US9271199B2 - Managing system frame numbers (SFNs) for circuit-switched fallback (CSFB) - Google Patents

Managing system frame numbers (SFNs) for circuit-switched fallback (CSFB) Download PDF

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US9271199B2
US9271199B2 US14/088,018 US201314088018A US9271199B2 US 9271199 B2 US9271199 B2 US 9271199B2 US 201314088018 A US201314088018 A US 201314088018A US 9271199 B2 US9271199 B2 US 9271199B2
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Prior art keywords
sfn
rat
frame number
difference
system frame
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US14/088,018
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US20150148043A1 (en
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Ming Yang
Tom Chin
Guangming Shi
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Qualcomm Inc
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Qualcomm Inc
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Assigned to QUALCOMM INCORPORATED reassignment QUALCOMM INCORPORATED ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SHI, GUANGMING, CHIN, TOM, YANG, MING
Priority to KR1020167015958A priority patent/KR20160089407A/ko
Priority to EP14802243.7A priority patent/EP3072327A1/fr
Priority to CN201480061287.7A priority patent/CN105706493A/zh
Priority to PCT/US2014/062846 priority patent/WO2015076994A1/fr
Priority to JP2016531994A priority patent/JP2017500784A/ja
Priority to TW103138222A priority patent/TWI566558B/zh
Publication of US20150148043A1 publication Critical patent/US20150148043A1/en
Publication of US9271199B2 publication Critical patent/US9271199B2/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0011—Control or signalling for completing the hand-off for data sessions of end-to-end connection
    • H04W36/0022—Control or signalling for completing the hand-off for data sessions of end-to-end connection for transferring data sessions between adjacent core network technologies
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0011—Control or signalling for completing the hand-off for data sessions of end-to-end connection
    • H04W36/0022—Control or signalling for completing the hand-off for data sessions of end-to-end connection for transferring data sessions between adjacent core network technologies
    • H04W36/00224—Control or signalling for completing the hand-off for data sessions of end-to-end connection for transferring data sessions between adjacent core network technologies between packet switched [PS] and circuit switched [CS] network technologies, e.g. circuit switched fallback [CSFB]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0055—Transmission or use of information for re-establishing the radio link
    • H04W36/0066—Transmission or use of information for re-establishing the radio link of control information between different types of networks in order to establish a new radio link in the target network
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
    • H04W36/0085—Hand-off measurements
    • H04W36/0088—Scheduling hand-off measurements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/14—Reselecting a network or an air interface
    • H04W36/144—Reselecting a network or an air interface over a different radio air interface technology
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/02—Terminal devices
    • H04W88/06—Terminal devices adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Definitions

  • aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to utilizing system frame numbers (SFNs) to determine a transmission time interval (TTI) boundary during redirection from one radio access technology (RAT) to another.
  • SFNs system frame numbers
  • TTI transmission time interval
  • Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on.
  • Such networks which are usually multiple access networks, support communications for multiple users by sharing the available network resources.
  • the Universal Terrestrial Radio Access Network (UTRAN).
  • the UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP).
  • UMTS Universal Mobile Telecommunications System
  • 3GPP 3rd Generation Partnership Project
  • the UMTS which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA).
  • W-CDMA Wideband-Code Division Multiple Access
  • TD-CDMA Time Division-Code Division Multiple Access
  • TD-SCDMA Time Division-Synchronous Code Division Multiple Access
  • the UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks.
  • HSPA is a collection of two mobile telephony protocols, High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA), that extends and improves the performance of existing wideband protocols.
  • HSPA High Speed Packet Access
  • HSPA High Speed Downlink Packet Access
  • HSUPA High Speed Uplink Pack
  • a method of wireless communication includes recording an absolute system frame number (SFN) of a target radio access technology (RAT) and/or a relative system frame number (SFN) difference between a serving radio access technology (RAT) and the target RAT.
  • SFN absolute system frame number
  • SFN relative system frame number
  • a transmission time interval (TTI) boundary, after redirection, is then determined based at least in part on the recorded absolute frame number (SFN) and/or the recorded relative system frame number (SFN) difference.
  • TTI transmission time interval
  • an apparatus including means for recording an absolute system frame number (SFN) of a target radio access technology (RAT) and/or a relative system frame number (SFN) difference between a serving radio access technology (RAT) and the target RAT. Also included is a mean for determining a transmission time interval (TTI) boundary, after redirection, based at least in part on the recorded absolute frame number (SFN) and/or the recorded relative system frame number (SFN) difference.
