Wireless communication device, network node and operation method

Abstract

The present application relates to a wireless communication device, a network node and an operation method. A method of operating a wireless communication device (101), the wireless communication device comprising a wireless interface (1015) having the capability of using a first identifier (451) and a second identifier (452), the method comprising the steps of: determining a timing offset between a first timing of a first paging opportunity (396, 396-1) of a first network (100, 100-1) associated with the first identifier (451) and a second timing of a second paging opportunity (396, 396-2) of a second network (100, 100-2) associated with the second identifier (452); and sending at least one request control message (3002) to at least one of the first network (100, 100-1) or the second network (100, 100-2) based on the timing offset (780, 780-1) to request timing coordination of paging from the first network (100, 100-2) and paging from the second network (100, 100-2).

Description

Technical Field

[0001] Various examples of the present invention generally relate to paging a wireless communication device capable of connecting to at least one communication network using multiple identities. Various examples specifically relate to coordinating paging in the time domain. Background Art

[0002] Mobile communications using wireless communication devices are widespread. Some wireless communication devices (user equipment UE) can be connected to at least one communication network using multiple identities. Such UEs may, for example, have multiple user identity modules (SIMs), such as universal SIMs (USIMs). Therefore, sometimes, these UEs that can be connected to at least one communication network using multiple identities are referred to as multi-SIM UEs. In some implementations, the SIM includes both hardware and software (user subscriber identity). A universal integrated circuit card (UICC) includes hardware (e.g., a chip card) and a USIM as software representing a user identity module. The UICC may include multiple USIMs. The USIM may also be stored on various hardware such as an embedded trusted platform or an eSIM.

[0003] A multi-SIM UE may typically operate in different modes towards different networks using multiple identities. It may happen that a multi-SIM UE operates in idle mode towards multiple networks. In idle mode, the multi-SIM UE is configured to monitor paging signals from multiple networks at corresponding paging occasions (PO). The timing of the PO typically depends on the identity used to register at the corresponding network.

[0004] It has been observed that the power consumption of a Multi-SIM UE operating in idle mode towards multiple networks can be significant. Since idle mode is usually enabled to reduce power consumption, this can cause significant disadvantages. Summary of the invention

[0005] Therefore, there is a need for advanced techniques for operating a Multi-SIM UE in idle mode towards multiple networks. In particular, there is a need for techniques that facilitate low power consumption at a Multi-SIM UE.

[0006] According to various examples, techniques for coordinating paging in a multi-SIM UE having multiple subscriptions associated with multiple identities are provided. The multi-SIM UE may request the network (NW) to move or align the POs of the multiple identities in the time domain to overlap or nearly overlap in the time domain. If the request is approved by the NW, the multi-SIM UE may save power by reducing the period when it will monitor for paging signals; moreover, the multi-SIM UE may need to less frequently transition the wireless interface from an inactive state to an active state (wake-up) required to monitor for paging signals. The multi-SIM UE may monitor paging signals from different NWs in a coordinated manner, for example, contemporaneously or with a well-defined, relatively short timing offset.

[0007] A method for operating a UE including a wireless interface is provided. The wireless interface has the ability to use a first identifier and a second identifier. The method includes the step of determining a timing offset. The timing offset is between a first timing and a second timing. The first timing is the timing of a first paging occasion of a first network and is associated with the first identifier. The second timing is the timing of a second paging occasion of a second network and is associated with the second identifier. The method also includes the following steps: based on the timing offset, sending at least one request control message to at least one of the first network or the second network. Thereby, timing coordination of paging from the first network and the second network is requested.

[0008] A computer program or computer program product is provided, which includes a program code. The program code can be executed by at least one processor. Executing the program code can cause the at least one processor to perform a method of operating a UE including a wireless interface. The wireless interface has the ability to use a first identifier and a second identifier. The method includes the step of determining a timing offset. The timing offset is between the first timing and the second timing. The first timing is the timing of a first paging occasion of the first network and is associated with the first identifier. The second timing is the timing of a second paging occasion of the second network and is associated with the second identifier. The method also includes the following steps: based on the timing offset, sending at least one request control message to at least one of the first network or the second network. Thereby, the timing coordination of paging from the first network and the second network is requested.

[0009] The UE includes a wireless interface. The wireless interface has the ability to use a first identifier and a second identifier. The UE also includes a control circuit. The control circuit is configured to determine a timing offset. The timing offset is between a first timing and a second timing. The first timing is a timing of a first paging occasion of a first network and is associated with the first identifier. The second timing is a timing of a second paging occasion of a second network and is associated with the second identifier. The control circuit is also configured to send at least one request control message based on the timing offset. The at least one request control message is sent to the first network and / or the second network. Thus, timing coordination of paging from the first network and the second network is requested.

[0010] A method for operating a network node of a second network is provided. The method comprises the following steps: receiving at least one request control message from a UE. Thereby, coordination of paging from a first network and a second network is requested. The at least one request control message is associated with a timing offset between a first timing and a second timing. The first timing is the timing of a first paging occasion of the first network and is associated with a first identifier of the UE. The second timing is the timing of a second paging occasion of the second network and is associated with a second identifier of the UE. The method further comprises the following steps: selectively sending at least one response control message associated with the at least one request control message to the UE. The at least one response control message permits another timing of other paging occasions of the second network. The other timing is coordinated with the first timing.

[0011] A computer program or computer program product is provided, which includes a program code. The program code can be executed by at least one processor. Executing the program code causes the at least one processor to perform a method for operating a network node of a second network. The method includes the following steps: receiving at least one request control message from a UE. Thus, coordination of paging from a first network and a second network is requested. The at least one request control message is associated with a timing offset between a first timing and a second timing. The first timing is the timing of a first paging occasion of the first network and is associated with a first identifier of the UE. The second timing is the timing of a second paging occasion of the second network and is associated with a second identifier of the UE. The method also includes the following steps: selectively sending at least one response control message associated with the at least one request control message to the UE. The at least one response control message permits another timing of other paging occasions of the second network. The other timing is coordinated with the first timing.

[0012] A network node of a second network is provided, the network node comprising a control circuit. The control circuit is configured to receive at least one request control message from a UE. Thus, coordination of paging from a first network and a second network is requested. The at least one request control message is associated with a timing offset, i.e., a timing offset between a first timing of a first paging occasion of the first network associated with a first identifier of the UE and a second timing of a second paging occasion of the second network associated with a second identifier of the UE. The control circuit is also configured to selectively send at least one response control message. The at least one response control message is associated with the at least one request control message. The at least one response control message is selectively sent to the UE. The at least one response control message permits another timing of other paging occasions of the second network. The other timing is coordinated with the first timing.

[0013] A method for operating a UE including a wireless interface is provided. The wireless interface has the capability of using a first identifier and a second identifier. The method comprises the following steps: determining a timing offset between a first timing of a first ON duration of a first discontinuous reception (DRX) cycle of a first NW associated with the first identifier and a second timing of a second ON duration of a second DRX cycle of a second NW associated with the second identifier. Based on the timing offset, at least one request control message is sent to at least one of the first NW or the second NW. Thereby, timing coordination of the DRX cycles of the first NW and the second NW is requested.

[0014] It goes without saying that the features mentioned above and those still to be explained below can be used not only in the respective combination indicated but also in other combinations or in isolation, without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A cellular NW to which a multi-SIM UE may connect according to various examples is schematically illustrated.

[0016] Figure 2 Schematically illustrating the time dependency of the power consumption of a Multi-SIM UE when switching a radio interface from an inactive state to an active state according to various examples.

[0017] Figure 3 Schematically illustrating the time dependency of the power consumption of a Multi-SIM UE when switching a radio interface from an inactive state to an active state according to various examples.

[0018] Figure 4 A multi-SIM UE connectable to multiple NWs according to various examples is schematically illustrated.

[0019] Figure 5 POs defined in a protocol time base according to various examples are schematically illustrated.

[0020] Figure 6 The timing offsets between POs determined based on multiple identities of a multi-SIM UE according to various examples are schematically illustrated.

[0021] Figure 7 The schematic diagram illustrates a number of modes in which a multi-SIM UE may operate.

[0022] Figure 8 is a schematic illustration of a base station according to various examples.

[0023] Fig. 9 is a schematic illustration of a mobility control node of a cellular NW according to various examples.

[0024] Fig.10 is a schematic illustration of a multi-SIM UE according to various examples.

[0025] Fig.11 is a flow chart of a method according to various examples.

[0026] Fig.12 Schematically illustrating the time dependency of the power consumption of a Multi-SIM UE when switching a radio interface from an inactive state to an active state according to various examples.

[0027] Fig.13 Schematically illustrating the time dependency of the power consumption of a Multi-SIM UE when switching a radio interface from an inactive state to an active state according to various examples.

[0028] Fig.14 is a signaling diagram of communication between a multi-SIM UE and base stations of multiple NWs according to various examples.

[0029] Fig.15 is a flow chart of a method according to various examples.

