Detection of fades for receive diversity enablement in a fading channel

The disclosure discloses enabling/disabling receive diversity, including determining the UE in a receive diversity enabled state; comparing a first and second receive chain filtered channel chip energy to interference density ratio to an EcI0 threshold, wherein the first and second receive chain filtered channel chip energy to interference density ratios are based on at least two power measurements obtained in the receive diversity enabled state; comparing a first receive chain measured number of Ec/I0 samples below EcI0_LCR_thrshld to a non-receive diversity threshold, wherein the first receive chain measured number of Ec/I0 samples is based on the first receive chain filtered channel chip energy to interference density ratio; and comparing a second receive chain measured number of Ec/I0 samples below EcI0_LCR_thrshld to the non-receive diversity threshold, wherein the second receive chain measured number of Ec/I0 samples is based on the second receive chain filtered channel chip energy to interference density ratio.

TECHNICAL FIELD

Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to operating a user equipment with at least two antennas to enable and disable receive diversity dynamically in a fading channel.

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 a cdma 2000 system. In another example, the network is a UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP).

Generally, wireless user equipment (e.g., referred to as mobile station (MS), mobile terminal (MT), access terminal (AT), etc. in various literature) configured for the network uses a SIM card to store subscriber identity and for other security and authentication purposes. SIM stands for subscriber identity module. More recently, some UEs have multiple SIM cards such that the user of the device can engage in calls or data communication on two or more different subscriptions. In general, each subscription is specified by a set of services and an identity associated with a network (e.g., cdma2000, UMTS). These subscriptions might be on the same network or different networks. A UE with multiple SIM cards is generally referred to as a multi-SIM device. Some such multi-SIM devices utilize a radio frequency (RF) resource (e.g., modem, transceiver), which is shared for accessing multiple subscriptions. However, there are certain limitations on carrying communications concurrently or simultaneously on multiple subscriptions while sharing the same RF resource.

As the demand for mobile broadband access continues to increase, research and development continue to advance multi-SIM wireless technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications. One such advance is the usage of receiver diversity with a single SIM or multiple SIM mobile device.

SUMMARY

According to various aspects of the disclosure, a method of wireless communication operable at a user equipment (UE) configured for enabling or disabling receive diversity, includes determining if the UE is in a receive diversity enabled (RxD) state at a current time interval; comparing a first receive chain filtered channel chip energy to interference density ratio to an EcI0threshold; comparing a second receive chain filtered channel chip energy to interference density ratio to the EcI0threshold, wherein the first and second receive chain filtered channel chip energy to interference density ratios are based on at least two power measurements obtained in the receive diversity enabled (RxD) state; comparing a first receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to a non-receive diversity threshold, LCR_thrshld_toNonRxD, wherein the first receive chain measured number of Ec/I0samples is based on the first receive chain filtered channel chip energy to interference density ratio; and comparing a second receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to the non-receive diversity threshold, LCR_thrshld_toNonRxD, wherein the second receive chain measured number of Ec/I0samples is based on the second receive chain filtered channel chip energy to interference density ratio. In some examples, the method further includes determining if either the first or the second, or both the first and the second receive chain filtered channel chip energy to interference density ratio is less than the EcI0threshold; or determining if either the first or the second, or both the first and the second receive chain measured number of Ec/I0samples is greater than or equal to the non-receive diversity threshold, LCR_thrshld_toNonRxD; and setting a receiver in the UE to a receive diversity enabled state in a next time interval, wherein the next time interval follows the current time interval. And, in some examples, the method further includes determining that the first and the second receive chain filtered channel chip energy to interference density ratio is greater than or equal to the EcI0threshold; determining that the first and the second receive chain measured number of Ec/I0samples is less than the non-receive diversity threshold, LCR_thrshld_toNonRxD; and setting a receiver in the UE to a receive diversity disabled state in a next time interval, wherein the next time interval follows the current time interval.

According to various aspects of the disclosure, a method of wireless communication operable at a user equipment (UE) configured for enabling or disabling receive diversity, includes determining if the UE is in a receive diversity enabled (RxD) state at a current time interval; comparing a receive chain filtered channel chip energy to interference density ratio to an EcI0threshold, wherein the receive chain filtered channel chip energy to interference density ratio is based on a power measurement obtained in the receive diversity enabled (RxD) state; and comparing a receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to a receive diversity threshold, LCR_thrshld_toRxD, wherein the receive chain measured number of Ec/I0samples is based on the receive chain filtered channel chip energy to interference density ratio. In various examples, the method further includes determining that the receive chain filtered channel chip energy to interference density ratio is less than the EcI0threshold; or determining that the receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld is greater than or equal to the receive diversity threshold, LCR_thrshld_toRxD; and setting a receiver in the UE to a receive diversity enabled state in a next time interval, wherein the next time interval follows the current time interval. In some examples, the method further includes determining if the receive chain filtered channel chip energy to interference density ratio is greater than or equal to the EcI0threshold; determining if the receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld is less than the receive diversity threshold, LCR_thrshld_toRxD and setting a receiver in the UE to a receive diversity disabled state in a next time interval, wherein the next time interval follows the current time interval.

