Enhanced tune-away mechanism during signaling procedure in multiple subscription communications

In various aspects of the disclosure, an improved tune-away technique is utilized by a user equipment (UE) for wireless communication during a signaling procedure for a primary subscription with reduced impact on paging performance of one or more secondary subscriptions. The UE performs a signaling procedure including receiving at least one protocol data unit (PDU) of a signaling radio bearer (SRB) message from a first network associated with the first subscription. The UE further determines a message type of the SRB message based on the at least one received PDU. If the message type indicates that the SRB message includes a signaling non-critical message, the UE further performs a tune-away procedure to communicate with a second network associated with the second subscription, while the signaling procedure is ongoing.

TECHNICAL FIELD

The technology discussed below relates generally to wireless communication systems, and more particularly, to a mobile station equipped to operate with multiple subscriptions and tune-away methods between the subscriptions.

BACKGROUND

Generally in UMTS networks, mobile communication devices are configured to use a Universal Integrated Circuit Card (UICC) (also commonly referred to as a SIM card) to store the subscriber's identity and information for security and authentication purposes. Some mobile communication devices have multi-SIM capability utilizing multiple UICCs. In multi-SIM applications, mobile communication devices can engage in calls or other services on two or more different subscriptions. These subscriptions might be on the same network or different networks.

As the demand for mobile broadband access continues to increase, research and development continue to advance mobile technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.

BRIEF SUMMARY OF SOME EXAMPLES

In various aspects of the disclosure, an improved tune-away technique is utilized by a user equipment for wireless communication during a signaling procedure for a primary subscription with reduced impact on paging performance of one or more secondary subscriptions.

In one aspect, the disclosure provides a method of wireless communication operable at a user equipment (UE). The UE includes a first subscriber identity module (SIM) associated with a first subscription and a second SIM associated with a second subscription. The UE performs a signaling procedure including receiving at least one protocol data unit (PDU) of a signaling radio bearer (SRB) message from a first network associated with the first subscription. The UE further determines a message type of the SRB message based on the at least one received PDU. If the message type indicates that the SRB message includes a signaling non-critical message, the UE further performs a tune-away procedure to communicate with a second network associated with the second subscription, while the signaling procedure is ongoing.

In one aspect, the disclosure provides a multi-SIM user equipment (UE) including a first subscriber identity module (SIM) associated with a first subscription and a second SIM associated with a second subscription. The multi-SIM UE includes means for performing a signaling procedure including receiving at least one protocol data unit (PDU) of a signaling radio bearer (SRB) message from a first network associated with the first subscription. The multi-SIM UE further includes means for determining a message type of the SRB message based on the at least one received PDU. The multi-SIM UE further includes means for if the message type indicates that the SRB message includes a signaling non-critical message, performing a tune-away procedure to communicate with a second network associated the second subscription, while the signaling procedure is ongoing.

In one aspect, the disclosure provides an apparatus for wireless communication. The apparatus includes a first subscriber module (SIM) associated with a first subscription, a second SIM associated with a second subscription, a first subscription component, a message processing component, and a tune-away control component. The first subscription component is configured to perform a signaling procedure including receiving at least one protocol data unit (PDU) of a signaling radio bearer (SRB) message from a first network associated with the first subscription. The message processing component is configured to determine a message type of the SRB message based on the at least one received PDU. The tune-away control component is configured to if the message type indicates that the SRB message includes a signaling non-critical message, perform a tune-away procedure to communicate with a second network associated with the second subscription, while the signaling procedure is ongoing.

In one aspect, the disclosure provides a computer-readable storage medium including code for causing a user equipment (UE) to perform a signaling procedure. The UE includes a first subscriber module (SIM) associated with a first subscription and a second SIM associated with a second subscription. The codes causes the UE to perform a signaling procedure including receiving at least one protocol data unit (PDU) of a signaling radio bearer (SRB) message from a first network associated with the first subscription. The code further causes the UE to determine a message type of the SRB message based on the at least one received PDU. The code further causes the UE to if the message type indicates that the SRB message includes a signaling non-critical message, perform a tune-away procedure to communicate with a second network associated with the second subscription, while the signaling procedure is ongoing.