[0030] Fig.16 is a flow chart of a method according to various examples. DETAILED DESCRIPTION

[0031] 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 cover what is shown and described herein. Although specific labels can be assigned to the various circuits or other electrical devices disclosed, such labels are not intended to limit the scope of operation of circuits and other electrical devices. Such circuits and other electrical devices can be combined and / or separated from each other in any manner based on the specific type of desired electrical implementation. It is 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, random access memory (RAM)), read-only memories (ROMs), erasable programmable read-only memories (EPROMs), electrically erasable programmable read-only memories (EEPROMs) or other suitable variants thereof, and software that cooperates with each other to perform the operations disclosed herein. In addition, any one or more of the electrical devices in the electrical device can be configured to execute a program code specifically implemented in a non-temporary computer-readable medium, which is programmed to execute any number of functions disclosed.

[0032] Below, with reference to the accompanying drawings, embodiments of the present invention are described in detail. It is to be understood that the following description of the embodiments is not to be viewed in a restrictive sense. The scope of the present invention is not intended to be limited by the embodiments described below or by the accompanying drawings, which are to be regarded as illustrative only.

[0033] The accompanying drawings are to be considered as schematic representations, and the elements illustrated in the drawings need not be shown in scale. On the contrary, different elements are represented so that their functions and general purposes are 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 drawings or described herein may also be achieved by indirect connection or coupling. The coupling between components may also be established by wireless connection. The functional blocks may be implemented by hardware, firmware, software or a combination of these.

[0034] Various aspects relate to a communication system. For example, the communication system may be implemented by a UE and an access node of a communication NW. For example, the access node may be implemented by a base station (BS) of a cellular NW. In the following, for simplicity, various examples will be described in conjunction with the implementation of a communication system of a UE that can be connected to a cellular NW. However, similar techniques can be easily used for other kinds and types of communication systems.

[0035] The communication system may include a wireless link between a UE and a BS. A downlink (DL) signal may be transmitted by the BS and received by the UE. An uplink (UL) signal may be transmitted by the UE and received by the BS.

[0036] Various examples described herein relate to a UE being able to connect to at least one cellular NW using two or more identities of the UE.

[0037] As usual, the term UE identity used in this article may refer to an identity associated with a user associated with the UE, that is, a user identity. The identity may include a temporary identity assigned to the UE. For example, such a UE that can be connected to at least one cellular NW using two or more identities may include multiple SIM chip cards or embedded SIMs. In the following, such a UE that can be connected to the at least one peak NW using multiple identities is referred to as a multi-SIM UE. Different identities of multi-SIM UEs are usually associated with different subscriptions at the corresponding cellular NW. Such a subscription is associated with a unique identity (e.g., an international mobile subscriber identity (IMSI)) and a unique service agreement. For example, policies and billing and / or traffic shaping for phone calls, short message services, and packet data or other services may depend on the corresponding service model. As usual, if a multi-SIM UE is connected to at least one cellular NW using a first identity, a corresponding IP address, a unique mobile station international subscriber telephone number (MSISDN), and a unique data connection to the cellular NW may be provided. If a multi-SIM UE is connected to the same at least one cellular NW using a second identity different from the first identity, these parameters may be different. Therefore, it can be said that from the NW perspective, the Multi-SIM UE will be considered as two independent UEs.

[0038] As usual, multi-SIM UEs can use their multiple identities to connect to the same cellular NW or different cellular NWs. For example, this document describes some scenarios in which multi-SIM UEs are connected to multiple cellular NWs; however, the technology can also be applied to scenarios in which multi-SIM UEs use multiple identities to connect to the same cellular NW.

[0039] As usual, it is optional for a multi-SIM UE to have a communication interface with dual transmission capabilities. In particular, a multi-SIM UE that does not have dual transmission and / or reception (transmission) capabilities is sometimes referred to as a "single radio". The transmission of a signal may include sending a signal and / or receiving a signal. Then, in order to be able to communicate with multiple cellular NWs, time multiplexing is adopted. A multi-SIM UE with dual transmission capabilities is sometimes referred to as a "multi-radio". Such a multi-radio multi-SIM UE can, for example, perform simultaneous transmission and / or reception via multiple frequencies. Therefore, frequency multiplexing is possible. The technology described herein is generally applicable to both, i.e., a single-radio multi-SIM UE and a multi-radio multi-SIM UE.

[0040] Various techniques are based on the discovery that operation of a multi-SIM UE using multiple identities may have an impact on paging.According to various examples described herein, optimized paging may be achieved for a multi-SIM UE.

[0041] According to various techniques, timing coordination of paging from multiple cellular NWs may be achieved. To this end, a multi-SIM UE may determine a timing offset between (i) a first timing of a first PO of a first cellular NW associated with a first identity and (ii) a second timing of a second PO of a second cellular NW associated with a second identity.

[0042] As usual, the timing offset may be zero or may be greater than zero, for example, greater than a predetermined lower threshold. In the latter case, the first PO and the second PO may not overlap in the time domain, but may be offset from each other.

[0043] Then, based on the timing offset, at least one request control message may be sent to the first cellular NW and / or the second cellular NW to request timing coordination.

[0044] Upon receiving the at least one request control message, the NW nodes of the first cellular NW and / or the second cellular NW (e.g., the BS or the mobility control node of the core of the corresponding cellular NW) may or may not permit another timing of other POs of the second cellular NW. Then, the multi-SIM UE may monitor the paging signal from the second cellular NW at other POs according to another timing (rather than at the second PO according to the second timing). Therefore, the first timing of the first PO and the other timing of the other POs are coordinated in the time domain.

[0045] As usual, timing coordination can result in a reduction in timing offset or an increase in timing offset. In other words, the size of another timing offset between a first timing of a first PO and another timing of another PO can be formed to be smaller or larger than the timing offset between the first timing and the second timing.

[0046] The various techniques described herein are based on the finding that when operating a multi-SIM UE, in particular in an idle mode including paging, power consumption will be affected when using the reference techniques. By using the above techniques, i.e. by coordinating the paging of multiple cellular NWs, it becomes possible to reduce the energy consumption at the UE. For example, due to the coordination of paging, the duration for which the multi-SIM UE is required to operate the modem of its wireless interface in an active state can be reduced. Alternatively or in addition, it may be less often necessary to convert the modem from an inactive state to an active state; such powering up of the modem is typically associated with significant energy consumption. Then, by requiring a transition from an inactive state to an active state less often, energy consumption can be reduced. In particular, this can be achieved when the further timing offset is less than the timing offset between the first timing of the first PO and the second timing of the second PO.

[0047] The various techniques described herein are based on the discovery that when operating a multi-SIM UE, in particular in an idle mode including paging, hardware capabilities may impose constraints on paging. In particular, a situation may occur in which a first PO of a first cellular NW and a second PO of a second cellular NW overlap. For example, if a single-radio multi-SIM UE is used, it may be necessary to adjust the frequency of a radio frequency filter of a modem of a wireless interface of the UE between a first timing of a first PO and a second timing of a second PO. Typically, the tuning rate of such a radio frequency filter is limited. Thus, a complete or partial overlap between the first timing and the second timing limits the ability of the multi-SIM UE to monitor paging signals from the first cellular NW and paging signals from the second cellular NW. Such limitations imposed by the hardware capabilities of the multi-SIM UE can be mitigated by requesting paging coordination. In particular, the limitation of the hardware capabilities can be mitigated when another timing offset is greater than the timing offset between the first timing of the first PO and the second timing of the second PO. Then, sufficient time can be provided to tune the radio frequency filter between the first timing of the first PO and another timing of other POs.

[0048] In the following, various techniques are described in the context of a scenario in which a UE requests timing coordination that results in a decrease in the timing offset between the corresponding POs of the first cellular NW and the second cellular NW. However, similar techniques can also be applied to a scenario in which a UE requests timing coordination that results in an increase in the timing offset between the corresponding POs of the first cellular NW and the second cellular NW.

[0049] According to various examples, POs of NWs operated by different operators are coordinated for multi-SIM UEs. The reason for coordinating POs in the time domain is generally power saving. In idle mode, when a paging indication and / or a paging message (paging signal) is monitored, the UE must start a wireless interface including a wireless modem to receive the paging signal; this corresponds to a transition of the wireless interface from an inactive state to an active state, i.e., wake-up. Sometimes, the inactive state is also referred to as a low-power state or a sleep state. The active state is sometimes referred to as a high-power state. Wake-up may take a significant time and consume power, in most cases more than the power consumed by the active duration for receiving the paging signal. In addition, power consumption increases with the number of POs that the UE monitors according to the period of the DRX cycle, i.e., the shorter the DRX cycle, the more frequently the UE must wake up. Therefore, instead of having multiple different and parallel DRX cycles to follow, the activity of the modem is reduced in the case where the UE only needs to convert to an active state once per DRX cycle (the shortest DRX cycle of the connected NW).

[0050] In order to achieve such a reduction in the number of wake-ups for periods of multiple and overlapping DRX cycles, the following technique may be employed: When a multi-SIM UE (having a first identity and a second identity) registers to a cell belonging to a second NW (e.g., a second public land mobile NW, PLMN), the timing of the PO of the cell is based on the corresponding second identity of the UE used at the time of registration, e.g., an S-temporary mobile subscriber identity (S-TMSI). For the case where the POs of the first and second identities of the multi-SIM UE (determined based on the first and second identities) do not overlap in the time domain (because the identities are different and / or the protocol time bases such as subframe numbers may be different), the UE determines a timing offset between a first timing of a first PO of the first NW and a second timing of a second PO of the second NW. If there is a significant timing offset (e.g., greater than a predetermined threshold), the UE may prefer to adjust the paging timing of the second NW. Therefore, the multi-SIM UE may report the timing offset or preferred timing to a radio access NW (RAN) of the second NW. The corresponding BS of the RAN may report the timing offset to a core network (CN) entity of the second NW. Alternatively or additionally, the UE may report the timing offset or preferred timing directly to the CN of the second NW.The transmission of such a reporting control message may be done during the connection procedure of the second NW.

