PATENT DOCUMENT

Publication Number: US-10999330-B2
Application Number: US-201816349587-A
Country: US
Kind Code: B2

Title: Management of voice services for user equipments in coverage enhancement (CE) mode B

Abstract:
Embodiments of the present disclosure describe methods, apparatuses, and systems for management of voice services for user equipments (UEs) in coverage enhancement (CE) mode B. A cellular protocol stack (CPS) of the UE may indicate to an internet protocol (IP) multimedia services (IMS) circuitry of the UE that the UE is operating in the CE mode B (or will be operating in the CE mode B when it awakes from idle mode). The IMS circuitry may receive an SIP invite from an IMS server to invite the UE to engage in a mobile terminated (MT) call. In response to the SIP invite, the IMS circuitry of the UE may reject the SIP invite and deregister the UE from voice services. Other embodiments may be described and claimed.

Claims:
What is claimed is: 
     
       1. One or more non-transitory computer-readable media having instructions, stored thereon, that when executed by one or more processors, are to cause a user equipment (UE) to:
 determine that the UE is to transition to a coverage enhancement (CE) mode B based on radio conditions on a wireless communication network; 
 transition the UE to the CE mode B based on the determination; 
 process a session initiation protocol (SIP) invite received from an internet protocol (IP) multimedia services (IMS) server, the SIP invite to request initiation of a voice call; and 
 reject the SIP invite and deregister the UE from voice services on the wireless communication network in response to the SIP invite and based on operation of the UE in the CE mode B. 
 
     
     
       2. The one or more non-transitory media of  claim 1 , wherein, to deregister the UE from voice services, the instructions, when executed, are to cause the UE to transmit an SIP register message to the IMS server. 
     
     
       3. The one or more non-transitory media of  claim 2 , wherein, to reject the SIP invite, the instructions are to cause the UE to transmit a message to the IMS server to indicate that the UE is temporarily unavailable. 
     
     
       4. The one or more non-transitory media of  claim 1 , wherein, to reject the SIP invite and deregister the UE from voice services, the instructions, when executed, are to cause the UE to transmit a single message to the IMS server to indicate to the IMS server that the SIP invite is rejected and request deregistration of the UE from voice services. 
     
     
       5. The one or more non-transitory media of  claim 1 , wherein the instructions, when executed, are further to cause the UE to:
 determine that the UE is to transition to a CE mode A or a normal coverage mode based on updated radio conditions on the wireless communication network; 
 transition the UE to the CE mode A or the normal coverage mode; and 
 re-register for voice services on the wireless communication network based on the transition to the CE mode A or the normal coverage mode. 
 
     
     
       6. The one or more non-transitory media of  claim 1 , wherein the instructions, when executed, are further to cause the UE to reject a mobile originated (MO) call request to initiate a voice call when the UE is in the CE mode B. 
     
     
       7. The one or more non-transitory media of  claim 1 , wherein the determination and transition are performed when the UE is configured as a data centric UE, and wherein the UE is not to use the CE mode B when the UE is configured as a voice centric UE. 
     
     
       8. The one or more non-transitory media of  claim 1 , wherein the instructions, when executed, are further to cause the UE to display an indicator to indicate to a user of the UE that voice services are unavailable based on the determination that the UE is to transition to the CE mode B. 
     
     
       9. The one or more non-transitory computer-readable media of  claim 1 , wherein, to determine that the UE is to transition to the CE mode B based on radio conditions on the wireless communication network, the instructions are to cause the UE to:
 perform signal measurements for radio conditions on the wireless communication network, the signal measurements corresponding to one or more of a channel quality indicator, CQI, a received signal received power, RSRP, a received signal received quality, RSRQ, a received signal strength indicator, RSSI, a signal-to-noise ratio, SNR, or a signal-to-noise-plus-interference ratio, SINR; and 
 determine that the UE is to transition to the CE mode B based at least on one or more thresholds corresponding to the signal measurements. 
 
     
     
       10. One or more non-transitory computer-readable media having instructions, stored thereon, that when executed by one or more processors, are to cause a internet protocol (IP) multimedia services (IMS) server to:
 transmit a session initiation protocol (SIP) invite to a first user equipment (UE); 
 obtain, from the first UE responsive to the SIP invite, a request to deregister the first UE from voice services on a wireless communication network; 
 obtain a mobile terminated (MT) call trigger from a second UE to initiate an MT call with the first UE; and 
 reject the MT call trigger based on the request to deregister the first UE from voice services. 
 
     
     
       11. The one or more non-transitory media of  claim 10 , wherein the request to deregister is an SIP register message. 
     
     
       12. The one or more non-transitory media of  claim 11 , wherein the instructions, when executed, are further to cause the IMS server to obtain a message from the first UE to indicate that the first UE is temporarily unavailable. 
     
     
       13. The one or more non-transitory media of  claim 10 , wherein the request to deregister the first UE from voice services is included in a message that also indicates that the SIP invite is rejected. 
     
     
       14. The one or more non-transitory media of  claim 10 , wherein the instructions, when executed, are further to cause the IMS server to obtain an SIP register message from the first UE to re-register the first UE for voice services. 
     
     
       15. An apparatus to be employed by a user equipment (UE), the apparatus comprising:
 circuitry to implement a cellular protocol stack to determine that radio conditions on a wireless communication network are below a quality level; and 
 internet protocol (IP) multimedia services (IMS) circuitry coupled to the cellular protocol stack, the IMS circuitry to:
 receive an indication from the cellular protocol stack that the radio conditions are below the quality level; 
 receive a session initiation protocol (SIP) invite from an IMS server to request initiation of a voice call; and 
 reject the SIP invite and deregister from voice services on the wireless communication network in response to the SIP invite and based on the indication that the radio conditions are below the quality level. 
 
 
     
     
       16. The apparatus of  claim 15 , wherein the IMS circuitry is to transition the UE to a coverage enhancement (CE) mode B based on the indication that the radio conditions are below the quality level. 
     
     
       17. The apparatus of  claim 16 , wherein the IMS circuitry is to reject the SIP invite and deregister from voice services when the UE is configured as a data centric UE, and wherein the UE is not to use the CE mode B when the UE is configured as a voice centric UE. 
     
     
       18. The apparatus of  claim 15 , wherein:
 to reject the SIP invite, the IMS circuitry is to transmit a message to the IMS server to indicate that the UE is temporarily unavailable; and 
 to deregister the UE from voice services, the IMS circuitry is to transmit an SIP register message to the IMS server. 
 
     
     
       19. The apparatus of  claim 15 , wherein, to reject the SIP invite and deregister the UE from voice services, the IMS circuitry is to transmit a single message to the IMS server to indicate to the IMS server that the SIP invite is rejected and request deregistration of the UE from voice services. 
     
     
       20. The apparatus of  claim 15 , wherein the circuitry to implement the cellular protocol stack is to determine that the radio conditions on the wireless communication network are above a quality level; and
 wherein the IMS circuitry is to:
 receive an indication from the circuitry to implement the cellular protocol stack that the radio conditions are above the quality level; and 
 transmit an SIP register message to the IMS server to re-register for voice services on the wireless communication network based on the indication that the radio conditions are above the quality level. 
 
 
     
     
       21. The apparatus of  claim 15 , wherein the IMS circuitry is further to:
 receive, from the circuitry to implement the cellular protocol stack, a mobile originated (MO) call request to request initiation of a voice call; and 
 reject the MO call request based on the indication that the radio conditions are below the quality level. 
 
     
     
       22. The apparatus of  claim 15 , wherein the IMS circuitry is further to cause the UE to display an indicator to indicate to a user of the UE that voice services are unavailable based on the indication that the radio conditions are below the quality level. 
     
     
       23. The apparatus of  claim 15 , wherein the radio conditions include one or more of a channel quality indicator (CQI), a received signal received power, a received signal received quality, a received signal strength indicator, a signal-to-noise ratio, or a signal-to-noise-plus-interference ratio, and wherein the quality level corresponds to one or more thresholds. 
     
