Patent Publication Number: US-2016226539-A1

Title: Receiver control based on error detection in multiple, simultaneous radio access technology environments

Description:
BACKGROUND 
     1. Field 
     Embodiments described herein generally relate to systems and methods for improved receiver control based on error detection results in multiple, simultaneous radio access technology environments. 
     2. Background 
     A user equipment (“UE”), such as a mobile phone device, may be enabled for one or more radio access technologies (“RATs”), such as Frequency Division Multiple Access (“FDMA”), Time Division Multiple Access (“TDMA”), Code Division Multiple Access (“CDMA”), Universal Mobile Telecommunications Systems (“UMTS”) (particularly, Long Term Evolution (“LTE”)), Global System for Mobile Communications (“GSM”), Wi-Fi, PCS, or other protocols that may be used in a wireless communications network or a data communications network. One or more RATs may be enabled by one, or a plurality of subscriber identity modules (“SIMs”). For example, a UE may be a multi-SIM UE, where each of a plurality of SIMs received or otherwise coupled to the multi-SIM UE may support one or more RATs. 
     SUMMARY 
     Various embodiments relate to systems and methods for improved receiver control based on error detection results in multiple, simultaneous radio access technology environments. 
     According to some embodiments, a method includes communicating using a first radio access technology on a first receiver. The method further includes receiving a first communication for a second radio access technology on a second receiver. The method further includes determining whether to receive a second communication for the second radio access technology on the first receiver based on an error detection result for the first communication. 
     In some embodiments, determining whether to receive the second communication for the second radio access technology on the first receiver results in a determination to use the first receiver for reception of the second communication for the second radio access technology if the error detection result for the first communication indicates an error for the first communication. 
     In some embodiments, determining whether to receive the second communication for the second radio access technology on the first receiver results in a determination to not use the first receiver for reception of the second communication for the second radio access technology if the error detection result for the first communication does not indicate an error for the first communication. 
     In some embodiments, the method further includes receiving the second communication for the second radio access technology on the first receiver if the error detection result for the first communication indicates an error for the first communication. 
     In some embodiments, the method further includes receiving the second communication for the second radio access technology on the second receiver if the error detection result for the first communication does not indicate an error for the first communication. 
     In some embodiments, the first communication comprises one or more bits. In such embodiments, the error detection result for the first communication indicates whether or not the one or more bits were received in error. 
     In some embodiments, the first communication comprises one or more bits. In such embodiments, the error detection result for the first communication indicates whether or not all information bits included in the first communication could be successfully recovered. 
     In some embodiments, the first communication comprises one or more bits. In such embodiments, the error detection result for the first communication indicates whether or not the one or more bits were detected as being in error after a decoding operation was performed for the first communication. 
     In some embodiments, the error detection result for the first communication indicates whether or not one or more bits of the first communication were detected as being in error after an error correction operation was performed for the first communication. 
     In some embodiments, the error detection result for the first communication indicates whether or not a block error was detected in the first communication. 
     In some embodiments, the error detection result for the first communication is a result of applying a cyclic redundancy check algorithm to a block of data received as part of the first communication. 
     In some embodiments, determining whether to receive the second communication for the second radio access technology on the first receiver is not performed based on a signal strength indicator. 
     In some embodiments, determining whether to receive the second communication for the second radio access technology on the first receiver is not performed based on a signal strength indicator for the second radio access technology during reception of the first communication for the second radio access technology on the second receiver. 
     In some embodiments, the method further includes stopping communication using the first radio access technology on the first receiver. In such embodiments, the method further includes receiving the second communication for the second radio access technology on the first receiver, after stopping the communication using the first radio access technology on the first receiver. In such embodiments, the method further includes resuming the communication or starting a new communication using the first radio access technology on the first receiver, after receiving the second communication for the second radio access technology on the first receiver. 
     In some embodiments, the method further includes stopping a communication using the first radio access technology on the second receiver, before receiving the first communication for the second radio access technology on the second receiver. In such embodiments, the method further includes receiving the first communication for the second radio access technology on the second receiver, after stopping the communication using the first radio access technology on the second receiver. In such embodiments, the method further includes resuming the communication or starting a new communication using the first radio access technology on the second receiver, after receiving the first communication for the second radio access technology on the second receiver. In such embodiments, communicating using a first radio access technology on a first receiver comprises communicating using the first radio access technology on the second receiver, before receiving the first communication for the second radio access technology on the second receiver. 
     In some embodiments, the method further includes determining to receive the second communication for the second radio access technology on the first receiver based on the error detection result for the first communication indicating that an error was detected for the first communication. In such embodiments, the method further includes stopping the communication using the first radio access technology on the first receiver, before receiving the second communication for the second radio access technology on the first receiver. In such embodiments, the method further includes receiving the second communication for the second radio access technology on the first receiver, after stopping the communication using the first radio access technology on the first receiver. In such embodiments, the method further includes resuming the communication or starting a new communication using the first radio access technology on the first receiver, after receiving the second communication for the second radio access technology on the first receiver. 
     In some embodiments, the method further includes stopping the communication using the first radio access technology on the second receiver, before receiving the second communication for the second radio access technology on the second receiver. In such embodiments, the method further includes receiving the second communication for the second radio access technology on the second receiver, after stopping the communication using the first radio access technology on the second receiver. In such embodiments, the method further includes resuming the communication or starting a new communication using the first radio access technology on the second receiver, after receiving the second communication for the second radio access technology on the second receiver. 
     In some embodiments, the method further includes determining to receive the second communication for the second radio access technology on the second receiver based on the error detection result for the first communication indicating that no error was detected for the first communication. In such embodiments, the method further includes stopping communication using the first radio access technology on the second receiver, before receiving the second communication for the second radio access technology on the second receiver. In such embodiments, the method further includes receiving the second communication for the second radio access technology on the second receiver, after stopping communication using the first radio access technology on the second receiver. In such embodiments, the method further includes resuming the communication or starting a new communication using the first radio access technology on the second receiver, after receiving the second communication for the second radio access technology on the second receiver. 
     In some embodiments, the first communication for the second radio access technology is received on the second receiver based on a tune-away operation on the second receiver from the first radio access technology to the second radio access technology. 
     In some embodiments, determining whether to receive a second communication for the second radio access technology on the first receiver comprises determining whether to perform a tune-away operation on the first receiver in order to receive the second communication. 
     In some embodiments, the first communication for the second radio access technology is a paging message for the second radio access technology. In such embodiments, the second communication for the second radio access technology is a paging message for the second radio access technology. 
     In some embodiments, the second communication for the second radio access technology is a next paging message for the second radio access technology expected to be received one paging interval in time after the first communication. 
     In some embodiments, communicating using the first radio access technology comprises performing active mode communications with a data network radio access technology. In such embodiments, the first communication for the second radio access technology comprises an idle mode communication with a voice network radio access technology. In such embodiments, the second communication for the second radio access technology comprises an idle mode communication with the voice network radio access technology. 
     In some embodiments, the first receiver is a receiver with a greater sensitivity than the second receiver. 
     In some embodiments, the second receiver provides spatial diversity reception for signals received at the first receiver. 
     In some embodiments, the first radio access technology is different from the second radio access technology. 
     According to some embodiments, a user equipment (UE) apparatus includes a first receiver configured to communicate using a first radio access technology, and a second receiver configured to receive a first communication for a second radio access technology. The UE apparatus further includes a processor configured to determine whether to receive a second communication for the second radio access technology on the first receiver based on an error detection result for the first communication. 
     According to some embodiments, a user equipment (UE) apparatus includes means for communicating using a first radio access technology on a first receiver. The UE apparatus further includes means for receiving a first communication for a second radio access technology on a second receiver. The UE apparatus further includes means for determining whether to receive a second communication for the second radio access technology on the first receiver based on an error detection result for the first communication. 
