THU MLU UULLULITE
`
`US009832686B2
`
`( 12 ) United States Patent
`Belghoul et al .
`
`( 10 ) Patent No . :
`( 45 ) Date of Patent :
`
`US 9 , 832 , 686 B2
`Nov . 28 , 2017
`
`( 54 ) PROCEDURES FOR 3GPP CIRCUIT
`SWITCHED FALLBACK
`( 71 ) Applicant : Apple Inc . , Cupertino , CA ( US )
`( 72 ) Inventors : Farouk Belghoul , Campbell , CA ( US ) ;
`David Boettger , San Jose , CA ( US ) ;
`Krisztian Kiss , Hayward , CA ( US ) ;
`Dawei Zhang , Saratoga , CA ( US ) ;
`Tarik Tabet , Los Gatos , CA ( US ) ;
`Rafael L . Rivera - Barreto , Santa Clara ,
`CA ( US ) ; Huarui Liang , Beijing ( CN )
`( 73 ) Assignee : Apple Inc . , Cupertino , CA ( US )
`Subject to any disclaimer , the term of this
`( * ) Notice :
`patent is extended or adjusted under 35
`U . S . C . 154 ( b ) by 177 days .
`( 21 ) Appl . No . : 14 / 791 , 687
`( 22 ) Filed :
`Jul . 6 , 2015
`Prior Publication Data
`( 65 )
`US 2016 / 0007240 A1 Jan . 7 , 2016
`
`Related U . S . Application Data
`( 60 ) Provisional application No . 62 / 021 , 254 , filed on Jul .
`7 , 2014 .
`Int . Cl .
`H04L 12 / 28
`H04W 36 / 00
`
`( 51 )
`
`( 52 )
`
`( 58 )
`
`( 2006 . 01 )
`( 2009 . 01 )
`( Continued )
`U . S . CI .
`CPC . . . . . . . H04W 36 / 0022 ( 2013 . 01 ) ; H04W 36 / 14
`( 2013 . 01 ) ; H04W 48 / 16 ( 2013 . 01 ) ;
`( Continued )
`Field of Classification Search
`CPC . . . . . . . . . .
`( Continued )
`
`. . . . . . . . . . .
`
`. . . . .
`
`H04L 12 / 12
`
`( 56 )
`
`References Cited
`U . S . PATENT DOCUMENTS
`2013 / 0070728 A1
`3 / 2013 Umatt et al .
`4 / 2013 Pragada . . . . . . . . . . . . . . . . HO4W 16 / 14
`2013 / 0088983 A1 *
`370 / 252
`
`EP
`WO
`
`( Continued )
`FOREIGN PATENT DOCUMENTS
`2249607 A1 11 / 2010
`2013020000 AL
`2 / 2013
`( Continued )
`OTHER PUBLICATIONS
`International Search Report & Written Opinion , Application No .
`PCT / US2015 / 039216 , dated Oct . 8 , 2015 , 13 pages .
`( Continued )
`Primary Examiner — Dang Ton
`( 74 ) Attorney , Agent , or Firm — Meyertons Hood Kivlin
`Kowert & Goetzel , P . C . ; Jeffrey C . Hood
`( 57 )
`ABSTRACT
`Mobile devices , base stations , and / or relay stations may
`implement CSFB ( circuit switched fallback ) operations by
`using RRC ( radio resource control ) connection release and /
`or handover procedures . If the CSFB RAT ( radio access
`technology ) target is not well configured , the UE may be
`informed and provisioned by the NW during a CSFB pro
`cedure with the information to return to LTE . Having this
`information , the UE may perform an autonomous search of
`LTE cells after the CSFB call release , speeding up return to
`LTE . To minimize potential call failures during CSFB , the
`UE may autonomously perform an additional cell search , in
`particular a search for cells on a RAT different from the
`initial target RAT . This creates an opportunity to prevent call
`failure of CSFB calls that would otherwise fail . The UE may
`be provisioned during the CSFB procedure with information
`to perform the additional cell search , should such a search be
`necessary .
`
`16 Claims , 9 Drawing Sheets
`
`UE 106B
`
`Base
`Station
`102
`
`UE
`
`1064 m
`
`Network
`100
`
`UE
`106N
`
`