  • SFN absolute system frame number
  • RAT radio access technology
  • SFN relative system frame number
  • TTI transmission time interval
  • a computer program product for wireless communications in a wireless network having a non-transitory computer-readable medium has non-transitory program code recorded thereon which, when executed by the processor(s), causes the processor(s) to perform operations of recording an absolute system frame number (SFN) of a target radio access technology (RAT) and/or recording a relative system frame number (SFN) difference between a serving radio access technology (RAT) and the target RAT.
  • the program code also causes the processor(s) to determine a transmission time interval (TTI) boundary, after redirection, based at least in part on the recorded absolute frame number (SFN) and/or the recorded relative system frame number (SFN) difference.
  • TTI transmission time interval
  • wireless communication having a memory and at least one processor coupled to the memory.
  • the processor(s) is configured to record an absolute system frame number (SFN) of a target radio access technology (RAT) and/or record a relative system frame number (SFN) difference between a serving radio access technology (RAT) and the target RAT.
  • the processor(s) is also configured to determine a transmission time interval (TTI) boundary, after redirection, is then determined based at least in part on the recorded absolute frame number (SFN) and/or the recorded relative system frame number (SFN) difference.
  • TTI transmission time interval
  • FIG. 1 is a block diagram conceptually illustrating an example of a telecommunications system.
  • FIG. 2 is a block diagram conceptually illustrating an example of a frame structure in a telecommunications system.
  • FIG. 3 is a block diagram conceptually illustrating an example of a node B in communication with a UE in a telecommunications system.
  • FIG. 4 illustrates network coverage areas according to aspects of the present disclosure.
  • FIG. 5 is a call flow diagram illustrating an aspect of the present disclosure.
  • FIG. 6 is a block diagram illustrating a method for determining a transmission time interval according to one aspect of the present disclosure.
  • FIG. 7 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system according to one aspect of the present disclosure.
  • FIG. 1 a block diagram is shown illustrating an example of a telecommunications system 100 .
  • the various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards.
  • the aspects of the present disclosure illustrated in FIG. 1 are presented with reference to a UMTS system employing a TD-SCDMA standard.
  • the UMTS system includes a (radio access network) RAN 102 (e.g., UTRAN) that provides various wireless services including telephony, video, data, messaging, broadcasts, and/or other services.
  • RAN 102 e.g., UTRAN
  • the RAN 102 may be divided into a number of Radio Network Subsystems (RNSs) such as an RNS 107 , each controlled by a Radio Network Controller (RNC) such as an RNC 106 .
  • RNC Radio Network Controller
  • the RNC 106 is an apparatus responsible for, among other things, assigning, reconfiguring and releasing radio resources within the RNS 107 .
  • the RNC 106 may be interconnected to other RNCs (not shown) in the RAN 102 through various types of interfaces such as a direct physical connection, a virtual network, or the like, using any suitable transport network.
  • the geographic region covered by the RNS 107 may be divided into a number of cells, with a radio transceiver apparatus serving each cell.
  • a radio transceiver apparatus is commonly referred to as a node B in UMTS applications, but may also be referred to by those skilled in the art as a base station (BS), a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), or some other suitable terminology.
  • BS basic service set
  • ESS extended service set
  • AP access point
  • two node Bs 108 are shown; however, the RNS 107 may include any number of wireless node Bs.
  • the node Bs 108 provide wireless access points to a core network 104 for any number of mobile apparatuses.
  • a mobile apparatus include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a notebook, a netbook, a smartbook, a personal digital assistant (PDA), a satellite radio, a global positioning system (GPS) device, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, or any other similar functioning device.
  • SIP session initiation protocol
  • PDA personal digital assistant
  • GPS global positioning system
  • multimedia device e.g., a digital audio player (e.g., MP3 player), a camera, a game console, or any other similar functioning device.
  • MP3 player digital audio player
  • the mobile apparatus is commonly referred to as user equipment (UE) in UMTS applications, but may also be referred to by those skilled in the art as a mobile station (MS), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology.
  • UE user equipment
  • MS mobile station
  • AT access terminal
  • three UEs 110 are shown in communication with the node Bs 108 .
