PATENT DOCUMENT

Publication Number: US-9526037-B2
Application Number: US-201414168402-A
Country: US
Kind Code: B2

Title: SRVCC handover indication for remote party to voice call

Abstract:
A method for providing indication of an SRVCC handover is disclosed. The method can include a first wireless communication device participating in a voice call with a second wireless communication device via a connection between the first wireless communication device and a first network. The method can further include the first wireless communication device determining a condition indicative of an impending SRVCC handover of the first wireless communication device from the first network to a legacy network. In response to the condition, the method can additionally include the first wireless communication device formatting a message including an indication that the first wireless communication device is going to perform the SRVCC handover and sending the message to the second wireless communication device prior to performance of the SRVCC handover.

Claims:
What is claimed is: 
     
       1. A method for providing indication of a single radio voice call continuity (SRVCC) handover, the method comprising a first wireless communication device:
 participating in a voice call with a second wireless communication device via a connection between the first wireless communication device and a first network servicing the voice call as a voice over Internet protocol (VoIP) call via a packet switched domain; 
 determining a condition indicative of an impending SRVCC handover of the first wireless communication device from the first network to a legacy network, wherein the legacy network comprises a circuit switched domain configured to service the voice call as a circuit switched call after completion of the SRVCC handover; and 
 in response to the condition:
 formatting a message comprising an advance indication that the first wireless communication device is going to perform the SRVCC handover; and 
 sending the message to the second wireless communication device prior to performance of an SRVCC procedure that includes the SRVCC handover in conjunction with the first network and the legacy network, 
 
 wherein the condition is based on signal quality parameters and/or loading level parameters. 
 
     
     
       2. The method of  claim 1 , wherein the message comprises a voice packet comprising voice data for the voice call and the advance indication. 
     
     
       3. The method of  claim 2 , wherein the voice packet comprises a real-time transport protocol (RTP) packet, and wherein the advance indication is included in a payload header of the RTP packet. 
     
     
       4. The method of  claim 1 , wherein the message comprises a dedicated signaling message that is sent separately from voice packets comprising voice data for the voice call. 
     
     
       5. The method of  claim 1 , wherein determining the condition comprises determining the condition based at least in part on a deterioration in signal quality of the first network. 
     
     
       6. The method of  claim 1 , wherein determining the condition comprises determining the condition based at least in part on a measured signal quality of the legacy network. 
     
     
       7. The method of  claim 1 , wherein determining the condition comprises determining the condition based at least in part on a loading level on a serving base station of the first network. 
     
     
       8. The method of  claim 1 , wherein determining the condition comprises determining that Transmit Time Interval (TTI) bundling has been activated. 
     
     
       9. The method of  claim 1 , wherein the first network comprises a network implementing a Long Term Evolution (LTE) technology, and wherein the voice call is serviced as a Voice over LTE (VoLTE) call on the first network. 
     
     
       10. A wireless communication device comprising:
 at least one transceiver, the at least one transceiver configured to send wireless signals to and receive wireless signals from a first network and a legacy network; and 
 processing circuitry coupled with the at least one transceiver, wherein the processing circuitry is configured to cause the wireless communication device to at least: 
 participate in a voice call with a second wireless communication device via a connection between the wireless communication device and the first network; 
 determine a condition indicative of an impending SRVCC handover of the wireless communication device from the first network to the legacy network; and 
 in response to the condition:
 format a message comprising an advance indication that the wireless communication device is going to perform the SRVCC handover; and 
 send the message to the second wireless communication device prior to performance of an SRVCC procedure that includes the SRVCC handover in conjunction with the first network and the legacy network. 
 
 
     
     
       11. The wireless communication device of  claim 10 , wherein the message comprises a voice packet comprising voice data for the voice call and the advance indication. 
     
     
       12. The wireless communication device of  claim 10 , wherein the processing circuitry is further configured to cause the wireless communication device to determine the condition based at least in part on one or more of a deterioration in signal quality of the first network or a measured signal quality of the legacy network. 
     
     
       13. The wireless communication device of  claim 10 , wherein the processing circuitry is further configured to cause the wireless communication device to determine the condition based at least in part on a loading level on a serving base station of the first network. 
     
     
       14. The wireless communication device of  claim 10 , wherein the processing circuitry is further configured to cause the wireless communication device to determine the condition in response to activation of Transmit Time Interval (TTI) bundling. 
     