     
       24. A processor included in a user equipment (UE) for a cellular communication network, the processor comprising:
 first circuitry to execute one or more instructions that cause the processor to perform operations comprising determining that radio conditions in the cellular communication network is below a quality level; and 
 second circuitry to execute one or more instructions that cause the processor to perform operations comprising:
 transitioning the UE to a coverage enhancement (CE) mode B based on the determination about the radio conditions; 
 processing a session initiation protocol (SIP) invite received from an internet protocol (IP) multimedia services (IMS) server, the SIP invite to request initiation of a voice call; and 
 rejecting the SIP invite and deregister the UE from voice services on the cellular communication network in response to the SIP invite and based on operation of the UE in the CE mode B. 
 
 
     
     
       25. The processor of  claim 24 , wherein, to deregister the UE from voice services, the operations comprise at least one of:
 transmitting a SIP register message to the IMS server, or 
 transmitting a message to the IMS server to indicate that the UE is temporarily unavailable. 
 
     
     
       26. The processor of  claim 24 , wherein the operations further comprise:
 determining that the UE is to transition to a CE mode A or a normal coverage mode based on updated radio conditions on the cellular communication network; 
 transitioning the UE to the CE mode A or the normal coverage mode; and 
 re-registering for voice services on the cellular communication network based transitioning to the CE mode A or the normal coverage mode. 
 
     
     
       27. The processor of  claim 24 , wherein the determination and transition are performed when the UE is configured as a data centric UE, and wherein the UE is not to use the CE mode B when the UE is configured as a voice centric UE.

Description:
RELATED APPLICATION 
     This application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/US2018/016285, filed Jan. 31, 2018, entitled “MANAGEMENT OF VOICE SERVICES FOR USER EQUIPMENTS IN COVERAGE ENHANCEMENT (CE) MODE B,” which claims priority to U.S. Provisional Application No. 62/457,598, filed Feb. 10, 2017, the entire disclosures of which are hereby incorporated by reference. 
    