  • the downlink (DL), also called the forward link refers to the communication link from a node B to a UE
  • the uplink (UL) also called the reverse link
  • the core network 104 includes a GSM core network.
  • GSM Global System for Mobile communications
  • the core network 104 supports circuit-switched services with a mobile switching center (MSC) 112 and a gateway MSC (GMSC) 114 .
  • MSC mobile switching center
  • GMSC gateway MSC
  • One or more RNCs, such as the RNC 106 may be connected to the MSC 112 .
  • the MSC 112 is an apparatus that controls call setup, call routing, and UE mobility functions.
  • the MSC 112 also includes a visitor location register (VLR) (not shown) that contains subscriber-related information for the duration that a UE is in the coverage area of the MSC 112 .
  • VLR visitor location register
  • the GMSC 114 provides a gateway through the MSC 112 for the UE to access a circuit-switched network 116 .
  • the GMSC 114 includes a home location register (HLR) (not shown) containing subscriber data, such as the data reflecting the details of the services to which a particular user has subscribed.
  • HLR home location register
  • the HLR is also associated with an authentication center (AuC) that contains subscriber-specific authentication data.
  • AuC authentication center
  • the core network 104 also supports packet-data services with a serving GPRS support node (SGSN) 118 and a gateway GPRS support node (GGSN) 120 .
  • GPRS which stands for General Packet Radio Service, is designed to provide packet-data services at speeds higher than those available with standard GSM circuit-switched data services.
  • the GGSN 120 provides a connection for the RAN 102 to a packet-based network 122 .
  • the packet-based network 122 may be the Internet, a private data network, or some other suitable packet-based network.
  • the primary function of the GGSN 120 is to provide the UEs 110 with packet-based network connectivity. Data packets are transferred between the GGSN 120 and the UEs 110 through the SGSN 118 , which performs primarily the same functions in the packet-based domain as the MSC 112 performs in the circuit-switched domain.
  • the UMTS air interface is a spread spectrum Direct-Sequence Code Division Multiple Access (DS-CDMA) system.
  • DS-CDMA Spread spectrum Direct-Sequence Code Division Multiple Access
  • the TD-SCDMA standard is based on such direct sequence spread spectrum technology and additionally calls for a time division duplexing (TDD), rather than a frequency division duplexing (FDD) as used in many FDD mode UMTS/W-CDMA systems.
  • TDD uses the same carrier frequency for both the uplink (UL) and downlink (DL) between a node B 108 and a UE 110 , but divides uplink and downlink transmissions into different time slots in the carrier.
  • FIG. 2 shows a frame structure 200 for a TD-SCDMA carrier.
  • the TD-SCDMA carrier as illustrated, has a frame 202 that is 10 ms in length.
  • the chip rate in TD-SCDMA is 1.28 Mcps.
  • the frame 202 has two 5 ms subframes 204 , and each of the subframes 204 includes seven time slots, TS0 through TS6.
  • the first time slot, TS0 is usually allocated for downlink communication, while the second time slot, TS1, is usually allocated for uplink communication.
  • the remaining time slots, TS2 through TS6, may be used for either uplink or downlink, which allows for greater flexibility during times of higher data transmission times in either the uplink or downlink directions.
  • a downlink pilot time slot (DwPTS) 206 , a guard period (GP) 208 , and an uplink pilot time slot (UpPTS) 210 are located between TS0 and TS1.
  • Each time slot, TS0-TS6, may allow data transmission multiplexed on a maximum of 16 code channels.
  • Data transmission on a code channel includes two data portions 212 (each with a length of 352 chips) separated by a midamble 214 (with a length of 144 chips) and followed by a guard period (GP) 216 (with a length of 16 chips).
  • the midamble 214 may be used for features, such as channel estimation, while the guard period 216 may be used to avoid inter-burst interference.
  • Synchronization Shift bits 218 are also transmitted in the data portion.
  • Layer 1 control information including Synchronization Shift (SS) bits 218 .
  • Synchronization Shift bits 218 only appear in the second part of the data portion.
  • the Synchronization Shift bits 218 immediately following the midamble can indicate three cases: decrease shift, increase shift, or do nothing in the upload transmit timing.
  • the positions of the SS bits 218 are not generally used during uplink communications.
