulation order in the
`
`
`to a UE, according to a first table configu ration.
`
`
`
`
`at least one of the first MCS table and the first CQI table
`
`
`FIG. 3 is a table used for CQI sign aling from a UE to a
`15
`
`when the second table configuration is applied.
`
`
`radio node, according to the first table configuration.
`
`
`
`
`According to another aspect, a method is performed by a
`
`
`
`FIG. 4 is a flow chart illustrating a procedure in a radio
`User Equipment, UE, being operable to apply a first table
`
`
`
`
`
`node, according to some possible embodiments.
`configuration in a radio communication with a radio node of
`
`
`
`
`
`FIG. 5 is a block diagram illustrating an example of how
`
`
`
`
`a cellular network. The first table configuration comprises at
`
`
`20 a radio node may be configu red and operate, according to
`
`
`
`
`least one of a first Modulation and Coding Scheme, MCS,
`
`further possible embodiments.
`
`
`table and a first Channel Quality Indicator, CQI, table
`FIG. 6 is a flow chart illustrating a procedure in a UE,
`
`
`
`
`
`
`
`
`wherein the at least one of the first MCS table and the first
`
`
`according to some possible embodiments.
`
`
`
`
`CQI table support a certain maximum modulation order. In
`
`
`
`
`FIG. 7 is a block diagram illustrating an example of how
`
`
`
`this method, the UE receives an instruction from the radio
`
`
`
`25 a UE may be configured and operate, according to further
`
`
`
`in the radio node to apply a second table configu ration
`
`possible embodiments.
`
`
`communication, the second table configuration comprising
`
`
`FIG. 8 is an example of a modified table used for MCS
`
`at least one of a second MCS table and a second CQI table
`
`
`
`signaling from a radio node to a UE, according to according
`
`
`wherein the at least one of the second MCS table and the
`to a second table configuration.
`
`
`
`
`second CQI table support a higher modulation order which 30
`
`
`FIG. 9 is an example of a modified table used for CQI
`is higher than the maximum modulation order of the first
`
`
`
`
`
`
`signaling from a UE to a radio node, according to the second
`
`second table applies the table configu ration. The UE further
`
`
`table configuration.
`configuration in the radio communication with the radio
`
`
`
`
`FIG. 10 is an example of a modified table used for
`node.
`
`
`
`mapping a Transport Block Size, TBS, index to a data rate,
`
`According to another aspect, a User Equipment, UE, is
`
`
`
`
`
`35 according to further possible embodiments.
`in a radio operable to apply a first table configu ration
`
`
`
`
`
`communication with a radio node of a cellular network, the
`
`
`
`first table configuration comprising at least one of a first
`Modulation and Coding Scheme, MCS, table and a first In this solution it has been recognized that the above
`
`
`
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`can Channel Quality Indicator, CQI, table wherein the at least 40 described control sign aling for MCS and CQI indication
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`one of the first MCS table and the first CQI table support a be re-designed in order to adopt higher-order modulation
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`certain maximum modulation order. The UE comprises a schemes in LTE systems. In particular, the MCS and CQI
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`such can be modified used for such signaling an index tables communication unit which is configu red to receive
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`instruction from the radio node to apply a second table that the current maximum modulation order can be increased
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`this disclosure, configuration in the radio communication, the second table 45 without requiring any extra sign aling bits. In
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`configuration comprising at least one of a second MCS table the term higher-order modulation may refer to modulation
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`and a second CQI table wherein the at least one of the second schemes that are higher than 64QAM, such as e.g. 256QAM
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`MCS table and the second CQI table support a higher allowing eight bits per symbol, or even higher modulation of
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`modulation order which is higher than the maximum modu512QAM, and so forth.
`is initially a first table configuration Briefly described, The UE also 50 lation order of the first table configu ration.
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`comprises a logic unit which is configured to apply the applied in radio communication between a radio node and a
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`comprises a first MCS table second table configuration in the radio communication with UE. The first table configu ration
`the radio node.
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`and/or a first CQI table which tables support a certain
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`When using any of the above methods and nodes, it is maximum modulation order, e.g. 6. An example of the first
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`possible to achieve a higher data rate in the radio commu55 MCS table is shown in FIG. 2 and an example of the first
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`nication between the radio node and the UE by using the CQI table is shown in FIG. 3. The first MCS table and the
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`higher modulation order of the second table configuration, first CQI table are thus predefined and known to the UE, for
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`e.g. when the radio or channel conditions are favorable,example the tables currently used in LTE for signaling
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`instead of being limited to the maximum modulation orderbetween radio nodes and UEs for enabling link adaptation as
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`of the first table configu ration.
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`60 described above although other MCS and CQI tables are
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`A computer program is also provided
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`also possible comprising instruc to use in the first table configuration. In these
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`tions which, when executed
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`examples it can be seen that the on at least one processor, cause maximum modulation order
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`the at least one processor
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`supported by the to carry out either of the above first MCS table and the first CQI table is
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`methods. A carrier is also provided which contains the above
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`Qm =6 which corresponds to 64QAM.