    
     FIELD 
     Embodiments of the present disclosure generally relate to the field of wireless communication networks, and more particularly, to apparatuses, systems, and methods associated with management of voice services for user equipments (UEs) in coverage enhancement (CE) mode B. 
     BACKGROUND 
     A user equipment (UE) may be able to operate in a variety of coverage modes, such as a normal coverage mode, a coverage enhancement (CE) mode A, and/or a CE mode B. The UE may determine whether to operate in normal coverage or CE, e.g., based on radio conditions on the wireless communication network. In idle mode, the UE doesn&#39;t inform the network about which coverage mode it is operating in. While operating in CE, when the UE wants to establish a connection with an access node (e.g., evolved Node B (eNB) or next generation base station (gNB)) of the wireless communication network, the access node configures the UE for either CE mode A or CE mode B. For example, the UE may operate in CE mode A in poor radio conditions, and may operate in CE mode B in even poorer radio conditions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, like reference numerals designate like structural elements. Embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings. 
         FIG. 1  schematically illustrates a network environment in accordance with some embodiments. 
         FIG. 2  schematically illustrates an electronic device in accordance with some embodiments. 
         FIG. 3  schematically illustrates an internet protocol (IP) multimedia services (IMS) server in accordance with some embodiments. 
         FIG. 4  graphically illustrates signaling that may be performed by a UE and an IMS server over time, in accordance with some embodiments. 
         FIG. 5  is a flowchart of a process for managing voice services when the UE is in the CE mode B, according to some embodiments. 
         FIG. 6  is another flowchart of a process for managing voice services when the UE is in the CE mode A, according to some embodiments. 
         FIG. 7  illustrates baseband circuitry in accordance with some embodiments. 
         FIG. 8  illustrates communication circuitry in accordance with some embodiments. 
         FIG. 9  illustrates a cellular protocol stack in accordance with some embodiments. 
         FIG. 10  illustrates protocol entities that may be implemented in wireless communication devices, in accordance with some embodiments. 
         FIG. 11  illustrates hardware resources in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings, which form a part hereof wherein like numerals designate like parts throughout, and in which is shown by way of illustration embodiments that may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. 
     Various operations may be described as multiple discrete actions or operations in turn, in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations may not be performed in the order of presentation. Operations described may be performed in a different order than the described embodiment. Various additional operations may be performed or described operations may be omitted in additional embodiments. 
     For the purposes of the present disclosure, the phrases “A or B,” “A and/or B,” and “A/B” mean (A), (B), or (A and B). 
     The description may use the phrases “in an embodiment,” or “in embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments of the present disclosure, are synonymous. 
     As used herein, the term “circuitry” may refer to, be part of, or include any combination of integrated circuits (for example, a field-programmable gate array (“FPGA”) an application specific integrated circuit (“ASIC”), etc.), discrete circuits, combinational logic circuits, system on a chip, SOC, system in a package, SiP, that provides the described functionality. In some embodiments, the circuitry may execute one or more software or firmware modules to provide the described functions. In some embodiments, circuitry may include logic, at least partially operable in hardware. 
       FIG. 1  illustrates a network environment  100  in accordance with various embodiments. Network environment  100  may include a plurality of user equipments (UEs), including UE  104  and UE  108 . Network environment  100  may further include an internet protocol (IP) multimedia services (IMS) server  112 . The IMS server  200  may facilitate IMS voice and/or video calls between two (or more) UEs, such as between the UE  104  and the UE  108 . From one UE&#39;s perspective, the IMS calls may be either mobile originated (MO) or mobile terminated (MT). MO calls are initiated by that UE, while MT calls are initiated by another UE. The IMS server  112  may receive a request (also referred to as an MT call trigger) from the originating UE that initiates the IMS call. The request may identify the terminating UE with which the originating UE wishes to connect. The IMS server  200  may send a session initiation protocol (SIP) invite to the terminating UE to invite the terminating UE to form an IMS call with the originating UE. 
     In various embodiments, communications between the IMS server  112  and the UE  104  or UE  108  may be routed between respective access nodes  116  or  120  of a radio access network (“RAN”). In some embodiments, the communications between the IMS server  112  and the UE  104  or UE  108  may be further routed between one or more additional devices (not shown), such as a mobility management entity (MME), packet data network gateway (P-GW) and/or serving gateway (S-GW). The access nodes  116  and/or  120  may be referred to as a base station (“BS”), NodeB, evolved NodeB (“eNB”), next Generation NodeB (“gNB”), RAN node, Road Side Unit (“RSU”), and so forth, and can comprise a ground station (e.g., a terrestrial access point) or a satellite station providing coverage within a geographic area (e.g., a cell). An RSU may refer to any transportation infrastructure entity implemented in or by an gNB/eNB/RAN node or a stationary (or relatively stationary) UE, where an RSU implemented in or by a UE may be referred to as a “UE-type RSU”, an RSU implemented in or by an eNB may be referred to as an “eNB-type RSU.” 
     In some embodiments, the RAN may be a next generation (“NG”) radio access network (“RAN”), in which case the access node  116  and/or access node  120  may be a gNB that communicates with the respective UE  104  or  108  using a new radio (“NR”) access technology. 
     The UE  104  and/or UE  108  may be any mobile or non-mobile computing device that is connectable to one or more cellular networks. For example, the UE  104  and/or  108  may be a smartphone, a laptop computer, a desktop computer, a vehicular computer, a smart sensor, etc. In some embodiments, the UE  104  and/or  108  may be an Internet of Things (“IoT”) UE, which may include a network access layer designed for low-power IoT applications utilizing short-lived UE connections. An IoT UE can utilize technologies such as machine-to-machine (“M2M”) or machine-type communications (“MTC”) for exchanging data with an MTC server or device via a public land mobile network (“PLMN”), Proximity-Based Service (“ProSe”) or device-to-device (“D2D”) communication, sensor networks, or IoT networks. The M2M or MTC exchange of data may be a machine-initiated exchange of data. An IoT network describes interconnecting IoT UEs, which may include uniquely identifiable embedded computing devices (within the Internet infrastructure), with short-lived connections. The IoT UEs may execute background applications (for example, keep-alive messages, status updates, etc.) to facilitate the connections of the IoT network. 
       FIG. 2  schematically illustrates an electronic device  200  that may correspond to a UE (e.g., the UE  104  and/or UE  108 ) or another device described herein (e.g., IMS server  112 , access node  116 , and/or access node  120 ) in accordance with various embodiments. As shown, the electronic device  200  may include application circuitry  202 , baseband circuitry  204 , radio frequency circuitry  206 , front-end module (FEM) circuitry  208 , and one or more antennas  210 , coupled together at least as shown. In embodiments in which the electronic device  200  corresponds to a UE (e.g., UE  104  and/or UE  108 ), the UE may include a cellular protocol stack (CPS)  212  and an IMS circuitry  214  coupled to one another. In some embodiments, the CPS  212  may be at least partially implemented in the baseband circuitry  204 , such as by CPU  804   e  and/or one or more of baseband processors  204   a - d . In some embodiments, the IMS circuitry  214  may be at least partially implemented in the application circuitry  202 , such as by processor(s)  802   a  and/or computer-readable media  802   b . These and other components of the electronic device  200  will be described in further detail below. 
       FIG. 3  schematically illustrates an IMS server  300  in accordance with various embodiments. The IMS server  300  may correspond to the IMS server  112 . In various embodiments, the IMS server  300  may include transceiver circuitry  304 , processing circuitry  308 , and/or a memory  312  coupled to one another as shown. In some embodiments, the memory  312  may store instructions that are executable by the processing circuitry  308  to perform various operations as described herein. 
     Various embodiments may be described herein from the perspective of the UE  104  receiving an MT call from the UE  108  and/or initiating an MO call to the UE  108 . However, it will be apparent that the description may also be applied to the perspective of the UE  108  initiating an MO call to the UE  104  and/or receiving an MT call from the UE  104   
     In various embodiments, the UE  104  may be able to operate in a variety of coverage modes, such as a normal coverage mode, a coverage enhancement (CE) mode A, and/or a CE mode B. The UE  104  (e.g., the CPS  212  of the UE  100 ) may determine which coverage mode to operate in based on radio conditions on the wireless communication network. For example, if radio conditions are below a first quality level, the UE  104  may operate in the CE mode B. If radio conditions are above the first quality level but below a second quality level then the UE  104  may operate in the CE mode A. If radio conditions are above the second quality level, then the UE  104  operate in the normal coverage mode. 
     In various embodiments, communications between the UE  104  and the access node  116  may be repeated when the UE  104  is in the CE mode A and/or CE mode B. For example, the access node  116  may repeat transmissions to the UE  104 , such as a physical downlink control channel (PDCCH) and/or physical downlink shared channel (PDSCH). Additionally, or alternatively, UE  104  may repeat transmissions to the access node  116  (such as a physical uplink control channel (PUCCH) and/or physical uplink shared channel (PUSCH)) A greater number of repetitions of the communications may be used when the UE  104  is in the CE mode B than when the UE is in the CE mode A, thereby enabling coverage in lower quality conditions. The non-access stratum (NAS) timers in the UE  104  and MME may be extended to cover the expected delay for signaling and thereby avoid NAS message retransmission increase and higher signaling load. Furthermore, in some embodiments, one or more additional functions may be disabled when the UE  104  is in the CE mode B rather than the CE mode A, or in the CE mode A rather than the normal coverage mode. 