According to various aspects of the disclosure, an apparatus for wireless communication operable at a user equipment (UE) configured for enabling or disabling receive diversity, includes means for determining if the UE is in a receive diversity enabled (RxD) state at a current time interval; means for comparing a first receive chain filtered channel chip energy to interference density ratio to an EcI0threshold; means for comparing a second receive chain filtered channel chip energy to interference density ratio to the EcI0threshold, wherein the first and second receive chain filtered channel chip energy to interference density ratios are based on at least two power measurements obtained in the receive diversity enabled (RxD) state; means for comparing a first receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to a non-receive diversity threshold, LCR_thrshld_toNonRxD, wherein the first receive chain measured number of Ec/I0samples is based on the first receive chain filtered channel chip energy to interference density ratio; and means for comparing a second receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to the non-receive diversity threshold, LCR_thrshld_toNonRxD, wherein the second receive chain measured number of Ec/I0samples is based on the second receive chain filtered channel chip energy to interference density ratio. In some examples, the apparatus further includes means for determining if either the first or the second, or both the first and the second receive chain filtered channel chip energy to interference density ratio is less than the EcI0threshold; or determining if either the first or the second, or both the first and the second receive chain measured number of Ec/I0samples is greater than or equal to the non-receive diversity threshold, LCR_thrshld_toNonRxD; and means for setting a receiver in the UE to a receive diversity enabled state in a next time interval, wherein the next time interval follows the current time interval. In some examples, the apparatus further includes means for determining that the first and the second receive chain filtered channel chip energy to interference density ratio is greater than or equal to the EcI0threshold; means for determining that the first and the second receive chain measured number of Ec/I0samples is less than the non-receive diversity threshold, LCR_thrshld_toNonRxD; and means for setting a receiver in the UE to a receive diversity disabled state in a next time interval, wherein the next time interval follows the current time interval.

According to various aspects of the disclosure, an apparatus for wireless communication operable at a user equipment (UE) configured for enabling or disabling receive diversity, includes means for determining if the UE is in a receive diversity enabled (RxD) state at a current time interval; means for comparing a receive chain filtered channel chip energy to interference density ratio to an EcI0threshold, wherein the receive chain filtered channel chip energy to interference density ratio is based on a power measurement obtained in the receive diversity enabled (RxD) state; and means for comparing a receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to a receive diversity threshold, LCR_thrshld_toRxD, wherein the receive chain measured number of Ec/I0samples is based on the receive chain filtered channel chip energy to interference density ratio. In some examples, the apparatus further includes means for determining that the receive chain filtered channel chip energy to interference density ratio is less than the EcI0threshold; or means for determining that the receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld is greater than or equal to the receive diversity threshold, LCR_thrshld_toRxD; and means for setting a receiver in the UE to a receive diversity enabled state in a next time interval, wherein the next time interval follows the current time interval. In some examples, the apparatus further includes means for determining if the receive chain filtered channel chip energy to interference density ratio is greater than or equal to the EcI0threshold; means for determining if the receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld is less than the receive diversity threshold, LCR_thrshld_toRxD and means for setting a receiver in the UE to a receive diversity disabled state in a next time interval, wherein the next time interval follows the current time interval.

According to various aspects of the disclosure, an apparatus for wireless communication operable at a user equipment (UE) configured for enabling or disabling receive diversity, includes a controller configured for determining if the UE is in a receive diversity enabled (RxD) state at a current time interval; and a channel decoder configured for comparing a first receive chain filtered channel chip energy to interference density ratio to an EcI0threshold, and for comparing a second receive chain filtered channel chip energy to interference density ratio to the EcI0threshold, wherein the first and second receive chain filtered channel chip energy to interference density ratios are based on at least two power measurements obtained in the receive diversity enabled (RxD) state; and wherein the controller is further configured for comparing a first receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to a non-receive diversity threshold, LCR_thrshld_toNonRxD, wherein the first receive chain measured number of Ec/I0samples is based on the first receive chain filtered channel chip energy to interference density ratio, and for comparing a second receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to the non-receive diversity threshold, LCR_thrshld_toNonRxD, wherein the second receive chain measured number of Ec/I0samples is based on the second receive chain filtered channel chip energy to interference density ratio. In some example, wherein if either the first or the second, or both the first and the second receive chain filtered channel chip energy to interference density ratio is less than the EcI0threshold; or if either the first or the second, or both the first and the second receive chain measured number of Ec/I0samples is greater than or equal to the non-receive diversity threshold, LCR_thrshld_toNonRxD, then the controller is further configured for setting a receiver in the UE to a receive diversity enabled state in a next time interval, wherein the next time interval follows the current time interval. In some examples, wherein if the first and the second receive chain filtered channel chip energy to interference density ratio is greater than or equal to the EcI0threshold and if the first and the second receive chain measured number of Ec/I0samples is less than the non-receive diversity threshold, LCR_thrshld_toNonRxD, then the controller is further configured for setting a receiver in the UE to a receive diversity disabled state in a next time interval, wherein the next time interval follows the current time interval.