DETAILED DESCRIPTION

Some multi-SIM mobile communication devices utilize a shared transceiver or RF chain for multiple subscriptions. However, there are certain limitations on carrying communications simultaneously for multiple subscriptions using a shared transceiver or RF resource. One or more aspects of the disclosure provide a wireless user equipment (UE) configured to enable communication using two or more subscriptions simultaneously. Each subscription may be using the same or different radio access technologies (RAT). In some examples, the RAT may be W-CDMA, GSM, Long-Term Evolution (LTE), Wi-Fi, etc. The UE may have multiple universal subscriber identity module (USIM) applications stored on one or more UICCs (also referred to as smart cards, SIM cards, or SIMs). In some aspects of the disclosure, however, the USIM applications may be stored at the UE without using a UICC or SIM card (e.g., soft or virtual SIM models). A UE with multiple USIM applications may be referred to as a multi-SIM device or having multi-SIM functionality.

In some aspects of the disclosure, an improved tune-away technique is used with a multi-SIM UE during a signaling procedure for a primary subscription without impacting paging performance of one or more secondary subscriptions. In one aspect of the disclosure, the multi-SIM UE may skip a tune-away operation depending on whether or not a signaling radio bearer (SRB) signaling communication ongoing with the primary subscription involves signaling critical messages. In general, signaling critical messages refer to SRB messages that are vital for maintaining the signaling connection between a UE and a network. In one example, signaling critical messages may be SRB messages that need to meet the performance requirements for the SRB procedures in terms of (N1, N2) parameters specified in the 3GPP Technical Specification (TS) 25.331, RRC Protocol Specification, section 13.5, version 12.1.0, which is incorporated herein by reference.

By way of example and not limitation, signaling critical messages include a radio bearer reconfiguration message, a transport channel reconfiguration message, a physical channel reconfiguration message, an active set update message, or any SRB messages that are time critical. However, the present disclosure is not limited to these signaling critical messages, and other suitable signaling critical messages may be used. Signaling non-critical messages may include any SRB messages that are not signaling critical messages as described throughout this specification. In some examples, signaling non-critical messages may be measurement control messages or measurement report messages.

The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards. Referring now toFIG. 1, as an illustrative example without limitation, various aspects of the present disclosure are illustrated with reference to a UMTS network100. A UMTS network includes three interacting domains: a core network104, a radio access network (RAN) (e.g., the UMTS Terrestrial Radio Access Network (UTRAN)102), and a user equipment (UE)110. Among several options available for a UTRAN102, in this example, the illustrated UTRAN102may employ a W-CDMA air interface for enabling various wireless services including telephony, video, data, messaging, broadcasts, and/or other services. A subscription may include one or more services that the UE110may receive from the network. The UTRAN102may include a plurality of Radio Network Subsystems (RNSs) such as an RNS107, each controlled by a respective Radio Network Controller (RNC) such as an RNC106. Here, the UTRAN102may include any number of RNCs106and RNSs107in addition to the illustrated RNCs106and RNSs107. The RNC106is an apparatus responsible for, among other things, assigning, reconfiguring, and releasing radio resources within the RNS107. The RNC106may be interconnected to other RNCs (not shown) in the UTRAN102through various types of interfaces such as a direct physical connection, a virtual network, or the like using any suitable transport network.

The geographic region covered by the RNS107may be divided into a number of cells, with a radio transceiver apparatus serving each cell. A radio transceiver apparatus is commonly referred to as a Node B in UMTS applications, but may also be referred to by those skilled in the art as a base station (BS), a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), or some other suitable terminology. For clarity, three Node Bs108are shown in each RNS107; however, the RNSs107may include any number of wireless Node Bs. The Node Bs108provide wireless access points to a core network104for any number of mobile apparatuses. Examples of a mobile apparatus include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a notebook, a netbook, a smartbook, a personal digital assistant (PDA), a satellite radio, a global positioning system (GPS) device, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, or any other similar functioning device. The mobile apparatus is commonly referred to as user equipment in UMTS applications, but may also be referred to by those skilled in the art as a mobile station (MS), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. In a UMTS system, the UE110may further include a USIM111, which contains a user's subscription information to a network. For illustrative purposes, one UE110is shown in communication with a number of the Node Bs108. The downlink (DL), also called the forward link, refers to the communication link from a Node B108to a UE110and the uplink (UL), also called the reverse link, refers to the communication link from a UE110to a Node B108.

The core network104can interface with one or more access networks, such as the UTRAN102. As shown, the core network104is a UMTS core network. However, as those skilled in the art will recognize, the various concepts presented throughout this disclosure may be implemented in a RAN, or other suitable access network, to provide UEs with access to types of core networks other than UMTS networks.

