US010285150B2
`
`a2) United States Patent
`US 10,285,150 B2
`10) Patent No.:
`
` Baldemairetal. (45) Date of Patent: *May7, 2019
`
`
`(54) METHODS AND ARRANGEMENTSIN A
`TELECOMMUNICATIONS NETWORK
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`(71) Applicant: Telefonaktiebolaget L M Ericsson
`(publ), Stockholm (SE)
`.
`.
`Inventors: Robert Baldemair, Solna (SE); David
`Astely, Bromma (SE); Erik Dahlman,
`Bromma (SE); Ylva Jading, Stockholm
`(SE)
`
`(72)
`
`(73) Assignee: TELEFONAKTIEBOLAGET LM
`ERICSSON (PUBL), Stockholm (SE)
`
`EP
`EP
`
`2008/0013478 Al*
`
`2009/0161654 Al
`2012/0076105 AL*
`
`1/2008 Rangan ou... HO4L 5/0051
`370/328
`
`6/2009 Cai etal.
`3/2012 Yang o...ccccssseeeee HO4L 5/001
`370/329
`
`(*) Notice:
`
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 578 days.
`.
`.
`.
`.
`.
`This patent is subject to a terminal dis-
`claimer.
`(21) Appl. No.: 14/532,781
`(22)
`Filed:
`Nov. 4, 2014
`
`(65)
`
`Prior Publication Data
`US 2015/0103788 Al
`Apr. 16, 2015
`Related U.S. Application Data
`.
`oe
`.
`(63) Continuation of application No. 13/379,602,filed as
`application No. PCT/SE2010/050674 on Jun. 16,
`2010, now Pat. No. 8,902,811.
`(Continued)
`
`(51)
`
`(2009.01)
`(2006.01)
`
`Int. Cl.
`HO4W 56/00
`HOAL 5/00
`(52) U.S. Cl.
`CPC veces HO4W 56/0045 (2013.01); HO4L 5/001
`(2013.01), HO4W 56/0065 (2013.01)
`(58) Field of Classification Search
`CPC vices H04W 56/0005; HO4W 56/00; HO4L
`27/5655; HO4L 27/2675
`See application file for complete search history.
`
`FOREIGN PATENT DOCUMENTS
`
`1/2010
`2148517 Al
`3/2012
`2432286 Al
`(Continued)
`
`OTHER PUBLICATIONS
`
`Unknown, Author,“Draft Report of 3GPP TSG RAN WG? meeting
`466» 3GPP TSG Working Group 2 meeting #66bis, R2-09xxxx,
`Los Angeles, CA, US, Jun. 29-Jul. 3, 2009.
`(Continued)
`Primary Examiner — Romani Ohri
`(74) Attorney, Agent, or Firm — Murphy, Bilak &
`Homiller, PLLC
`ABSTRACT
`(57)
`The present invention relates to methods and arrangements
`in a base station and a user equipment for determining an
`uplink transmission timing correction for communication in
`a telecommunication system in which aggregation of com-
`ponentcarriers is applied. The base station receives a signal
`from the user equipment on an uplink (UL) component
`carrier and measures the arrival time ofthe signal. A timing
`correction ofthe UL transmission timing basedonthearrival
`time of the signal is determined. Thereupon the base station
`determines for which of the uplink componentcarriers used
`by the user equipment the timing correction is valid. The
`timing correction and the validity information is sent to the
`user equipment. The user equipment adjusts the UL trans-
`mission timing for each UL componentcarrier the timing
`correction is valid for.
`
`34 Claims, 7 Drawing Sheets
`
`
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`1
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`APPLE 1001
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`1
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`APPLE 1001
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`US 10,285,150 B2
`Page 2
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`Related U.S. Application Data
`
`(60) Provisional application No. 61/220,844, filed on Jun.
`26, 2009.