`

`US 9 , 832 , 686 B2
`Page 2
`
`WO
`WO
`
`FOREIGN PATENT DOCUMENTS
`2014085191 A2
`6 / 2014
`2015001387
`1 / 2015
`OTHER PUBLICATIONS
`" Geran LTE Interworking Issues with Legacy Systems ” , Research
`in Motion UK Ltd . , Vodafone Group Plc , May 11 - 15 , 2009 , 4 pages ,
`3rd Generation Partnership Project , Shenzhen , P . R . China .
`“ Reselection to E - UTRAN following CS fallback ” , Research In
`Motion UK Limited , Vodafone , AT & T , Feb . 22 - 26 , 2010 , 2 pages ,
`San Francisco , USA .
`Written Opinion for International Application No . PCT / US2015 /
`039216 , dated Aug . 6 , 2016 , pp . 1 - 7 .
`Ericsson , ST - Ericsson , NTT Docomo , TeliaSonera , AT & T , Softbank
`Mobile , China Unicorn : “ Re - direction to EUTRA Issues , ” 3GPP
`TSG - RAN WG2 * 78 , R2 - 122709 , Prague , Czech Republic , May
`21 - 25 , 2012 , pp . 1 - 6 .
`* cited by examiner
`
`( 52 )
`
`( 58 )
`
`( 56 )
`
`( 51 )
`
`Int . Cl .
`( 2009 . 01 )
`H04W 76 / 04
`H04W 48 / 16
`( 2009 . 01 )
`H04W 36 / 14
`( 2009 . 01 )
`( 2009 . 01 )
`H04W 48 / 18
`H04W 88 / 06
`( 2009 . 01 )
`U . S . CI .
`CPC . . . . . . H04W 76 / 046 ( 2013 . 01 ) ; H04W 36 / 0083
`( 2013 . 01 ) ; H04W 48 / 18 ( 2013 . 01 ) ; H04W
`88 / 06 ( 2013 . 01 )
`Field of Classification Search
`370 / 331
`USPC . . . . . . . . . . . . . . . . . .
`See application file for complete search history .
`References Cited
`U . S . PATENT DOCUMENTS
`2014 / 0247730 AL
`9 / 2014 Thota et al .
`2014 / 0302845 Al
`10 / 2014 Kim et al .
`
`

`

`U . S . Patent
`
`Nov . 28 , 2017
`
`Sheet 1 of 9
`
`1
`US 9 , 832 , 686 B2
`
`UE
`106B
`
`UE
`106A
`
`UE
`106N
`
`Network
`100
`
`Base
`Station
`102
`
`Base
`Station
`102
`
`FIG . 1
`
`106
`
`- O
`
`FIG . 2
`
`

`

`U . S . Patent
`
`Nov . 28 , 2017
`
`Sheet 2 of 9
`
`US 9 , 832 , 686 B2
`
`106
`
`NAND
`310
`
`Memory
`306
`
`ROM
`350
`
`Dock
`VE
`320
`
`SOC
`300
`
`MMU
`340
`
`Processor ( s )
`302
`
`Display
`Circuitry
`304
`
`Radio GSM ,
`BT , WiFi
`330
`
`FIG . 3
`
`Display
`340
`
`Antenna
`335
`
`

`

`U . S . Patent
`
`Nov . 28 , 2017
`
`Sheet 3 of 9
`
`US 9 , 832 , 686 B2
`
`BS 102
`
`Memory
`460
`
`ROM
`450
`
`Network
`Port
`470
`
`MMU
`440
`
`presentants
`
`Processor ( s )
`404
`
`Radio
`430
`
`Communication
`Chain
`432
`
`Antenna
`434
`
`FIG . 4
`
`

`

`U . S . Patent
`
`Nov . 28 , 2017
`
`Sheet 4 of 9
`
`US 9 , 832 , 686 B2
`
`Base
`Station
`102A
`
`Core
`Network
`100A
`
`Core
`Network
`100B
`
`ele
`
`Base
`Station
`102B
`
`UE
`106
`
`External
`Network
`108
`
`FIG . 5
`
`

`

`U . S . Patent
`
`Nov . 28 , 2017
`
`Sheet 5 of 9
`
`US 9 , 832 , 686 B2
`
`.
`
`MME 152
`
`SGSN 154
`
`6 MSC Server 156
`
`FIG . 6
`
`
`
`
`
`UMTS ( UTRAN GSM ( GERAN ) 3GPP Legacy Networks 144
`
`LTE ( E - UTRAN ) 142
`
`UE 106
`
`

