ACHIEVING DUAL SIM DUAL ACTIVE OPERATION IN AN LTE + LTE DEVICE BY DOWNGRADING USER EQUIPMENT CATEGORY TO 1 FOR ONE SIM

A method for performing a dedicated data subscription (DDS) switch on a multi subscriber identity module multi-active (MSMA) mobile communication device includes: initiating a DDS switch from a first subscription to a second subscription; determining whether a first communication network associated with the first subscription supports user equipment (UE) capability update via a tracking area update (TAU) procedure; in response to determining that the first communication network supports UE capability update via a TAU procedure, initiating a TAU procedure on the first subscription with the first communication network; and reporting a UE category 1 capability to the first communication network on the first subscription for the mobile communication device during the TAU procedure on the first subscription.

BACKGROUND

An incoming Voice over Long Term Evolution (VoLTE) call to a mobile communication device is indicated by a page from a communication network. Upon receiving the page, the mobile communication may set up a packet switched (PS) connection and may receive a SIP_INVITE indicating a VoLTE call request. To decode a SIP_INVITE, the mobile communication device switches from an idle state to a connected/traffic state. A user equipment (UE) category 4 dual subscriber identity module (SIM) dual active (DSDA) mobile communication device having two LTE subscriptions with VoLTE enabled may use one receive (RX) chain to decode the SIP_INVITE, but two RX chains to enter traffic mode to receive the VoLTE call on one subscription. However, a category 1 LTE device uses one RX chain to decode an incoming data packet successfully.

With limited RX chains it may not be possible for the UE category 4 DSDA mobile communication device to concurrently support a second VoLTE call on a second subscription. For example, a DSDA mobile communication device may have two transmit (TX) chains and three RX chains, and a first LTE subscription on a first SIM may be a dedicated data subscription (DDS). With an active data call on the first SIM, two RX chains and one TX chain may be assigned to the first LTE subscription on the first SIM leaving one RX chain and one TX chain left for the second subscription.

If a page for an incoming VoLTE call is received by a second LTE subscription on the second SIM, the subsequent SIP_INVITE may be decoded using the one remaining RX chain. However, two RX chains may be used by the UE category 4 DSDA mobile communication device to enter traffic mode to receive the VoLTE call. Since only one RX chain is available for the second subscription, the mobile communication device cannot enter traffic mode and therefore cannot achieve DSDA behavior (i.e., maintain calls on both subscriptions).

SUMMARY

Apparatuses and methods for achieving DSDA operation for a mobile communication device by downgrading the UE category to 1 are provided.

According to various aspects there is provided a method for performing a dedicated data subscription (DDS) switch on a multi subscriber identity module multi-active (MSMA) mobile communication device. In some aspects, the method may include: initiating a DDS switch from a first subscription to a second subscription; determining whether a first communication network associated with the first subscription supports user equipment (UE) capability update via a tracking area update (TAU) procedure; in response to determining that the first communication network supports UE capability update via a TAU procedure, initiating a TAU procedure on the first subscription with the first communication network; and reporting a UE category 1 capability to the first communication network on the first subscription for the mobile communication device during the TAU procedure on the first subscription.

According to various aspects there is provided a multi subscriber identity module multi-active (MSMA) mobile communication device having a first long term evolution (LTE) subscription and a second LTE subscription. In some aspects, the mobile communication device may include: a plurality of receive (RX) chains; a memory operably connected to the plurality of RX chains; and a control unit operably connected to the plurality of RX chains and the memory.

The control unit may be configured to: initiate a DDS switch from the first LTE subscription to the second LTE subscription; determine whether a first communication network associated with the first LTE subscription supports user equipment (UE) capability update via a tracking area update (TAU) procedure; in response to determining that the first communication network supports UE capability update via a TAU procedure, initiate a TAU procedure on the first LTE subscription with the first communication network; and report a UE category 1 capability to the first communication network on the first LTE subscription for the mobile communication device during the TAU procedure on the first LTE subscription

According to various aspects there is provided a method for receiving a Voice over Long Term Evolution (VoLTE) call on a user equipment (UE) multi subscriber identity module multi-active (MSMA) mobile communication device having less than four receive chains and a dedicated data subscription (DDS) set to a first subscription. In some aspects, the method may include: entering traffic mode by the first subscription associated with a first communication network; reporting a rank indicator equal to one for the mobile communication device to the first communication network on the first subscription without determining channel conditions; determining channel conditions for the first subscription based on one or more measured parameters; and in response determining that the one or more measured parameters are equal to or greater than a threshold value, assigning one receive chain to the first subscription

Other features and advantages should be apparent from the following description which illustrates by way of example aspects of the various teachings of the disclosure.

