Paging collaboration

Abstract

Multiple wireless devices that collaborate are disclosed. A first wireless device monitors a paging occasion and, responsive to determining that a second wireless device is being paged, transmits an alert signal to the second wireless device.

Description

[0001] D E S C R I P T I O N

[0002] PAGING COLLABORATION

[0003] TECHNICAL FIELD

[0004] Various examples pertain to paging operation for paging wireless devices connectable to a cellular network. Various examples specifically pertain to paging groups.

[0005] BACKGROUND

[0006] There is a need to reduce power consumption of wireless devices (WD; also referred to as user equipment WD) connectable to a cellular network, while remaining accessible from the cellular network. Connectable means that the WD is configured to communicate with the cellular network and establish a data connection with the cellular network.

[0007] A first strategy to reduce power consumption of a WD used in the art is discontinuous reception (DRX) operation. When DRX operation is activated, the WD can expect transmissions from the cellular network to be restricted to ON durations of a discontinuous reception (DRX) cycle; accordingly, during OFF durations of the DRX cycle, the WD can transition at least some parts of its wireless interface into an inactive state. For example, an analog front end and / or more parts of a digital front end can be shut down. This helps to reduce the power consumption.

[0008] A second strategy to reduce power consumption is to operate the WD in a sleep mode. Sleep mode can be combined with DRX. The sleep mode provides limited connectivity if compared to a connected mode but enables an even further reduced power consumption. For example, in the context of the Third Generation Partnership Project (3GPP), example implementations of the sleep mode include the Radio Resource Control (RRC) RRCJdle mode and RRCJnactive mode. When operating in the sleep mode, the WD is not required to maintain synchronization with the cellular network. A data connection is not maintained. When the cellular network intends to transition the WD from the sleep mode to the connected mode, paging operation can be employed. In accordance with the paging operation, the cellular network transmits - at one or more paging occasions typically defined by a paging identity of the WD - one or more paging signals. If DRX is used, the DRX cycle can be aligned with the paging occasion. The WD monitors for the one or more paging signals at the paging occasion. In response to receiving the one or more paging signals that are indicative of the cellular network paging the WD, the WD attempts to transition into the connected mode by setting up a data connection. It has been observed that monitoring the paging occasion can require significant power at the WD. For example, activating an analog frontend, e.g., clock, may require significant power. For example, it may be required to perform blind decoding of a logical channel using frequency-domain processing at the WD. To mitigate this, it is possible to combine paging operating with wake-up signal operation.

[0009] A third strategy to reduce power consumption is wake-up signal (WUS) operation. A WUS is transmitted prior to the paging occasion by the cellular network only if the cellular network is paging the WD. If the WD does not receive the WUS, it does not continue to monitor the paging occasion. Thereby, fewer paging occasion are monitored by the WD, reducing power consumption. This is because attempting to receive the WUS generally tends to require less power at the WD if compared to attempting to receive paging signals. For example, this can be achieved by a less complex modulation of the WUS, if compared to the modulation of the paging signal. Alternatively or additionally, it is possible to have a smaller bandwidth allocated to the WD for the WUS transmission, to enable a smaller receive bandpass which can help to reduce a current consumption. For example, WUS operation has been standardized by the 3GPP New Radio (NR) protocol. Here, a WUS is included a downlink control message (DCI-6) masked by a PS-RNTI (Power Save RNTI) indicating a WD group to be paged by the cellular network in the subsequent DRX-On period. See, e.g., 3GPP TS 38.304 V16.7.0 (2021-12), section 7.2. Currently a study item in 3GPP is active to include an extended low power WUS, see 3GPP TR 38.869. Such WUS is designed to further reduce power consumption. Both the signal design and the receiver architecture are studied with the target to further reduce the WD power consumption. This approach evaluates more aggressive signal designs and architectures such as, e.g., signals based on on-off keying and architectures without need for LO / PLL or with LO / PLL designs to allow for ultra-low power reception. The low-power design of the receiver may lead to receivers with worse sensitivity levels compared to the main counterpart and therefore limited coverage.

[0010] WDs equipped with low-power receivers and located in the areas where the low-power WUS cannot reach the low-power receivers, due to its limited coverage, may need to fall back to legacy operation listening to paging or DCI based WUS instead. This further limits the amount of energy savings from using the low-power WUS and low-power receiver.

[0011] SUMMARY

[0012] Accordingly, a need exists for further techniques to enabling low-power operation of WDs equipped with low power receivers.

