WO2017140082A1

WO2017140082A1 - System and methods for improving performance during radio resource control (rrc) connected state on wireless communication device supporting concurrent radio access technologies

Info

Publication number: WO2017140082A1
Application number: PCT/CN2016/089367
Authority: WO
Inventors: Ling Xie; Peng Wu; Jiming Guo; Zhongsheng LI; Reza Shahidi; Chintan Shirish SHAH
Original assignee: Qualcomm Incorporated
Priority date: 2016-02-18
Filing date: 2016-07-08
Publication date: 2017-08-24
Also published as: WO2017139943A1

Abstract

Methods and devices address managing uplink resource grants on a wireless communication device configured with a radio frequency (RF) resource supporting at least a first and second radio access technology (RAT). When a first protocol stack is in a radio resource control (RRC) -connected state in a network associated with the first RAT, a tune-away event on the first protocol stack may be detected in which the RF resource tunes from the network associated with the first RAT to a network associated with the second RAT, and the RF resource tunes back to the network associated with the first RAT after a tune-away duration. A first scheduling request procedure may be triggered on the first protocol stack, and a protection window mechanism may be implemented during a time window following the tune-away duration.

Description

[Title established by the ISA under Rule 37.2] SYSTEM AND METHODS FOR IMPROVING PERFORMANCE DURING RADIO RESOURCE CONTROL (RRC) CONNECTED STATE ON WIRELESS COMMUNICATION DEVICE SUPPORTING CONCURRENT RADIO ACCESS TECHNOLOGIES

RELATED APPLICATIONS

This application claims the benefit of priority to International Patent Application No. PCT/CN2016/074016, entitled “System and Methods for Improving Performance During Radio Resource Control (RRC) Connected State on a Wireless Communication Device Supporting Concurrent Radio Access Technologies” filed February 18, 2016.

BACKGROUND

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. One example of such a network is the Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN) . The UTRAN is the radio access network (RAN) defined as a part of UMTS, a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP) . 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) .

An ongoing goal of mobile communications is achieving high rates of data transmission and reception, while minimizing the amount of power consumed. As such, wireless communication devices may operate on networks using Long Term Evolution (LTE) standards, which enhance GSM, UMTS and/or CDMA2000 by improving support of mobile broadband Internet access. Such improved support may be based, for example, on increased capacity and speed of wireless data networks, integration with other standards and multiple-input multiple-output (MIMO) antenna technology.

SUMMARY

Systems, methods, and devices of various aspects enable a wireless communication device having a radio frequency (RF) resource supporting at least a first and second radio access technology (RAT) to manage uplink resource grants. In some aspect methods and devices, managing the uplink resource grants may include detecting that a first protocol stack is in a radio resource control (RRC) -connected state in a network associated with the first RAT, detecting a tune-away event on the first protocol stack, and triggering a first scheduling request procedure on the first protocol stack and implementing a protection window mechanism during a time window following the tune-away duration. In a tune-away event, the RF resource tunes from the network associated with the first RAT to a network associated with the second RAT, and the RF resource tunes back to the network associated with the first RAT after a tune-away duration. In some aspects, implementing the protection window mechanism includes starting a short buffer status report (BSR) timer in response to detecting a BSR triggered on the first protocol stack, determining whether an uplink resource grant is received on the first protocol stack before expiration of the short BSR timer, and triggering a second scheduling request procedure on the first protocol stack in response to determining that an uplink resource grant is not received on the first protocol stack before the expiration of the short BSR timer.

In some embodiments, the time window is a longer of 40 physical downlink control channels (PDCCH) subframes and a short discontinuous reception (DRX) cycle configured for the first protocol stack. Some embodiments may further include determining whether an amount of time elapsed since an end of the tune-away duration is greater than the time window, determining whether a new tune-away event has started, and stopping the protection window mechanism in response to determining that a new tune-away event has started or that the amount of time elapsed since the end of the tune-away duration is greater than the time window.

Some embodiments may also include generating the short BSR timer by modifying a retransmission BSR timer configured by the network associated with the first RAT, and stopping the protection window mechanism may include resetting the retransmission BSR timer according to the network associated with the first RAT. Some embodiments may also include triggering the BSR on the first protocol stack by creating a data occupancy report for uplink data that is currently pending for transmission.

In some embodiments, the short BSR timer may be a new BSR timer with an expiration of around 20 ms, and stopping the protection window mechanism may include discarding the new BSR timer. In some embodiments, the first and second scheduling request procedures may include generating an uplink resource request message for transmission to the network associated with the first RAT, and attempting to transmit the uplink resource request message on a physical uplink control channel.

In some embodiments, the tune-away event on the first protocol stack may include tuning the RF resource from a network associated with a first subscriber identity module (SIM) to a network associated with a second SIM, in which the tune-away duration is at least 10 ms.

In some embodiments, the tune-away event on the first protocol stack may include tuning the RF resource from a network associated with a first subscriber identity module (SIM) to a network associated with a second SIM, in which the tune-away duration is around 3–4 ms.

In some embodiments, the tune-away event on the first protocol stack may include performing a burst-level tune-away of the RF resource from the network associated with the first RAT to the network associated with the second RAT, in which the burst-level tune-away maintains on the first protocol stack an uplink resource grant for the network associated with the first RAT.

In some embodiments, the first protocol stack may be associated with a first subscriber identity module (SIM) . In some embodiments, the network associated with the second RAT may be a network supported by a second SIM, in which case operations in the network supported by the second SIM may be implemented by a second protocol stack. In some embodiments, the networks associated with first and second RATs may be independently operated. In some embodiments, operations in the network associated with the second RAT may be implemented by a second protocol stack, and the first and second protocol stacks may both be associated with an operator providing a hybrid system implementing at least the first and second RATs.

Various embodiments include a wireless communication device including a wireless communication device configured with at least the first and second RF receive resources, and a processor configured with processor-executable instructions to perform operations of the methods summarized above. Various embodiments also include a non-transitory processor-readable medium on which is stored processor-executable instructions configured to cause a processor of a wireless communication device to perform operations of the methods summarized above. Various embodiments also include a wireless communication device having means for performing functions of the methods summarized above.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate exemplary embodiments of the invention, and together with the general description given above and the detailed description given below, serve to explain the features herein.

FIG. 1A is a communication system block diagram of a network suitable for use with various embodiments.

FIG. 1B is system block diagram of an Evolved Packet System (EPS) suitable for use with various embodiments.

FIG. 2 is a block diagram illustrating a wireless communication device according to various embodiments.

FIG. 3 is a block diagram illustrating the user plane LTE protocol stack according to various embodiments.

FIGS. 4A and 4B are process flow diagrams illustrating a method for enabling efficient management of uplink resource grants following a tune-away event on an example wireless communication device according to various embodiments.

FIG. 5 is a component diagram of an example wireless communication device suitable for use with various embodiments.

FIG. 6 is a component diagram of another example wireless communication device suitable for use with various embodiments.

DETAILED DESCRIPTION

The various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References made to particular examples and implementations are for illustrative purposes, and are not intended to limit the scope of the invention or the claims.

Wireless communication devices may include a single radio frequency (RF) resource configured with multiple receive paths, allowing the device to receive and support communications on more than one radio access technology. Such wireless communication devices, which may be referred to as concurrent RAT (CRAT) - enabled devices, can use the shared RF resource and multiple receive paths to tune to and from networks implemented by different carriers (e.g., using multiple subscriber identity modules (SIMs) ) , and/or the same carrier (e.g., in a hybrid system) . Therefore, receive chain configurations may provide wireless communication devices with a variety of tune-away options, such as tuning away to a network associated with the same carrier, associated with a different carrier in the same radio access technology, associated with a different carrier in a different radio access technology, etc.

In order to avoid dropping the radio resource control (RRC) connection to a network or suspending a data communication, a tune-away may be performed quickly, such as within a single time division multiple access (TDMA) frame or timeslot of a TDMA frame. In this manner, the wireless communication device may maintain uplink resources that were allocated for data transmission on the wireless communication device prior to the tune-away period. When no uplink data is received by the network within a short period of time, in order to save power during the connection, the network may cause the wireless communication device to transition into a sleep part of a connected discontinuous reception (CDRX) cycle ( “CDRX-off state” ) . In other words, any downlink scheduling grants to be sent to the device are delayed, and the network does not monitor uplink status reports or other data.

Upon tuning back to the first network, a scheduling request may be triggered in the media access control (MAC) layer if there is uplink data for transmission to the network. When previous uplink resources were assigned to the wireless communication device before the tune-away period without the data session being suspended, such resource assignment may be maintained through the tune away period. In such cases, the maintained resource grant prevents the scheduling request from being transmitted. That is, the physical layer will recognize that resources have been allocated to the wireless device, and will use the existing resource grant to send an uplink buffer status report and other uplink data. Based on the CDRX-off state, however, the network will not respond to the data from the wireless communication device. Instead, the wireless communication device may wait until the next active part of the CDRX cycle ( “CDRX-on state” ) in order to transmit a scheduling request to the network, in order to receive a new grant of uplink resources. As such, a period of time in which the network does not grant uplink resources may occur after a tune-away event, and may last one or multiple short CDRX cycles. Therefore, both uplink and downlink throughput may be significantly impacted by the CDRX operations at the network for tune-away events of relatively short durations.