The illustrated UMTS core network104includes a circuit-switched (CS) domain and a packet-switched (PS) domain. Some of the circuit-switched elements are a Mobile services Switching Centre (MSC), a Visitor Location Register (VLR), and a Gateway MSC (GMSC). Packet-switched elements include a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN). Some network elements, like EIR, HLR, VLR, and AuC may be shared by both of the circuit-switched and packet-switched domains.

In the illustrated example, the core network104supports circuit-switched services with an MSC112and a GMSC114. In some applications, the GMSC114may be referred to as a media gateway (MGW). One or more RNCs, such as the RNC106, may be connected to the MSC112. The MSC112is an apparatus that controls call setup, call routing, and UE mobility functions. The MSC112also includes a visitor location register (VLR) that contains subscriber-related information for the duration that a UE is in the coverage area of the MSC112. The GMSC114provides a gateway through the MSC112for the UE to access a circuit-switched network116. The GMSC114includes a home location register (HLR)115containing subscriber data, such as the data reflecting the details of the services to which a particular user has subscribed. The HLR is also associated with an authentication center (AuC) that contains subscriber-specific authentication data. When a call is received for a particular UE, the GMSC114queries the HLR115to determine the UE's location and forwards the call to the particular MSC serving that location.

The illustrated core network104also supports packet-switched data services with a serving GPRS support node (SGSN)118and a gateway GPRS support node (GGSN)120. General Packet Radio Service (GPRS) is designed to provide packet-data services at speeds higher than those available with standard circuit-switched data services. The GGSN120provides a connection for the UTRAN102to a packet-based network122. The packet-based network122may be the Internet, a private data network, or some other suitable packet-based network. The primary function of the GGSN120is to provide the UEs110with packet-based network connectivity. Data packets may be transferred between the GGSN120and the UEs110through the SGSN118, which performs primarily the same functions in the packet-based domain as the MSC112performs in the circuit-switched domain.

In some aspects of the disclosure, the UE110may include a plurality of UICCs or SIM cards, each of which may run one or more universal subscriber identity module (USIM) applications. A USIM stores the subscriber's identity, and provides a user's subscription information to a network as well as performing other security and authentication roles. In one example, the illustrated UE110includes two USIMs111A and111B, but those of ordinary skill in the art will understand that this is illustrative in nature only, and a UE may include any suitable number of USIMs and UICCs. UEs such as the UE110having multiple USIMs can be referred to as multi-SIM or multiple standby devices, with one particular example with two USIMs being called Dual SIM Dual Standby (DSDS) device or dual-SIM device. In another example, a Triple SIM Triple Standby (TSTS) device has three USIMs allowing the UE to have three subscriptions. A DSDS device is capable of being in standby on two networks concurrently or simultaneously, where a transceiver or RF chain of the UE110is time-shared by two subscriptions on the respective networks. In this way, connections or calls may be established on either of the networks or subscriptions with a single DSDS device. In generally, a DSDS device can support an active call for only one subscription while the DSDS device is on standby for the other subscription. During standby, the DSDS device can receive, for example, paging information or other overhead information from one or more of the subscriptions.

As an illustrative example, the UE110is a DSDS device capable of maintaining communication for two subscriptions. Within the scope of the present disclosure, similar functionality may be achieved utilizing more than one radio access technology (RAT), wherein the UE simultaneously maintains two or more subscriptions on two or more different RATs. For example, such a UE may maintain one or more subscriptions on one or more of a GSM network, a UMTS network, an LTE network, a cdma2000 network, a Wi-MAX network, or any other suitable RAT. Within the present disclosure, DSDS devices, TSTS devices, multi-SIM or multiple standby devices, or any device capable of monitoring channels on two or more subscriptions on any one or any plural number of RATs, are generally referred to as a multi-SIM device in this specification.

On a multi-SIM UE110, some compromises are typical to allow sharing of the radio transceiver or RF resource for two or more separate user subscriptions. That is, the UE110may not be listening to all of the radio channels for each subscription at the same time, and thus, may miss paging messages on one subscription when engaged in a communication activity utilizing the other subscription. Many cellular network implementations do allow for broadcast information (such as paging messages) to be repeated a finite number of times over multiple cycles, but do not provide an effective mechanism for the subscriber devices to know what this repetition pattern might be. Thus, there remains a possibility that such broadcast information for one subscription might be missed by a multi-SIM UE engaged in a communication activity for a different subscription or channel. When the numbers of subscriptions increase to three or even more, paging performance may be worse because less time will be available for monitoring the paging channels on each of the subscriptions using a tune-away procedure. During a tune-away procedure, the UE110reconfigures (e.g., retunes) its radio transceiver such that it can monitor channels from the secondary subscription while maintaining the connection with the primary subscription. However, performance of the primary subscription may be affected if the tune-away is overused. In other examples, the UE110may perform the tune-away procedure such that it can monitor channels for the primary subscription while performing a signaling procedure for the secondary subscription.