`

`U . S . Patent
`
`Nov . 28 , 2017
`
`Sheet 6 of 9
`
`US 9 , 832 , 686 B2
`
`UE receives a message ( RRC connection release message or a Mobility From
`EUTRA Command message ) to transition from a first NW ( operating according to a
`first RAT ) to a second NW ( operating according to a second RAT )
`702
`
`Does the message include an
`indication of whether the UE is to perform autonomous
`search after ( CSFB ) call release ?
`704
`
`Yes
`
`Is the indication
`for the UE to perform the
`autonomous search ?
`706
`
`UE operates
`according to
`legacy beahvior
`708
`
`Yes
`
`The UE does not begin a first RAT cell
`( e . g . LTE cell ) search upon return to idle
`after a call in the second NW ( e . g . after a
`CSFB call ) , even if first RAT neighboring
`cell ( e . g . LTE neighboring cell )
`information is received during connection
`release on the first ?AT .
`710
`
`The UE immediately begins a first RAT cell ( e . g .
`LTE cell ) search upon return to idle after a call in
`the second NW ( e . g . after a CSFB call ) . The UE
`performs the cell search in priority order according
`to a priority list also received by the UE in the
`message , with the priority list containing a list of
`radio frequency channel numbers associated with
`the first RAT ( e . g . EARFCN ) to use by the UE .
`712
`
`FIG . 7
`
`

`

`U . S . Patent
`
`Nov . 28 , 2017
`
`Sheet 7 of 9
`
`US 9 , 832 , 686 B2
`
`UE receives a message ( e . g . an RRC connection release message ) to transition from
`a first NW operating according to a first RAT to a second NW operating according to
`a second RAT
`802
`
`Does the message include an
`indication of an alternative carrier frequency to be used
`for a call ( e . g . CSFB call ) to be conducted in an NW operating
`according to a different RAT than the first RAT ?
`804
`
`No
`
`No further search
`by UE is needed
`810
`
`Yes
`
`Cell search performed
`by UE according to a first
`information list fails ?
`808
`
`Yes
`
`UE operates
`according to
`legacy beahvior
`806
`
`The UE performs a new search according to an alternate cell
`information list received in the message along with the indication .
`The alternate cell information list contains radio access technology
`and cell information to be used by the UE ( for conducting the call
`in a NW operating according to a different RAT than the first RAT )
`in case the cell search performed by the UE according to the first
`list fails .
`812
`
`FIG . 8
`
`

`

`atent
`
`Nov . 28 , 2017
`
`Sheet 8 of 9
`
`US 9 , 832 , 686 B2
`
`- - ASN1START
`
`RRCConnection Release : : = SEQUENCE {
`rrc - Transaction dentifier RRC - Transactionldentifier ,
`criticalExtensions CHOICE {
`c1
`CHOICE {
`rrcConnectionRelease - r8 RRCConnectionRelease - r8 - IES ,
`spare3 NULL , spare2 NULL , spare1 NULL
`criticalExtensions Future SEQUENCE { }
`
`}
`on CriticalExtension RRCConnection Release - v890 - IES OPTIONAL
`}
`CS - Fallback - UE - EUTRAReturn BOOLEAN ;
`EUTRAReturn PriorityCarrierFreq ARFCN - ValueEUTRA OPTIONAL , - - Need OP
`
`FIG . 9
`
`- - ASN1START
`
`MobilityFromEUTRACommand : : = SEQUENCE {
`rrc - Transactionldentifier RRC - Transactionldentifier ,
`criticalExtensions CHOICE {
`c1
`CHOICE {
`mobilityFromEUTRACommand - r8 MobilityFromEUTRACommand - r8 - IES ,
`mobility FromEUTRACommand - r9 MobilityFromEUTRACommand - r9 - IES ,
`spare2 NULL , spare1 NULL
`
`}
`criticalExtensionsFuture SEQUENCE { }
`
`CS - Fallback - UE - EUTRAReturn BOOLEAN ;
`EUTRAReturn PriorityCarrier Freq ARFCN - ValueEUTRA OPTIONAL , - - Need OP
`
`FIG . 10
`
`

