Paging control node, session control node and control method

Abstract

The present application relates to a paging control node, a session control node, and a control method. A method of operating a wireless communication device (101), comprising: when operating in disconnected mode (302) relative to a communication network (99, 100, 100-1, 100-2), receiving a paging message (4025) from the communication network (99, 100, 100-1, 100-2), the paging message indicating an incoming call. The method also comprises: upon detecting at least one busy event, sending a response message (4030) associated with the paging message (4025) to the communication network (99, 100, 100-1, 100-2), the response message (4030) indicating that the wireless communication device (101) is temporarily busy.

Description

Technical Field

[0001] Various examples of the present disclosure generally relate to a paging process for a wireless communication device that, in response to receiving a paging message, sends a response message indicating that the wireless communication device is temporarily unable to respond to an incoming data transmission. Various examples of the present disclosure generally relate to buffering data transmission control information associated with the data transmission until a busy event is resolved. Background Art

[0002] Mobile communications using wireless communication devices (sometimes also referred to as user equipment, UE) are widespread. In order to reduce the power consumption of the UE, the UE can switch from a connected mode (during the connected mode, the UE can participate in one or more data transmissions) to a disconnected mode (during the disconnected mode, data transmission is at least suspended). Examples of disconnected modes include the Third Generation Partnership (3GPP) New Radio (NR) Radio Resource Control (RRC) idle mode and the RRC inactive mode. Various implementations of the disconnected mode are known, but generally, re-conversion from the disconnected mode to the connected mode can be triggered by a paging procedure. Here, one or more paging signals are sent to the UE at a paging occasion (PO). This triggers the re-conversion from the disconnected mode to the connected mode, for example, by implementing a random access procedure.

[0003] It has been observed that triggering a re-transition from disconnected mode to connected mode in response to receiving one or more paging signals can be inefficient in terms of flexibility and power consumption. To address this issue, it is known that the UE can signal that it is temporarily busy (WO 2020 / 076460A1). The paging process can then be stopped and no further data can be sent to the UE.

[0004] Even situations may arise where such a busy indication has limited flexibility and is inefficient in terms of power consumption. Summary of the Invention

[0005] Therefore, there is a need for advanced techniques for processing incoming data transmissions directed to wireless communication devices. There is a need for advanced techniques for implementing related paging procedures. In particular, there is a need for techniques that overcome or mitigate at least some of the above-mentioned limitations or disadvantages.

[0006] A method for operating a user equipment (UE) is provided. The method includes receiving a paging message. The paging message indicates a data transmission. The paging message is received from a communication network. The method also includes sending a response message to the communication network, for example, upon detecting at least one busy event. The response message indicates that the wireless communication device is temporarily busy.

[0007] A temporarily busy wireless communication device may correspond to a wireless communication device that is temporarily unable to participate in data transmission.

[0008] The data transmission may be directed to a wireless communication device.SUMMARY OF THE INVENTION The intended recipient or end node of the data transmission may be a wireless communication device or a user associated with the wireless communication device.

[0009] For example, the data transmission may be an incoming call.Here, the temporarily busy wireless communication device may correspond to a wireless communication device that is temporarily unable to respond to the incoming call.

[0010] The response message may be associated with the paging message. This may mean that the response message is sent in the resources of the time-frequency resource grid indicated by the paging message. The response message may include a pointer to the paging message.

[0011] The paging message may be received while operating in a disconnected mode (eg, an inactive mode or an idle mode) with respect to the communication network.

[0012] For example, the response message may include an indicator indicating an expected duration that the wireless communication device will be busy.

[0013] A computer program, a computer program product, or a computer-readable storage medium includes program code. The program code is executable by at least one processor. Execution of the program code causes the at least one processor to perform a method for operating a UE. The method includes receiving a paging message while operating in disconnected mode relative to a communication network. The paging message indicates a data transmission. The paging message is received from the communication network. The method also includes, upon detecting at least one busy event, sending a response message associated with the paging message to the communication network. The response message indicates that the wireless communication device is temporarily busy.

[0014] A wireless communication device includes control circuitry. The control circuitry is configured to receive a paging message from a communication network. The paging message indicates a data transmission. The control circuitry is further configured to send a response message associated with the paging message to the communication network upon detecting at least one busy event. The response message indicates that the wireless communication device is temporarily busy.

[0015] A method for operating a paging control node of a communications network is provided. The method includes triggering a paging procedure to page the wireless communications device upon detecting a data transmission from the wireless communications device. The method also includes receiving a response message from the wireless communications device. The response message indicates that the wireless communications device is temporarily busy. The method also includes providing an indicator to a session control node indicating that the wireless communications device cannot participate in the data transmission. The session control node is associated with the data transmission. This facilitates buffering of data transmission control information associated with the data transmission.

[0016] For example, the indicator indicating that the wireless communication device cannot participate in data transmission may indicate that the wireless communication device is busy. It is also possible that the indicator indicating that the wireless communication device cannot participate in data transmission indicates that the wireless communication device is unreachable and / or unable to respond and / or the paging procedure failed.

[0017] The indicator indicating that the wireless communication device is unavailable may include an indicator of an estimated duration. The estimated duration may indicate how long the UE will be unable to participate in data transmission.

[0018] Detecting the data transmission may include receiving a paging request from a session control node associated with the data transmission.

[0019] A computer program, a computer program product, or a computer-readable storage medium includes program code. The program code can be loaded and executed by at least one processor. When executing the program code, the at least one processor performs a method for operating a paging control node of a communications network. The method includes triggering a paging procedure to page the wireless communications device upon detecting a data transmission from the wireless communications device. The method also includes receiving a response message from the wireless communications device. The response message indicates that the wireless communications device is temporarily busy. The method also includes providing an indicator to a session control node indicating that the wireless communications device cannot participate in the data transmission. The session control node is associated with the data transmission. This facilitates buffering of data transmission control information associated with the data transmission.

[0020] A paging control node of a communication network includes control circuitry. The control circuitry is configured to trigger a paging procedure to page the wireless communication device upon detecting a data transmission from the wireless communication device. The method further includes receiving a response message from the wireless communication device. The response message may be associated with the paging message. The response message indicates that the wireless communication device is temporarily busy. The method further includes providing an indicator to a session control node indicating that the wireless communication device cannot participate in the data transmission. The session control node is associated with the data transmission. This facilitates buffering of data transmission control information associated with the data transmission.

[0021] A method for operating a session control node of a communications network is provided. The method includes, upon detecting an incoming data transmission from a wireless communications device, determining that the wireless communications device is temporarily unable to participate in the incoming data transmission. Then, in response to determining that the wireless communications device is temporarily unable to participate in the incoming data transmission, data transmission control information for the data transmission may be buffered. Then, upon completion of the buffering, provision of the data transmission control information to the wireless communications device may be facilitated.

[0022] For example, the determination that the wireless communication device is temporarily unable to participate in data transmission may include obtaining an indicator from a paging control node indicating that the wireless communication device is temporarily busy.

[0023] A computer program, a computer program product, or a computer-readable storage medium includes program code. The program code is executable by at least one processor. When executing the program code, the at least one processor performs a method for operating a session control node of a communications network. The method includes, upon detecting an incoming data transmission from a wireless communication device, determining that the wireless communication device is temporarily unable to participate in the incoming data transmission. Then, in response to determining that the wireless communication device is temporarily unable to participate in the incoming data transmission, data transmission control information for the data transmission may be buffered. Then, upon completion of the buffering, provision of the data transmission control information to the wireless communication device may be facilitated.

[0024] The session control node includes control circuitry. The control circuitry is configured to, upon detecting a data transmission by a wireless communication device, determine that the wireless communication device is temporarily unable to participate in the data transmission. Then, in response to the determination that the wireless communication device is temporarily unable to participate in the data transmission, buffer data transmission control information for the data transmission. Then, for example, upon completion of the buffering, the data transmission control information may be provided to the wireless communication device.

[0025] It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the respective combination indicated but also in other combinations or alone, without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A communication network including a UE, a cellular network and a data network according to various examples is schematically illustrated.

[0027] Figure 2 Schematically illustrating multiple subscriber identities of a multi-SIM device associated with multiple cellular networks according to various examples.

[0028] Figure 3 Multiple operating modes of a UE according to various examples are shown.

[0029] Figure 4 A session control node of a cellular network according to various examples is schematically illustrated.

[0030] Figure 5 A paging control node of a cellular network according to various examples is schematically illustrated.

[0031] Figure 6 UEs according to various examples are schematically illustrated.

[0032] Figure 7 is a flow chart of a method according to various examples.

[0033] Figure 8 is a flow chart of a method according to various examples.

[0034] Figure 9 is a flow chart of a method according to various examples.