     According to some embodiments, a non-transitory computer-readable medium includes instructions configured to cause one or more computing devices to communicate using a first radio access technology on a first receiver. The medium includes instructions configured to cause one or more computing devices to receive a first communication for a second radio access technology on a second receiver. The medium includes instructions configured to cause one or more computing devices to determine whether to receive a second communication for the second radio access technology on the first receiver based on an error detection result for the first communication. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate exemplary embodiments, and together with the general description given above and the detailed description given below, serve to explain the features of the various embodiments. 
         FIG. 1  is a schematic diagram illustrating an example of a system according to various embodiments. 
         FIG. 2  is a functional block diagram illustrating an example of a user equipment according to various embodiments. 
         FIG. 3  is a schematic diagram illustrating an example of a user equipment according to various embodiments. 
         FIG. 4  is a schematic diagram illustrating a communication sequence according to various embodiments. 
         FIG. 5  is a schematic diagram illustrating a communication sequence according to various embodiments. 
         FIG. 6  is a flowchart of a process according to various embodiments. 
         FIG. 7  is a flowchart of a process according to various embodiments. 
         FIG. 8  is a flowchart of a process according to various embodiments. 
         FIG. 9  is a flowchart of a process according to various embodiments. 
         FIG. 10  is a component block diagram of a user equipment suitable for use with various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers may be used throughout the drawings to refer to the same or like parts. Different reference numbers may be used to refer to different, same, or similar parts. References made to particular examples and implementations are for illustrative purposes, and are not intended to limit the scope of the disclosure or the claim. 
     Various modern communication devices are described herein. Such a modern communication device may be referred to herein as a user equipment (“UE”). However, such a modern communication device may also be referred to as a mobile station (“MS”), a wireless device, a communications device, a wireless communications device, a mobile device, a mobile phone, a mobile telephone, a cellular device, a cellular telephone, and in other ways. Examples of UE include, but are not limited to, mobile phones, laptop computers, smart phones, and other mobile communication devices of the like that are configured to connect to one or more RATs. 
     Some UE may contain one or more subscriber identity modules (“SIMs”) that provide users of the UEs with access to one or multiple separate mobile networks, supported by radio access technologies (“RATs”). Examples of RATs may include, but are not limited to, Global Standard for Mobile (“GSM”), Code Division Multiple Access (“CDMA”), CDMA2000, Time Division-Code Division Multiple Access (“TD-CDMA”), Time Division-Synchronous Code Division Multiple Access (“TD-SCDMA”), Wideband-Code Division Multiple Access (“W-CDMA”), Time Division Multiple Access (“TDMA”), Frequency Division Multiple Access (“FDMA”), Long-Term Evolution (“LTE”), wireless fidelity (“Wi-Fi”), various 3G standards, various 4G standards, and the like. 
     Embodiments described herein relate to both single-SIM and multi-SIM UEs. A UE that includes a plurality of SIMs and connects to two or more separate RATs using a same set of RF resources (e.g., radio-frequency (“RF”) transceivers) is a multi-SIM-multi-standby (“MSMS”) communication device. In one example, the MSMS communication device may be a dual-SIM-dual-standby (“DSDS”) communication device, which may include two SIM cards/subscriptions that may both be active on standby, but one is deactivated when the other one is in use. In another example, the MSMS communication device may be a triple-SIM-triple-standby (“TSTS”) communication device, which includes three SIM cards/subscriptions that may all be active on standby, where two may be deactivated when the third one is in use. In other examples, the MSMS communication device may be other suitable multi-SIM communication devices, with, for example, four or more SIMs, such that when one is in use, the others may be deactivated. 
     Further, a UE that includes a plurality of SIMs and connects to two or more separate mobile networks using two or more separate sets of RF resources is termed a multi-SIM-multi-active (“MSMA”) communication device. An example MSMA communication device is a dual-SIM-dual-active (“DSDA”) communication device, which includes two SIM cards/subscriptions, each associated with a separate RAT, where both SIMs may remain active at any given time. In another example, the MSMA device may be a triple-SIM-triple-active (“TSTA”) communication device, which includes three SIM cards/subscriptions, each associated with a separate RAT, where all three SIMs may remain active at any given time. In other examples, the MSMA communication device may be other suitable multi-SIM communication devices, with, for example, four or more SIMs, such that all SIMs are active at any given time. 
     In addition, a plurality of modes may be enabled by one SIM such that each mode may correspond to a separate RAT. Such a SIM is a multi-mode SIM. A UE may include one or more multi-mode SIMs. The UE may be a MSMS communication device (such as, but not limited to, a DSDS or a TSTS communication device), a MSMA communication device (e.g., a DSDA, TSTA communication device, or the like), or a multi-mode device. 
     As used herein, UE refers to one of a cellular telephone, smart phone, personal or mobile multi-media player, personal data assistant, laptop computer, personal computers, tablet computer, smart book, palm-top computer, wireless electronic mail receiver, multimedia Internet-enabled cellular telephone, wireless gaming controller, and similar personal electronic device that include one or more SIMs, a programmable processor, memory, and circuitry for connecting to one or more mobile communication networks (simultaneously or sequentially). Various embodiments may be useful in mobile communication devices, such as smart phones, and such devices are referred to in the descriptions of various embodiments. However, the embodiments may be useful in any electronic device, such as a DSDS, a TSTS, a DSDA, a TSTA communication device (or other suitable multi-SIM, multi-mode devices), that may individually maintain one or more subscriptions that utilize one or a plurality of separate set of RF resources. 
     As used herein, the terms “SIM,” “SIM card,” and “subscriber identification module” are used interchangeably to refer to a memory that may be an integrated circuit or embedded into a removable card, and that stores an International Mobile Subscriber Identity (IMSI), related key, and/or other information used to identify and/or authenticate a wireless device on a network and enable a communication service with the network. Because the information stored in a SIM enables the UE to establish a communication link for a particular communication service with a particular network, the term “SIM” may also be used herein as a shorthand reference to the communication service associated with and enabled by the information (e.g., in the form of various parameters) stored in a particular SIM as the SIM and the communication network, as well as the services and subscriptions supported by that network, correlate to one another. 
     Embodiments described herein are directed to systems and methods for improved receiver control based on error detection results in multiple, simultaneous radio access technology environments. In environments where a UE supports multiple, simultaneous RATs, the UE may be required to employ various techniques for managing shared RF resources across those multiple RATs. For example, the UE may be required to allow both a first RAT and a second RAT to have periodic access to a primary RF chain, even though the radio access network (“RAN”) components (e.g., base stations, eNodeBs, etc.) for each of the first RAT and the second RAT do not coordinate their transmissions. As such, the UE may be required to selectively provide RF resources for communication on each of the first RAT and the second RAT despite conflicting demands for those RF resources. 
     In some configurations, the UE may contain a first receiver and a second receiver. The UE may be configured to use both of the first receiver and the second receiver to communicate using the first RAT. However, the UE may provide the second receiver for communication using the second RAT as needed. This approach may allow reception of communications for the second RAT while introducing slight errors in reception of communications for the first RAT (due to loss of the second receiver). This approach may be used when an active mode data communication requiring near constant receiver access is taking place on the first RAT, while less intensive idle mode communication is taking place on the second RAT. As an example, the UE may perform connected state communication with an LTE RAT on both the first receiver and second receiver, and the UE may periodically provide the second receiver for reception of a paging message on a CDMA2000 RAT. However, even with this approach, errors may occur for the second RAT communication while using the second receiver. This may be the case due to a poorer sensitivity for the second receiver as compared to the first receiver, or for other reasons. In some situations, a signal strength indicator (e.g., Ec/Io) for the second RAT may be used to determine if the second receiver is insufficient to receive the communication for the second RAT. If the signal strength indicator does not meet some predefined threshold, then the UE may provide the first receiver for the second RAT communication. This approach may improve reception of communications for the second RAT, but this approach may introduce significant errors in reception of communications for the first RAT (due to loss of the first receiver). As such, the determination to provide the first receiver for reception of communications on the second RAT should only be made as absolutely necessary. 