`
`(56)
`
`References Cited
`
`FOREIGN PATENT DOCUMENTS
`
`11/2008
`2008277993 A
`JP
`1/2004
`2222102 C2
`RU
`2/2007
`2294059 C2
`RU
`7/1999
`9937037 Al
`WO
`11/2008
`2008133310 Al
`WO
`
`WO 2008156180 Al=12/2008
`WO
`WO 2008156180 Al * 12/2008... HO4W 76/048
`WO
`2009082332 Al
`7/2009
`
`WO 2010148404 AQ=12/2010
`
`OTHER PUBLICATIONS
`
`Unknown, Author, “Issues in Carrier Aggregation”, 3GPP TSG
`RAN WGI Meeting #57bis, R1-092377, Los Angeles, CA, US,Jun.
`29-Jul. 3, 2009.
`Unknown, Author, “PDCCH Design for Carrier Aggregation”,
`Panasonic. 3GPP TSG-RAN WGI Meeting #57; R1-091743. May
`4-8, 2009, San Francisco, California, US, 1-9.
`Unknown, Author, “Reply LS on RAN2 Status on Carrier Aggre-
`gation”, TSG-RAN We4, 3GPP TSG RAN WG4 MEeting #5 bis,
`R4-092488, Jun. 29-Jul. 2, 2009, Los Angeles, California, US, 1-3.
`Unknown, Author, “Views on Remaining Issues on UL Sounding
`RS for E-UTRA”, Motorola, 3GPP TSG RAN WGI #51, R1-074574,
`Nov. 5-9, 2007, Jeju, Korea, 1-7.
`
`* cited by examiner
`
`2
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`

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`US 10,285,150 B2
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`1
`METHODS AND ARRANGEMENTSIN A
`TELECOMMUNICATIONS NETWORK
`
`RELATED APPLICATIONS
`
`This application is a continuation of U.S. application Ser.
`No. 13/379,602, which is the National Stage of International
`Application No. PCT/SE2010/050674,
`filed on 16 Jun.
`2010, and further claimspriority under 35 U.S.C. § 119 from
`the provisional application filed on 26 Jun. 2009 and
`assigned App. No. 61/220,844, and where all such applica-
`tions are incorporated by reference herein.
`
`TECHNICAL FIELD
`
`The present invention relates to arrangements and meth-
`ods in a telecommunications system, and in particular trans-
`mission timing alignmentin a telecommunications system in
`which aggregation of componentcarriers is applied.
`
`BACKGROUND
`
`FIG. 1 showsa part of a telecommunication network 10.
`The radio access network 10 comprises a plurality of radio
`base stations 11 (whereof only one is shown in the figure),
`each of which communicates with a plurality of UEs (user
`equipments) 12 located in the coverage area of the radio base
`station. The base station 11 further communicates with a
`
`core network 13. For example, where the network 10 is a
`standardized E-UTRAN (Evolved UMTSTerrestrial Radio
`Access Network), the core network 13 comprises an evolved
`packet core, itself comprising a mobility managemententity
`(MMB), a serving gateway and a PDN(packet data network)
`gateway.
`The E-UTRANcurrently supports bandwidths up to 20
`MHz. However, one of the requirements offuture releases of
`this standard such as LTE Advanced is the support of
`bandwidths larger than 20 MHz. A further important future
`requirement is to assure backward compatibility with pre-
`vious releases. This also includes spectrum compatibility.
`That implies that a future-release carrier, wider than 20
`MHz, appears as a numberofcarriers to a legacy UE. Each
`such carrier can be referred to as a componentcarrier. In
`particular for early deployments of future releases, it can be
`expected that there will be a smaller number of future-
`release UEs compared to many legacy UEs. Therefore, it is
`necessary to assure an efficient use of a wide carrier also for
`legacy UEs,
`i.e. that it is possible to implement carriers
`where legacy UEs can be scheduled in all parts of the
`wideband future-release carrier. The straightforward way to
`obtain this is by means of carrier aggregation. Carrier
`aggregation implies that a future-release UE can receive
`multiple component carriers, where the componentcarriers
`have, or at least have the possibility of having, the same
`structure as a carrier of previousreleases.
`Different examples of carrier aggregationare illustrated in
`FIGS. 2a to 2c. A contiguousintra-band carrier aggregation
`is illustrated in FIG. 2a where five componentcarriers 20,
`each of 20 MHz bandwidth, have been aggregated to form
`a bandwidth of 100 MHz. FIG.26illustrates a non-contigu-
`ous intra-band carrier aggregation where three component
`carriers 20, each of 20 MHz bandwidth, have been aggre-
`gated together to form an aggregated bandwidth of 60 MHz.