     
       15. A method for preparing for a remote single radio voice call continuity (SRVCC) handover, the method comprising a first wireless communication device:
 participating in a voice call with a second wireless communication device; 
 receiving an advance indication from the second wireless communication device that the second wireless communication device is going to perform an SRVCC procedure that includes an SRVCC handover; and 
 in response to receiving the advance indication, modifying a configuration parameter of a de-jitter buffer of the first wireless communication device, the de-jitter buffer containing at least one voice packet received for the voice call in advance of the SRVCC handover of the second wireless communication device. 
 
     
     
       16. The method of  claim 15 , wherein receiving the advance indication comprises receiving a voice packet comprising voice data for the voice call and the advance indication. 
     
     
       17. The method of  claim 16 , wherein the voice packet comprises a real-time transport protocol (RTP) packet, and wherein the advance indication is included in a payload header of the RTP packet. 
     
     
       18. The method of  claim 15 , wherein receiving the advance indication comprises receiving an advance indication included in a dedicated signaling message sent separately from voice packets comprising voice data for the voice call. 
     
     
       19. The method of  claim 15 , wherein modifying the configuration parameter of the de-jitter buffer comprises increasing a size of the de-jitter buffer. 
     
     
       20. The method of  claim 15 , wherein modifying the configuration parameter of the de-jitter buffer comprises modifying an amount of time warping applied to one or more voice packets queued in the de-jitter buffer.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority from U.S. Provisional Patent Application No. 61/760,579, filed on Feb. 4, 2013, which is hereby incorporated herein by reference in its entity. 
    