[0051] The timing offset or preferred timing may be reported using the protocol time base of the second NW (e.g., a sequence number or count of frames or subframes). Alternatively or in addition, the timing offset or preferred timing may be reported as an "alternative" another identifier that may be used to calculate an "alternative" another timing of other POs of the second NW. Alternatively or in addition, the timing offset or preferred timing may be reported as a time difference (e.g., in milliseconds) under a global time reference.

[0052] When the NW node of the second NW has received the timing offset or preferred timing or other corresponding value, it can signal to the UE the adjusted another timing of other POs to be used by the second NW, or simply confirm the suggested another timing of other POs that has been indicated by the UE.

[0053] The other POs are coordinated with the first PO of the first NW. As a rule, another timing offset between another timing of the other POs and the first timing of the first PO may be smaller than the timing offset between the second timing of the second PO and the first timing of the first PO. For example, the other POs may completely or partially overlap with the first PO in the time domain. As long as the distance between the first PO and the other POs is shorter than the wake-up time in the UE, the power consumption of the UE is generally improved. Typically, the wake-up time may depend on the UE hardware capabilities and may be as long as tens of milliseconds or even seconds. Guidance is usually done step by step, so some parts are guided faster than other parts of the modem, and it is not necessary to guide every part to monitor the paging signal.

[0054] As will be appreciated, wake-up times in the order of a few milliseconds or tens of milliseconds or even up to hundreds of milliseconds may be significant if compared to a typical period of a DRX cycle, which may be in the order of seconds, for example. For example, the wake-up time may be in the order of 1% to 10% of the period of a DRX cycle. This means that if there are multiple POs to be monitored for multiple identities, then the time in terms of the period of the DRX cycle required to enable the modem may be significant.

[0055] The multi-SIM UE may then monitor other POs for paging signals from the second NW. The multi-SIM UE may monitor the first PO for paging signals from the first NW. This enables the paging signals from the first NW and the second NW to be received in overlapping frames or adjacent frames. It may be beneficial for power consumption that all paging indicators from the first NW and the second NW may be received in the same subframe.

[0056] The number of simultaneous paging signals on different frequency bands etc. that a UE can read in the same subframe is sometimes limited by the hardware capabilities of the UE. Therefore, the UE can indicate another timing that is preferred so that the number of paging signals that collide in time on different carrier frequencies is less than or equal to the number of paging signals that the UE can read / receive simultaneously given its hardware capabilities (e.g., whether it has dual transmission capabilities or how many transmit / receive chains are available). This can be achieved by signaling a lower timing tolerance.

[0057] In the case where the UE cannot receive paging signals on multiple frequencies at the same time (for example, because the UE does not have dual transmission capability or the two receivers do not support certain frequency combinations, for example, due to crosstalk limitations or shared radio frequency parts), the UE requests preferred timing so that the first timing of the first PO and the other timings of the other POs are close to each other in the time domain, but do not overlap. This is still beneficial for power consumption as long as the distance between the first PO and the other POs is less than the wake-up time of the UE.

[0058] In most cases, the Multi-SIM UE is not actually paged at the PO, and thus, it may switch the radio interface to an inactive state until the next ON duration of the DRX cycle. There is a risk that the Multi-SIM UE is paged by two NWs in the same period of the DRX cycle: the UE may then start data connection establishment in several NWs simultaneously in the same frame or in subsequent frames. If the UE cannot respond to the paging signals simultaneously due to hardware capability limitations of the UE, the UE may choose which paging signal to respond to. In case it is known that some of the services are delay tolerant, it may be feasible to respond immediately to emergency services, while waiting and delaying the response to the delay tolerant services.

[0059] Figure 1 A cellular NW 100 is schematically illustrated. Figure 1 The example of illustrative embodiment illustrates a cellular NW 100 according to the 3GPP 5G architecture. The details of the 3GPP 5G architecture are described in 3GPP TS23.501, version 15.3.0 (2017-09). Figure 1 The following and other parts of the description illustrate the technology in the 3GPP 5G framework of cellular NW, but similar technology can be easily applied to other communication protocols. Examples include 3GPP LTE 4G (e.g., in MTC or NB-IOT framework) and even non-cellular wireless systems (e.g., IEEE Wi-Fi technology).

[0060] exist Figure 1 In the scenario 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; etc.

[0061] UE 101 is a multi-SIM UE 101: the UE 101 is able to connect to a cellular NW using two identities 451, 452 (in Figure 1 In the example, only a single cellular NW is illustrated. The identifiers 451 and 452 may be static or temporary, for example, a temporary mobile subscriber 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 a network via one or more BSs 112 (for simplicity, Figure 1 The RAN 111 formed of a cellular NW 100 (only a single BS 112 is illustrated in the figure) is connected to a core NW (CN) 115 of the cellular NW 100. A wireless link 114 is established between the RAN 111 and the UE 101 (specifically, between one or more BSs in the BS 112 of the RAN 111 and the UE 101).

[0063] The wireless link 114 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 time-frequency resource components of the time-frequency resource grid. Thus, for example, a protocol time base is defined according to the duration of frames and subframes comprising a plurality of symbols and the start and stop positions of frames and subframes. Different time-frequency resource components 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); Random Access Channel; etc.

[0064] The wireless links 114 of the cellular NWs to which the UE 101 connects using its multiple identities may be different from each other, for example, 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] CN 115 includes a user plane (UP) 191 and a control plane (CP) 192. Application data is usually routed via UP 191. For this purpose, a UP function (UPF) 121 is provided. UPF 121 can implement a router function. Application data can pass through one or more UPFs 121. Figure 1 In the scenario of , UPF 121 acts as a gateway towards data NW 180 (eg, the Internet or a local NW). Application data may be transmitted between UE 101 and one or more servers on data NW 180.

[0066] The cellular NW 100 also includes a mobility control node, which is implemented here 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; a NW slice selection function (NSSF) 134; an authentication server function (AUSF) 136; and a unified data management (UDM) 137. Figure 1 Protocol reference points N1 to N22 between these nodes are also illustrated.

[0068] AMF 131 provides one or more of the following functions: connection management, sometimes also referred to as registration management; NAS termination for communications between CN 115 and UE 101; connection management; reachability management; mobility management; access authentication; and connection authorization. For example, if the corresponding UE 101 is operating in idle mode, AMF 131 controls the paging initiated by the CN to UE 101. AMF 131 can trigger the transmission of a paging signal for UE 101; this can be aligned in time with the PO. After the UE registers with the NW, AMF 131 creates a UE context 459 and maintains the UE context, at least as long as the UE 101 is registered with the NW. UE context 459 can save one or more identities of UE 101, for example, a temporary identity used for paging as described herein. AMF 131 also provides 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 save the timing offsets between the POs of the multiple NWs to which the UE is connected. The UE context may also save the timing for paging the UE, for example, in milliseconds.

[0069] If the corresponding UE 101 is operating in connected mode, the SMF 132 establishes a data connection 189. The data connection 189 is characterized by the UE subscription information hosted by the UDM 137. In order to track the current mode of the UE 101, the AMF 131 sets the UE 101 to CM-CONNECTED or CM-IDLE. During CM-CONNECTED, a non-access stratum (NAS) connection is maintained between the UE 101 and the AMF 131. The NAS connection implements an example of a mobile control connection. The NAS connection can be established in response to a 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 bearer establishment of UP bearers between RAN 111 and UPF 121; selection and control of UPF; configuration of service guidance; roaming functions; termination of at least part of NAS messages; etc. In this way, both AMF 131 and SMF 132 implement CP mobility management required to support mobile UEs.

[0071] A data connection 189 is established between the UE 101 via the RAN 111 and the UP 191 of the CN 115 and towards the DN 180. For example, a connection to the Internet or another packet data NW may be established. In order to establish the data connection 189, i.e., to connect to the cellular NW 100, the corresponding UE 101 may, for example, perform a random access (RACH) procedure in response to receiving a paging signal. The server of the DN 180 may host a service that transmits payload data via the data connection 189. The data connection 189 may include one or more bearers, such as a dedicated bearer or a default bearer. The data connection 189 may be defined at the RRC layer (e.g., typically layer 3 in the layer 2 OSI model).

[0072] Next, combine Figure 2 and Figure 3 To describe the details about paging.

[0073] Figure 2 and Figure 3 Schematically illustrates various aspects of the operation of UE 101 according to various examples. In particular, Figure 2 and Figure 3 Various aspects of power consumption over time with respect to a radio interface of the UE 101 according to various examples are schematically illustrated. Figure 2 and Figure 3 The power consumption associated with the activities of the UE 101, in particular, paging-related activities, is illustrated.