     However, a signal strength indicator may not be highly predictive of whether provision of the first receiver for reception of communications on the second RAT is absolutely necessary. Signal strength indicators may be deemed a logical metric for driving the determination for receiver allocation to the first RAT and the second RAT, at least because a weak signal in the downlink is expected to cause poor reception of the second RAT communication and a strong signal in the downlink is expected to cause good reception of the second RAT communication. Nonetheless, this general relationship between signal strength indicators and signal reception may suffer for two reasons. First, other factors may improve or degrade the reception of the second RAT communication apart from signal strength indicators. For example, the magnitude of desense occurring at the second receiver may vary with time and effectively change the sensitivity of the second receiver apart from the observed or measured signal strength indicators. As such, the signal strength indicators may not predict with great accuracy the quality with which the second RAT communication will be received at the second receiver. Second, the signal strength indicators may be overly biased in favor of providing the first receiver to the second RAT (i.e., overly pessimistic indicators of signal reception on the second receiver). For example, a signal strength indicator of Echo below some predefined threshold may cause the first receiver to be provided for the second RAT communication, whereas the second RAT communication could have been successfully received and decoded using only the second receiver. This may be the case based on mere chance of correct reception, gains from multipath, encoding techniques (e.g., forward error correction), or other reasons. As such, the signal strength indicators may cause provision of the first receiver to the second RAT even in cases where it would not be necessary. For at least these two reasons, signal strength indicators may not be ideal for use as the basis for determination of receiver or other RF resource allocation. 
     Accordingly, various embodiments described herein are directed to systems and methods for more effectively determining the provision of shared RF resources to multiple RATs. In some embodiments, a UE may use the second receiver for reception of a first communication for the second RAT. The UE may determine an error detection result for that first communication so as to determine if the first communication was received in error. If the first communication was not received in error, then the UE may again provide the second receiver for the next communication for the second RAT, at least because the second receiver was effective to receive the first communication. However, if the first communication was received in error, then the UE may provide the first receiver for the next communication for the second RAT. As an example, the UE may provide the first receiver and the second receiver for communication with an LTE RAT. The UE may provide the second receiver for reception of a first paging message for a CDMA2000 RAT. If a cyclic redundancy check (“CRC”) result for the first paging message indicates that the paging message was received and decoded without any block errors, then the UE may again provide the second receiver for reception of the next paging message for the CDMA2000 RAT. However, if the CRC result for the first paging message indicates that the paging message was not successfully decoded (i.e., the CRC result indicates block errors), then the UE may provide the first receiver for reception of the next paging message for the CDMA2000 RAT. 
     Determinations based on error detection results may be more effective than the aforementioned techniques based on signal strength indictors at least based on the greater accuracy of the error detection results. In particular, the error detection result may accurately report whether the second RAT communication was actually received in error. While the signal strength indicators provide a sort of prediction of success of the second RAT communication, the error detection result provides an actual indication of whether the information bits contained in the second RAT communication were successfully recovered. As such, while the signal strength indicators may not appropriately predict numerous factors including desense variations, inherent randomness in downlink channel noise effects, and enhanced recovery techniques in the receiver circuitry, the error detection result can incorporate these factors as the error detection result is determined after all of these factors have been applied. Therefore, the use of an error detection result may improve over techniques using signal strength indicators because the inherent degradation of signal reception for the first RAT caused by providing the first receiver to the second RAT will only be caused when recovery of information bits for communications on the second RAT actually fail with use of the second receiver. 
     Determinations based on error detection results may be more effective than the aforementioned techniques based on signal strength indictors at least based on the greater predictability in signal reception when using error detection results. In particular, the use of error detection results to determine the provision of the first receiver may effectively limit the number of consecutive communications lost for the second RAT to a single communication. Namely, with use of the error detection result, any communication for the second RAT that is not successfully decoded may cause the next communication for the second RAT to use the first receiver. Use of the first receiver may be expected to cause successful reception of the next communication for the second RAT. As such, while the use of error detection results in this way may allow a first communication for the second RAT to be lost, it is expected that the next communication for the second RAT will not be lost. This thereby may result in an expectation that a maximum of one consecutive communication will be lost for the second RAT. On the other hand, techniques using signal strength indicators may lack this predictability. For example, consider a scenario in which a UE receives a first communication for the second RAT on the second receiver while simultaneously determining a signal strength indicator. In this case, the UE may fail to successfully recover the information bits of the first communication (e.g., due to desense, randomness in downlink noise, etc.) even though the signal strength indicator is at or above a predetermined acceptable threshold. Then, for the next communication for the second RAT, the UE may provide the second receiver. But, due to a drop in signal strength for the second RAT, the next communication may also be lost. Therefore, two consecutive communications for the second RAT may be lost. This may be a common scenario, but more uncommon scenarios (e.g., signal strength indicator consistently just above acceptable threshold, channel signal quality rapidly improving and degrading) may cause even greater consecutive losses of communications for the second RAT. Therefore, techniques using error detection results may be more effective than techniques using signal strength indicators because the latter may not be able to provide an expected upper bound on consecutive communication loss. 
     With reference to  FIG. 1 , a schematic diagram of a system  100  is shown in accordance with various embodiments. The system  100  may include a UE  110 , a first base station  120 , and a second base station  130 . In some embodiments, each of the first base station  120  and the second base station  130  may represent a separate RAT, such as GSM, CDMA, CDMA2000, TD-CDMA, TD-SCDMA, W-CDMA, TDMA, FDMA, LTE, Wi-Fi, various 3G standards, various 4G standards, and/or the like. In other words, the first base station  120  may represent a first RAT, and the second base station may represent a second RAT, where the first RAT and the second RAT are different RATs. By way of illustrating with a non-limiting example, the first base station  120  may be transmitting W-CDMA while the second base station  130  may be transmitting GSM. In some embodiments, each RAT may be transmitted by the associated base station at different physical locations (i.e., the first base station  120  and the second base station  130  may be at different locations). In other embodiments, each RAT may be transmitted by the associated base station at the same physical location (i.e., the first base station  120  and the second base station  130  may be physically joined, or the base stations are the same base station). 
     The first base station  120  and the second base station  130  may each include at least one antenna group or transmission station located in the same or different areas, where the at least one antenna group or transmission station may be associated with signal transmission and reception. The first base station  120  and the second base station  130  may each include one or more processors, modulators, multiplexers, demodulators, demultiplexers, antennas, and the like for performing the functions described herein. In some embodiments, the first base station  120  and the second base station  130  may be utilized for communication with the UE  110  and may be an access point, Node B, evolved Node B (eNode B or eNB), base transceiver station (BTS), or the like. 
     A cell  140  may be an area associated with the first base station  120  and the second base station  130 , such that the UE  110 , when located within the cell  140 , may connect to or otherwise access both the first and second RATs, as supported by the first base station  120  and the second base station  130  (e.g., receive signals from and transmit signals to the first base station  120  and the second base station  130 ), respectively. The cell  140  may be a defined area, or may refer to an undefined area in which the UE  110  may access the RATs supported by the base stations  120 ,  130 . 
     In various embodiments, the UE  110  may be configured to access the RATs from the first base station  120  and/or the second base station  130  (e.g., receive/transmit signals of the first and/or the second RAT from/to the first base station  120  and/or the second base station  130 ). The UE  110  may be configured to access the RATs by virtue of the multi-SIM and/or the multi-mode SIM configuration of the UE  110  as described, such that when a SIM corresponding to a RAT is received, the UE  110  may be allowed to access that RAT, as provided by the associated base station. 