[0013] Hereinafter, techniques associated with paging operation for paging a WD are disclosed. Aspects of collaborative paging are described. Multiple WDs cooperate to facilitate the collaborative paging. Accordingly, in other words, the paging of a WD is facilitated by a paging group formed by the multiple WDs that cooperate to facilitate the collaborative paging.

[0014] The paging group includes the WD that is paged by the cellular network (also labeled “second WD”). The paging group further includes another WD (also labeled “first WD” or “paging-hub WD”) that monitors a paging occasion to determine whether the second WD is being paged and if the second WD is being paged transmits an alert signal. The alert signal can be received by the second WD and the second WD can then take one or more actions such as activating its main receiver, monitoring another paging occasion, or directly connecting to the cellular network.

[0015] The paging-hub functionality may be fixedly assigned to a given one of the WDs included in the paging group. For example, a master WD that manages the paging group may execute the paging-hub functionality. Alternatively, it would also be possible that different WDs included in the paging group take turns in executing the paging-hub functionality. Thus, at a first point in time a first WD included in the paging group may be the paging-hub WD; while at a subsequent second point in time a second WD included in the paging group can be the paginghub WD.

[0016] A method for use in a first WDs disclosed. The first WD is connectable to a cellular network. The first WD and a second WD are included in a paging group. The second WD may also be connectable to the cellular network. The method includes monitoring a paging occasion. The paging occasion is monitored to determine whether the cellular network pages the second WD. The method further includes, upon determining that the cellular network pages the second WD, generating and transmitting an alert signal for the second WD.

[0017] A first WD comprising compute circuitry that is configured to perform such method is also disclosed.

[0018] A system is disclosed that includes the first WD and the second WD.

[0019] A system is disclosed that includes multiple WDs included in a paging group.

[0020] A method for use in a second WDs disclosed. The second WDs connectable to a cellular network. A paging group includes the second WD and a first WD. The method includes receiving, from the first WD, an alert signal indicative of the cellular network paging the second WD.

[0021] A method for use in a node of a cellular network is disclosed. The method includes maintaining a first registry entry for a WD connectable to the cellular network. The method further includes maintaining a second registry entry for a paging group that includes the WD. The method still further includes triggering paging of the WD based on the first registry entry as well as based on the second registry entry.

[0022] The method may further include maintaining a third registry entry for a further WD connectable to the cellular network. The method may further include triggering paging of the further WD based on the second registry entry as well as based on the third registry entry.

[0023] A node is disclosed, the node including compute circuitry that is configured to perform such method as described above.

[0024] A system is disclosed that includes such node and one or more WDs included in a paging group.

[0025] A method for use in a first WD is disclosed. The first WD is connected or can be connected (i.e. , is connectable) to a cellular network. The method includes monitoring paging occasions. The paging occasions are associated with a paging identity of the first WD. The method further includes, upon collaborative paging being activated for the first WD and before one or more second WDs: alternating between (i) attempting to receive an alert signal that is transmitted by the one or more second WDs, and (ii) monitoring at least one of the paging occasions or further paging occasions. The at least one of the paging occasions or the further paging occasions are monitored for determining whether the cellular network pages the first WD or the one or more second WDs.

[0026] A first WD comprising compute circuitry and configured to perform such method is also disclosed.

[0027] A system is disclosed that includes the first WD and the one or more second WDs.

[0028] A method for use in a node of a cellular network or in a WD connectable to the cellular network is disclosed. The method includes determining timing information. The timing information defines timeslots according to which the multiple WDs engage in collaborative paging alternate between monitoring paging occasions for determining whether any one of the WDs is being paged, and attempting to receive an alert signal that is transmitted by another one of the WDs. An apparatus including compute circuitry and configured to perform such method is also disclosed. The apparatus can be a node of a cellular network or a WD that is connectable to the cellular network.

[0029] A system including such apparatus and such first WD is also disclosed.

[0030] It is to be understood that the features mentioned above and those yet to be explained below may be used not only in the respective combinations indicated, but also in other combinations or in isolation without departing from the scope of the invention.

[0031] BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 schematically illustrates a wireless communication system including a WD connectable to a cellular network and the cellular network, wherein the cellular network is configured for direct paging of the WD.

[0033] FIG. 2 is a flowchart of a method according to various examples.

[0034] FIG. 3 schematically illustrates the wireless communication system including the WD connectable to the cellular network and the cellular network, wherein the cellular network is configured for paging of the WD through a paging-hub WD according to various examples.

[0035] FIG. 4 is a flowchart of a method according to various examples, the method being for use in a paging-hub WD.

[0036] FIG. 5 is a flowchart of a method according to various examples, the method being for use in a paging-hub WD.

