a2) United States Patent
`US 8,634,313 B2
`(0) Patent No.:
`Jan. 21, 2014
`(45) Date of Patent:
`Tennyetal.
`
`US008634313B2
`
`METHOD AND APPARATUS THAT
`FACILITATES A TIMING ALIGNMENT IN A
`MULTICARRIER SYSTEM
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`(54)
`
`(75)
`
`Inventors: Nathan Edward Tenny, Poway, CA
`(US); Parag Arun Agashe, San Diego,
`CA (US); Peter Gaal, San Diego, CA
`(US); Tingfang Ji, San Diego, CA (US);
`Ravi Palanki, San Diego, CA (US);
`Rajat Prakash, La Jolla, CA (US)
`
`(73)
`
`Assignee: QUALCOMMIncorporated, San
`Diego, CA (US)
`
`(*)
`
`Notice:
`
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 825 days.
`
`(21)
`
`Appl. No.: 12/818,064
`
`(22)
`
`Filed:
`
`Jun. 17, 2010
`
`(65)
`
`(60)
`
`(51)
`
`(52)
`
`(58)
`
`Prior Publication Data
`
`US 2011/0158116 Al
`
`Jun. 30, 2011
`
`Related U.S. Application Data
`
`Provisional application No. 61/218,769, filed on Jun.
`19, 2009, provisional application No. 61/294,053,
`filed on Jan. 11, 2010, provisional application No.
`61/305,014, filed on Feb. 16, 2010.
`
`Int. Cl.
`
`(2009.01)
`
`HOAW 56/00
`U.S. Cl.
`USPC. one 370/252; 370/336; 370/350; 370/503
`Field of Classification Search
`USPC. oo... 370/252, 329-338, 345, 347, 350, 503;
`709/230; 455/450
`See application file for complete search history.
`
`11/1994 Chuangetal.
`5,363,375 A
`6,321,083 B1* 11/2001 Vaaraetal. oe. 455/446
`
`(Continued)
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`EP
`
`1887758 A2
`1988648 Al
`
`2/2008
`11/2008
`
`(Continued)
`OTHER PUBLICATIONS
`
`E-Mail Rapporteur (NTT Docomoet al: “CA , support for multi-TA”
`3GPP Draft; R2-101567, 3rd Generation Partnership Project (3GPP),
`Mobile Competence Centre ; 650, Route Des Lucioles ; F-06921
`Sophia-Antipolis Cedex ; France, vol. RAN WG2,no. San Francisco,
`USA; 20100222, Feb. 18, 2010, XP05042 1923 [retrieved on Feb. 18,
`2010] paragraphs [000 1]-[02.2].
`
`(Continued)
`
`Primary Examiner — Michael Thier
`Assistant Examiner — Vincelas Louis
`
`(74) Attorney, Agent, or Firm — Nerrie M. Zohn
`
`ABSTRACT
`(57)
`Aspects are disclosed for facilitating a timing alignment in a
`multicarrier system. In one aspect, at least one downlink
`timing associated with at least one downlink carrier is deter-
`mined, and an uplink timing associated with an uplink group
`of carriers is ascertained based on at least one downlink
`timing and a timing offset associated with the uplink group of
`carriers. Each ofthe uplink groupofcarriers is then transmit-
`ted within a threshold value of the uplink timing. In another
`aspect, a downlink communication is transmitted to a wire-
`less terminal via at least one downlink carrier. This embodi-
`ment further includes assigning a timing offset to an uplink
`groupof carriers, and providing the timing offset to the wire-
`less terminal via the at least one downlink carrier. An uplink
`communication is then received via the uplink group of car-
`riers according to the timing offset.