DETAILED DESCRIPTION

While certain embodiments are described, these embodiments are presented by way of example, and are not intended to limit the scope of protection. The apparatuses, methods, and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and changes in the form of the example methods and systems described herein may be made without departing from the scope of protection.

FIG. 1Ais a block diagram illustrating a mobile communication device100according to various embodiments. As illustrated inFIG. 1, the mobile communication device100may include a control unit110, a first communication unit120, a second communication unit123, a third communication unit126, a first antenna130, a second antenna132, a third antenna134, a first subscriber identity module (SIM)150, a second SIM155, a user interface device170, and a memory180.

The mobile communication device100may be, for example but not limited to, a mobile telephone, smartphone, tablet, computer, etc., capable of communications with one or more wireless networks. One of ordinary skill in the art will appreciate that the mobile communication device100may include one or more transceivers (communication units) and may interface with one or more antennas without departing from the scope of protection. The mobile communication device100may be a UE category 4 mobile communication device.

The first communication unit120may include, for example, but not limited to, a first radio frequency (RF) module121. The first RF module121may include, for example, but not limited to a first transceiver122. A first RF chain135may include, for example, but not limited to the first antenna130and the first RF module121. A first RX chain140may include a receiver portion (not shown) of the first transceiver122, the first RF module121, and the first antenna130.

The second communication unit123may include, for example, but not limited to, a second RF module124. The second RF module124may include, for example, but not limited to a second transceiver125. A second RF chain137may include, for example, but not limited to the second antenna132and the second RF module124. A second RX chain142may include a receiver portion (not shown) of the second transceiver125, the second RF module124, and the second antenna132.

The third communication unit126may include, for example, but not limited to, a third RF module127. The third RF module127may include, for example, but not limited to a receiver128. A third RF chain139may include, for example, but not limited to the third antenna134and the third RF module127. A third RX chain144may include the receiver128, the third RF module127, and the third antenna134.

One of ordinary skill in the art will appreciate that embodiments of the mobile communication device100may include more or less than three antennas without departing from the scope of protection.

A SIM (for example the first SIM150and/or the second SIM155) in various embodiments may be a universal integrated circuit card (UICC) that is configured with SIM and/or universal SIM (USIM) applications, enabling access to global system for mobile communications (GSM) and/or universal mobile telecommunications system (UMTS) networks. The UICC may also provide storage for a phone book and other applications. Alternatively, in a code division multiple access (CDMA) network, a SIM may be a UICC removable user identity module (R-UIM) or a CDMA subscriber identity module (CSIM) on a card. A SIM card may have a CPU, ROM, RAM, EEPROM and I/O circuits. An integrated circuit card identity (ICCID) SIM serial number may be printed on the SIM card for identification. However, a SIM may be implemented within a portion of memory of the mobile communication device100, and thus need not be a separate or removable circuit, chip, or card.

A SIM used in various embodiments may store user account information, an international mobile subscriber identity (IMSI), a set of SIM application toolkit (SAT) commands, and other network provisioning information, as well as provide storage space for phone book database of the user's contacts. As part of the network provisioning information, a SIM may store home identifiers (e.g., a system identification number (SID)/network identification number (NID) pair, a home public land mobile network (HPLMN) code, etc.) to indicate the SIM card network operator provider.

The first SIM150may associate the first communication unit120with a first subscription (Sub1)192associated with a first radio access technology (RAT) on a first communication network190and the second SIM155may associate the second communication unit123with a second subscription (Sub2)197associated with a second RAT on a second communication network195.

For convenience, the various embodiments are described in terms of DSDA mobile communication devices. However, one of ordinary skill in the art will appreciate that the various embodiments may be extended to Multi-SIM Multi-Active (MSMA) mobile communication devices without departing from the scope of protection.

The first communication network190and the second communication network195may be operated by the same or different service providers, and/or may support the same or different RATs, for example, but not limited to, GSM, CDMA, wideband CDMA (WCDMA), and long term evolution (LTE).

The user interface device170may include an input device172, for example, but not limited to a keyboard, touch panel, or other human interface device, and a display device174, for example, but not limited to, a liquid crystal display (LCD), light emitting diode (LED) display, or other video display. One of ordinary skill in the art will appreciate that other input and display devices may be used without departing from the scope of the various embodiments.