     In general, an acquisition process of a RAT refers to the process in which the UE  110  searches and acquires various communication protocols of the RAT in order to acquire and establish communication or traffic with the target base node that is broadcasting the RAT. Some communication protocols include synchronization channels, such as, but not limited to, primary synchronization channel (“P-SCH”), secondary synchronization channel (“S-SCH”), common pilot channel (“CPICH”), and the like. The target base nodes are nodes that transmit, broadcast, or otherwise support the particular RAT being acquired. In some embodiments, the first base station  120  may be a target base node for the first RAT, given that the first RAT may be transmitted by the first base station  120  as described. Thus, when the UE  110  initiates an acquisition process of the first RAT (as supported by the first base station  120 ), a communication channel is set for future communication and traffic between the UE  110  and the first base station  120 . Similarly, the second base station  130  may be a target base node for the second RAT, which is transmitted by the second base station  130  as described. Thus, when the UE  110  initiates an acquisition process of the second RAT, a communication channel is set for future communication and traffic between the UE  110  and the second base station  130 . The acquisition process may be initiated when the UE  110  seeks to initially access the RAT, or, after attaching to an initial RAT, to identify candidate target RAT (that is not the initial RAT) for a handover. 
     It should be appreciated by one of ordinary skill in the art that  FIG. 1  and its corresponding disclosure are for illustrative purposes, and that the system  100  may include three or more base stations. In some embodiments, three or more base stations may be present, where each of the three or more base stations may represent (i.e., transmits signals for) one or more separate RATs in the manner such as, but not limited to, described herein. 
       FIG. 2  is a functional block diagram of a UE  200  suitable for implementing various embodiments. According to various embodiments, the UE  200  may be the same or similar to the UE  110  as described with reference to  FIG. 1 . With reference to  FIGS. 1-2 , the UE  200  may include at least one processor  201 , memory  202  coupled to the processor  201 , a user interface  203 , RF resources  204 , and one or more SIMs (as denoted SIM A  206  and SIM B  207 ). 
     The processor  201  may include any suitable data processing device, such as a general-purpose processor (e.g., a microprocessor), but in the alternative, the processor  201  may be any suitable electronic processor, controller, microcontroller, or state machine. The processor  201  may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, at least one microprocessor in conjunction with a DSP core, or any other such configuration). The memory  202  may be operatively coupled to the processor  201  and may include any suitable internal or external device for storing software and data for controlling and use by the processor  201  to perform operations and functions described herein, including, but not limited to, random access memory RAM, read only memory ROM, floppy disks, hard disks, dongles or other USB connected memory devices, or the like. The memory  202  may store an operating system (“OS”), as well as user application software and executable instructions. The memory  202  may also store application data, such as an array data structure. 
     The user interface  203  may include a display and a user input device. In some embodiments, the display may include any suitable device that provides a human-perceptible visible signal, audible signal, tactile signal, or any combination thereof, including, but not limited to a touchscreen, LCD, LED, CRT, plasma, or other suitable display screen, audio speaker or other audio generating device, combinations thereof, and the like. In various embodiments, the user input device may include any suitable device that receives input from the use, the user input device including, but not limited to one or more manual operator (such as, but not limited to a switch, button, touchscreen, knob, slider or the like), microphone, camera, image sensor, and the like. 
     The processor  201  and the memory  202  may be coupled to the RF resources  204 . In some embodiments, the RF resources  204  may be one set of RF resources such that only one RAT may be supported by the set of RF resources at any given time. In other embodiments, the RF resources may be a plurality of sets of RF resources, such that each set may support one RAT at a given time, thus enabling the UE  200  to support multiple RATs simultaneously, (e.g., in a MSMA case). The RF resources  204  may include at least one baseband-RF resource chain (with which each SIM in the UE  200 , e.g., the SIM A  206  and the SIM B  207 , may be associated). The baseband-RF resource chain may include a baseband modem processor  205 , which may perform baseband/modem functions for communications on at least one SIM, and may include one or more amplifiers and radios. In some embodiments, baseband-RF resource chains may share the baseband modem processor  205  (i.e., a single device that performs baseband/modem functions for all SIMs on the UE  200 ). In other embodiments, each baseband-RF resource chain may include physically or logically separate baseband processors  205 . 
     The RF resources  204  may include transceivers that perform transmit/receive functions for the associated SIM of the UE  200 . The RF resources  204  may include separate transmit and receive circuitry, such as a separate transmitter and receiver, or may include a transceiver that combines transmitter and receiver functions. The RF resources  204  may each be coupled to a wireless antenna. 
     In some embodiments, the processor  201 , the memory  202 , and the RF resources  204  may be included in the UE  200  as a system-on-chip. In some embodiments, the one or more SIMs (e.g., SIM A  206  and SIM B  207 ) and their corresponding interfaces may be external to the system-on-chip. Further, various input and output devices may be coupled to components on the system-on-chip, such as interfaces or controllers. 
     The UE  110  is configured to receive one or more SIMs (e.g., SIM A  206  and SIM B  207 ), an example of which is described herein. A SIM in various embodiments may be a Universal Integrated Circuit Card (UICC) that is configured with SIM and/or USIM applications, enabling access to various RAT networks as described. The UICC may also provide storage for a phone book and other applications. Alternatively, in a CDMA network, a SIM may be a UICC removable user identity module (R-UIM) or a CDMA subscriber identity module (CSIM) on a card. 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 UE  200 , 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 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&#39;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 PLMN (HPLMN) code, etc.) to indicate the SIM card network operator provider. 
     In some embodiments, the UE  200  may include a first SIM interface (not shown) that may receive a first SIM (e.g., SIM A  206 ), which may be associated with one or more RATs. In addition, the UE  200  may also include a second SIM interface (not shown) that may receive a second SIM (e.g., SIM B  207 ), which may be associated with one or more RATs that may be different (or the same in some cases) than the one or more RATs associated with SIM A  206 . Each SIM may enable a plurality of RATs by being configured as a multi-mode SIM, as described herein. In some embodiments, a first RAT enabled may be a same or different RAT as a second RAT (e.g., a DSDS device may enable two RATs), for example where both of them may be GSM, or one of them may be GSM and the other may be W-CDMA. In addition, two RATs (which may be the same or different) may each be associated with a separate subscription, or both of them may be associated with a same subscription. For example, a DSDS device may enable LTE and GSM, where both of the RATs enabled may be associated with a same subscription, or, in other cases, LTE may be associated with a first subscription and GSM may be associated with a second subscription different from the first subscription. 
     In embodiments in which the UE  200  comprises a smart phone, or the like, the UE  200  may have existing hardware and software for telephone and other typical wireless telephone operations, as well as additional hardware and software for providing functions as described herein. Such existing hardware and software includes, for example, one or more input devices (such as, but not limited to keyboards, buttons, touchscreens, cameras, microphones, environmental parameter or condition sensors), display devices (such as, but not limited to electronic display screens, lamps or other light emitting devices, speakers or other audio output devices), telephone and other network communication electronics and software, processing electronics, electronic storage devices and one or more antennae and receiving electronics for receiving various RATs. In such embodiments, some of that existing electronics hardware and software may also be used in the systems and processes for functions as described herein. 
     Accordingly, such embodiments can be implemented with minimal additional hardware costs. However, other embodiments relate to systems and process that are implemented with dedicated device hardware (UE  200 ) specifically configured for performing operations described herein. Hardware and/or software for the functions may be incorporated in the UE  200  during manufacturing, for example, as part of the original equipment manufacturer&#39;s (“OEM&#39;s”) configuration of the UE  200 . In further embodiments, such hardware and/or software may be added to the UE  200 , after manufacturing of the UE  200 , such as by, but not limited to, installing one or more software applications onto the UE  200 . 
     In some embodiments, the UE  200  may include, among other things, additional SIM(s), SIM interface(s), additional RF resource(s) (i.e., sets of RF resources) associated with the additional SIM(s), and additional antennae for connecting to additional RATs supported by the additional SIMs. 