`
`88 Claims, 14 Drawing Sheets
`
`Downlink
`
`412
`
`
`Downlink
`
`—~ 422
`
`
`
`Carrier
`
`410
`
`Carrier
`420
`
`Nie
`
`Uplink
`A14
`
`424
`
`—Uplink
`
`at
`
`inter-Carrier Offset <
`Timing Group Tolerance
`
`
`Signaled Downlink/Uplink Offset
`
`APPLE 1008
`
`1
`
`APPLE 1008
`
`

`

`US 8,634,313 B2
`Page 2
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`6,363,375
`6,545,996
`6,633,559
`6,839,333
`6,967,936
`7,254,118
`7,688,785
`8,400,935
`2004/0266445
`2006/02747 12
`2006/0280142
`2008/0037487
`2009/0228598
`2009/03 18175
`2010/0142457
`2011/0075629
`2011/0235620
`2011/0286411
`2011/0319116
`2012/0002617
`2012/0120821
`
`BI*
`BI*
`BI*
`BI*
`BI*
`BI*
`B2*
`B2*
`Al*
`Al*
`Al*
`Al*
`Al*
`Al*
`Al*
`Al*
`Al*
`Al*
`Al*
`Al*
`Al*
`
`3/2002
`4/2003
`10/2003
`1/2005
`11/2005
`8/2007
`3/2010
`3/2013
`12/2004
`12/2006
`12/2006
`2/2008
`9/2009
`12/2009
`6/2010
`3/2011
`9/2011
`11/2011
`12/2011
`1/2012
`5/2012
`
`Hoshinoet al. occ cece V1
`Falco etal.
`....
`. 370/347
`
`Asokan etal. occ 370/350
`Akerberg occ 370/330
`Laroia et al.
`...
`. 370/329
`
`..
`Terasawaet al.
`. 370/328
`Bachmannetal.
`. 370/331
`
`.
`Pelletier et al.
`. 370/252
`
`Burgessetal.
`. 455/450
`.....
`Malladi et al.
`. 370/345
`Damnjanovicet al.
`....... 370/329
`Li etal. once 370/338
`Stamouliset al.
`. 709/230
`
`Sandberg wc 455/502
`Chunet al. we 370/329
`Seo etal.
`....
`. 370/330
`Ahnet al.
`. 370/336
`...
`Kim et al.
`. 370/329
`Iwamuraet al.
`. 455/517
`Wujeic we
`. 370/329
`Kazmi etal. oo 370/252
`
`
`
`
`FOREIGN PATENT DOCUMENTS
`
`JP
`JP
`WO
`
`2009124450 A
`2009219625 A
`2009022840 A2
`
`6/2009
`10/2009
`2/2009
`
`OTHER PUBLICATIONS
`Ericssonet al: “Multiple Timing Advance , for Carrier Aggregation”
`3GPP Draft; R2-101196—Multiple TA for CA, 3rd Generation Part-
`nership Project (3GPP), Mobile Competence Centre ; 650, Route Des
`Lucioles ; F-06921 Sophia-Antipolis Cedex ; France, vol. RAN
`WG2, no. San Francisco, USA; 20100222, Feb.
`16, 2010,
`XP050421769 [retrieved on Feb. 16, 2010] paragraphs [0001]-[02.
`2].
`Ericsson: “Reference for Timing Advance” 3GPP Draft; R2-103106
`Reference for Timnig Advance, 3rd Generation Partnership Project
`(3GPP), Mobile Competence Centre ; 650, Route Des Lucioles ;
`F-06921 Sophia-Antipolis Cedex ; France, vol. RAN WG2, no.
`Montreal, Canada; 20100510, May 3, 2010, XP050423092[retrieved.
`on May 3, 2010] paragraphs [0001]-[0003].
`International Search Report and Written Opinion—PCT/U $2010/
`039372, International Search Authority—European Patent Office—
`Oct. 4, 2010.
`RAN2?: “LS on RAN2status on carrier aggregation design” 3GPP
`Draft; R2-093599, 3rd Generation Partnership Project (3GPP),
`Mobile Competence Centre ; 650, Route Des Lucioles ; F-06921
`Sophia-Antipolis Cedex ; France, no. San Francisco, USA;
`20090509, May 9, 2009, XP05034 1057 [retrieved on May 9, 2009]
`paragraph [0001].