The UTRAN102is one example of a RAN that may be utilized in accordance with the present disclosure. Referring toFIG. 2, by way of example and without limitation, a simplified schematic illustration of a RAN200in a UTRAN architecture is illustrated. The system includes multiple cellular regions (cells), including cells202,204, and206, each of which may include one or more sectors. Cells may be defined geographically (e.g., by coverage area) and/or may be defined in accordance with a frequency, scrambling code, etc. That is, the illustrated geographically-defined cells202,204, and206may each be further divided into a plurality of cells, e.g., by utilizing different scrambling codes. For example, cell204amay utilize a first scrambling code, and cell204b, while in the same geographic region and served by the same Node B244, may be distinguished by utilizing a second scrambling code.

In a cell that is divided into sectors, the multiple sectors within a cell can be formed by groups of antennas with each antenna responsible for communication with UEs in a portion of the cell. For example, in cell202, antenna groups212,214, and216may each correspond to a different sector. In cell204, antenna groups218,220, and222may each correspond to a different sector. In cell206, antenna groups224,226, and228may each correspond to a different sector.

The cells202,204, and206may include several UEs that may be in communication with one or more sectors of each cell202,204, or206. For example, UEs230and232may be in communication with Node B242, UEs234and236may be in communication with Node B244, and UEs238and240may be in communication with Node B246. Here, each Node B242,244, and246may be configured to provide an access point to a core network104(seeFIG. 1) for all the UEs230,232,234,236,238, and240in the respective cells202,204, and206. Any of the UEs inFIG. 2may be a multi-SIM UE.

During a call with a source cell, or at any other time, the UE236may monitor various parameters of the source cell as well as various parameters of neighboring cells. Further, depending on the quality of these parameters, the UE236may maintain communication with one or more of the neighboring cells. During this time, the UE236may maintain an Active Set, that is, a list of cells to which the UE236is simultaneously connected (i.e., the UTRAN cells that are currently assigning a downlink dedicated physical channel DPCH or fractional downlink dedicated physical channel F-DPCH to the UE236may constitute the Active Set).

In a wireless telecommunication system, the communication protocol architecture may take on various forms depending on the particular application. For example, in a 3GPP UMTS system, the signaling protocol stack is divided into a Non-Access Stratum (NAS) and an Access Stratum (AS). The NAS provides the upper layers, for signaling between the UE110and the core network104(referring toFIG. 1), and may include circuit switched and packet switched protocols. The AS provides the lower layers, for signaling between the UTRAN102and the UE110, and may include a user plane and a control plane. Here, the user plane or data plane carries user traffic, while the control plane carries control information (i.e., signaling).

Turning toFIG. 3, the AS is shown with three layers: Layer 1 (L1), Layer 2 (L2), and Layer 3 (L3). Layer 1 is the lowest layer and implements various physical layer signal processing functions. Layer 1 will be referred to herein as the physical layer306. The data link layer, called Layer 2308, is above the physical layer306and is responsible for the link between the UE110and Node B108over the physical layer306.

At Layer 3, the radio resource control (RRC) layer316handles the control plane signaling between the UE110and the Node B108. RRC layer316includes a number of functional entities for routing higher layer messages, handling broadcasting and paging functions, establishing and configuring radio bearers, etc. The RRC layer316may also perform a signaling procedure with a peer RRC entity of the network.

In the illustrated air interface, the L2 layer308is split into sublayers. In the control plane, the L2 layer308includes two sublayers: a medium access control (MAC) sublayer310and a radio link control (RLC) sublayer312. In the user plane, the L2 layer308additionally includes a packet data convergence protocol (PDCP) sublayer314. Although not shown, the UE may have several upper layers above the L2 layer308including a network layer (e.g., IP layer) that is terminated at a PDN gateway on the network side and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc.).

The PDCP sublayer314provides multiplexing between different radio bearers and logical channels. The PDCP sublayer314also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between Node Bs.

