CN106576299B

CN106576299B - Method of wireless communication, user equipment and computer readable medium

Info

Publication number: CN106576299B
Application number: CN201580040239.4A
Authority: CN
Inventors: P·卡迪里; C·S·沙阿; N·V·奇马普迪; P·凯瓦拉姆; 郭霁明
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2014-07-25
Filing date: 2015-07-24
Publication date: 2020-06-16
Anticipated expiration: 2035-07-24
Also published as: WO2016011661A1; WO2016015003A1; CN106576299A; KR20170038792A; JP2017521966A; JP6571159B2; BR112017000680A2; EP3172938A1

Abstract

An apparatus, e.g., a UE, tunes away from a first RAT to a second RAT during active data transfer between the UE and a network device over the first RAT. The data activity transmission is related to one of an uplink data transmission from the UE or a downlink data transmission to the UE, and tuning away starts a timer that affects the data transmission activity. The UE may initiate continuation of uplink data transfer by resetting the timer associated with the UE when tuning back to the first RAT and sending an SR to the network device when resetting the at least one timer. The UE may initiate continuation of downlink data transfer by causing the network device to exit a power save mode upon tuning back to the first RAT, wherein the timer is associated with the network device and defines a period of the power save mode.

Description

Method of wireless communication, user equipment and computer readable medium

Cross reference to related applications

The present application claims the benefit of an application having PCT International application Ser. No. PCT/CN2014/083028 entitled "Method to Optimize LTE Data Performance Through Request application For Single Radio Hybrid tubes Awaydevices" and filed on 7, 25, 2014, which is expressly incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates generally to communication systems, and more particularly to a method for optimizing LTE data performance by a fast or quick scheduling request method for single radio hybrid tune away devices.

Background

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasting. Typical wireless communication systems may employ multiple-access techniques capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access techniques include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

These multiple access techniques have been adopted in various telecommunications standards to provide a common protocol that enables different wireless devices to communicate at the urban, national, regional, and even global levels. One example of an emerging telecommunications standard is Long Term Evolution (LTE). LTE is an enhanced set of Universal Mobile Telecommunications System (UMTS) mobile standards promulgated by the third generation partnership project (3 GPP). LTE is designed to better support mobile broadband internet access via improving spectral efficiency, reducing cost, improving services, leveraging new spectrum, and better integrating with other open standards by using OFDMA on the Downlink (DL), SC-FDMA on the uplink, and multiple-input multiple-output (MIMO) antenna technologies, among others. However, as the demand for mobile broadband access continues to grow, there is a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multiple access techniques and telecommunication standards using these techniques.

Disclosure of Invention

In one aspect of the disclosure, methods, computer program products, and apparatuses are provided. The apparatus, e.g., a UE, tunes away from a first Radio Access Technology (RAT) to a second RAT during data transfer activity between the UE and a network device over the first RAT. The data activity transmission is related to one of an uplink data transmission from the UE or a downlink data transmission to the UE, and tuning away starts a timer that affects the data transmission activity. When the data transfer activity is uplink data, the UE may initiate continuation of uplink data transfer by resetting the timer associated with the UE when tuning back to the first RAT and sending a Scheduling Request (SR) to the network device when resetting the at least one timer. When the data transfer activity is downlink data, the UE may initiate continuation of the downlink data transfer by causing the network device to exit a power save mode when tuning back to the first RAT, wherein the timer is associated with the network device and defines a period of the power save mode.

Drawings

Fig. 1 is a diagram illustrating one example of a network architecture.

Fig. 2 is a diagram illustrating one example of an access network.

Fig. 3 is a diagram showing one example of a DL frame structure in LTE.

Fig. 4 is a diagram showing one example of a UL frame structure in LTE.

Fig. 5 is a diagram illustrating one example of a radio protocol architecture for the user and control planes.

Fig. 6 is a diagram illustrating one example of an evolved node B and user equipment in an access network.

Fig. 7 is a diagram illustrating one exemplary deployment in which multiple wireless networks have overlapping coverage.

Fig. 8 is a call flow diagram involving uplink data transfer activity between a UE and an eNB.

Fig. 9 is a call flow diagram involving downlink data transfer activity between a UE and an eNB.

Fig. 10 is a flow chart of a method of wireless communication.

Fig. 11 is a conceptual data flow diagram illustrating the data flow between different modules/means/components in an exemplary apparatus.

FIG. 12 is a diagram illustrating one example of a hardware implementation of an apparatus using a processing system.

Detailed Description

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations by which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. It should be apparent, however, to one skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Several aspects of a telecommunications system will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

As an example, an element, or any portion of an element, or any combination of elements, may be implemented with a "processing system" that includes one or more processors. Examples of processors include microprocessors, microcontrollers, Digital Signal Processors (DSPs), Field Programmable Gate Arrays (FPGAs), Programmable Logic Devices (PLDs), state machines, gated logic units, discrete hardware circuits, and other suitable hardware configured to perform the various functions described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code segments, program code, programs, subprograms, software modules, 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 other terminology.

Accordingly, in one or more exemplary embodiments, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, the functions may be stored on or encoded in one or more instructions or code on a computer-readable medium. Computer readable media includes computer storage media. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise Random Access Memory (RAM), Read Only Memory (ROM), Electrically Erasable Programmable ROM (EEPROM), compact disk ROM (CD-ROM) or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Combinations of the above should also be included within the scope of computer-readable media.

Fig. 1 is a diagram illustrating an LTE network architecture 100. The LTE network architecture 100 may be referred to as an Evolved Packet System (EPS) 100. The EPS 100 may include one or more User Equipment (UE)102, an evolved UMTS terrestrial radio access network (E-UTRAN)104, an Evolved Packet Core (EPC)110, and operator Internet Protocol (IP) services 122. The EPS may interconnect with other access networks, but for simplicity those entities/interfaces are not shown. As shown, the EPS provides packet switched services, however, as those skilled in the art will recognize, the various concepts presented throughout this disclosure may be extended to networks providing circuit switched services.