`Ericsson, “Impact of Carrier Aggregation on the L2 protocol archi-
`tecture for LTE Rel-10”, 3GPP TSG-RAN WG2 #66, TDOC
`R2-092957, San Francisco, USA, May 4-8, 2009, pp.
`1-8,
`URL,http://www.3 gpp.org/ftp/tsg_ran/WG2_RL2/TSGR2_66/
`docs/R2-092957.zip.
`Taiwan Search Report—TW099120 129—TIPO—May27, 2013.
`
`* cited by examiner
`
`2
`
`

`

`U.S. Patent
`
`Jan. 21, 2014
`
`Sheet 1 of 14
`
`US 8,634,313 B2
`
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`

`

`U.S. Patent
`
`Jan. 21, 2014
`
`Sheet 2 of 14
`
`US 8,634,313 B2
`
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`U.S. Patent
`
`Jan. 21, 2014
`
`Sheet 3 of 14
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`US 8,634,313 B2
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`U.S. Patent
`
`Jan. 21, 2014
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`Sheet 4 of 14
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`US 8,634,313 B2
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`U.S. Patent
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`Jan. 21, 2014
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`Sheet 5 of 14
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`U.S. Patent
`
`Jan. 21, 2014
`
`Sheet 6 of 14
`
`US 8,634,313 B2
`
`FIG.6
`
`600
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`WIRELESS TERMINAL
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`610
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`MEMORY
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`620
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`
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`
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`COMPONENT
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`630
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`UPLINK TIMING
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`COMPONENT
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`640
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`COMMUNICATION
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`
`

`

`U.S. Patent
`
`Jan. 21, 2014
`
`Sheet 7 of 14
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`US 8,634,313 B2
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`U.S. Patent
`
`Jan. 21, 2014
`
`Sheet 8 of 14
`
`US 8,634,313 B2
`
`FIG. 8
`
`DETERMINE
`DOWNLINK
`TIMING
`
`ASCERTAIN
`TIMING OFFSET
`
`RECEIVE
`DOWNLINK
`COMMUNICATION
`
`COMMUNICATION
`
`ASSOCIATE UPLINK
`GROUP WITH
`DOWNLINK GROUP
`
`ASCERTAIN
`UPLINK TIMING
`OF GROUP
`
`TRANSMIT UPLINK
`
`10
`
`10
`
`

`

`U.S. Patent
`
`Jan. 21, 2014
`
`Sheet 9 of 14
`
`US 8,634,313 B2
`
`BASE STATION
`
`PROCESSOR
`
`COMPONENT
`
`910
`
`FIG. 9
`
`
`
`970
`
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`COMPONENT
`920
`
`TIMING OFFSET
`COMPONENT
`930
`
`RANSMITTING
`
`COMPONENT
`
`940
`
`RECEIVING
`
`COMPONENT
`
`950
`
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`COMPONENT
`960
`
`RANDOM ACCESS
`COMPONENT
`
`11
`
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`
`

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`U.S. Patent
`
`Jan. 21, 2014
`
`Sheet 10 of 14
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`US 8,634,313 B2
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`U.S. Patent
`
`Jan. 21, 2014
`
`Sheet 11 of 14
`
`US8,634,313 B2
`
`FIG.11
`
`ESTABLISH
`COMMUNICATION WITH
`
`USER EQUIPMENT
`
`ASSIGN TIMING
`
`OFFSET
`
`COMMUNICATION
`
`CONFIGURE
`
`DOWNLINK
`
`CARRIERS
`
`PROVIDE TIMING
`OFFSET TO USER
`
`EQUIPMENT
`
`RECEIVE UPLINK
`
`13
`
`13
`
`

`

`U.S. Patent
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`Jan. 21, 2014
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`Sheet 12 of 14
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`US 8,634,313 B2
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`U.S. Patent
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`Jan. 21, 2014
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`Sheet 13 of 14
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`Jan. 21, 2014
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`

`US 8,634,313 B2
`
`1
`METHOD AND APPARATUS THAT
`FACILITATES A TIMING ALIGNMENT IN A
`MULTICARRIER SYSTEM
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`This application claims the benefit of U.S. Provisional
`Patent Application Ser. No. 61/218,769 entitled “TIMING
`ALIGNMENT IN A MULTICARRIER SYSTEM,” which
`wasfiled Jun. 19, 2009, U.S. Provisional Patent Application
`Ser. No. 61/294,053 entitled “TIMING ALIGNMENT IN A
`MULTICARRIER SYSTEM,”whichwasfiled Jan. 11, 2010,
`and U.S. Provisional Patent Application Ser. No. 61/305,014
`entitled “TIMING ALIGNMENT IN A MULTICARRIER
`
`SYSTEM,” which wasfiled Feb. 16, 2009. The aforemen-
`tioned applications are herein incorporated by reference in
`their entirety.