[0035] Figure 10 is a signaling diagram of communications between multiple nodes according to various examples. DETAILED DESCRIPTION

[0036] Some examples of the present disclosure generally provide multiple circuits or other electrical devices. All references to circuits and other electrical devices and the functions provided by each are not intended to be limited to only what is shown and described herein. Although specific labels may be assigned to the various circuits or other electrical devices disclosed, such labels are not intended to limit the operating scope of the circuits and other electrical devices. Based on the specific type of electrical implementation desired, such circuits and other electrical devices can be combined and / or separated from each other in any manner. It should be recognized that any circuit or other electrical device disclosed herein may include any number of microcontrollers, graphics processor units (GPUs), integrated circuits, memory devices (e.g., flash memory, random access memory (RAM), read-only memory (ROM), electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM) or other operating software thereof that cooperate with each other to perform the operations disclosed herein. In addition, any one or more electrical devices may be configured to execute program code contained in a non-transitory computer-readable medium programmed to perform any number of the functions disclosed.

[0037] Below, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the following description of the embodiments should not be construed as limiting. The scope of the present invention is not intended to be limited by the embodiments or drawings described below, which are intended to be illustrative only.

[0038] The accompanying drawings are to be considered as schematic representations, and the elements shown in the drawings are not necessarily shown to scale. Instead, the various elements are represented so that their functions and general purposes become apparent to those skilled in the art. Any connection or coupling between the functional blocks, devices, components or other physical or functional units shown in the accompanying drawings or described herein may also be achieved through indirect connections or couplings. Couplings between components may also be established through wireless connections. Functional blocks may be implemented in hardware, firmware, software or a combination thereof.

[0039] Various examples relate to wireless communications in a communication network. The communication network may include a UE and a cellular network. The communication network may include one or more data networks, such as an IP Multimedia Subsystem (IMS) network. The cellular network (NW) may include a radio access network (RAN) and a core network (CN). The RAN may include one or more base stations associated with multiple cells. A wireless link may be used to transmit signals encoding data between a wireless communication device and the RAN.

[0040] The UE can selectively operate in connected mode or disconnected mode. These modes are defined in conjunction with operations on the cellular network. More specifically, the modes can be defined for the RAN and, optionally, the CN. Disconnected mode reduces or even eliminates communications on the radio link between the UE and the RAN, thereby reducing power consumption. To trigger the transition from disconnected mode to connected mode, a paging procedure can be used. According to various examples described herein, the paging procedure can include the transmission of one or more paging signals. One or more paging signals can be sent at a paging occasion (PO). PO can be aligned with the ON duration of a discontinuous reception cycle (DRX) implemented by the UE. The one or more paging signals can include a paging indicator, typically sent on a control channel and received using blind decoding. The one or more paging signals can encode a paging message, which is typically received on time-frequency resources of a time-frequency resource grid indicated by the paging indicator. The paging message may indicate a paging cause. The value of the paging cause can indicate the reason why the communication network has triggered the paging procedure. Example paging causes may include: incoming data transmissions, such as incoming calls; measurement requests; positioning requests; emergency alerts, such as ETWS / CMAS alerts; and / or system information; etc. Incoming data transmissions are sometimes labeled mobile terminal (MT) data transmissions.

[0041] The various examples described herein relate to a wireless communication device capable of connecting to at least one cellular NW using multiple UE identifiers. Such a UE is referred to as a multi-SIM device. According to the various examples described herein, the term UE identifier used herein may refer to an identifier associated with a user associated with the UE, i.e., a user identifier (for simplicity, hereinafter, this is simply referred to as an identifier). These identifiers may include temporary identifiers assigned to the UE. For example, such a UE capable of connecting to at least one cellular NW using one or more identifiers may include multiple SIM chip cards or multiple embedded SIM modules. Hereinafter, such a UE capable of connecting to at least one cellular NW using multiple identifiers will be referred to as a multi-SIM device. Multiple identifiers are typically associated with different subscriptions at each cellular NW or multiple cellular NWs. Such subscriptions are associated with a unique identifier (e.g., an International Mobile Subscriber Identity (IMSI)) and a unique service agreement. For example, policies and billing and / or traffic shaping for data transmission such as voice calls, short message services, and packet data may depend on the corresponding service model. According to the various examples described herein, if a multi-SIM device connects to at least one cellular NW using a first identifier, a corresponding IP address, a unique mobile station international subscriber directory number, and a unique data connection to the cellular NW may be provided. The multi-SIM device then operates in connected mode relative to the cellular NW. Typically, when the multi-SIM device operates in connected mode using a first identity, the multi-SIM device will operate in disconnected mode using a second identity relative to the same cellular NW or another cellular NW associated with the second identity. This is particularly true for so-called single-radio multi-SIM devices that lack dual transmit and / or receive (transmit) capabilities.

[0042] The PO for disconnected mode may be aligned with an absence time or paging gap associated with a connected mode of another identity of the multi-SIM device. It is possible to provide a paging gap that corresponds to an absence time relative to the cellular NW to which the UE operates in connected mode; during the absence time, the UE may perform channel measurements with respect to the cellular NW associated with the second identity and / or monitor one or more paging signals from the cellular NW associated with the second identity. Based on the various examples described herein, it can be said that from the perspective of the NW, the multi-SIM device will generally be perceived as two independent UEs.

[0043] According to various examples described herein, a multi-SIM device can use multiple identifiers to connect to the same cellular NW or multiple cellular NWs. For example, some scenarios involving a multi-SIM device connected to multiple cellular NWs are described herein; however, the technology is also applicable to scenarios where a multi-SIM device uses multiple identifiers to connect to the same cellular NW.

[0044] The various techniques are based on the following observation: When a UE (e.g., a single-SIM UE or a multi-SIM device) is paged, there may be various reasons why the UE may or may not prefer to transition from disconnected mode to connected mode in response. The UE may be busy. Some examples of such busy events are listed in Table 1 below.

[0045]

[0046] Table 1: Examples of busy events that may trigger the sending of a response message associated with a paging message, indicating that the UE is temporarily unable to respond. It is possible that multiple such busy events may be encountered in a cumulative manner at a given time.

[0047] Various techniques facilitate buffering control information associated with a data transmission (data transmission control information) that triggers a paging procedure in response to determining that the UE is unable to participate in the data transmission. One reason the UE is unable to participate in the data transmission may be that the UE encounters one or more busy events. The UE may be unable to respond.

[0048] According to the various examples described herein, various options are contemplated for determining that a UE cannot participate in data transmission. Examples of such options are provided in Table 2.

[0049]

[0050] Table 2: Example options for implementing decision criteria to determine whether a UE can or cannot participate in data transmission. A reason why the UE cannot participate in data transmission may be that one or more busy events according to Table 1 are encountered at the UE. Another reason may include that the UE is unreachable.

[0051] Buffering may occur at one or more nodes of the communication NW. More specifically, buffering may occur at a session control node of the communication NW.

[0052] According to various examples described herein, the session control node configured to buffer data transmission control information may be a control node of the CN of the cellular NW. Furthermore, the session control node may be implemented by a data plane gateway of the CN of the cellular NW. In yet another example, the session control node may be implemented by a base station of the RAN. In yet another example, the session control node may be implemented by a node of a data network connected to the cellular network (e.g., an IMS node).

[0053] The buffering of data transmission control information may be extended in duration. For example, the duration may be longer than 30 seconds, optionally longer than 1 minute, further optionally longer than 10 minutes. The buffering may extend until the at least one busy event is resolved. The buffering may be extended until a discard timer expires. More specifically, the buffering may extend beyond the completion of the paging procedure. Therefore, the buffering may also be referred to as an "extended buffer" because it extends beyond the completion of the paging procedure. The buffering of data transmission control information may even extend beyond the waiting time associated with the data transmission. For illustration, a data transmission may be valid for several seconds (e.g., until the originator of the incoming call hangs up, as in the case of an incoming call), but the data transmission control information may be buffered for several minutes or even tens of minutes. By buffering the data transmission control information, an indication of who made the call may then be obtained.

[0054] According to various examples described herein, the buffered data transmission control information can be significantly smaller in size than the payload data of the data transmission, such as a payload data packet. For example, the data transmission control information can indicate one or more parameters of the data transmission. Such parameters can put the UE in a position to re-initiate / start the data transmission. For example, an additional data transmission different from the initial data transmission can be established by the UE. The additional data transmission can carry information associated with the initial input data transmission. This facilitates transmitting the information associated with the data transmission at a later point in time when the at least one busy event is resolved. Some examples of the information content of the data transmission control information: the initiator of the data transmission; the content of the data transmission, such as application type, voice call, video call, call, etc.; the priority of the data transmission; the data transmission expiration time; cryptographic material associated with the encryption of the packet data of the data transmission, such as certificates or cryptographic key material; to name a few.

[0055] Then, when the at least one busy event is resolved, the buffered data transmission control information associated with the data transmission can be provided to the UE. Thus, the UE can be informed of the details of the data transmission that could not be responded to earlier due to the at least one busy event. For example, in the case where the data transmission is a call—such as a voice call or a video call—the corresponding data transmission control information—then referred to as call control information—can be used by the UE to trigger an outgoing call to the initiator of the incoming call. More generally, the UE can trigger further data transmissions to the initiator of the incoming data transmission based on the data transmission control information. This is why it is beneficial to extend the buffering of the data transmission control information, for example, even beyond the validity period of the paging procedure or the incoming data transmission.