The RLC sublayer312generally supports an acknowledged mode (AM) (where an acknowledgment and retransmission process may be used for error correction), an unacknowledged mode (UM), and a transparent mode for data transfers, and provides segmentation and reassembly of upper layer data packets and reordering of data packets to compensate for out-of-order reception due to a hybrid automatic repeat request (HARQ) at the MAC layer. In the acknowledged mode, RLC peer entities such as an RNC and a UE may exchange various RLC protocol data units (PDUs) including RLC Data PDUs, RLC Status PDUs, and RLC Reset PDUs, among others. In the present disclosure, the term “packet” may refer to any RLC PDU exchanged between RLC peer entities. The MAC sublayer310provides multiplexing between logical and transport channels. The MAC sublayer310is also responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer310is also responsible for HARQ operations.

A multi-SIM UE110can support multiple radio protocol architectures including the UMTS protocol architecture ofFIG. 3and other protocol architectures known in the art. In various aspects of the disclosure, the multi-SIM UE110can also support the radio protocol architecture of an LTE network, a cdma2000 network, a Wi-MAX network, or any other suitable RAT.

FIG. 4is a diagram illustrating a multi-SIM UE400capable of utilizing a primary subscription and one or more secondary subscriptions using a tune-away procedure, in accordance with an aspect of the disclosure. The UE400may be any of the UEs illustrated inFIGS. 1,2,5,7,8, and/or12. The UE400includes a number of components or blocks that may be implemented in hardware, software, firmware, and/or a combination thereof. The UE400has a primary subscription block402(e.g., a first subscription component) and a secondary subscription block404(e.g., a second subscription component). The primary subscription block402is for communication with a first network406associated with a primary subscription. The secondary subscription block404is for communication with one or more second networks408associated with corresponding secondary subscriptions. The terms “primary” and “secondary” used in this context is for identification of the different subscriptions, but not implying any ranking or preference among the subscriptions.

In one aspect of the disclosure, the UE400can use the same radio frequency (RF) chain410to communicate with the first network406and second networks408using a suitable tune-away procedure. The UE400also includes a tune-away control block412(e.g., a tune-away control component), together with other blocks, for performing or controlling a tune-away procedure between the primary and secondary subscriptions. While the UE400is active (e.g., engaged in a voice or data call, or signaling procedure) for the primary subscription, the UE400may need to tune away to the secondary subscription at certain occasions. In one example, the UE400may need to tune away to the secondary subscription to receive paging messages, for example, the Paging Indicators (PIs) for a Mobile Terminated (MT) call of the second network408. In one example, the UE400may monitor a Paging Channel (PCH)416, which is always transmitted over the entire cell. The transmission of the PCH416is associated with the transmission of physical-layer generated Paging Indicators. This process of tuning-away from the primary subscription for reading the paging information on the secondary subscription is generally referred as tune-away (e.g., DSDS tune-away for a dual SIM UE or multi-SIM tune-away for a multi-SIM UE).

If the UE400goes through the tune-away process while there is an ongoing signaling procedure for the primary subscription, it is possible that the UE400may miss the signaling messages or an associated Layer 2 acknowledgment (ACK) for the signaling messages of the primary subscription. For example, the signaling messages may include an SRB message418or data packets/PDUs carried on an SRB. The UE400may have an SRB message processing block420(e.g., a message processing component) that can process SRB messages or PDUs of the SRB messages. Referring toFIG. 5, an SRB500is established between a UE502and an access network (AN)504, and a Radio Access Bearer (RAB)506is established between the UE502and a code network (CN)508. The SRB500can be used to deliver SRB signaling messages, for example, to perform a handover, reconfiguration, release, etc. In one example, the UE502may be the same as the UE400. Any failure of the signaling messages (e.g., SRB messages) is not desirable from the performance standpoint of the primary subscription. Also, any failure of signaling procedures might result in an undesirable call drop for the primary subscription.

During connection establishment, an RRC Connection Setup procedure establishes one or more SRBs. The SRBs are then used to send all subsequent signaling messages to start the desired service and establish the radio bearers (RBs) for the service. A procedure involving these exchanges of SRB messages is generally referred to as a signaling procedure. In some aspects of the disclosure, a signaling procedure refers to the information exchange concerning the establishment and control of communication between a UE and a network. Establishment of the radio bearers is achieved using a radio bearer (RB) Setup procedure. A major part of the control signaling between a UE and a UTRAN (or an access network) is RRC signaling. SRBs are used in the control plane for RRC signaling. RRC messages (SRB messages) carry the parameters used to set up, modify and release layer 2 and layer 1 protocol entities. RRC messages also carry in their payload higher layer signaling (e.g., mobility management (MM), connection management (CM), session management (SM), etc.). In addition, the mobility of a UE in the connected mode is controlled by RRC signaling (measurements, handovers, cell updates, etc.).