[0074] BS 112 may send a paging signal. As usual, a paging signal is used when UE 101 is operating in idle mode 302; the paging signal may trigger a transition from idle mode 302 to connected mode 301. A data connection 189 may be established upon receipt of a paging signal. Paging signals may also be used in inactive mode. In inactive mode, paging may be triggered by the RAN; when in idle mode 302, paging is triggered by the CN.

[0075] In detail, the idle mode 302 is associated with a DRX cycle 395. Here, the UE 101 periodically switches the modem of its radio interface to an inactive state 391 (during Figure 21801 and 1804) with active state 392 (during Figure 2 and Figure 3 During the period 1803; note that Figure 2 and Figure 3 395). The periods 1801 and 1804 correspond to the OFF duration of the DRX cycle 395; the period 1803 corresponds to the ON duration of the DRX cycle 395. The period 1803 of the active state 392 is time-aligned with the PO 396, during which the cellular NW 100 can send a paging signal.

[0076] The timing of the PO is given by (i) the system frame number (SFN) and (ii) the subframe within that frame and (iii) the UE_ID obtained from the corresponding identity 451, 452 of the UE 101 (for the example of 3GPP NR).

[0077] When the modem is operating in the inactive state 391, the UE 101 cannot receive paging signals; for example, the analog front end and / or the digital front end of the modem can be powered off. For example, the amplifier and the analog-to-digital converter can be turned off. For example, the decoding digital block can be turned off. When power can be saved, the UE hardware enters the inactive state 391. When the UE hardware is in the inactive state 391, one or more clocks can be turned off, all radio blocks and most modem blocks can be turned off, and only minimal activity using a low-frequency (RTC) clock can be maintained to start the platform at the time of the next PO 396. Therefore, the inactive state is associated with relatively small power consumption.

[0078] When operating the modem in active state 392, UE 101 may monitor for paging signals. Various hardware components of the modem of the wireless interface are powered on and operating. For example, UE 101 may perform blind decoding of the PDCCH to detect a paging indicator. Accordingly, active state 392 is associated with relatively high power consumption.

[0079] like Figure 2 As illustrated, the period 1802 (wake-up time) required to convert the UE 101 from the inactive state 391 to the active state 392 is significant. This conversion may require (re)adjustment of frequency and timing, and the need to start the modem to be able to receive paging signals. This takes a relatively long time. Therefore, the power consumption for wake-up is significant. In the following, a strategy is described that promotes reducing the overall power consumption of the UE 101 by reducing the number of transitions from the inactive state 391 to the active state 392, in particular by reducing the duty cycle (i.e., the duration of the periodic active state relative to the DRX cycle).

[0080] For example, when the NW 100 intends to establish a data connection 189 or a system information update or for sending a public warning message, the UE is paged; the reason may include a change in the cell configuration due to buffered DL data. The UE 101 typically checks a specific subframe in the frame structure once in each period of the DRX cycle (usually 1.28s or 2.56s), reads and blindly decodes the PDCCH to check whether any paging indicator is sent to any UE in the paging group in the subframe.

[0081] exist Figure 2 In the scenario of , UE 101 does not receive a paging signal during period 1803; therefore, it switches back to inactive state 391 during period 1804. The process is repeated after period 399 of DRX cycle 395 (eg, Figure 2 Once the paging indicator is detected, the UE 101 then reads the paging message on the paging channel (PCH) - this is done in Figure 3 The paging message is shown in the time period 1811. Based on the paging message, a data connection can be established.

[0082] The paged UE is paged for a predetermined time (e.g., a gap duration 1812 until a period 1813 in which a random access procedure is performed, such as Figure 3 As shown), a random access procedure is started, and then UE 101 enters connected mode 301.

[0083] Before establishing the data connection 189, the UE 101 has limited information about the services (eg, incoming calls, other downlink application traffic, or even information about system information updates or public warning messages PWS).

[0084] The UE monitors the paging indicator and paging message (paging signal) in the PO 396 (for each identity 451, 452) of each period of the DRX cycle. There is no paging message in most POs, but if there is a DL message to the UE, the UE 101 must monitor the radio link 114 to prepare.

[0085] The timing of PO 396 in 3GPP NR 5G is defined in 3GPP Technical Specification (TS) 38.304 V15.4.0, chapter 7, "Paging". In 3GPP LTE 4G, these timings are defined in a similar manner to those defined in 3GPP TS 36.304 V15.4.0, chapter 7 "Paging".

[0086] The SFN of a frame including PO (paging frame, PF) is determined by the following formula:

[0087] (SFN+PF_offset) mod T = (T div N) * (UE_ID mod N) (Rule 1)

[0088] Where UE_ID is given by

[0089] S-TMSI mod 1024, (Rule 2)

[0090] Furthermore, in Rule 1, T is the periodicity of the DRX cycle, and PF_offset and N are obtained from the broadcast parameters of the corresponding cell.

[0091] Thus, the timing of the PO is defined by the UE identity 451, ie via the UE_ID and the S-TMSI.UEs with different identities will typically page in different PFs and with different POs unless the UE_ID mod N is the same for different identities.

[0092] Figure 4 Schematically illustrates various aspects of the plurality of identifiers 451, 452. Figure 2 In the scenario, two cellular NWs 100-1 and 100-2 are provided. Each of the cellular NWs 100-1 and 100-2 can be configured according to Figure 1 UE 101 is configured to communicate with cellular NW 100-1 via a first wireless link 114-1 using an identifier 451; and is configured to communicate with cellular NW 100-2 via a second wireless link 114-2 using an identifier 452. Each cellular NW 100-1, 100-2 may store a corresponding UE context 459 associated with the corresponding identifier 451, 452.

[0093] There are various options available to achieve or not achieve time domain synchronization between the cellular NWs 100-1, 100-2. They are described in Table 1.

[0094]

[0095] Table 1: Synchronization options for multiple cellular NWs

[0096] Figure 5 Various aspects regarding the transmission protocol implemented over the wireless link 114 are schematically illustrated. Figure 5 A transmission frame 701 is schematically illustrated. Figure 5 Subframes 702 are also schematically illustrated. Each transmission frame 701 includes multiple subframes 702, for example, Figure 5 Ten subframes of the scene.

[0097] exist Figure 5 In the example of FIG. 3 , the periodicity 399 of the DRX cycle 395 is 32 frames 701 corresponding to 320 milliseconds. A PO 396 is defined for a specific subframe 702 of the corresponding paging frame 701 (in Figure 5 According to rules 1 and 2, different identifiers 751, 752 may be associated with different paging frames 701 and / or different subframes 702. A timing offset between POs may be generated.

[0098] Figure 6 Schematically illustrated are various aspects regarding the timing offset 780 between a plurality of POs 396-1, 396-2 associated with a plurality of identities 451, 452. In this case, the periodicity 399 of the two DRX cycles is N frames, the paging frames 701 of the identity 451 are "1", "N+1", "2N+1", etc.; the paging frames 701 of the identity 452 are "8", "N+8", etc. Moreover, the frame offset between the protocol time bases of the NWs 100-1, 100-2 (see synchronization option II in Table 1) is 7 frames. Therefore, the corresponding timing offset 780 between the POs 396-1, 396-2 is 2 frames (e.g., corresponding to a 20ms duration).

[0099] Figure 7 Aspects are illustrated regarding different modes 301 to 303 that the UE 101 may operate in. Example implementations of the operating modes 301 to 303 are described, for example, in 3GPP TS 38.300 (eg, version 15.0.0).

[0100] Before initially connecting to the NW 100-1, 100-2, a PLMN search mode 303 is performed. Here, multiple candidate frequencies are searched, and the UE 101 attempts to acquire a synchronization signal to obtain a time reference for the corresponding cellular NW 100-1, 100-2. At this time, the AMF 131 may not save the context of the UE 101. Once the time reference is obtained, the identity of the cellular NW 100-1, 100-2 may be checked in the broadcast information block, for example. Then, a data connection 189 may be established by performing a random access procedure. This triggers a transition to the connected mode 301.

[0101] During connected mode 301 (see Figure 3 ; right side), establish a data connection 189. For example, a default bearer and optionally one or more dedicated bearers may be established between the UE 101 and the cellular NW 100. The wireless interface of the UE 101 may continue to operate in an active state, or a DRX cycle may be implemented.

[0102] To achieve power reduction, an idle mode 302 may be implemented (see Figure 2and Figure 3 ). Here, the UE 101 operates according to the DRX cycle 395. The wireless interface 1011 of the UE 101 may be switched to the active state 391. The data connection 189 is released. A paging signal is sent to switch the UE 101 back to the connected mode 301.

[0103] Figure 8 The BS 112 of the RAN 111 is schematically illustrated.

[0104] BS 112 includes interface 1125. For example, interface 1125 may include an analog front end and a digital front end. BS 112 may communicate with UE 101 via interface 1125 over wireless link 114. Interface 1125 may also be used to signal toward CN 115.

[0105] The BS 112 also includes a control circuit 1122 implemented, for example, by means of one or more processors and / or software. For example, a program code to be executed by the control circuit 1122 may be stored in a non-volatile memory 1123. In various examples disclosed herein, the control circuit 1122 may implement various functions by executing the program code, such as: obtaining a request for coordinated paging from the multi-SIM UE 101, for example, via the interface 1125; coordinating paging with another NW; implementing paging, for example, by sending a paging indicator and / or a paging message (paging signal) to the multi-SIM UE 101. As usual, the paging message may resolve ambiguity regarding multiple UEs addressed by the same paging indicator.