According to various aspects of the disclosure, an apparatus for wireless communication operable at a user equipment (UE) configured for enabling or disabling receive diversity, includes a controller configured for determining if the UE is in a receive diversity enabled (RxD) state at a current time interval; and a channel decoder for comparing a receive chain filtered channel chip energy to interference density ratio to an EcI0threshold, wherein the receive chain filtered channel chip energy to interference density ratio is based on a power measurement obtained in the receive diversity enabled (RxD) state; and wherein the controller is further configured for comparing a receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to a receive diversity threshold, LCR_thrshld_toRxD, wherein the receive chain measured number of Ec/I0samples is based on the receive chain filtered channel chip energy to interference density ratio. In some examples, if the receive chain filtered channel chip energy to interference density ratio is less than the EcI0threshold, or if the receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld is greater than or equal to the receive diversity threshold, LCR_thrshld_toRxD, then the controller is further configured for setting a receiver in the UE to a receive diversity enabled state in a next time interval, wherein the next time interval follows the current time interval. In some examples, if the receive chain filtered channel chip energy to interference density ratio is greater than or equal to the EcI0threshold, and if the receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld is less than the receive diversity threshold, LCR_thrshld_toRxD, then the controller is further configured for setting a receiver in the UE to a receive diversity disabled state in a next time interval, wherein the next time interval follows the current time interval.

According to various aspects of the disclosure, a computer-readable storage medium storing computer executable code, operable on a device including at least one processor; a memory for storing a plurality of victim bands, the memory coupled to the at least one processor; and the computer executable code includes instructions for causing the at least one processor to determine if the UE is in a receive diversity enabled (RxD) state at a current time interval; instructions for causing the at least one processor to compare a first receive chain filtered channel chip energy to interference density ratio to an EcI0threshold; instructions for causing the at least one processor to compare a second receive chain filtered channel chip energy to interference density ratio to the EcI0threshold, wherein the first and second receive chain filtered channel chip energy to interference density ratios are based on at least two power measurements obtained in the receive diversity enabled (RxD) state; instructions for causing the at least one processor to compare a first receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to a non-receive diversity threshold, LCR_thrshld_toNonRxD, wherein the first receive chain measured number of Ec/I0samples is based on the first receive chain filtered channel chip energy to interference density ratio; and instructions for causing the at least one processor to compare a second receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to the non-receive diversity threshold, LCR_thrshld_toNonRxD, wherein the second receive chain measured number of Ec/I0samples is based on the second receive chain filtered channel chip energy to interference density ratio.

According to various aspects of the disclosure, a computer-readable storage medium storing computer executable code, operable on a device including at least one processor; a memory for storing a plurality of victim bands, the memory coupled to the at least one processor; and the computer executable code includes instructions for causing the at least one processor to determine if the UE is in a receive diversity enabled (RxD) state at a current time interval; instructions for causing the at least one processor to compare a receive chain filtered channel chip energy to interference density ratio to an EcI0threshold, wherein the receive chain filtered channel chip energy to interference density ratio is based on a power measurement obtained in the receive diversity enabled (RxD) state; and instructions for causing the at least one processor to compare a receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to a receive diversity threshold, LCR_thrshld_toRxD, wherein the receive chain measured number of Ec/I0samples is based on the receive chain filtered channel chip energy to interference density ratio.

DETAILED DESCRIPTION

Aspects of the present disclosure improve demodulation performance in single SIM or multi-SIM mobile devices in a fading channel. The description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

One or more aspects of the disclosure provide for a wireless user equipment (UE) configured to enable communication with two or more receive chains simultaneously using receive diversity, wherein each subscription may be in the same or in different radio access technologies (RAT). In various examples, the UE may include wireless devices, wireless receivers, mobile devices, mobile stations, mobile terminals, access terminals, etc. The UE may be a single SIM or a multi-SIM device that has one or multiple SIM applications stored on one or more SIM cards. In some aspects of the disclosure, however, the SIM applications may be stored at the UE without using any soft SIM models.

The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards.FIG. 1ais a conceptual diagram illustrating a first example of a telecommunications system according to some aspects of the present disclosure. Referring now toFIG. 1a, as an illustrative example without limitation, various aspects of the present disclosure are illustrated with reference to a Universal Mobile Telecommunications System (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. 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 (UE) in UMTS applications, but may also be referred to by those skilled in the art as a mobile station (MS), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. In a UMTS system, the UE110may further include a universal subscriber identity module (USIM)111(111A and111B), 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 such as cdma2000 and Long Term Evolution (LTE) 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 Home Location Register (HLR), Visitor Location Register (VLR), and Authentication Center (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 universal integrated circuit cards (UICCs), 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. 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. UEs such as the UE110having multiple USIMs are sometimes referred to as multi-SIM devices, with one particular example with two USIMs being called Dual SIM Dual Standby (DSDS) device or dual-SIM device. A DSDS device is generally capable of being active on two networks (or subscriptions) concurrently or simultaneously in standby mode, where an RF resource (e.g., transceiver) at 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 device.

As described above, the illustrated UE110is an example of a DSDS device capable of maintaining two subscriptions on the UMTS network100and or other networks. 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, in various aspects of the disclosure, 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, multi-SIM/multi-standby devices, or any device capable of monitoring channels on two or more subscriptions on any one or any plural number of RATs is generally referred to as a multi-standby device.