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`computer program, wherein the carrier is one of an elec-65 When detecting that a higher modulation order which is
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`order of the first table than the maximum modulation higher computer readtronic signal, optical signal, radio sign al, or
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`able storage medium.
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`above possible to use in the configu ration is potentially
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`DETAILED DESCRIPTION
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`Samsung Ex. 1001
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`US 9,509,440 B2
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`communication, e.g. based on COI reports from the UE, the
`radio node instructs the UE to apply a second table con
`figuration that Supports the higher modulation order. The
`second table configuration comprises a second MCS table
`and/or a second CQI table having additional entries that
`Support the higher modulation order. Examples of how Such
`tables of the second table configuration can be configured
`will be described in more detail later below. In this solution,
`at least one entry for at least one modulation order is
`maintained, i.e. kept, from the table(s) of the first table
`configuration as a fall-back in case it would become desir
`able or even necessary to use the least one modulation order
`of the first table configuration when the second table con
`figuration is applied, such as when the radio conditions get
`worse and only the least one modulation order of the first
`table configuration, e.g. the lowest modulation order, is
`possible to use for keeping the radio connection.
`It will now be described how link adaptation can be
`achieved in general according to LTE.
`For downlink data transmission in LTE, the radio node
`typically selects the MCS depending on the CQI feedback
`transmitted by the UE in the uplink, as illustrated in FIG. 1.
`The CQI feedback indicates the present channel condition
`and possible data rate, or more specifically a modulation and
`coding scheme MCS, that can be supported by the downlink
`25
`channel given the present channel condition and UE
`receiver.
`The LTE specifications are designed to provide signaling
`between the radio node and the UE. In the downlink, the
`information about the MCS adopted for PDSCH transmis
`sion is indicated by a five-bit field in the Downlink Control
`Information, DCI, transmitted from the radio node to the
`UE. This MCS field corresponds to the MCS index table
`shown in FIG. 2. In this table, there is room for 32 combi
`nations or entries, where 29 entries are used to signal an
`adopted MCS, each entry corresponding to a modulation
`order and a Transport Block Size, TBS, while 3 entries are
`reserved, e.g., to Support adaptive retransmissions. All pos
`sible TBS can be described by a TBS table mapping a TBS
`index. Its, and an allocation bandwidth into the corre
`40
`sponding transport block size (in bits).
`In the uplink, the UE reports CQI to assist the serving
`radio node to select the appropriate MCS to apply for
`downlink transmissions. Typically, the CQIs are derived
`from measurements made by the UE on downlink reference
`signals transmitted by the serving radio node. For example,
`the reported CQI may represent the highest MCS that is
`supported for a PDSCH transmission, e.g. with a transport
`block error rate probability not exceeding 10%. The CQI is
`signaled from the UE to the radio node with reference to a
`predefined CQI index table, as shown in FIG. 3. A 4-bit CQI
`value corresponds to a particular MCS out of 16 combina
`tions corresponding to COI index 0-15 in the CQI index
`table. It should be noted that the CQI table is parameterized
`in terms of coding rate, as opposed to transport block size.
`Thus, the selected and signaled CQI indicates the highest
`modulation and coding rate at which the block error rate
`measured at UE does not exceed 10%. Based on the CQI
`feedback from the UE and other information, the radio node
`is able to select a proper MCS index from the MCS table and
`notify the UE accordingly by MCS signaling.
`Current LTE systems support three modulation schemes
`for both downlink and uplink: QPSK, 16QAM and 64QAM.
`Accordingly, the MCS index table, the CQI index table and
`the corresponding fields for indication in DCI are designed
`for these three modulation schemes. However, higher-order
`modulation schemes are not supported in current LTE speci
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`fications. In order to Support higher-order modulation, i.e.
`higher than the above schemes QPSK, 16QAM and
`64QAM, UEs must support an additional MCS/COI table
`that also includes specific entries for new modulation
`schemes. The modification of MCS/COI table may require
`re-designing the DCI format and possibly also the Uplink
`Control Information, UCI, format.
`Typically, the additional MCS/CQI tables are used in
`scenarios with high Signal-to-Noise Ratio, SNR, or SINR
`which allow for higher-order modulation to be used thanks
`to the high signal quality. In scenarios with relatively low
`SNR or SINR, on the other hand, the current MCS/CQI
`tables supporting QPSK, 16QAM and 64OAM are useful to
`achieve link robustness. Hence, a solution has been devised
`with flexibility to adopt appropriate MCS/COI tables based
`on channel conditions as follows.
`As mentioned above, current LTE systems only Support
`modulation up to 64QAM, while it may be desirable to use
`higher-order modulation, e.g. 256QAM, to increase the data
`rate when the signal quality allows. To Support higher-order
`modulation, adaptations and/or extensions to the current
`control signaling in terms of the MCS index table, the CQI
`index table and the corresponding fields in DCI/UCI are
`required. This can be solved by the embodiments described
`herein.