Wireless communication protocols may include mechanisms that enhance a network’s capability to serve a large number of devices simultaneously. For example, the Long Term Evolution (LTE) protocol provides state definitions (i.e., RRC states) for wireless communication devices that specify actions and behaviors between a device and a network. For example, an LTE network may track the RRC state of a wireless communication device by maintaining a corresponding RRC state representation. When the RRC connected state is set in the LTE network and is reflected in the device operations, data exchange may occur over a radio bearer between the wireless communication device and the network.

In order to perform such data exchanges, the LTE network allocates radio resources to the wireless communication device. Both uplink and downlink resource allocations may be adaptively performed by a scheduler, taking into account the current traffic pattern and radio propagation characteristics associated with each wireless communication device. Assigning resources to a wireless communication device may also be affected by status reports and feedback that the wireless communication device transmits in the uplink, as well as expiration timers that may run on the network or wireless communication device.

Systems, methods, and devices of various embodiments enable a wireless communication device capable of communicating using a number of different radio access technologies (RAT) to efficiently receive uplink resource grants from the network when data is pending for transmission following a tune-away to another network. Such control of uplink resource grants may involve setting a protection window, and modifying an existing buffer status report (BSR) timer to enable the wireless communication device to transmit a triggered scheduling request to the network. Further, such control may allow transmission of a scheduling request without unnecessary repetition. In this manner, the wireless communication device may avoid the network dropping the communication, as well as avoid wasting resources and processing time by sending data on past resource grants that are no longer valid on the network.

The terms “wireless device, ” and “wireless communications device” are used interchangeably herein to refer to any one or all of cellular telephones, smart phones, personal or mobile multi-media players, personal data assistants (PDAs) , laptop computers, tablet computers, smart books, palm-top computers, wireless electronic mail receivers, multimedia Internet enabled cellular telephones, wireless gaming controllers, and similar personal electronic devices that include a programmable processor and memory and circuitry for establishing wireless communication pathways and transmitting/receiving data via wireless communication pathways.

As used herein, the terms “SIM, ” “SIM card, ” and “subscriber identity module” are used interchangeably to refer to a memory that may be an integrated circuit or embedded into a removable card, and that stores an International Mobile Subscriber Identity (IMSI) , related key, and/or other information used to identify and/or authenticate a wireless device on a network and enable a communication service with the network. Examples of SIMs include the Universal Subscriber Identity Module (USIM) provided for in the LTE 3GPP standard, and the Removable User Identity Module (R-UIM) provided for in the 3GPP2 standard. Universal Integrated Circuit Card (UICC) is another term for SIM. Because the information stored in a SIM enables the wireless device to establish a communication link for a particular communication service or services with a particular network, the term “SIM” is also be used herein as a shorthand reference to the communication service associated with and enabled by the information stored in a particular SIM as the SIM and the communication network, as well as the services and subscriptions supported by that network, correlate to one another. Similarly, the term SIM may also be used as a shorthand reference to the protocol stack and/or modem stack and communication processes used in establishing and conducting communication services with subscriptions and networks enabled by the information stored in a particular

As used herein, the term “RF resource” refers to the components in a communication device that send, receive, and decode radio frequency signals. An RF resource typically includes a number of components coupled together that transmit RF signals, referred to as a “transmit chain, ” and a number of components coupled together that receive and process RF signals, interchangeably referred to herein as a “receive chain, ” “RF receive chain, ” or “receive path. ”

As used herein, the terms “multi-SIM wireless communication device, ” “multi-SIM wireless device, ” and “dual-SIM wireless communication device” may interchangeably describe a wireless device that is configured with more than one SIM.

Awireless communication device that supports two or more subscriptions associated with SIMs using a shared RF resource is referred to herein as a multi-SIM multi-standby (MSMS) communication device, ” “MSMS wireless device, ” “dual-SIM dual standby (DSDS) communication device, ” and DSDS wireless device” refer to a wireless communication device that is configured with more than one SIM and allows idle-mode operations to be performed on two networks simultaneously, as well as selective communications on one network while performing idle-mode operations on at least one other network. Dual-SIM dual-standby communication devices are an example of a type of MSMS communication device.

As used herein, the terms “network, ” “system, ” “wireless network, ” “cellular network, ” and “wireless communication network” may interchangeably refer to a portion or all of a wireless network of a carrier associated with a wireless device and/or subscription on a wireless device. The techniques described herein may be used for various wireless communication networks such as code division multiple access (CDMA) , TDMA, frequency division multiple access (FDMA) , orthogonal FDMA (OFDMA) , single carrier FDMA (SC-FDMA) and other networks. In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support at least one radio access technology, which may operate on one or more frequency or range of frequencies. Reference may be made to wireless networks that use LTE standards, and therefore the terms “Evolved Universal Terrestrial Radio Access, ” “E-UTRA, ” and “eNode” may also be used interchangeably herein to refer to a wireless network. However, such references are provided merely as examples, and are not intended to exclude wireless networks that use other communication standards.

As used herein, the terms “concurrent RAT (CRAT) , ” “CRAT-enabled, ” and “multi-RAT” may interchangeably describe a wireless communication device that supports at least downlink communications with more than one RAT using a shared RF resource. A CRAT-enabled wireless communication device may be configured with one or more RF resources corresponding to each of the supported RATs, which may be associated with a single SIM (i.e., in a hybrid mode wireless device) or with separate SIMs (i.e., in an MSMS wireless device) . That is, at a given time, a CRAT-enabled wireless device may be able to actively receive communications on any one of the supported RATs.

As used herein, the terms “idle discontinuous reception mode, ” “IDRX mode, ” and “IDRX cycle” may interchangeably refer to an idle state process that involves alternating sleep periods (during which power consumption is minimized) and awake (or “wake-up” ) periods in which normal power consumption and reception are returned, and the wireless device monitors a paging channel.

As used herein, the terms “connected discontinuous reception (CDRX) mode, ” “CDRX mode, ” and “CDRX cycle” may interchangeably refer to a connected state process that involves alternating between an “On duration” (CDRX-on period, or CDRX-on state) in which the downlink control channel is continuously monitored for scheduling messages, and an “Off duration” (CDRX-off period, or CDRX-off state) in which reception of downlink channels may be skipped to save power, with downlink traffic buffered until the next CDRX-on period. The length of a CDRX cycle, measured as the interval between the start of a CDRX-on period and the start of the next CDRX-on period, may be dynamically configured based on the amount of time between data transfers.

Wireless communication networks are widely deployed to provide various communication services such as voice, packet data, broadcast, messaging, and so on. These wireless networks may be capable of supporting communications for multiple users by sharing the available network resources.

The techniques described herein may be used for various wireless communication networks such as CDMA networks, TDMA networks, FDMA networks, OFDMA networks, SC-FDMA networks, etc. Technologies that may be implemented by such wireless communication networks may include Wireless networks may also utilize various radio technologies such as Wideband-CDMA (W-CDMA) , CDMA2000, Global System for Mobile Communications (GSM) , etc. For example, a CDMA network may implement Universal Terrestrial Radio Access (UTRA) (including Wideband-CDMA (W-CDMA) standards) , CDMA2000 (including IS-2000, IS-95 and/or IS-856 standards) , etc. In another example, a TDMA network may implement Global System for Mobile Communications (GSM) . In another example, an OFDMA network may implement Evolved UTRA (E-UTRA) (including LTE standards) , Institute of Electrical and Electronics Engineers (IEEE) 802.11 (WiFi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-

etc. These multiple technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless communication devices to communicate on a municipal, national, regional, and/or global level.

While specific receiver operations may be described herein with reference to a degree of two (i.e., two RATs, two SIMs, two receive chains, etc. ) , such references are used as example and are not meant to preclude embodiments capable of communications on three or more RATs and/or with three or more SIMs. The terms “receiver” and/or “transmitter” may respectively indicate a receive chain and/or transmit chain, and/or portions thereof in use for radio links. Such portions of the receive chain and/or transmit chain may be parts of the RF resource that include, without limitation, an RF front end, components of the RF front end (including a receiver unit and/or transmitter unit) , one or more antenna, etc. Portions of a receive chain and/or transmit chain may be integrated into a single chip, or distributed over multiple chips. Also, the RF resource, or the parts of the RF resource, may be integrated into a chip along with other functions of the wireless communication device.

Various embodiments may be implemented within a variety of communication systems, such as the example communication system 100 illustrated in FIG. 1A. The communication system 100 may include one or more wireless communication devices 102, a wireless communication network 104, and network servers 106 coupled to the wireless communication network 104 and to the Internet 108. In some embodiments, the network server 106 may be implemented as a server within the network infrastructure of the wireless communication network 104.