     Embodiments may be implemented in a UE that performs tune-away or other similar procedures to support communication with multiple RATs. In particular, embodiments may be implemented in a UE capable of concurrently communicating with more than one RAT on a single RF chain, (i.e., a single receiver/transmitter module). For example, a UE may be configured to communicate with both the AT&amp;T W-CDMA network and the Verizon CDMA2000 network. 
       FIG. 3  is a schematic diagram illustrating an example of a UE  300  according to various embodiments. With reference to  FIGS. 1-3 , the UE  300  may correspond to the UE  110 ,  200 . According to some embodiments, the UE  300  may include: SIM  1   312 , SIM  2   314 , system on a chip  320 , transceiver  330 , transmitter  332 , first receiver  334 , second receiver  336 , antennas  340 , first antenna  342 , second antenna  344 , connection  352 , connection  354 , and connection  356 . 
     In some embodiments, the SIM  1   322  and the SIM  2   314  may be subscriber identity modules that provide subscriptions for multiple RATs. The SIM  1   312  and the SIM  2   314  may be provided similar to the SIM A  206  and the SIM B  207 . 
     In some embodiments, the system on a chip  320  may include various components used for the operation of the UE  300 , such as a processor, memory, and some RF resources. The system on a chip  320  may be provided as a combination of the processor  201 , the memory  202 , and portions of the RF resources  204 . With respect to RF resources, the system on a chip  320  may be configured to contain components related to a modem functionality but not components related to transceiver functionality. For example, the system on a chip  320  may contain modulation and demodulation components. The system on a chip  320  may be configured to decode packets received by the UE  300 , such as packets received by the first receiver  334  and/or the second receiver  336 . The system on a chip  320  may be coupled to the transceiver  330  by the connections  352 ,  354 ,  356 . 
     In some embodiments, the transceiver  330  may include the transmitter  332 , the first receiver  334 , and the second receiver  336 . In order to support communication using multiple RATs, the transceiver  330  may support active use of the transmitter  332 , the first receiver  334 , and the second receiver  336  for an active connection on a first RAT, while occasionally switching the use of the second receiver  336  for an idle connection on a second RAT. 
     According to some embodiments, the first receiver  334  and the second receiver  336  may have respective sensitivities, which may be different. Generally, the sensitivity of a receiver may be defined as the minimum signal power required at the input of the receiver in order to produce a signal with a particular signal-to-noise ratio at the output of the receiver. In some embodiments, the first receiver  334  may have a greater sensitivity than the second receiver  336  may have. The first receiver  334  may be said to have a greater sensitivity if the first receiver  334  has a lower minimum signal power requirement than the second receiver  336 , based on a same particular signal-to-noise-ratio value for the outputs of the receivers. In this way, a receiver may be said to have a greater sensitivity if it can receive a weaker input signal while still producing a predefined signal-to-noise ratio for an output signal, as compared to some other receiver. In some situations, a “greater” sensitivity may also be referred to as a “better” sensitivity or a “higher” sensitivity. 
     According to some embodiments, the first receiver  334  may be a primary receiver and the second receiver  336  may be a secondary receiver. In such embodiments, the first receiver  334  may be part of a primary RF chain for the transmission and reception of signals (e.g., along with the transmitter  332 ). In some embodiments, the second receiver  336  may function as a diversity receiver for the first receiver  334 . In such embodiments, the second receiver  336  may provide a spatially diverse signal with respect to the signal received by the first receiver  334 . As such, the second receiver  336  may provide spatial diversity to the first receiver  334 . In some embodiments, the first receiver  334  and the second receiver  336  may be otherwise provided. For example, the first receiver  334  may be a diversity receiver and the second receiver  336  may be a primary receiver. 
     According to some embodiments, the UE  300  may support multiple-input and multiple-output (“MIMO”) communications using the transceiver  330 . In such embodiments, the antennas  340  including the first antenna  342  and the second antenna  344  may be a MIMO pair of antennas. Furthermore, the first receiver  334  and the second receiver  336  may be a MIMO pair of receivers. For example, the UE  300  may be configured to receive two MIMO layers in a downlink transmission (e.g., from an evolved node B (“eNodeB”), base stations  120 ,  230 ). In order to receive the two MIMO layers, the UE  300  may be configured to receive communications on the first receiver  334  using the first antenna  342 , and the UE  300  may be configured to receive communications on the second receiver  336  using the second antenna  344 . The transceiver  330  may provide the signals received on the first receiver  334  and the second receiver  336  (e.g., using connections  354 ,  356 ) as input to the system on a chip  320 . The system on a chip  320  may then recover the information bits in the two MIMO layers by decoding the signals received on the first receiver  334  and the second receiver  336 . The UE  300  may support other MIMO and non-MIMO configurations in various embodiments. 
     According to some embodiments, a “rank” may indicate the configuration of the downlink transmission channel to the UE  300 . In particular, in embodiments where the UE  300  is configured to support multiple downlink transmission/reception configurations, the rank may indicate which configuration is being used by the base station (e.g., base station  120 ) and/or the UE  300 . When the base station is transmitting a signal with two MIMO layers in the downlink to the UE  300 , the base station may be said to be using rank  2 . When the base station is transmitting a signal with only one symbol or layer, and thus not using MIMO due to the lack of “multiple-output,” the base station may be said to be using rank  1 . When the UE  300  is receiving the downlink signal using both the first receiver  334  and the second receiver  336 , the UE  300  may be said to be using rank  2 . When the UE  300  is receiving the downlink signal using only one receiver (e.g., the first receiver  334 ), the UE  300  may be said to be using rank  1 . In general, the UE  300  may be configured to receive using the same rank as the base station (e.g., base station  120 ) is using to transmit. The UE  300  may support other ranks and downlink channel configurations in various embodiments. 
       FIG. 4  is a schematic diagram  400  illustrating a communication sequence according to various embodiments. The communication sequence of  FIG. 4  may be illustrative of a communication sequence that can be performed using the UE  300  of  FIG. 3  (which may be similar to the UEs  110 ,  200  of  FIGS. 1-2 ). Similar to  FIG. 3 , the first receiver  334  and the second receiver  336  are shown. With reference to  FIGS. 1-4 , the communication sequence progresses in time from time  470  to time  480  as indicated by time legend  402 . 
     At the time  470 , the first receiver  334  is receiving communications for RAT  1  as indicated by time block  410 . Also, the second receiver  336  is receiving communications for RAT  1  as indicated by time block  430 . At time  472 , communication for RAT  1  is stopped, paused, or otherwise suspended on the second receiver  336 . At or after the time  472 , the second receiver  336  receives communications for RAT  2  as indicated by time block  432 . At time  474 , communication for RAT  2  is stopped on the second receiver  336 . At or after the time  474 , the second receiver  336  starts, unpauses, or otherwise resumes communication for RAT  1  as indicated by time block  434 . The reception of communication for RAT  2  as indicated by the time block  432  may include reception of a first communication for RAT  2 . The reception of communication for RAT  2  as indicated by the time block  432  may be performed in accordance with a scheduled tune-away operation of the second receiver  336  from RAT  1  to RAT  2 . Notably, the reception of communication for RAT  1  on the first receiver  334  continues between the time  472  and the time  474  as indicated by the time block  410 . 
     At or after the time  474  but before time  476 , the UE  300  may calculate an error detection result for the communication received for RAT  2  during the time block  432 . The error detection result may be the result of an error detection scheme or encoding applied to information bits prior to transmission of the communication received during the time block  432 . The error detection result may indicate whether or not one or more bits received during the time block  432  were received in error. The error detection result may indicate whether or not all information bits included in the communication received at the time block  432  could be successfully recovered. In some embodiments, the error detection result may be calculated after a decoding operation was performed for the communication received during the time block  432 . In some embodiments, the error detection result may be calculated after an error correction operation was performed for the communication received during the time block  432 . In some embodiments, the error detection result may indicate whether or not a block error was detected in the communication received during the time block  432 . In some embodiments, the error detection result may be calculated based on application of a cyclic redundancy check (“CRC”) algorithm to a block of data received as part of the communication received during the time block  432 . In various embodiments, the error detection result may be otherwise calculated, generated, or determined. 