SRB messages are generally given higher priority in order to meet the performance requirements for the SRB procedures in terms of (N1, N2) parameters specified in the 3GPP Technical Specification (TS) 25.331, RRC Protocol Specification, section 13.5, version 12.1.0, which is incorporated herein by reference. To avoid or reduce performance degradation of SRB signaling for the primary subscription, a multi-SIM UE should avoid tune-away or relinquishing its RF resources (e.g., RF chain410) so as to access the secondary subscriptions in certain conditions.

FIG. 6is a diagram illustrating a method600for performing tune-away during an SRB signaling procedure according to an aspect of the disclosure. In one example, the method600may be performed using any of the UEs illustrated inFIGS. 1,2,4,5,7,8, and/or12such as the UE400. At block602, if an SRB message is partly received in the downlink (DL) of the primary subscription, the UE will avoid tune-away. For example, the SRB message may be an RRC Connection Reconfiguration message of which one or more PDUs have been received. At block604, if an SRB response for a received SRB message is pending transmission in the uplink (UL), the UE will avoid tune-away. For example, the SRB response may be an RRC Connection Reconfiguration Complete message. At block606, if the UE has not yet received an L2 acknowledgement (ACK) at the peer RLC level for an SRB response sent in the uplink, the UE will avoid tune-away. Otherwise, at block608, the UE can tune away to the secondary subscription to receive paging messages. In some aspects of the disclosure, the UE may perform some or all of the operations of blocks602,604, and606in any suitable orders, not limited to the particular order illustrated inFIG. 6. In one aspect of the disclosure, the method600may be used when the SRB signaling procedure involves signaling critical messages.

With the growing number of SIMs in a UE (e.g., 3 or more SIMs), paging performance becomes very critical in addition to other subscription activities. In some cases, heavy network usage of some SRB messages, which are not vital or critical to maintaining the signaling connection for the primary subscription, may degrade paging performance and increase call drop on the secondary subscription. For example, the network may generate large amount of signaling non-critical messages such as Measurement Control and Measurement Report messages that can prevent the UE from performing tune-away according to the three conditions for avoiding tune-away ofFIG. 6. Therefore, the UE will have less opportunity to receive paging messages from the other subscription using tune-away.

FIG. 7is a block diagram illustrating an example of a hardware implementation for an apparatus700employing a processing system701. In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with a processing system701that includes one or more processors704. For example, in an aspect of the disclosure, the UEs ofFIGS. 1,2,4,5,8, and/or12may be implemented with the apparatus700. Examples of the processors704include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware specifically configured to perform the various functions, methods, and procedures described throughout this disclosure.

In this example, the processing system701may be implemented with a bus architecture, represented generally by the bus702. The bus702may include any number of interconnecting buses and bridges depending on the specific application of the processing system701and the overall design constraints. The bus702links together various circuits or components including one or more processors (represented generally by the processor704), a memory705, computer-readable media (represented generally by the computer-readable medium706), a tune-away block714, and one or more SIMs or UICCs711A and711B. Each UICC contains one or more USIM applications. The tune-away block714may include some or all of the blocks or components of the UE400ofFIG. 4. The bus702may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further. A bus interface708provides an interface between the bus702and a transceiver710. The transceiver710provides a means for communicating with various other apparatus over a transmission medium. For example, the transceiver710may be used to communicate with multiple networks associated with different subscriptions during a tune-away procedure described in FIGS.6and8-12.

In some examples, even though each UICC (711A and711B) may be associated with different subscriptions or networks, the UICCs can share a single transceiver710to communicate with the different subscriptions using a tune-away procedure. While the examples detailed herein relate to UEs that utilize a single transceiver710and methods for performing the below-described tune-away procedure utilizing a shared transceiver, the broad concepts described herein may also be applicable to devices having two or more transceivers or RF chains.

Depending upon the nature of the apparatus, a user interface712(e.g., keypad, display, speaker, microphone, joystick, touchscreen, touchpad) may also be provided. The processor704is responsible for managing the bus702and general processing, including the execution of software stored on the computer-readable medium706. The software may include a tune-away software707that when executed for example by the processor704and/or tune-away block714, causes the processing system701to perform the various functions described in FIGS.6and8-12for any particular apparatus. The computer-readable medium706may also be used for storing data that is manipulated by the processor704when executing software.

In some aspects of the disclosure, a UE can simultaneously or concurrently perform two different communication activities, including but not limited to connecting with two different networks, two different subscriptions within the same network, or two cells in a cellular network. For example, the UE may be any of the UEs illustrated inFIGS. 1,2,4,5,7,8, and/or12. Particularly beneficial would be a UE enabled to continue to be engaged in ongoing communication activities (e.g., a signaling procedure) for one subscription, while simultaneously performing other communication activities for another subscription, such as receiving paging messages, performing SMS messaging, or receiving other information for a different subscription or from a different cell.