    
     FIELD 
     The described embodiments relate generally to wireless communications technology. More particularly, the present embodiments relate to provision of an indication that a first device participating in a voice call is going to perform a single radio voice call continuity (SRVCC) handover to a second device participating in the voice call. 
     BACKGROUND 
     Cellular networks using newer radio access technologies (RATs), such as Long Term Evolution (LTE), are being developed and deployed. Networks using these newer RATs have packet switched (PS) domains configured to support PS voice calls, such as via voice over Internet Protocol (VoIP). As coverage of newer networks such as LTE networks is not universal, networks using newer RATs are often co-deployed with legacy RATs, such as second generation (2G) and third generation (3G) RATs, including Universal Mobile Telecommunications System (UMTS) networks and Global System for Mobile Communications (GSM) networks, which only support voice calls via a circuit switched (CS) domain. Accordingly, a wireless communication device can be handed over between a network, such as an LTE network, supporting PS voice calls and a legacy network supporting voice calls via a CS domain as coverage or other conditions may dictate. For example, where LTE coverage is running out, the LTE network can redirect a device to a legacy network in response to the device moving out of the coverage range of the LTE network. 
     A device having an active voice call supported by a PS domain of an LTE network or other network supporting PS voice calls may have to perform a handover to a legacy network during the voice call due to mobility outside of a coverage area of the serving network or other network conditions, which may merit handover. SRVCC has been defined as a procedure to allow an active voice call to be moved from a PS domain to a CS domain of a legacy network during handover of a device to a legacy network. Presently, only the device redirected to the legacy network is aware of occurrence of the SRVCC handover. As such, a device participating in the voice call can be unaware that a remote device participating in the voice call is participating in an SRVCC procedure. SRVCC is a relatively complicated and time consuming procedure on the network side. Due to the complexity of SRVCC, a device participating in a voice call via voice over LTE (VoLTE) or other VoIP connection while a remote device is performing an SRVCC handover can experience an interruption of voice packets in both uplink (UL) and downlink (DL) directions for up to 300 milliseconds, which can negatively impact user experience. 
     SUMMARY 
     Some example embodiments provide advance notification of a remote SRVCC handover to a device participating in a voice call. More particularly, in accordance with some such example embodiments, a first device participating in a voice call can be configured to determine a condition indicative of an impending SRVCC handover and, in response thereto, can inform a second device participating in the voice call of the impending SRVCC handover prior to performance of the SRVCC handover. The second device of such example embodiments can be configured to prepare for the remote SRVCC handover by adapting the de-jitter buffer to provide for better user experience during any interruption in transfer of voice packets during the remote SRVCC procedure. Accordingly, user experience can be improved through better audio continuity during the remote SRVCC handover. 
     This Summary is provided merely for purposes of summarizing some example embodiments so as to provide a basic understanding of some aspects of the disclosure. Accordingly, it will be appreciated that the above described example embodiments are merely examples and should not be construed to narrow the scope or spirit of the disclosure in any way. Other embodiments, aspects, and advantages will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the described embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1  illustrates an example wireless communication system in accordance with some example embodiments; 
         FIG. 2  illustrates a block diagram of an apparatus that can be implemented on a wireless communication device in accordance with some example embodiments; 
         FIG. 3  illustrates a flowchart of an example method for providing an indication of an impending SRVCC handover in accordance with some example embodiments; 
         FIG. 4  illustrates a flowchart of another example method for preparing for a remote SRVCC handover in accordance with some example embodiments; and 
         FIG. 5  illustrates a signaling diagram in accordance with some example embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     Some example embodiments provide advance notification of a remote SRVCC handover to a device participating in a voice call. More particularly, in accordance with some example embodiments, a first device participating in a voice call can be configured to determine a condition indicative of an impending SRVCC handover and, in response thereto, can send a message comprising an indication of the impending SRVCC handover to a second device participating in the voice call prior to performance of the SRVCC handover. The second device of such example embodiments can receive the message and can be configured to respond to the indication by adapting the de-jitter buffer in preparation for the remote SRVCC handover. For example, in accordance with some embodiments, the second device can modify a configuration parameter of the de-jitter buffer to provide better audio continuity during any interruption in transfer of voice packets that may occur during the SRVCC procedure. In this regard, the advance notice of the remote SRVCC procedure provided by some example embodiments can enable the second device to prepare for the SRVCC handover, thereby improving user experience through better audio continuity during the remote SRVCC handover. 
     These and other embodiments are discussed below with reference to  FIGS. 1-5 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these Figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1  illustrates an example wireless communication system in accordance with some example embodiments. The system  100  can include Device A  102  and Device B  104 . Device A  102  can be embodied as a wireless communication device. By way of non-limiting example, Device A  102  can be embodied as a cellular phone, such as a smart phone device, a tablet computing device, a laptop computing device, and/or other computing device that can be configured (e.g., via hardware and/or software) to wirelessly access a network and engage in a voice call. 