FIG. 1bis a conceptual diagram illustrating a second example of a telecommunications system in according to some aspects of the present disclosure. InFIG. 1b, various aspects of the present disclosure are illustrated for a wide area network (WAN) with reference to an Evolution Data Only (EVDO) system130as part of the 3GPP2 protocol family. The EVDO system130includes three interacting domains: a core network170, a RAN150and a mobile station (MS)140. The RAN150may include a plurality of Base Transceiver Systems (BTS)155, each controlled by a respective Base Station Controller (BSC)156. The RAN150may include any number of BTSs155and BSCs156in addition to the illustrated BTS155and BSC156. The BSC156may be responsible for radio resource management within the BTS155.

The geographic region covered by the BTS155may be divided into a number of cells, with a radio transceiver apparatus serving each cell, also known as a base station (BS). The BTS155may provide radio access to the core network170for any number of mobile stations (MS)140. The MS140is also referred to as user equipment (UE). For illustration, inFIG. 1b, one MS140is shown in communication with a BTS155over a Uu interface. The downlink (DL), also known as forward link, refers to the communication link from a BTS155to a MS140. The uplink (UL), also known as reverse link, refers to the communication link from a MS140to a BTS155.

The core network170may interface with one or more access networks, such as the RAN150. As shown, the core network170is an EVDO core network. However, the various concepts presented here may be implemented by any suitable access network to provide the MS140with access to other core networks. In a cdma2000 system, the MS140may further include one or more subscriber identity modules (not shown).

The core network170may include a circuit switched interface161and a packet switched interface162from the RAN150. Circuit switched services are handled by mobile switching center (MSC)171and packet switched services are handled by packet data serving node (PDSN)172. The MSC171may connect to a public switched telephony network (PSTN)181or any other circuit switched network. The PDSN172may connect to the Internet182or any other packet switched network. In addition, the core network170may provide an inter-working function (IWF)173to facilitate cross-domain connectivity between MSC171and the Internet182. Also, an authentication authorization and accounting (AAA) server174provides various security services in the core network170.

The RAN150air interface may be a spread spectrum Code Division Multiple Access (CDMA) system which may use a variety of wireless access standards such as the cdma2000 family. Although various examples described herein may refer to a CDMA air interface, the underlying principles are equally applicable to any suitable air interface.

FIG. 2is a conceptual diagram illustrating an example of an access network according to some aspects of 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, a first cell may utilize a first scrambling code, and a second cell, 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 network104,170(seeFIGS. 1aand 1b) for all the UEs230,232,234,236,238, and240in the respective cells202,204, and206.

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 some aspects of the disclosure, any of the UEs inFIG. 2may be a single SIM device, multi-SIM device or a DSDS device supporting multiple subscriptions.

In a wireless telecommunication system, the communication protocol architecture may take on various forms depending on the particular application. For example, in a UMTS system or a 3GPP2 cdma2000 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. 1a) or between MS140and core network170(referring toFIG. 1b), 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).

FIG. 3is a conceptual diagram illustrating an example of a radio protocol architecture 300 for the user and control plane according to some aspects of the present disclosure. 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 UE and Node B over the physical layer306.

At Layer 3, the radio resource control (RRC) layer316handles the control plane signaling between the UE and the Node B. RRC layer316includes a number of functional entities for routing higher layer messages, handling broadcasting and paging functions, establishing and configuring radio bearers, etc.

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.FIG. 3is applicable to both 3GPP and 3GPP2 wireless systems although some of the functional blocks, RRC316, PDCP314, RLC312, etc. may be designated by different names.

FIG. 4is a conceptual diagram illustrating a user equipment (UE)400configured for multi-SIM/multi-standby operation according to some aspects of the present disclosure. In an aspect of the disclosure, the UE400may be any of the UEs illustrated inFIGS. 1a, 1band/or2, which may be configured to communicate with two or more subscriptions (e.g., a primary subscription and a secondary subscription ofFIG. 6). The UE400has a subscription manager402, a channel decoder404, a signaling protocol stack406, a communication interface408, a first SIM (SIM1)410and a second SIM (SIM2)412. Alternatively, a single SIM may be used. These components ofFIG. 4may be implemented in software, hardware, firmware, or a combination thereof. The subscription manager402manages the subscriptions that the UE400may communicate with under various conditions. For example, the UE400may operate with a primary subscription and a secondary subscription in a DSDS operation. The channel decoder404may decode various channels from the primary subscription or secondary subscription. For example, the channel decoder404may decode a downlink Dedicated Physical Channel (DPCH) that carries signaling messages from the network. The signaling protocol stack406may be the same as the signaling protocol stack shown inFIG. 3and adapted to support communication with more than one subscriptions. Alternatively, UE400may have a single subscription and a single SIM.

The communication interface408provides a means for communicating with various other apparatus over a transmission medium. In an aspect of the disclosure, the UE400includes two SIMs410and412, associated with different subscriptions or networks. The UE400may use the communication interface408to access the different subscriptions associated with the SIMs410and412. In some aspects of the disclosure, the communication interface408may include a transceiver that is time-shared by the subscriptions. Alternatively, the communication interface408may include two transceivers that may individually access two subscriptions.

In various examples, the UE400may include a threshold manager409(not shown). The threshold manager409may be configured to perform threshold testing. In some aspects, the threshold manager409is embedded in one of the following components of the UE: the subscription manager402, the channel decoder404, the signaling protocol stack406or the communication interface408. In other aspects, the threshold manager409is a component within the UE400and separate from the other components of the UE.