`
`BACKGROUND
`
`I. Field
`
`The following description relates generally to wireless
`communications, and moreparticularly to methods and appa-
`ratuses that facilitate maintaining timing synchronization for
`user equipment in a multicarrier Long Term Evolution-Ad-
`vanced (LTE-A) system.
`II. Background
`Wireless communication systems are widely deployed to
`provide various types of communication content such as
`voice, data, and so on. These systems may be multiple-access
`systems capable of supporting communication with multiple
`users by sharing the available system resources(e.g., band-
`width and transmit power). Examples of such multiple-access
`systemsinclude code division multiple access (CDMA) sys-
`tems, time division multiple access (TDMA) systems, fre-
`quency division multiple access (FDMA) systems, 3GPP
`Long Term Evolution (LTE) systems, and orthogonalfre-
`quency division multiple access (OFDMA)systems.
`Generally, a wireless multiple-access communication sys-
`tem can simultaneously support communication for multiple
`wireless terminals. Each terminal communicates with one or
`more base stations via transmissions on the forward and
`reverse links. The forward link (or downlink) refers to the
`communication link from the base stations to the terminals,
`and the reverse link (or uplink) refers to the communication
`link from the terminals to the base stations. This communi-
`cation link may be established via a single-in-single-out,
`multiple-in-signal-out or a multiple-in-multiple-out (MIMO)
`system.
`AMIMOsystem employs multiple (N) transmit antennas
`and multiple (N,) receive antennas for data transmission. A
`MIMOchannel formed by the N, transmit and Nz receive
`antennas may be decomposedinto Nx independent channels,
`which are also referred to as spatial channels, where
`N,smin{N,, Nz}. Each of the N, independent channelscor-
`responds to a dimension. The MIMO system can provide
`improved performance (e.g., higher
`throughput and/or
`greaterreliability) if the additional dimensionalities created
`by the multiple transmit and receive antennasare utilized.
`A MIMOsystem supports a time division duplex (TDD)
`and frequency division duplex (FDD) systems. In a TDD
`system, the forward andreverse link transmissions are on the
`same frequencyregionso that the reciprocity principle allows
`the estimation of the forward link channel from the reverse
`
`link channel. This enables the access point to extract transmit
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`beamforming gain on the forward link when multiple anten-
`nas are availableat the access point.
`With respect to timing synchronization in a single-carrier
`environment, it is noted that the maintenance of such timing
`synchronization for user equipment (UE) includes having the
`UE receive an uplink/downlink offset from the network,
`which occasionally needs to be updated, indicating how it
`should align its uplink transmissions in relation to the
`received downlink timing. In a multicarrier environment,
`however, the synchronization is more complex. Assuming
`thatall carriers serving a single UE are transmitted from the
`same cell site, it appears that a commonoffset should be
`adequate. However, even co-sited carriers could experience
`somevariation in timing for a numberofreasons(e.g., cable
`delays, distance between the base station site and a remote
`radio head, etc.), which would makeseparate timing offsets
`per carrier beneficial or even necessary.