The control unit110may be configured to control overall operation of the mobile communication device100including control of the first, second, and third communication units120,123,126, the user interface device170, and the memory180. The control unit110may be a programmable device, for example, but not limited to, a microprocessor (e.g., general-purpose processor, baseband modem processor, etc.) or microcontroller.

The memory180may be configured to store operating systems and/or application programs for operation of the mobile communication device100that are executed by the control unit110, as well as to store application data and user data.

FIG. 1Bis a diagram illustrating a network environment105for various embodiments. Referring toFIGS. 1A and 1B, a mobile communication device100may be configured to communicate with a first communication network190on Sub192and a second communication network195on Sub2197. One of ordinary skill in the art will appreciate that the mobile communication device may configured to communicate with more than two communication networks and may communicate on more than two subscriptions without departing from the scope of protection.

The first communication network190and the second communication network195may implement the same or different radio RATs. For example, the first communication network190may be LTE network and Sub1192may be an LTE subscription. The second communication network195may also be an LTE network and Sub2197may be an LTE subscription. In various embodiments, Voice over LTE (VoLTE) may be enabled on both Sub1192and Sub2197.

The first communication network190may include one or more base transceiver stations (BTSs) including, for example, but not limited to, a first BTS193. The second communication network195may also include one or more BTSs, including, for example, but not limited to, a second BTS198. A person having ordinary skill in the art will appreciate that the network environment105may include any number of communication networks, mobile communication devices, and BTSs without departing from the scope of the various embodiments.

The mobile communication device100may attempt to acquire the first communication network190and camp on the first BTS193. The mobile communication device100may also attempt to acquire the second communication network195and camp on the second BTS198. A person having ordinary skill in the art will appreciate that the acquisition of the first communication network190performed on Sub1192may be independent of the acquisition of the second communication network195performed on Sub2197. Furthermore, the mobile communication device100may attempt to acquire the first communication network190on Sub1192and the second communication network195on Sub2197.

A UE category 4 LTE mobile communication device may decode a SIP_INVITE using one RX chain, but may decode incoming data packets (e.g., receive an incoming VoLTE call) using two RX chains. With a limited number of RX chains, it may not be possible for a UE category 4 LTE mobile communication device to support concurrent VoLTE calls on more than one subscription. On the other hand, a UE category 1 LTE mobile communication device may decode a SIP_INVITE and decode incoming data packets (i.e., inter-into traffic mode) using one RX chain.

In various examples, for a DSDA mobile communication device (e.g., the mobile communication device100) one subscription may be selected as a DDS and assigned two RX chains (i.e., UE category 4) while the other subscription may be downgraded to a UE category 1 and assigned one RX chain. By lowering the category of the non-DDS LTE subscription, one RX chain may be provided for VoLTE on the non-DDS subscription and two RX chains may be provided for the data call on the DDS subscription. Thus, if the category of the second SIM (e.g., the second SIM155) LTE stack can be lowered, then the second subscription (e.g., Sub2197) can enter the traffic state using one RX chain and decode the SIP_INVITE in the traffic state and achieve DSDA behavior.

In one example, the category of the second subscription (e.g., Sub2197) on the second SIM (e.g., the second SIM155) is downgraded when the DDS is set to the first SIM (e.g., the first SIM150) or vice-versa. Since a VoLTE call does not typically use high data rates, there will be a limited effect on the second SIM (e.g., the second SIM155). Two methods may be used to downgrade a SIM to category 1: 1) the UE may use a TAU procedure to update the new UE category to the communication network (e.g., the first communication network190or the second communication network195), and 2) the UE may detach from the communication network and attach again to the communication network to update the new UE category.

FIG. 2is a sequence diagram illustrating a dedicated data subscription (DDS) switch200according to various examples and more particularly to the first method of lowering a category discussed above. Referring toFIGS. 1A-2, at block205, Sub1192may be the DDS and may have initially reported a UE category 4. At block210, Sub2197may also have initially reported a UE category 4. At block215, the mobile communication device100may receive a DDS switch instruction to switch the DDS from Sub1192to Sub2197. For example, a user may manually provide a DDS switch instruction. Alternatively, the DDS switch may be initiated by, for example, but not limited to, reception of a multimedia messaging service (MMS) message indication.