  • FIG. 3 is a block diagram of a node B 310 in communication with a UE 350 in a RAN 300 , where the RAN 300 may be the RAN 102 in FIG. 1 , the node B 310 may be the node B 108 in FIG. 1 , and the UE 350 may be the UE 110 in FIG. 1 .
  • a transmit processor 320 may receive data from a data source 312 and control signals from a controller/processor 340 .
  • the transmit processor 320 provides various signal processing functions for the data and control signals, as well as reference signals (e.g., pilot signals).
  • the transmit processor 320 may provide cyclic redundancy check (CRC) codes for error detection, coding and interleaving to facilitate forward error correction (FEC), mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM), and the like), spreading with orthogonal variable spreading factors (OVSF), and multiplying with scrambling codes to produce a series of symbols.
  • BPSK binary phase-shift keying
  • QPSK quadrature phase-shift keying
  • M-PSK M-phase-shift keying
  • M-QAM M-quadrature amplitude modulation
  • OVSF orthogonal variable spreading factors
  • These channel estimates may be derived from a reference signal transmitted by the UE 350 or from feedback contained in the midamble 214 ( FIG. 2 ) from the UE 350 .
  • the symbols generated by the transmit processor 320 are provided to a transmit frame processor 330 to create a frame structure.
  • the transmit frame processor 330 creates this frame structure by multiplexing the symbols with a midamble 214 ( FIG. 2 ) from the controller/processor 340 , resulting in a series of frames.
  • the frames are then provided to a transmitter 332 , which provides various signal conditioning functions including amplifying, filtering, and modulating the frames onto a carrier for downlink transmission over the wireless medium through smart antennas 334 .
  • the smart antennas 334 may be implemented with beam steering bidirectional adaptive antenna arrays or other similar beam technologies.
  • a receiver 354 receives the downlink transmission through an antenna 352 and processes the transmission to recover the information modulated onto the carrier.
  • the information recovered by the receiver 354 is provided to a receive frame processor 360 , which parses each frame, and provides the midamble 214 ( FIG. 2 ) to a channel processor 394 and the data, control, and reference signals to a receive processor 370 .
  • the receive processor 370 then performs the inverse of the processing performed by the transmit processor 320 in the node B 310 . More specifically, the receive processor 370 descrambles and despreads the symbols, and then determines the most likely signal constellation points transmitted by the node B 310 based on the modulation scheme.
  • the soft decisions may be based on channel estimates computed by the channel processor 394 .
  • the soft decisions are then decoded and deinterleaved to recover the data, control, and reference signals.
  • the CRC codes are then checked to determine whether the frames were successfully decoded.
  • the data carried by the successfully decoded frames will then be provided to a data sink 372 , which represents applications running in the UE 350 and/or various user interfaces (e.g., display).
  • Control signals carried by successfully decoded frames will be provided to a controller/processor 390 .
  • the controller/processor 390 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.
  • ACK acknowledgement
  • NACK negative acknowledgement
  • a transmit processor 380 receives data from a data source 378 and control signals from the controller/processor 390 and provides various signal processing functions including CRC codes, coding and interleaving to facilitate FEC, mapping to signal constellations, spreading with OVSFs, and scrambling to produce a series of symbols.
  • the symbols produced by the transmit processor 380 will be provided to a transmit frame processor 382 to create a frame structure.
  • the transmit frame processor 382 creates this frame structure by multiplexing the symbols with a midamble 214 ( FIG. 2 ) from the controller/processor 390 , resulting in a series of frames.
  • the frames are then provided to a transmitter 356 , which provides various signal conditioning functions including amplification, filtering, and modulating the frames onto a carrier for uplink transmission over the wireless medium through the antenna 352 .
  • the uplink transmission is processed at the node B 310 in a manner similar to that described in connection with the receiver function at the UE 350 .
  • a receiver 335 receives the uplink transmission through the antenna 334 and processes the transmission to recover the information modulated onto the carrier.
  • the information recovered by the receiver 335 is provided to a receive frame processor 336 , which parses each frame, and provides the midamble 214 ( FIG. 2 ) to the channel processor 344 and the data, control, and reference signals to a receive processor 338 .
  • the receive processor 338 performs the inverse of the processing performed by the transmit processor 380 in the UE 350 .
  • the data and control signals carried by the successfully decoded frames may then be provided to a data sink 339 and the controller/processor, respectively. If some of the frames were unsuccessfully decoded by the receive processor, the controller/processor 340 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.