[0037] FIG. 6 is a flowchart of a method according to various examples, the method being for use in a WD being paged by the cellular network.

[0038] FIG. 7 is a flowchart of a method according to various examples, the method being for use in a node of a core network of the cellular network.

[0039] FIG. 8 is a signaling diagram according to various examples.

[0040] FIG. 9 is a signaling diagram according to various examples.

[0041] FIG. 10 schematically illustrates a WD according to various examples.

[0042] FIG. 11 schematically illustrates a control node of a core network of the cellular network according to various examples.

[0043] FIG. 12 schematically illustrates a base station according to various examples.

[0044] FIG. 13 schematically illustrates multiple operational modes in which a WD can operate according to various examples.

[0045] FIG. 14 schematically illustrates multiple WDs alternatingly taking turn to monitor paging occasions on behalf of each other accordingly to various examples.

[0046] FIG. 15 is a flowchart of a method according to various examples.

[0047] FIG. 16 schematically illustrates a time-dependent behavior of multiple WDs engaging in collaborative paging according to various examples.

[0048] FIG. 17 is a flowchart of a method according to various examples.

[0049] DETAILED DESCIRPTION

[0050] Some examples of the present disclosure generally provide for a plurality of circuits or other electrical devices. All references to the circuits and other electrical devices and the functionality provided by each are not intended to be limited to encompassing only what is illustrated and described herein. While particular labels may be assigned to the various circuits or other electrical devices disclosed, such labels are not intended to limit the scope of operation for the circuits and the other electrical devices. Such circuits and other electrical devices may be combined with each other and / or separated in any manner based on the particular type of electrical implementation that is desired. It is recognized that any circuit or other electrical device disclosed herein may include any number of microcontrollers, a graphics processor unit (GPU), integrated circuits, memory devices (e.g., FLASH, random access memory (RAM), read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), or other suitable variants thereof), and software which co-act with one another to perform operation(s) disclosed herein. In addition, any one or more of the electrical devices may be configured to execute a program code that is embodied in a non-transitory computer readable medium programmed to perform any number of the functions as disclosed.

[0051] In the following, embodiments of the invention will be described in detail with reference to the accompanying drawings. It is to be understood that the following description of embodiments is not to be taken in a limiting sense. The scope of the invention is not intended to be limited by the embodiments described hereinafter or by the drawings, which are taken to be illustrative only.

[0052] The drawings are to be regarded as being schematic representations and elements illustrated in the drawings are not necessarily shown to scale. Rather, the various elements are represented such that their function and general purpose become apparent to a person skilled in the art. Any connection or coupling between functional blocks, devices, components, or other physical or functional units shown in the drawings or described herein may also be implemented by an indirect connection or coupling. A coupling between components may also be established over a wireless connection. Functional blocks may be implemented in hardware, firmware, software, or a combination thereof.

[0053] Various aspects relate to a communication system. For example, the communication system may be implemented by a WD and an access node of a cellular network. For example, the access node may be implemented by a base station (BS) of a cellular network. Downlink (DL) signals may be transmitted by the BS on the wireless link and received by the WD. Uplink (UL) signals may be transmitted by the WD and received by the BS.

[0054] Hereinafter, techniques will be described that facilitate operation of a WD in a sleep mode. The sleep mode may restrict connectivity, e.g., in terms of when the WD can receive data and / or in terms of what signals the WD can receive. The sleep mode (that may also be referred to as disconnected mode or limited connectivity mode) can generally enable a WD to shut down partly or fully one or more components of its wireless interface. When a WD operates in the sleep mode, a WD-specific data connection between the cellular NW and the WD is released. By using the sleep mode, the power consumption at the WD can be reduced.

[0055] Techniques will be described that facilitate DRX operation. As a general rule, a WD using DRX operation, i.e. , alternatingly switch at least parts of its wireless interface between an active state and an inactive state. When in the inactive state, the wireless interface may be unfit to receive data. By using the DRX operation, the power consumption at the WD can be reduced. According to examples, the DRX operation is combined with the sleep mode. To facilitate this, paging operation is employed. The cellular NW can attempt to contact / page the WD, e.g., by transmitting one or more paging signals at the paging occasion. When a WD detects that it is being paged, it can transition from the disconnected mode to a connected mode. The transition from the disconnected mode to the connected mode can involve a random-access (RACH) procedure.

[0056] Next, details with respect to such paging operation in a reference implementation is discussed in connection with FIG. 1 and FIG. 2.