[0106] Fig. 9 The AMF 131 is schematically illustrated.

[0107] AMF 131 includes an interface 1315. For example, interface 1315 may be used to communicate with other core NW nodes or toward a radio access NW (eg, via Figure 1 N2 reference point) or to UE 101 (e.g., via Figure 1 N1 reference point) to signal.

[0108] The AMF 131 also includes a control circuit 1312 implemented, for example, by means of one or more processors and software. For example, a program code to be executed by the control circuit 1312 may be stored in a non-volatile memory 1313. In various examples disclosed herein, the control circuit 1312 may implement various functions by executing the program code, such as: obtaining a request for coordinated paging from a multi-SIM UE; coordinating paging with another NW; implementing paging, for example, by sending a command to a base station for sending a paging signal to the multi-SIM UE.

[0109] Fig.10Schematically illustrated is a multi-SIM UE 101. For example, the UE 101 may be configured to connect to cellular NWs 100, 100-1, 100-2 and communicate using corresponding identities 451, 452.

[0110] exist Figure 7 In the example of , UE 101 is a dual radio UE and includes a wireless interface 1015 with two radio modems 1018, 1019. Thus, UE 101 has dual transmission capabilities and can monitor paging signals on multiple frequencies at overlapping or partially overlapping POs, for example. Each radio modem 1018, 1019 can be configured to use a corresponding identifier 451, 452.

[0111] For example, each radio modem 1018, 1019 of the interface 1015 may include an analog front end and a digital front end. The UE 101 may transmit or receive via the radio 1018 and simultaneously transmit or receive via the radio 1019 (dual transmission capability).

[0112] The radio 1018, 1019 may typically have two clock sources. A low frequency clock with low power consumption and poorer accuracy / stability. A faster clock with higher accuracy and better stability. The latter clock is needed to decode the signal without distorting it too much, and is locked to the carrier frequency by a high frequency PLL. The digits of the modem then typically have multiple clocks for clocking the CPU and hardware accelerator memory, etc. These are products of phase locked loops, which typically utilize a slower clock source that may be such a real time clock.

[0113] Although in Fig.10 In the example of , UE 101 is illustrated as having two radio modems 1018, 1019, but in other examples, UE 101 may have only a single radio modem. Thus, multi-SIM UE 101 does not have dual transmission capability. It may employ time duplexing to communicate with multiple NWs 100-1, 100-2 using multiple identities 451, 452.

[0114] UE 101 also includes a control circuit 1012 implemented, for example, by means of one or more processors and software. For example, a program code to be executed by the control circuit 1012 may be stored in a non-volatile memory 1013. In various examples disclosed herein, the control circuit 1012 may implement various functions by executing the program code, such as: communicating with a first NW via one or more first frequencies; communicating with a second NW via one or more second frequencies; determining a timing offset between timings of POs associated with multiple identities of a multi-SIM UE; requesting coordination of paging associated with multiple identities of at least one NW; monitoring paging signals, for example, based on coordinated paging; etc.

[0115] Fig.11 is a flow chart of a method according to various examples. For example, a UE (e.g., Fig.10 The illustrated multi-SIM UE 101) performs Fig.11 method.

[0116] At block 2001, a timing offset is determined. The timing offset is between a first timing of a first PO of a first cellular NW associated with a first identity of a multi-SIM UE and a second timing of a second PO of a second cellular NW associated with a second identity of the multi-SIM UE. Figure 6 An example timing offset 780 of a first PO 396-1 of a first cellular NW 100-1 and a second PO 396-2 of a second cellular NW 100-2 is illustrated.

[0117] Next, at block 2002, the timing of the first PO and the second PO are coordinated.

[0118] This may include the multi-SIM UE requesting coordination of paging from the first cellular NW and the second cellular NW. Coordination is requested based on the timing offset determined at block 2001 .

[0119] Depending on the specific scenario, coordination may be requested to increase the timing offset or decrease the timing offset.

[0120] The multi-SIM UE may send at least one request control message indicating the request. The at least one request control message may be sent to the first cellular NW and / or the second cellular NW.

[0121] For example, the at least one request control message may indicate whether the timing offset is to be increased or decreased.

[0122] More specifically, the at least one request control message may be sent to a BS of the RAN of the first cellular NW or the second cellular NW, or to a mobility control node (such as AMF 131, see Figure 1 ), or sent to another node of CN.

[0123] Block 2002 may optionally include receiving a response from the first cellular NW and / or the second cellular NW. For example, at least one response control message may be received from the first cellular NW and / or the second cellular NW to which the at least one request control message has been sent. Here, the at least one response control message is associated with the at least one request control message previously sent.

[0124] The at least one response control message may allow or deny another timing of other POs of the second NW. The other timing of the other POs may be different from the second timing of the second PO. For example, if compared with the timing offset between the first timing of the first PO and the second timing of the second PO, the other timing may reduce the other timing offset between the first timing of the first PO and the other timing of the other POs, for example, to zero or a finite value. Alternatively or in addition, the other timing may also increase the other timing offset between the first timing and the other timing. This may depend, for example, on the corresponding preference indicated by the UE.

[0125] Then, in optional box 2003, the multi-SIM UE 101 may monitor the paging signal. In detail, the multi-SIM UE 101 may monitor the first paging signal from the first NW according to the first timing of the first PO, and monitor the second paging signal from the second NW according to another timing of other POs. If a single-radio multi-SIM UE 101 is adopted, the frequency may be switched between the first PO in a given period of the DRX cycle and the adjacent PO in other POs.

[0126] Due to the reduced further timing offset between the first timing and the further timing, the multi-SIM UE can perform a single wake-up according to the period of the DRX cycle and, in response to the single wake-up, combine monitoring of the first paging signal and monitoring of the second paging signal before transitioning back to an inactive state (if no paging signal is received). This helps to reduce power consumption,

[0127] Combination Fig.12 This finding is further illustrated.

[0128] Fig.12 Aspects regarding the timing of POs 396-1, 396-2, and 396-3 are schematically illustrated. Fig.12 The power consumption of the wireless interface 1015 of the Multi-SIM UE 101 is plotted as a function of time.

[0129] As illustrated, there is a first PO 396-1 associated with a first identifier 451 used by UE 101 to communicate with a first cellular NW 100-1. Figure 2 In a manner comparable to that described, the multi-SIM UE 101 initially operates in the inactive state 391 during a period 1821. Then, during a period 1822, the multi-SIM UE 101 switches the wireless interface from the inactive state 391 to the active state 392. During a period 1823, the multi-SIM UE 101 monitors a first paging signal from the first cellular NW 100-1, and a second paging signal from the second cellular NW 100-2. This is because another timing of another PO 396-3 of the second cellular NW 100-2 is coordinated with the first timing of the first PO 396-1 of the first cellular NW 100-1.

[0130] The first timing of the first PO 396-1 is determined based on the identification 451 (Rule 1, Rule 2) however, another timing of other POs 396-3 is obtained differently, ie not based on Rule 1 or Rule 2. This case is described below.

[0131] According to rules 1 and 2, the PO 396-2 is generated taking into account the identity 452 of the multi-SIM UE 101. Fig.12 As illustrated, there is a significant timing offset 780-1 between the timing of the first PO 396-1 and the timing of the second PO 396-2. This will force the UE 101 to transition back to the inactive state 391 and then back to the active state 392 within a single period 399 of the DRX cycle 395, as shown in FIG. Fig.12 This is associated with increased power consumption.

[0132] On the other hand, another timing offset 780-2 between the first timing of the first PO 396-1 and another timing of another PO 396-3 is smaller than the timing offset 780-1. Fig.12 As illustrated, the first PO 396-1 and the other POs 396-3 partially overlap in time. As usual, they may be completely overlapped, partially overlapped, adjacent to each other, or arranged with a time gap therebetween. Further as usual, in the case of synchronizing the cellular NWs 100-1, 100-2, the first PO 396-1 and the other POs 396-3 may be arranged in the same or adjacent subframes 702 (as described in the synchronization options I or II in Table 1 above).

[0133] As usual, another timing may be associated with another corresponding identity or paging identity of the UE (e.g., a paging temporary identity (P-TMSI)). This will be given by:

[0134] (SFN+PF_offset)mod T=(T div N)*(UE_ID'mod N) (Rule 3)

[0135] Where UE_ID' is given by

[0136] P-TMSI mod 1024, (Rule 4)

[0137] The paging identifier may have the same structure as the second identifier 452, for example, the same length, the same number space, etc. However, the paging identifier may generate another timing of another PO 396-3 that is different from the second timing of the second PO 396-2.

[0138] Coordination of a first timing of a first PO 396-1 with another timing of other POs 396-3 facilitates a single transition from the inactive state 391 to the active state 392 per period 399 of the DRX cycle 395. This reduces power consumption compared to the reference implementation illustrated by dashed lines.

[0139] Fig.12 The illustrated scenario may be particularly helpful for a multi-SIM UE that is able to monitor paging signals from multiple cellular NWs on multiple frequencies concurrently. Fig.13 Another scenario illustrated may be helpful for a single radio multi-SIM UE that cannot monitor paging signals from multiple NWs on multiple frequencies concurrently, but must use frequency switching between the first PO 396-1 and other POs 396-3 to implement a time multiplexing scenario.