The E-UTRAN includes evolved node bs (enbs) 106 and other enbs 108, and may include a Multicast Coordination Entity (MCE) 128. The eNB 106 provides user and control plane protocol terminations toward the UE 102. The eNB 106 may connect to other enbs 108 via a backhaul (e.g., an X2 interface). The MCE 128 allocates time/frequency radio resources for an evolved Multimedia Broadcast Multicast Service (MBMS) (eMBMS) and determines a radio configuration (e.g., a Modulation and Coding Scheme (MCS)) of the eMBMS. MCE 128 may be a separate entity or part of eNB 106. The eNB 106 may also be referred to as a base station, a node B, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a Basic Service Set (BSS), an Extended Service Set (ESS), or some other suitable terminology. eNB 106 provides an access point for UE 102 to EPC 110. Examples of UEs 102 include a cellular phone, a smart phone, a Session Initiation Protocol (SIP) phone, a laptop, a Personal Digital Assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet computer, or any other similar functioning device. UE 102 may also be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a mobile device, a user agent, a mobile client, a client, or some other suitable terminology.

eNB 106 is connected to EPC 110. EPC 110 may include Mobility Management Entity (MME)112, Home Subscriber Server (HSS)120, other MMEs 114, serving gateway 116, Multimedia Broadcast Multicast Service (MBMS) gateway 124, broadcast multicast service center (BM-SC)126, and Packet Data Network (PDN) gateway 118. MME 112 is a control node that handles signaling between UE 102 and EPC 110. In general, the MME 112 provides bearer and connection management. All user IP packets are passed through the serving gateway 116, which serving gateway 116 is itself connected to the PDN gateway 118. The PDN gateway 118 provides IP address allocation for the UE as well as other functions. The PDN gateway 118 and BM-SC 126 are connected to the IP service 122. The IP services 122 may include the internet, intranets, IP Multimedia Subsystem (IMS), PS streaming services (PSs), and/or other IP services. BM-SC 126 may provide functionality for MBMS user service provisioning and delivery. BM-SC 126 may serve as an entry point for content provider MBMS transmissions, may be used to authorize and initiate MBMS bearer services within the PLMN, and may be used to schedule and deliver MBMS transmissions. The MBMS gateway 124 may be used to distribute MBMS traffic to enbs (e.g., 106, 108) belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS-related charging information.

Fig. 2 is a diagram illustrating one example of an access network 200 in an LTE network architecture. In this example, the access network 200 is divided into a plurality of cellular regions (cells) 202. One or more lower power class enbs 208 may have cellular regions 210 that overlap with one or more of cells 202. The lower power class eNB 208 may be a femto cell (e.g., a home eNB (henb)), pico cell, micro cell, or Remote Radio Head (RRH). The macro cell enbs 204 are each assigned a respective cell 202 and are configured to provide an access point to the EPC 110 for all UEs 206 in the cells 202. There is no centralized controller in this example of the access network 200, but a centralized controller may be used in alternative configurations. The eNB 204 is responsible for all radio-related functions including radio bearer control, admission control, mobility control, scheduling, security, and connectivity to the serving gateway 116. An eNB may support one or more (e.g., three) cells (also referred to as sectors). The term "cell" may refer to the smallest coverage area of an eNB and/or an eNB subsystem serving a particular coverage area. Further, the terms "eNB", "base station", and "cell" may be used interchangeably herein.

The modulation and multiple access schemes used by the access network 200 may vary depending on the particular telecommunications standard being deployed. In LTE applications, OFDM is used on the DL and SC-FDMA is used on the UL to support both Frequency Division Duplex (FDD) and Time Division Duplex (TDD). As those skilled in the art will readily recognize from the following detailed description, the various concepts presented herein are well suited for LTE applications. However, these concepts can be easily extended to other telecommunication standards using other modulation and multiple access techniques. By way of example, these concepts may be extended to evolution data optimized (EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interface standards promulgated by the third generation partnership project 2(3GPP2) as part of the CDMA2000 family of standards for providing broadband internet access to mobile stations. These concepts can also be extended to: universal Terrestrial Radio Access (UTRA) using wideband CDMA (W-CDMA) and other variants of CDMA such as TD-SCDMA; global system for mobile communications (GSM) using TDMA; and evolved UTRA (E-UTRA), IEEE 802.11(Wi-Fi), IEEE 802.16(WiMAX), IEEE 802.20, and Flash-OFDM using OFDMA. UTRA, E-UTRA, UMTS, LTE, and GSM are described in documents from the 3GPP organization. CDMA2000 and UMB are described in documents from the 3GPP2 organization. The actual wireless communication standard and multiple access technique used will depend on the particular application and the overall design constraints imposed on the system.

The eNB 204 may have multiple antennas supporting MIMO technology. Using MIMO technology enables the eNB 204 to utilize the spatial domain to support spatial multiplexing, beamforming, and transmit diversity. Spatial multiplexing may be used to transmit different data streams over the same frequency at the same time. The data stream may be sent to a single UE 206 to increase the data rate or to multiple UEs 206 to increase the overall system capacity. This is achieved by spatially precoding each data stream (i.e., applying a scaling of the amplitude and phase) and then transmitting each spatially precoded stream over multiple transmit antennas on the DL. The spatially precoded data streams arrive at the UEs 206 with different spatial signatures, which enables each of the UEs 206 to recover one or more data streams destined for that UE 206. On the UL, each UE 206 transmits a spatially precoded data stream, which enables the eNB 204 to identify the source of each spatially precoded data stream.

Spatial multiplexing is typically used when channel conditions are good. When channel conditions are less favorable, beamforming may be used to focus the transmitted energy in one or more directions. This may be achieved by spatially precoding the data for transmission over multiple antennas. To achieve good coverage at the edges of the cell, single stream beamforming transmission may be used in combination with transmit diversity.

In the following detailed description, various aspects of an access network will be described with reference to a MIMO system supporting OFDM on the DL. OFDM is a spread spectrum technique that modulates data onto multiple subcarriers within an OFDM symbol. The subcarriers are spaced apart at precise frequencies. The spacing provides "orthogonality" that enables the receiver to recover the data from the subcarriers. In the time domain, a guard interval (e.g., a cyclic prefix) may be added to each OFDM symbol to combat inter-OFDM symbol interference. The UL may use SC-FDMA in the form of DFT spread OFDM signal to compensate for high peak-to-average power ratio (PAPR).

Fig. 3 is a diagram 300 showing one example of a DL frame structure in LTE. A frame (10 ms) may be divided into 10 equally sized subframes. Each subframe may include two consecutive slots. The resource grid may be used to represent two slots, each slot comprising one resource block. The resource grid is divided into a plurality of resource elements. In LTE, for a normal cyclic prefix, a resource block contains 12 consecutive subcarriers in the frequency domain and 7 consecutive OFDM symbols in the time domain, for a total of 84 resource elements. For an extended cyclic prefix, a resource block contains 12 consecutive subcarriers in the frequency domain and 6 consecutive OFDM symbols in the time domain, for a total of 72 resource elements. Some of the resource elements indicated as R302, 304 include DL reference signals (DL-RS). The DL-RS includes cell-specific RS (crs) (also sometimes referred to as common RS)302 and UE-specific RS (UE-RS) 304. The UE-RS304 is transmitted only through resource blocks to which a corresponding Physical DL Shared Channel (PDSCH) is mapped. The number of bits carried by each resource element depends on the modulation scheme. Thus, the more resource blocks the UE receives and the higher the modulation scheme, the higher the data rate of the UE.