     In various embodiments, one or more protocol layers of the CPS  212  of the UE  104  may determine the radio conditions based on one or more signal measurements. For example, in some embodiments, the radio conditions may correspond to one or more of a channel quality indicator (CQI), a received signal received power (RSRP), a received signal received quality (RSRQ), a received signal strength indicator (RSSI), a signal-to-noise ratio (SNR), or a signal-to-noise-plus-interference ratio (SINR). The quality level that determines which mode the coverage mode the UE  104  will operate in may correspond to one or more thresholds associated with the radio conditions. 
     When the UE  104  is in the CE mode B, the UE  104  should not participate in IMS voice or video calls. Accordingly, in accordance with various embodiments described herein, the UE  104  may deregister from voice and/or video services with the wireless communication network responsive to an invitation (e.g., SIP invite) from the IMS server  112  for a MT call when the UE  104  is in the CE mode B. 
     For example, the CPS  212  of the UE  104  (e.g., the radio resource control (RRC) layer of the CPS  212 ) may determine that radio conditions on the wireless communication network (e.g., on the serving cell) are below the first quality level, and may send an indication to the IMS circuitry  214  to indicate that the radio conditions are below the first quality level. The indication may also indicate that the UE  100  is to transition to the CE mode B. In some embodiments, the CPS  104  may transition the UE  100  to the CE mode B in response to the determination. In other embodiments, the CPS  104  may be in a radio resource control (RRC) connection state (e.g., RRC-Idle state) that does not involve being in a specific coverage mode. However, the CPS  104  may transition the UE  100  to the CE mode B when the UE  100  transitions to a different RRC connection state that does require being in a specific coverage mode, such as RRC-Connected. 
     In various embodiments, the IMS circuitry  214  of the UE  104  may receive an SIP invite from the IMS server  112 . The SIP invite may request initiation of a MT IMS voice or video call, such as voice over Long Term Evolution (voLTE). In some embodiments, the CPS  212  may transition the UE  104  to the RRC-Connected mode as part of receiving the SIP invite, and thus the CPS  212  may transition the UE  104  to the CE mode B. The IMS circuitry  214  may reject the SIP invite and deregister from voice and/or video services on the wireless communication network in response to the SIP invite and based on the indication that the radio conditions are below the first quality level (and/or based on the UE  104  being in the CE mode B). 
     The IMS circuitry  214  may deregister from voice and/or video services, for example, by transmitting an SIP register message to the IMS server  112 . The SIP register message may be similar to the SIP register message that is transmitted by the UE  104  to initially register for voice and/or video services, but with a field having a different value to indicate that the UE  104  is requesting deregistration from the voice and/or video services. In some such embodiments, the IMS circuitry  214  may also transmit another message (e.g., a  480  temporary unavailable message) to the IMS server  112  to reject the SIP invite. Alternatively, a new message may be transmitted by the IMS circuitry  214  to the IMS server  112  to deregister the UE  104  from voice and/or video services. For example, the IMS circuitry  214  may transmit a single message to the IMS server  112  to both reject the SIP invite and deregister the UE  104  from voice and/or video services. The new message may additionally or alternatively omit one or more fields that are included in the SIP register message but not necessary for the purpose of deregistration. 
     In various embodiments, the IMS server  112  may process the deregistration of the UE  104  from the voice or video services, and may mark the UE  104  as temporarily unavailable. For example, referring to IMS server  300  of  FIG. 3 , the processor circuitry  308  of the IMS server  300  may receive (e.g., via the transceiver circuitry  304 ) a message from the UE  104  to request the deregistration, and may store a status indicator in the memory  312  to indicate that the UE  104  is temporarily unavailable. The processing circuitry  308  of the IMS server  300  may reject any further requests for an IMS voice or video call with the UE  104  received by the IMS server  200  (e.g., from the UE  108 ) while the UE  104  is marked as temporarily unavailable. Accordingly, the IMS server  300  may not send an SIP invite to the UE  104  or configure dedicated evolved packet system (EPS) bearers for the UE  104  while the UE  104  is in the CE mode B, thereby conserving signaling and resources. 
     As discussed above, the UE  104  may not deregister from voice and/or video services responsive to the indication that the radio conditions are below the first quality level, but may instead only deregister from voice and/or video services after also receiving an SIP invite. This prevents unnecessary signaling when the UE  104  transitions to CE mode B. 
     In various embodiments, the UE  104  (e.g., the CPS  212 ) may determine that signal conditions on the wireless communication network are sufficient (e.g., above a signal quality level) for voice and/or video calls. The CPS  212  may send an indication to the IMS circuitry  214  of the UE  104  to indicate that the signal conditions are sufficient for voice and/or video calls. The IMS circuitry  214  may re-register for voice and/or video services in response to the indication. For example, the IMS circuitry  214  may send an SIP register message to the IMS server  112 . After re-registration, the UE  104  may again be available for MT IMS calls. 
     In some embodiments, the signal conditions sufficient for the UE  104  to again engage in voice and/or video calls may correspond to signal conditions that are suitable for the UE  104  to transition from the CE mode B to the CE mode A. However, when the UE  104  is in idle mode, the UE  104  may not know if it operates in CE mode A or CE mode B until it enters the RRC connected mode with the access node  116 . Accordingly, the signal quality level used by the UE  104  to determine whether to re-register for voice services may be the same or different than the parameters used by the access node  116  to determine whether the UE  104  is to operate in the CE mode A or CE mode B. 
     In various embodiments, a user of the UE  104  may initiate an MO call while the UE  104  is in the CE mode B. For example, the IMS circuitry  214  may receive an MO call request initiated by the user. The IMS circuitry  214  may reject the MO call request. Accordingly, the UE  104  may not transmit a request to the IMS server  112  to initiate an MO IMS call when the UE  104  is in the CE mode B. 
     In some embodiments, the UE  104  may display an indicator on a display of the UE  104  when the UE  104  is in the CE mode B. The indicator may indicate (e.g., to the user) that voice and/or video services are unavailable on the UE  104 . 
     In some embodiments, the UE  104  may be configured as a “data centric” UE or a “voice centric” UE. The UE  104  may be permitted to operate in the CE mode B when the UE is configured as a data centric UE, but may not be permitted to operate in the CE mode B when the UE is configured as voice centric. Accordingly, the UE  104  may perform the operations described herein related to operation in the CE mode B (e.g., determination that the signal conditions are below the signal quality level and deregistration from voice and/or video services) when the UE  104  is configured as a data centric UE, but not when the UE  104  is configured as a voice centric UE. In some embodiments, the configuration of the UE  104  as data centric or voice centric may be selected/changed by the user. Additionally, or alternatively, the configuration may be set by another entity, such as the device manufacturer or the network operator, for example, based on the type of device that the UE  104  is. In some such embodiments, the user may not be permitted to change the configuration. 
     In some embodiments, similar features may be used by the UE  104  to deregister from one or more services when the UE  104  is operating in the CE mode A. For example, the UE  104  may deregister from video services (but not voice services) when the UE  104  is in the CE mode A. In some embodiments, the UE  104  may deregister from the video services responsive to receiving an SIP invite for a video call. The UE  104  may deregister from both video and voice services when the UE  104  is in the CE mode B, as discussed herein. 
       FIG. 4  graphically illustrates signaling that may be performed by a UE  404  (e.g., UE  104 ) and an IMS server  408  (e.g., IMS server  112 ) over time, in accordance with some embodiments. The UE  404  may initially be in the normal coverage (NC) or CE mode A. Accordingly, the IMS server  408  may have the UE  404  marked as available for voice services. The IMS server  408  may receive an MT call trigger  412  (e.g., from another UE, such as the UE  108 ) to request an IMS call with the UE  404 . The IMS server  408  may send an SIP invite  416  to the UE  404 , and configure dedicated EPS bearers for the UE  404 . The voice call may be completed at  420 . 
     At time point  424 , the UE  404  may transition to the CE mode B. However, the UE  404  may not inform the IMS server  408  of the transition at that time. Thereafter, the IMS server  408  may receive another MT call trigger  428  and send another SIP invite  432  to the UE  404 . At  436 , the UE  404  may reject the SIP invite  432  and deregister from voice services responsive to receiving the SIP invite  432  and based on the UE  404  being in the CE mode B. The IMS server  408  may mark the UE  404  as temporarily unavailable for voice services. 
     The IMS server  408  may receive one or more further MT call triggers  440   a - c . However, the IMS server  408  may reject the further MT call triggers  440   a - c  (e.g., by sending respective rejection messages  444   a - c  to the requesting UE). Accordingly, the IMS server  408  may not send an SIP invite to the UE  404  and/or configure dedicated EPS bearers for the UE  404  while the UE  404  is marked as temporarily unavailable. 
     At time point  448 , the UE  404  may transition to the CE mode A or normal coverage mode. The UE  404  may send a message  452  (e.g., SIP register message) to the IMS server  408  to re-register for voice services responsive to the transition to the CE mode A or normal coverage mode. The IMS server  408  may mark the UE  404  as available for voice services (or remove/delete the prior indication that the UE  404  was unavailable for voice services). 
     The IMS server  408  may thereafter receive another MT call trigger  456  to request an IMS call with the UE  404 . The IMS server  408  may send an SIP invite  460  to the UE  404  and the call may be completed at  464 . 
       FIG. 5  illustrates a signal flowchart of a process  500 , and depicts various signals that may be communicated between a CPS  504 , an IMS circuitry  508 , and an IMS server  512  during the process  500 . The CPS  504  and IMS circuitry  508  may be included in a UE (e.g., UE  104 ), and may correspond to the CPS  212  and IMS circuitry  214  of  FIG. 2 . The IMS server  512  may correspond to the IMS server  112  of  FIG. 1  and/or IMS server  300  of  FIG. 3 . The process  500  depicted in  FIG. 5  may use the existing SIP register message to deregister the UE from voice services in response to receiving an SIP invite when the UE is in the CE mode B. 