     In some example embodiments, Device B  104  can also be embodied as a wireless communication device. For example, Device B  104  can be embodied as a cellular phone, such as a smart phone device, a tablet computing device, a laptop computing device, and/or other computing device that can be configured (e.g., via hardware and/or software) to wirelessly access a network and engage in a voice call. It will be appreciated, however, that in some example embodiments, Device B  104  can be embodied as a computing device configured to access a network via a wireline connection to enable participation in a voice call with the device A  102 . For example, in some such embodiments in which Device B  104  is configured to access a network via a wireline connection, Device B  104  can be embodied as a computing device, such as a desktop computing device, laptop computing device, or other computing device, that can access (e.g., via the Internet) and/or execute an application supporting VoIP calls to enable the computing device to support a voice call with Device A  102 . As such, it will be appreciated that techniques described herein with respect to embodiments in which Device B  104  is embodied as a wireless communication device can be applied mutatis mutandis to embodiments in which Device B  104  is connected to an access network and participating in a voice call via a wireline connection. 
     Device B  104  can be connected to a network  110  (e.g., via an access network), which can be configured to facilitate communication between Device B  104  and Device A  102 . In this regard, the network  110  can be embodied as any network or combination of networks that can enable communication between Device B  104  and a cellular radio access network, such as the first network  106  and legacy network  108 , which can be accessed via Device A  102  so as to support a voice call between Device A  102  and Device B  104 . For example, the network  110  can comprise one or more cellular core networks, one or more wireline networks, one or more wireless networks (e.g., one or more cellular networks, one or more wireless local area networks, one or more wireless metropolitan area networks, one or more wireless wide area networks, some combination thereof, or the like), or some combination thereof, and in some example embodiments can comprise the Internet. 
     In some embodiments, Device B  104  can be connected to network  110  via a wireless access network, such as a cellular network, wireless local area network (WLAN), wireless metropolitan area network, and/or other wireless access network. In embodiments in which Device B  104  is connected to the network  110  a cellular network, the cellular network can use any present or future developed cellular RAT supporting PS voice communication. For example, Device B  104  can be connected to a cellular network implementing an LTE technology, such as LTE, LTE-Advanced (LTE-A), and/or other present or future developed LTE RAT; various fifth generation (5G) RATs presently in development; and/or other present or future developed cellular RAT supporting PS voice communication. Additionally or alternatively, in some embodiments, Device B  104  can be connected to the network  110  via a wireline connection. 
     Device A  102  and Device B  104  can be engaged in an active voice call. The voice call can be initiated by either of Device A  102  or Device B  104 . In some example embodiments, both Device A  102  and Device B  104  can be engaged in the voice call via PS connections. Thus, for example, in some embodiments, both Device A  102  and Device B  104  can be engaged in a voice call supported by a VoIP connection, such as a VoLTE voice call. In instances in which both Device A  102  and Device B  104  are connected to a cellular network(s) implementing an LTE RAT, the voice call can be an end-to-end VoLTE call. 
     Device A  102  can be served by the first network  106  prior to undergoing an SRVCC handover. The first network  106  can be a network having a PS domain capable of supporting voice calls. As such, when Device A  102  is engaged in a voice call while on the first network  106 , the voice call can be serviced (e.g., as a VoLTE or other VoIP call) via a PS domain of the first network  106 . In some example embodiments, the first network  106  can be a network using an LTE technology, such as an LTE network, an LTE-Advanced (LTE-A) network, and/or other present or future developed LTE network. It will be appreciated, however, that first network  106  can be any network using a present or future developed RAT that can service voice calls via a PS domain, including, for example, various 5G cellular RATs presently in development. 
     Device A  102  can encounter conditions which can result in Device A  102  performing a handover to the legacy network  108  while the voice call is ongoing. For example, Device A  102  can exit a coverage area of the first network  106  due to device mobility, and can be redirected to the legacy network  108 . Handover of Device A  102  from the first network  106  to the legacy network  108  while engaged in an active voice call with Device B  104  can be facilitated via an SRVCC procedure to provide for continuity of the voice call on a CS domain of the legacy network  108 . 
     The legacy network  108  can be any network comprising a CS domain, which is configured to service voice calls as CS calls via the CS domain. By way of non-limiting example, the legacy network  108  can be a third generation (3G) network, such as a Wideband Code Division Multiple Access (WCDMA) network, a Time Division Synchronous Code Division Multiple Access (TD-SCDMA) network, or other Universal Mobile Telecommunications System (UMTS) network; a CDMA 2000 network or other network standardized by the Third Generation Partnership Project 2 (3GPP2) that supports voice calls via a CS domain; and/or other 3G network. As another example, the legacy network  108  can be a second generation (2G) network such as a Global System for Mobile Communications (GSM) network. 
     In accordance with some example embodiments as described further herein, Device A  102  can be configured to determine when there is a likelihood that it will perform an SRVCC handover from the first network  106  to the legacy network  108 . In this regard, Device A  102  can be configured to determine existence of a condition indicative of an impending SRVCC handover to the legacy network  108 . In an instance in which Device A  102  determines that there is a likelihood that it will perform an SRVCC handover (e.g., that there is a condition indicative of an impending SRVCC handover to the legacy network  108 ), Device A  102  can provide an advance indication to Device B  104  that Device A  102  is going to perform an SRVCC handover. Device B  104  can, in turn, receive the indication and, in accordance with some example embodiments, can modify a configuration parameter of its de-jitter buffer in advance of the SRVCC handover to improve audio continuity and provide a better user experience during an interruption in the transfer of voice packets that can occur during the SRVCC handover. 