     At or after the time  474  but before time  476 , the UE may use the error detection result to determine the provision of the first receiver  334  and the second receiver  336  at the time  476 . If the error detection result indicates an error in the communication received for RAT  2  during the time block  432 , then the UE may determine to provide the first receiver  334  for use for reception of a communication for RAT  2  at the time  476 . If the error detection result does not indicate an error in the communication received for RAT  2  during the time block  432 , then the UE may determine to provide the second receiver  336  for use for reception of a communication for RAT  2  at the time  476 . 
     In the diagram  400 , the error detection result may indicate that no error was detected in the communication received for RAT  2  during the time block  432 . As such, the UE may provide the second receiver  336  for reception of communication for RAT  2  at the time  476 . Accordingly, at the time  476 , communication for RAT  1  is stopped, paused, or otherwise suspended on the second receiver  336 . At or after the time  476 , the second receiver  336  receives communications for RAT  2  as indicated by time block  436 . At time  478 , communication for RAT  2  is stopped on the second receiver  336 . At or after the time  478 , the second receiver  336  starts, unpauses, or otherwise resumes communication for RAT  1  as indicated by time block  438 . Notably, the reception of communication for RAT  1  on the first receiver  334  continues between the time  476  and the time  478  as indicated by the time block  410 . The diagram  400  ends at the time  480 . 
       FIG. 5  is a schematic diagram  500  illustrating a communication sequence according to various embodiments. The communication sequence of  FIG. 5  may be illustrative of a communication sequence that can be performed using the UE  300  of  FIG. 3  (which may be similar to the UEs  110 ,  200  of  FIGS. 1-2 ). Similar to  FIG. 3 , the first receiver  334  and the second receiver  336  are shown. With reference to  FIGS. 1-5 , the communication sequence progresses in time from time  570  to time  580  as indicated by time legend  502 . 
     At time  570 , the first receiver  334  is receiving communications for RAT  1  as indicated by time block  510 . Also, the second receiver  336  is receiving communications for RAT  1  as indicated by time block  530 . At time  572 , communication for RAT  1  is stopped, paused, or otherwise suspended on the second receiver  336 . At or after the time  572 , the second receiver  336  receives communications for RAT  2  as indicated by time block  532 . At time  574 , communication for RAT  2  is stopped on the second receiver  336 . At or after the time  474 , the second receiver  336  starts, unpauses, or otherwise resumes communication for RAT  1  as indicated by time block  534 . The reception of communication for RAT  2  as indicated by the time block  532  may include reception of a first communication for RAT  2 . The reception of communication for RAT  2  as indicated by the time block  532  may be performed in accordance with a scheduled tune-away operation of the second receiver  336  from RAT  1  to RAT  2 . Notably, the reception of communication for RAT  1  on the first receiver  334  continues between the time  572  and the time  574  as indicated by the time block  510 . 
     At or after the time  574  but before time  576 , the UE  300  may calculate an error detection result for the communication received for RAT  2  during the time block  532 . The error detection result may be the result of an error detection scheme or encoding applied to information bits prior to transmission of the communication received during the time block  532 . The error detection result may indicate whether or not one or more bits received during the time block  532  were received in error. The error detection result may indicate whether or not all information bits included in the communication received at the time block  532  could be successfully recovered. In some embodiments, the error detection result may be calculated after a decoding operation was performed for the communication received during the time block  532 . In some embodiments, the error detection result may be calculated after an error correction operation was performed for the communication received during the time block  532 . In some embodiments, the error detection result may indicate whether or not a block error was detected in the communication received during the time block  532 . In some embodiments, the error detection result may be calculated based on application of a cyclic redundancy check (“CRC”) algorithm to a block of data received as part of the communication received during the time block  532 . In various embodiments, the error detection result may be otherwise calculated, generated, or determined. 
     At or after the time  574  but before time  576 , the UE may use the error detection result to determine the provision of the first receiver  334  and the second receiver  336  at the time  576 . If the error detection result indicates an error in the communication received for RAT  2  during the time block  532 , then the UE may determine to provide the first receiver  334  for use for reception of a communication for RAT  2  at the time  576 . If the error detection result does not indicate an error in the communication received for RAT  2  during the time block  532 , then the UE may determine to provide the second receiver  336  for use for reception of a communication for RAT  2  at the time  576 . 
     In the diagram  500 , the error detection result may indicate that an error was detected in the communication received for RAT  2  during the time block  532 . As such, the UE may provide the first receiver  334  and the second receiver  336  for reception of communication for RAT  2  at the time  576 . Accordingly, at the time  576 , communication for RAT  1  is stopped, paused, or otherwise suspended on the first receiver  334 . In addition, at the time  576 , communication for RAT  1  is stopped, paused, or otherwise suspended on the second receiver  336 . At or after the time  576 , the first receiver  334  receives communications for RAT  2  as indicated by time block  512 . At or after the time  576 , the second receiver  336  receives communications for RAT  2  as indicated by time block  536 . At time  578 , communication for RAT  2  is stopped on the first receiver  334  and the second receiver  336 . At or after the time  578 , the first receiver  334  starts, unpauses, or otherwise resumes communication for RAT  1  as indicated by time block  514 . At or after the time  578 , the second receiver  336  starts, unpauses, or otherwise resumes communication for RAT  1  as indicated by time block  538 . The diagram  500  ends at the time  580 . 
     Though particular examples of communication sequences have been shown in the preceding figures, variations from examples are possible in various embodiments. For example, in the embodiments described with reference to diagram  500 , the UE  300  may determine to provide only the first receiver  334  and not the second receiver  336  for reception of communications for RAT  2  between the time  576  and the time  578 . As such, between the time  576  and the time  578 , the second receiver  336  may continue receiving communications for RAT  1 . In such a case, the time block  534  would continue until the time  580 , and the time blocks  536  and  538  would be omitted. Other variations are possible in various embodiments. 
       FIG. 6  is a flowchart of a process  600  according to various embodiments. With reference to  FIGS. 1-6 , the process  600  may be performed by a UE (e.g., the UEs  110 ,  200 ,  300 ). In various embodiments, the operations of the process  600  may be implemented by one or more processors of the UE, such as the processor  201 , the baseband processor(s)  205 , the system on chip  320 , a separate controller (not shown), or the like. 
     At block  602 , communication is performed using RAT  1  on a first receiver. The block  602  may include the first receiver (e.g., the first receiver  334 ) receiving communications for RAT  1 , with RAT  1  being in an active mode, a connected state, or in some other condition requiring constant access to RF resources. 
     At block  604 , a first communication for RAT  2  is received on a second receiver. The block  602  may include the second receiver (e.g., the second receiver  336 ) receiving communications for RAT  2 , with RAT  2  being in an idle mode, a camped state, or in some other condition requiring only intermittent access to RF resources. 
     At block  606 , a determination is made as to whether to receive a second communication for RAT  2  on the first receiver. According to various embodiments, the determination may be made based on an error detection result for the first communication for RAT  2 . The block  606  may include a computing component (e.g., the processor  201 , the BB processor  205 , the system on a chip  320 , etc.) determining whether the error detection result indicates an error for the first communication for RAT  2 . The block  606  may include the computing component determining to use the first receiver (e.g., the first receiver  334 ) for reception of the second communication for RAT  2  if the error detection result indicates an error for the first communication for RAT  2 . The block  606  may include the computing component determining to not use the first receiver (e.g., the first receiver  334 ) for reception of the second communication for RAT  2  if the error detection result does not indicate an error for the first communication for RAT  2 . The block  606  may include the computing component determining to use the first receiver (e.g., the first receiver  334 ) and the second receiver (e.g., the second receiver  336 ) for reception of the second communication for RAT  2  if the error detection result indicates an error for the first communication for RAT  2 . The block  606  may include the computing component determining to not use the first receiver (e.g., the first receiver  334 ) but instead to use the second receiver (e.g., the second receiver  336 ) for reception of the second communication for RAT  2  if the error detection result does not indicate an error for the first communication for RAT  2 . 