`Finally, FIG. 2c illustrates a inter-band carrier aggregation
`where two component carriers 20 in band x and band y
`respectively, each of 20 MHz bandwidth, have been aggre-
`gated together to form an aggregated bandwidth of 40 MHz.
`
`2
`The numberof aggregated componentcarriers as well as
`the bandwidth of the individual component carrier may be
`different for uplink (UL) and downlink (DL). A symmetric
`configuration refers to the case where the number of com-
`ponent carriers in DL and UL is the same whereas an
`asymmetric configuration refers to the case that the number
`of componentcarriers is different. It should be noted that the
`number of component carriers configured in a network
`might be different from the number of componentcarriers
`seen by a UE. A UE may for example support more DL
`component carriers than UL component carriers, even
`though the network is configured with the same numberof
`UL and DL componentcarriers.
`The current E-UTRAN but also LTE Advanced uses
`
`DFTS-OFDM (Discrete Fourier Transform Spread-Or-
`thogonal Frequency Division Multiplex) for modulation in
`the UL. DFTS-OFDM isa special kind of FDM (Frequency
`Division Multiplex) where different users are assigned dif-
`ferent portions of the spectrum. Orthogonality among dif-
`ferent users relies on the time-aligned arrival of the UL
`signals of the various users. In current E-UTRAN and LTE
`Advanceda cyclic prefix is used which relaxes the require-
`ment on timing alignmentslightly. Hence, it is sufficientif
`the signals are aligned within a fraction of the cyclic prefix.
`The normal cyclic prefix in LTE is around 5 us; signals from
`different users should then be aligned within 1 Ls or so.
`UEs synchronize their DL timings to DL signals trans-
`mitted from an eNodeB,
`i.e. a radio base station of an
`E-UTRAN.Signals used for this purpose comprise synchro-
`nization signals and reference signals. After established
`downlink synchronization a UE canstart to transmit signals
`in the UL from the UEto the eNodeBat a well-definedoffset
`relative to the DL timing. However, due to varying UE-
`eNodeB distances among UEs the synchronization signals
`arrive at different time instances at the UEs creating UE
`specific DL timings at each UE. This results in different
`transmission instances among the UEs. UEs close to the
`eNodeB receive the synchronization signal early and thus
`also start
`to transmit early;
`their respective UL signals
`require furthermore only a short propagation timeto arrive
`at the eNodeB. UEs far away from the eNodeB start to
`transmit later and their UL signals require also more time to
`traverse the distance to the eNodeBresulting in later signal
`arrival times at the eNodeB. The time difference between
`arriving signals from two UEsis the difference in roundtrip
`time between these two UEs. Roundtrip time is defined as
`the time duration that is needed for a signal to traverse the
`distance eNodeB-UE and back (assuming zero processing
`delay at the UE) and is calculated as twice the distance
`eNodeB-UEdivided by the speed of light.
`In order to align the arrival times of UL signals from
`different UEs the eNodeB measuresthe arrival times of the
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`different signals relative to a desired arrival time reference
`and informs the UEs by how much they have to advance/
`delay their UL transmission timings(eitherrelative to their
`UEspecific DL timings or to the current UL transmission
`timing). This process is called timing alignment procedure
`and the command usedto notify the UE about the required
`correction is called timing advance command.
`In case of a UE with completely unsynchronized UL
`timing the UE does not transmit a regular UL signal but a
`random accesssignal. This signalis specifically designed for
`unsynchronized UEs. After the eNodeB has determined the
`required correction of UL transmit timing it transmits a
`corresponding timing advance command to the UE, which
`corrects its UL timing accordingly. After that the UE can
`now start to transmit regular UL signals, which assume
`10
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`US 10,285,150 B2
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`3
`alignedarrival timings. The eNodeB continuously monitors
`ULsignal arrival timings and sends timing advance com-
`mands to maintain a valid UL timing. If a UE is not active
`in the UL for a long time or looses UL synchronization for
`another reason a new random access needs to be performed
`to establish a valid UL timing again.