Atypical wireless communication network 104 may include a plurality of cell base stations 110 coupled to a network operations center 112, which operates to connect voice and data calls between the wireless communication devices 102 (e.g., tablets, laptops, cellular phones, etc. ) and other network destinations, such as via telephone land lines (e.g., a plain ordinary telephone system (POTS) network, not shown) and the Internet 108. The wireless communication network 104 may also include one or more servers 116 coupled to or within the network operations center 112 that provide a connection to the Internet 108 and/or to the network servers 106. Communications between the wireless communication devices 102 and the wireless communication network 104 may be accomplished via two-way wireless communication links 114, such as GSM, UMTS, EDGE, fifth generation (5G) , fourth generation (4G) , 3G, CDMA, TDMA, LTE, and/or other communication technologies.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support one or more radio access technology, which may operate on one or more frequency (also referred to as a carrier, channel, frequency channel, etc. ) in the given geographic area in order to avoid interference between wireless networks of different radio access technologies.

Upon power up, the wireless communication device 102 may search for wireless networks from which the wireless communication device 102 can receive communication service. In various embodiments, the wireless communication device 102 may be configured to prefer LTE networks when available by defining a priority list in which LTE frequencies occupy the highest spots. The wireless communication device 102 may perform registration processes on one of the identified networks (referred to as the serving network) , and the wireless communication device 102 may operate in a connected mode to actively communicate with the serving network. Alternatively, the wireless communication device 102 may operate in an idle mode and camp on the serving network if active communication is not required by the wireless communication device 102. In the idle mode, the wireless communication device 102 may identify all RATs in which the wireless communication device 102 is able to find a “suitable” cell in a normal scenario or an “acceptable” cell in an emergency scenario, as specified in the LTE standards, such as 3GPP Technical Specification (TS) 36.304 version 8.2.0 Release 8, entitled “3rd Generation Partnership Project； Technical Specification Group Radio Access Network；； Evolved Universal Terrestrial Radio Access (E-UTRA) ； User Equipment (UE) procedures in idle mode. ”

The wireless communication device 102 may camp on a cell belonging to the RAT with the highest priority among all identified cells. The wireless communication device 102 may remain camped on that cell until either the control channel no longer satisfies a threshold signal strength or signals from a cell of a higher priority RAT reach the threshold signal strength. Such cell selection/reselection operations for the wireless communication device 102 in the idle mode are also described in 3GPP TS 36.304 version 8.2.0 Release 8.

FIG. 1B illustrates a network architecture 150 that includes an Evolved Packet System (EPS) . With reference to FIGS. 1A–1B, in the network architecture 150 the wireless communication device 102 may be connected to an LTE access network, for example, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) 152. In the various embodiments, the E-UTRAN 152 may be a network of LTE base stations (i.e., eNodeBs) (e.g., 110 in FIG. 1A) , which may be connected to one another via an X2 interface (e.g., backhaul) (not shown) .

In various embodiments, each eNodeB may provide to wireless devices an access point to an LTE core (e.g., an Evolved Packet Core) . For example, the EPS in the network architecture 150 may further include an Evolved Packet Core (EPC) 154 to which the E-UTRAN 152 may connect. In various embodiments, the EPC 154 may include at least one Mobility Management Entity (MME) 162, a Serving Gateway (SGW) 160, and a Packet Data Network (PDN) Gateway (PGW) 163.

In various embodiments, the E-UTRAN 152 may connect to the EPC 154 by connecting to the SGW 160 and to the MME 162 within the EPC 154. The MME 162, which may also be logically connected to SGW 160, may handle tracking and paging of the wireless communication device 102 and security for E-UTRAN access on the EPC 154. The MME 162 may be linked to a Home Subscriber Server (HSS) 156, which may support a database containing user subscription, profile, and authentication information. Further, the MME 162 provides bearer and connection management for user Internet protocol (IP) packets, which are transferred through the SGW 160. The SGW 160 may be connected to the PGW 163, which may provide IP address allocation to the wireless communication device 102, as well as other functions. The PGW 163 may be connected to the Operator's IP Services 158, which may include, for example, the Internet, an Intranet, an IP Multimedia Subsystem (IMS) , a PS Streaming Service (PSS) , etc.

The network architecture 150 may also include circuit-switched (CS) and packet-switched (PS) networks. In some embodiments, the wireless communication device 102 may be connected to the CS and/or PS packet switched networks by connecting to a legacy second generation (2G) /third generation (3G) access network 164. In some embodiments, the 2G/3G access network 164 may be, for example, one or more UTRAN, GSM Enhanced Data rates for Global Evolution (EDGE) Radio Access Network (GERAN) , CDMA2000 1xRTT, CDMA2000 1xEV-DO, etc. In the various embodiments, the 2G/3G access network 164 may include a network of base stations (e.g., base transceiver stations (BTSs) , nodeBs, radio base stations (RBSs) , etc. ) (e.g., 110) , as well as at least one base station controller (BSC) or radio network controller (RNC) . In various embodiments, the 2G/3G access network 164 may connect to the circuit switched network via an interface with (or gateway to) a Mobile switching center (MSC) and associated Visitor location register (VLR) , which may be implemented together as MSC/VLR 166. In the CS network, the MSC/VLR 166 may connect to a CS core 168, which may be connected to external networks (e.g., the public switched telephone network (PSTN) ) through a Gateway MSC (GMSC) 170.

In various embodiments, the 2G/3G access network 164 may connect to the PS network via an interface with (or gateway to) a Serving GPRS support node (SGSN) 172, which may connect to a PS core 174. In the PS network, the PS core 174 may be connected to external PS networks, such as the Internet and the Operator’s IP services 158 through a Gateway GPRS support node (GGSN) 176.

Anumber of techniques may be employed by LTE network operators to enable voice calls to the wireless communication device 102 when camped on an eNodeB of the E-UTRAN 152 (i.e., LTE network) . The LTE network may co-exist in mixed (i.e., hybrid) networks with the CS and PS networks, with the MME 162 serving the wireless communication device 102 for utilizing PS data services over the LTE network, the SGSN 172 serving the wireless communication device 102 for utilizing PS data services in non-LTE areas, and the MSC/VLR 166 serving the wireless communication device 102 for utilizing voice services. In various embodiments, the wireless communication device 102 may be able to use a single RF resource for both voice and LTE data services by implementing circuit-switched fallback (CSFB) to switch between accessing the E-UTRAN 152 and the legacy 2G/3G access network 164.

The mixed network may be enabled to facilitate circuit switched fallback (CSFB) via an interface (SGs) between the MME 162 and the MSC/VLR 166. The interface enables the wireless communication device 102 to utilize a single RF resource to be both CS and PS registered while camped on the LTE network, which enables delivery CS pages via the E-UTRAN 152. A CS page may initiate the CSFB procedure, which may cause the wireless device to transition to the CS network and utilize the CS call setup procedures.

The various embodiments may be implemented in LTE-Advanced wireless networks that have been deployed or that may be deployed in the future. LTE-Advanced communications typically use spectrum in up to 20 MHz bandwidths allocated in a carrier aggregation of up to a total of 100 MHz (5 component carriers) used for transmission in each direction.

In various embodiments, modulation and radio access schemes may be employed by a high speed access network (e.g., an E-UTRAN) , and may vary depending on the particular telecommunications standard being deployed. For example, in LTE applications, orthogonal frequency-division multiplexing (OFDM) may be used on the downlink, while single-carrier frequency-division multiple access (SC-FDMA) may be used on the uplink to support both frequency division duplexing (FDD) and time division duplexing (TDD) .

While the various embodiments may be described herein with respect to LTE, various embodiments but may be extended to other telecommunication standards employing other modulation and multiple access techniques. By way of example, the various embodiments may be extended to Evolution-Data Optimized (EV-DO) and/or Ultra Mobile Broadband (UMB) , each of which are air interface standards promulgated by the 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family to provide broadband Internet access to wireless devices. The various embodiments may also be extended to UTRA employing W-CDMA) , GSM, Ultra Mobile Broadband (UMB) , IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, and/or Flash-OFDM employing OFDMA. The actual wireless communication standard and the access technology employed may depend on the specific application and the overall design constraints imposed on the system.

FIG. 2 is a functional block diagram of an example wireless communication device 200 that is suitable for implementing various embodiments. With reference to FIGS. 1A–2, the wireless communication device 200 may be similar to one or more of the wireless communication devices 102 as described. The wireless communication device 200 may include a SIM interface 202, which may represent one or multiple SIM interfaces. The SIM interface 202 may receive a first SIM 204 that is associated with a first subscription. In some embodiments, the wireless communication device 200 may also include a second SIM interface as part of the SIM interface 202, which may receive a second SIM 204 that is associated with a second subscription. In some embodiments, this configuration may be repeated for further SIM interfaces and/or SIMs (e.g., third, fourth, etc. ) (not shown) .