     The CPS  504  may send an indication  516  to the IMS circuitry  508  to indicate that the UE has transitioned or will transition to the CE mode B. Thereafter, the IMS server  512  may send an SIP invite  520  to the IMS circuitry  508  of the UE. The SIP  520  may be an invitation for the UE to engage in an MT voice call. The IMS circuitry  508  may send a message  524  to the IMS server  512  to reject the MT voice call in response to the SIP invite  520 . In some embodiments, the message  524  may be a  480  TEMPORARILY UNAVAILABLE message. The IMS circuitry  508  may also send an SIP REGISTER message  528  to deregister the UE from voice services. In some embodiments, the SIP REGISTER message  528  may also deregister the UE from video services. 
     The IMS server  512  may send a confirmation message  532  (e.g., 200 OK) to the IMS circuitry  508  to acknowledge the deregistration of the UE from voice services. At  536 , the IMS server  512  may mark the UE as temporarily not available for voice calls. 
     The CPS  504  may thereafter send a message  540  to the IMS circuitry  508  to indicate that the UE has transitioned or will transition to the CE mode A or normal coverage mode. The CPS  504  may send the message  540 , for example, if radio conditions on the wireless communication network have improved above a signal quality level. The IMS circuitry  508  may send an SIP register message  544  to the IMS server  512  responsive to the message  540 . The SIP register message  544  may re-register the UE for voice services. The IMS server  512  may delete and/or modify the stored mark that the UE was not available for voice calls. Accordingly, the UE may again be available to receive MT voice calls via the IMS server  512 . 
       FIG. 6  illustrates a signal flowchart of a process  600 , and depicts various signals that may be communicated between a CPS  604 , an IMS circuitry  608 , and an IMS server  612  during the process  600 . The CPS  604  and IMS circuitry  608  may be included in a UE (e.g., UE  104 ), and may correspond to the CPS  212  and IMS circuitry  214  of  FIG. 2 . The IMS server  612  may correspond to the IMS server  112  of  FIG. 1  and/or IMS server  300  of  FIG. 3 . The process  600  depicted in  FIG. 6  may use a new message (different from the SIP register message) to both reject the SIP invite and deregister the UE from voice services in response to receiving an SIP invite when the UE is in the CE mode B. 
     As shown, the CPS  604  may send an indication  616  to the IMS circuitry  608  to indicate that the UE has transitioned or will transition to the CE mode B. Thereafter, the IMS server  612  may send an SIP invite  620  to the IMS circuitry  608  of the UE. The SIP  620  may be an invitation for the UE to engage in an MT voice call. The IMS circuitry  608  may send a message  624  to the IMS server  612  in response to the SIP invite  620 . The message  624  may indicate to the IMS server  612  that the SIP invite  620  is rejected and that the UE requests deregistration from voice services. In some embodiments, the message  624  may also deregister the UE from video services. Furthermore, in some embodiments, the message  624  may omit one or more fields that are included in an SIP register message, thereby conserving message size. 
     At  628 , the IMS server  612  may mark the UE as temporarily not available for voice calls. The CPS  604  may thereafter send a message  632  to the IMS circuitry  608  to indicate that the UE has transitioned or will transition to the CE mode A or normal coverage mode. The CPS  604  may send the message  632 , for example, if radio conditions on the wireless communication network have improved above a signal quality level. The IMS circuitry  608  may send an SIP register message  636  to the IMS server  612  responsive to the message  632 . The SIP register message  636  may re-register the UE for voice services. The IMS server  612  may delete and/or modify the stored mark that the UE was not available for voice calls. Accordingly, the UE may again be available to receive MT voice calls via the IMS server  612 . 
     Embodiments described herein may be implemented into a system using any suitably configured hardware and/or software.  FIG. 2  illustrates, for one embodiment, example components of an electronic device  200 . As discussed above, the electronic device  200  may be, implement, be incorporated into, or otherwise be a part of a UE (e.g., UE  104  and/or UE  108 ) or another device, such as an access point (e.g., access point  116  and/or  120 ) or IMS server (e.g., IMS server  112 ). Additionally, as discussed above, the electronic device  200  may include application circuitry  202 , baseband circuitry  204 , Radio Frequency (RF) circuitry  206 , front-end module (FEM) circuitry  208  and one or more antennas  210 , coupled together at least as shown. In embodiments where the electronic device  200  is implemented in or by an access point or IMS server, the electronic device  200  may also include network interface circuitry (not shown) for communicating over a wired interface (for example, an X2 interface, an S1 interface, and the like). 
     The application circuitry  202  may include one or more application processors. For example, the application circuitry  202  may include circuitry such as, but not limited to, one or more single-core or multi-core processors  202   a . The processor(s)  202   a  may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors  202   a  may be coupled with and/or may include computer-readable media  202   b  (also referred to as “CRM  202   b ”, “memory  202   b ”, “storage  202   b ”, or “memory/storage  202   b ”) and may be configured to execute instructions stored in the CRM  202   b  to enable various applications and/or operating systems to run on the system. 
     The baseband circuitry  204  may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry  204  may include one or more baseband processors and/or control logic to process baseband signals received from a receive signal path of the RF circuitry  206  and to generate baseband signals for a transmit signal path of the RF circuitry  206 . Baseband circuitry  204  may interface with the application circuitry  202  for generation and processing of the baseband signals and for controlling operations of the RF circuitry  206 . For example, in some embodiments, the baseband circuitry  204  may include a second generation (2G) baseband processor  204   a , third generation (3G) baseband processor  204   b , fourth generation (4G) baseband processor  204   c , and/or other baseband processor(s)  204   d  for other existing generations, generations in development or to be developed in the future (e.g., fifth generation (5G), 6G, etc.). The baseband circuitry  204  (e.g., one or more of baseband processors  204   a - d ) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry  206 . The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, and the like. In some embodiments, modulation/demodulation circuitry of the baseband circuitry  204  may include Fast-Fourier Transform (FFT), precoding, and/or constellation mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry  204  may include convolution, tail-biting convolution, turbo, Viterbi, and/or Low Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments. 
     In some embodiments, the baseband circuitry  204  may include elements of a protocol stack such as, for example, elements of an evolved universal terrestrial radio access network (E-UTRAN) protocol including, for example, physical (PHY), media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), and/or radio resource control (RRC) elements. A central processing unit (CPU)  204   e  of the baseband circuitry  204  may be configured to run elements of the protocol stack for signaling of the PHY, MAC, RLC, PDCP and/or RRC layers. In various embodiments, baseband circuitry  204  may implement the CPS  212  of a UE (e.g., UE  104  and/or UE  108 ) as described herein. 
     In some embodiments, the baseband circuitry may include one or more audio digital signal processor(s) (DSP)  204   f  The audio DSP(s)  204   f  may include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. The baseband circuitry  204  may further include computer-readable media  204   g  (also referred to as “CRM  204   g ”, “memory  204   g ”, “storage  204   g ”, or “memory/storage  204   b ”). The CRM  204   g  may be used to load and store data and/or instructions for operations performed by the processors of the baseband circuitry  204 . For example, the CRM  204   g  may load and store data and/or instructions that, when executed by one or more processors of the baseband circuitry  204 , cause the baseband circuitry  204  to implement the techniques described herein, such as aspects of the process  500  and/or  600 . 
     CRM  204   g  for one embodiment may include any combination of suitable volatile memory and/or non-volatile memory. The CRM  204   g  may include any combination of various levels of memory/storage including, but not limited to, read-only memory (ROM) having embedded software instructions (e.g., firmware), random access memory (e.g., dynamic random access memory (DRAM)), cache, buffers, etc.). The CRM  204   g  may be shared among the various processors or dedicated to particular processors. Components of the baseband circuitry  204  may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry  204  and the application circuitry  202  may be implemented together, such as, for example, on a system on a chip (SOC). 
     In some embodiments, the baseband circuitry  204  may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry  204  may support communication with an E-UTRAN and/or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN). Embodiments in which the baseband circuitry  204  is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry. 
     RF circuitry  206  may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry  206  may include switches, filters, amplifiers, etc., to facilitate the communication with the wireless network. RF circuitry  206  may include a receive signal path that may include circuitry to down-convert RF signals received from the FEM circuitry  208  and provide baseband signals to the baseband circuitry  204 . RF circuitry  206  may also include a transmit signal path that may include circuitry to up-convert baseband signals provided by the baseband circuitry  204  and provide RF output signals to the FEM circuitry  208  for transmission. 
     In some embodiments, the RF circuitry  206  may include a receive signal path and a transmit signal path. The receive signal path of the RF circuitry  206  may include mixer circuitry  206   a , amplifier circuitry  206   b  and filter circuitry  206   c . The transmit signal path of the RF circuitry  206  may include filter circuitry  206   c  and mixer circuitry  206   a . RF circuitry  206  may also include synthesizer circuitry  206   d  for synthesizing a frequency for use by the mixer circuitry  206   a  of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry  206   a  of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry  208  based on the synthesized frequency provided by synthesizer circuitry  206   d . The amplifier circuitry  206   b  may be configured to amplify the down-converted signals and the filter circuitry  206   c  may be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry  204  for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although this is not a requirement. In some embodiments, mixer circuitry  206   a  of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect. 
     In some embodiments, the mixer circuitry  206   a  of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry  206   d  to generate RF output signals for the FEM circuitry  208 . The baseband signals may be provided by the baseband circuitry  204  and may be filtered by filter circuitry  206   c . The filter circuitry  206   c  may include a low-pass filter (LPF), although the scope of the embodiments is not limited in this respect. 