`In case of UL carrier aggregation all UL signals within a
`component carrier and/or across contiguous componentcar-
`riers need to be timing aligned in order to maintain orthogo-
`nality.
`
`SUMMARY
`
`5
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`4
`According to a fourth aspect of the present invention, a
`user equipment for determining an uplink transmission
`timing correction for communication in a telecommunica-
`tion system is provided. Aggregation of componentcarriers
`is applied in the telecommunication system. The user equip-
`ment comprises a transmitter for sending a signal on an
`uplink component carrier to a base station. Moreover, the
`user equipment includes a receiver for receiving a timing
`correction of the uplink transmission timing and information
`on which uplink componentcarrier the timing correction is
`valid for from the base station. Additionally, a unit for
`adjusting the uplink transmission timing of the component
`carrier the timing correction is valid for based on the timing
`It is therefore an object of the present invention to provide
`correction is comprised in the user equipment.
`a solution for transmission timing alignment in a telecom-
`An advantage of embodiments of the present invention is
`munication system in which aggregation of component
`that
`they provide a possibility to use only one timing
`carriers is applied.
`correction for all componentcarriers, e.g. a single UL timing
`The above stated object is achieved by means of methods
`advance command, when possible and reverts back to a
`and arrangements according to the independent claims, and
`timing correction for each componentcarrier, e.g. multiple
`by the embodiments according to the dependent claims.
`ULtiming advance commands, only if required.
`According to a first aspect of the present invention, a
`Another advantage of embodiments of the present inven-
`method in a base station (600) for determining an uplink
`tion is that they reduce the signal overhead in the telecom-
`transmission timing correction for communication inatele-
`munication system.
`25
`communication system is provided. Aggregation of compo-
`Yet another advantage of embodiments of the present
`nent carriers is applied in the telecommunication system.
`invention is that the complexity of the processing of the user
`The method comprising receiving a signal on a selected
`equipmentis reduced when a single timing correction, e.g.
`uplink componentcarrier from a user equipment. An arrival
`one common timing advance command, is used for several
`time of the received signal is measured and a timing cor-
`component carriers.
`rection of the uplink transmission timing based on the
`Further advantages and features of embodiments of the
`measured arrival
`time is determined. Furthermore the
`present invention will become apparent when reading the
`following detailed description in conjunction with the draw-
`ings.
`
`method comprises the step of determining for which of the
`uplink componentcarriers used by the user equipment the
`determined timing correction is valid. Additionally,
`the
`method comprises the step of sending the timing correction
`and information on which of the uplink componentcarriers
`the timing correction is valid for to the user equipment.
`For a better understanding, reference is made to the
`According to a second aspect of the present invention, a
`following drawings and preferred embodiments of the
`invention.
`method in a user equipment for determining an uplink
`40
`transmission timing correction for communication inatele-
`FIG. 1 depicts schematically a telecommunication sys-
`communication system is provided. Aggregation of compo-
`tem, wherein embodiments of the present invention may be
`nent carriers is applied in the telecommunication system.
`implemented.
`The method comprises the step of sending a signal on an
`FIGS. 2a to 2c show different examples ofcarrier aggre-
`uplink componentcarrier to a base station. Furthermore, a
`gation.
`timing correction of the uplink transmission timing and
`FIG. 3 is a schematic block diagram illustrating an
`information on which uplink component carrier the timing
`embodimentof the present invention wherein the DL timing
`correction is valid for is received from the base station.
`references are related to each other.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`45
`
`Thereupon, the method in the user equipment adjusts the
`uplink transmission timing of the component carrier the
`timing correction is valid for based on the timing correction.
`According to a third aspect of the present invention, a
`base station for determining an uplink transmission timing
`correction for communication in a telecommunication sys-
`tem is provided. Aggregation of component carriers is
`applied in the telecommunication system. The base station
`comprises a receiver for receiving a signal on a selected
`uplink componentcarrier from a user equipment and a unit
`for measuring an arrival time of the received signal. The
`base station further includes a unit for determining a timing
`correction of the uplink transmission timing based on the
`measured arrival time and for determining for which of the
`uplink componentcarriers used by the user equipment the
`determined timing correction is valid. Additionally, a trans-
`mitter for sending the timing correction and information on
`which of the uplink component carriers the timing correction
`is valid for to the user equipment is comprised in the base
`station.