[0056] The techniques described above are illustrated using the following example, specifically for the scenario of an incoming data transfer via an incoming call: First, triggered by a paging message indicating an incoming call and received from a communications network, a UE may send a response message in response to the paging message. The response message may be sent to a node of the core network of the cellular communications network. The response message may be sent upon detecting at least one busy event. The response message may indicate that the UE is temporarily unable to respond to the incoming call, or more generally, unable to participate in data transfer. For example, the response message may include a busy indicator. The response message may also include an indicator indicating the estimated duration that the UE will be unable to respond to the incoming call. For example, a scenario in which the UE is a multi-SIM device is conceivable. Here, the at least one busy event may include the UE operating in connected mode using an identifier different from the identifier associated with the paging message. The response message may then indicate a time estimate for how long the UE will be busy using the additional identifier. Generally speaking, a response message indicating that the UE is temporarily unable to respond to the incoming call may indicate to the communications network that the UE may take responsive action to the paging message, or more specifically, the incoming call, at a later time or stage. In the event that the response message indicates an estimated duration for which the UE will be unable to respond to the incoming call, it may be possible to estimate this time based on, for example, settings in the UE. For example, a predetermined lookup table may be relied upon, containing corresponding values ​​for the estimated time, based, for example, on the type of busy event, the type of application associated with the data transmission supported by the connection mode using the additional identifier, a real-time estimate of the remaining time for the data transmission (e.g., based on the remaining size of the packet data to be transmitted), or even real-time user interaction based on a user query (e.g., a user may select a specific duration in minutes from a dialog window). The node receiving the response message may then record that the UE is unreachable due to being busy. The node receiving the response message may record an estimated time when the wireless communication device will become "not busy" or reachable again. The node receiving the response message may forward this information to another node, such as a session control node or a node in the IMS NW, such as the session control node for the incoming call. Based on the response message indicating that the UE is temporarily unable to respond to the incoming call, it may be possible to implement extended buffering of data transmission control information, here implemented by call control information. For illustration, such extended buffering may only be applicable to certain types of data transmission. For example, it is conceivable that extended buffering may be selectively activated for voice or video calls. The decision criteria for selectively activating extended buffering may include: the type of data transmission (e.g., extended buffering may be activated only for calls, but not for other types of data transmission); policies associated with the user (e.g., user level); predetermined settings associated with the user; etc. For example, the data transmission may correspond to an incoming call. The incoming call may be implemented according to the Session Initiation Protocol (SIP).For example, SIP is described by Rosenberg et al. in Internet Society, Request for Comments: 3261 (2002). In this case, an invite message received from the initiator of a call can be buffered as call control information. Information can also be extracted from the SIP invite message, such as the address of the initiator of the incoming call. For example, if a SIP invite message is buffered, the SIP invite message can be marked as buffered. For example, a corresponding indicator can be incorporated into the header of the SIP invite message. A separate indicator linked to the SIP invite message can also be provided. Similar explanations apply to other types of buffered call control information. Typically, such a tag indicating that data transmission control information has been buffered can be included in the data transmission control information and can be provided separately. Once the UE is available again (i.e., any busy events that previously prevented the UE from directly accepting incoming calls have been resolved), the UE can request the buffered call control information from the communication network. A corresponding request message can be sent. This can be a service request message. The request message can reference a previously sent response message and indicate that the UE is temporarily unable to respond to the incoming call. The request message may also directly reference the incoming call, or more generally, reference mobile terminated data. For example, the request message may reference an expansion buffer of mobile terminated data at the communication NW. Thus, the communication NW is informed that the UE is now ready to receive call control information.

[0057] Based on the request message, a specific node at the communication NW that is buffering the call control information is notified that the UE is now operating in connected mode and is able to receive data. The buffered call control information is then provided to the UE. This can be provided together with a tag for the buffered call control information. When the UE receives the call control information and determines that the call control information has been buffered for an extended duration, it will not directly respond to the incoming call. For example, the caller's identification can be checked. For example, in the case where the call control information is implemented via a SIP invite message, the UE can avoid directly answering the SIP invite message. Instead, the UE can optionally trigger an outgoing call to the initiator of the incoming call based on the call control information. One or more decision criteria for whether to trigger an outgoing call are unimaginable. Example decision criteria include: for example, the duration that the call control information has been buffered; or a user query (for example, manual interaction with the user of the UE). For example, the user can be prompted via a corresponding user interface to indicate whether the user wants to place an outgoing call.

[0058] In the above, a scenario has been described in the context of data transmission achieved by an incoming call. The above concepts can be easily applied to other kinds and types of incoming data transmissions to a UE.

[0059] Figure 1 There is schematically shown a communication NW 99 comprising a UE 101, a cellular NW 100 and a data network (DN) 180, such as an IMS NW. Figure 1 The example of FIG shows a cellular NW 100 according to the 3GPP 5G architecture. Details of the 3GPP 5G architecture are described in 3GPP TS 23.501, version 15.3.0 (2017-09). Figure 1 The following and other parts of the description illustrate the technology in the 3GPP 5G framework for cellular NW, but similar techniques can be easily applied to other communication protocols. Examples include 3GPP LTE 4G - for example, in the MTC or NB-IOT framework - and even non-cellular wireless systems such as IEEE Wi-Fi technology.

[0060] exist Figure 1 In the case of , UE 101 may be connected to cellular NW 100. For example, UE 101 may be one of the following: a cellular phone; a smart phone; an IOT device; an MTC device; a sensor; an actuator; and the like.

[0061] The UE 101 is a multi-SIM device 101: the UE 101 is able to connect to one or more cellular NWs (in Figure 1 Only a single cellular NW is shown in FIG. 4 . The identifiers 451 and 452 may be static (eg, SUPI / IMSI) or temporary (eg, Temporary Mobile Identity (TMSI)). Each of the multiple identifiers 451 and 452 may be implemented by a corresponding SIM such as a USIM.

[0062] UE 101 may be connected to CN 115 of cellular NW 100 via RAN 111, which is typically formed by one or more BSs 112 (for simplicity, the RAN 111 is not shown in FIG. Figure 1 Only a single BS 112 is shown in the figure. A wireless link 114 is established between the RAN 111 (specifically, one or more BSs 112 in the RAN 111) and the UE 101. The wireless link 114 may include one or more spatial streams for transmitting data over the air. The wireless link 114 may also be labeled as a radio channel.

[0063] The wireless link 114 (or radio link) implements a time-frequency resource grid. Typically, orthogonal frequency division multiplexing (OFDM) is used: here, a carrier comprises a plurality of subcarriers. The subcarriers (in the frequency domain) and the symbols (in the time domain) then define the time-frequency resource elements of the time-frequency resource grid. Thereby, the protocol time basis is defined, for example, by the duration of frames and subframes comprising a plurality of symbols, and the start and stop positions of the frames and subframes. Different time-frequency resource elements may be allocated to different logical channels or reference signals of the wireless link 114. Examples include: Physical Downlink Shared Channel (PDSCH); Physical Downlink Control Channel (PDCCH); Physical Uplink Shared Channel (PUSCH); Physical Uplink Control Channel (PUCCH); a channel used for random access; etc.

[0064] The wireless links 114 of the cellular NWs to which the UE 101 connects using its multiple identities 451 , 452 may be different from each other, eg using different frequencies, different modulation and / or coding, etc. There may be a frequency offset between the carrier frequencies of the wireless links 114 of the multiple NWs.

[0065] The CN 115 comprises a user plane (UP) 191 (also commonly referred to as a data plane DP) and a control plane (CP) 192. Application data for a data transmission is typically routed via the UP 191. The data transmission may be associated with the transmission of payload data. For example, this may be a call or payload data of another application. The data transmission may be characterized by an initiator. The data transmission may be between two terminal nodes (identified, for example, in the header of the respective data packets). The data transmission may include multiple data packets. The data transmission may be associated with a dedicated bearer. For this purpose, a UP function node (UPF) 121 is provided. The UPF 121 may implement a router function. The UPF 121 implements a gateway node. Application data may pass through one or more UPFs 121. In Figure 1 In the case of , UPF 121 acts as a gateway with respect to data NW 180 (eg, Internet or local NW or IMS NW). Data transfer application data can be transferred between UE 101 and one or more servers on data NW 180.

[0066] The cellular NW 100 also includes a mobility control node, here implemented by an access and mobility management function (AMF) 131 and a session management function (SMF) 132 .

[0067] The cellular NW 100 further includes: a policy control function (PCF) 133; an application function (AF) 134; an NW slice selection function (NSSF) 134; an authentication server function (AUSF) 136; and a unified data management (UDM) 137. Figure 1Also shown are the protocol reference points N1-N22 between these nodes.