`

`U . S . Patent
`
`Nov . 28 , 2017
`
`Sheet 9 of 9
`
`US 9 , 832 , 686 B2
`
`- - ASN1START
`RRCConnection Release - r8 - IES : : = SEQUENCE {
`releaseCause ReleaseCause ,
`redirectedCarrierinfo RedirectedCarrierInfo OPTIONAL , - - Need ON
`redirectedCarrierInfo2 Redirected Carrierinfo2 OPTIONAL , - - Need ON
`idle Mode Mobility Controllnfo IdleMode Mobility ControlInfo OPTIONAL , - - Need OP
`non CriticalExtension RRCConnectionRelease - v890 - IES OPTIONAL
`??
`
`RedirectedCarrierInfo2 : : = CHOICE {
`eutra ARFCN - ValueEUTRA ,
`geran CarrierFreqsGERAN ,
`utra - FDD ARFCN - ValueUTRA ,
`utra - TDD ARFCN - ValueUTRA ,
`cdma 2000 - HRPD Carrier FreqCDMA2000 ,
`cdma 2000 - 1xRTT Carrier FreqCDMA2000 ,
`utra - TDD - r10 CarrierFreqListUTRA - TDD - r10
`
`RRCConnection Release - v920 - IES : : = SEQUENCE {
`cellInfoList - r9 CHOICE {
`geran - r9 CellInfoListGERAN - r9 ,
`utra - FDD - r9 CellinfoListUTRA - FDD - r9 ,
`utra - TDD - r9 CellinfoListUTRA - TDD - r9 ,
`
`. . .
`
`utra - TDD - r10 CellinfoListUTRA - TDD - r10
`
`}
`cellinfoList2 - 19 CHOICE {
`geran - r9 CellinfoListGERAN - r9 ,
`utra - FDD - r9 CellinfoListUTRA - FDD - r9 ,
`utra - TDD - r9 CellinfoListUTRA - TDD - r9 ,
`. .
`utra - TDD - r10 CellinfoListUTRA - TDD - r10
`
`OPTIONAL , - - Cond Redirection
`nonCriticalExtension RRCConnection Release - v1020 - IES OPTIONAL
`
`CS - Fallback - UE - EUTRAReturn BOOLEAN ;
`EUTRAReturn Priority Carrier Freq ARFCN - ValueEUTRA OPTIONAL , - - Need OP
`
`FIG . 11
`
`