FIG. 5is a block diagram illustrating an example of a hardware implementation for an apparatus500employing a processing system514according to some aspects of the present disclosure. In various examples, the apparatus500may be a user equipment. 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 system514that includes one or more processors504. For example, any of the UEs inFIGS. 1a, 1b,2or4may be implemented with the apparatus500. Examples of processors504include 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 configured to perform the various functionality described throughout the present disclosure. In various examples, the processor504may include a controller507(not shown). The controller507may be configured to set the receiver to diversity enabled mode or to diversity disabled mode. Although the controller507may be implemented within the processor504, it may also be implemented as an external component to the processor504.

In some aspects of the disclosure, blocks402to408ofFIG. 4may be implemented by the processor504and/or transceiver510ofFIG. 5. Also, SIMs410and412may be the same as the SIM511A and SIM511B ofFIG. 5. In some aspects of the disclosure, the radio protocol architecture ofFIG. 3or signaling protocol stack of406may be implemented by the processor504and/or memory505ofFIG. 5.

In this example, the processing system514may be implemented with a bus architecture, represented generally by the bus502. The bus502may include any number of interconnecting buses and bridges depending on the specific application of the processing system514and the overall design constraints. The bus502links together various circuits or components including one or more processors (represented generally by the processor504), a memory505, computer-readable media (represented generally by the computer-readable medium506), and one or more SIMs511A and511B The bus502may 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 interface508provides an interface between the bus502and a transceiver510. The transceiver510provides a means for communicating with various other apparatus over a transmission medium. The transceiver510may be used to access one or more subscriptions respectively associated with the SIMs511A and511B.

In some examples of a UE device such as the illustrated UE110or UE400including two SIMs, even though the SIMs may be utilized by different subscriptions or networks, the subscriptions may share a RF resource such as a single transceiver510. Alternatively, the subscriptions may have dedicated RF resources such as two transceivers510.

Depending upon the nature of the apparatus, a user interface512(e.g., keypad, display, speaker, microphone, joystick, a touchscreen, a touchpad) may also be provided. The processor504is responsible for managing the bus502and general processing, including the execution of software stored on the computer-readable medium506. The software when executed by the processor504, causes the processing system514to perform the various functionalities described in relation toFIGS. 6-9for any particular apparatus. The computer-readable medium506may also be used for storing data that is manipulated by the processor504when executing software.

In various aspects of the disclosure, a UE may simultaneously or concurrently perform two different communication activities, including but not limited to connecting with two different networks, or two different subscriptions within the same network, or two cells in a cellular network. Particularly, the UE may be enabled to continue to be engaged in ongoing communication activities on one subscription, while simultaneously or concurrently performing other communication activities on another subscription, such as receiving paging messages, traffic signal, performing SMS messaging, or receiving other information on a different subscription or from a different cell.

FIG. 6is a conceptual diagram600illustrating a user equipment (UE)602configured to operate in a primary subscription604and a secondary subscription606according to some aspects of the present disclosure. In an example, the UE602may be any of the UEs illustrated inFIGS. 1a, 1b,2, and4, which may be implemented by the apparatus500. In one aspect of the disclosure, the UE602may include a subscription manager402ofFIG. 4to manage multiple subscriptions. The UE602may also have two receive chains capable of achieving receive diversity with two propagation paths, a first path610and a second path608. Alternatively, the UE602may have a single subscription with a single SIM.

In a wireless communication system, communication performance is a function of many factors. One important factor is the link condition of the channel. The channel is the propagation path between the transmitter and receiver. The link condition is the propagation state of the channel. That is, the propagation state of the channel is the loss of the channel as well as the amplitude and phase distortion in the channel. In general, the link condition is time varying such that communication performance is also time varying.

In an ideal channel, there is no distortion in amplitude or phase introduced by the channel and the only loss is due to intrinsic free space loss (i.e., intrinsic free space loss is propagation loss due solely to the link geometry between the transmitter and receiver with no losses due to the propagation medium itself). In this case, the link condition is ideal since the receive power level will be at its maximum possible level. In an actual channel, amplitude and phase distortion in the channel may occur and there may be other losses in the channel beyond intrinsic free space loss. In this case, the link condition may be degraded. Thus, the receiver may be designed taking into account the link conditions of the actual channel to obtain the best communication performance.

One example of an actual channel is a fading channel. In the fading channel, the receive signal experiences a power reduction or fade over a time period. A fade degrades the communication performance, for example, the channel chip energy to noise density ratio Ec/N0, the channel chip energy to interference density ratio Ec/I0, the carrier to noise ratio C/N0, the bit error rate (BER), etc. For example, a fade may be divided into two types: slow fade and fast fade. A slow fade typically implies that a coherence time of the channel is much greater than an allowable delay spread in the receive signal. A fast fade typically implies that the coherence time of the channel is much less than the allowable delay spread in the receive signal. For example, the coherence time may be approximated by the time duration for which the propagation state of the channel is essentially constant. For example, the allowable delay spread of a signal is the allowable time extent of multiple copies of the same signal.

One mitigation strategy against a fading channel is receive diversity. For example, receive diversity refers to the capability of a mobile device or any wireless device to receive and process more than one receive signal which contain the same receive waveform. Receive diversity may improve communication performance in fading channel conditions.