[0068] The AMF 131 provides one or more of the following functions: connection management, sometimes also referred to as registration management; NAS termination for communications between the CN 115 and the UE 101; connection management; reachability management; mobility management; connection authentication; and connection authorization. For example, if the corresponding UE 101 is operating in disconnected mode, the AMF 131 controls CN-initiated paging of the UE 101. Thus, the AMF 131 implements a paging control node. The paging control node can control and trigger the paging process for the UE 101. For this purpose, the paging control node can track the mobility of the UE 101. The paging control node can manage the connection of the UE 101 with the cellular NW 100. The AMF 131 can trigger the transmission of a paging signal to the UE 101; this can be aligned with the PO time. After the UE registers with the NW, the AMF 131 creates a UE context 459 and maintains the UE context for at least as long as the UE 101 is registered with the NW. The UE context 459 may store one or more identities of the UE 101, such as a temporary identity used for paging as described herein. The AMF 131 may also provide the UE 101 with a temporary identity, a TMSI or S-TMSI, or even a paging-related identity, as further described below. The UE context may also store the timing offsets between the POs of the multiple NWs to which the UE is attached. The UE context may also store the timing used to paging the UE (e.g., in milliseconds).

[0069] If the corresponding UE 101 is operating in connected mode, the SMF 132 establishes a data connection 189, which can be used to support data transmission, i.e., to transmit application data for data transmission. Thus, the SMF 132 can implement a session control node. The data connection 189 is characterized by UE subscription information managed by the UDM 137. To track the current mode of the UE 101, the AMF 131 sets the UE 101 to CM Connected or CM Idle. During the CM connection, a non-access stratum (NAS) connection is maintained between the UE 101 and the AMF 131. The NAS connection implements an example of a mobility control connection. The NAS connection can be established in response to paging of the UE 101.

[0070] SMF 132 provides one or more of the following functions: session management, including session establishment, modification, and release, including establishing a UP bearer between RAN 111 and UPF 121; UPF selection and control; configuration of traffic steering; roaming functionality; and termination of at least some NAS messages. Thus, both AMF 131 and SMF 132 implement the CP mobility management required to support mobile UEs.

[0071] A data connection 189 is established between UE 101 and UP 191 of CN 115 toward DN 180 via RAN 111. Thus, a gateway node, such as UPF 121, may also implement a session control node for the data transmission carried by data connection 189. For example, a connection to the Internet or another DN 180 may be established. To establish data connection 189, i.e., to connect to cellular NW 100, the corresponding UE 101 may perform a random access (RACH) procedure, for example, in response to receiving a paging signal. Data connection 189 may include one or more bearers, such as dedicated bearers or default bearers. Data connection 189 may be defined at the RRC layer, typically at layer 3 of the OSI model.

[0072] Although Figure 1 In the case of FIG, a multi-SIM device 101 is shown, but according to various examples described herein, the various techniques described can also be applied to a single SIM UE. Figure 2 Further details regarding the multi-SIM device 101 are described.

[0073] Figure 2 Aspects of the operation of a multi-SIM device 101 are described. Multi-SIM device 101 is configured to communicate with two cellular NWs 100-1 and 100-2. Each cellular NW 100-1 and 100-2 includes a respective RAN 111 and a respective core NW 115. Multi-SIM device 101 communicates with cellular NW 100-1 using a first identifier 451 and communicates with cellular NW 100-2 using a second identifier 452.

[0074] For a single-radio, multi-SIM device 101, the wireless interface is capable of transmitting and receiving signals on only one of the radio links toward the RAN 111 of cellular NWs 100-1 and 100-2 at a given moment. For example, when operating in connected mode with respect to cellular NW 100-1, a paging gap can be defined that serves as an absence time, enabling UE 101 (then operating in disconnected mode with respect to cellular NW 100-2) to monitor for paging signals associated with the second identifier 452, transmitted by the RAN 111 of cellular NW 100-2 during the corresponding absence time. This also applies vice versa. Such an absence time can also be used to send a message to the corresponding cellular NW in response to a paging message.

[0075] During the paging gap, it is possible to perform channel measurements with respect to the cellular NW 100 - 2 , for example, in addition to or instead of monitoring the paging signal of the paging procedure associated with the second identity 452 .

[0076] During the absence time relative to the cellular NW 100 - 1 , the UE may not be required to transmit and / or receive signals to and / or from the cellular NW 100 - 1 .

[0077] Also combined Figure 3 Details about the connected mode and the disconnected mode are shown.

[0078] Figure 3 Schematically shows the UE (eg Figure 1 1 and 2. The UE 101 of FIG. 1 illustrates various aspects of a plurality of modes 301-302 in which the UE 101 may operate. Connected mode 301 is characterized by an established data connection 189, for example, for supporting data transmissions such as calls. Packet data for the data transmissions may be routed along the data connection 189, for example, by reference to an identifier of the data connection 189. During disconnected mode—here, implemented by idle mode 302 (another example would be an inactive mode defined at the RAN 111)—no data connection 189 is established. Connected mode 301 and / or idle mode 302 may include DRX operation. The data connection 189 may be characterized by context information. During connected mode 301, the context information may be kept up to date; during idle mode 300, the context information may be discarded. Thus, in order to be able to transmit packets for the data transmissions, it may be necessary to establish the data connection 189.

[0079] A random access procedure may be performed to trigger the transition from disconnected mode to connected mode 301. The random access procedure may be triggered by various triggering events such as mobile originated (MO) data or mobile terminated (MT) data, and then indicated by a paging UE.

[0080] The release message triggers the transition from connected mode 301 to disconnected mode.

[0081] Figure 4 Schematically illustrated are aspects regarding SMF 132. SMF 132 may implement a session control node.

[0082] According to various examples described herein, a session control node for data transmission is involved in the processing of the data transmission. This may include acting as a gateway node to forward application data for the data transmission and / or control messages for the data transmission, or controlling such a gateway node.

[0083] SMF 132 includes a control circuit 1212 and a memory 1213. The control circuit 1212 can load program code from the memory 1213. The program code can then be executed by the control circuit 1212. SMF 132 also includes an interface 1215. SMF 132 can communicate with other nodes (see Figure 1) communication. When the control circuit 1212 executes the program code, it can perform one or more techniques described herein, such as: determining that a UE that is an intended recipient of a data transmission is temporarily unable to participate in the data transmission, for example based on a corresponding indicator received from a paging control node that performs a paging procedure for the UE; buffering data transmission control information associated with an incoming data transmission, for example while the UE associated with the data transmission is being paged by the paging control node and after the paging procedure has ended, for example in response to determining that the UE is temporarily unable to participate in the data transmission; facilitating provision of the data transmission control information to the UE upon completion of the buffering; marking the data transmission control information to indicate that the data transmission control information has been buffered, for example by including a corresponding indicator in the data transmission control information (e.g., in a header thereof) or by providing a separate indicator that references the data transmission control information; and / or discarding the buffered data transmission control information upon detection of a discard event; and the like.

[0084] Although Figure 4 SMF 132 is shown as an example of a session control node, but in conjunction with Figure 4 The aspects discussed can be readily applied to other kinds and types of session control nodes.Other examples of session control nodes would include: UPF 121, base station 112, node of DN 180.

[0085] SMF 132 is only one example of a session control node. Other implementations of session control nodes are contemplated. For example, session control may be provided by a node of IMS NW 190 or connected to cellular NW 100, 100-1, 100-2 (see Figure 1 Thus, different nodes along the data transmission path defined by, for example, the data connection 189 via the user plane 191 may implement buffering of the data transmission control information.

[0086] Figure 5 Schematically illustrating various aspects of a paging control node implemented here by an AMF 131. The AMF 131 includes a control circuit 1312 and a memory 1313. The control circuit 1312 can load program code from the memory 1313. The program code can then be executed by the control circuit 1312. The AMF 131 also includes an interface 1315. The AMF 131 can communicate with other nodes (see Figure 1) communications. When the control circuitry 1312 executes the program code, it can perform one or more techniques described herein, such as: triggering a paging procedure for the UE, e.g., in response to receiving an indication from a session control node that a data transmission is scheduled for transmission; receiving a response message from the UE, the response message indicating that the UE is temporarily unable to respond to the data transmission; providing an indicator to the session control node indicating that the UE is temporarily unable to participate in the data transmission; initiating and terminating a paging procedure; and / or escalating paging within multiple cells, e.g., to form a tracking area or a group of tracking areas or registration areas; and the like.

[0087] Figure 5 The AMF 131 is shown as a paging control node. In other situations, it is possible that other nodes implement the corresponding functions. For illustration, in 3GPP NR RRC inactive mode, paging can be controlled by the base station 112, which then implements the paging control node. Figure 5 The concepts and aspects discussed can be readily applied to other kinds and types of paging control nodes.

[0088] Figure 6 Schematically, aspects of UE 101 are shown. UE 101 includes a control circuit 1012 and a memory 1013. The control circuit 1012 can load program code from the memory 1013. The program code can then be executed by the control circuit 1012. UE 101 also includes an interface 1015. UE 101 can communicate with other nodes (see FIG. 1015 ) via the interface 1015. Figure 1 ) communication.

[0089] Interface 1015 may include a radio interface to communicate with base station 112 over wireless link 114. The radio interface may include one or more transmitter chains and / or one or more receiver chains. For example, the radio interface may include a single transmitter chain and a single receiver chain, referred to as a single radio. Interface 1015 is capable of communicating using multiple identities, making UE 101 a multi-SIM device.