`In this disclosure, an alternative design of an MCS index
`table and/or of a COI index table supporting higher-order
`modulation is described which can be used for LTE systems,
`which can be supported in addition to basic MCS and CQI
`tables such as the current design of the MCS index table and
`the CQI index table shown in FIG. 2 and FIG. 3, respec
`tively.
`In the current LTE specification, the MCS and CQI tables
`Support modulation schemes up to 64QAM, e.g. as illus
`trated in FIGS. 2 and 3. The proposed new MCS and CQI
`index tables are able to Support modulation higher than
`64QAM, without necessarily extending the number of bits in
`the DCI/UCI formats, or the number of entries in the MCS
`table and in the CQI table, respectively. In this solution, it is
`possible to select higher-order modulation schemes e.g. in
`the high-SINR scenarios or generally when a performance
`related parameter, Such as SINR, of signals communicated
`between a radio node and a UE is above a certain threshold.
`In the new MCS/COI tables, new entries for higher-order
`modulation are added and designed to provide Sufficient
`resolution to cover the high-SINR region. Meanwhile, a
`large part of the existing entries in current MCS and/or CQI
`tables may be preserved. The current MCS and/or CQI
`tables may be comprised in a first table configuration while
`the new MCS and/or CQI tables supporting a higher-order
`modulation may be comprised in a second table configura
`tion. This has the advantage that the number of new MCS/
`CQI formats a UE and a radio node has to implement may
`be minimized. In other words, the UE and the radio node
`need to support only one extra MCS table and/or CQI table
`of the second table configuration in order to enable the
`higher-order modulation.
`In a possible embodiment, at least one MCS entry, e.g. the
`lowest MCS entry with MCS index 0, in the MCS table
`and/or at least one CQI entry, e.g. the lowest COI entry for
`the lowest coding rate of the lowest modulation order with
`CQI index 1, in the CQI table is preserved or maintained
`from the basic MCS and/or CQI table, to ensure proper
`communication between the radio node and the UE under
`poor channel or radio conditions. Thus, a fallback is pro
`vided in case it is only possible or desirable to use a
`modulation order lower than the higher modulation order,
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`Samsung Ex. 1001
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`e.g. the lowest modulation order, when the second table
`configuration is applied. This provides flexibility and robust
`ness in case of changing channel or radio conditions, and
`provides a robust format to, for example, signal control
`plane data, and/or to reconfigure the UE to assume the basic
`MCS and/or CQI table suitable for poor/normal channel or
`radio conditions. By employing embodiments described
`herein, the link adaption in LTE systems may be enhanced
`to support higher-order modulation schemes, which can
`significantly improve the spectral efficiency e.g. in high
`SINR scenarios, while maintaining robustness in case of
`worsening radio conditions.
`It should be noted that although terminology from 3GPP
`LTE is used in this disclosure to describe various exempli
`fying embodiments, this should not be seen as limiting the
`Scope of usage to only the aforementioned system. Other
`wireless systems, including WCDMA, WiMAX, and Ultra
`Mobile Broadband, UMB, may also benefit from exploiting
`embodiments described herein.
`It should also be noted that terminology Such as radio
`node should be considered non-limiting and in general
`“radio node' could be considered as device 1 and “UE'
`could be considered as device 2 and these two devices may
`communicate with each other over Some radio channel in the
`manner described herein.
`In the following, the solution will be explained in more
`detail by some exemplary embodiments. It should be noted
`that these embodiments are not mutually exclusive. Com
`ponents from one embodiment may be utilized in another
`embodiment wherever appropriate.
`The MCS index table and CQI index table used in current
`LTE specification are shown in FIG. 2 and FIG. 3, respec
`tively. A possible design of alternative MCS and CQI index
`tables will now be described as well as the mechanism by
`which the radio node and the UE can switch between the
`proposed new MCS/CQI tables of the second table configu
`ration and the MCS/COI tables of the first table configura
`tion. It should be noted that the solution is not limited to the
`specific examples of MCS/CQI tables described herein and
`that any MCS/COI tables may be used in accordance with
`the embodiments described herein.
`An example of a procedure, performed by a radio node of
`a cellular network when the solution is employed, will now
`be described with reference to the flow chart in FIG. 4. Some
`possible but non-limiting embodiments will also be
`45
`described which may be used for the radio node. In this
`procedure, it is assumed that the radio node is operable to
`apply a first table configuration in radio communications
`with UEs, and that the first table configuration comprises at
`least one of a first MCS table and a first CQI table wherein
`the at least one of the first MCS table and the first CQI table
`Support a certain maximum modulation order. As said above,
`the maximum modulation order Supported by the currently
`used MCS/CQI tables is Q.F6 which corresponds to
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