`

`US 9 , 832 , 686 B2
`therefore , can provide services quickly . However , the dis
`PROCEDURES FOR 3GPP CIRCUIT
`advantage is longer call setup delay . While VoLTE has been
`SWITCHED FALLBACK
`widely accepted as the desired solution for the future , the
`PRIORITY CLAIM
`demand for voice calls today has led LTE carriers to
`5 introduce CSFB as a stopgap measure . When placing or
`This application claims benefit of priority of U . S . Provi -
`receiving a voice call , LTE handsets fall back to 2G or 3G
`sional Patent Application Ser . No . 62 / 021 , 254 titled
`networks for the duration of the call .
`“ Enhanced Procedures for 3GPP Circuit Switched Fall
`In other words , while 3GPP ( Third Generation Partner
`back ” , filed on Jul . 7 , 2014 , which is hereby incorporated by
`ship Project ) LTE technology has reached a certain level of
`reference as though fully and completely set forth herein .
`10 maturity , there continues to be innovation in the area of
`network deployments strategies , the result of which are
`FIELD OF THE INVENTION
`challenges to the user experience regarding voice calls .
`Furthermore , existing LTE network deployments continue to
`The present application relates to wireless communica -
`expose " corner cases ”
`in which the voice calling user
`tion , and more particularly to enhanced procedures for 15 experience is sub - par . CSFB has been launched commer
`providing circuit switched fallback among 3GPP wireless
`cially by multiple MNOS ( Mobile Network Operators ) .
`Compared to native CS calls , CSFB deployments continue
`communications devices .
`to expose various problems such as additional call setup
`DESCRIPTION OF THE RELATED ART
`time , IRAT ( Inter - Radio Access Technology ) cell re - selec
`20 tion / handover failures and the inefficient return back to
`Wireless communication systems are rapidly growing in
`E - UTRAN ( Evolved Universal Terrestrial Access Network ) ,
`all of which severely impact user experience .
`usage . In recent years , wireless devices such as smart phones
`and tablet computers have become increasingly sophisti
`SUMMARY OF THE INVENTION
`cated . In addition to supporting telephone calls , many
`mobile devices now provide access to the internet , email , 25
`an
`to
`text messaging , and navigation using the global positioning
`Embodiments described herein
`are directed
`system ( GPS ) , and are capable of operating sophisticated
`improvement of 3GPP standards that allow UE ( User Equip
`applications that utilize these functionalities .
`ment ) autonomous behavior ( using network support ) to
`Long Term Evolution ( LTE ) is the technology of choice
`improve CSFB performance . Various embodiments of LTE
`for the majority of wireless network operators worldwide , 30 communications and network ( NW ) equipment , including
`providing mobile broadband data and high - speed Internet
`UE devices , base stations and / or relay stations , and associ
`access to their subscriber base . LTE defines a number of
`ated methods described herein facilitate improved CSFB
`downlink ( DL ) physical channels , categorized as transport
`performance during wireless communications , e . g . wireless
`or control channels , to carry information blocks received
`communications that involve LTE communications and
`from the MAC and higher layers . LTE also defines three 35 transmissions . Specifically , various embodiments described
`physical layer channels for the uplink ( UL ) . The LTE
`herein facilitate improved fast return to LTE upon CSFB call
`standard supports packet switching with its all - IP network .
`release , and a reduction in CSFB call failure .
`However , voice calls in any of the wireless communication
`CSFB still plays an important role in deployed LTE
`standards , such as GSM ( Global Systems for Mobile ) ,
`networks . Compared to a native call starting in 2G or 3G CS
`UMTS ( Universal Mobile Telecommunications System ) and 40 domains , CSFB has longer call setup times . Increased call
`CDMA2000 ( Code Division Multiple Access 2000 ) are
`setup times can be observed in LTE to UMTS CSFB and
`circuit switched , so with the adoption of LTE , carriers
`LTE to GSM CSFB , for example , especially if the already
`modified their voice call network in order to accommodate
`standardized solutions to optimize the call setup times are
`not possible to deploy , e . g . , due to impact on both GERAN
`LTE .
`Three different approaches were taken in ensuring the 45 ( GSM EDGE Radio Access Network ) and E - UTRAN . Some
`seamless transmission of both voice calls and data over LTE .
`operators have elected not to upgrade their GERAN /
`One approach is Voice over LTE ( VoLTE ) , which is based on
`UTRAN when deploying E - UTRAN together with CSFB . In
`the Internet Protocol Multimedia Subsystem ( IMS ) network ,
`these cases , BSS ( Base Station Subsystems ) and RNS ( Ra
`with specific profiles for control and media planes of voice
`dio Network Subsystems ) cannot use the Rel - 10 Fast Return
`service on LTE defined by GSMA ( GSM Association ) in 50 procedures to send the UE back to E - UTRAN immediately
`PRD ( Products Requirement Document ) IR . 92 . The voice
`after CSFB call release . As result , the UE behavior after a
`service is delivered as data flows within the LTE data bearer .
`CSFB call can be unpredictable . The UE can remain in
`Consequently , there is no dependency on the legacy Circuit
`GERAN / UTRAN for a long time with a degraded user
`Switched Voice Network ( CSVN ) . In Simultaneous voice
`experience . Current CSFB deployments also show a signifi
`and LTE ( SVLTE ) , the mobile device operates simultane - 55 cant failure rate of cell reselection / handover on the target
`ously in the LTE and circuit switched ( CS ) modes , with the
`RAT ( Radio Access Technology ) during CSFB procedures ,
`LTE mode providing data services and the CS mode pro -
`which can cause the call setup process to fail . Since some
`viding the voice service . This is a solution solely based on
`operators expect that CSFB will continue to play an impor
`the device , which does not have special requirements on the
`tant role for some time to come , there is interest in reducing
`network and does not require the deployment of IMS . 60 the CSFB call setup times and also improving other aspects
`However , this solution can require expensive phones with
`of CSFB procedures such as the efficient and fast return to
`E - UTRAN after CSFB triggered call release and resolving
`high power consumption .
`A third approach is referred to as CS fallback ( CSFB ) ,
`abnormal call setup scenarios .
`There is room for enhancement or improvement in CSFB
`according to which LTE provides data services , but when a
`voice call is initiated or received , communication falls back 65 procedures for enabling efficient and fast return to
`to the CS domain . Operators may simply upgrade the MSC
`E - UTRAN after CSFB triggered call release without intro
`( Mobile Service Center ) instead of deploying the IMS , and
`ducing enhancements to the A / Iu interface in GERAN /
`
`