After receiving the DDS switch instruction, at block220the mobile communication device100may downgrade Sub1192to UE category 1. At block225the mobile communication device100may initiate a tracking area update (TAU) procedure on Sub1192by issuing a TAU request to the first communication network190. At block230the first communication network190may respond with a UE capability inquiry. At block235the mobile communication device100may respond on Sub1192with a UE category equal to 1, thereby downgrading Sub1192to UE category 1. In response, at block240the first communication network190may set the radio resource control (RRC) connection to transmission mode1(TM1). At block245the mobile communication device may send an RRC connection reconfiguration complete message on Sub1192to the first communication network190thereby completing the TAU procedure on Sub1192.

Similarly, at block250the mobile communication device100may upgrade (or maintain) Sub2197to UE category 4. At block255the mobile communication device100may initiate a tracking area update (TAU) procedure on Sub2197by issuing a TAU request to the second communication network195. At block260the second communication network195may respond with a UE capability inquiry. At block265the mobile communication device100may respond on Sub2197with a UE category equal to 4, thereby upgrading (or maintaining) Sub2197to UE category 4. In response, at block270the second communication network195may set the RRC connection to any transmission mode (TM) (e.g., TM1-TM4). At block275the mobile communication device may send an RRC connection reconfiguration complete message on Sub2197to the second communication network195thereby completing the TAU procedure on Sub2197. Accordingly, at block280Sub1192may report a UE category equal to 1 and at block285Sub2197may be the DDS and may report a UE category equal to 4.

FIG. 3is a flowchart of a method300for performing a dedicated data subscription (DDS) switch on a UE category 4 multi subscriber identity module multi-active (MSMA) mobile communication device according to various and more particularly to the both methods of lowering a category discussed above. Referring toFIGS. 1A, 1B, and 3, at block310the mobile communication device100may initiate a DDS switch from Sub1192to Sub2197. For example, a user may manually provide a DDS switch instruction. Alternatively, the DDS switch may be initiated by, for example, but not limited to, an instruction from the control unit110after reception by the second communication unit123of a multimedia messaging service (MMS) message indication on Sub2197.

At block315the control unit110may determine if the first communication network190(i.e., NTWK1) supports UE capability information on TAU. In response to determining that the first communication network190supports UE capability information on TAU (315-Y), at block320the control unit110may initiate a TAU procedure for Sub1192. At block325, during the TAU procedure the control unit110may report a UE capability for Sub1192equal to UE category 1 to the first communication network190.

In response to determining that the first communication network190does not support UE capability information on TAU (315-N), at block330the control unit110may initiate a detach/re-attach procedure for Sub1192. At block335, during a re-attach portion of the detach/re-attach procedure the control unit110may report a UE capability equal to UE category 1 for Sub1192to the first communication network190. At block340, the control unit110may assign one RX chain (e.g., the first RX chain140) to Sub1192. With the mobile communication device100configured as UE category 1 for Sub1192, the mobile communication device100may be capable of receiving and decoding a SIP_INVITE and entering traffic mode to receive a VoLTE call using one RX chain (e.g., the first RX chain140) on Sub1192.

At block345the control unit110may determine if the second communication network195(i.e., NTWK2) supports UE capability information on TAU. In response to determining that the second communication network195supports UE capability information on TAU (345-Y), at block350the control unit110may initiate a TAU procedure for Sub2197. At block355, during the TAU procedure the control unit110may report a UE capability for Sub1197equal to UE category 4 to the second communication network195.

In response to determining that the second communication network195does not support UE capability information on TAU (345-N), at block360the control unit110may initiate a detach/re-attach procedure for Sub2197. At block365, during a re-attach portion of the detach/re-attach procedure the control unit110may report a UE capability equal to UE category 4 for Sub2197to the second communication network195. At block370, the control unit110may assign two RX chains (e.g., the second RX chain142and the third RX chain144) to Sub2197. Accordingly, with the mobile communication device100configured as UE category 4 for Sub2197, Sub2197may have two RX chains (e.g., the second RX chain142and the third RX chain144) available to decode a SIP_INVITE and enter traffic mode to receive a VoLTE call.

One of ordinary skill in the art will appreciate that processor executable instructions for executing the method300by the control unit110may be stored in the memory180operably connected to the control unit110.

In various examples, for a DSDA mobile communication device (e.g., the mobile communication device100) one subscription (e.g., Sub2197) may be selected as the DDS and the non-DDS subscription (e.g., Sub1192) may report a rank indicator (RI) equal to 1 for all traffic conditions without calculating any channel parameters. The non-DDS subscription may subsequently be assigned one RX chain or two RX chains.