[0057] FIG. 1 schematically illustrates aspects with respect to a communication system 100 according to a reference implementation. A WD 121 is configured to communicate with a cellular network 130. The WD 121 can connect to the cellular network 130. The cellular network 130 includes a radio-access network 138. The radio access network 138 includes multiple base stations, one of which - the base station 139 - is illustrated in FIG. 1. The radio access network 138 is connected to a core network 131 including multiple nodes such as a mobility control node 132. The mobility control node 132 can provide a paging trigger message to the radio-access network 138, triggering the radio-access network 138 to transmit paging signals at paging occasions of the WD 121. The WD 121 monitors the paging occasions. Aspects with respect to the WD 121 monitoring the paging occasion are described in connection with FIG. 2.

[0058] FIG. 2 is a flowchart of a method according to a reference implementation. FIG. 2 illustrates activities on a WD associated with paging operation in a reference implementation. For example, FIG. 2 illustrates activities of the WD 121 when operating in a sleep mode. FIG. 2 illustrates paging operation in conjunction with DRX operation and WUS operation. At box 5005, the WD deactivates its receiving circuitry. For example, both a main receiver and a low power receiver may be transitioned to an inactive state. This occurs in-between two subsequent paging occasions. By transitioning its receiver circuitry to the inactive state, power consumption can be reduced.

[0059] Box 5010 is used to determine if a paging occasion associated with its paging identity (e.g., 3GPP Temporary Mobile Subscriber Identity, TMSI, or 3GPP Radio Network Temporary Identifier, RNTI) is imminent. If so, the low power receiver is transitioned to the active state at box 5015.

[0060] At box 5016 the signal level, e.g., the signal-to-noise ratio on a frequency band assigned to wake-up signals is checked. Other examples for measuring the signal level are low-power reference or low-power WUS received signal power and low-power reference or low-power WUS received signal quality. If the signal is sufficiently strong, the WD attempts to receive a wake-up signal at box 5020 using the low power receiver. This may include time domain processing to match received signals to a wake-up signal reference signal shape. If the wakeup signal is not received at the box 5025, the method proceeds at the box 5005, i.e., the low power receiver is transitioned to the inactive state.

[0061] Else, if the wake-up signal is received, the WD can conclude that it is possibly being paged. The wake-up signal typically does not unambiguously resolve whether any particular WD is being paged. This is because the wake-up signal cannot carry unique paging identities due to its simple construction. Accordingly, in order to determine whether it is being paged, the WD transitions its main receiver into the active state at box 5030. A synchronization signal is then received at box 5035 to establish synchronization with the cellular network.

[0062] Box 5030 and box 3035 are also executed if, at box 5016, it is determined that the signal is not sufficiently strong. This may be the case in cell-edge scenarios where due to the low signal level wake-up signal operation is not feasible.

[0063] Then, at box 5040 in box 5045, the WD attempts to receive paging signals. More specifically, at box 5040, the WD attempts to receive a paging indicator, for example, by blind decoding a control channel. For example, the WD may attempt to receive paging downlink control information (DCI) on a physical control channel such as the 3GPP physical downlink control channel (PDCCH). Box 5040 may include blind decoding. If the paging indicator is not received, the method commences at box 5005.

[0064] Else, if the paging indicator is received, the paging indicator includes time-frequency resources of a subsequent paging message that the WD attempts to receive at box 5045. For example, a layer 3 paging message may be received. The paging message may be received on a physical downlink shared channel such as the 3GPP Physical Downlink Shared Channel (PDSCH).

[0065] The paging message includes one or more paging identities of one or more WDs. Based on the paging message, the WD can determine whether it is being paged, box 5050. If the WD determines that it is not being paged, it transitions its receiver circuitry to an inactive state at box 5005; otherwise, a connection is established at box 5055, e.g., by executing a RACH procedure.

[0066] Various techniques are based on the finding that the reference paging operation at the WD according to FIG. 2 is relatively energy costly. For instance, the WD may be required to transition the main receiver into the active state each time a WUS is received; even if ultimately the WD is not being paged. Also, for cell edge scenarios - as discussed in connection with box 5016 - WUS operation is not feasible. Thus energy-costly boxes 5040, 5045 are executed.

[0067] The energy consumption can be quantified as follows: Let the DRX cycle be of duration DRX - The DRX cycle correlates with the periodicity of the paging occasions (box 5010). Within each DRX cycle, the WD monitors the paging occasion to attempt to receive one or more paging signals. EDRXdenotes the energy consumption associated with this during the ?DRX seconds. Thus, during N DRX cycles, the net energy consumption per WD is:

[0068] E0= NEORX(1).

[0069] To reduce the reference energy consumption according to Equation (1), the paging operation as shown in FIG. 2 is modified.