FIG. 8is a message flow diagram illustrating an RRC signaling procedure800between a UE802and a first UTRAN804. In one aspect of the disclosure, the UE802may be any of the UEs illustrated inFIGS. 1,2,4,5,7, and/or12, and the first UTRAN804may be associated with a primary subscription. In general, RRC signaling procedures involve various RRC messages including, for example, signaling message request/setup/setup complete and reconfigure/reconfigure complete. Referring toFIG. 8, in an RRC connection establishment procedure (a signaling procedure), the UE802transmits an RRC Connection Request message806to the first UTRAN804, and the first UTRAN returns an RRC Connection Setup message808that contains configuration information for setting up an SRB (e.g., SRB500ofFIG. 5). The RRC connection establishment procedure is one example of SRB signaling procedures. Then, the UE802transmits an RRC Connection Setup Complete message810that confirms the successful completion of the RRC connection establishment procedure.

When the RRC connection establishment procedure is ongoing, a second UTRAN812associated with a secondary subscription may send one or more paging messages814to the UE802. However, a conventional UE would not tune away under certain conditions and may miss the paging messages. For example, in the conventional multi-SIM design, a UE is not allowed to tune away to the secondary subscription while the RRC connection establishment procedure is ongoing until a layer 2 RLC ACK is received by the UE for the RRC Connection Setup Complete message810. Because these RRC message exchange procedures can span over a few hundreds of milliseconds, the number of paging message misses might be undesirably high for the other subscription and might result in degraded mobile terminated (MT) call performance on the secondary subscription. Furthermore, some signaling procedures do not have very specific time requirements; therefore, during heavy network loading conditions, the signaling procedures may take an undesirably long time to complete, thus resulting in more MT call performance degradation.

Some SRB signaling procedures are used for controlling cell measurements. For example, in a cell measurement signaling procedure, the first UTRAN804(e.g., an RNC) may send a Measurement Control message816to the UE802. Based on the information of the Measurement Control message816, the UE802performs the requested measurements and sends a Measurement Report message818back to the first UTRAN804. A conventional UE may not tune away while the cell measurement signaling procedure is ongoing (i.e., not completed), and may miss a paging message814from the second UTRAN812. Therefore, extensive usage of the measurement control and report messages for the primary subscription may block multiple paging occasions for the secondary subscription.

Thus, various aspects of the present disclosure provide for an improved tune-away procedure that can enhance multi-SIM performance of a UE, for example, in the above-described scenarios. That is, one or more aspects of the disclosure are directed to an improved tune-away scheme, such that the UE may tune away from a primary subscription to improve paging performance of one or more secondary subscriptions when certain signaling procedures involving signaling non-critical SRB messages are ongoing with the primary subscription. Non-limiting examples of signaling non-critical messages include the Measurement Control message816and Measurement Report message818ofFIG. 8.

One aspect of the tune-away procedures disclosed herein lies in how it enables a UE to use a shared transceiver or RF resource to perform a tune-away procedure for two or more subscriptions in an efficient way, thus improving multi-SIM multi-standby performance. The UE may be any of the UEs illustrated inFIGS. 1,2,4,5,7,8, and/or12. To provide a straightforward understanding of various aspects of the disclosure, examples are provided below. As described below, a multi-SIM UE may periodically tune away from a primary subscription and receive paging messages from a secondary subscription with the same transceiver without substantially affecting an ongoing signaling procedure with the primary subscription. In an aspect of the disclosure, the UE skips or avoids tuning away from the primary subscription only if the ongoing SRB message(s) involved is a signaling critical message. Therefore, the UE can tune away to the secondary subscription more often to improve paging performance while a signaling procedure involving non-critical SRB messages is still ongoing for the primary subscription.