`

`US 9 , 832 , 686 B2
`
`5
`
`FIG . 3 illustrates an exemplary block diagram of a UE , in
`UTRAN , and addressing and resolving abnormal call setup
`accordance with some embodiments ;
`scenarios . The adopted enhancements may be designed such
`FIG . 4 illustrates an exemplary block diagram of a base
`that they do not affect CSFB for UEs to which the enhance
`station , in accordance with some embodiments ;
`ments are not applicable . That is , CSFB enhancements may
`be designed using existing UE operations .
`FIG . 5 is an exemplary block diagram of a cellular
`communication network , in accordance with some embodi
`The significant failure rate of cell reselection / handover on
`ments ;
`the target RAT during CSFB procedures ( which can result in
`FIG . 6 is a more detailed block diagram of one example
`failure of the call setup process ) may be caused by non
`of a cellular communication network that includes both an
`optimal legacy RAN ( Radio Access Network ) target cell
`LTE and a 3GPP network , in accordance with some embodi
`lists or excessive RF ( Radio Frequency ) interference on the
`ments ;
`target RAT . In case of potential call failures during CSFB ,
`FIG . 7 is a flowchart diagram illustrating one example of
`the UE can autonomously perform an additional cell search ,
`a method for providing improved return to LTE during
`in particular a search for cells on a RAT different from the
`initial target RAT . This creates the opportunity to “ rescue ” 16 CSFB operations , according to one set of embodiments ;
`FIG . 8 is a flowchart diagram illustrating one example of
`CSFB calls that would otherwise fail .
`Accordingly , in one set of embodiments , mobile devices ,
`a method for providing reduced call failure during CSFB
`base stations , and / or relay stations may implement a method
`operations , according to one set of embodiments ;
`for improved CSFB operations by using RRC ( Radio
`FIG . 9 shows one example of a code segment for imple
`Resource Control ) connection release procedures and / or 20 menting an updated RRC Connection Release message ,
`handover procedures . If the CSFB target RAT is not well
`according to some embodiments ;
`configured ( e . g . no LTE cells are broadcasting in the original
`FIG . 10 shows one example of a code segment for
`target RAT ) , the UE may be informed and provisioned by the
`implementing an updated Mobility from EUTRA Command
`NW with information during CSFB procedures to return to
`message , according to some embodiments ; and
`LTE . Having this information , the UE may perform an 25
`FIG .
`11 shows one example of a code segment for
`autonomous search of LTE cells after the CSFB call release ,
`implementing a further updated RRC Connection Release
`and thereby speed up return to LTE . For example , under the
`message , according to some embodiments .
`present standard , ending a CSFB call can result in the UE
`While features described herein are susceptible to various
`remaining on the legacy RAT . However , the NW may
`modifications and alternative forms , specific embodiments
`provide instruction and information via messaging during 30 thereof are shown by way of example in the drawings and
`the CSFB communications that authorizes the UE to per -
`are herein described in detail . It should be understood ,
`form an autonomous search upon release of the CSFB call ,
`however , that the drawings and detailed description thereto
`according to the information provided by the NW during the
`are not intended to be limiting to the particular form dis
`messaging . This prevents the UE from camping out in the
`closed , but on the contrary , the intention is to cover all
`legacy RAT upon release of the CSFB call . The additional 35 modifications , equivalents and alternatives falling within the
`information and instruction may be transmitted to the UE in
`spirit and scope of the subject matter as defined by the
`an RRC connection release message or a Mobility from
`appended claims .
`EUTRA Command message for improved fast return to LTE
`DETAILED DESCRIPTION OF THE
`from CSFB . In some cases , the network ( e . g . base station )
`EMBODIMENTS
`may operate to provide instruction for the UE to perform an 40
`autonomous search upon the release of the CSFB call , but
`Acronyms
`without the network also providing the UE with the addi -
`Various acronyms are used throughout the present appli
`tional ( redirection ) information . In such instances , the UE
`cation . Definitions of the most prominently used acronyms
`may operate to autonomously search upon release of the
`CSFB call independently , and select a suitable LTE cell ( i . e . 45 that may appear throughout the present application are
`provided below :
`a suitable cell in EUTRA ) .
`ACK : Acknowledge
`In case of potential call failures during CSFB , the UE may
`autonomously perform an additional cell search , in particu
`AMR : Adaptive Multi - Rate
`lar , a search for cells on a RAT different from the initial
`ARQ : Automatic Repeat Request ( also : Automatic Repeat
`target RAT . This creates the opportunity to “ rescue ” CSFB 50
`Query )
`calls that would otherwise fail . That is , if an original target
`BPSK : Binary Phase - Shift Keying
`BS : Base Station
`RAT results in a failed search , additional instruction and
`information previously provided to the UE may authorize
`BS : Base Station Subsystem
`the UE to perform the additional cell search on a different
`BSR : Buffer Status Report
`target RAT according to the additional information . The 55
`CCE : Control Channel Elements
`additional information and instruction may be transmitted to
`CDMA : Code Division Multiple Access
`CDRX : Connected - Mode Discontinuous Reception
`the UE in an RRC connection release message for reducing
`CFI : Control Frame Indicator
`CSFB call failure .
`CQI : Channel Quality Indicator
`BRIEF DESCRIPTION OF THE DRAWINGS
`CRC : Cyclic Redundancy Check
`CS : Circuit - Switched
`FIG . 1 illustrates an exemplary ( and simplified ) wireless
`CSFB : Circuit - Switched Fallback
`CSVN : Circuit - Switched Voice Network
`communication system , in accordance with some embodi
`DCI : Downlink Control Information
`ments ;
`m
`FIG . 2 illustrates one example of a base station in com - 65
`DL : Downlink ( from BS to UE )
`munication with a wireless user equipment ( UE ) device , in
`DLSCH : Downlink Shared Channel
`ENB ( or eNB ) : eNodeB ( Base Station )
`accordance with some embodiments ;
`
`60
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`