       FIG. 7  is a flowchart of a process  700  according to various embodiments. With reference to  FIGS. 1-7 , the process  700  may be performed by a UE (e.g., the UEs  110 ,  200 ,  300 ). In various embodiments, the operations of the process  700  may be implemented by one or more processors of the UE, such as the processor  201 , the baseband processor(s)  205 , the system on chip  320 , a separate controller (not shown), or the like. 
     At block  702 , communication for RAT  2  is received on a second receiver. The block  702  may include the second receiver (e.g., the second receiver  336 ) receiving communications for RAT  2 , with RAT  2  being in an idle mode, a camped state, or in some other condition requiring only intermittent access to RF resources. In some embodiments, the block  702  may correspond to the block  604  of the process  600 . 
     At block  704 , an error detection result is determined for the RAT  2  communication. The block  704  may include a computing component (e.g., the processor  201 , the BB processor  205 , the system on a chip  320 ) determining the error detection result based on the most recently received communication for RAT  2  (i.e., the most recent performance of block  702  or block  708 ). The block  704  may include the computing component applying an error detection algorithm to determine if a block error existed in the communication received for RAT  2 . 
     At block  706 , a determination is made as to whether the determined error detection result indicates an error for the RAT  2  communication. The block  706  may include a computing component (e.g., the processor  201 , the BB processor  205 , the system on a chip  320 ) determining whether the most recently determined error detection result indicates an error for the most recent communication received for RAT  2 . If the error detection result does not indicate an error for the RAT  2  communication (block  706 : No), the process  700  continues at the block  702 . If the error detection result does indicate an error for the RAT  2  communication (block  706 : Yes), the process  700  continues at block  708 . In some embodiments, the blocks  704  and  706  may correspond to the block  608  of the process  600 . 
     At the block  708 , communication for RAT  2  is received on a first receiver (e.g., the first receiver  334 ). The block  708  may include the first receiver receiving communications for RAT  2 , with RAT  2  being in an idle mode, a camped state, or in some other condition requiring only intermittent access to RF resources. 
       FIG. 8  is a flowchart of a process  800  according to various embodiments. With reference to  FIGS. 1-8 , the process  800  may be performed by a UE (e.g., the UEs  110 ,  200 ,  300 ). In various embodiments, the operations of the process  800  may be implemented by one or more processors of the UE, such as the processor  201 , the baseband processor(s)  205 , the system on chip  320 , a separate controller (not shown), or the like. 
     At block  802 , communication is started for RAT  1  on a first receiver (e.g., the first receiver  334 ). The block  802  may include the first receiver starting reception of communications for RAT  1 , with RAT  1  being in an active mode, a connected state, or in some other condition requiring constant access to RF resources. 
     At block  804 , communication is started for RAT  1  on a second receiver (e.g., the second receiver  336 ). The block  804  may include the second receiver starting reception of communications for RAT  1 , with RAT  1  being in an active mode, a connected state, or in some other condition requiring constant access to RF resources. 
     At block  810 , communication is stopped for RAT  1  on the second receiver. The block  810  may include stopping communication on the second receiver (e.g., the second receiver  336 ) in accordance with provisioning of the second receiver for reception of communications for RAT  2 . The block  810  may include stopping communication on the second receiver (e.g., the second receiver  336 ) in accordance with a scheduled tune-away procedure from RAT  1  to RAT  2 . 
     At block  812 , communication is received for RAT  2  on the second receiver. The block  812  may include the second receiver (e.g., the second receiver  336 ) receiving communications for RAT  2 , with RAT  2  being in an idle mode, a camped state, or in some other condition requiring only intermittent access to RF resources. 
     At block  814 , communication is started for RAT  1  on the second receiver. The block  814  may include restarting communication on the second receiver (e.g., the second receiver  336 ) in order to continue the communication initially started with the block  804 . 
     At block  830 , the communication received for RAT  2  is decoded. The block  830  may include a computing component (e.g., the processor  201 , the BB processor  205 , the system on a chip  320 ) providing the communication received for RAT  2  (i.e., as received at the block  812  or the block  822 ) to a decoder provided as part of or connected to the computing component. In some embodiments, the block  830  may include the application of an error correction algorithm to the communication received for RAT  2 . 
     At block  832 , an error detection result is determined for the communication received for RAT  2 . The block  832  may include a computing component (e.g., the processor  201 , the BB processor  205 , the system on a chip  320 ) determining the error detection result based on the most recently received communication for RAT  2  (i.e., the most recent performance of the  812  or the block  822 ). The block  832  may include the computing component determining the error detection result based on the decoded communication for RAT  2  as decoded with the block  830 . The block  832  may include the computing component applying an error detection algorithm to determine if a block error existed in the communication received for RAT  2 . 
     At block  834 , a determination is made as to whether or not the error detection result indicates an error. The block  834  may include a computing component (e.g., the processor  201 , the BB processor  205 , the system on a chip  320 ) determining whether the most recently determined error detection result indicates an error for the most recent communication received for RAT  2 . If the error detection result does not indicate an error for the RAT  2  communication (block  834 : No), the process  800  continues at the block  810 . If the error detection result does indicate an error for the RAT  2  communication (block  834 : Yes), the process  800  continues at block  820 . 
     At the block  820 , communication is stopped for RAT  1  on the first receiver. The block  820  may include stopping communication on the first receiver (e.g., the first receiver  334 ) in accordance with provisioning of the first receiver for reception of communications for RAT  2 . The block  820  may include stopping communication on the first receiver (e.g., the first receiver  334 ) in accordance with a scheduled tune-away procedure from RAT  1  to RAT  2 . 
     At block  822 , communication is received for RAT  2  on the first receiver. The block  822  may include the first receiver (e.g., the first receiver  334 ) receiving communications for RAT  2 , with RAT  2  being in an idle mode, a camped state, or in some other condition requiring only intermittent access to RF resources. 
     At block  824 , communication is started for RAT  1  on the first receiver. The block  824  may include restarting communication on the first receiver (e.g., the first receiver  334 ) in order to continue the communication initially started with the block  802 . 
     The process  800  may be modified from that just described in various embodiments. For example, a UE (e.g., the UE  300 ) implementing the process  800  may wait a period of time after performing the block  834  and before performing the block  810  or the block  820 . This period of time may be a predefined interval (e.g., a paging interval for RAT  2 ). As another example, if the error detection result is determined to indicate an error at the block  834 , the process  800  may continue at both the block  810  and the block  820 . In such a scenario, both of the first receiver (e.g., the first receiver  334 ) and the second receiver (e.g., the second receiver  336 ) may be used to receive the communication for RAT  2  (i.e., both the block  812  and the block  822  may be performed together). 
       FIG. 9  is a flowchart of a process  900  according to various embodiments. With reference to  FIGS. 1-9 , the process  900  may be performed by a UE (e.g., the UEs  110 ,  200 ,  300 ). In various embodiments, the operations of the process  900  may be implemented by one or more processors of the UE, such as the processor  201 , the baseband processor(s)  205 , the system on chip  320 , a separate controller (not shown), or the like. 
     At block  902 , communication is performed with an LTE RAT using a primary receiver. The block  902  may include a UE (e.g., the UE  300 ) communicating while in a connected mode with an LTE RAT. The block  902  may include the UE using a primary receiver (e.g., the first receiver  334 ) for communication with the LTE RAT. The block  902  may include the UE additionally using a secondary receiver (e.g., the second receiver  336 ) for communication with the LTE RAT. 