     In some embodiments, the mixer circuitry  206   a  of the receive signal path and the mixer circuitry  206   a  of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion and/or upconversion, respectively. In some embodiments, the mixer circuitry  206   a  of the receive signal path and the mixer circuitry  206   a  of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry  206   a  of the receive signal path and the mixer circuitry  206   a  of the transmit signal path may be arranged for direct downconversion and/or direct upconversion, respectively. In some embodiments, the mixer circuitry  206   a  of the receive signal path and the mixer circuitry  206   a  of the transmit signal path may be configured for super-heterodyne operation. 
     In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In these alternate embodiments, the RF circuitry  206  may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry  204  may include a digital baseband interface to communicate with the RF circuitry  206 . 
     In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect. 
     In some embodiments, the synthesizer circuitry  206   d  may be a fractional-N synthesizer or a fractional N/N+1 synthesizer, although the scope of the embodiments is not limited in this respect, as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry  206   d  may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider. The synthesizer circuitry  206   d  may be configured to synthesize an output frequency for use by the mixer circuitry  206   a  of the RF circuitry  206  based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry  206   d  may be a fractional N/N+1 synthesizer. 
     In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO), although that is not a requirement. Divider control input may be provided by either the baseband circuitry  204  or the application circuitry  202  depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a look-up table based on a channel indicated by the application circuitry  202 . 
     Synthesizer circuitry  206   d  of the RF circuitry  206  may include a divider, a delay-locked loop (DLL), a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by either N or N+1 (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle. 
     In some embodiments, synthesizer circuitry  206   d  may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fLO). In some embodiments, the RF circuitry  206  may include an IQ/polar converter. 
     FEM circuitry  208  may include a receive signal path that may include circuitry configured to operate on RF signals received from one or more antennas  210 , amplify the received signals and provide the amplified versions of the received signals to the RF circuitry  206  for further processing. FEM circuitry  208  may also include a transmit signal path that may include circuitry configured to amplify signals for transmission provided by the RF circuitry  206  for transmission by one or more of the one or more antennas  210 . In some embodiments, the FEM circuitry  208  may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry  208  may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include a low-noise amplifier (LNA) to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry  206 ). The transmit signal path of the FEM circuitry  208  may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry  206 ), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas  210 ). 
     In some embodiments, the electronic device  200  may include additional elements such as, for example, a display, a camera, one or more sensors, and/or interface circuitry (for example, input/output (I/O) interfaces or buses) (not shown). In embodiments where the electronic device is implemented in or by a base station (e.g., eNB or gNB) or an access point, the electronic device  200  may include network interface circuitry. The network interface circuitry may be one or more computer hardware components that connect electronic device  200  to one or more network elements, such as one or more servers within a core network or one or more other base stations or access points via a wired connection. To this end, the network interface circuitry may include one or more dedicated processors and/or field programmable gate arrays (FPGAs) to communicate using one or more network communications protocols such as X2 application protocol (AP), S1 AP, Stream Control Transmission Protocol (SCTP), Ethernet, Point-to-Point (PPP), Fiber Distributed Data Interface (FDDI), and/or any other suitable network communications protocols. 
       FIG. 7  illustrates example interfaces of baseband circuitry  204  in accordance with some embodiments. As discussed above, the baseband circuitry  204  of  FIG. 2  may comprise processors and CRM  204   g  utilized by said processors. Each of the processors  204   b ,  204   c ,  204   h ,  204   d , and  204   g  may include a memory interface,  204   b ,  204   c ,  204   h ,  204   d , and  204   g , respectively, to send/receive data to/from the CRM  204   g.    
     The baseband circuitry  204  may further include one or more interfaces to communicatively couple to other circuitries/devices, such as a memory interface  712  (for example, an interface to send/receive data to/from memory external to the baseband circuitry  204 ), an application circuitry interface  714  (for example, an interface to send/receive data to/from the application circuitry  202  of  FIG. 2 ), an RF circuitry interface  716  (for example, an interface to send/receive data to/from RF circuitry  206  of  FIG. 2 ), a wireless hardware connectivity interface  718  (for example, an interface to send/receive data to/from Near Field Communication (NFC) components, Bluetooth® components (for example, Bluetooth® Low Energy), Wi-Fi® components, and other communication components), and a power management interface  720  (for example, an interface to send/receive power or control signals to/from a power management controller. 
       FIG. 8  illustrates communication circuitry  800  according to some aspects. Communication circuitry  800  may be similar to, and substantially interchangeable with components of electronic device  200 . Components as shown in communication circuitry  800  are shown here for illustrative purposes and may include other components not shown here in  FIG. 8 . 
     Communication circuitry  800  may include protocol processing circuitry  805  may correspond to CPU  204   e , processor  202   a , etc. The protocol processing circuitry may implement one or more of MAC, RLC, PDCP, RRC and non-access stratum (“NAS”) functions of a cellular protocol stack (e.g., CPS  212 ). Protocol processing circuitry  805  may include one or more processing cores (not shown, but similar to those described elsewhere herein) to execute instructions and one or more memory structures (not shown, but similar to those described elsewhere herein) to store program and data information. 
     Communication circuitry  800  may further include digital baseband circuitry  810 , which may be similar to baseband processors of the baseband circuitry  204 . The digital baseband circuitry  810  may implement PHY layer functions including one or more of hybrid automatic repeat request (HARQ) functions, scrambling and/or descrambling, coding and/or decoding, layer mapping and/or de-mapping, modulation symbol mapping, received symbol and/or bit metric determination, multi-antenna port pre-coding and/or decoding which may include one or more of space-time, space-frequency or spatial coding, reference signal generation and/or detection, preamble sequence generation and/or decoding, synchronization sequence generation and/or detection, control channel signal blind decoding, and other related functions. 
     Communication circuitry  800  may further include transmit circuitry  815 , receive circuitry  820  and/or antenna array circuitry  830 . 
     Communication circuitry  800  may further include RF circuitry  825 , which may correspond to RF circuitry  206  or FEM  208 . In an aspect of the invention, RF circuitry  825  may include multiple parallel RF chains for one or more of transmit or receive functions, each connected to one or more antennas of the antenna array  830 . 
     In an aspect of the disclosure, protocol processing circuitry  805  may include one or more instances of control circuitry (not shown) to provide control functions for one or more of digital baseband circuitry  810 , transmit circuitry  815 , receive circuitry  820 , and/or radio frequency circuitry  825 . 
     In some embodiments, communication circuitry  800  may be specifically configured for millimeter wave communications. For example, the communication circuitry  800  may have a hybrid beamforming architecture in which precoding and combining are done in both baseband and RF sections. For example, the digital baseband circuitry  810  may implement a baseband precoder (in transmitter) and combiner (in receiver) using digital signal processing, while RF circuitry  825  may implement RF precoding (in transmitter) and combiner (in receiver) using phase shifters. 
       FIG. 9  illustrates protocol layers of a cellular protocol stack  900  that may be implemented in a wireless communication device according to some aspects. Cellular protocol stack  900  may correspond to the CPS  212  of UE  104  in some embodiments. Additionally, or alternatively, one or more layers of the cellular protocol stack  900  may be implemented in an access node (e.g., access node  116  and/or  120 ) or a network function entity, such as an MME. One or more of the protocol layers of cellular protocol stack  900  may perform operations as described herein related to management of operation of a UE in the CE mode B. 
     In some aspects, protocol layers may include one or more of physical layer (PHY)  910 , medium access control layer (MAC)  920 , radio link control layer (RLC)  930 , packet data convergence protocol layer (PDCP)  940 , service data adaptation protocol (SDAP) layer  947 , radio resource control layer (RRC)  955 , and non-access stratum (NAS) layer  957 , in addition to other higher layer functions not illustrated. 
     According to some aspects, protocol layers may include one or more service access points that may provide communication between two or more protocol layers. 
     According to some aspects, PHY  910  may transmit and receive physical layer signals  905  that may be received or transmitted respectively by one or more other communication devices. According to some aspects, physical layer signals  905  may comprise one or more physical channels. 
     According to some aspects, an instance of PHY  910  may process requests from and provide indications to an instance of MAC  920  via one or more physical layer service access points (PHY-SAP)  915 . According to some aspects, requests and indications communicated via PHY-SAP  915  may comprise one or more transport channels. 
     According to some aspects, an instance of MAC  910  may process requests from and provide indications to an instance of RLC  930  via one or more medium access control service access points (MAC-SAP)  925 . According to some aspects, requests and indications communicated via MAC-SAP  925  may comprise one or more logical channels. 
     According to some aspects, an instance of RLC  930  may process requests from and provide indications to an instance of PDCP  940  via one or more radio link control service access points (RLC-SAP)  935 . According to some aspects, requests and indications communicated via RLC-SAP  935  may comprise one or more RLC channels. 
     According to some aspects, an instance of PDCP  940  may process requests from and provide indications to one or more of an instance of RRC  955  and one or more instances of SDAP  947  via one or more packet data convergence protocol service access points (PDCP-SAP)  945 . According to some aspects, requests and indications communicated via PDCP-SAP  945  may comprise one or more radio bearers. 