`The above-described deficiencies of current wireless com-
`
`munication systems are merely intended to provide an over-
`view of someof the problems of conventional systems, and
`are not intended to be exhaustive. Other problems with con-
`ventional systems and corresponding benefits of the various
`non-limiting embodiments described herein may becomefur-
`ther apparent uponreview ofthe following description.
`
`SUMMARY
`
`The following presents a simplified summary of one or
`more embodimentsin order to provide a basic understanding
`of such embodiments. This summary is not an extensive over-
`view of all contemplated embodiments, and is intended to
`neither identify key or critical elements of all embodiments
`nor delineate the scope of any or all embodiments. Its sole
`purposeis to present some concepts of one or more embodi-
`ments in a simplified form as a prelude to the more detailed
`description that is presentedlater.
`In accordance with one or more embodiments and corre-
`
`sponding disclosure thereof, various aspects are described in
`connection with maintaining timing synchronization for user
`equipment in a LTE-A system. In one aspect, methods and
`computer program products are disclosed that facilitate a
`timing alignment in a multicarrier system. These embodi-
`ments include determiningat least one downlink timing asso-
`ciated with at least one downlink carrier, and ascertaining an
`uplink timing associated with an uplink group ofcarriers. For
`these embodiments, the uplink timing is ascertained based on
`a processing of at least one downlink timing and a timing
`offset associated with the uplink group of carriers. Each ofthe
`uplink group of carriers is then transmitted within a threshold
`value of the uplink timing.
`In another aspect, an apparatus configured to facilitate a
`timing alignment in a multicarrier system is disclosed. Within
`such embodiment, the apparatus includes a processor config-
`ured to execute computer executable components stored in
`memory. The computer executable components include a
`downlink timing component, an uplink timing component,
`and a communication component. The downlink timing com-
`ponent is configured to determineat least one downlink tim-
`ing associated with at least one downlink carrier, whereas the
`uplink timing componentis configured to ascertain an uplink
`timing associated with an uplink group of carriers. For this
`embodiment, the uplink timingis ascertained based on atleast
`one downlink timing and a timing offset associated with the
`uplink group of carriers. The communication componentis
`then configured to transmit each of the uplink group of car-
`riers within a threshold value of the uplink timing.
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`US 8,634,313 B2
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`3
`In a further aspect, another apparatus is disclosed. Within
`such embodiment, the apparatus includes means for deter-
`mining, meansfor ascertaining, and meansfor transmitting.
`For this embodiment, the means for determining determines
`at least one downlink timing associated with at least one
`downlink carrier, whereas the means for ascertaining ascer-
`tains an uplink timing associated with an uplink group of
`carriers. For this embodiment, the uplink timing is ascer-
`tained based on at least one downlink timing and a timing
`offset associated with the uplink group of carriers. The means
`for transmitting then transmits each of the uplink group of
`carriers within a threshold valueofthe uplink timing. In other
`embodiments, the apparatus further includes a means for
`performing a random access procedure onat least one random
`access carrier. For this embodiment, the at least one random
`accesscarrier is included in a downlink groupofcarriers that
`includesthe at least one downlink carrier.
`
`In another aspect, other methods and computer program
`products are disclosedfor facilitating a timing alignmentin a
`multicarrier system. For these embodiments, various acts are
`provided, including an act to transmit a downlink communi-
`cation to a wireless terminal via at least one downlink carrier.
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`These embodiments further include assigning a timing offset
`to an uplink groupof carriers, and providing the timing offset
`to the wireless terminalvia the at least one downlink carrier.
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`An uplink communication is then received via the uplink
`group of carriers according to the timing offset.
`Anotherapparatus for facilitating a timing alignment in a
`multicarrier system is also disclosed. Within such embodi-
`ment,
`the apparatus includes a processor configured to
`execute computer executable components stored in memory.
`The computer executable componentsinclude a timing offset
`component, a transmitting component, and a receiving com-
`ponent. The timing offset componentis configured to assign
`a timing offset to an uplink group of carriers, whereas the
`transmitting component is configured to provide the timing
`offset to a wireless terminal via at least one downlink carrier.