[0090] When the control circuit 1012 executes the program code, it can perform one or more of the techniques described herein, for example: operating in a connected mode (see Figure 3 : Connected mode 301); operating in disconnected mode (see Figure 3: idle mode 302); transitioning from connected mode to disconnected mode and vice versa; when operating in disconnected mode, monitoring a paging signal to detect a paging indicator, for example by blindly decoding a physical downlink control channel (PDCCH), and upon detecting a paging indicator, attempting to receive a paging message on a resource indicated by the paging indicator; checking whether the paging message is directed to a resource that is consistent with the UE; 101 associated; checking a cause value of the paging message, for example, checking whether the cause value indicates an incoming call or another incoming data transmission; detecting one or more busy events when receiving a paging message; sending a response message associated with the paging message, the response message indicating that the UE is temporarily unable to respond to the incoming data transmission, for example, by including a corresponding indicator (busy indicator) in the response message and optionally by including an indicator indicating an expected duration for which the UE will not be able to respond to the incoming data transmission; obtaining data transmission of control information associated with the incoming data transmission from the communication NW, for example, upon resolving the corresponding busy event (the corresponding busy event previously triggering the sending of a response message indicating that the UE is temporarily unable to respond to the incoming data transmission); and / or starting the incoming data transmission, for example, by triggering another data transmission (for example, an outgoing call) by the initiator of the incoming data transmission; and so on.

[0091] Figure 7 is a flow chart of a method according to various examples. Figure 7 The method may be performed by a UE (eg, a single SIM UE or a multi-SIM device). For example, Figure 7 The method may be performed by a single radio multi-SIM device. Figure 7 The method can be performed by UE 101 (see Figure 6 )implement. Figure 7 The method shows the behavior of the UE in response to paging.

[0092] Figure 7 Frame Figure 7 Marked with dotted lines.

[0093] At block 3010, the UE may check whether a PO has begun. A paging signal of a paging procedure may be sent to the UE during a PO. The repetition timing of the PO may be predetermined. For example, the repetition timing may depend on an identifier associated with the paging. To illustrate, the check at block 3010 may involve determining whether a paging gap has begun: for example, for a multi-SIM device, a paging gap may be aligned with an absence of communication on the radio link using another identifier. Alternatively or additionally, the check at block 3010 may also be based on the on-duration of a discontinuous reception period.

[0094] Once the PO is determined to have started at block 3020, the UE may monitor for paging signals. For example, this may include attempting to receive (monitoring) a paging indicator on the PDCCH and, upon receiving the paging indicator, monitoring the PDSCH for a paging message. Thus, at block 3020, a check is made to see if one or more paging signals are received.

[0095] Then, at block 3030, the UE may receive a paging message. The paging message may indicate an incoming data transmission. For example, in one example of a data transmission, the paging message may indicate an incoming call. For example, the application type associated with the incoming data transmission may be indicated by a cause value included in the paging message.

[0096] Then, at block 3040, the UE may check whether one or more busy events are encountered. For example, the presence of one or more busy events as described in Table 1 above may be checked. An example busy event includes the UE operating in connected mode using another identifier that is different from the identifier associated with the paging message received at block 3030. Another example of a busy event would include a cell edge coverage situation and / or a degraded radio quality situation.

[0097] If no busy event is currently encountered, the method begins at block 3050. Here, the UE may accept paging, for example, by transitioning from disconnected mode (see Figure 3 : Idle mode 302) to connected mode. This may include a random access procedure.

[0098] Otherwise, the method begins at block 3060. At block 3060, when at least one busy event is detected at block 3040, the UE rejects the paging. This may include, for example, sending a response message associated with the paging message, the response message indicating that the UE is temporarily unable to respond to incoming data transmissions. For illustration, in the case of a multi-SIM device, the response message may be sent during an absence time in connected mode using a separate identifier. According to various examples described herein, the absence time at which the response message is sent at block 3060 may be the same absence time as the absence time at which the paging message was received at block 3030, or a subsequent absence time, such as the next absence time according to a recurring timing schedule.

[0099] According to the various examples described herein, in order to send a response message (see Figure 10, 5035), it may not be necessary to use the corresponding identity of the UE to transition to connected mode. For example, the response message can be sent as an early data transmission, such as a message piggybacked into a random access procedure, where the random access procedure can be subsequently aborted. It is possible to send the response message in a contention-based manner on shared resources. It is possible to send the response message in the allocated resources as indicated by the paging message, such as on the PUSCH. The response message can also be sent in resources preconfigured using another message, for example, according to a concept called preconfigured uplink resources (PUR), where resources are preconfigured for use when the UE operates in idle mode.

[0100] The response message may implicitly indicate that the UE is temporarily unable to respond to the incoming call, ie temporarily busy. The response message may also include an explicit indicator (busy indicator). SUMMARY OF THE INVENTION That is, the information content of each information field may be set accordingly.

[0101] In some examples, the response message may include an indicator indicating an expected duration for which the UE will be unable to respond to the incoming data transmission. For illustration, the expected time narration may be indicated in absolute terms with reference to a codebook. Typical durations of the expected duration may be on the order of tens of seconds or even minutes.

[0102] According to the various examples described herein, there are various options that can be used to determine the expected duration. In one example, another identification of the multi-SIM device can be used to monitor the data transmission supported by the connected mode. For example, the average data rate of the data transmission can be checked and compared with the remaining size of the data to be transmitted, and based on these considerations, the expected duration can then be estimated based on said monitoring. Another option for estimating the expected time duration may rely on a user query. For example, the user interface of the UE can be controlled to maintain user feedback on the approximate time until the resolution of one or busy events. For cell edge scenarios or reduced radio quality scenarios, the mobility level of the UE may be taken into account: for higher mobility the expected duration may be shorter.

[0103] At block 3070, a check is made to see if at least one busy event is persistent. For example, this may include performing the same check as performed at block 3040. Block 3070 may be repeated from time to time until the busy event has been resolved.

[0104] Then, at block 3080 , the data transmission control information that has been buffered at the communication NW when the response message is received at block 3060 is requested.

[0105] For example, an explicit request message may be sent. As an alternative to explicitly requesting data transmission control information, it is also possible to simply connect to the cellular NW by switching to connected mode; this may serve as an implicit indication to the cellular NW that data transmission control information should be provided to the UE.

[0106] In the case of sending a request message, the request message may be, for example, a higher layer control message implementing a service request.Thus, it is possible to transmit the request message after resolving at least one busy event and furthermore when transitioning from disconnected mode to connected mode. Figure 7 This transition is also illustrated in FIG by reference to idle mode 302 and connected mode 301. In another example, it is possible that the service request message is sent as an early data transmission, for example piggybacked into the random access message 2 of the 4-step random access procedure.

[0107] The request message may refer to the response message sent at block 3060, or include a corresponding indicator indicating the data transmission also indicated by the paging message 3030 (i.e., duplicating the paging cause value), or include a corresponding indicator indicating that the UE requests the provision of buffered data transmission control information. For illustration, reference is made to an extended buffer for MT data at the communication NW.

[0108] The buffered data transmission control information is then obtained at the UE at block 3090. A corresponding message including the data transmission control information may be received via the wireless link 114.

[0109] The data transmission control information may be marked as buffered. According to the various examples described herein, various options are contemplated for marking the data transmission control information as buffered. Some of these embodiments are summarized in Table 3 below.

[0110]

[0111] Table 3: Various examples of how data transmission control information may be marked as buffered at the communication NW. For example, such a label may be assigned once the data transmission control information has been buffered for a period of time or waiting time associated with the data transmission. For example, such a label may be assigned once the data transmission control information has been buffered in response to receiving an indication that the wireless UE is temporarily unable to participate in the data transmission or is even temporarily busy.

[0112] Taking into account the buffered data transmission control information, the UE can customize the action to be taken based on the data transmission control information. In particular, different actions can be taken for the case where the UE directly responds to the incoming data transmission compared to the case where the UE is unable to directly respond to the incoming data transmission due to being temporarily unable to respond to the incoming data transmission.

[0113] For illustration, in the case where the UE directly responds to an incoming data transmission, the UE may accept the incoming data transmission from the originator. Alternatively, in the case where data transmission control information has been buffered, the UE may establish another data transmission or trigger the establishment of another data transmission to the originator of the incoming data transmission. For example, in the case where the data transmission is achieved via an incoming call, a check may be performed at block 3092 to determine whether an outgoing call to the originator of the incoming call is to be triggered, and if so, this may be performed at block 3095.

[0114] According to various examples described herein, various decision criteria may be considered when determining whether to initiate an incoming data transmission at block 3092. Example decision criteria may include checking whether a timeout duration has elapsed since receiving the paging message at block 3030 or since sending the response message at block 3060. Alternatively or additionally, the decision criteria may be based on a user query.