ASIM in various embodiments may be a Universal Integrated Circuit Card (UICC) that is configured with SIM and/or USIM applications, enabling access to GSM and/or UMTS networks. The UICC may also provide storage for a phone book and other applications. Alternatively, in a CDMA network, a SIM may be a UICC removable user identity module (R-UIM) or a CDMA subscriber identity module (CSIM) on a card.

Each SIM 204 may have a CPU, ROM, RAM, EEPROM and I/O circuits. A SIM 204 used in various embodiments may contain user account information, an IMSI a set of SIM application toolkit (SAT) commands and storage space for phone book contacts. A SIM 204 may further store home identifiers (e.g., a System Identification Number (SID) /Network Identification Number (NID) pair, a Home PLMN (HPLMN) code, etc. ) to indicate the SIM network operator provider. An Integrated Circuit Card Identity (ICCID) SIM serial number may be printed on the SIM card for identification.

The wireless communication device 200 may include at least one controller, such as a general purpose processor 206, which may be coupled to a coder/decoder (CODEC) 208. The CODEC 208 may in turn be coupled to a speaker 210 and a microphone 212. The general purpose processor 206 may also be coupled to at least one memory 214. The memory 214 may be a non-transitory tangible computer readable storage medium that stores processor-executable instructions. For example, the instructions may include routing communication data relating to the first or second subscription though a corresponding baseband-RF resource chain. The memory 214 may store operating system (OS) , as well as user application software and executable instructions.

The general purpose processor 206 and memory 214 may each be coupled to at least one baseband-modem processor 216. Each SIM 204 in the wireless communication device 200 may be associated with a baseband-RF resource chain that includes a baseband-modem processor 216 and at least one receive block (e.g., RX1, RX2) of an RF resource 218. In various embodiments, baseband-RF resource chains may include physically or logically separate baseband modem processors (e.g., BB1, BB2) .

The RF resource 218 may be coupled to at least one antenna 220 and may perform transmit/receive functions for the wireless services associated with the SIM (s) 204 of the wireless communication device 200. In some embodiments, the RF resource 218 may be coupled to multiple wireless antenna (s) 220 for sending and receiving RF signals for multiple versions of an RF signal, SIMs 204, thereby enabling the wireless communication device 200 to use receive diversity and/or multiple-input multiple-output (MIMO) operations. The RF resource 218 may include separate receive and transmit functionalities, or may include a transceiver that combines transmitter and receiver functions. In various embodiments, the transmit functionalities of the RF resource 218 may be implemented by at least one transmit block (TX) , which may represent circuitry associated with one or more radio access technologies/SIMs

In particular embodiments, the general purpose processor 206, memory 214, baseband-modem processor (s) 216, and RF resource 218 may be included in a system-on-chip device 222. The one or more SIM 204 and corresponding interface (s) 202 may be external to the system-on-chip device 222. Further, various input and output devices may be coupled to components of the system-on-chip device 222, such as interfaces or controllers. Example user input components suitable for use in the wireless communication device 200 may include, but are not limited to, a keypad 224 and a touchscreen display 226.

In some embodiments, the keypad 224, touchscreen display 226, microphone 212, or a combination thereof, may perform the function of receiving the request to initiate an outgoing call. For example, the touchscreen display 226 may receive a selection of a contact from a contact list or receive a telephone number. In another example, either or both of the touchscreen display 226 and microphone 212 may perform the function of receiving a request to initiate an outgoing call. For example, the touchscreen display 226 may receive selection of a contact from a contact list or to receive a telephone number. As another example, the request to initiate the outgoing call may be in the form of a voice command received via the microphone 212. Interfaces may be provided between the various software modules and functions in the wireless communication device 200 to enable communication between them, as is known in the art.

The baseband-modem processor of a wireless communication device may be configured to execute software including at least one protocol stack associated with at least one SIM. SIMs and associated protocol stacks may be configured to support a variety of communication services that fulfill different user requirements. Further, a particular SIM may be provisioned with information to execute different signaling procedures for accessing a domain of the core network associated with these services and for handling data thereof.

As described above, a wireless communication device in the various embodiments may support a number of radio access technologies (RATs) to support communication with different wireless networks. For example, the radio technologies may include a wide area network (e.g., third generation partnership project (3GPP) long term evolution (LTE) or 1x radio transmission technology (1xRTT or 1x)) , wireless local area network (WLAN) , Bluetooth and/or the like. Multiple antennas and/or receive blocks may be provided to facilitate multimode communication with various combinations of antenna and receiver/transmitter configurations. Each radio technology may transmit or receive signals via one or more antennas.

In various embodiments, the RF resource 218 may be configured with receiver and transmitter circuitry to support multiple radio access technologies/wireless networks that operate according to different wireless communication protocols. Such circuitry may allow the RF resource 218 to process signals associated with different communication standards, and may include or provide connections to different sets of amplifiers, digital to analog converters, analog to digital converters, filters, voltage controlled

FIG. 3 illustrates an example of a radio protocol stack for the user and control planes in LTE. With reference to FIGS. 1–3, the wireless communication device 200 may implement software architecture 300 to communicate with an eNodeB 350 of an access network (e.g., E-UTRAN 152) associated with one or more SIM. In various embodiments, layers in software architecture 300 may form logical connections with corresponding layers in software of the eNodeB 350. The software architecture 300 may be distributed among one or more processors, such as the baseband modem processor 216. While illustrated with respect to one radio protocol stack, in a multi-SIM wireless device, the software architecture 300 may include multiple protocol stacks, each of which may be associated with a different RAT, and optionally, a different SIM (e.g., two protocol stacks associated with two SIMs 204, respectively, in a DSDS wireless device) . Further, while described below with reference to LTE communication layers, the software architecture 300 may support any of variety of standards and protocols for wireless communications, and/or may include additional protocol stacks that support any of variety of standards and protocols wireless communications.

The software architecture 300 may include a Non Access Stratum (NAS) 302 and an Access Stratum (AS) 304. The NAS 302 may include functions and protocols to support packet filtering, security management, mobility control, session management, and traffic and signaling between a SIM (s) of the wireless communication device (e.g., SIM (s) 204) and its core network. The AS 304 may include functions and protocols that support communication between a SIM (s) (e.g., SIM (s) 204) and entities of supported access networks (e.g., an eNodeB) . In particular, the AS 304 may include at least three layers (Layer 1, Layer 2, and Layer 3) , each of which may contain various sub-layers.

In the user and control planes, Layer 1 (L1) of the AS 304 may be a physical layer 306, which may oversee functions that enable transmission and/or reception over the air interface. Examples of such physical layer 306 functions may include cyclic redundancy check (CRC) attachment, coding blocks, scrambling and descrambling, modulation and demodulation, signal measurements, MIMO, etc.

In the user and control planes, Layer 2 (L2) of the AS 304 may be responsible for the link between the wireless communication device 200 and the eNodeB 350 over the physical layer 306. In the various embodiments, Layer 2 may include a MAC sublayer 308, a radio link control (RLC) sublayer 310, and a packet data convergence protocol (PDCP) 312 sublayer, each of which form logical connections terminating at the eNodeB 350.

In the control plane, Layer 3 (L3) of the AS 304 may include a radio resource control (RRC) sublayer 3. While not shown, the software architecture 300 may include additional Layer 3 sublayers, as well as various upper layers above Layer 3. In various embodiments, the RRC sublayer 313 may provide functions including broadcasting system information, paging, and establishing and releasing an RRC signaling connection between the wireless communication device 200 and the access network (e.g., eNodeB of E-UTRAN 152) .

In various embodiments, the PDCP sublayer 312 may provide uplink functions including multiplexing between different radio bearers and logical channels, sequence number addition, handover data handling, integrity protection, ciphering, and header compression. In the downlink, the PDCP sublayer 312 may provide functions that include in-sequence delivery of data packets, duplicate data packet detection, integrity validation, deciphering, and header decompression.

In the uplink, the RLC sublayer 310 may provide segmentation and concatenation of upper layer data packets, retransmission of lost data packets, and Automatic Repeat Request (ARQ) . In the downlink, while the RLC sublayer 310 functions may include reordering of data packets to compensate for out-of-order reception, reassembly of upper layer data packets, and ARQ. In the uplink, MAC sublayer 308 may provide functions including multiplexing between logical and transport channels, random access procedure, logical channel priority, and hybrid- ARQ (HARQ) operations. In the downlink, the MAC layer functions may include channel mapping within a cell, de-multiplexing, discontinuous reception, and HARQ operations.

While the software architecture 300 may provide functions to transmit data through physical media, the software architecture 300 may further include at least one host layer 314 to provide data transfer services to various applications in the wireless communication device 200. In some embodiments, application-specific functions provided by the at least one host layer 314 may provide an interface between the software architecture and the general purpose processor 206.