[0140] Fig.13 Aspects regarding the timing of POs 396-1, 396-2, and 396-3 are schematically illustrated. Fig.13 The power consumption of the wireless interface 1015 of the Multi-SIM UE 101 is plotted as a function of time.

[0141] Fig.13 The scenario generally corresponds to Fig.12 The scene. Fig.13 In the scene, with Fig.12 Compared to the scenario of FIG. 1830 , there is a larger timing offset 780-2 between the first PO 396-1 and the other POs 396-3. This is to accommodate the frequency switching (e.g., adjusting the RF oscillator circuit) between the carrier frequencies of the two cellular NWs 100-1 and 100-2 during the period 1831, and then monitor the paging signal from the NW 100-2 during the period 1832.

[0142] Therefore, if Fig.12 and Fig.13It is appreciated that the timing offset 780-2 may be coordinated with respect to the hardware capabilities of the modem of the wireless interface 1015 of the UE 101. The hardware capabilities may be related to, for example: single radio or multi-radio UE; frequency conversion rate; dead time; energy consumption when operating in the inactive state 391; energy consumption when operating in the active state 392; energy consumption of a wake-up transition from the inactive state 391 to the active state 392; etc.

[0143] Fig.14 4 is a communication signaling diagram between a multi-SIM UE 101, a BS 112-1 of a cellular NW 100-1, and another BS 112-2 of the NW 100-2 using multiple identities 451 and 452.

[0144] Although Fig.14 Signaling between a multi-SIM UE 101 and BSs 112-1, 112-2 is illustrated, but similar techniques may be implemented for scenarios where the multi-SIM UE 101 utilizes the AMFs of multiple cellular NWs 100-1, 100-2 for signaling.

[0145] At 4001 , UE 101 acquires the timing of BS 112 - 1 of first cellular NW 100 - 1 ; for example, UE 101 may receive synchronization signal 3001 .

[0146] Similarly, at 4002, UE 101 acquires the timing of BS 112-2 of the second cellular NW 100-2.

[0147] At 4003 , the UE 101 determines a timing offset 780 - 1 between a first timing of a first PO 396 - 1 of a first cellular NW 100 - 1 given by identification 451 and a second timing of a second PO 396 - 2 of NW 100 - 2 given by identification 452 .

[0148] As usual, various scenarios for triggering the execution of 4003 (i.e., triggering the determination of the timing offset 780-1) can be envisioned. One option is to acquire the timing of the second cellular NW 100-2 at a point in time when the timing of NW 100-1 has been acquired (i.e., connecting to another NW in addition to the already existing connection). In particular, in such a scenario, a request control message may be sent to the second cellular NW 100-2 during the connection process. Alternatively or in addition, the timing offset 780-1 may be determined in response to a cell reselection (e.g., when the UE 101 reselects the cell of the second cellular NW 100-2). This depends in particular on whether there is synchronization between the multiple cells of the NW 100-2. In yet another option, the timing offset 780-1 may be determined when the accumulated timing drift between the first cellular network NW 100-1 and the second cellular NW 100-2 exceeds a threshold and / or determined according to a predetermined schedule. In the case where the first cellular NW 100-1 and the second cellular NW 100-2 are not synchronized, there may be a timing drift between them. The timing drift may accumulate over time, i.e., become larger and larger. The timing drift may be of the order of 0.2μs to 1μs per second. Therefore, the accumulated timing drift after 10,000 seconds will be 10ms, which is the duration of the frame 701 according to 3GPP 5G. The accumulated timing drift may be tracked. Once the accumulated timing drift exceeds a predetermined threshold, the re-coordination of paging may be triggered by re-determining the current timing offset 780-1. On the other hand, a predetermined schedule may be a convenient tool for simplifying the determination of the current timing offset 780-1 from time to time. In another option, the timing offset 780-1 is determined in response to a corresponding trigger message from the first cellular NW 100-1 or the second cellular NW 100-2. For example, due to UE mobility, the corresponding trigger message may be sent as part of a handover or cell reselection process.

[0149] Based on the timing offset 780-1, the UE 101 then sends a request control message 3002 to the BS 112-2 at 4004. For example, the request control message 3002 may be sent as part of a connection procedure for connecting to the NW 100-2 (i.e., establishing a corresponding data connection 189 in the connected mode 301). The request control message 3002 may also be sent while operating in the connected mode 301, for example, as radio resource control signaling on the PUSCH utilizing a pre-existing data connection 189. The control message 3002 may also be sent during a cell reselection / handover procedure.

[0150] Sending the request control message 3002 based on the timing offset 780-1 may mean selectively sending the request control message 3002, for example, when the timing offset 780-1 exceeds or falls below a predetermined threshold, or is non-zero, or satisfies one or more predetermined criteria (e.g., outside a predetermined tolerance). The predetermined threshold may be associated with the hardware capabilities of the UE 101. Alternatively or in addition, sending the request control message 3002 based on the timing offset 780-1 may mean that the request control message 3002 includes an information element determined based on the timing offset 780-1 or indicating the timing offset 780-1.

[0151] As usual, various options are available to implement request control message 3002.

[0152] In a first option, the request control message 3002 may indicate a timing offset 780-1. For example, the timing offset 780-1 may be expressed in a protocol time base, for example, as a count of a frame 701 or a subframe 702 of NW 100-2 and / or NW 100-1. This may be particularly applicable to situations where the protocol time bases of NWs 100-1, 100-2 are synchronized (synchronization options I and II of Table 1).

[0153] In a second option, the request control message 3002 may indicate a lower timing tolerance or an upper timing tolerance associated with the desired further timing offset 780-2. The request control message 3002 may indicate a range of values ​​for the desired further timing offset 780-2. Thus, the UE 101 may indicate whether a lower threshold exists for the desired further timing offset 780-2 for the coordinated first PO 396-1 and further POs 396-3. For example, such a lower timing tolerance may be associated with a corresponding hardware capability of the single radio wireless interface 1015 of the UE 101, for example, given by a tuning rate of an adjustable frequency filter or oscillator ( Fig.13Such a scenario is described, wherein, during the period 1831, a frequency handover is implemented). For example, the UE 101 may determine a lower timing tolerance based on a frequency distance between a carrier frequency of the first cellular NW 100-1 and a carrier frequency of the second cellular NW 100-2. Alternatively or in addition, the UE 101 may indicate whether an upper threshold exists for the desired further timing offset 780-2 for the coordinated first PO 396-1 and third PO 396-3. For example, such an upper timing tolerance may be associated with a corresponding hardware capability of the wireless interface 1015 of the UE 101, for example, given by the total power consumption of a wake-up transition from the inactive state 391 to the active state 392, possibly related to the power consumption according to the time of operation in the active state 392. In other words, if continuous operation in the active state 392 becomes advantageous in terms of power consumption compared to two wake-up transitions from the inactive state 391 to the active state 392, then a break-even point may exist. Thus, as will be appreciated from the above, the lower timing tolerance and / or the upper timing tolerance may be associated with the hardware capabilities of the modem of the radio interface of the UE.

[0154] In a third option, the request control message 3002 may indicate the hardware capability of the modem of the UE 101 to receive multiple paging signals concurrently and / or over multiple frequencies. In other words, the request control message 3002 may indicate whether the UE 101 is a single radio device or a multi-radio device, and more specifically, whether the UE 101 has two or more receive chains.

[0155] In a fourth option, UE 101 may determine a paging identity based on timing offset 780-1. The paging identity may be a temporary identity for the purpose of coordinated paging. See rules 3 and 4. The paging identity may have the same structure as identity 452, e.g., length, sequence number space, etc. However, the paging identity may be associated with another timing of another PO 396-3, rather than the second timing of the second PO 396-2 (see Fig.12 and Fig.13 ). The request control message 3002 may then indicate the paging identity. Thus, the BS 112-2 may be implicitly informed of another desired timing of another PO 396-3.

[0156] In a fifth option, the request control message 3002 may be sent, for example, by indicating the sequence number of the desired paging frame 701 and / or the sequence number of the desired subframe 702 within the paging frame 701 (see Figure 5 ) to indicate another desired timing of other POs 396-3 with a global timing reference or a protocol time base of a protocol adopted by the cellular NW 100-2.

[0157] In the sixth option, the request control message 3002 may indicate whether the UE 101 requests to increase the timing offset 780-1 or to decrease the timing offset 780-2. In other words, the UE 101 may signal whether the coordination should bring the first PO 396-1 and the other POs 396-3 closer together in the time domain if compared to the first PO 396-1 and the second PO 396-2.

[0158] Next, at 4005, a response control message 3003 is received from NW 100-2 (here, specifically from BS 112-2). Response control message 3003 is associated with request control message 3002. That is, in response to receiving request control message 3002, BS 112-2 may send response control message 3003. For example, response control message 3003 may include a pointer toward request control message 3002.

[0159] The response control message 3003 permits another timing of other POs 396 - 3 of the NW 100 - 2 .