[0115] Facing from the front Figure 7 As will be appreciated from the discussion above, a UE triggered by a paging message may respond to the paging message by, for example, sending a message to a paging control node, such as an AMF (block 3060). This response message may include a busy indicator and, optionally, a time estimate for how long the UE will be busy, for example, because it is operating in connected mode relative to another cellular NW using another identifier. The response message sent at block 3060 indicates to the communicating NW that it is possible for the UE to take responsive action on the incoming data transmission at a later stage. In particular, the UE may later query to retrieve buffered data transmission control data. A corresponding cause value may be included in a service request message or a dedicated message to query for data transmission control information. The UE may then obtain the data transmission control information. For example, by receiving the data transmission control information in response to a corresponding request, it may be assumed that the data transmission control information has been buffered. Buffered data transmission control information may also be marked accordingly, for example, by setting a corresponding indicator in its header portion.

[0116] The following will be combined Figure 8 Details regarding this process to facilitate buffering of data transmission control information are described.

[0117] Figure 8 is a flow chart of a method according to various examples. Figure 8 The method may be performed by a paging control node, such as an AMF (see Figure 1 : AMF 131) for CN initiated paging, or BS112 for RAN initiated paging. Optional blocks in Figure 8 Marked with dotted lines.

[0118] At block 3105, the paging control node determines whether paging is required. For example, the paging control node may determine whether data transmission is scheduled for the UE. This may be in response to a corresponding control message received, for example, from a gateway node of the UP 191 and / or a session control node such as an SMF (see Figure 1 : SMF 132) or a node of a data NW connected to a cellular NW, such as a node of an IMS (see Figure 1 : Data NW 180). This control message may indicate the type of data transmission. For example, it may indicate the application. For example, it may indicate that the data transmission is an incoming call from the initiator.

[0119] Next, at block 3110 , a paging procedure is triggered. This may include providing a control message to one or more base stations 112 of the RAN 111 .

[0120] Paging upgrades of the paging procedure may be implemented to take into account UE mobility.

[0121] As discussed above in connection with block 3105, a paging process may be triggered and a paging message may be used that indicates the type of data transmission. For example, the paging message may indicate an incoming call or a website push message or a location-based service message or a social network message, to give some examples of data transmission types.

[0122] Next, at block 3115, a response message may be received from the UE. The response message may indicate that the UE is temporarily unable to respond to the incoming data transmission. Thus, block 3115 is identical to Figure 7 The response message may include a busy indicator. The response message may include an indicator indicating an expected duration that the UE cannot respond to the data transmission.

[0123] Next, at block 3120, an indicator indicating that the UE cannot participate in the data transmission is provided to one or more session control nodes associated with the data transmission. There are various options for implementing such an indicator indicating that the wireless communication device is temporarily unable to participate in the data transmission. Some options are shown in Table 4.

[0124]

[0125] Table 4: Provides a possible implementation of an indicator indicating that the UE is temporarily unable to participate in data transmission from the paging control node to the session control node. Such an indicator may facilitate buffering of data transmission control information at the session control node or related nodes. In some examples, it may not even be possible to provide all indications, i.e., not signal the result of the paging procedure.

[0126] Furthermore, where available, it is possible to provide an indication of the expected duration to the session control node. This may be based on a corresponding indicator provided by the UE (e.g. in combination with Figure 7 (As discussed: Block 3060). For example, the indicator may be forwarded. This may help the session control node customize the buffering.

[0127] In response to receiving the response message 3115 indicating that the UE is temporarily unable to respond to the data transmission, the paging control node may also abort any escalation of the paging procedure. This means that paging may be stopped. Alternatively or additionally, one or more further paging procedures associated with further data transmissions may be blocked. For example, paging of the wireless communication device may be suspended for a certain duration.

[0128] As described above, such a technology can facilitate buffering of data transmission control information at the session control node. Figure 9 Further details regarding this buffering of data transmission control information are described.

[0129] Figure 9 is a flow chart of a method according to various examples. Figure 9 The method may be performed by a session control node that processes incoming data transmissions directed to the UE. According to various examples described herein, the session control node may be a CP node or a UP node. An example implementation of the session control node may be an SMF (see Figure 1 ), UPF or a node such as a gateway node of a data NW connected to a cellular NW (eg, IMS NW). Optional boxes are marked with a dotted line.

[0130] At block 3205, data transmission to the UE is queued. Queuing data transmission may mean checking whether a data connection exists (see Figure 1 : Establishing a data connection 189 to the UE, i.e. whether the UE is operating in connected mode (see Figure 3 : Connection mode 301). If this is not the case, the incoming data associated with the data transmission can be stored / buffered and at the same time paging can be requested by sending a corresponding control message to the paging control node (see Figure 8 :Box 3105).

[0131] Next, at block 3210, a determination is made as to whether the UE is unable to participate in the data transmission. According to various examples described herein, various options may be used to implement block 3210. Some options are summarized in Table 5.

[0132]

[0133] Table 5: Options for determining that a UE is temporarily unable to participate in data transmission taking into account data transmission directed to the UE.

[0134] Then, depending on the result of the check at box 3210, the method starts at box 3216 (if the UE is able to participate in the data transmission) or continues at box 3217 (if the UE is not able to participate in the data transmission).

[0135] At block 3216, any data associated with the data transmission may be forwarded to the UE. In response to the successful paging, a data connection may have been simultaneously established. Data may be forwarded along the data connection.

[0136] At block 3217, an optional check may be performed to activate or deactivate buffering of data transmission control information. For example, a basic determination may be made at block 3217 based on the type of incoming data transmission. For example, extended buffering may be activated for incoming calls, but may not be activated for incoming data transmissions belonging to non-call applications (e.g., social network messages).

[0137] If buffering is not activated, the data transmission is rejected at block 3218. For illustration, a corresponding rejection message may be sent to the initiator of the incoming data transmission.

[0138] Otherwise, in block 3219, the data transmission control information may be buffered.

[0139] It is conceivable that the data transmission control information has already been buffered before executing block 3219, ie, as part of block 3205. Buffering may then continue at block 3219.

[0140] Furthermore, in some cases, at block 3219, the data transmission control information may be marked as buffered. For illustration, a corresponding indicator may be provided in the header of the data transmission control information. A separate indicator referencing the data transmission control information may also be provided. Details are explained in Table 3.

[0141] Optionally, a rejection message may also be sent to the initiator of the incoming data transmission. In some examples, such a rejection message may include a cause value indicating buffering implemented at the session control node. This allows the initiator of the incoming data transmission to understand that the UE may initiate other data transmissions associated with the incoming data transmission. According to various examples, the rejection message may also include an estimated time at which the UE will initiate the other data transmission. This may be based on a corresponding timing indication previously obtained from the UE.

[0142] At block 3220, a check is performed to determine whether the UE is capable of responding at the same time. Various options may be used to implement the check at block 3220, according to various examples described herein. For illustration, a corresponding indicator indicating that the UE has become capable of responding to one or other nodes may be monitored. For illustration, a data connection to the UE may be monitored. Monitoring whether the UE has become capable of responding may typically be based on control signaling in the CP or based on monitoring the UP. A request may be received from the UE. For example, in one scenario, the UE may send a request for data transmission control information, which may then be received by the session control node.

[0143] Then, when the UE becomes responsive, data transmission control information is provided to the wireless communication device at block 3220. For example, data plane routing of the data transmission control information is contemplated, such as along a subsequently established data connection. Furthermore, the data transmission control information may be provided to a mobility control node, such as an AMF, which may then forward the data transmission control information to the wireless communication device.

[0144] The check at block 3220 may be re-performed from time to time, for example, until a discard event is met. Therefore, at block 3221, a check is made to determine whether to discontinue buffering of the data transmission control information. This may involve the session control node monitoring for discard events while buffering the call control information. Upon detecting a discard event, the buffered data transmission control information may be discarded, as described below. Example discard events are listed in Table 6 below.

[0145]

[0146] Table 6: Example discard events to consider when deciding whether to discard buffered data transmission control information.

[0147] If buffering of the data transmission control information is suspended, then in block 3222, the data transmission control information is discarded.

[0148] As can be understood from the above, the AMF may notify the session control node that the UE is unreachable due to being "busy." This may be additional information, for example, different from notifying the session control node that a paging call was unsuccessful, meaning that the UE is unreachable. The session control node may then decide whether to not perform extended buffering of the data transfer control information. An example of data transfer control information is buffering of SIP Invite messages. The decision to perform extended buffering may be based on a received "busy indication." Alternatively or additionally, the decision may depend on the type of data transfer; for example, buffering may be selectively performed for incoming calls. For example, the session control node may decide not to buffer the data transfer control information if, for example, the UE is unreachable for other reasons, such as failure to respond to paging, lacking battery power, or being out of coverage. Buffering may begin for a predetermined duration, for example, based on an estimated busy time provided by the UE or a default time such as 5 minutes or 10 minutes. Buffered data transfer control information may be marked as buffered so that the UE understands that it should not respond directly to, for example, the corresponding SIP Invite message. Instead, the UE may take other measures to initiate incoming data transfer, such as, in the case of an incoming call, placing an outgoing call to the initiator of the incoming call.