Fig. 4 is a diagram 400 illustrating one example of a UL frame structure in LTE. The resource blocks available for the UL may be divided into a data interval and a control interval. The control interval may be formed at both edges of the system bandwidth and may have a configurable size. Resource blocks in the control interval may be allocated to the UE for transmission of control information. The data interval may include all resource blocks not included in the control interval. The UL frame structure results in a data interval including contiguous subcarriers, which may allow a single UE to be allocated all of the contiguous subcarriers in the data interval.

The UE may be allocated

resource blocks

410a, 410b in the control interval to send control information to the eNB. The UE may also be allocated

resource blocks

420a, 420b in the data interval to transmit data to the eNB. The UE may transmit control information in a Physical UL Control Channel (PUCCH) through the allocated resource blocks in the control interval. The UE may transmit only data or both data and control information in a Physical UL Shared Channel (PUSCH) through allocated resource blocks in a data interval. The UL transmission may span both slots of a subframe and may hop across frequency.

The set of resource blocks may be used to perform initial system access and to achieve UL synchronization in a Physical Random Access Channel (PRACH) 430. The PRACH 430 carries a random sequence and cannot carry any UL data/signaling. Each random access preamble occupies a bandwidth corresponding to six consecutive resource blocks. The starting frequency is specified by the network. I.e. the transmission of the random access preamble is limited to specific time and frequency resources. There is no frequency hopping for PRACH. PRACH attempts are carried in a single subframe (1 ms) or in a sequence of a few consecutive subframes, and the UE may make only a single PRACH attempt per frame (10 ms).

Fig. 5 is a diagram 500 illustrating one example of a radio protocol architecture for the user and control planes in LTE. The radio protocol architecture for the UE and eNB is shown with three layers: layer 1, layer 2 and layer 3. Layer 1(L1 layer) is the lowest layer and implements various physical layer signal processing functions. The L1 layer will be referred to herein as the physical layer 506. Layer 2(L2 layer) 508 is above the physical layer 506 and is responsible for the link between the UE and the eNB through the physical layer 506.

In the user plane, the L2 layer 508 includes a Medium Access Control (MAC) sublayer 510, a Radio Link Control (RLC) sublayer 512, and a Packet Data Convergence Protocol (PDCP)514 sublayer that are terminated at an eNB on the network side. Although not shown, the UE may have several upper layers above the L2 layer 508, including a network layer (e.g., IP layer) terminated at the PDN gateway 118 on the network side and an application layer terminated at the other end of the connection (e.g., far end UE, server, etc.).

The PDCP sublayer 514 provides multiplexing between different radio bearers and logical channels. The PDCP sublayer 514 also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between enbs. The RLC sublayer 512 provides segmentation and reassembly of upper layer data packets, retransmission of lost data packets, and reordering of data packets to compensate for out-of-order reception due to hybrid automatic repeat request (HARQ). The MAC sublayer 510 provides multiplexing between logical and transport channels. The MAC sublayer 510 is also responsible for allocating various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer 510 is also responsible for HARQ operations.

In the control plane, the radio protocol architecture for the UE and eNB is substantially the same for the physical layer 506 and the L2 layer 508, except that there is no header compression function for the control plane. The control plane also includes a Radio Resource Control (RRC) sublayer 516 in layer 3 (layer L3). The RRC sublayer 516 is responsible for obtaining radio resources (e.g., radio bearers) and configuring the lower layers using RRC signaling between the eNB and the UE.

Fig. 6 is a block diagram of an eNB 610 in an access network in communication with a UE 650. In the DL, upper layer packets from the core network are provided to a controller/processor 675. The controller/processor 675 implements the functionality of the L2 layer. In the DL, the controller/processor 675 provides header compression, ciphering, packet segmentation and reordering, multiplexing between logical and transport channels, and radio resource allocation to the UE 650 based on various priority metrics. The controller/processor 675 is also responsible for HARQ operations, retransmission of lost packets, and signaling to the UE 650.

A Transmit (TX) processor 616 performs various signal processing functions for the L1 layer (i.e., the physical layer). The signal processing functions include coding and interleaving to facilitate Forward Error Correction (FEC) at the UE 650 and 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)). The coded and modulated symbols are then split into parallel streams. Each stream is then mapped to OFDM subcarriers, multiplexed with reference signals (e.g., pilots) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM streams are spatially precoded to produce a plurality of spatial streams. The channel estimates from channel estimator 674 may be used to determine coding and modulation schemes and for spatial processing. The channel estimates may be derived from the reference signals and/or channel condition feedback sent by the UE 650. Each spatial stream may then be provided to a different antenna 620 via a separate transmitter 618 TX. Each transmitter 618TX may modulate an RF carrier with a respective spatial stream for transmission.

At the UE 650, each receiver 654RX receives a signal through its respective antenna 652. Each receiver 654RX recovers information modulated onto an RF carrier and provides the information to a Receive (RX) processor 656. The RX processor 656 performs various signal processing functions at the L1 layer. The RX processor 656 may perform spatial processing on the information to recover any spatial streams destined for the UE 650. If multiple spatial streams are intended for the UE 650, they may be combined into a single OFDM symbol stream by the RX processor 656. The RX processor 656 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier and the reference signal are recovered and demodulated by determining the most likely signal constellation points transmitted by the eNB 610. These soft decisions may be based on channel estimates computed by a channel estimator 658. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the eNB 610 over the physical channel. The data and control signals are then provided to the controller/processor 659.

The controller/processor 659 implements the L2 layer. The controller/processor can be associated with a memory 660 that stores program codes and data. The memory 660 may be referred to as a computer-readable medium. In the UL, the controller/processor 659 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the core network. The upper layer packets are then provided to a data sink 662, the data sink 662 representing all protocol layers above the L2 layer. Various control signals may also be provided to a data sink 662 for processing by L3. The controller/processor 659 is also responsible for error detection using Acknowledgement (ACK) and/or Negative Acknowledgement (NACK) protocols to support HARQ operations.

In the UL, a data source 667 is used to provide upper layer packets to the controller/processor 659. The data source 667 represents all protocol layers above the L2 layer. Similar to the functionality described in connection with the DL transmission by the eNB 610, the controller/processor 659 implements the L2 layer for the user plane and the control plane by providing header compression, ciphering, packet segmentation and reordering, and multiplexing between logical and transport channels based on radio resource allocations made by the eNB 610. The controller/processor 659 is also responsible for HARQ operations, retransmission of lost packets, and signaling to the eNB 610.