[0160] If necessary, the data connection 189 towards the first cellular NW 100-1 and towards the second cellular NW 100-2 is optionally released at 4006 and 4007 (the UE 101 is now operating in idle mode 302 towards the first NW 100-1 and the second NW 100-2). Therefore, the UE 101 monitors the paging signals 3004, 3005 from the first cellular NW 100-1 on the first PO 396-1; and monitors the paging signals from the second cellular NW 100-2 on other POs 396-3.

[0161] As explained above, the first timing of the first PO 396-1 and the other timing of the other POs 396-3 may be coordinated with respect to the lower timing tolerance and / or upper timing tolerance of the modem of the wireless interface 1015 of the UE 101. The other timing of the other POs 396-3 may be determined to be within the timing tolerance range. Fig.14 In the illustrated scenario, the first PO 396 - 1 and the other POs 396 - 3 do not overlap but are adjacent.

[0162] At 4009 and 4010 , a paging signal, specifically a paging indicator 3004 and a paging message 3005 , is received from BS 112 - 1 .

[0163] As usual, the information content of the response control message 3003 may vary with the information content of the request control message 3002. For example, in the case where the request control message 3002 already indicates the requested another timing of some other PO 396-3, the response control message 3003 may simply confirm or deny the other timing. Differently, in the case where the request control message 3002 does not indicate a specific requested another timing of some other PO 396-3, the response control message 3003 may indicate another timing of some other PO 396-3. For example, as already explained in conjunction with the request control message 3002, the response control message 3003 may indicate another timing in the protocol time base of the cellular NW 100-2, or in the global timing reference, or using a paging indicator. Therefore, as will be appreciated, the logical distribution for determining another timing may be distributed between the UE 101 and the cellular NW 100-2. This is also illustrated in the following Table 2:

[0164]

[0165] Table 2: Example implementation of messages 3002 and 3003

[0166] exist Fig.14 In the scenario of , the BS 112-2 of the second cellular NW 100-2 may optionally notify other BSs of the second cellular NW 100-2 (e.g., within the tracking area) and / or the AMF 131 of the second cellular NW 100-2 about the paging identity at 4011. This may be done by sending a corresponding control message 3009. This helps to page the UE 101 even if the UE 101 moves from cell to cell of the second cellular NW 100-2.

[0167] Fig.15 is a flow chart of a method according to various examples. Fig.15 The method may be performed by a BS. For example, the method may be performed by BS 112-2 of the second cellular NW 100-2. Fig.15 Alternatively or additionally, Fig.15 The method may be performed by a mobility control node at the core of the NW. For example, Fig.15 The method may be performed by, for example, the AMF 131 of the second cellular NW 100-2.

[0168] In block 2011, paging is coordinated between multiple NWs. For example, a request for coordinating paging between multiple NWs is obtained from the UE. For example, a corresponding request control message (see Fig.14 : Request control message 3002).

[0169] The BS may then decide whether to grant or reject the coordination request. Depending on the result of the decision process, a positive or negative acknowledgement may be sent to the UE. For example, a response control message associated with the request control message may be sent to the UE (see Fig.14 : Response control message 3003).

[0170] For scenarios where the BS has the freedom to select a specific other timing of other POs (e.g., scenarios A, C, D, and E of Table 2), at the BS, there are various decision criteria that can be considered in selecting a specific other timing. For example, load balancing between multiple candidate POs can be considered. For example, UE mobility can be considered.

[0171] Sometimes, for example, due to UE mobility, it may be necessary to readjust another timing. For example, a situation may occur in which the UE moves from a first cell to a second cell of a second NW. The protocol time base adopted by the BS of the first cell may be offset relative to the protocol time base adopted by another BS of the second cell, that is, there may be a timing advance between the first cell and the second cell. Then, another timing may be adjusted in response to UE mobility. If the method is performed by a mobility control node of the second NW or by the first BS, the second BS may be notified accordingly.

[0172] Next, a paging signal is sent according to the coordinated timing at block 2012. For example, if the coordinated timing corresponds to another timing to implement another PO based on a paging identity of the UE different from the actual identity of the UE, the paging signal may be sent according to the another timing.

[0173] As usual, for execution at BS Fig.15 In the case of the method, the BS may not notify the core NW (e.g. the mobility control node that triggers the paging initiated via the core NW) of the new timing. In particular, the core NW UE context at the CN may not be changed. Therefore, the knowledge of the corresponding paging identity (or, in general, other POs to be used for multi-SIM identities) may be restricted to the radio access NW, for example, exchanged between neighboring BSs without involving the CN. Alternatively or in addition, the BS may also notify the core NW of another timing for other POs. The CN may then notify multiple BSs in the tracking area about the paging identity or, more generally, about other POs to be used for the UE. The CN may save the paging identity in the UE context. This applies to Fig.14 Message 3009.

[0174] Fig.16 is a flow chart of a method according to various examples. Fig.16Activities performed by a UE (eg, UE 101) and by an NW node of the NW (eg, BS 112-2 of the second cellular NW 100-2) or a core NW mobility control node (such as AMF 131 of the second cellular NW 100-2) are illustrated.

[0175] At block 2051, the multi-SIM UE 101 (which has now registered with the first cellular NW 100-1) operates towards the idle mode 302 of the first cellular NW 100-1, for example using the first identity 451. The multi-SIM UE 101 can also operate in the connected mode 301 ( Fig.16 The first identifier 451 defines the first timing of the first PO 396-1 of the first cellular NW 100-1, for example, according to rules 1 and 2 (see above). The first identifier 451 may be determined by a USIM card or an eSIM.

[0176] As usual, there may be more than one identification; for example, there may be two or three identifications, according to which the UE 101 operates, for example, in idle mode 302 towards the corresponding network (in Fig.16 , N = 1, 2, ...).

[0177] Then, at block 2052, another (e.g., second) USIM card or eSIM is detected. The other SIM card is associated with the second identification 452. Then, a NW search mode 303 is performed. This may include receiving a synchronization signal 3001 from the BS 112-2 of the second cellular NW 100-2. At block 2053, a timing difference between the first cellular NW 100-1 and the second cellular NW 100-2 may be determined.

[0178] At block 2054 , the UE accesses the second cellular NW 100 - 2 , for example, attempting to establish a corresponding data connection 189 .

[0179] At block 2054, the UE also determines a timing offset 780-1 between the first timing of the first PO 396-1 and the second timing of the second PO 396-2, the second timing of the second PO 396-2 being determined based on the second identification 452 (e.g., using Rule 1 and Rule 2 given above). As part of the connection procedure for establishing the data connection 189, the UE 101 then sends a request control message to the second cellular NW 100-2 (see Fig.14 : Request control message 3002). This is based on the determined timing offset 780-1. For example, the request control message may indicate the timing offset 780-1 and / or other parameters obtained based on the determined timing offset 780-1 (see Table 2 for several examples, where other scenarios are possible).

[0180] In block 2055, the NW node (e.g., BS 112-2 or AMF 131 of the second cellular NW 100-2) then determines another timing of other POs of the second cellular NW 100-2 or confirms the other timing (assuming that it has been indicated by the UE as part of block 2054, see Table 2). Involving the core NW in this process is possible, but not necessary.

[0181] A response control message associated with the previously received request control message is then sent to UE 101, including the result of the determination made at block 2055 (see Fig.14 , response control message 3003).

[0182] Then, at block 2056, UE 101 determines whether second cellular NW 100-2 accepts or rejects the request for coordinated paging based on the determination made at block 2055. If the request is accepted, block 2057 is executed; here, UE 101 monitors the paging signal from the second NW according to another timing of another PO, and monitors the paging signal from the first NW according to the first timing of the first PO of the first NW. If the request is rejected, at block 2058, UE 101 monitors the paging signal from the second NW according to the second timing of the second PO, and monitors the paging signal from the first NW according to the first timing of the first PO of the first NW.

[0183] At block 2059, upon receipt of the corresponding paging signal, conventional techniques for establishing a data connection 189 to the first cellular NW 100-1 and / or the second cellular NW 100-2 may be implemented.

[0184] In summary, above, a technique has been described for a multi-SIM UE to determine a timing offset between POs of multiple NWs, which are determined based on multiple identifiers of the UE. For example, when the UE registers to a cell belonging to a second cellular NW, the UE detects or calculates a timing offset between a second timing of a second PO in the second NW (e.g., determined based on the second identifier according to rules 1 and 2) and a first timing of a first PO of a cell of a first cellular NW (e.g., determined based on the first identifier according to rules 1 and 2).

[0185] The UE reports the timing offset to the RAN of the new cell of the second NW or directly to the CN of the second NW. If reported to the RAN, the RAN may report it to the CN, or in the case of RAN-based paging, the RAN may handle the reported timing offset locally. The report may be part of the connection procedure for the second NW.

[0186] The CN (in case of idle mode) or the RAN (in case of idle mode or inactive mode) signals to the UE a new further timing of further POs of the second NW based on the reported timing offset. The UE then monitors the paging signal according to the further timing.

[0187] Thereby, the power consumption of the multi-SIM UE can be significantly reduced.