FIG. 9is a diagram illustrating a tune-away method900operable at a multi-SIM UE in accordance with an aspect of the disclosure. In one example, the method900may be performed at any of the UEs illustrated inFIGS. 1,2,4,5,7,8, and/or12such as the UE400. At block902, the UE400performs a signaling procedure for a first subscription. During the signaling procedure, the UE400receives at least one PDU of an SRB message from a first network406associated with the first subscription. For example, the UE400may utilize the primary subscription block402to perform the signaling procedure. In one example, the SRB message may be any of the RRC messages ofFIG. 8. At block904, the UE400determines a message type of the SRB message based on the received at least one PDU. The SRB message types are described in the 3GPP TS 25.331, Radio Resource Control (RRC); Protocol specification (Release 12), which is incorporated herein by reference. For example, some of the SRB message types defined in 3GPP TS 25.331 are illustrated in Table 1 below. For example, the UE400may utilize the SRB message processing block420to process the PDU in order to determine the type of the SRB message. At block906, if the message type indicates that the SRB message includes a signaling non-critical message, the UE400can perform a tune-away procedure for a second network408associated with a second subscription, while the signaling procedure is ongoing for the first subscription. For example, the UE400may utilize the tune-away control block412to perform a tune away procedure to the second network408to receive data (e.g., paging messages) from the second network, while the SRB signaling procedure is still ongoing with the first network406. However, if the message type indicates that the SRB message includes a signaling critical message, the UE400avoids tune-away while the signaling procedure involving such SRB message is ongoing (i.e., not completed).

By way of examples and not limitation, signaling critical SRB messages include a radio bearer reconfiguration message, a transport channel reconfiguration message, a physical channel reconfiguration message, an active set update message, a cell update message, a UTRAN registration area (URA) update message, etc. Some non-limiting examples of the signaling non-critical SRB messages include measurement control messages, measurement report messages, etc.

FIG. 10is a flow chart illustrating a method1000for determining the type of an SRB message based on its PDU in accordance with an aspect of the disclosure. In one example, the method1000may be performed by any of the UEs illustrated inFIGS. 1,2,4,5,7,8, and/or12. For example, a UE400may utilize the SRB message processing block420ofFIG. 4to perform the method1000. At block1002, the UE400parses or analyzes the received one or more PDUs of an SRB message, which may include an Abstract Syntax Notation 1 (ASN.1) encoded RRC DL-DCCH-Message (Downlink Dedicated Control Channel (DCCH) message). See 3GPP TS 25.331 for more information. The RRC entity of the UE is aware of the fixed offset where the ASN.1 message type indication is present in the received PDU. With this information, at block1004, the UE400locates the bit field of the PDU corresponding to the SRB message type. Then at block1006, the UE400can determine whether the SRB message is a signaling critical SRB message or a signaling non-critical SRB message based on the SRB message type. For example, the RLC entity of the UE can check the received PDU message to determine what SRB message is being received and indicate this to the RRC entity. Some examples of the SRB message types are shown in Table 1 below.

FIG. 11is a flow chart illustrating a tune-away procedure1100operable at a multi-SIM UE in accordance with an aspect of the disclosure. In one example, the tune-away procedure1100may be performed by any of the UEs illustrated inFIGS. 1,2,4,5,7,8, and/or12such as the UE400. For example, the tune-away procedure1100may be performed at block906ofFIG. 9. It is assumed that the UE400already received at least one PDU of an SRB message from a primary subscription, and the UE400can determine the type of the SRB message using for example the method1000ofFIG. 10. If the SRB message is a signaling critical message, the procedure1100continues to block1102; otherwise, the procedure continues to block1104. At block1102, the UE400may perform a signaling critical SRB tune-away procedure similar to the method600ofFIG. 6according to one example. Referring toFIG. 12, the UE400may be performing a signaling procedure1202involving a signaling non critical SRB message with a first network406associated with a primary subscription. If the SRB message is not a signaling critical message, the UE400may perform a tune-away procedure1204for a second network408associated with a secondary subscription in certain conditions while the SRB signaling procedure1202is still ongoing.

Referring back toFIG. 11, at block1104, the UE400can tune away if a signaling non-critical SRB is partly received in the downlink (DL) for the primary subscription. At block1106, the UE400can tune away if the SRB response sent in the uplink (UL) has not yet received an L2 ACK, and the number of retransmission of the L2 ACK is less than a predetermined number. For example, the predetermined number may be half of the maximum retransmission number, which may be determined by the network. Thus, the UE400will avoid tune-away if the number of retransmission of the L2 ACK is equal to or greater than the predetermined number. Blocks1104and1106are only some examples of the improved tune-away procedure1204, which may be applicable with other suitable signaling non-critical SRB messages. Furthermore, the sequence of execution of the various procedures, steps, and blocks ofFIG. 11may be modified in other aspects of the disclosure. According to the procedure1100, a UE may improve paging performance with the secondary subscription without significantly impacting SRB signaling on the primary subscription.

Several aspects of a telecommunications system have been presented with reference to a UMTS system. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures and communication standards.