Channel estimates, derived by a channel estimator 658 from a reference signal or feedback transmitted by the eNB 610, may be used by the TX processor 668 to select the appropriate coding and modulation schemes and to facilitate spatial processing. The spatial streams generated by the TX processor 668 may be provided to different antennas 652 via separate transmitters 654 TX. Each transmitter 654TX may modulate an RF carrier with a respective spatial stream for transmission.

UL transmissions are processed at the eNB 610 in a manner similar to that described in connection with receiver functionality at the UE 640. Each receiver 618RX receives a signal through its respective antenna 620. Each receiver 618RX recovers information modulated onto an RF carrier and provides the information to an RX processor 670. RX processor 670 may implement the L1 layer.

The controller/processor 675 implements the L2 layer. The controller/processor 675 can be associated with a memory 676 that stores program codes and data. The memory 676 may be referred to as a computer-readable medium. In the UL, the controller/processor 675 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the UE 650. Upper layer packets from the controller/processor 675 may be provided to the core network. The controller/processor 675 is also responsible for error detection using ACK and/or NACK protocols to support HARQ operations.

Specific techniques have been designed to provide wireless device operating modes that comply with requirements established for operation on specific frequency bands of a Radio Access Network (RAN). One such technique involves a wireless device receiving voice services from a legacy network (e.g., CDMA 20001 x or simply a "1 x" network) that provides services that geographically overlap with the services of an enhanced network (e.g., long term evolution — LTE network).

In a network supporting both LTE and CDMA, it may be necessary for the UE chipset to support both LTE and CDMA 1 x. There may be two system architectures to support monitoring 1x while operating in LTE. The first architecture may have two separate Radio Frequency (RF) chains, one for LTE and the other for 1 x. The architecture may allow for decoding of 1x voice pages in parallel while an LTE data call is active. This architecture/algorithm is commonly referred to as SVLTE (simultaneous voice and LTE). From high-pass^TMMSM8960^TMThe chipset uses this architecture.

Another architecture may have only one RF chain. The RF chain may have to be shared between LTE and 1x under the constraint that LTE and CDMA technologies may not be active at the same time. To monitor 1x paging, the UE may have to tune away from LTE periodically while the LTE data call is active. While one RF chain architecture improves battery consumption, saves board area and bill of material (BOM), problems may arise when a UE has to periodically monitor 1x voice paging while an LTE data call is active. During RF tuning to 1x time, the LTE call is dropped or essentially dropped, and this may result in disruption of LTE UE functionality that may not be desired by the network.

Fig. 7 illustrates one exemplary deployment in which multiple wireless networks have overlapping coverage. An evolved universal terrestrial radio access network (E-UTRAN)720 may support LTE and may include a plurality of evolved node bs (enbs) 722 and other network entities that may support wireless communication for User Equipment (UE). Each eNB may provide communication coverage for a particular geographic area. The term "cell" may refer to a coverage area of an eNB and/or an eNB subsystem serving the coverage area. A serving gateway (S-GW)724 may communicate with the E-UTRAN 720 and may perform various functions such as packet routing and forwarding, mobility anchoring, packet buffering, initiation of network-triggered services, and so forth. A Mobility Management Entity (MME)726 may communicate with E-UTRAN 720 and serving gateway 724 and may perform various functions such as mobility management, bearer management, distribution of paging messages, security control, authentication, gateway selection, and the like. The publicly available names are "Evolved Universal Radio Access (E-UTRA) and Evolved Universal Radio Access Network (E-UTRAN); network entities in LTE are described in 3GPP TS 36.300 for overhall description ".

Radio Access Network (RAN)730 may support 1xRTT and may include a plurality of base stations 732 and other network entities that may support wireless communications for the UE. A Mobile Switching Center (MSC)734 may communicate with RAN 730 and may support voice services, route circuit-switched calls, and perform mobility management for UEs located within an area served by MSC 734. An interworking function (IWF)740 may facilitate communications between the MME 726 and the MSC 734. Network entities in 1xRTT are described in publicly available documents from 3GPP 2.

The E-UTRAN 720, serving gateway 724, and MME 726 may be part of the LTE network 702. RAN 730 and MSC734 may be part of a 1xRTT network 704. For simplicity, fig. 7 shows only some of the network entities in an LTE network and a 1xRTT network. LTE and 1xRTT networks may also include other network entities that may support various functions and services.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular RAT and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, air interface, etc. A frequency may also be referred to as a carrier, a frequency channel, etc. Each frequency may support a single RAT in a given geographic area to avoid interference between wireless networks of different RATs.

The UE710 may be fixed or mobile and may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, etc. The UE710 may be a cellular telephone, a Personal Digital Assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless telephone, a Wireless Local Loop (WLL) station, or the like.

At power up, the UE710 may search for a wireless network from which it may receive communication services. If more than one wireless network is detected, the wireless network with the highest priority may be selected to provide service to the UE710 and may be referred to as a serving network. The UE710 may perform registration with the serving network if necessary. The UE710 may then operate in a connected mode to actively communicate with the serving network. Alternatively, if active communication is not needed by the UE710, the UE710 may operate in idle mode and camp on the serving network.

The UE710, while in idle mode, may be located within coverage of cells of multiple frequencies and/or multiple RATs. For LTE, the UE710 may select a frequency and RAT to camp on based on the priority list. The priority list may include a set of frequencies, a RAT associated with each frequency, and a priority assigned to each frequency. For example, the priority list may include three frequencies X, Y and Z. Frequency X may be used for LTE and may have the highest priority, frequency Y may be used for 1xRTT and may have the lowest priority, and frequency Z may also be used for 1xRTT and may have a medium priority. In general, the priority list may include any number of frequencies for any set of RATs and may be UE location specific. The UE710 may be configured to prefer LTE when available by defining a priority list with LTE frequencies at the highest priority and frequencies for other RATs at lower priorities, e.g., as given by the example above.

The UE710 may operate in idle mode as follows. The UE710 may identify all frequencies/RATs on which it can find a "suitable" cell in the normal scenario or an "acceptable" cell in the emergency scenario, where "suitable" and "acceptable" are specified in the LTE standard. The UE710 may then camp on the frequency/RAT with the highest priority among all identified frequencies/RATs. The UE710 may remain camped on the frequency/RAT until either (i) the frequency/RAT is no longer available at a predetermined threshold or (ii) another frequency/RAT with a higher priority reaches the threshold. Under the publicly available name "Evolved Universal Radio Access (E-UTRA); this operational behavior of the UE710 in idle mode is described in 3GPP TS 36.304 of User Equipment (UE) procedure in idle mode ".