[0188] In summary, various techniques are based on the following findings: In order to efficiently reduce power consumption, the UE operating mode is converted to idle or inactive, for example, as soon as there is no active transmission. During the time when the UE is in idle mode or inactive mode, the remaining source of power consumption comes from the need to convert the receiver to an active state to monitor paging signals to thereby determine whether the network has any DL data buffered for transmission to the UE. The actual power consumption of monitoring paging signals is low if compared to the power consumption required to convert the modem to an active state or even the power consumption used to keep the clock active to determine when and where to listen. According to the reference technology, the UE is required to perform such tasks independently. In order to alleviate this problem, according to various examples, paging is coordinated between multiple identifiers. In particular, the timing offset between paging from multiple NWs is reduced.

[0189] Although the invention has been shown and described with respect to certain preferred embodiments, equivalents and modifications will occur to those skilled in the art upon the reading and understanding of this specification. The present invention includes all such equivalents and modifications, and is limited only by the scope of the appended claims.

[0190] For illustration, various techniques have been described in the context of coordinating paging when a UE uses multiple identities to operate towards an idle mode of at least one cellular NW. Similar techniques may also apply when a DRX cycle is used in other modes. As a first example, the techniques described herein may be employed in a connected mode employing a DRX cycle. Here, a data connection between the at least one cellular NW and a multi-SIM UE may be maintained for at least one of the multiple identities. Thus, no random access procedure is required. Moreover, a paging signal may not be required. Instead, at the corresponding timing, the cellular NW may directly send data, for example, via the PDSCH. As a second example, there may be an inactive mode in which paging is handled by the RAN; the UE context at the CN (e.g., AMF) may not be different for the inactive mode than for the connected mode. Moreover, when operating the UE in the inactive mode, benefits may be gained from the techniques described herein. In particular, the coordination of PO may be handled by the radio access NW in the inactive mode, for example, without involving the CN.

[0191] For further illustration, various techniques have been described in the context of a connection procedure for a second NW. As part of the connection procedure, the UE may determine a timing offset between a first timing of a first PO of a first NW and a second timing of a second PO of a second NW. However, the techniques described herein are not limited to the context of a connection procedure. Other trigger criteria for performing a determination of a timing offset or a coordination request are conceivable. For example, another trigger criterion may be, for example, a cell reselection in idle mode, or a handover. In the presence of a cell reselection for a new serving cell for the second NW, this may have various effects on the PO: when the second NW for which the UE has performed cell reselection performs SFN synchronization across its cells, the timing of the second PO based on the second identifier is unchanged, and therefore, the timing offset between the first timing of the first PO of the first NW and the second timing of the second PO of the second NW remains unchanged. When the RAN or CN stores a timing offset and / or another timing of some other PO (e.g., in the UE context, see Figure 1 :UE context 459), the same timing offset or another timing can be signaled to the new cell without any UE impact. In the case where the cells of the second NW are not frame synchronized, the CN has information about the timing offsets between the cells of the second NW and can calculate a new offset for the new cell. For this purpose, another timing can be read at the CN based on the UE context. Thus, paging can be coordinated in multiple cells. Paging can also be coordinated when cell reselection is performed. This is possible even if the UE does not have to re-report another desired timing when mobility occurs.

[0192] To further illustrate, various techniques have been described where a multi-SIM UE is connected to multiple NWs. Similar techniques may be applied where a multi-SIM UE is connected to a single NW using multiple identities.

[0193] To further illustrate, various techniques have been described in which the timing of paging from multiple networks is coordinated in such a way that the timing offset between the corresponding POs is reduced by coordination. This helps to reduce power consumption at the multi-SIM UE, as detailed above. Similar techniques for timing coordination (e.g., by using a paging identifier, indicating a current timing offset and / or another desired timing offset, sending a request control message, receiving a response control message, negotiating another timing offset between the multi-SIM UE and the cellular NW, using core network UE background and / or RAN-based signaling (e.g., in the case of UE mobility, according to the configuration of messages 3001, 3002 of Table 2, etc.) to handle another timing of other POs of the cellular NW) are also applicable to such a scenario, that is, the paging timing from multiple NWs is coordinated in such a way that the timing offset between the corresponding POs is increased by coordination. This can help alleviate limitations imposed by hardware capabilities (e.g., for single radio multi-SIM UEs).

Claims

1. A method of operating a wireless communication device, the wireless communication device comprising a wireless interface having the capability of using a first identifier and a second identifier, the method comprising the following steps: - determining a timing offset between a first timing of a first paging occasion of a first network associated with the first identifier and a second timing of a second paging occasion of a second network associated with the second identifier, wherein the timing offset is determined when a cumulative timing drift between the first network and the second network exceeds a threshold; and - Based on the timing offset, sending at least one request control message to at least one of the first network and the second network to request timing coordination of paging from the first network and paging from the second network.

2. The method according to claim 1, in, The at least one request control message is sent to request another timing of further paging occasions of the second network, Another timing offset between the first timing of the first paging occasion and the another timing of the other paging occasions is smaller than the timing offset.

3. The method according to claim 1 or 2, in, The at least one request control message indicates whether the timing coordination is requested to decrease or increase the timing offset.

4. The method according to claim 1, further comprising the steps of: - receiving at least one response control message associated with the at least one request control message from the at least one network of the first network and the second network, wherein the at least one response control message permits another timing of other paging occasions of the second network, and the other timing is coordinated with the first timing, or wherein the at least one response control message permits another timing of other paging occasions of the first network, and the other timing is coordinated with the second timing.

5. The method according to claim 4, in, Another timing offset between the first timing and the another timing is smaller than the timing offset.

6. The method according to claim 5, in, The further timing offset is determined relative to at least one of a lower timing tolerance and an upper timing tolerance associated with hardware capabilities of a modem of the wireless interface.

7. The method according to claim 4, in, The first paging occasion and the other paging occasions are set in the same transmission subframe or adjacent transmission subframes of the transmission protocol of the radio link of the first network and the second network.

8. The method according to claim 4, further comprising the steps of: - converting a wireless interface of the wireless communication device from an inactive state to an active state, - During the active state: monitoring the first paging occasion for a first paging signal from the first network and monitoring the further paging occasions for a second paging signal from the second network before switching back to the inactive state.

9. The method according to claim 1, further comprising the steps of: - determining another identification based on the timing offset, The other identifier is associated with another timing of other paging occasions of the second network, The at least one request control message indicates the other identifier.

10. The method according to claim 1, in, The at least one request control message indicates the timing offset expressed in a protocol time base of the at least one of the first network and the second network.

11. The method according to claim 1, in, The at least one request control message indicates at least one of a lower timing tolerance and an upper timing tolerance for timing coordination of paging, Wherein, the at least one of the lower timing margin and the upper timing margin is associated with a hardware capability of a modem of the wireless interface.

12. The method according to claim 1, in, The at least one request control message indicates the hardware capability of the wireless interface's modem to receive multiple paging signals concurrently and / or on multiple frequencies.

13. The method according to claim 1, in, The at least one request control message is sent during a connection procedure with the second network.

14. The method according to claim 1, in, The timing offset is determined in response to cell reselection of the cell of the second network based on whether synchronization exists between cells of the second network.

15. The method according to claim 1, in, The timing offset is determined according to a predetermined schedule.

16. A method of operating a network node of a second network, the method comprising the steps of: - receiving at least one request control message from a wireless communication device to request coordination of paging from a first network and paging from the second network, the at least one request control message being associated with a timing offset between a first timing of a first paging occasion of the first network associated with a first identifier of the wireless communication device and a second timing of a second paging occasion of the second network associated with a second identifier of the wireless communication device, wherein the timing offset is determined when a cumulative timing drift between the first network and the second network exceeds a threshold; and - selectively sending at least one response control message associated with the at least one request control message to the wireless communication device, The at least one response control message permits another timing of other paging occasions of the second network, and the another timing is coordinated with the first timing.

17. The method according to claim 16, further comprising the steps of: - In response to the mobility of the wireless communication device from a first cell of the second network to a second cell of the second network: adjusting the other timing of the other paging occasions of the second network based on the timing advance of the first cell relative to the second cell.

18. A wireless communication device, comprising a wireless interface having the capability of using a first identifier and a second identifier, and comprising a control circuit, the control circuit being configured to: - determining a timing offset between a first timing of a first paging occasion of a first network associated with the first identity and a second timing of a second paging occasion of a second network associated with the second identity, wherein: The timing offset is determined when a cumulative timing drift between the first network and the second network exceeds a threshold; as well as - Based on the timing offset, sending at least one request control message to at least one of the first network and the second network to request timing coordination of paging from the first network and paging from the second network.

19. The wireless communication device according to claim 18, wherein: The control circuit is further configured to perform the method according to any one of claims 1 to 15.

20. A network node of a second network, the network node comprising a control circuit, the control circuit being configured to: - receiving at least one request control message from the wireless communication device to request coordination of paging from the first network and the second network, the at least one request control message being associated with a timing offset between a first timing of a first paging occasion of the first network associated with a first identifier of the wireless communication device and a second timing of a second paging occasion of the second network associated with a second identifier of the wireless communication device, wherein: The timing offset is determined when a cumulative timing drift between the first network and the second network exceeds a threshold; and - selectively sending at least one response control message associated with the at least one request control message to the wireless communication device, The at least one response control message permits another timing of other paging occasions of the second network, and the another timing is coordinated with the first timing.

21. The network node according to claim 20, wherein: The control circuit is configured to perform the method according to claim 16 or 17.

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