       FIG. 2  illustrates a block diagram of an apparatus  200  that can be implemented on a communication device, such as Device A  102  and/or Device B  104 , in accordance with some example embodiments. In this regard, when implemented on a computing device, apparatus  200  can enable the computing device to operate within the system  100  in accordance with one or more example embodiments. It will be appreciated that the components, devices or elements illustrated in and described with respect to  FIG. 2  below may not be mandatory and thus some may be omitted in certain embodiments. Additionally, some embodiments can include further or different components, devices or elements beyond those illustrated in and described with respect to  FIG. 2 . 
     In some example embodiments, the apparatus  200  can include processing circuitry  210  that is configurable to perform actions in accordance with one or more example embodiments disclosed herein. In this regard, the processing circuitry  210  can be configured to perform and/or control performance of one or more functionalities of the apparatus  200  in accordance with various example embodiments, and thus can provide means for performing functionalities of the Device A  102  and/or Device B  104  in accordance with various example embodiments. The processing circuitry  210  can be configured to perform data processing, application execution and/or other processing and management services according to one or more example embodiments. 
     In some embodiments, the apparatus  200  or a portion(s) or component(s) thereof, such as the processing circuitry  210 , can include one or more chipsets, which can each include one or more chips. The processing circuitry  210  and/or one or more further components of the apparatus  200  can therefore, in some instances, be configured to implement an embodiment on a single chip or chipset. In some example embodiments in which one or more components of the apparatus  200  are embodied as a chipset, the chipset can be capable of enabling a computing device to operate in the system  100  when implemented on or otherwise operably coupled to the computing device. Thus, for example, one or more components of the apparatus  200  can provide a chipset, such as a cellular baseband chipset, configured to enable a computing device to operate over one or more cellular networks, such as the first network  106  and/or the legacy network  108 . 
     In some example embodiments, the processing circuitry  210  can include a processor  212  and, in some embodiments, such as that illustrated in  FIG. 2 , can further include memory  214 . The processing circuitry  210  can be in communication with or otherwise control transceiver(s)  216  and/or SRVCC adaptation module  218 . 
     The processor  212  can be embodied in a variety of forms. For example, the processor  212  can be embodied as various hardware-based processing means, such as a microprocessor, a coprocessor, a controller or various other computing or processing devices including integrated circuits such as, for example, an ASIC (application specific integrated circuit), an FPGA (field programmable gate array), some combination thereof, or the like. Although illustrated as a single processor, it will be appreciated that the processor  212  can comprise a plurality of processors. The plurality of processors can be in operative communication with each other and can be collectively configured to perform one or more functionalities of a wireless communication device as described herein. In some example embodiments, the processor  212  can be configured to execute instructions that can be stored in the memory  214  or that can be otherwise accessible to the processor  212 . As such, whether configured by hardware or by a combination of hardware and software, the processor  212  capable of performing operations according to various embodiments while configured accordingly. 
     In some example embodiments, the memory  214  can include one or more memory devices. Memory  214  can include fixed and/or removable memory devices. In some embodiments, the memory  214  can provide a non-transitory computer-readable storage medium that can store computer program instructions that can be executed by the processor  212 . In this regard, the memory  214  can be configured to store information, data, applications, instructions and/or the like for enabling the apparatus  200  to carry out various functions in accordance with one or more example embodiments. In some embodiments, the memory  214  can be in communication with one or more of the processor  212 , transceiver(s)  216 , or SRVCC adaptation module  218  via a bus(es) for passing information among components of the apparatus  200 . 
     The apparatus  200  can further include transceiver(s)  216 . The transceiver(s)  216  can enable the apparatus  200  to send wireless signals to and receive signals from one or more wireless networks, such as the first network  106  and the legacy network  108 . As such, the transceiver(s)  216  can be configured to support any type of RAT that may be implemented by the first network  106  and/or legacy network  108 . 
     The apparatus  200  can further include SRVCC adaptation module  218 . The SRVCC adaptation module  218  can be embodied as various means, such as circuitry, hardware, a computer program product comprising computer readable program instructions stored on a computer readable medium (for example, the memory  214 ) and executed by a processing device (for example, the processor  212 ), or some combination thereof. In some embodiments, the processor  212  (or the processing circuitry  210 ) can include, or otherwise control the SRVCC adaptation module  218 . 
     When implemented on a device, such as Device A  102 , performing an SRVCC handover, the SRVCC adaptation module  218  can be configured to determine a condition indicative of an impending SRVCC handover of Device A  102 , and can provide an indication to a remote device, such as Device B  104 , participating in a voice call. As such, the SRVCC adaptation module  218  can be configured to facilitate performance of operations illustrated in and described below with respect to  FIG. 3 . 