  • ACK acknowledge
  • the controller/processors 340 and 390 may be used to direct the operation at the node B 310 and the UE 350 , respectively.
  • the controller/processors 340 and 390 may provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions.
  • the computer readable media of memory 392 may store data and software for the UE 350 .
  • the memory 392 of the UE 350 may store a system frame number (SFN) management module 391 which, when executed by the controller/processor 390 , configures the UE 350 for recording a relative system frame number difference between a serving RAT and a target RAT during an IRAT measurement.
  • SFN system frame number
  • SFN System Frame Number
  • CSFB Circuit-Switched Fallback
  • FIG. 4 illustrates coverage of a newly deployed network, such as an LTE network and also coverage of a more established network, such as a TD-SCDMA network.
  • a geographical area 400 may include LTE cells 402 and TD-SCDMA cells 404 .
  • a user equipment (UE) 406 may move from one cell, such as a TD-SCDMA cell 404 , to another cell, such as an LTE cell 402 . The movement of the UE 406 may specify a handover or a cell reselection.
  • Handover from a first radio access technology (RAT) to a second RAT may occur for several reasons.
  • the network may prefer to have the user equipment (UE) use the first RAT as a primary RAT and to use the second RAT for only a specific function, such as for only voice service(s).
  • UE user equipment
  • the handover from the first RAT to the second RAT may be based on measurement reporting.
  • Redirection from one RAT to another RAT commonly occurs, for example, to implement load balancing. Redirection may also be utilized to implement circuit-switched fallback (CSFB) from one RAT, such as Long Term Evolution (LTE) to a second RAT, such as Universal Mobile Telecommunications System (UMTS) frequency division duplex (FDD), UMTS time division duplex (TDD), or GSM.
  • CSFB circuit-switched fallback
  • Circuit-switched fallback is a feature that enables multimode UEs that have, for example, third generation (3G)/second generation (2G) network capabilities in addition to LTE capabilities, to have circuit switched (CS) voice services while being camped on an LTE network.
  • a circuit-switched fallback capable UE may initiate a mobile-originated (MO) circuit-switched (CS) voice call while on LTE. This results in the UE being moved to a circuit-switched capable radio access network (RAN), such as a 3G or 2G network for CS voice call setup.
  • RAN radio access network
  • a circuit-switched fallback capable UE may be paged for a mobile-terminated (MT) voice call while on LTE, resulting in the UE being moved to a 3G or 2G network for circuit-switched voice call setup.
  • MT mobile-terminated
  • Various methods are utilized in attempt to reduce latency that occurs during circuit-switched fallback call (CFSB) setup. For example, system information block (SIB) tunneling and deferred measurement control reading (DMCR) may be introduced to reduce latency for call setup.
  • SIB system information block
  • DMCR deferred measurement control reading
  • the delay related to call setup may increase due to additional signaling on both the LTE and UTRAN sides. A substantial part of the call setup delay results from reading system information on the UTRAN prior to the access.
  • SIB tunneling and DMCR implementations that may be utilized to meet operator indicator specifications for call setup delay.
  • the UE only reads SIBs 1, 3, 5 and 7 prior to accessing the UTRAN cell for CSFB.
  • the other SIBs, including SIB 11, 12 and 19, are not read prior to accessing the UTRAN for CSFB.
  • SIBs e.g., SIBs 11, 12 and 19
  • SIBs 11, 12 and 19 are read again once the UE returns to an idle mode on the UTRAN cell after the circuit-switched call setup has been terminated or the circuit-switched call has ended.
  • all of the TD-SCDMA SIBs are carried in a radio resource control (RRC) release message from the LTE network.
  • RRC radio resource control
  • the UE skips reading all of the SIBs from the TD-SCDMA network.
  • the UE After the UE is redirected to the TD-SCDMA network by the LTE network, and during TD-SCDMA cell acquisition, the UE is only aware of a 5 ms sub-frame boundary. The UE, however, has to find a 20-40 ms transmission time interval (TTI) boundary after the UE is redirected.
  • TTI transmission time interval
  • the UE locates the transmission time interval (TTI) boundary by blindly decoding the broadcast control channel (BCCH) without knowledge of the BCCH boundary.