`

`5
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`15
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`10
`
`US 9 , 832 , 686 B2
`intended to include an installation medium , e . g . , a CD
`E - UTRAN : Evolved Universal Terrestrial Access Net
`ROM , floppy disks 104 , or tape device ; a computer system
`work
`FDD : Frequency Division Duplexing
`memory or random access memory such as DRAM , DDR
`FEC : Forward Error Correction
`RAM , SRAM , EDO RAM , Rambus RAM , etc . , a non
`GERAN : GSM EDGE Radio Access Network
`volatile memory such as a Flash , magnetic media , e . g . , a
`GPS : Global Positioning System
`hard drive , or optical storage ; registers , or other similar
`GSM : Global System for Mobile Communication
`types of memory elements , etc . The memory medium may
`HARQ : Hybrid Automatic Repeat Request
`comprise other types of memory as well or combinations
`IE : Information Element
`thereof . In addition , the memory medium may be located in
`IMS : Internet Protocol Multimedia Subsystem
`a first computer system in which the programs are executed ,
`or may be located in a second different computer system
`LTE : Long Term Evolution
`MAC : Media Access Control ( layer )
`which connects to the first computer system over a network ,
`MIMO : Multiple - In Multiple - Out
`such as the Internet . In the latter instance , the second
`computer system may provide program instructions to the
`MME : Mobile Management Entity
`MNO : Mobile Network Operator
`first computer system for execution . The term
`" memory
`MSC : Mobile Service Center
`medium ” may include two or more memory mediums which
`MT : Mobile Terminating
`may reside in different locations , e . g . , in different computer
`MTRF : Mobile Terminating Roaming Forwarding
`systems that are connected over a network .
`NACK : Negative Acknowledge
`Carrier Medium a memory medium as described above ,
`20 as well as a physical transmission medium , such as a bus ,
`NAS : Non - Access Stratum
`network , and / or other physical transmission medium that
`NW : Wireless Network
`OAM : Operations , Administration , and Management
`conveys signals such as electrical , electromagnetic , or digi
`OFDM : Orthogonal Frequency - Division Multiplexing
`tal signals .
`Computer System ( or Computer ) any of various types of
`PCEF : Policy and Charging Enforcement Function
`25 computing or processing systems , including a personal
`PCFICH : Physical Control Format Indicator Channel
`computer system ( PC ) , mainframe computer system , work
`PDB : Packet Delay Budget
`station , network appliance , Internet appliance , personal digi
`PDCCH : Physical Downlink Control Channel
`PDCP : Packet Data Convergence Protocol
`tal assistant ( PDA ) , television system , grid computing sys
`PDSCH : Physical Downlink Shared Channel
`tem , or other device or combinations of devices . In general ,
`PDU : Protocol Data Unit
`30 the term “ computer system ” can be broadly defined to
`PHICH : Physical HARQ Indicator Channel
`encompass any device ( or combination of devices ) having at
`PHY : Physical ( Layer )
`least one processor that executes instructions from
`a
`memory medium .
`PS : Packet - Switched
`PUSCH : Physical Uplink Shared Channel
`User Equipment ( UE ) ( or “ UE Device ” ) — any of various
`35 types of computer systems devices which are mobile or
`QCI : Quality of Service Class Identifier
`QoS : Quality of Service
`portable and which performs wireless communications .
`QPSK : Quadrature Phase - Shift Keying
`Examples of UE devices include mobile telephones or smart
`phones ( e . g . , iPhoneTM , AndroidTM - based phones ) , portable
`RACH : Random Access Procedure
`RAT : Radio Access Technology
`gaming devices ( e . g . , Nintendo DSTM , PlayStation Por
`40 tableTM , Gameboy AdvanceTM , iPhoneTM ) , wearable elec
`REG : Resource Element Group
`tronic devices ( e . g . Apple WatchTM , Google GlassTM ) , lap
`RLC : Radio Link Control
`tops , PDAs , portable Internet devices , music players , data
`RNC : Radio Network Controller
`RNS : Radio Network Subsystems
`storage devices , or other handheld devices , etc . In general ,
`RNTI : Radio Network Temporary Identifiers
`the term “ UE ” or “ UE device " can be broadly defined to
`RRC : Radio Resource Control
`45 encompass any electronic , computing , and / or telecommuni
`RSRP : Reference Signal Received Power
`cations device ( or combination of devices ) which is easily
`RSRQ : Reference Signal Received Quality
`transported by a user and capable of wireless communica
`RSSI : Reference Signal Strength Indicator
`tion .
`RTP : Real - time Transport Protocol
`Base Station ( BS ) — The term “ Base Station ” has the full
`RX : Reception
`50 breadth of its ordinary meaning , and at least includes a
`SINR : Signal - To - Interference - Plus - Noise Ratio
`wireless communication station installed at a fixed location
`and used to communicate as part of a wireless telephone
`SRVCC : Single Radio - Voice Call Continuity
`system or radio system .
`SVLTE : Simultaneous Voice and LTE
`TB : Transport Blocks
`Processing Element — refers to various elements or com
`TDD : Time Division Duplexing
`55 binations of elements . Processing elements include , for
`example , circuits such as an ASIC ( Application Specific
`TTI : Transmission Time Interval
`Integrated Circuit ) , portions or circuits of individual proces
`TX : Transmission
`UE : User Equipment
`sor cores , entire processor cores , individual processors ,
`UL : Uplink ( from UE to BS )
`programmable hardware devices such as a field program
`ULSCH : Uplink Shared Channel
`60 mable gate array ( FPGA ) , and / or larger portions of systems
`that include multiple processors .
`UMTS : Universal Mobile Telecommunication System
`Automatically - refers to an action or operation per
`VOLTE : Voice over Long Term Evolution
`formed by a computer system ( e . g . , software executed by the
`Terms
`computer system ) or device ( e . g . , circuitry , programmable
`The following is a glossary of terms that may appear in
`the present application :
`65 hardware elements , ASICs , etc . ) , without user input directly
`specifying or performing the action or operation . Thus the
`Memory Medium — Any of various types of memory
`term “ automatically ” is
`in contrast to an operation being
`devices or storage devices . The term “ memory medium ” is
`
`