     When implemented on a device, such as Device B  104 , that is participating in a voice call with a remote device, such as Device A  102 , performing an SRVCC handover, the SRVCC adaptation module  218  can be configured to modify a configuration parameter of a de-jitter buffer in response to receiving an indication of the remote SRVCC handover in accordance with some example embodiments. As such, the SRVCC adaptation module  218  can be configured to facilitate performance of operations illustrated in and described below with respect to  FIG. 4 . 
       FIG. 3  illustrates a flowchart of an example method for providing an indication of an impending SRVCC handover in accordance with some example embodiments. In this regard,  FIG. 3  illustrates operations that can be performed by Device A  102  to inform Device B  104  of an impending SRVCC handover in accordance with some example embodiments. One or more of processing circuitry  210 , processor  212 , memory  214 , transceiver(s)  216 , or SRVCC adaptation module  218  can, for example, provide means for performing one or more of the operations illustrated in and described with respect to  FIG. 3 . 
     Operation  300  can include Device A  102  participating in a voice call with Device B via a connection between Device A  102  and the first network  106 . The voice call can be serviced on the Device A  102  end via a PS domain of the first network  106 . For example, the voice call can be serviced as a VoIP call by the first network  106 . In embodiments in which the first network  106  implements an LTE technology, the voice call can be serviced as a VoLTE call on the first network  106 . 
     Operation  310  can include Device A  102  determining a condition indicative of an impending SRVCC handover of Device A  102  from the first network  106  to the legacy network  108 . This determination can be made based at least in part on one or more measurements and/or other hints that can be available to Device A  102 . 
     As one example, the determination of operation  310  can be made based at least in part on a measurement of the first network  106 . For example, Device A  102  can determine that an observed signal quality (e.g., a downlink signal quality, such as a downlink signal power/strength) of the first network  106  is deteriorating and/or approaching a threshold for handover to another network. The observed signal quality can be expressed in terms of any measurement of signal quality that can be measured and/or otherwise derived by Device A  102 , and can vary depending on a type of RAT implemented by the first network  106 . By way of non-limiting example, the signal quality can comprise one or more of a reference signal received power (RSRP), reference signal received quality (RSRQ), received signal strength indicator (RSSI), channel quality indicator (CQI), signal-to-noise ratio (SNR), signal-to-interference plus noise ratio (SINR), and/or other signal quality measurement of the first network  106  that can be measured and/or otherwise derived by Device A  102 . 
     In some example embodiments in which the determination of operation  310  can be made based at least in part on a measurement of the first network  106 , Device A  102  can apply an advance SRVCC indication signal quality threshold that can be more conservative than a handover/reselection threshold such that Device A  102  can determine situations in which signal quality is deteriorating and approaching the handover/reselection threshold such that performance of an SRVCC handover is likely. Thus, for example, if the Device A  102  determines that the signal quality of the does not satisfy the advance SRVCC indication threshold, Device A  102  can determine that a condition indicative of an impending SRVCC handover exists. 
     The determination of operation  310  can additionally or alternatively be made based at least in part on an inter-RAT (iRAT) measurement of the legacy network  108 . For example, Device A  102  can determine that a measured signal quality (e.g., a measured signal power/strength) for the legacy network  108  satisfies an iRAT handover threshold. The measured signal quality of the legacy network  108  can be expressed in terms of any measurement of signal quality that can be measured and/or otherwise derived by Device A  102 , and can vary depending on a type of RAT implemented by the legacy network  108 . By way of non-limiting example, the signal quality can comprise one or more of a received signal code power (RSCP), received energy per chip of the pilot channel divided by the total received power spectral density (Ec/No), RSSI, SNR, SINR, and/or other signal quality measurement of the legacy network  108  that can be measured and/or otherwise derived by Device A  102 . 
     In some example embodiments, the determination of operation  310  can be made based at least in part on a combination of (e.g., a relationship between) a signal quality of the first network  106  and a signal quality of the legacy network  108 . For example, in some embodiments, the determination of operation  310  can be based at least in part on a Radio Resource Control (RRC) event related to a relationship between the signal quality of the first network  106  and the signal quality of the legacy network  108 , which can be indicative of an impending SRVCC handover. 
     The determination of operation  310  can additionally or alternatively be made based at least in part on a loading level on a serving base station, such as a serving evolved Node B (eNB), of the first network  106 . In this regard, in some instances, Device A  102  can determine that a degree of loading of the serving base station indicates that Device A  102  is likely to be redirected to the legacy network  108 . For example, in instances in which the loading level of the serving base station exceeds a threshold, Device A  102  can determine that an SRVCC handover to the legacy network  108  is likely. 
     As a further example, in some embodiments, the determination of operation  310  can be made in response to activation of Transmit Time Interval (TTI) bundling. In this regard, in some instances, the serving base station can activate TTI bundling on the uplink in response to deteriorating channel conditions, which can result in retransmissions of data on the uplink, such as in accordance with hybrid automatic repeat request (HARD) procedures. As such, activation of TTI bundling can be indicative that channel quality may continue to deteriorate and an SRVCC handover may be impending. 