FIG. 4is a flowchart of a method400for receiving Voice over Long Term Evolution (VoLTE) calls on a UE category 4 multi subscriber identity module multi-active (MSMA) mobile communication device according to various examples. Referring toFIGS. 1A, 1B, and 4, at block405, Sub1192may be a non-DDS and Sub2197may be a DDS subscription. For both Sub1192and Sub2197, the control unit110may initially report a UE category 4 for the mobile communication device100.

At block410, the control unit110may cause Sub1192to enter traffic mode. For LTE, the mobile communication device may periodically report a rank indictor (RI) to the network. The RI may equal one (i.e., one data stream received on one RX chain), or the RI may equal two (i.e., two data streams received on two RX chains). At block415the control unit110may report a rank indicator (RI) equal to 1 for Sub1192. For example, the control unit110may report an RI equal to 1 to the first communication network190for Sub1192for all traffic without calculating any channel parameters to determine channel conditions.

At block420, the control unit110may determine the channel conditions for Sub1192. For example, the control unit110may cause the communication unit (e.g., the first communication unit120) for Sub1192to measure one or more channel parameters, for example, but not limited to, the Reference Signal Received Power (RSRP), signal to noise ratio (SNR), etc. At block425, the control unit110may determine whether the one or more measured channel parameters (e.g., the RSRP, SNR, etc.) is greater than or equal to a threshold value. For example, the control unit110may determine whether the measured channel parameter is greater than or equal to a value in a range of −100 dBm to −80 dBm. In response to determining that the measured channel parameter is greater than or equal to the threshold value (425-Y), at block430the control unit110may assign one RX chain (e.g., the first RX chain140) to Sub1192.

In response to determining that the measured channel parameter s not greater than or equal to the threshold value (425-N), at block435the control unit110may assign two RX chains (e.g., the second RX chain142and the third RX chain144) to Sub1192. However, at block440Sub1192may still report an RI equal to 1. Thus, even though two RX chains may be assigned to Sub1192the control unit110may report an RI equal to 1 to the first communication network190for Sub1192. Assigning two RX chains to the non-DDS subscription Sub1192may improve the ability of the mobile communication device100to sustain a VoLTE call on the non-DDS subscription. At block445Sub1192may continue in traffic mode at block435.

At block450Sub2197may enter traffic mode. For example, a page may be received on Sub2197. Sub2197may set up a PS connection and receive a SIP_INVITE indicating a VoLTE call request. Sub2197may then enter traffic mode to receive the VoLTE call. At block455the control unit110may report an RI to the communication network (e.g., the second communication network195) according to the remaining number of RX chains. For example, if the control unit110assigns one RX chain to Sub1192, the control unit110may report an RI equal to 2 to the second communication network195for Sub2197. If the control unit110assigns two RX chains to Sub1192, the control unit110may report an RI equal to 1 to the second communication network195for Sub2197. Thus, the control unit110may give the VoLTE call a higher priority in assignment of the RX chains.

One of ordinary skill in the art will appreciate that processor executable instructions for executing the method400by the control unit110may be stored in the memory180operably connected to the control unit110.

The methods300and400, respectively, may be embodied on a non-transitory computer readable medium, for example, but not limited to, the memory180or other non-transitory computer readable medium known to those of skill in the art, having stored therein a program including computer executable instructions for making a processor, computer, or other programmable device execute the operations of the methods.

The various embodiments illustrated and described are provided merely as examples to illustrate various features of the claims. However, features shown and described with respect to any given embodiment are not necessarily limited to the associated embodiment and may be used or combined with other embodiments that are shown and described. Further, the claims are not intended to be limited by any one example embodiment.

The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the protection. For example, the example apparatuses, methods, and systems disclosed herein can be applied to multi-SIM wireless devices subscribing to multiple communication networks and/or communication technologies. The various components illustrated in the figures may be implemented as, for example, but not limited to, software and/or firmware on a processor, ASIC/FPGA/DSP, or dedicated hardware. Also, the features and attributes of the specific example embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure.

Although the present disclosure provides certain example embodiments and applications, other embodiments that are apparent to those of ordinary skill in the art, including embodiments which do not provide all of the features and advantages set forth herein, are also within the scope of this disclosure. Accordingly, the scope of the present disclosure is intended to be defined by reference to the appended claims.