     At block  904 , waiting is performed for a CDMA2000 paging interval. The block  904  may include a computing component (e.g., the processor  201 , the BB processor  205 , the system on a chip  320 ) causing the UE (e.g., the UE  300 ) to wait a period of time for a paging interval for a CDMA2000 RAT with which the UE is in communication. The UE may determine the CDMA2000 paging interval based on a slot cycle index (“SCI”) specified by a computing device (e.g., the base station  110 ) included in the radio access network for the CDMA2000 RAT. In some embodiments, the block  904  may overlap in time with the performance of the blocks  922 ,  924 , and  926 . In some embodiments, the block  904  may include waiting for slightly less time than the CDMA2000 paging interval. The block  904  may be performed at the same time or over a same approximate period as the performance of the block  902 . 
     At block  906 , a determination is made as to whether a CRC metric for a last CDMA2000 page indicates an error. The block  906  may include a computing component (e.g., the processor  201 , the BB processor  205 , the system on a chip  320 ) retrieving a stored CRC metric (e.g., as stored at the block  926 ) that indicates whether an error was detected in the most recently received CDMA2000 page. If the CRC metric does indicate an error (block  906 : Yes), then the process  900  continues at block  910 . If the CRC metric does not indicate an error (block  906 : No), then the process  900  continues at block  912 . 
     At the block  910 , the primary receiver is requested for reception of a CDMA2000 page. The block  910  may include a computing component (e.g., the processor  201 , the BB processor  205 , the system on a chip  320 ) requesting the use of the primary receiver (e.g., the first receiver  334 ) for use to receive a future CDMA2000 page. The primary receiver may be allocated for reception of the CDMA2000 page in response to the performance of the block  910 . 
     At the block  912 , the secondary receiver is requested for reception of a CDMA2000 page. The block  912  may include a computing component (e.g., the processor  201 , the BB processor  205 , the system on a chip  320 ) requesting the use of the secondary receiver (e.g., the second receiver  336 ) for use to receive a future CDMA2000 page. The secondary receiver may be allocated for reception of the CDMA2000 page in response to the performance of the block  912 . 
     At block  920 , a CDMA2000 page is received. The block  920  may include using the primary receiver (e.g., the first receiver  334 ) or the secondary receiver (e.g., the second receiver  336 ) as requested at the block  910  or the block  912 , respectively, to receive a communication from the CDMA2000 RAT including the CDMA2000 page. 
     At block  922 , the CDMA2000 page is demodulated. The block  922  may include a computing component (e.g., the processor  201 , the BB processor  205 , the system on a chip  320 ) demodulating the CDMA2000 page received at the block  920 . 
     At block  924 , a CRC metric is calculated. The block  924  may include a computing component (e.g., the processor  201 , the BB processor  205 , the system on a chip  320 ) determining a CRC result for the CDMA2000 page demodulated at the block  922 . The CRC result may indicate whether a block error exists in the demodulated CDMA2000 page. The CRC result may be used as the CRC metric. 
     At block  926 , the CRC metric is stored. The block  926  may include a computing component (e.g., the processor  201 , the BB processor  205 , the system on a chip  320 ) storing the CRC metric calculated at the block  924 . The CRC metric may be stored in a storage component (e.g., the memory  202 , the system on a chip  320 ). The process  900  may repeat by proceeding to the blocks  902  and  904 . 
       FIG. 10  illustrates an example of a UE  1000 , which may correspond to the UEs  110 ,  200 ,  300  in  FIGS. 1-3 . With reference to  FIGS. 1-10 , the UE  1000  may include a processor  1002  coupled to a touchscreen controller  1004  and an internal memory  1006 . The processor  1002  may correspond to the processor  201 . The processor  1002  may be one or more multi-core integrated circuits designated for general or specific processing tasks. The internal memory  1006  may correspond to the memory  202 . The memory  1006  may be volatile or non-volatile memory, and may also be secure and/or encrypted memory, or unsecure and/or unencrypted memory, or any combination thereof. The touchscreen controller  1004  and the processor  1002  may also be coupled to a touchscreen panel  1012 , such as a resistive-sensing touchscreen, capacitive-sensing touchscreen, infrared sensing touchscreen, etc. Additionally, the display of the UE  1000  need not have touch screen capability. The touch screen controller  1004 , the touchscreen panel  1012  may correspond to the user interface  203 . 
     The UE  1000  may have one or more cellular network transceivers  1008   a ,  1008   b  coupled to the processor  1002  and to two or more antennae  1010  and configured for sending and receiving cellular communications. The transceivers  1008  and antennae  1010   a ,  1010   b  may be used with the above-mentioned circuitry to implement the various embodiment methods. The UE  1000  may include two or more SIM cards  1016   a ,  1016   b , corresponding to SIM A  206  and SIM B  207 , coupled to the transceivers  1008   a ,  1008   b  and/or the processor  1002  and configured as described above. The UE  1000  may include a cellular network wireless modem chip  1011  that enables communication via a cellular network and is coupled to the processor. The one or more cellular network transceivers  1008   a ,  1008   b , the cellular network wireless modem chip  1011 , and the two or more antennae  1010  may correspond to the RF resources  204 . 
     The UE  1000  may include a peripheral device connection interface  1018  coupled to the processor  1002 . The peripheral device connection interface  1018  may be singularly configured to accept one type of connection, or multiply configured to accept various types of physical and communication connections, common or proprietary, such as USB, FireWire, Thunderbolt, or PCIe. The peripheral device connection interface  1018  may also be coupled to a similarly configured peripheral device connection port (not shown). 
     The UE  1000  may also include speakers  1014  for providing audio outputs. The UE  1000  may also include a housing  1020 , constructed of a plastic, metal, or a combination of materials, for containing all or some of the components discussed herein. The UE  1000  may include a power source  1022  coupled to the processor  1002 , such as a disposable or rechargeable battery. The rechargeable battery may also be coupled to a peripheral device connection port (not shown) to receive a charging current from a source external to the UE  1000 . The UE  1000  may also include a physical button  1024  for receiving user inputs. The UE  1000  may also include a power button  1026  for turning the UE  1000  on and off. 
     The foregoing method descriptions and the process flow diagrams are provided merely as illustrative examples and are not intended to require or imply that the blocks of various embodiments must be performed in the order presented. As will be appreciated by one of skill in the art the order of blocks in the foregoing embodiments may be performed in any order. Words such as “thereafter,” “then,” “next,” etc. are not intended to limit the order of the blocks; these words are simply used to guide the reader through the description of the methods. Further, any reference to claim elements in the singular, for example, using the articles “a,” “an,” or “the” is not to be construed as limiting the element to the singular. 
     The various illustrative logical blocks, modules, circuits, and algorithm blocks described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and flowchart blocks have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure. 
     The hardware used to implement the various illustrative logics, logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but, in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration). Alternatively, some blocks or methods may be performed by circuitry that is specific to a given function. 
     In some exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a non-transitory computer-readable storage medium or non-transitory processor-readable storage medium. The blocks of a method or algorithm disclosed herein may be embodied in a processor-executable software module which may reside on a non-transitory computer-readable or processor-readable storage medium. Non-transitory computer-readable or processor-readable storage media may be any storage media that may be accessed by a computer or a processor. By way of example but not limitation, such non-transitory computer-readable or processor-readable storage media may include RAM, ROM, EEPROM, FLASH memory, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to store desired program code in the form of instructions or data structures and that may be accessed by a computer. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of non-transitory computer-readable and processor-readable media. Additionally, the operations of a method or algorithm may reside as one or any combination or set of codes and/or instructions on a non-transitory processor-readable storage medium and/or computer-readable storage medium, which may be incorporated into a computer program product. 
     The preceding description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to some embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the following claims and the principles and novel features disclosed herein.