The UE710, while in idle mode, may be capable of receiving Packet Switched (PS) data services from the LTE network 702 and may be camped on the LTE network. The LTE network 702 may have limited or no support for voice over internet protocol (VoIP), which may often be the case for early deployments of LTE networks. Due to limited VoIP support, the UE710 may be transferred to another wireless network of another RAT for a voice call. This transition may be referred to as a Circuit Switched (CS) fallback. The UE710 may be transferred to a RAT that may support voice services, such as 1xRTT, WCDMA, GSM, etc. For call origination with CS fallback, the UE710 may initially become connected to a wireless network of a source RAT (e.g., LTE) that may not support voice services. The UE may make a voice call with the wireless network and may be transferred to another wireless network of the target RAT that may support the voice call through higher layer signaling. Higher layer signaling for transferring the UE to the target RAT may be for various procedures, e.g., connection release with redirection, PS handover, etc.

Aspects of the present disclosure provide techniques that may help improve performance when resuming operation in a first Radio Access Network (RAN) after aborting operation (e.g., to perform operations in a second RAN). In particular, the techniques presented herein may be particularly suited for UEs that share a single RF chain between networks.

As noted above, in some cases, it may be desirable for a device to operate with a single RF chain (e.g., to reduce cost, reduce size, and limit power consumption). In such a case, a single RF chain may be shared between multiple RAT networks (e.g., an LTE network for Packet Switched (PS) services and a 1x network for Circuit Switched (CS) services). Thus, it may not be possible for LTE and 1x technologies (e.g., CDMA, GSM, or UMTS) to be active at the same time.

Problems may arise when the UE regularly monitors 1x voice paging while the LTE data call is active. During the time when the RF is tuned to 1x, the LTE call may be essentially dropped and this may result in interruption of LTE UE functionality that may not be desired by the network. This can have a number of adverse effects on LTE calls when resuming from suspended operations. This architecture/algorithm for devices operating with one RF chain is commonly referred to as suspended LTE.

To minimize the impact on LTE calls upon restart from suspended operations, certain aspects of the present disclosure provide techniques for effecting a change in behavior at the UE upon restart after tuning away to a 1x network. The present disclosure relates to enhancing LTE data throughput and latency performance of hybrid tune away devices (single radio devices) through a fast or fast Scheduling Request (SR) mechanism after a UE tunes back to an LTE system.

As noted above, the LTE hybrid tune away device may tune away to other legacy voice service technologies, such as 1x RTT, GSM, TD-SCDMA, or other 3G technologies. As the UE tunes away to other technologies for monitoring any incoming pages or overhead message updates, the UE misses any data scheduled by the LTE eNB during the time of the tune away. Further significant delays in LTE UL and DL data scheduling after the UE tunes back to the LTE system may occur if a Continuous Discontinuous Reception (CDRX) or Discontinuous Transmission (DTX) state is entered during tune away, or if a UE Buffer Status Report (BSR) retransmission timer is running. The present disclosure provides UE-based rapid SR enhancement after tuning back to the LTE system in order to quickly resume LTE data services and improve LTE data throughput performance.

Fig. 8 is a call flow diagram 800 relating to uplink data transfer activity between a UE802 and an eNB 804 according to an aspect of the disclosure. When the UE802 has UL data to be transmitted over a first RAT (e.g., LTE), the UE transmits a Buffer Status Report (BSR) to the eNB 804. The eNB 804 may receive the BSR and send an UL grant to the UE. However, if the UE802 has tuned 806 away from the LTE system, the UE802 may miss the grant. For example, assume that the UE is doing UL active data transfer over an LTE system and sends a BSR to the eNB to indicate that the UE has data in its UL data buffer. When a BSR is transmitted and then the UE tunes away to another RAT, the UE may miss a PUSCH grant from the eNB due to the tuning away. As a result of missing the UL grant, the UE802 MAC starts a "retxsrb-timer" 808. During the time the UE is tuned away, the retxsbsr-timer continues to run on the LTE stack. A typical setting for this timer is 320 milliseconds. However, the setting may be changed based on the network configuration. Typical tune away times are variable and may be in the range of 20-160 milliseconds. The tune away period may be based on UE operation when the UE tunes away to another RAT. After the UE tunes back to the LTE system 810, data will be pending in the UE UL buffer since the UE misses the PUSCH UL grant during tune away. In current UE operation, the UE will send another BSR when the retxsrb-timer expires. The delay in time between the time the UE tunes back to the LTE system and the time the retxsrb-timer expires results in a significant delay of the UL data packets and hence in a loss of UL throughput.

With continued reference to fig. 8, to address the aforementioned latency issue, in one aspect of the present disclosure, upon tuning back to the LTE system, the UE determines whether there is a buffered BSR pending. In other words, the UE determines whether it has sent a BSR before tuning away, and whether the data in the UL data transfer buffer is still present in the buffer after the UE tunes back to the LTE system. If the buffered BSR is pending, the UE MAC immediately and automatically resets the "retxBSR-timer" 812 and immediately triggers or sends an SR to the eNB to request UL PUSCH resources. This immediate SR may be referred to as a "fast SR" or "fast SR". Upon receiving a UL grant sent by the eNB in response to the prompt SR, the UE may send buffered UL data according to the resources indicated in the grant. Accordingly, the UE can transmit data in a more time efficient manner without having to wait for the retxsbr-timer to expire.

In another scenario related to UL data transmission, there may be bursts of UL data transmission in progress, in which case the UE UL buffer data may not be available at all times. Assume that there is some data in the UE UL data buffer that causes the UE to send an SR and receive a UL PUSCH grant from the eNB. Further assume that the UE transmitted UL PUSCH using RV0 and failed to receive DL PHICH ACK/NACK from eNB due to UE tune away. If the eNB fails to decode the PUSCH data correctly, it may send PHICH NACK. Assuming UL adaptive retransmission, the eNB may allocate a new UL grant for PUSCH retransmission. However, this reallocation will be missed by the UE as it is tuned away. After the UE tunes back to the LTE system, if the UE blindly reuses the same PUSCH resources received by the UE before tuning away to transmit UL data, the data may not be successfully decoded by the eNB if the UE has used UL non-adaptive HARQ resources for PUSCH retransmission. Furthermore, if the same resources previously allocated to the tuned-away first UE are subsequently allocated by the eNB to the second UE, the blind reuse of the same PUSCH resources for retransmission by the first UE after it tunes back to the LTE system will result in interference with the second UE that has been allocated the same resources. This interference results in an overall loss of throughput for both the first and second UEs.