     In some example embodiments, the determination of operation  310  can be made based at least in part on an error rate that can be observed by Device A  102  on the uplink and/or downlink. For example, if the Device A  102  determines that an error rate, such as a block error rate (BLER), frame error rate (FER), a HARQ retransmission count/frequency, and/or the like exceeds a threshold that can be indicative of declining channel quality approaching a handover threshold, Device A  102  can determine that an SRVCC handover is impending. 
     In response to the determination of operation  310 , Device A  102  can perform operation  320  and  330  to provide Device B  104  with advance notice of the anticipated SRVCC handover to enable Device B  104  to prepare for the interruption in transfer of voice packets that can occur during the SRVCC handover, as described further below with respect to  FIGS. 4 and 5 . 
     Operation  320  can comprise Device A  102  formatting a message comprising an indication that Device A  102  is going to perform an SRVCC handover. The message can be formatted in accordance with any signaling that can be sent to Device B  104 . 
     In some example embodiments, the message can be a dedicated signaling message that can be sent separately from voice packets for the voice call and which can be used to inform of an impending SRVCC handover. 
     Additionally or alternatively, in some example embodiments, the message can comprise a message that can be extended and/or repurposed to include a parameter indicating that Device A  102  is going to perform an SRVCC handover. For example, in some embodiments, an indication that Device A  102  is going to perform an SRVCC handover can be included in a voice packet comprising voice data for the voice call. In some such embodiments, the indication can be included in a header for the voice packet. For example, in embodiments in which voice data can be carried in real-time transport protocol (RTP) packets, the indication can be included in a payload header of an RTP packet, such as by way of non-limiting example, a reserved for future use field or the Codec Mode Request (CMR) field in an RTP payload header of an RTP packet that can be sent to Device B  104 . Accordingly, in such embodiments, the indication of impending SRVCC handover can be injected in a stream of voice packets communicated for the voice call. 
     Operation  330  can include Device A  102  sending the message to Device B  104  prior to performance of the SRVCC handover. Device B  104  can, in turn, receive the message, and, in response to the indication included in the message, can modify a configuration parameter its local de-jitter buffer to prepare for the interruption in voice packet transfer that can occur during the remote SRVCC handover, as described further below with respect to  FIG. 4 . 
       FIG. 4  illustrates a flowchart of another example method for preparing for a remote SRVCC handover in accordance with some example embodiments. In this regard,  FIG. 4  illustrates operations that can be performed by Device B  104  to prepare for remote SRVCC handover of Device A  102  in accordance with some example embodiments. One or more of processing circuitry  210 , processor  212 , memory  214 , transceiver(s)  216 , or SRVCC adaptation module  218  can, for example, provide means for performing one or more of the operations illustrated in and described with respect to  FIG. 4 . 
     Operation  400  can include Device B  104  participating in a voice call with Device A  102 . Operation  410  can include Device B  104  receiving an indication from Device A  102  that Device A  102  is going to perform an SRVCC handover. The indication received in operation  410  can, for example, be included in a message that can be formatted and sent by Device A  102  as described above with respect to operations  320  and  330 . 
     Operation  420  can include Device B  104  modifying a configuration parameter of a de-jitter buffer (e.g., adjusting the de-jitter buffer) containing one or more buffered voice packets received from Device A  102  in advance of the remote SRVCC handover in response to the indication received in operation  410 . In this regard, operation  420  can include modifying one or more de-jitter buffer configuration parameters to facilitate audio continuity during an interruption in the transfer of voice packets that can occur during the SRVCC handover. 
     For example, in some embodiments, operation  420  can comprise increasing a size of the de-jitter buffer so that additional voice packets are queued in advance of the SRVCC handover. In this regard, emptying of the de-jitter buffer during interruption of the transfer of voice packets that can occur during the SRVCC procedure can be avoided to avoid the audio discontinuity that could occur if the de-jitter buffer were emptied during the SRVCC handover. 
     Additionally or alternatively, in some embodiments, operation  420  can comprise Device B  104  modifying an amount of time warping applied to one or more voice packets queued in the de-jitter buffer. In this regard, audio samples collected prior to the remote SRVCC handover can be time warped to improve user perception of the gap in reception of packets that can occur during the SRVCC procedure. For example, a delay between provision of audio samples from the de-jitter buffer can be at least temporarily increased to avoid occurrence of a gap that can be noticeable by a user. 
       FIG. 5  illustrates a signaling diagram in accordance with some example embodiments. In this regard,  FIG. 5  illustrates signaling that can be exchanged and operations that can be performed within a system comprising Device A  502 , first network  504 , legacy network  506 , access network  508 , and Device B  510  in accordance with some example embodiments. Device A  502  and Device B  510  can, for example, comprise embodiments of Device A  102  and Device B  104 , respectively. The first network  504  and legacy network  506  can, for example, correspond to embodiments of the first network  106  and legacy network  108 , respectively. The access network  508  can comprise any access network (e.g., wireless or wireline) that can be used by Device B  510  to gain network access and engage in communication with Device A  502 . Communication between the access network  508  and the cellular access networks (e.g., first network  504  and legacy network  506 ) that can be used by Device A  502  can be facilitated by one or more cellular core networks, one or more wireless networks, one or more wireline networks, or some combination thereof. In some example embodiments, the network  110  can enable communication between the access network  508  and cellular access networks that can be used by Device A  502 . One or more of processing circuitry  210 , processor  212 , memory  214 , transceiver(s)  216 , or SRVCC adaptation module  218  can, for example, provide means for performing one or more of the operations attributed to Device A  502  and/or to Device B  510 . 