`
`FIG. 4 is a schematic block diagram illustrating an
`embodimentof the present invention wherein the DL timing
`references are not related to each other.
`
`50
`
`FIGS. 5a and 58 are flowcharts of the method according
`to an embodimentof the present invention performed in the
`base station and the user equipment, respectively.
`FIG. 6 is a schematic block diagram illustrating a base
`station according to an embodimentofthe present invention.
`FIG. 7 is a schematic block diagram illustrating a user
`equipment according to an embodiment of the present
`invention.
`
`DETAILED DESCRIPTION
`
`In the following description, for purposes of explanation
`and not limitation, specific details are set forth, such as
`particular sequencesofsteps, signaling protocols and device
`configurations in order to provide a thorough understanding
`of the present invention. It will be apparent to one skilled in
`the art that the present invention may be practiced in other
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`US 10,285,150 B2
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`6
`configured with a first DL component carrier 31 and a
`second DL componentcarrier 32 and a first UL component
`carrier 33 and a second componentcarrier 34. Both thefirst
`and the second UL componentcarrier 33, 34 derive their UL
`transmission timings from the first DL componentcarrier31.
`Thus, only one timing advance command TAis needed.
`Acommon DL timing reference could be for example the
`synchronization signal or the reference signals of one DL
`component carrier. Another example of a common DL
`timing reference could be synchronization signals on differ-
`ent componentcarriers if they are synchronized. DL timing
`references that are not the same but anyway share a well-
`defined relation with each other could be synchronization
`signals on DL componentcarriers where the transmit tim-
`ings are not the same but have a clearly defined offset
`relative to each other.
`
`10
`
`5
`embodiments that depart from these specific details. In the
`drawings, like reference signs refer to like elements.
`Moreover, those skilled in the art will appreciate that the
`means and functions explained herein below may be imple-
`mented using software functioning in conjunction with a
`programmed microprocessor or general-purpose computer,
`and/or using an application specific integrated circuit
`(ASIC). It will also be appreciated that while the current
`invention is primarily described in the form of methods and
`devices, the invention may also be embodied in a computer
`program product as well as a system comprising a computer
`processor and a memory coupled to the processor, wherein
`the memory is encoded with one or more programs that may
`perform the functions disclosed herein.
`The present
`invention is described herein by way of
`reference to particular example scenarios.
`In particular
`embodiments of the invention are described in a non-
`
`in relation to an E-UTRAN.It
`limiting general context
`should though be noted that the invention and its exemplary
`embodiments are applicable to other types of radio access
`networks in which aggregation of component carriers is
`applied.
`In a telecommunication system in which aggregation of
`UL component carriers is applied all UL signals within a
`component carrier and/or across contiguous componentcar-
`riers need to be timing aligned in order to maintain orthogo-
`nality.
`Thearrival time of two or more UL componentcarriers at
`the base station is influenced by the transmission timing of
`each respective UL carrier as well as the propagation delay
`experienced by each UL signal. Howeverin mostcases, the
`arrival time of the UL component carrier is mainly deter-
`mined by the transmission timing.
`According to the basic concept of the present invention,
`the base station receives a signal from a user equipment on
`an UL componentcarrier and measures the arrival time of
`the signal. A timing correction of the UL transmission timing
`based on the arrival
`time of the signal
`is determined.
`Thereupon the base station determines for which of the
`uplink componentcarriers used by the user equipment the
`timing correction is valid. The timing correction and the
`validity information are sent to the user equipment. The user
`equipment adjusts the UL transmission timing for each UL
`componentcarrier the timing correction is valid for.
`A message carrying the information for which UL com-
`ponentcarrier the timing correction is valid can either be an
`independent message or it can be sent together with the
`timing correction. An independent signaling of validity
`information can for example be signaled via RRC (Radio
`Resource Control) signaling or MAC (Media Access Con-
`trol) control elements. A combined message carrying both
`timing correction and validity information is typically sig-
`naled as MAC control element but other signaling schemes
`are possible as well. In one embodiment of the present
`invention the timing correction is sent in a timing advance
`command to the user equipment.