`
`The receiving component is then configured to receive an
`uplink communication via the uplink group of carriers
`according to the timing offset.
`In a further aspect, another apparatus is disclosed. Within
`such embodiment, the apparatus includes meansfor transmit-
`ting, meansfor assigning, meansfor providing, and meansfor
`receiving. For this embodiment, the means for transmitting
`transmits at least one downlink carrier to a wireless terminal.
`
`The means for assigning then assigns a timing offset to an
`uplink group of carriers, whereas the means for providing
`provides the timing offset to the wireless terminal via the at
`least one downlink carrier. The means for receiving then
`receives an uplink communication via the uplink group of
`carriers according to the timing offset. In another embodi-
`ment, the apparatus further includes a meansfor generating a
`timing message. For this embodiment, the timing message
`includes a set of uplink timing instructions which are pro-
`vided to the wireless terminal.
`
`To the accomplishmentof the foregoing and related ends,
`the one or more embodiments comprise the features herein-
`after fully described and particularly pointed out in the
`claims. The following description and the annexed drawings
`set forth in detail certain illustrative aspects ofthe one or more
`embodiments. These aspects are indicative, however,of but a
`few of the various ways in which the principles of various
`embodiments can be employed and the described embodi-
`ments are intended to include all such aspects and their
`equivalents.
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`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG.1 is an illustration of a wireless communication sys-
`tem in accordance with various aspects set forth herein.
`FIG.2 is anillustration of an exemplary wireless network
`environment that can be employed in conjunction with the
`various systems and methods described herein.
`FIG.3 is an illustration of an exemplary system where two
`timing groups are associated with a single eNodeB according
`to an embodiment.
`
`FIG.4 is an illustration of an exemplary ambiguous uplink
`timing.
`FIG. 5 is an illustration of an exemplary averaging of
`uplink timings according to an embodiment.
`FIG.6 illustrates a block diagram of an exemplary wireless
`terminal that facilitates a timing alignment in a multicarrier
`system in accordance with an aspectof the subject specitica-
`tion.
`FIG.7 is an illustration of an exemplary coupling ofelec-
`trical components that effectuate a timing alignment in a
`multicarrier system.
`FIG.8 is a flow chart illustrating an exemplary methodol-
`ogy for facilitating a timing alignmentin a multicarrier sys-
`tem in accordancewith an aspect of the subject specification.
`FIG.9 illustrates a block diagram of an exemplary base
`station that facilitates a timing alignment in a multicarrier
`system in accordance with an aspectof the subject specitica-
`tion.
`
`FIG. 10 is an illustration of an exemplary coupling of
`electrical componentsthat effectuate a timing alignmentin a
`multicarrier system.
`FIG. 11 is flow chart illustrating an exemplary methodol-
`ogy for facilitating a timing alignmentin a multicarrier sys-
`tem in accordancewith an aspect of the subject specification.
`FIG. 12 is an illustration of an exemplary communication
`system implemented in accordance with various aspects
`including multiple cells.
`FIG.13 is an illustration of an exemplary base station in
`accordance with various aspects described herein.
`FIG.14 is an illustration of an exemplary wireless terminal
`implemented in accordance with various aspects described
`herein.
`
`DETAILED DESCRIPTION
`
`Various embodiments are now described with reference to
`the drawings, wherein like reference numerals are used to
`refer to like elements throughout. In the following descrip-
`tion, for purposes of explanation, numerousspecific details
`are set forth in order to provide a thorough understanding of
`one or more embodiments. It may be evident, however, that
`such embodiment(s) may be practiced without these specific
`details. In other instances, well-knownstructures and devices
`are shownin block diagram form in orderto facilitate describ-
`ing one or more embodiments.