`

`US 9 , 832 , 686 B2
`
`CDMA2000 ( e . g . , 1xRTT , 1xEV - DO , HRPD , HRPD ) ,
`manually performed or specified by the user , where the user
`Wi - Fi , WiMAX etc . In some embodiments , the base station
`provides input to directly perform the operation . An auto
`102 communicates with at least one UE using improved UL
`matic procedure may be initiated by input provided by the
`( Uplink ) and DL ( Downlink ) decoupling , preferably through
`user , but the subsequent actions that are performed “ auto
`5 LTE or a similar RAT standard .
`matically ” are not specified by the user , i . e . , are not per -
`UE 106 may be capable of communicating using multiple
`formed “ manually ” , where the user specifies each action to
`wireless communication standards . For example , a UE 106
`perform . For example , a user filling out an electronic form
`might be configured to communicate using either or both of
`by selecting each field and providing input specifying infor -
`a 3GPP cellular communication standard ( such as LTE ) or a
`mation ( e . g . , by typing information , selecting check boxes ,
`radio selections , etc . ) is filling out the form manually , even 10 3GPP2 cellular communication standard ( such as a cellular
`though the computer system must update the form in
`communication standard in the CDMA2000 family of cel
`response to the user actions . The form may be automatically
`lular communication standards ) . In some embodiments , the
`filled out by the computer system where the computer
`UE 106 may be configured to communicate with base station
`system ( e . g . , software executing on the computer system )
`102 according to improved UL and DL decoupling methods
`analyzes the fields of the form and fills in the form without 15 as described herein . Base station 102 and other similar base
`any user input specifying the answers to the fields . As stations operating according to the same or a different
`indicated above , the user may invoke the automatic filling of
`cellular communication standard may thus be provided as
`the form , but is not involved in the actual filling of the form
`one or more networks of cells , which may provide continu
`(