     According to some aspects, an instance of SDAP  947  may process requests from and provide indications to one or more higher layer protocol entities via one or more service data adaptation protocol service access points (SDAP-SAP)  949 . According to some aspects, requests and indications communicated via SDAP-SAP  949  may comprise one or more quality of service (QoS) flows. 
     According to some aspects, RRC entity  955  may configure, via one or more management service access points (M-SAP), aspects of one or more protocol layers, which may include one or more instances of PHY  910 , MAC  920 , RLC  930 , PDCP  940  and SDAP  947 . According to some aspects, an instance of RRC  955  may process requests from and provide indications to one or more NAS entities via one or more RRC service access points (RRC-SAP)  956 . 
       FIG. 10  illustrates protocol entities that may be implemented in wireless communication devices, including one or more of a user equipment (UE)  1060 , a base station, which may be termed an evolved node B (eNB), or new radio node B (gNB)  1080 , and a network function, which may be termed a mobility management entity (MME), or an access and mobility management function (AMF)  1094 , according to some aspects. The UE  1060  may correspond to the UE  104  and/or UE  108 . Additionally, or alternatively, the gNB  1080  may correspond to the access node  116  and/or access node  120 . 
     According to some aspects, access node  1080  may be implemented as one or more of a dedicated physical device such as a macro-cell, a femto-cell or other suitable device, or in an alternative aspect, may be implemented as one or more software entities running on server computers as part of a virtual network termed a cloud radio access network (CRAN). 
     According to some aspects, one or more protocol entities that may be implemented in one or more of UE  1060 , gNB  1080  and AMF  1094 , may be described as implementing all or part of a protocol stack in which the layers are considered to be ordered from lowest to highest in the order PHY, MAC, RLC, PDCP, RRC and NAS. According to some aspects, one or more protocol entities that may be implemented in one or more of UE  1060 , gNB  1080  and AMF  1094 , may communicate with a respective peer protocol entity that may be implemented on another device, using the services of respective lower layer protocol entities to perform such communication. 
     According to some aspects, UE PHY  1072  and peer entity gNB PHY  1090  may communicate using signals transmitted and received via a wireless medium. According to some aspects, UE MAC  1070  and peer entity gNB MAC  1088  may communicate using the services provided respectively by UE PHY  1072  and gNB PHY  1090 . According to some aspects, UE RLC  1068  and peer entity gNB RLC  1086  may communicate using the services provided respectively by UE MAC  1070  and gNB MAC  1088 . According to some aspects, UE PDCP  1066  and peer entity gNB PDCP  1084  may communicate using the services provided respectively by UE RLC  1068  and 5 GNB RLC  1086 . According to some aspects, UE RRC  1064  and gNB RRC  1082  may communicate using the services provided respectively by UE PDCP  1066  and gNB PDCP  1084 . According to some aspects, UE NAS  1062  and AMF NAS  1092  may communicate using the services provided respectively by UE RRC  1064  and gNB RRC  1082 . 
       FIG. 11  is a block diagram illustrating components, according to some example embodiments, able to read instructions from a machine-readable or computer-readable medium (for example, a non-transitory machine-readable storage medium) and perform any one or more of the processes for management of operation by a UE in the CE mode B discussed herein. Specifically,  FIG. 11  shows a diagrammatic representation of hardware resources  1100  including one or more processors (or processor cores)  1110 , one or more memory/storage devices  1120 , and one or more communication resources  1130 , each of which may be communicatively coupled via a bus  1140 . For embodiments where node virtualization (for example, network function virtualization (“NFV”)) is utilized, a hypervisor  1102  may be executed to provide an execution environment for one or more network slices/sub-slices to utilize the hardware resources  1100 . 
     The processors  1110  (for example, a CPU, a reduced instruction set computing (“RISC”) processor, a complex instruction set computing (“CISC”) processor, a graphics processing unit (“GPU”), a digital signal processor (“DSP”) such as a baseband processor, an application specific integrated circuit (“ASIC”), a radio-frequency integrated circuit (“RFIC”), another processor, or any suitable combination thereof) may include, for example, a processor  1112  and a processor  1114 . The processors may correspond to any processors of the AN  106  or the UE  108  described herein. 
     The memory/storage devices  1120  may include main memory, disk storage, or any suitable combination thereof. The memory/storage devices  1120  may include, but are not limited to, any type of volatile or non-volatile memory such as dynamic random access memory (“DRAM”), static random-access memory (“SRAM”), erasable programmable read-only memory (“EPROM”), electrically erasable programmable read-only memory (“EEPROM”), Flash memory, solid-state storage, etc. The memory/storage devices  1120  may correspond to CRM  202   b  of  FIG. 2 . 
     The communication resources  1130  may include interconnection or network interface components or other suitable devices to communicate with one or more peripheral devices  1104  or one or more databases  1106  via a network  1108 . For example, the communication resources  1130  may include wired communication components (for example, for coupling via a Universal Serial Bus (“USB”)), cellular communication components, near-field communication (“NFC”) components, Bluetooth® components (for example, Bluetooth® Low Energy), Wi-Fi® components, and other communication components. 
     Instructions  1150  may comprise software, a program, an application, an applet, an app, or other executable code for causing at least any of the processors  1110  to perform any one or more of the methodologies discussed herein. 
     The instructions  1150  may cause the processors  1110  to perform the process  500 , the process  600 , or other operations of a UE and/or IMS server described herein. 
     The instructions  1150  may reside, completely or partially, within at least one of the processors  1110  (for example, within the processor&#39;s cache memory), the memory/storage devices  1120 , or any suitable combination thereof. Furthermore, any portion of the instructions  1150  may be transferred to the hardware resources  1100  from any combination of the peripheral devices  1104  or the databases  1106 . Accordingly, the memory of processors  1110 , the memory/storage devices  1120 , the peripheral devices  1104 , and the databases  1106  are examples of computer-readable and machine-readable media. 
     The resources described in  FIG. 11  may also be referred to as circuitry. For example, communication resources  1130  may also be referred to as communication circuitry  1130 . 
     Some non-limiting Examples of various embodiments are provided below. 
     Example 1 is one or more computer-readable media having instructions, stored thereon, that when executed by one or more processors, are to cause a user equipment (UE) to: determine that the UE is to transition to a coverage enhancement (CE) mode B based on radio conditions on a wireless communication network; transition the UE to the CE mode B based on the determination; process a session initiation protocol (SIP) invite received from an internet protocol (IP) multimedia services (IMS) server, the SIP invite to request initiation of a voice call; and reject the SIP invite and deregister the UE from voice services on the wireless communication network in response to the SIP invite and based on operation of the UE in the CE mode B. 
     Example 2 is the one or more media of Example 1, wherein, to deregister the UE from voice services, the instructions, when executed, are to cause the UE to transmit an SIP register message to the IMS server. 
     Example 3 is the one or more media of Example 2, wherein, to reject the SIP invite, the instructions are to cause the UE to transmit a message to the IMS server to indicate that the UE is temporarily unavailable. 
     Example 4 is the one or more media of Example 1, wherein, to reject the SIP invite and deregister the UE from voice services, the instructions, when executed, are to cause the UE to transmit a single message to the IMS server to indicate to the IMS server that the SIP invite is rejected and request deregistration of the UE from voice services. 
     Example 5 is the one or more media of any one of Examples 1 to 4, wherein the instructions, when executed, are further to cause the UE to: determine that the UE is to transition to a CE mode A or a normal coverage mode based on updated radio conditions on the wireless communication network; transition the UE to the CE mode A or the normal coverage mode; and re-register for voice services on the wireless communication network based on the transition to the CE mode A or the normal coverage mode. 
     Example 6 is the one or more media of any one of Examples 1 to 5, wherein the instructions, when executed, are further to cause the UE to reject a mobile originated (MO) call request to initiate a voice call when the UE is in the CE mode B. 
     Example 7 is the one or more media of any one of Examples 1 to 6, wherein the determination and transition are performed when the UE is configured as a data centric UE, and wherein the UE is not to use the CE mode B when the UE is configured as a voice centric UE. 
     Example 8 is the one or more media of any one of Examples 1 to 7, wherein the instructions, when executed, are further to cause the UE to display an indicator to indicate to a user of the UE that voice services are unavailable based on the determination that the UE is to transition to the CE mode B. 
     Example 9 is one or more computer-readable media having instructions, stored thereon, that when executed by one or more processors, are to cause a internet protocol (IP) multimedia services (IMS) server to: transmit a session initiation protocol (SIP) invite to a first user equipment (UE); obtain, from the first UE responsive to the SIP invite, a request to deregister the first UE from voice services on a wireless communication network; obtain a mobile terminated (MT) call trigger from a second UE to initiate an MT call with the first UE; and reject the MT call trigger based on the request to deregister the first UE from voice services. 
     Example 10 is the one or more media of Example 9, wherein the request to deregister is an SIP register message. 
     Example 11 is the one or more media of Example 10, wherein the instructions, when executed, are further to cause the IMS server to obtain a message from the first UE to indicate that the first UE is temporarily unavailable. 
     Example 12 is the one or more media of Example 9, wherein the request to deregister the first UE from voice services is included in a message that also indicates that the SIP invite is rejected. 
     Example 13 is the one or more media of any one of Examples 9 to 12, wherein the instructions, when executed, are further to cause the IMS server to obtain an SIP register message from the first UE to re-register the first UE for voice services. 