In several examples, a mobile device (i.e., a user equipment) may allow receive diversity. The mobile device may include a plurality of receive chains, where each receive chain independently receives a receive signal. Each of the plurality of receive chains may include an antenna. In various examples, high order (i.e., greater than two antennas) receive diversity may be implemented.

Receive diversity is a receiver configuration that may be enabled or disabled, depending on link conditions of the channel. For example, receive diversity may be disabled when the link conditions result in good communication performance, i.e., the link is nominal. Alternatively, receive diversity may be enabled when link conditions result in poor communication performance, i.e., the link is degraded. Since receive diversity consumes more system resources, e.g., bandwidth, transmit power, etc., receive diversity may be enabled only when necessary.

In various aspects, a receiver may detect a fade and implement a fade mitigation strategy to maintain communication performance in the presence of a fade. The fade mitigation strategy may be to enable or disable receive diversity based on a threshold test. A threshold test may be a comparison of a power measurement against a threshold. For example, if the power measurement is equal to or above the threshold, then receive diversity may be disabled. For example, if the power measurement is less than the threshold, then receive diversity may be enabled.

In various examples, a receiver may compare a receive power measurement against a power threshold Tp, and decide whether or not to enable receive diversity. Alternately, the receiver may compare a channel chip energy to interference density ratio Ec/I0, against a first channel chip energy to interference density threshold T1and decide whether or not to enable receive diversity. Or, the receiver may compare a filtered channel chip energy to interference density ratio <Ec/I0>, against a second channel chip energy to interference density threshold T2and decide whether or not to enable receive diversity. For example, a filtered channel chip energy to interference density ratio may be computed by a simple average of a plurality of channel chip energy to interference density ratio values. Other parameters related to receive power may be used such as carrier-to-noise density ratio may be compared against a threshold.

However, in some propagation scenarios, the above threshold tests may not be robust and may result in degraded communication performance. For example, if the propagation scenario is a fast fade, the filtered channel chip enemy to interference density ratio may be above the second channel chip energy to interference density threshold T2and the receiver may disable receive diversity. However, in a fast fade, it may be desirable to enable receive diversity to maintain communication performance. In such propagation scenarios, a pseudo level crossing rate (PLCR) test may be employed as a fade detection and mitigation strategy to improve communication performance in the presence of a fast fade.

The PLCR test may employ a plurality of thresholds to decide whether to enable or disable receive diversity. For example, the receiver may make sequential power measurements of the receive signal in a sequential manner. That is, a Nthpower measurement may be obtained during time interval TNand a (N+1)thpower measurement may be obtained during time interval TN+1, where TN+1follows TN. A receive power measurement during time interval TNmay be used to enable or disable receive diversity during time interval TN+1. For example, each time interval may represent a wakeup interval, i.e., when the receiver is active (not idle). That is, a receive power measurement during a Nthwakeup interval may be used to enable or disable receive diversity during a (N+1)thwakeup interval.

In various examples, the PLCR test may combine a pseudo level crossing rate (PLCR) algorithm and an existing filtered channel chip energy to interference density ratio algorithm to yield improved detection of fades in either a fast or slow fading channel. As a result, the PLCR test may result in improved receive signal demodulation performance by proper selection of enabling and disabling of receive diversity. For example, the receive signal may be a paging signal or a traffic signal.

In various examples, the PLCR algorithm may calculate the rate where the receive power level or filtered channel chip energy to interference density ratio <Ec/I0>, is below a predefined level within a time interval or window. The rate may provide an upper bound of a true level cross rate. The rate may work well under both fast fading and slow fading conditions to identify channel quality or link condition.

In various examples, the PLCR test may use several thresholds to switch between a receive diversity enabled state and a receive diversity disabled state. A first threshold, denoted as “EcI0_LCR_thrshld”, may be applied to a power measurement during a current time interval TNto determine whether to enable or disable receive diversity for a next time interval TN+1. A second threshold, denoted as “LCR_thrshld_toRxD”, may be defined as M/S, where M is defined as a number of Ec/I0samples below EcI0_LCR_thrshld out of S Ec/I0samples. S is the total number of Ec/I0samples in the current time interval TN. A third threshold, denoted as “LCR_thrshld_toNonRxD”, may be defined as N/S, where N is defined as a number of Ec/I0samples above EcI0_LCR_thrshld out of S Ec/I0samples.

In various examples, if there are K Ec/I0samples out of S Ec/I0samples which are below EcI0_LCR_thrshld during a current time interval TN, then if K is greater than or equal to M, enable receive diversity in a next time interval TN+1. In various examples, if there are L Ec/I0samples out of S Ec/I0samples which are above EcI0_LCR_thrshld during a current time interval TN, then if L is less than N, disable receive diversity in a next time interval TN+1.

If the receiver is in a receive diversity enabled state, the filtered channel chip energy to interference density ratio may be calculated for each receive chain and the number of Ec/I0samples below EcI0_LCR_thrshld may be computed for each receive chain. For example, the receiver may have a first receive chain and a second receive chain. Given the power measurements from each receive chain, the receiver may determine: (1) whether to switch to receive diversity disabled state and (2) which receive chain to disable. For example, if both receive chains satisfy the filtered channel chip energy to interference density ratio threshold condition and the measured Ec/I0samples are less than LCR_thrshld_toNonRxD, then disable receive diversity in a next time interval TN+1. In addition, the first receive chain may be selected to be disabled.