In other embodiments, the software architecture 300 may include one or more higher logical layers (e.g., transport, session, presentation, application, etc. ) that provide host layer functions. For example, in some embodiments the software architecture 300 may include a network layer (e.g., an IP layer) in which a logical connection terminates at a PDN gateway (e.g., PGW 163) . In some embodiments, the software architecture 300 may include an application layer in which a logical connection terminates at another device (e.g., end user device, server, etc. ) . In some embodiments, the software architecture 300 may further include in the AS 304 a hardware interface 316 between the physical layer 306 and the communication hardware (e.g., one or more RF transceivers) .

In an LTE system, a wireless communication device may be in one of two states defined by the RRC protocol: RRC idle state, and RRC connected state. In the RRC idle state, the wireless communication device is not attached to a network (i.e., eNodeB) , and performs free cell re-selection. In the RRC connected state, the wireless communication device is connected to an eNodeB, which handles mobility and handovers, and is associated with signaling radio bearers and an identifier of the wireless device. While such a connection with an eNodeB may be referred to herein with respect to the wireless communication device, it will be understood that a connection is established on a modem stack associated with an IMSI (i.e., SIM) in the LTE system. That is, reference to the wireless communication device in various procedures and/or communications with a network may be a general reference to the user equipment associated with a subscription in the network. As such, a SIM transferred to different user equipment may be characterized as the same wireless communication device for purposes of network connections.

Operational states in the wireless communication device and the network within the context of an LTE protocol allow multiple devices to operate within limited radio resources. One way to manage sharing of radio resources (e.g., time slots and radio frequencies) is by controlling their allocation to a wireless communication device. For example, LTE networks may allocate resources based on measured quality of uplink and downlink channels for wireless devices in RRC connected state. During normal operation, a wireless communication device that has relatively good quality may be allocated more resources.

In some systems, the wireless communication device reports information about uplink data to the network in order for the network to be able to allocate the proper amount of radio resource. For example, the wireless communication device may generate a buffer status report (BSR) , which indicates the amount of data stored in a buffer of the wireless communication device. The BSR may be a MAC control element that is included in a MAC protocol data unit (PDU) for transmission to the network on a Physical Uplink Shared Channel (PUSCH) . Therefore, the wireless communication device must be allocated an uplink resource to send the BSR.

If such resource is not allocated, the wireless communication device may trigger a scheduling request. The scheduling request may be sent on a dedicated scheduling request channel if a channel has been assigned to the device on the Physical Uplink Control Channel (PUCCH) . Alternatively, the scheduling request may be sent on a contention based Random Access Channel (RACH) . The LTE network controls the maximum number scheduling requests transmitted from each wireless communication device on the PUCCH using a parameter “dsr-TransMax. ” After transmitting the first scheduling request on PUCCH, if uplink resources are not received, the wireless communication device may re-send the scheduling request on PUCCH based on the periodicity. The re-sending of the scheduling request may be performed on the PUCCH for a number of repeats equal to dsr-TransMax. After transmitting the scheduling request for maximum (dsr-TransMax) number of repeats, the wireless communication device may initiate the RACH procedure and cancel all pending (triggered) scheduling requests.

The network may send an uplink resource grant to the wireless communication device on the Physical Downlink Control Channel (PDCCH) in response to the scheduling request. The uplink scheduling grant may assign a number of resource blocks to the wireless communication device for uplink transmission. The uplink resource grant provides information about the time/frequency resources assigned to the wireless communication device for uplink transmission. Further, in some systems, the network may implement a link adaptation function to select transport format properties (e.g., the transport block size, modulation, coding, and antenna scheme for uplink transmission) , which may be sent on the PDCCH along with an identification of the wireless communication device. The resource granted by the network may be of variable size so that the uplink transmission that follows from the wireless communication device can contain various numbers of bits. Upon receiving the uplink grant from the base station, the wireless communication device generates a BSR and sends the buffered data along with the buffer status report using the uplink grant to the network.

When operating in the RRC connected state, power consumption by the wireless communication device is typically very high relative to the RRC idle state. Specifically, since downlink data may arrive at any time, the wireless communication device in RRC connected state should monitor the PDCCH in every sub-frame to check whether downlink data is available. For example, the wireless communication device may decode the PDCCH using a cell radio network temporary identifier (C- RNTI) assigned by the LTE network to the particular wireless communication device (or modem stack associated with LTE operations) .

The wireless communication device (or modem stack associated with LTE operations) may reduce such consumption by implementing CDRX mode. Specifically, in the CDRX mode the wireless communication device may exploit the short periods of time during which no data is sent or received in a data communication session (e.g., during the packet arrival process when there are no outstanding or new packets to be sent or received) to power down most circuitry. When the CDRX mode is enabled, the wireless communication device may cycle between periods of monitoring the PDCCH for downlink data (i.e., CDRX-on state) and periods in which the RF resource is not used and/or is powered down (i.e., CDRX-off state) . In various embodiments, the eNodeB may configure a set of CDRX parameters for the wireless communication device (or modem stack associated with LTE operations) , which may be selected based on the application type such that power and resource savings are maximized. In some embodiments, when the CDRX mode is enabled, the wireless communication device may experience an extended delay in receiving data since some or all of such data may be buffered by the eNodeB to avoid arriving during the CDRX-off state. Therefore, CDRX parameters may be set to achieve a balance between minimizing packet delay while maximizing power savings.

Typically, CDRX cycles are synchronized at the wireless communication device and network side so that the network can schedule wireless communication device data accordingly. In various embodiments, the CDRX cycles may be configured to include a long discontinuous reception (DRX) cycle, and optionally a short DRX cycle. The wireless communication device checks for scheduling messages (by its C-RNTI on the PDCCH) during the CDRX-on state of either the long DRX cycle or short DRX cycle, depending on which CDRX cycle is currently active. If an uplink resource grant or other control message is received during the CDRX-on state, the wireless communication device typically starts a DRX Inactivity Timer and monitors the PDCCH in every subframe. During this period, the wireless communication device may be regarded as being in a continuous reception mode.

The network may configure a number of RRC parameters for CDRX mode on the wireless communication device. For example, the network may configure the DRX Inactivity Timer, which specifies the number of consecutive PDCCH-subframes for which the wireless communication device should be active after successfully decoding a PDCCH indicating a new uplink or downlink transmission. The network may also configure a “shortDRX-cycle” value, which indicates the length of the short DRX cycle in subframes. The short DRX cycle, if configured, is typically the first type of CDRX cycle that needs to be followed when wireless communication device enters CDRX mode. The network may also configure a DRX Short Cycle Timer, which may be expressed as multiples of the short DRX cycle. The DRX Short Cycle Timer value may vary from 1 to 16 (short DRX cycles) . That is, the DRX Short Cycle Timer may provide the number of short DRX cycles to follow before entering the long DRX cycle.

Whenever a scheduling message is received while the DRX Inactivity Timer is running, the wireless communication device restarts the DRX Inactivity Timer. If the DRX Inactivity Timer expires, the wireless communication device moves into a short DRX cycle and starts the “DRX Short Cycle Timer. ” In some systems, the short DRX cycle may also be initiated by a MAC Control Element.

Transitions between the short DRX cycle, the long DRX cycle and continuous reception may be controlled either by a timer or by explicit commands from the eNodeB. During the sleep time, wireless communication device does not monitor PDCCH channels, which results in energy savings. That is, all of the downlink grants are delayed to the nearest wake up period. Uplink transmission is not affected, as the wireless communication device can send an uplink SR at any point (i.e., waking from CDRX-off state and sending a scheduling request to the network when uplink data is detected) .

LTE networks allocate resources based on the measured quality of the uplink and downlink radio channels. During normal operations, a wireless communication device that has relatively good quality is allocated more resources.

Initially, the wireless communication device may detect uplink data for transmission in a transmission buffer. In response to there being data in the transmission buffer, the wireless communication device generates an uplink scheduling request (SR) ,

In some systems, the wireless communication device may send various reports to the network on the PUSCH for use in determining subsequent data transmission payloads. For example, the wireless communication device may transmit channel quality indicator (CQI) , precoding matrix index (PMI) , and rank indicator (RI) , which are used by the network to determine the next sub-frame's downlink resource assignment. Similarly, LTE networks also consider factors other than the radio channel. For example, each wireless communication device periodically sends a BSR and a power headroom report (PHR) as MAC elements, which are used to assign uplink resource grants.

In some systems, quick burst tune-away (QBTA) gaps may be created in the data session of the modem stack associated with the first SIM. That is, the RF resource may employ burst-level tune-away events from the first network to the second network in order to minimize the impact on the throughput of the data communication on the modem stack associated with the first SIM. Specifically, tuning away from the first network to the second network and tuning back to the first network may occur at the burst level, on a slot-by-slot basis, lasting around 3–4 ms. For example, the wireless communication device may tune away from the first network in one burst, read the downlink data from the second network in a second burst, and tune back to the first network in a third burst.

In some embodiments, the QBTA gap in the data communication may prevent the normal immediate suspension of the data communication on the first network supported by the first SIM. In this manner, the first SIM data communication may be able to use the RF resource during the periods in which the second SIM would normally be tuned to the second network but not decoding data bursts.