The aforementioned problems of failure to decode and interference can be solved in the same manner as presented in relation to fig. 8. The UE may avoid blindly reusing the previously allocated UL grant resources by: the retx-BSR-timer is automatically and immediately reset upon tuning back to the LTE system and SR is immediately transmitted to obtain UL grant even if the retx-BSR-timer is not running in this scenario (since PUSCH grant is allocated to the UE before tuning away) and the UE is not using the old PUSCH grant resources for retransmission purposes but is about to send a fast SR request for the new PUSCH grant resources.

Fig. 9 is a call flow diagram 900 relating to downlink data transfer activity between a UE902 and an eNB904 according to an aspect of the disclosure. DL data transfer between the UE902 and a network device 904 (e.g., an eNB) is ongoing over the LTE system. The UE902 tunes away 906 to another RAT 904 during DL data transfer. When the UE902 tunes away to another RAT, the UE will miss scheduled DL data, e.g., PDSCH data. Because the UE902 misses the DL data, the UE will not send UL HARQ ACK/NACK regarding reception of the DL data. Since there is no UL HARQ ACK/NACK from the UE902, the eNB904 may determine that the UE is no longer responding to any DL data and may enter the power save mode 908 with respect to the UE. For example, eNB904 may enter CDRX state or DTX state after expiration of a drx inactivity timer. Once in one of these states, the eNB904 may attempt to schedule DL data to the UE during the on-duration of the power saving mode period (e.g., CDRX period). Assume that the eNB904 enters a long DRX cycle (typically 320 ms) after the short CDRX cycle (typically 40 ms) has ended and at the same time the UE reverts 910 back to the LTE system. In this case, the eNB schedules the data when the long CDRX period expires even after the UE tunes back to the LTE system. This results in LTE DL throughput degradation and increased latency for data transfer.

With continued reference to fig. 9, to address the aforementioned latency issue, in one aspect of the disclosure, after the UE tunes 910 back to the LTE system, the UE determines whether to send a rapid SR based on the presence of pending UL data in the UE data buffer or criteria related to the reception of the DL before the UE tunes away. If UL data is pending in the UE data buffer, the UE automatically and immediately initiates a BSR transmission followed by a fast SR, as described above with reference to fig. 8. If there is no pending UE UL buffer data, the UE determines whether the DL data criterion is satisfied. In one configuration, the UE may determine whether the amount of DL data received over a period of "x" milliseconds before the UE tunes away 906 is above a threshold amount of "y" bits. For example, the criterion may be considered satisfied if the size of the DL transport block received by the UE902 during the time period 200 milliseconds is greater than or equal to 72 bits. If the criteria are met, the UE902 sends a fast SR. In response to the prompt SR, the eNB904 provides the UE with an UL PUSCH grant. In this case, the UE MAC layer may send padding data, e.g., all zeros, in a given MAC transport block, since the UE does not have pending UL data in any data buffer or signaling information to send. The SR transmitted by the UE902 causes the eNB904 to exit the power saving mode 912 (e.g., DTX state or CDRX state) and begin DL PDSCH data scheduling.

The SR process involved in the foregoing implementation still adheres to "SR-prohibit-timer" and "dsr-TransMax" (if configured by the network side). If the SR-prohibit timer value is greater than 1 and still running after the UE tunes back to the LTE system, the UE may reset the timer and send a fast SR at the next available immediate SR transmission opportunity.

Conditions other than the examples described above may trigger the rapid SR mechanism. For example, in a case where the UE enters a power saving state (e.g., CDRX) while camped on a first RAT and then tunes away to a second RAT, the UE will not receive any DL data scheduled by the eNB of the first RAT during the on period of the CDRX cycle. Furthermore, if the duration of the UE tune away is long, e.g., one second or more, the UE may miss all DL data scheduling attempts attempted by the eNB. According to an embodiment of prompt SR triggering, the UE may trigger a prompt SR when tuning back to the first RAT even if there is no UL/DL data activity seen by the UE. The UE may determine that there is no UL/DL data activity based on the absence of active PDSCH or PUSCH data transmission activity prior to the UE tuning away. This embodiment differs from the embodiment of fig. 8, where the UE looks for UL data in its buffer before sending the fast SR, and the embodiment of fig. 9, where the UE looks for a DL grant received before tuning away before sending the fast SR. In this embodiment, the UE and eNB will run CDRX timers. After a tune back by the UE, these CDRX timers are reset/stopped according to the current standard and the UE sends a prompt SR.

Fig. 10 is a flow chart 1000 of a method of wireless communication. The method may be performed by a UE (e.g., UE802, 902, apparatus 1102/1102'). At step 1002, the UE tunes away from a first RAT (e.g., LTE) to a second RAT (e.g., 1xRTT or other RAT). The tune away occurs during a data transfer activity (e.g., one of a UL data transfer or a DL data transfer) between the UE and a network device (e.g., an eNB) over the first RAT, and at least one timer affecting the data transfer activity is started. The data transfer activity may relate to one of an uplink data transfer from the UE or a downlink data transfer to the UE.

In one implementation, the data transmission activity may be related to uplink data transmission from the UE. Referring to fig. 8, the activity may involve the UE802 transmitting a BSR to the eNB 804 for the purpose of receiving a UL scheduling grant. Accordingly, "data transfer activity" does not necessarily involve actual, active data transfer between the UE802 and the network device 804. Such data transfer activity may simply involve the sending of a message (e.g., a BSR) that facilitates the actual data transfer. In the case of uplink data transfer activity, at least one timer is associated with the UE802 and may define a time during which the UE refrains from requesting data transfer. Accordingly, the timer affects data transfer. For example, if the UE802 tunes away after transmitting a BSR, the UE starts a timer during which the UE does not transmit another BSR. The timer may correspond to a BSR timer of the UE 802. With continued reference to fig. 8, initiating continuation of the data transfer activity may include: the UE802 resets the at least one timer and, upon resetting the at least one timer, transmits an SR to the network device 804.

In this scenario, i.e., when the data transfer activity relates to an uplink data transfer, at step 1004 the UE802 initiates continuation of the uplink data transfer upon tuning back to the first RAT by: resetting at least one timer, wherein the timer is associated with the UE; and immediately transmitting the SR to the network device 804 upon resetting the at least one timer. Since the UE sends a BSR requesting an uplink grant due to the presence of uplink data in the UE buffer, the UE802 inherently knows that the data transfer when tuning away from the first RAT is uplink.