In various aspects, the PLCR test may be summarized as follows:In a current time interval, start in receive diversity disabled state. If either of the following conditions are satisfied:filtered channel chip energy to interference density ratio <EcI0threshold, ormeasured number of Ec/I0samples below EcI0_LCR_thrshld≧LCR_thrshld_toRxD (i.e., out of S consecutive input samples, the measured number of Ec/Io samples counted to be below EcI0_LCR_thrshld is more than or equal to M),then enable receive diversity in a next time interval.In a current time interval, start in receive diversity enabled state. If both of the following conditions are satisfied:filtered channel chip energy to interference density ratio≧EcI0threshold, and,measured number of Ec/I0samples below EcI0_LCR_thrshld<LCR_thrshld_toNonRxD, (i.e., out of S consecutive input samples, the measured number of Ec/I0samples counted to be below EcI0_LCR_thrshld is less than N),then disable receive diversity in a next time interval.

FIG. 7is a diagram illustrating an example of a pseudo level crossing rate (PLCR) test algorithm700according to some aspects of the present disclosure. In block710, start the algorithm. In block720, determine if a UE is in a receive diversity enabled (RxD) state at a current time interval (i.e., current wakeup). If yes, proceed to block730. If no, proceed to block740. If no, only one receive chain is active.

In block730, compare a first receive chain filtered channel chip energy to interference density ratio (Ec/I0) to an interference density ratio threshold (EcI0threshold), and compare a second receive chain filtered channel chip energy to interference density ratio (Ec/I0) to the EcI0threshold, wherein the first and second receive chain filtered channel chip energy to interference density ratios are based on at least two power measurements obtained in the receive diversity enabled (RxD) state. If both comparisons are greater than or equal to the EcI0threshold (i.e., Rx chains satisfy filtered Ec/I0>=EcI0threshold), proceed to block750. If one comparison or both comparisons are less than the EcI0threshold (i.e., at least one Rx chain does NOT satisfy filtered Ec/I0>=EcI0threshold), proceed to block790. Hence, if either the first or the second, or both the first and the second receive chain filtered channel chip energy to interference density ratio is less than the EcI0threshold, proceed to block790. The comparison in block730applies for a diversity case where two Rx chains are active.

In block750, compare a first receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to a non-receive diversity threshold, LCR_thrshld_toNonRxD, and compare a second receive chain measured number of Ec/I0samples to the non-receive diversity threshold, LCR_thrshld_toNonRxD. In various examples, the first receive chain measured number of Ec/I0samples is based on the first receive chain filtered channel chip energy to interference density ratio. In various examples, the second receive chain measured number of Ec/I0samples is based on the second receive chain filtered channel chip energy to interference density ratio.

If both comparisons are less than the non-receive diversity threshold, LCR_thrshld_toNonRxD (i.e., Rx chains satisfy counted Ec/I0samples<LCR_thrshld_toNonRxD) proceed to block770. In block770, set the receiver to a receive diversity disabled state in a next time interval, wherein the next time interval follows the current time interval. If one comparison or both comparisons are greater than or equal to the non-receive diversity threshold, LCR_thrshld_toNonRxD (i.e., at least one Rx chain does not satisfy counted Ec/I0samples <LCR_thrshld_toNonRxD), proceed to block790. Hence, if either the first or the second, or both the first and the second receive chain measured number of Ec/I0samples is greater than or equal to the non-receive diversity threshold, LCR_thrshld_toNonRxD, proceed to block790.

In block740, compare the receive chain filtered channel chip energy to interference density ratio (Ec/I0) to the EcI0threshold. If the receive chain filtered channel chip energy to interference density ratio (Ec/I0) is less than the EcI0threshold (i.e., filtered Ec/I0<EcI0threshold), then proceed to block790. If the receive chain filtered channel chip energy to interference density ratio (Ec/I0) is greater than or equal to the EcI0threshold (i.e., filtered Ec/I0>=EcI0threshold), proceed to block760. The comparison in block740applies for a non-diversity case where only one Rx chain is active.

In block760, compare the receive chain measured number of Ec/I0samples to a receive diversity threshold LCR_thrshld_toRxD. If the measured number of Ec/I0samples below EcI0_LCR_thrshld is greater than or equal to the receive diversity threshold LCR_thrshld_toRxD (i.e., counted Ec/I0samples >=LCR_thrshld_toRxD), proceed to block790. If the receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld is less than the receive diversity threshold LCR_thrshld_toRxD (i.e., counted Ec/I0samples<LCR_thrshld_toRxD), proceed to block780.

In block780, set the receiver to a receive diversity disabled state in a next time interval, wherein the next time interval follows the current time interval. In various examples, the receiver is within the UE. In block790, set the receiver to a receive diversity enabled state in a next time interval, wherein the next time interval follows the current time interval. In various examples, when the receiver is set to the receive diversity enabled state, trigger hybrid fallback.

FIG. 8is a flow diagram illustrating a first example for enabling or disabling receive diversity. In block810, determine if the UE is in a receive diversity enabled (RxD) state at a current time interval. In various examples, the determination may be performed by the controller507(as illustrated inFIG. 5).