  • BCCH broadcast control channel
  • aspects of the present disclosure are directed to determining the TTI boundary in a more efficient manner, thereby reducing latency.
  • the network may indicate a SFN relative difference in the radio resource control (RRC) release message from the LTE network.
  • RRC radio resource control
  • the UE can find the TD-SCDMA SFN based on the relative difference between the LTE SFN and TD-SCDMA SFN, and then determine the TTI boundary. This implementation reduces the latency of CSFB to TD-SCDMA setup based on the SIB tunneling implementation.
  • the UE records the relative difference between the TD-SCDMA SFN and the LTE SFN during an IRAT measurement. After the UE is redirected to the TD-SCDMA network, the UE determines the TTI boundary based on its record. In this aspect, the UE skips the blind decoding of the broadcast control channel (BCCH) of a target RAT to read an SFN in order to determine the TTI boundary. This implementation also reduces the latency of CSFB to TD-SCDMA setup based on the SIB tunneling implementation.
  • BCCH broadcast control channel
  • the UE records the absolute SFN of a target RAT. After redirection, the UE determines the TTI boundary based on the recorded absolute SFN. In another aspect, the UE records the absolute SFN and/or relative difference between the TD-SCDMA SFN and the LTE SFN. The UE then determines the TTI boundary based on the recorded absolute SFN and/or the recorded relative SFN difference. The relative difference may be recorded while the UE is camped in the target RAT. Optionally, the relative difference may be recorded during and IRAT measurement.
  • FIG. 5 is a call flow diagram 500 illustrating example communications of a UE 502 between a TD-SCDMA cell 504 and LTE cell 506 .
  • the UE 502 is connected to/camped on the LTE cell 506 and is in an idle or connected mode. While in idle/connected mode, the UE 502 performs IRAT measurements, at time 512 .
  • the UE records the TD-SCDMA SFN relative difference between the TD-SCDMA network and LTE network while performing the IRAT measurements.
  • the UE 502 receives an RRC connection release and is redirected to the TD-SCDMA network.
  • the RRC release message includes the SFN relative difference.
  • the UE 502 then returns to the TD-SCDMA cell 504 and determines the transmission time interval (TTI).
  • TTI transmission time interval
  • the determination is based on the recorded difference.
  • the determination is based on the relative difference signaled in the RRC connection release message.
  • FIG. 6 shows a wireless communication method 600 according to one aspect of the disclosure.
  • a UE records an absolute system frame number (SFN) of a target radio access technology (RAT) and/or records the relative SFN difference between a serving RAT and a target RAT, at block 602 .
  • the UE determines a transmission time interval (TTI) boundary, after redirection, based the recorded absolute SFN and/or on the recorded relative difference, at block 604 .
  • SFN system frame number
  • RAT target radio access technology
  • FIG. 7 is a diagram illustrating an example of a hardware implementation for an apparatus 700 employing a processing system 714 .
  • the processing system 714 may be implemented with a bus architecture, represented generally by the bus 724 .
  • the bus 724 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 714 and the overall design constraints.
  • the bus 724 links together various circuits including one or more processors and/or hardware modules, represented by the processor 722 the modules 702 , 704 , and the non-transitory computer-readable medium 726 .
  • the bus 724 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.
  • the apparatus includes a processing system 714 coupled to a transceiver 730 .
  • the transceiver 730 is coupled to one or more antennas 720 .
  • the transceiver 730 enables communication with various other apparatus over a transmission medium.
  • the processing system 714 includes a processor 722 coupled to a non-transitory computer-readable medium 726 .
  • the processor 722 is responsible for general processing, including the execution of software stored on the computer-readable medium 726 .
  • the software when executed by the processor 722 , causes the processing system 714 to perform the various functions described for any particular apparatus.
  • the computer-readable medium 726 may also be used for storing data that is manipulated by the processor 722 when executing software.
  • the processing system 714 includes a recording module 702 for recording an absolute system frame number and/or recording relative system frame number difference.
  • the processing system 714 includes a determining module 704 for determining a transmission time interval boundary based on the recording.
  • the modules may be software modules running in the processor 722 , resident/stored in the computer-readable medium 726 , one or more hardware modules coupled to the processor 722 , or some combination thereof.
  • the processing system 714 may be a component of the UE 350 and may include the memory 392 , and/or the controller/processor 390 .