In another implementation, the data transfer activity may relate to a downlink data transfer to the UE. Referring to fig. 9, the activity may involve the reception of a DL scheduling grant from the eNB by the UE902 followed by the reception of DL data from the eNB 904. Accordingly, in this case, the "data transfer activity" relates to an actual and active DL data transfer, and the UE902 tunes away during this active downlink data transfer. The at least one timer that affects data transfer activity defines a period of a power saving mode that the eNB904 may enter after determining that the UE902 is not responding to a DL data transfer, wherein such lack of response from the UE is due to a tune away by the UE. The period has an off duration during which the network device 904 avoids sending downlink data. The timer may be a DRX or CDRX timer of the network device. With continued reference to fig. 9, initiating continuation of the data transfer activity includes: the network device 904 is caused to exit the power saving mode, for example, by sending an SR to the network device.

In this scenario, i.e. when the data transfer activity relates to a downlink data transfer, at step 1006 the UE902 initiates continuation of the downlink data transfer by causing the network device 904 to exit the power saving mode when tuning back to the first RAT, wherein at least one timer is associated with the network device and defines a period of the power saving mode. Because the UE902 received the downlink grant from the eNB904 and is receiving DL data at tune away, the UE902 inherently knows that the data transmission at tune away from the first RAT is downlink.

Fig. 11 is a conceptual data flow diagram 1100 illustrating the data flow between different modules/means/components in an exemplary apparatus 1102. The apparatus may be a UE. The apparatus includes a tune away/back module 1104, an initiation module 1106, and a transmission module 1108.

The tune away/tune back module 1104 tunes away from the first RAT to the second RAT during data transfer activity over the first RAT between the UE and the network device 1150. The tune away starts at least one timer that affects data transfer activity. In case of uplink data transmission, a timer is included in the UE 1102. In the case of downlink data transmission, a timer is included in network device 1150.

The initiation module 1106 initiates continuation of the data transfer activity immediately upon the UE tuning back to the first RAT. In case of uplink data transmission, the initiating module 1106 resets a timer included in the UE and transmits an SR to the network device 1150 through the transmitting module 1108. In the case of downlink data, the initiating module resets a timer included in the network device by sending an SR to the network device via the transmitting module 1108.

The apparatus 1102 may include additional modules that perform each of the aforementioned steps of the algorithms in the call flow diagrams of fig. 8 and 9 and the flow diagram of fig. 10. Accordingly, each of the steps in the aforementioned call flow diagrams of fig. 8 and 9 and the flow diagram of fig. 10 may be performed by one module, and an apparatus may include one or more of those modules. A module may be one or more hardware components specifically configured to perform the recited process/algorithm, implemented by a processor configured to perform the recited process/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

Fig. 12 is a diagram 1200 illustrating one example of a hardware implementation of an apparatus 1102' using a processing system 1214. The processing system 1214 may be implemented with a bus architecture, represented generally by the bus 1224. The bus 1224 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 1214 and the overall design constraints. The bus 1224 links together various circuits including one or more processors and/or hardware modules, represented by the processor 1204, the

modules

1104, 1106, 1108, and the computer-readable medium/memory 1206. The bus 1224 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 processing system 1214 may be coupled to a transceiver 1210. The transceiver 1210 is coupled to one or more antennas 1220. The transceiver 1210 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 1210 receives a signal from the one or more antennas 1220, extracts information from the received signal, and provides the extracted information to the processing system 1214. Additionally, the transceiver 1210 receives information from the processing system 1214 (and in particular, from the transmission module 1108') and, based on the received information, generates a signal to be applied to the one or more antennas 1220. The processing system 1214 includes a processor 1204 coupled to a computer-readable medium/memory 1206. The processor 1204 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 1206. The software, when executed by the processor 1204, causes the processing system 1214 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 1206 may also be used for storing data that is manipulated by the processor 1204 when executing software. The processing system also includes at least one of the

modules

1104, 1106, and 1108. The modules may be software modules running in the processor 1204, resident/stored in the computer readable medium/memory 1206, one or more hardware modules coupled to the processor 1204, or some combination thereof. The processing system 1214 may be a component of the UE 650 and may include the memory 660 and/or at least one of the TX processor 668, the RX processor 656, and the controller/processor 659.

In one configuration, the means for wireless communicating 1102/1102' includes means for tuning away 1104 from the first RAT to the second RAT during a data transfer activity between the UE and the network device over the first RAT, wherein the data activity transfer relates to one of an uplink data transfer from the UE or a downlink data transfer to the UE, and the tuning away starts at least one timer affecting the data transfer activity. The apparatus 1102/1102' for wireless communication further includes means for initiating 1106 continuation of the uplink data transfer by resetting the at least one timer when tuning back to the first RAT and sending an SR to the network device when the at least one timer is reset, wherein the timer is associated with the UE. The means for wireless communicating 1102/1102' further includes means for initiating 1106 continuation of the downlink data transfer by causing the network device to exit the power save mode upon tuning back to the first RAT, wherein at least one timer is associated with the network device and defines a period of the power save mode. The means 1102/1102' for wireless communication may further include means for determining 1204, prior to initiating continuation of the downlink data transfer, whether criteria related to downlink data activity prior to the UE tuning away are satisfied.

The aforementioned means may be one or more of the aforementioned modules of the processing system 1214 of the apparatus 1102 and/or the apparatus 1102' configured to perform the functions recited by the aforementioned means. As described supra, the processing system 1214 may include the TX processor 668, the RX processor 656, and the controller/processor 659. Thus, in one configuration, the aforementioned means may be the TX processor 668, the RX processor 656, and the controller/processor 659 configured to perform the functions recited by the aforementioned means.

In another configuration, a method of wireless communication of a UE includes: entering a power save mode while camped on a first RAT, the power save mode having an on duration during which the UE transmits and/or receives data over the first RAT; tune away from a first RAT to a second RAT, wherein the tune away affects data reception and/or transmission between the UE and the first RAT during an on duration; and initiating a continuation of data reception and/or transmission between the UE and the first RAT immediately upon tuning back to the first RAT.

Similarly, a UE for wireless communication includes: means for entering a power save mode while camped on one RAT, the power save mode having an on duration during which the UE transmits and/or receives data over a first RAT; means for tuning away from a first RAT to a second RAT, wherein the tuning away affects data reception and/or transmission between the UE and the first RAT during an on duration; and means for initiating a continuation of data reception and/or transmission between the UE and the first RAT immediately upon tuning back to the first RAT.

Similarly, a UE for wireless communication includes a memory and at least one processor coupled to the memory. The processor is configured to perform the following operations: causing the UE to enter a power save mode while camped on the first RAT, the power save mode having an on duration during which the UE transmits and/or receives data over the first RAT; tune away from a first RAT to a second RAT, wherein the tune away affects data reception and/or transmission between the UE and the first RAT during an on duration; and initiating a continuation of data reception and/or transmission between the UE and the first RAT immediately upon tuning back to the first RAT.