[0149] Figure 10 It is a signaling diagram for communication between nodes. Figure 10 The scenario is explained in the context of data transmission implemented by a call. Here, the data transmission control information is implemented by call control information. Similar techniques can be easily applied to other types and categories of data transmission.

[0150] At 5005, the originator 199 sends a SIP Invite control message 4005, and the SIP Invite control message 4005 is routed via the UPF 121. Various data packets may include the SIP Invite control message 4005.

[0151] At 5010 , UPF 121 triggers a downlink data notification 4010 to be provided to SMF 132 .

[0152] The SMF 132 then sends a request message 4015 to the AMF 131 at 5015, requesting paging of the UE 101. The request message 4015 may indicate that the incoming data transmission is an incoming call.

[0153] AMF 131 then requests RAN 111 to page UE 101. At 5020, AMF 131 sends a corresponding request message 4020 to RAN 111. Request message 4020 includes a cause value indicating an incoming call.

[0154] Then, the base station 112 ( Figure 104025, and the UE 101 receives the paging message 4025. The paging message 4025 in the illustrated scenario includes a cause value indicating that the paging is the cause of the incoming call. Such a cause value is generally optional.

[0155] UE 101 detects that it is being paged and determines at least one busy event (see Table 1) at 5030, and therefore, UE 101 decides not to respond to the incoming call, i.e., not to participate in the call with initiator 199. For example, UE 101 may be operating in idle mode 302 relative to cellular NW 100 including RAN 111 and further relative to an identity associated with the incoming call. The busy event detected at block 5030 may involve UE 101 operating relative to the cellular NW or relative to another cellular NW and further relative to another identity in connected mode 301 (see Table 1: Embodiment A).

[0156] At 5035, UE 101 sends a response message 4030. Response message 4030 is associated with paging message 5025 and indicates that UE 101 is temporarily unable to respond to the incoming call. Possibly, the response message includes a corresponding busy indicator and / or a corresponding expected duration that the UE will not be able to respond to the incoming call.

[0157] At 5045, the AMF 131 then notifies the SMF 132 that the UE 101 is unreachable due to being busy, and includes an estimated time of unreachability (see Table 2): Option A-Option B is also possible; in addition, see Table 4, Option B-Option A is also possible. A corresponding message 4035 is sent from the RAN 111 to the AMF 131 at 5040, and a corresponding indication 4035 is provided from the AMF 131 to the SMF 132 at 5045.

[0158] The control information is then buffered at the SMF 132 and / or UPF 121 - both SMF 132 and UPF 121 are options for implementing a session control node. For example, a SIP Invite message may be buffered. A buffered SIP Invite message may be marked (see Table 3).

[0159] At block 5055 , one or more busy events are resolved. The UE 101 may then operate in connected mode 301 .

[0160] UE 101 then provides a service request 4040 to AMF 131 (5065) via RAN 111 (5060). Service request 4040 may include a specific cause value indicating that UE 101 has resolved the busy event at 5055 and / or requested data transfer control information. Cause values ​​from service request 4040 from other scenarios, such as MT data or higher latency for CIoT, may also be reused. Based on the context of having previously received response message 4030 including a busy indication, it can be determined that the UE wants to obtain buffered call control information.

[0161] The AMF 131 then sends a notification 4045 to the SMF 132 at 5070, indicating that the UE 101 is now available (see block 3220). For example, in the event that call control information is buffered at the UPF 121, the SMF 132 may trigger the sending of the buffered call control information to the UE 101, for example, by sending a corresponding message 4050 to the UPF 121 at 5075. The UPF 121 may then send the call control information 4055 to the UE 101 at 5080.

[0162] Call control information 4055 may be marked as having been buffered (see Table 3). For example, a corresponding indicator may be included in call control information 4055 itself, or may be sent together with call control information 4055. For illustration, the call control information may have been timestamped, for example, when buffering begins at 5050. Thus, the UE may detect that call control information 4055 is outdated / old and may not directly respond to the SIP Invite associated with call control information 4055. Instead, the UE may trigger a call at 5085 to call back the originator / caller 199 based on information based on call control information 4055. For illustration, UE 101 may extract the address / identity of originator 199 from call control information 4055, for example, from a SIP Invite message.

[0163] Above, combined Figure 10The scenario in which call control information is buffered at a core NW node such as SMF 132 or UPF 121 is described. These are examples only. For illustration, one can imagine a scenario in which call control information is buffered in a node of the data NW that handles an incoming call (e.g., an IMS NW). In yet another example, call control information may be buffered at a base station 112 or more generally at a RAN 111. In particular, the latter scenario may be applicable to implementations such as the disconnected mode with 3GPP NR RRC inactivity. Here, paging is handled by the RAN 111, not by the AMF 131. It is then helpful to buffer the control information of the corresponding base station 112 of the RAN 111 and to pass the call control information when the UE 101 transitions to connected mode 301.

[0164] In summary, techniques associated with a UE paging procedure have been described, where the paging procedure is triggered by an incoming data transmission directed to the UE and an associated indication that the UE is temporarily unable to respond to the incoming data transmission. Specifically, the incoming data transmission may be an incoming call, such as a voice call or a video call.

[0165] This information that the UE is unreachable due to being busy may be forwarded from the paging control node and processed at the core NW or a data NW such as an IMS NW. For example, the AMF may inform the SMF that the UE is unreachable due to being busy.

[0166] Then, a session control node (e.g., a node of a cellular NW or a node of a data NW connected to the cellular NW, e.g., in an IMS node) can decide whether to implement extended buffering of the data transmission control information. Extended buffering can refer to a scenario in which the data transmission control information is retained in the buffer for an extended duration, for example, if compared to a reference scenario in which the data transmission control information is retained in the buffer until the paging procedure is completed. According to the techniques described herein, the data transmission control information can be buffered well after the paging procedure is completed, even if the paging procedure has been escalated.

[0167] Various decision criteria have been described that may be considered by a session control node when determining whether to buffer data transfer control information. For illustration, such decision criteria may include the type of data transfer: for example, call control information may be buffered for data transfers facilitated by a call, but data transfer control information may not be buffered for data transfers facilitated by, for example, a push message received from a web page or another non-call application. Other scenarios are also possible, in which the session control node always implements extended buffering upon receipt of a corresponding indication from the paging control node.

[0168] According to various examples described herein, buffering may be implemented at different nodes, eg in the control plane of the core of the cellular NW - eg at the SMF - in the data plane of the core of the cellular NW - eg at the UPF or at the IMS.

[0169] The buffered data transmission control information can be marked as buffered. For example, an indication or extension field can be appended to the data transmission control information indicating this. To enable the UE to understand, upon eventually receiving the buffered data transmission control information, the UE should not respond directly to it, but rather comment on the data transmission in other ways. For illustration, in the case of an incoming data transmission via an incoming call, the UE extracts the address of the initiator of the incoming call and then places the outgoing call to the initiator of the incoming call, rather than simply responding to the SIP Invite control message.

[0170] According to various examples described herein, the data transmission control message can be automatically provided to the UE, for example, when the UE transitions to connected mode. In other examples, it is also possible for the UE to request the buffered data transmission control information. For example, a SIP service request can be made because the data transmission is being performed as an incoming call. The SIP service request can include a corresponding cause value, or another type of SIP service request message can be defined for this purpose.

[0171] Although the disclosure has been shown and described with respect to certain preferred examples, equivalents and modifications will occur to others skilled in the art upon reading and understanding this specification. The disclosure includes all such equivalents and modifications and is limited only by the scope of the appended claims.

[0172] For illustration, according to various examples, the UE sends a request message requesting buffered data transmission control information. In other examples, the UE may not send such a request message, but the network node monitors whether the UE re-transmits to the connected mode and then triggers the provision of data transmission control information to the UE based on such monitoring.

[0173] Clause 1. A method of operating a wireless communication device (101), the method comprising:

[0174] - while operating in disconnected mode (302) relative to a communication network (99, 100, 100-1, 100-2), receiving a paging message (4025) from said communication network (99, 100, 100-1, 100-2), said paging message indicating an incoming call, and

[0175] - When at least one busy event is detected, sending a response message (4030) associated with the paging message (4025) to the communication network (99, 100, 100-1, 100-2), the response message (4030) indicating that the wireless communication device (101) is temporarily busy.

[0176] Clause 2. The method according to clause 1,

[0177] The response message indicates that the wireless communication device (101) is operating in a connected mode (301) using another user identification (452) that is different from the user identification (451) associated with the paging message (4025).

[0178] Clause 3. The method according to clause 2,

[0179] The response message (4030) is sent during an absence time of the connection mode (301) relative to another communication network (99, 100, 100-1, 100-2) associated with the other user identification (452).

[0180] Clause 4. A method according to any of the preceding clauses,

[0181] The at least one busy event includes detecting at least one of a cell edge coverage situation or a degraded radio quality situation.

[0182] Clause 5. The method according to any of the preceding clauses, further comprising:

[0183] - when the at least one busy event is resolved, obtaining call control information (4055) associated with the incoming call from the communication network (99, 100, 100-1, 100-2),

[0184] The call control information (4055) enables the wireless communication device (101) to initiate an outgoing call to the initiator of the incoming call.