`invention the UL
`In one embodiment of the present
`componentcarriers used by a user equipmentare associated
`with a common DL timing reference—andthus should have
`the same UL transmit timing—and should have the same UL
`receive timing, one timing advance commandis sufficient
`for all UL componentcarriers used by the user equipment.
`The samealso appliesif they use different—but well defined
`with respect to each other—DL timing references. The UL
`transmit timings and thus also the UL receive timings will
`have the samerelationship to each other as the DL timing
`references. FIG. 3 shows a user equipment 30 which is
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`In another embodiment of the present invention the DL
`timing referencesare not related to each other. FIG. 4 shows
`a user equipment 40, which is configured with a first DL
`component carrier 41, a second DL component carrier 42
`and a third DL componentcarrier 43. It is further configured
`with a first UL componentcarrier 44 and a second compo-
`nent carrier 45. The DL timing reference of the first DL
`component carrier 41 is not related to the DL timing
`reference of the third DL componentcarrier 43. In order to
`guarantee clearly defined UL receive timings for both UL
`component carriers,
`individual UL timing advance com-
`mands for each UL component carrier are required. Thus,
`the first UL componentcarrier 44 derives its UL transmis-
`sion timing from the first DL component carrier 41 and the
`second UL componentcarrier 45 derives its UL transmission
`timing from the third DL componentcarrier 43. Thus, the
`user equipment receives a first timing advance command
`TA, and a second timing advance command TA,.
`An example where an UL timing advance command for
`each UL componentcarrier should be usedis in a case with
`aggregation of multiple time-division duplex (TDD) com-
`ponent carriers with different DL and ULallocations across
`them. Since TDD DL transmitters are typically timing
`aligned with neighboring TDD DLtransmitters to mitigate
`interference it is necessary that each of the TDD component
`carriers can set their DL timing references individually. Due
`to possible different DL and UL allocations, individual UL
`receive timings are required which makes individual UL
`timing advance commands necessary.
`In the following the above embodiments will be further
`explained with reference to FIGS. 5a-6, 6 and 7.
`FIG.5a is a flowchart of a methodin a base station (BS)
`for determining an uplink transmission timing correction for
`communication in a telecommunication system of the pres-
`ent invention. Aggregation of componentcarriers is applied
`in the telecommunication system. In a step 50, the base
`station receives a signal on a selected uplink component
`carrier of several aggregated componentcarriers from a user
`equipment. Next, the base station measures an arrival time
`of the received signal in a step 51. Thereupon, in a step 52,
`the base station determines a timing correction of the uplink
`transmission, i.e. the timing correction that is to be applied
`on the uplink transmissions from the UE, based on the
`measured arrival time. In next step 53, the validity of the
`timing correction is determined. Thatis, it is determined for
`which of the uplink component carriers used by the user
`equipmentthe determined timing correction is valid. In one
`embodiment the mentioned determination is based on a
`downlink timing reference associated with the respective
`uplink component carrier used by the user equipment.
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`US 10,285,150 B2
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`8
`timing correction. An independent signaling of the informa-
`tion on which componentcarrier the timing correction is
`valid for could be done with RRC signaling or with MAC
`control elements. A combined message carrying both timing
`correction and validity information is typically received as
`MACcontrol element but other signaling schemes are
`possible as well. In one embodimentthe timing correction is
`received by the user equipment in a timing advance com-
`mand.
`
`In another embodiment when the componentcarriers are
`time division duplex carriers with different downlink or
`uplink allocations across the carriers, the timing correction
`is determined to be valid for only the selected component
`carrier.
`
`7
`In a step 54, the timing correction and the information on
`which of the uplink component carriers the timing correction
`is valid for are sent to the user equipment. This could be
`executed in different ways. A message carrying the infor-
`mation for which UL componentcarrier the timing correc-
`tion is valid can either be an independent messageorit can
`be sent together with the timing correction. An independent
`signaling of the information on which componentcarrier the
`timing correction is valid for could be done with RRC
`signaling or with MAC control elements. A combined mes-
`sage carrying both timing correction and validity informa-
`tion is typically signaled as MAC control element but other
`signaling schemesare possible as well. In one embodiment
`of the present invention the timing correction is sent in a
`timing advance commandto the user equipment.