In block820, compare a first receive chain filtered channel chip energy to interference density ratio to an EcI0threshold. In various examples, the comparison may be performed by the channel decoder404(as illustrated inFIG. 4).

In block830, compare a second receive chain filtered channel chip energy to interference density ratio to the EcI0threshold, wherein the first and second receive chain filtered channel chip energy to interference density ratios are based on at least two power measurements obtained in the receive diversity enabled (RxD) state. In various examples, the comparison may be performed by the channel decoder404(as illustrated inFIG. 4).

In block840, compare a first receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to a non-receive diversity threshold, LCR_thrshld_toNonRxD, wherein the first receive chain measured number of Ec/I0samples is based on the first receive chain filtered channel chip energy to interference density ratio. In various examples, the comparison may be performed by the controller507(as illustrated inFIG. 5).

In block850, compare a second receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to the non-receive diversity threshold, LCR_thrshld_toNonRxD, wherein the second receive chain measured number of Ec/I0samples is based on the second receive chain filtered channel chip energy to interference density ratio. In various examples, the comparison may be performed by the controller507(as illustrated inFIG. 5).

In various aspects, if either the first or the second, or both the first and the second receive chain filtered channel chip energy to interference density ratio is less than the EcI0threshold; or if either the first or the second, or both the first and the second receive chain measured number of Ec/I0samples is greater than or equal to the non-receive diversity threshold, LCR_thrshld_toNonRxD, then set a receiver in the UE to a receive diversity enabled state in a next time interval, wherein the next time interval follows the current time interval. In various examples, the comparison may be performed by the controller507(as illustrated inFIG. 5).

In various aspects, if the first and the second receive chain filtered channel chip energy to interference density ratio is greater than or equal to the EcI0threshold, and if the first and the second receive chain measured number of Ec/I0samples is less than the non-receive diversity threshold, LCR_thrshld_toNonRxD, then set a receiver in the UE to a receive diversity disabled state in a next time interval, wherein the next time interval follows the current time interval. In various examples, the comparison may be performed by the controller507(as illustrated inFIG. 5).

FIG. 9is a flow diagram illustrating a second example for enabling or disabling receive diversity. In block910, determine if the UE is in a receive diversity enabled (RxD) state at a current time interval. In various examples, the determination may be performed by the controller507(as illustrated inFIG. 5).

In block920, compare a receive chain filtered channel chip energy to interference density ratio to an EcI0threshold, wherein the receive chain filtered channel chip energy to interference density ratio is based on a power measurement obtained in the receive diversity enabled (RxD) state. In various examples, the comparison may be performed by the channel decoder404(as illustrated inFIG. 4).

In block930, compare a receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld to a receive diversity threshold, LCR_thrshld_toRxD, wherein the receive chain measured number of Ec/I0samples is based on the receive chain filtered channel chip energy to interference density ratio. In various examples, the comparison may be performed by the controller507(as illustrated inFIG. 5).

In various aspects, if the receive chain filtered channel chip energy to interference density ratio is less than the EcI0threshold, or if the receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld is greater than or equal to the receive diversity threshold, LCR_thrshld_toRxD, then set a receiver in the UE to a receive diversity enabled state in a next time interval, wherein the next time interval follows the current time interval. In various examples, the setting may be performed by the controller507(as illustrated inFIG. 5).

In various aspects, if the receive chain filtered channel chip energy to interference density ratio is greater than or equal to the EcI0threshold, and if the receive chain measured number of Ec/I0samples below EcI0_LCR_thrshld is less than the receive diversity threshold, LCR_thrshld_toRxD, then set a receiver in the UE to a receive diversity disabled state in a next time interval, wherein the next time interval follows the current time interval. In various examples, the comparison may be performed by the controller507(as illustrated inFIG. 5).

In various examples, the pseudo level crossing rate (PLCR) test may well track fades in a fast fading channel. As a result, the PLCR test may enhance demodulation performance for a receive signal, e.g., a paging signal, by enabling receive diversity when the link is degraded. In addition, the PLCR test may avoid enabling receive diversity when the link is nominal.

Table 1 shows that the PLCR test may improve cdma2000 1× paging signal demodulation success rate by 5% to 20% under different link conditions. For example, in multimode L+1× (i.e., LTE plus cdma2000 1×) DR-DSDS scenario, the majority of enabling receive diversity operations may be triggered by the PLCR test.

FIG. 10illustrates an example of a 1× mobile device paging demodulation performance1000with and without a pseudo level crossing rate (PLCR) test. InFIG. 10, performance metrics for three different interference operating points is shown.

FIG. 11illustrates an example of a 1× mobile device paging demodulation performance1100with a pseudo level crossing rate (PLCR) test. InFIG. 11, performance gains for three different interference operating points is shown.

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.

By way of example, various aspects may be extended to systems employing UMTS (FDD, TDD), WCDMA, TD-SCDMA, GSM, Long Term Evolution (LTE) (in FDD, TDD, or both modes), LTE-Advanced (LTE-A) (in FDD, TDD, or both modes), CDMA2000, Evolution-Data Optimized (EV-DO), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra-Wideband (UWB), Bluetooth, and/or other suitable systems. The actual telecommunication standard, network architecture, and/or communication standard employed will depend on the specific application and the overall design constraints imposed on the system.