Similarly, a computer-readable medium of a UE includes code that, when executed on at least one processor, causes the UE to: entering a power save mode while camped on a first RAT, the power save mode having an on duration during which the UE transmits and/or receives data over the first RAT; tune away from a first RAT to a second RAT, wherein the tune away affects data reception and/or transmission between the UE and the first RAT during an on duration; and initiating a continuation of data reception and/or transmission between the UE and the first RAT immediately upon tuning back to the first RAT.

It should be understood that the specific order or hierarchy of steps in the processes/flow diagrams disclosed is an illustration of exemplary approaches. It should be understood that the specific order or hierarchy of steps in the processes/flow diagrams may be rearranged based on design preferences. Further, some steps may be combined or omitted. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more. The term "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects. The term "some" means one or more unless specifically indicated otherwise. Combinations such as "A, B or at least one of C", "at least one of A, B and C", and "A, B, C or any combination thereof" include any combination of A, B and/or C, and may include a plurality of a, B, or C. In particular, a combination such as "at least one of A, B or C", "at least one of A, B and C", and "A, B, C, or any combination thereof" may be a only, B only, C, A and B, A and C, B and C only, or a and B and C, wherein any such combination may contain one member or more members of A, B or 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. Moreover, 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 should be read as indicating a function of a device unless the element is explicitly recited using the phrase "unit for … …".

Claims

1. A method of wireless communication of a user equipment, UE, comprising:

tuning away from a first radio access technology, RAT, to a second RAT during a data transfer activity between the UE and a network device over the first RAT, wherein the data transfer activity relates to one of an uplink data transfer or a downlink data transfer, and tuning away starts at least one timer that affects the data transfer activity; and

upon tuning back to the first RAT, initiate continuation of uplink data transmission by resetting the at least one timer and transmitting a Scheduling Request (SR) to the network device upon resetting the at least one timer, wherein the at least one timer is associated with the UE and defines a time during which the UE refrains from requesting data transmission; or

Initiating continuation of downlink data transfer by causing the network device to exit power save mode upon tuning back to the first RAT, and determining whether a criterion related to downlink data activity prior to the UE tuning away is satisfied before initiating continuation of downlink data transfer, wherein the at least one timer is associated with the network device and defines a periodicity of the power save mode.

2. The method of claim 1, wherein the at least one timer corresponds to a Buffer Status Report (BSR) timer of the UE.

3. The method of claim 1, wherein the period of the power saving mode comprises an off duration during which the network device refrains from transmitting downlink data.

4. The method of claim 3, wherein the at least one timer corresponds to a Discontinuous Reception (DRX) timer of the network device.

5. The method of claim 1, wherein causing the network device to exit the power saving mode comprises: transmitting a Scheduling Request (SR) to the network device.

6. The method of claim 1, wherein the criteria comprises a measurement of a size of downlink data received by the UE during a time period prior to the UE tuning away.

7. A user equipment, UE, for wireless communication, comprising:

means for tuning away from a first radio access technology, RAT, to a second RAT during a data transfer activity between the UE and a network device, wherein the data transfer activity relates to one of an uplink data transfer or a downlink data transfer, and tuning away starts at least one timer that affects the data transfer activity;

means for initiating continuation of uplink data transmission by resetting the at least one timer and sending a Scheduling Request (SR) to the network device when the at least one timer is reset upon tuning back to the first RAT, wherein the at least one timer is associated with the UE and defines a time during which the UE refrains from requesting data transmission;

means for initiating continuation of downlink data transfer by causing the network device to exit a power save mode upon tuning back to the first RAT, wherein the at least one timer is associated with the network device and defines a period of the power save mode; and

means for determining whether a criterion related to downlink data activity prior to the UE tuning away is satisfied before initiating continuation of the downlink data transfer.

8. The UE of claim 7, wherein the at least one timer corresponds to a Buffer Status Report (BSR) timer of the UE.

9. The UE of claim 7, wherein the period of the power saving mode comprises an off duration during which the network device refrains from transmitting downlink data.

10. The UE of claim 9, wherein the at least one timer corresponds to a Discontinuous Reception (DRX) timer of the network device.

11. The UE of claim 7, wherein causing the network device to exit the power save mode comprises: transmitting a Scheduling Request (SR) to the network device.

12. The UE of claim 7, wherein the criteria comprises a measurement of a size of downlink data received by the UE during a time period prior to the UE tuning away.

13. A user equipment, UE, for wireless communication, comprising:

a memory; and

at least one processor coupled to the memory and configured to:

tuning away from a first radio access technology, RAT, to a second RAT during a data transfer activity between the UE and a network device over the first RAT, wherein the data transfer activity relates to one of an uplink data transfer or a downlink data transfer, and tuning away starts at least one timer that affects the data transfer activity;

upon tuning back to the first RAT, initiate continuation of uplink data transmission by resetting the at least one timer and transmitting a Scheduling Request (SR) to the network device upon resetting the at least one timer, wherein the at least one timer is associated with the UE and defines a time during which the UE refrains from requesting data transmission;

initiating continuation of downlink data transfer by causing the network device to exit a power save mode upon tuning back to the first RAT, wherein the at least one timer is associated with the network device and defines a period of the power save mode; and

determining whether a criterion related to downlink data activity prior to the UE tuning away is satisfied before initiating continuation of the downlink data transfer.

14. The UE of claim 13, wherein the at least one timer corresponds to a Buffer Status Report (BSR) timer of the UE.

15. The UE of claim 13, wherein the period of the power saving mode comprises an off duration during which the network device refrains from transmitting downlink data.

16. The UE of claim 15, wherein the at least one timer corresponds to a Discontinuous Reception (DRX) timer of the network device.

17. The UE of claim 13, wherein causing the network device to exit the power save mode comprises: transmitting a Scheduling Request (SR) to the network device.

18. The UE of claim 13, wherein the criteria comprises a measurement of a size of downlink data received by the UE during a time period prior to the UE tuning away.

19. A computer-readable medium storing computer-executable code for wireless communications by a user equipment, UE, which, when executed by at least one processor, causes the UE to:

20. The computer-readable medium of claim 19, wherein the at least one timer corresponds to a Buffer Status Report (BSR) timer of the UE.

21. The computer-readable medium of claim 19, wherein the period of the power saving mode comprises an off duration during which the network device refrains from transmitting downlink data.

22. The computer-readable medium of claim 21, wherein the at least one timer corresponds to a Discontinuous Reception (DRX) timer of the network device.

23. The computer-readable medium of claim 19, wherein code for causing the network device to exit the power save mode comprises: code for transmitting a Scheduling Request (SR) to the network device.