`In one embodiment, the timing correction could be deter-
`mined to be valid for the uplink componentcarrier of the
`aggregated component carriers which has an associated
`downlink timing reference aligned with the downlink timing
`reference associated with the selected uplink component
`carrier. In such a case the downlink timing reference could
`be a synchronization signal or reference signal of one of the
`downlink componentcarrier used by the user equipment.
`In another embodiment were the downlink timing refer-
`ence associated with a componentcarrieris not the same but
`has a well-defined relation with the downlink timing refer-
`ence associated with the selected component carrier,
`the
`timing correction could be determined to be valid for said
`uplink componentcarrier. That is, the timing correction is
`determined to be valid for all uplink component carriers
`which have an associated downlink timing reference with a
`defined offset relative to the downlink timing reference
`associated with the selected uplink component carrier on
`whichthe signal is received from the user equipment in step
`50. In this case, the downlink timing references could be
`synchronization signals or reference signals on different
`downlink componentcarriers.
`Tt should be pointed out that the validity information,i.e.
`the validity of the timing correction, is in one embodiment
`of the present invention determined during setup of the base
`station and sent to the UE when an UL componentcarrier is
`added. Thus, the validity information could be sent to the UE
`before the timing correction is sent to the UE andalso less
`frequent than the timing correction.
`In an exemplary embodimentofthe present invention the
`base station measuresthe arrival time of the signal received
`from the UEandrelates the measuredtimeto an arrival time
`reference. The arrival time reference could be the arrival
`time that the base station desires to receive a signal from the
`UE. Thus, the timing correction determined by the base
`station could be based on the measured arrival time of the
`received signal and the arrival time reference.
`FIG.56 is a flowchart of a method in a user equipmentfor
`determining an uplink transmission timing correction for
`communication in a telecommunication system of the pres-
`ent invention. Aggregation of componentcarriers is applied
`in the telecommunication system. In a step 55, the user
`Whatis claimedis:
`equipment sends a signal on a selected uplink component
`1. A method in a base station for determining an uplink
`carrier of several aggregated componentcarriers to the base
`60
`
`station. Thereupon, the user equipment receives from the transmission timing correction for communication inatele-
`base station a timing correction of the uplink transmission
`communication system in which aggregation of component
`timing and information on which uplink componentcarrier
`carriers is applied, the method comprising:
`the timing correction is valid for in a step 56. As mention
`receiving a signal on a selected uplink componentcarrier
`previously, this step could be executed in different ways. A
`from a user equipment;
`message carrying the information for which UL component
`measuring an arrival time of the received signal;
`carrier the timing correction is valid can either be an
`determining a timing correction ofthe uplink transmission
`independent messageorit can be received together with the
`timing based on the measured arrival time;
`
`Schematically illustrated in FIG. 6 and according to
`embodiments described above, the base station 600 com-
`prises a receiver 620 for receiving a signal on a selected
`uplink componentcarrier from a user equipment and a unit
`for measuring 630 an arrival time of the received signal. It
`further comprises at least one unit for determining 640 a
`timing correction of the uplink transmission timing based on
`the measured arrival time and for determining for which of
`the uplink component carriers used by the user equipment
`the determined timing correction is valid. Finally, a trans-
`mitter 650 is comprised in the base station for sending the
`timing correction and information on which of the uplink
`componentcarriers the timing correction is valid for to the
`user equipment.
`Schematically illustrated in FIG. 7 and according to
`embodiments described above,
`the user equipment 700
`comprises a transmitter 720 for sending a signal on a
`selected uplink component carrier to a base station and a
`receiver 730 for receiving a timing correction of the uplink
`transmission timing and information on which uplink com-
`ponentcarrierthe timing correction is valid for from the base
`station. It further includes a unit for adjusting 740 the uplink
`transmission timing of the component carrier the timing
`correction is valid for based on the timing correction.
`It should be noted that the units illustrated in FIGS. 6 and
`7, respectively, could be implementedas a single unit or be
`divided into several units. The units may be implemented as
`physical or logical entities, such as by processing circuits
`610, 710. In general, such units comprise processing cir-
`cuitry, such as may be implemen