     Example 14 is an apparatus to be employed by a user equipment (UE), the apparatus comprising: a cellular protocol stack to determine that radio conditions on a wireless communication network are below a quality level; and internet protocol (IP) multimedia services (IMS) circuitry coupled to the cellular protocol stack. The IMS circuitry is to: receive an indication from the cellular protocol stack that the radio conditions are below the quality level; receive a session initiation protocol (SIP) invite from an IMS server to request initiation of a voice call; and reject the SIP invite and deregister from voice services on the wireless communication network in response to the SIP invite and based on the indication that the radio conditions are below the quality level. 
     Example 15 is the apparatus of Example 14, wherein the IMS circuitry is to transition the UE to a coverage enhancement (CE) mode B based on the indication that the radio conditions are below the threshold. 
     Example 16 is the apparatus of Example 14, wherein the IMS circuitry is to reject the SIP invite and deregister from voice services when the UE is configured as a data centric UE, and wherein the UE is not to use the CE mode B when the UE is configured as a voice centric UE. 
     Example 17 is the apparatus of Example 14, wherein: to reject the SIP invite, the IMS circuitry is to transmit a message to the IMS server to indicate that the UE is temporarily unavailable; and to deregister the UE from voice services, the IMS circuitry is to transmit an SIP register message to the IMS server. 
     Example 18 is the apparatus of Example 14, wherein, to reject the SIP invite and deregister the UE from voice services, the IMS circuitry is to transmit a single message to the IMS server to indicate to the IMS server that the SIP invite is rejected and request deregistration of the UE from voice services. 
     Example 19 is the apparatus of Example 14, wherein the cellular protocol stack is to determine that the radio conditions on the wireless communication network are above a quality level; and wherein the IMS circuitry is to: receive an indication from the cellular protocol stack that the radio conditions are above the quality level; and transmit an SIP register message to the IMS server to re-register for voice services on the wireless communication network based on the indication that the radio conditions are above the quality level. 
     Example 20 is the apparatus of Example 14, wherein the IMS circuitry is further to: receive, from the cellular protocol stack, a mobile originated (MO) call request to request initiation of a voice call; and reject the MO call request based on the indication that the radio conditions are below the quality level. 
     Example 21 is the apparatus of Example 14, wherein the IMS circuitry is further to cause the UE to display an indicator to indicate to a user of the UE that voice services are unavailable based on the indication that the radio conditions are below the quality level. 
     Example 22 is the apparatus of any one of Examples 14 to 21, wherein the radio conditions include one or more of a channel quality indicator (CQI), a received signal received power, a received signal received quality, a received signal strength indicator, a signal-to-noise ratio, or a signal-to-noise-plus-interference ratio, and wherein the quality level corresponds to one or more thresholds. 
     Example 23 is an apparatus to be employed by a user equipment (UE), the apparatus comprising: means to determine that the UE is to transition to a coverage enhancement (CE) Mode B in a wireless communication network; means to transition the UE to the CE mode B based on the determination; means to receive a session initiation protocol (SIP) invite from an internet protocol (IP) multimedia services (IMS) server to request initiation of a mobile terminated (MT) voice call; and means to deregister the UE from voice services on the wireless communication network in response to the SIP invite and based on operation of the UE in the CE mode B. 
     Example 24 is the apparatus of Example 23, wherein the means to deregister the UE from voice services includes: means to transmit an SIP register message to the IMS server and means to transmit a message to the IMS server to indicate that the UE is temporarily unavailable; or means to transmit a single message to the IMS server to indicate to the IMS server that the SIP invite is rejected and request deregistration of the UE from voice services. 
     Example 25 is the apparatus of Example 23 or 24, wherein the means to transition the UE to the CE mode B is to transition the UE to the CE mode B based on the determination when the UE is configured as a data centric UE, and wherein the UE is not to deregister from the voice services when the UE is configured as a voice centric UE. 
     Example 26 is a method to be performed by a user equipment (UE), the method comprising: determining that the UE is to transition to a coverage enhancement (CE) mode B based on radio conditions on a wireless communication network; transitioning the UE to the CE mode B based on the determination; processing a session initiation protocol (SIP) invite received from an internet protocol (IP) multimedia services (IMS) server, the SIP invite to request initiation of a voice call; and rejecting the SIP invite and deregistering the UE from voice services on the wireless communication network in response to the SIP invite and based on operation of the UE in the CE mode B. 
     Example 27 is the method of Example 26, wherein deregistering the UE from voice services includes transmit an SIP register message to the IMS server. 
     Example 28 is the method of Example 27, wherein rejecting the SIP invite includes transmitting a message to the IMS server to indicate that the UE is temporarily unavailable. 
     Example 29 is the method of Example 26, wherein rejecting the SIP invite and deregistering the UE from voice services includes transmitting a single message to the IMS server to indicate to the IMS server that the SIP invite is rejected and request deregistration of the UE from voice services. 
     Example 30 is the method of any one of Examples 26 to 29, further comprising determining that the UE is to transition to a CE mode A or a normal coverage mode based on updated radio conditions on the wireless communication network; transitioning the UE to the CE mode A or the normal coverage mode; and re-registering for voice services on the wireless communication network based on the transition to the CE mode A or the normal coverage mode. 
     Example 31 is the method of Examples 26 to 30, further comprising rejecting a mobile originated (MO) call request to initiate a voice call when the UE is in the CE mode B. 
     Example 32 is the method of any one of Examples 26 to 31, wherein the determining and transitioning are performed when the UE is configured as a data centric UE, and wherein the UE is not to use the CE mode B when the UE is configured as a voice centric UE. 
     Example 33 is the method of any one of Examples 26 to 32, further comprising displaying, on a display of the UE, an indicator to indicate to a user of the UE that voice services are unavailable based on the determination that the UE is to transition to the CE mode B. 
     Example 34 is a method to be performed by an internet protocol (IP) multimedia services (IMS) server, the method comprising: transmitting a session initiation protocol (SIP) invite to a first user equipment (UE); obtaining, from the first UE responsive to the SIP invite, a request to deregister the first UE from voice services on a wireless communication network; obtaining a mobile terminated (MT) call trigger from a second UE to initiate an MT call with the first UE; and rejecting the MT call trigger based on the request to deregister the first UE from voice services. 
     Example 35 is the method of Example 34, wherein the request to deregister is an SIP register message. 
     Example 36 is the method of Example 35, further comprising obtaining a message from the first UE to indicate that the first UE is temporarily unavailable. 
     Example 37 is the method of Example 34, wherein the request to deregister the first UE from voice services is included in a message that also indicates that the SIP invite is rejected. 
     Example 38 is the method of any one of Examples 34 to 37, further comprising obtaining an SIP register message from the first UE to re-register the first UE for voice services. 
     Example 39 is an apparatus comprising means to perform the method of any one of claims  26  to  38 . 
     Example 40 is an apparatus comprising circuitry to perform the method of any one of claims  26  to  38 . 
     The present disclosure is described with reference to flowchart illustrations or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations or block diagrams, and combinations of blocks in the flowchart illustrations or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart or block diagram block or blocks. 
     These computer program instructions may also be stored in a computer-readable medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instruction means that implement the function/act specified in the flowchart or block diagram block or blocks. 
     The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions that execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart or block diagram block or blocks. 
     The description herein of illustrated implementations, including what is described in the Abstract, is not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed. While specific implementations and examples are described herein for illustrative purposes, a variety of alternate or equivalent embodiments or implementations calculated to achieve the same purposes may be made in light of the above detailed description, without departing from the scope of the present disclosure, as those skilled in the relevant art will recognize.

Metadata:
Filing Date: 20180131
Publication Date: 20210504
Grant Date: 20210504
Priority Date: 20170210
Inventors: SOLIMAN, AHMED
Yousef Abdelrahman Mostafa, Amr Abdelrahman
PARRON, JEROME
JAIN, PUNEET
Assignee: APPLE INC
CPC Classifications: [{"code": "H04L65/1104", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L65/1016", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L65/1104", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W16/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04Q2213/13274", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W4/70", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W48/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W4/70", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L65/1016", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W76/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L65/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W60/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04Q2213/13274", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L65/1073", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W60/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L65/1073", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L65/1083", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L65/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L65/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04Q2213/13274", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L65/1073", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L65/1006", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W4/70", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L65/1083", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W60/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L65/1016", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W16/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W76/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L65/1083", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 61274330