`The subject specification is directed towardsfacilitating a
`timing alignmentfor user equipment in systems with multiple
`carriers whose timing may be different. Exemplary embodi-
`ments are disclosed in which carriers are grouped into “tim-
`ing groups” with the similar timing information (within a
`tolerance), wherein signaling behavior for timing synchroni-
`zation takes place on a per-group basis rather than a per-
`carrier basis.
`
`To this end, it is noted that the techniques described herein
`can be usedfor various wireless communication systems such
`as code division multiple access (CDMA),time division mul-
`tiple access (TDMA), frequency division multiple access
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`US 8,634,313 B2
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`5
`(FDMA), orthogonal frequency division multiple access
`(OFDMA), single carrier-frequency division multiple access
`(SC-FDMA), High Speed Packet Access (HSPA), and other
`systems. The terms “system” and “network”are often used
`interchangeably. A CDMA system can implement a radio
`technology such as Universal Terrestrial Radio Access
`(UTRA), CDMA2000, etc. UTRA includes Wideband-
`CDMA (W-CDMA)
`and other variants of CDMA.
`CDMA2000 covers IS-2000, IS-95 and IS-856 standards. A
`TDMA system can implement a radio technology such as
`Global System for Mobile Communications (GSM). An
`OFDMA system can implementa radio technology such as
`Evolved UTRA (E-UTRA), Ultra Mobile Broadband
`(UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE
`802.20, Flash-OFDM,etc. UTRA and E-UTRA arepart of
`Universal Mobile Telecommunication System (UMTS).
`3GPP Long Term Evolution (LTE) is a release of UMTSthat
`uses E-UTRA, which employs OFDMA onthe downlink and
`SC-FDMA onthe uplink.
`Single carrier frequency division multiple access (SC-
`FDMA)utilizes single carrier modulation and frequency
`domain equalization. SC-FDMA has similar performance
`and essentially the same overall complexity as those of an
`OFDMA system. A SC-FDMA signal has lower peak-to-
`average power ratio (PAPR) because of its inherent single
`carrier structure. SC-FDMA can be used, for instance, in
`uplink communications where lower PAPRgreatly benefits
`access terminals in terms of transmit power efficiency.
`Accordingly, SC-FDMA can be implemented as an uplink
`multiple access scheme in 3GPP Long Term Evolution (LTE)
`or Evolved UTRA.
`
`High speed packet access (HSPA) can include high speed
`downlink packet access (HSDPA) technology and high speed
`uplink packet access (HSUPA) or enhanced uplink (EUL)
`technology and can also include HSPA+ technology. HSDPA,
`HSUPAand HSPA+arepart of the Third Generation Partner-
`ship Project (3GPP) specifications Release 5, Release 6, and
`Release 7, respectively.
`High speed downlink packet access (HSDPA) optimizes
`data transmission from the network to the user equipment
`(UE). As used herein, transmission from the network to the
`user equipment UEcanbereferred to as the “downlink” (DL).
`Transmission methodscan allow data rates of several Mbits/s.
`
`High speed downlink packet access (HSDPA)can increase
`the capacity of mobile radio networks. High speed uplink
`packet access (HSUPA) can optimize data transmission from
`the terminal to the network. As used herein, transmissions
`from the terminal to the network can be referred to as the
`“uplink” (UL). Uplink data transmission methods can allow
`data rates of several Mbit/s. HSPA+ provides even further
`improvements both in the uplink and downlink as specified in
`Release 7 of the 3GPP specification. High speed packet
`access (HSPA) methodstypically allow for faster interactions
`between the downlink and the uplink in data services trans-
`mitting large volumes of data, for instance Voice over IP
`(VoIP), videoconferencing and mobile office applications
`Fast data transmission protocols such as hybrid automatic
`repeat request, (HARQ) can be used on the uplink and down-
`link. Such protocols, such as hybrid automatic repeat request
`(HARQ), allow a recipient to automatically request retrans-
`mission of a packet that might have been received in error.