[0185] Clause 6. The method according to clause 5,

[0186] Wherein, the outgoing call is selectively initiated based on at least one of a timeout duration or a user query.

[0187] Clause 7. The method according to clause 5 or 6, further comprising:

[0188] - when said at least one busy event is resolved, requesting said call control information (4055) from said communication network (99, 100, 100-1, 100-2) using a service request control message.

[0189] Clause 8. The method according to clause 7,

[0190] Wherein, the call control information (4055) is requested via the service request control message, which references at least one of the response message (4030), the incoming call or mobile terminated data.

[0191] Clause 9. A method according to clause 7 or 8,

[0192] wherein the call control information (4055) is requested with reference to an extended buffer of mobile terminated data at the communication network (99, 100, 100-1, 100-2).

[0193] Clause 10. The method according to any one of clauses 5 to 9,

[0194] wherein the call control information (4055) is time stamped relative to the incoming call, and / or

[0195] The call control information (4055) is marked as having been buffered at the communication network (99, 100, 100-1, 100-2).

[0196] Clause 11. A method according to any of the preceding clauses,

[0197] Wherein the response message (4030) includes an indicator indicating an expected duration that the wireless communication device (101) will be busy.

[0198] Clause 12. The method according to clause 11, further comprising:

[0199] - using another user identity different from the user identity associated with the paging message (4025) to monitor another data transmission different from the incoming call and supported by connected mode, and

[0200] - estimating said expected duration based on said monitoring.

[0201] Clause 13. The method according to clause 11 or 12, further comprising:

[0202] - estimating the expected duration based on a user query.

[0203] Clause 14. A method of operating a paging control node of a communications network (99, 100, 100-1, 100-2), the method comprising:

[0204] - upon detecting a data transmission for a wireless communication device (101), triggering a paging procedure to page said wireless communication device (101),

[0205] - receiving a response message (4030) from the wireless communication device (101) indicating that the wireless communication device (101) is temporarily busy, and

[0206] - providing an indicator to a session control node (112, 132, 121) associated with the data transmission indicating that the wireless communication device (101) cannot participate in the data transmission, thereby facilitating buffering of data transmission control information (4055) associated with the data transmission.

[0207] Clause 15. The method according to clause 14, further comprising:

[0208] - in response to receiving the response message (4030), aborting the escalation of the paging procedure and / or preventing one or more further paging procedures associated with one or more further data transmissions from being scheduled for the wireless communication device (101).

[0209] Clause 16. A method according to clause 14 or 15,

[0210] wherein the response message (4030) includes an indicator indicating an expected duration for which the wireless communication device (101) will be unable to participate in the data transmission,

[0211] The method further comprises:

[0212] - indicating the expected duration to the session control node (112, 132, 121).

[0213] Clause 17. The method according to any one of clauses 14 to 16,

[0214] The indicator indicating that the wireless communication device (101) is temporarily unable to participate in the data transmission indicates that the wireless communication device (101) is temporarily busy.

[0215] Clause 18. A method of operating a session control node (112, 132, 121) of a communications network (99, 100, 100-1, 100-2), the method comprising:

[0216] - upon detecting a data transmission for wireless communication, obtaining from a paging control node (112, 131) an indicator indicating that the wireless communication device (101) is temporarily busy,

[0217] - in response to obtaining said indicator that said wireless communication device is temporarily busy, buffering data transmission control information for said data transmission (4055), and

[0218] - When the buffering is completed, facilitating provision of the data transmission control information (4055) to the wireless communication device (101).

[0219] Clause 19. The method according to Clause 18,

[0220] wherein the data transmission is an incoming call,

[0221] The data transmission control information (4055) is call control information (4055).

[0222] Clause 20. A method of operating a session control node (111, 112, 132, 121) of a communications network (99, 100, 100-1, 100-2), the method comprising:

[0223] - upon detecting an incoming call for a wireless communication device (101), determining that the wireless communication device (101) is temporarily unable to participate in the incoming call,

[0224] - in response to said determination that said wireless communication device (101) is temporarily unable to participate in said incoming call, buffering call control information (4055) for said incoming call, and

[0225] - When said buffering is completed, facilitating provision of said call control information (4055) to said wireless communication device (101).

[0226] Clause 21. The method according to clause 20,

[0227] The determination that the wireless communication device (101) is temporarily unable to participate in the incoming call is based on an indicator obtained from a paging control node (112, 131) of the communication network (99, 100, 100-1, 100-2) indicating that the wireless communication device (101) is unable to participate in the data transmission.

[0228] Clause 22. A method according to clause 20 or 21,

[0229] Wherein, the determination that the wireless communication device (101) is temporarily unable to participate in the incoming call is based on a timeout duration associated with a response message (4030) from the wireless communication device (101).

[0230] Clause 23. The method according to any one of clauses 19 to 22, further comprising:

[0231] - Mark the call control information (4055) as buffered.

[0232] Clause 24. The method according to any one of clauses 19 to 23, further comprising:

[0233] - while buffering said call control information (4055), monitoring for discard events,

[0234] - When the discard event is detected based on the monitoring, discarding the call control information (4055).

[0235] Clause 25. The method according to Clause 24,

[0236] The discard event is at least one of a timeout of not receiving a triggered response from the wireless communication device (101) or a release indication received from the initiator of the incoming call.

[0237] Clause 26. The method according to any one of clauses 19 to 25,

[0238] Wherein, the call control information (4055) is provided to the wireless communication device (101) according to a corresponding request from the wireless communication device (101).

Claims

1. A method of operating a paging control node, the paging control node being included in a communication network, the method comprising: - upon detecting a data transmission for a wireless communication device, triggering a paging procedure to page said wireless communication device, - receiving a response message from the wireless communication device indicating that the wireless communication device is temporarily busy, and - providing an indicator to a session control node associated with the data transmission indicating that the wireless communication device cannot participate in the data transmission, thereby facilitating buffering of data transmission control information associated with the data transmission.

2. The method according to claim 1, further comprising: - aborting the escalation of the paging procedure and / or preventing one or more further paging procedures associated with one or more further data transmissions from being scheduled for the wireless communication device in response to receiving the response message.

3. The method according to claim 1 or 2, in, the response message including an indicator indicating an expected duration that the wireless communication device will be unable to participate in the data transmission, The method further comprises: - indicating the expected duration to the session control node.

4. The method according to claim 1 or 2, in, The indicator indicating that the wireless communication device is temporarily unable to participate in the data transmission indicates that the wireless communication device is temporarily busy.

5. The method according to claim 1 or 2, wherein: The paging control node is the Access and Mobility Management Function AMF.

6. A paging control node of a communication network, the paging control node comprising a control circuit and an interface, the interface being configured to interact with one or more nodes of the communication network, wherein: The control circuit is configured to: - upon detecting a data transmission for a wireless communication device, triggering a paging procedure to page said wireless communication device, - receiving a response message from the wireless communication device via the interface indicating that the wireless communication device is temporarily busy, and - providing, via the interface, to a session control node associated with the data transmission, an indicator indicating that the wireless communication device cannot participate in the data transmission, thereby facilitating buffering of data transmission control information associated with the data transmission.

7. The paging control node according to claim 6, wherein: The control circuit is configured to perform the method according to any one of claims 2 to 5.

8. A method of operating a session control node, the session control node being included in a communications network, the method comprising: - upon detecting a data transmission for wireless communication, obtaining from a paging control node an indicator indicating that the wireless communication device is temporarily busy, - in response to obtaining said indicator that said wireless communication device is temporarily busy, buffering data transmission control information for said data transmission, and - When the buffering is completed, facilitating providing the data transmission control information to the wireless communication device.

9. The method according to claim 8, in, said data transmission is an incoming call, The data transmission control information is call control information.

10. The method according to claim 8 or 9, further comprising: - obtaining from a paging control node an indicator indicating an expected duration that the wireless communication device will be unable to participate in the data transmission.

11. The method according to claim 8 or 9, further comprising: - marking the data transmission control information as buffered.

12. The method according to claim 9, further comprising: - monitoring discard events while buffering the data transmission control information, - when the discarding event is detected based on the monitoring, discarding the data transmission control information.

13. The method according to claim 12, in, The drop event is at least one of a timeout in which no triggered response is received from the wireless communication device and a release indication is received from an originator of the incoming call.

14. The method according to claim 8 or 9, in, The data transmission control information is provided to the wireless communication device in response to a corresponding request from the wireless communication device.

15. A session control node of a communication network, the session control node comprising control circuitry and an interface configured to interact with one or more nodes of the communication network, wherein: The control circuit is configured to: - upon detecting a data transmission for a wireless communication device, obtaining from a paging control node via the interface an indicator indicating that the wireless communication device is temporarily busy, - in response to obtaining the indicator indicating that the wireless communication device is temporarily busy, buffering data transmission control information for the data transmission, and - When said buffering is completed, facilitating providing said data transmission control information to said wireless communication device via said interface.

Images