As described, a wireless communication device with a single RF resource may provide concurrent RAT (CRAT) support using a variety of configurations and modes. For example, the wireless communication device may be a single-radio LTE (SRLTE) device configured to access LTE for data communications and GSM or 1xRTT for voice calls (i.e., GSM/SRLTE or 1x/SRLTE) . In another example, the wireless communication device may be a DSDS wireless device in which the RF resource is shared between two SIMs associated with different RATs (e.g., LTE and GSM or 1xRTT) . In both DSDS and SRLTE configurations, sharing the RF resource may involve enabling a tune-away from a network in one RAT (e.g., LTE) to a network in another RAT (e.g., a non-LTE RAT) .

If an LTE DSDS or SRLTE device (i.e., a CRAT-enabled device) experiences a lengthy tune-away to the non-LTE RAT, the connection with the LTE network may be maintained during the tune-away, but may cause a loss of throughput after tuning back to the LTE network. As established by field tests, such throughput loss may be due in part to a gap in uplink resource grants to the wireless communication device following the tune-away gap. Specifically, the tune-away event may satisfy a condition of a CDRX state switching algorithm. The tune-away event may cause the network to detect a lack of uplink response for more than 3 ms. Consequently, the network may update the corresponding CDRX state represented in the network for the wireless communication device to be CDRX-off. Following such a change, the network typically will not respond to any data transmitted on the PUSCH, but only to control messages and/or scheduling requests on the PUCCH.

The network may maintain a CDRX-off state following the tune-away event until a scheduling request is received or the short DRX cycle ends. In some current systems, upon ending the tune-away event, the wireless communication device may immediately trigger a scheduling request in the MAC layer. Also, depending on the length of the tune-away event, the wireless communication device may have an uplink resource due to a previous grant received, for example, during the tune-away event.

If no previously granted uplink resource is configured in the physical layer, the scheduling request may be transmitted on the PUCCH. As a result, the corresponding CDRX state represented in the network may be switched to the CDRX-on state. However, if a previously granted uplink resource is configured on the physical layer, the scheduling request may be sent on the PUSCH using the previously-granted uplink resource. Since the CDRX-off state is represented in the network, the network does not respond to the uplink PUSCH.

That is, triggering of a CDRX-off state by the network during a tune-away event on the wireless communication device may conflict with the physical layer configurations that persist in the wireless communication device after the end of the tune-away event. In some cases, the wireless communication device may be unable to transmit scheduling requests to the network for a period following the tune-away event. As a result, the network may maintain the CDRX-off state until the end of the CDRX cycle, preventing scheduling of any uplink resource grants for the period of time following the tune-away event.

The various embodiments provide improvements to existing techniques for enabling uplink resource grants from an LTE network (i.e., eNodeB) following a tune-away event on a CRAT-enabled wireless communication device (or modem stack associated with LTE operations) . In particular, the various embodiments avoid negative impacts to data throughput that may result from existing network handling of CDRX states during a tune-away event. That is, the various embodiments may enable triggering the CDRX-on state represented on the network, regardless of whether a previously granted uplink resource is configured for the wireless communication device.

Specifically, the various embodiments set a protection window that starts at the end of the tune-away event. Within the protection window, a short BSR timer may be set. In some embodiments, setting the short BSR timer may involve modifying the existing retransmission BSR timer. In some embodiments, setting the short BSR timer may involve creating a new timer that runs within the protection window. The short BSR timer may be set, for example, to a value of 20 ms.

In various embodiments, the short BSR timer may be started when a BSR is transmitted, and stopped if an uplink resource grant is received. If the short BSR timer expires within the protection window without an uplink resource grant received by the wireless communication device, another scheduling request may be triggered. Specifically, a scheduling request may be sent to the network on the PUCCH following expiration of the BSR timer. Upon transmission of the scheduling request within the protection window, the wireless communication device may exit the protection window. Upon exit, if the short BSR timer was a modified retransmission BSR timer, the wireless communication device may revert the modified retransmission BSR timer back to the network configured value. If the short BSR timer was a new timer, the wireless communication device may discard or reset the short BSR timer.

In some embodiments, the modem stack associated with LTE operations on a wireless communication device may support dual connectivity, enabling simultaneous connection with two eNodeBs. Specifically, each of the two eNodeBs may provide a set of carriers (e.g., a master cell group (MCG) and secondary cell group (SCG)) , as specified in LTE standards such as 3GPP TS 36.321 version 12.8.0 Release 12, entitled “3rd Generation Partnership Project； Technical Specification Group Radio Access Network； Evolved Universal Terrestrial Radio Access (E-UTRA) ； Medium Access Control (MAC) protocol specification. ” The modem stack associated with LTE operations may support simultaneous connections with one or more carriers from each of the MCG and SCG by maintaining separately-configured MAC entities corresponding to the MCG and SCG. Therefore, various embodiments that support dual connectivity may be performed on one or both of the MCG MAC entity and the SCG MAC entity, depending on whether the tune-away event affects a carrier of the MCG and/or SCG.

FIGS. 4A and 4B illustrate a method 400 for enabling efficient uplink resource grants following a tune-away event on a CRAT-enabled wireless communication device when uplink data is pending. Specifically, such management may improve performance by preventing a gap in uplink resource grant on a wireless communication device having uplink data for transmission following a tune-away event.

With reference to FIGS. 1–4B, the operations of the method 400 may be implemented by one or more processors of a wireless device, such as wireless communication device 200. The one or more processors may include, for example, such the general purpose processor 206 and/or baseband modem processor (s) 216, or a separate controller (not shown) that may be coupled to the memory 214 and to the baseband modem processor (s) 216.

In block 402, the wireless device processor may detect that the wireless device is operating in the RRC connected state in a network associated with a first RAT (e.g., an LTE network) while supporting communications with at least one other RAT. As described, the wireless communication device (e.g., 102, 200) may have a single RF resource that supports communications on concurrent RATs (e.g., CRAT-enabled wireless device) . In some embodiments, the wireless device may be a multi-SIM multi-standby (MSMS) device with at least one SIM supporting LTE, while in other embodiments, the wireless device may be an SRLTE wireless device that is configured to connect to at least one hybrid system supporting both LTE and at least one other RAT.

In block 404, the wireless device processor may detect a tune-away event on the RF resource. That is, the wireless device processor may detect that the RF resource has performed a tune-away to a network associated with the second (i.e., non-LTE) RAT. In an MSMS device, the shared RF resource may tune to a network supported by a second SIM, and tune back to the LTE network. In a single SIM device (e.g., an SRLTE device) , the shared RF resource may tune to frequencies of a different RAT within the same service provider system, followed by tuning back to LTE frequencies.

In block 406, the wireless device processor may trigger a scheduling request procedure on a protocol stack associated with the first RAT (e.g., an LTE protocol stack) at the end of the tune-away event. As described, the scheduling request may be transmitted to the LTE network in order to request PUSCH resources for uplink data. Also, at the end of the tune-away event, the wireless device processor may start a protection window for the protocol stack (e.g., LTE protocol stack) in block 408. In various embodiments, the protection window may have a duration set to “Nx, ” which equals the longer of 40 PDCCH subframes and the length of the short DRX cycle configured for the LTE protocol stack. In various embodiments, the protection window may be associated with a short BSR timer. The short BSR timer may be a modification of an existing retransmission BSR timer, or may be a new timer that is independently configured for the protection window. The duration of the short BSR timer may be set, for example, to 20 ms.

In block 410, the wireless device processor may detect that a BSR was triggered on the protocol stack, and may start the short BSR timer.

In determination block 412, the wireless device processor may determine whether the protection window for the protocol stack has ended. In various embodiments, one or more of a number of conditions may be sufficient to end the protection window. For example, determining whether the protection window has ended may involve determining whether a new tune-away event has started, and/or whether a duration of Nx has passed since the tune-away event ended, either of which is sufficient to end the protection window.

In response to determining that the protection window has ended (i.e., determination block 412 ＝ “Yes) , the wireless device processor may remove or reset the short BSR timer and resume normal operations on the protocol stack in block 414. As described, if the short BSR timer is a modification of the retransmission BSR timer, the wireless device processor may restore the retransmission BSR timer to the network configured value. If the short BSR timer is a new timer, the wireless device processor may discard the new timer.

In response to determining that the protection window has not ended (i.e., determination block 412 ＝ “No” ) , the wireless device processor may continue running the short BSR timer until expiration in block 416. In block 418, the wireless device processor may detect that uplink data was pending for transmission at expiration of the short BSR timer. In determination block 420, the wireless device processor may determine whether an uplink resource grant has been received on the protocol stack.

In response to determining that an uplink resource grant has not been received on the protocol stack (i.e., determination block 420 ＝ “No” ) , the wireless device processor may trigger another scheduling request procedure on the protocol stack in block 422. The wireless device processor may exit the protection window by removing or reset the short BSR timer and resuming normal operations on the protocol stack in block 414.