`Various embodiments are described herein in connection
`with an access terminal. An access terminalcan also be called
`
`a system, subscriber unit, subscriber station, mobile station,
`mobile, remote station, remote terminal, mobile device, user
`terminal,
`terminal, wireless communication device, user
`agent, user device, or user equipment (UE). An access termi-
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`nal can be acellular telephone, a cordless telephone, a Session
`Initiation Protocol (SIP) phone, a wireless local loop (WLL)
`station, a personal digital assistant (PDA), a handheld device
`having wireless connection capability, computing device, or
`other processing device connected to a wireless modem.
`Moreover, various embodiments are described herein in con-
`nection with a base station. A base station can beutilized for
`
`communicating with access terminal(s) and can also be
`referred to as an access point, Node B, Evolved Node B
`(eNodeB), access point base station, or some other terminol-
`ogy.
`Referring now to FIG. 1, a wireless communication system
`100 is illustrated in accordance with various embodiments
`
`presented herein. System 100 comprises a base station 102
`that can include multiple antenna groups. For example, one
`antenna group can include antennas 104 and 106, another
`group can comprise antennas 108 and 110, and an additional
`group can include antennas 112 and 114. Two antennas are
`illustrated for each antenna group; however, more or fewer
`antennas can be utilized for each group. Basestation 102 can
`additionally include a transmitter chain anda receiver chain,
`each ofwhich can in turn comprise a plurality of components
`associated with signal transmission and reception (e.g., pro-
`cessors, modulators, multiplexers, demodulators, demulti-
`plexers, antennas, etc.), as will be appreciated by oneskilled
`in the art.
`Base station 102 can communicate with one or more access
`terminals such as access terminal 116 and access terminal
`122; however, it is to be appreciated that basestation 102 can
`communicate with substantially any numberof access termi-
`nals similar to access terminals 116 and 122. Access terminals
`116 and 122 can be, for example, cellular phones, smart
`phones, laptops, handheld communication devices, handheld
`computing devices, satellite radios, global positioning sys-
`tems, PDAs, and/or any other suitable device for communi-
`cating over wireless communication system 100. As depicted,
`access terminal 116 is in communication with antennas 112
`and 114, where antennas 112 and 114 transmit information to
`access terminal 116 over a forward link 118 and receive
`information from access terminal 116 overa reverse link 120.
`Moreover, access terminal 122 is in communication with
`antennas 104 and 106, where antennas 104 and 106 transmit
`information to access terminal 122 over a forward link 124
`and receive information from access terminal 122 over a
`
`reverse link 126. In a frequency division duplex (FDD)sys-
`tem, forward link 118 can utilize a different frequency band
`thanthat used by reverse link 120, and forward link 124 can
`employ a different frequency band than that employed by
`reverse link 126, for example. Further, in a time division
`duplex (TDD) system, forward link 118 andreverse link 120
`can utilize a common frequency band and forward link 124
`and reverse link 126 can utilize a common frequency band.
`Each group of antennas and/or the area in which they are
`designated to communicate can be referred to as a sector of
`base station 102. For example, antenna groups can be
`designed to communicate to access terminals in a sector ofthe
`areas covered by base station 102. In communication over
`forward links 118 and 124, the transmitting antennas of base
`station 102 can utilize beamforming to improve signal-to-
`noise ratio of forward links 118 and 124 for access terminals
`116 and 122. Also, while base station 102 utilizes beamform-
`ing to transmit to access terminals 116 and 122 scattered
`randomly through an associated coverage, access terminals in
`neighboring cells can be subject to less interference as com-
`pared to a basestation transmitting through a single antenna
`to all its access terminals.
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`US 8,634,313 B2
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`7
`FIG. 2 shows an example wireless communication system
`200. The wireless communication system 200 depicts one
`base station 210 and one access terminal 250 for sake of
`
`brevity. However, it is to be appreciated that system 200 can
`include more than one base station and/or more than one
`
`access terminal, wherein additional base stations and/or
`access terminals can be substantially similaror different from
`example base station 210 and access terminal 250 described
`below. In addition, it is to be appreciated that base station 210
`and/