     As illustrated in operation  520 , Device A  502  and Device B  510  can have an ongoing voice call. The voice call can be serviced via the first network  504  as a PS voice call, such as a VoLTE call or other VoIP call. 
     Operation  530  can include Device A  502  determining a condition indicative of an impending SRVCC handover. In this regard, operation  530  can correspond to an embodiment of operation  310 . 
     In response to the condition indicative of the impending SRVCC handover, Device A  502  can format and send a message indicating that Device A  502  is going to perform an SRVCC handover to Device B  540 . The message that can be formatted and sent attendant to performance of operation  540  can, for example, comprise a message that can be formatted and sent in accordance with performance of operations  320 - 330 , as described above. 
     Device B  510  can receive the message indicating that Device A  502  is going to perform an SRVCC handover and, in response, can prepare for the SRVCC handover by modifying a configuration parameter of its de-jitter buffer, as illustrated in operation  550 . Operation  550  can, for example, correspond to an embodiment of operation  420 , as described above. 
     Operation  560  can include Device A  502  and first network  504  exchanging handover initiation signaling. The handover initiation signaling can, for example, include a measurement report that can be sent by Device A  502  and/or a redirection message that can be sent by first network  504 . The first network  504  can coordinate handover of the voice call to the legacy network  506 , such as with the assistance of one or more core network elements that can be used to interface the first network  504  and legacy network  506 . Attendant to performance of the SRVCC handover, Device A  502  can establish a connection with the legacy network  506  and can complete the SRVCC handover, at operation  570 . 
     After completion of the SRVCC handover, the voice call between Device A  502  and Device B  510  can continue via the legacy network  506 , as illustrated by operation  580 . The voice call can be serviced as a CS voice call via a CS domain of the legacy network  506  after the SRVCC handover. 
     The various aspects, embodiments, implementations or features of the described embodiments can be used separately or in any combination. Various aspects of the described embodiments can be implemented by software, hardware or a combination of hardware and software. The described embodiments can also be embodied as a computer readable medium (or mediums) storing computer readable code including instructions that can be performed by one or more computing devices. The computer readable medium may be associated with any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer readable medium include read-only memory, random-access memory, CD-ROMs, HDDs, DVDs, magnetic tape, and optical data storage devices. The computer readable medium can also be distributed over network-coupled computer systems so that the computer readable code may be stored and executed in a distributed fashion. 
     In the foregoing detailed description, reference was made to the accompanying drawings, which form a part of the description and in which are shown, by way of illustration, specific embodiments in accordance with the described embodiments. Although these embodiments are described in sufficient detail to enable one skilled in the art to practice the described embodiments, it is understood that these examples are not limiting; such that other embodiments may be used, and changes may be made without departing from the spirit and scope of the described embodiments. For example, it will be appreciated that the ordering of operations illustrated in the flowcharts is non-limiting, such that the ordering of two or more operations illustrated in and described with respect to a flowchart can be changed in accordance with some example embodiments. As another example, it will be appreciated that in some embodiments, one or more operations illustrated in and described with respect to a flowchart can be optional, and can be omitted. 
     Further, the foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of specific embodiments are presented for purposes of illustration and description. The description of and examples disclosed with respect to the embodiments presented in the foregoing description are provided solely to add context and aid in the understanding of the described embodiments. The description is not intended to be exhaustive or to limit the described embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications, alternative applications, and variations are possible in view of the above teachings. In this regard, one of ordinary skill in the art will readily appreciate that the described embodiments may be practiced without some or all of these specific details. Further, in some instances, well known process steps have not been described in detail in order to avoid unnecessarily obscuring the described embodiments.

Metadata:
Filing Date: 20140130
Publication Date: 20161220
Grant Date: 20161220
Priority Date: 20130204
Inventors: KHAY-IBBAT SAMY
VANGALA SARMA V.
VALLATH SREEVALSAN
DAMJI NAVID
VERGER LUCIANO MIGUEL
VASUDEVAN SRINIVASAN
MAKHARIA SHIVESH
KODALI SREE RAM
CHAUDHARY MADHUSUDAN
SHI JIANXIONG
Assignee: APPLE INC
CPC Classifications: [{"code": "H04L65/102", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04J3/0632", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W36/0066", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L29/06176", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L1/205", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L29/06027", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W36/0022", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W76/041", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W36/00224", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W76/22", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L1/205", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L65/102", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L65/1101", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W76/22", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L65/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04J3/0632", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W36/0066", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W36/00224", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 51259165