  • an apparatus such as a UE is configured for wireless communication including means for recording.
  • the recording means may be the controller/processor 390 , the memory 392 , the SFN management module 391 , recording module 702 , and/or the processing system 714 configured to perform the recording means.
  • the UE is also configured to include means for determining.
  • the determining means may be the controller/processor 390 , the memory 392 , SFN management module 391 , determining module 704 and/or the processing system 714 configured to perform the determining means.
  • the aforementioned means may be a module or any apparatus configured to perform the functions recited by the aforementioned means.
  • LTE Long Term Evolution
  • LTE-A LTE-Advanced
  • CDMA2000 Evolution-Data Optimized
  • UMB Ultra Mobile Broadband
  • IEEE 802.11 Wi-Fi
  • IEEE 802.16 WiMAX
  • IEEE 802.20 Ultra-Wideband
  • Bluetooth Bluetooth
  • the actual telecommunication standard, network architecture, and/or communication standard employed will depend on the specific application and the overall design constraints imposed on the system.
  • processors have been described in connection with various apparatuses and methods. These processors may be implemented using electronic hardware, computer software, or any combination thereof. Whether such processors are implemented as hardware or software will depend upon the particular application and overall design constraints imposed on the system.
  • a processor, any portion of a processor, or any combination of processors presented in this disclosure may be implemented with a microprocessor, microcontroller, digital signal processor (DSP), a field-programmable gate array (FPGA), a programmable logic device (PLD), a state machine, gated logic, discrete hardware circuits, and other suitable processing components configured to perform the various functions described throughout this disclosure.
  • DSP digital signal processor
  • FPGA field-programmable gate array
  • PLD programmable logic device
  • the functionality of a processor, any portion of a processor, or any combination of processors presented in this disclosure may be implemented with software being executed by a microprocessor, microcontroller, DSP, or other suitable platform.
  • Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.
  • the software may reside on a non-transitory computer-readable medium.
  • a computer-readable medium may include, by way of example, memory such as a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., compact disc (CD), digital versatile disc (DVD)), a smart card, a flash memory device (e.g., card, stick, key drive), random access memory (RAM), read only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), a register, or a removable disk.
  • memory is shown separate from the processors in the various aspects presented throughout this disclosure, the memory may be internal to the processors (e.g., cache or register).
  • Computer-readable media may be embodied in a computer-program product.
  • a computer-program product may include a computer-readable medium in packaging materials.
  • “at least one of: a, b, or c” is intended to cover: a; b; c; a and b; a and c; b and c; and a, b and c.
  • All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims.
  • nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. ⁇ 112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
US14/088,018 2013-11-22 2013-11-22 Managing system frame numbers (SFNs) for circuit-switched fallback (CSFB) Expired - Fee Related US9271199B2 (en)

Priority Applications (7)

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US14/088,018 US9271199B2 (en) 2013-11-22 2013-11-22 Managing system frame numbers (SFNs) for circuit-switched fallback (CSFB)
PCT/US2014/062846 WO2015076994A1 (fr) 2013-11-22 2014-10-29 Gestion de numéros de trame système (sfn) pour repli sur commutation de circuits (csfb)
EP14802243.7A EP3072327A1 (fr) 2013-11-22 2014-10-29 Gestion de numéros de trame système (sfn) pour repli sur commutation de circuits (csfb)
CN201480061287.7A CN105706493A (zh) 2013-11-22 2014-10-29 管理系统帧号（sfn）以用于电路交换回退（csfb）
KR1020167015958A KR20160089407A (ko) 2013-11-22 2014-10-29 회선-교환 폴백(csfb)을 위한 시스템 프레임 번호(sfn)들의 관리
JP2016531994A JP2017500784A (ja) 2013-11-22 2014-10-29 回線交換フォールバック（ｃｓｆｂ）のためのシステムフレーム番号（ｓｆｎ）の管理
TW103138222A TWI566558B (zh) 2013-11-22 2014-11-04 管理系統訊框號以用於電路交換回退

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KR20160089407A (ko) 2016-07-27
WO2015076994A1 (fr) 2015-05-28
TWI566558B (zh) 2017-01-11
CN105706493A (zh) 2016-06-22
TW201526583A (zh) 2015-07-01
EP3072327A1 (fr) 2016-09-28
US20150148043A1 (en) 2015-05-28

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