In response to determining that an uplink resource grant has been received on the LTE protocol stack (i.e., determination block 420 ＝ “Yes” ) , the wireless device processor may return to detect a BSR that was triggered and start the short BSR timer on the protocol stack in block 410.

The various embodiments describe improving power efficiency with respect to at least one SIM and RF resource configured to support multiple RATs (e.g., LTE and one or more of GSM, CDMA2000, etc. ) . However, the references to the first and second RATs and corresponding protocol stacks in the descriptions of the various embodiments are arbitrary and used merely for the purposes of providing illustrative examples. The wireless device processor may assign any indicator, name, or other designation to differentiate receive chains associated with one or more RAT and/or protocol stack. Further, the embodiment methods apply the same regardless of which receive chain is being used to tune away from the network of the data communication. Further, while the network of the data communication is referenced as an LTE network or eNodeB, these references are also illustrative examples and the various embodiments may be implemented for receiving data in any of a variety of high-speed networks (e.g., HSPA+, DC-HSPA, EV-DO, etc. ) .

Various embodiments (including, but not limited to, the embodiments discussed above with reference to FIGS. 4A and 4B) may be implemented in any of a variety of wireless devices, an example 500 of which is illustrated in FIG. 5. The wireless device 500 (which may correspond, for example, to the wireless devices 102 and/or 200 in FIGS. 1A–2) may include a processor 502 coupled to a touchscreen controller 504 and an internal memory 506. The processor 502 may be one or more multicore ICs designated for general or specific processing tasks. The internal memory 506 may be volatile or non-volatile memory, and may also be secure and/or encrypted memory, or unsecure and/or unencrypted memory, or any combination thereof.

The touchscreen controller 504 and the processor 502 may also be coupled to a touchscreen panel 512, such as a resistive-sensing touchscreen, capacitive-sensing touchscreen, infrared sensing touchscreen, etc. The wireless device 500 may have one or more radio signal transceivers 508 (e.g.,

Wi-Fi, RF radio) and antennas 510, for sending and receiving, coupled to each other and/or to the processor 502. The transceivers 508 and antennas 510 may be used with the above-mentioned circuitry to implement the various wireless transmission protocol stacks and interfaces. The wireless device 500 may include a cellular network wireless modem chip 516 that enables communication via a cellular network and is coupled to the processor. The wireless device 500 may include a peripheral device connection interface 518 coupled to the processor 502. The peripheral device connection interface 518 may be singularly configured to accept one type of connection, or multiply configured to accept various types of physical and communication connections, common or proprietary, such as USB, Fire Wire, Thunderbolt, or PCIe. The peripheral device connection interface 518 may also be coupled to a similarly configured peripheral device connection port (not shown) . The wireless device 500 may also include speakers 514 for providing audio outputs. The wireless device 500 may also include a housing 520, constructed of a plastic, metal, or a combination of materials, for containing all or some of the components discussed herein. The wireless device 500 may include a power source 522 coupled to the processor 502, such as a disposable or rechargeable battery. The rechargeable battery may also be coupled to the peripheral device connection port to receive a charging current from a source external to the wireless device 500.

Various embodiments (including, but not limited to, the embodiments discussed above with reference to FIGS. 4A and 4B) , may also be implemented within a variety of personal computing devices, an example 600 of which is illustrated in FIG. 6. With reference to FIGS. 1–6, the laptop computer 600 (which may correspond, for example, to the

wireless devices

102, 200 in FIGS. 1A–2) may include a touchpad touch surface 617 that serves as the computer’s pointing device, and thus may receive drag, scroll, and flick gestures similar to those implemented on wireless computing devices equipped with a touchscreen display and described above. A laptop computer 600 will typically include a processor 611 coupled to volatile memory 612 and a large capacity nonvolatile memory, such as a disk drive 613 of Flash memory. The computer 600 may also include a floppy disc drive 614 and a compact disc (CD) drive 615 coupled to the processor 611. The computer 600 may also include a number of connector ports coupled to the processor 611 for establishing data connections or receiving external memory devices, such as a Universal Serial Bus (USB) or Fire

connector sockets, or other network connection circuits for coupling the processor 611 to a network. In a notebook configuration, the computer housing includes the touchpad 617, the keyboard 618, and the display 619 all coupled to the processor 611. Other configurations of the computing device may include a computer mouse or trackball coupled to the processor (e.g., via a USB input) as are well known, which may also be used in conjunction with various embodiments.

With reference to FIGS. 1–6, the

processors

502, 611 may be any programmable microprocessor, microcomputer or multiple processor chip or chips that can be configured by software instructions (applications) to perform a variety of functions, including the functions of various embodiments described above. In some devices, multiple processors may be provided, such as one processor dedicated to wireless communication functions and one processor dedicated to running other applications. Typically, software applications may be stored in the

internal memory

506, 612, 613 before they are accessed and loaded into the

processors

502, 611. The

processors

502, 611 may include internal memory sufficient to store the application software instructions. In many devices the internal memory may be a volatile or nonvolatile memory, such as flash memory, or a mixture of both. For the purposes of this description, a general reference to memory refers to memory accessible by the

processors

502, 611, including internal memory or removable memory plugged into the device and memory within the

processor

502 and 611, themselves.

The foregoing method descriptions and the process flow diagrams are provided merely as illustrative examples and are not intended to require or imply that the steps of various embodiments must be performed in the order presented. As will be appreciated by one of skill in the art the order of steps in the foregoing embodiments may be performed in any order. Words such as “thereafter, ” “then, ” “next, ” etc. are not intended to limit the order of the steps； these words are simply used to guide the reader through the description of the methods. Further, any reference to claim elements in the singular, for example, using the articles “a, ” “an” or “the” is not to be construed as limiting the element to the singular.

While the terms “first” and “second” are used herein to describe data transmission associated with a SIM and data receiving associated with a different SIM, such identifiers are merely for convenience and are not meant to limit the various embodiments to a particular order, sequence, type of network or carrier.

The various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The hardware used to implement the various illustrative logics, logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but, in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. Alternatively, some steps or methods may be performed by circuitry that is specific to a given function.

In one or more exemplary aspects, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a non-transitory computer-readable medium or non-transitory processor-readable medium. The steps of a method or algorithm disclosed herein may be embodied in a processor-executable software module, which may reside on a non-transitory computer-readable or processor-readable storage medium. Non-transitory computer-readable or processor-readable storage media may be any storage media that may be accessed by a computer or a processor. By way of example but not limitation, such non-transitory computer-readable or processor-readable media may include RAM, ROM, EEPROM, FLASH memory, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to store desired program code in the form of instructions or data structures and that may be accessed by a computer. Disk and disc, as used herein, includes compact disc (CD) , laser disc, optical disc, digital versatile disc (DVD) , floppy disk, and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of non-transitory computer-readable and processor-readable media. Additionally, the operations of a method or algorithm may reside as one or any combination or set of codes and/or instructions on a non-transitory processor-readable medium and/or computer-readable medium, which may be incorporated into a computer program product.

The preceding description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the following claims and the principles and novel features disclosed herein.

Claims

A method of managing uplink resource grants on a wireless communication device configured with a radio frequency (RF) resource supporting at least a first radio access technology (RAT) and a second RAT, the method comprising:

detecting that a first protocol stack is in a radio resource control (RRC) -connected state in a network associated with the first RAT；

detecting a tune-away event on the first protocol stack, wherein the RF resource tunes from the network associated with the first RAT to a network associated with the second RAT, wherein the RF resource tunes back to the network associated with the first RAT after a tune-away duration； and

triggering a first scheduling request procedure on the first protocol stack and implementing a protection window mechanism during a time window following the tune-away duration, wherein implementing the protection window mechanism comprises:

starting a short buffer status report (BSR) timer in response to detecting a BSR triggered on the first protocol stack；

determining whether an uplink resource grant is received on the first protocol stack before expiration of the short BSR timer； and

triggering a second scheduling request procedure on the first protocol stack in response to determining that an uplink resource grant is not received on the first protocol stack before expiration of the short BSR timer.
The method of claim 1, wherein the time window comprises a longer of 40 physical downlink control channels (PDCCH) subframes and a short discontinuous reception (DRX) cycle configured for the first protocol stack.
The method of claim 2, further comprising:

determining whether an amount of time elapsed since an end of the tune-away duration is greater than the time window；

determining whether a new tune-away event has started； and

stopping the protection window mechanism in response to determining that a new tune-away event has started or that the amount of time elapsed since the end of the tune-away duration is greater than the time window.
The method of claim 3, further comprising:

generating the short BSR timer by modifying a retransmission BSR timer configured by the network associated with the first RAT； and

triggering the BSR on the first protocol stack by creating a data occupancy report for uplink data that is currently pending for transmission.
The method of claim 4, wherein:

stopping the protection window mechanism comprises resetting the retransmission BSR timer according to the network associated with the first RAT.
The method of claim 3, wherein:

the short BSR timer comprises a new BSR timer with an expiration of around 20 ms； and

stopping the protection window mechanism comprises discarding the new BSR timer.
The method of claim 1, wherein the first and second scheduling request procedures comprise:

generating an uplink resource request message for transmission to the network associated with the first RAT； and

attempting to transmit the uplink resource request message on a physical uplink control channel.
The method of claim 1, wherein the tune-away event on the first protocol stack comprises:

tuning the RF resource from a network associated with a first subscriber identity module (SIM) to a network associated with a second SIM, wherein the tune-away duration comprises at least 10 ms.
The method of claim 1, wherein the tune-away event on the first protocol stack comprises:

tuning the RF resource from a network associated with a first subscriber identity module (SIM) to a network associated with a second SIM, wherein the tune-away duration comprises around 3–4 ms.
The method of claim 1, wherein the tune-away event on the first protocol stack comprises:

performing a burst-level tune-away of the RF resource from the network associated with the first RAT to the network associated with the second RAT, wherein the burst-level tune-away maintains on the first protocol stack an uplink resource grant for the network associated with the first RAT.
The method of claim 1, wherein:

the first protocol stack is associated with a first subscriber identity module (SIM) ；

the network associated with the second RAT comprises a network supported by a second SIM, wherein operations in the network supported by the second SIM are implemented by a second protocol stack； and

the networks associated with first and second RATs are independently operated.
The method of claim 1, wherein:

operations in the network associated with the second RAT are implemented by a second protocol stack； and

the first and second protocol stacks are both associated with an operator providing a hybrid system implementing at least the first and second RATs.
A wireless communication device, comprising:

a radio frequency (RF) resource configured to support at least a first radio access technology (RAT) and a second RAT； and

a processor coupled to the RF resource and configured with processor-executable instructions to:

detect that a first protocol stack is in a radio resource control (RRC) connected state in a network associated with the first RAT；

detect a tune-away event on the first protocol stack, wherein the RF resource tunes from the network associated with the first RAT to a network associated with the second RAT, wherein the RF resource tunes back to the network associated with the first RAT after a tune-away duration； and

trigger a first scheduling request procedure on the first protocol stack and implement a protection window mechanism during a time window following the tune-away duration by:

starting a short buffer status report (BSR) timer in response to detecting a BSR triggered on the first protocol stack；

determining whether an uplink resource grant is received on the first protocol stack before expiration of the short BSR timer； and

triggering a second scheduling request procedure on the first protocol stack in response to determining that an uplink resource grant is not received on the first protocol stack before expiration of the short BSR timer.
The wireless communication device of claim 13, wherein the time window comprises a longer of 40 physical downlink control channels (PDCCH) subframes and a short discontinuous reception (DRX) cycle configured for the first protocol stack.
The wireless communication device of claim 14, wherein the processor is further configured with processor-executable instructions to:

determine whether an amount of time elapsed since an end of the tune-away duration is greater than the time window；

determine whether a new tune-away event has started； and

stop the protection window mechanism in response to determining that a new tune-away event has started or that the amount of time elapsed since the end of the tune-away duration is greater than the time window.
The wireless communication device of claim 15, wherein the processor is further configured with processor-executable instructions to:

generate the short BSR timer by modifying a retransmission BSR timer configured by the network associated with the first RAT； and

trigger the BSR on the first protocol stack by creating a data occupancy report for uplink data that is currently pending for transmission.
The wireless communication device of claim 16, wherein the processor is further configured with processor-executable instructions to stop the protection window mechanism by resetting the retransmission BSR timer according to the network associated with the first RAT.
The wireless communication device of claim 15, wherein the short BSR timer comprises a new BSR timer with an expiration of around 20 ms, and wherein the processor is further configured with processor-executable instructions to stop the protection window mechanism by discarding the new BSR timer.
The wireless communication device of claim 13, wherein the processor is further configured with processor-executable instructions to trigger the first and second scheduling request procedures by triggering procedures to:

generate an uplink resource request message for transmission to the network associated with the first RAT； and

attempt to transmit the uplink resource request message on a physical uplink control channel.
The wireless communication device of claim 13, wherein the processor is further configured with instructions to detect a tune-away event on the first protocol stack by detecting tuning of the RF resource from a network associated with a first subscriber identity module (SIM) to a network associated with a second SIM, wherein the tune-away duration comprises at least 10 ms.
The wireless communication device of claim 13, wherein the processor is further configured with instructions to detect a tune-away event on the first protocol stack by detecting tuning of the RF resource from a network associated with a first subscriber identity module (SIM) to a network associated with a second SIM, wherein the tune-away duration comprises around 3–4 ms.
The wireless communication device of claim 13, wherein the processor is further configured with instructions to detect a tune-away event on the first protocol stack by detecting performance of a burst-level tune-away of the RF resource from the network associated with the first RAT to the network associated with the second RAT, wherein the burst-level tune-away maintains on the first protocol stack an uplink resource grant for the network associated with the first RAT.
The wireless communication device of claim 13, wherein:

the first protocol stack is associated with a first subscriber identity module (SIM) ；

the network associated with the second RAT comprises a network supported by a second SIM, wherein operations in the network supported by the second SIM are implemented by a second protocol stack； and

the networks associated with first and second RATs are independently operated.
The wireless communication device of claim 13, wherein:

operations in the network associated with the second RAT are implemented by a second protocol stack； and

the first and second protocol stacks are both associated with an operator providing a hybrid system implementing at least the first and second RATs.
A wireless communication device, comprising:

a radio frequency (RF) resource configured to support at least a first radio access technology (RAT) and a second RAT；

means for detecting that a first protocol stack is in a radio resource control (RRC) -connected state in a network associated with the first RAT；

means for detecting a tune-away event on the first protocol stack, wherein the RF resource tunes from the network associated with the first RAT to a network associated with the second RAT, wherein the RF resource tunes back to the network associated with the first RAT after a tune-away duration； and

means for triggering a first scheduling request procedure on the first protocol stack and implementing a protection window mechanism during a time window following the tune-away duration, wherein means for implementing the protection window mechanism comprises:

means for starting a short buffer status report (BSR) timer in response to detecting a BSR triggered on the first protocol stack；

means for determining whether an uplink resource grant is received on the first protocol stack before expiration of the short BSR timer； and

means for triggering a second scheduling request procedure on the first protocol stack in response to determining that an uplink resource grant is not received on the first protocol stack before expiration of the short BSR timer.
A non-transitory processor-readable storage medium having stored thereon processor-executable instructions configured to cause a processor of a wireless communication device having a radio frequency (RF) resource configured to support at least a first radio access technology (RAT) and a second RAT to perform operations comprising:

detecting that a first protocol stack is in a radio resource control (RRC) -connected state in a network associated with the first RAT；

detecting a tune-away event on the first protocol stack, wherein the RF resource tunes from the network associated with the first RAT to a network associated with the second RAT, wherein the RF resource tunes back to the network associated with the first RAT after a tune-away duration； and

triggering a first scheduling request procedure on the first protocol stack and implementing a protection window mechanism during a time window following the tune-away duration, wherein implementing the protection window mechanism comprises:

starting a short buffer status report (BSR) timer in response to detecting a BSR triggered on the first protocol stack；

determining whether an uplink resource grant is received on the first protocol stack before expiration of the short BSR timer； and

triggering a second scheduling request procedure on the first protocol stack in response to determining that an uplink resource grant is not received on the first protocol stack before expiration of the short BSR timer.
The non-transitory processor-readable storage medium of claim 26, wherein the stored processor-executable instructions are configured to cause the processor of the wireless communication device to perform operations such that:

the time window comprises a longer of 40 physical downlink control channels (PDCCH) subframes and a short discontinuous reception (DRX) cycle configured for the first protocol stack.
The non-transitory processor-readable storage medium of claim 26, wherein the stored processor-executable instructions are configured to cause the processor of the wireless communication device to perform operations further comprising:

determining whether an amount of time elapsed since an end of the tune-away duration is greater than the time window；

determining whether a new tune-away event has started； and

stopping the protection window mechanism in response to determining that a new tune-away event has started or that the amount of time elapsed since the end of the tune-away duration is greater than the time window.
The non-transitory processor-readable storage medium of claim 28, wherein the stored processor-executable instructions are configured to cause the processor of the wireless communication device to perform operations further comprising:

generating the short BSR timer by modifying a retransmission BSR timer configured by the network associated with the first RAT； and

triggering the BSR on the first protocol stack by creating a data occupancy report for uplink data that is currently pending for transmission.
The non-transitory processor-readable storage medium of claim 29, wherein the stored processor-executable instructions are configured to cause the processor of the wireless communication device to perform operations such that:

stopping the protection window mechanism comprises resetting the retransmission BSR timer according to the network associated with the first RAT；

the short BSR timer comprises a new BSR timer with an expiration of around 20 ms； and

stopping the protection window mechanism comprises discarding the new BSR timer.