[0070] According to various examples, conventional paging operation is modified by using groups of WDs that collaborate in connection with the paging operation. A paging group, or group of WD, is a set of WDs that engage in collaborative paging as disclosed herein. The groups may hence be referred to as paging collaboration groups or simply paging groups. By means of the paging groups, WDs are aggregated so that a first WD of the group reads paging for a second WD of the group. The first WD, upon detecting that the cellular network pages the second WD, transmits an alert signal to the second WD in the group. The alert signal informs the second WD that the cellular network pages the second WD. Accordingly, the alert signal may also be termed “paging alert signal”. The second WD can then take appropriate action, e.g., monitor its paging occasion or directly perform a RACH procedure. Such techniques enable to further reduce the power consumption at the second WD. The second WD may monitor paging occasion more sparsely. Attempting to receive the alert signal may be associated with lower power consumption. The alert signal is a low-complexity signal with simple modulation and coding scheme such as on-off keying, binary frequency shift keying, Manchester coding.

[0071] FIG. 3 illustrates aspects with respect to the communication system 100. The communication system 100 is configured in accordance with various disclosed examples. The communication system 100 includes a paging group 120. In particular, the WD 121 is part of a paging group 120. The paging group 120 also includes the WDs 122, 123, 129.

[0072] The WD 129 acts as a hub for paging of the remaining WDs 121, 122, 123 of the paging group 120. It is, accordingly, referred to as paging-hub WD 129 hereinafter.

[0073] Different considerations are conceivable for determining which particular WD acts as the paging hub. For example: The paging-hub WD 129 may be determined as the WD having best coverage amongst all WDs 121, 122, 123, 129. The paging-hub WD 129 may be determined as the WD having largest battery capacity and / or highest battery state-of-charge amongst all WDs 121 , 122, 123, 129. The paging-hub WD 129 may be determined in accordance with timing information (as will be later explained in connection with FIG. 15); this timing information distributes monitoring activity (i.e. , the energy-expensive task of monitoring paging occasions on behalf of other WDs in the paging group) amongst the WDs in the paging group. The paginghub WD 129 may be elected by the WDs of the paging group 120. The paging-hub WD 129 may be fixedly predefined.

[0074] Next, to exemplify the paging operation employing the paging group 120, the scenario in which the cellular network 130 pages the WD 121 is discussed. The mobility control node 132 provides a paging trigger to the RAN 138. The BS 139 then transmits one or more paging signals, e.g., a paging indicator and a paging message (cf. FIG. 2: box 5040 and box 5045). The one or more paging signals are indicative of the cellular network 130 paging the WD 121. The one or more paging signals are received by the paging-hub WD 129. The paging-hub WD 129 monitors the paging occasion. The WD 121 does not monitor the paging occasion. The paginghub WD 129 decodes the one or more paging signals and determines that the cellular network 130 pages the WD 121. Since the WD 121 is part of its paging group 120, the paging-hub WD 129 transmits an alert signal to the WD 121. The alert signal may be indicative of the cellular network paging the WD 121. The alert signal wakes-up the WD 121. Upon receiving the WD 121 , the WD 121 may attempt to connect to the cellular network 100 (cf. FIG. 2: box 5055), e.g., by performing a RACH procedure.

[0075] As will be appreciated from the above, the WD 121 is not required to monitor the paging occasion (at least until receiving the alert signal). This means that the wireless device 121 is not expected, by the cellular network, to attempt receiving paging signals in the paging occasion. The WD 121 can rather attempt to receive the alert signal, e.g., in accordance with a certain DRX cycle. Attempting to receive the alert signal may be less power consuming than attempting to receive paging signals, e.g., as in the scenario of FIG. 2. FIG. 4 is a flowchart of a method according to various examples. FIG. 4 illustrates actions and method steps for use in a WD associated with paging operation. In FIG. 4, the WD executing the method acts as a paging-hub WD for one or more other WDs included in, i.e. belonging to, the same paging group as the paging-hub WD. The WD executing the method of FIG. 4 may be labeled “paging watchdog”, because the remaining WDs offload their burden to monitor paging occasions onto the paging watchdog WD. For example, FIG. 4 illustrates activities of the WD 129 of the communication system 100 of FIG. 3.

[0076] The paging-hub WD, while executing the method of FIG. 4, may generally operate in a sleep mode or in a connected mode. If the paging-hub WD operates in the sleep mode, it may not only determine whether the cellular network pages one or more other WDs part of the same paging group; but also determine whether itself is being paged by the cellular network. On the other hand, the paging-hub WD operates in the connected mode, a data connection is established in between the paging-hub WD and the cellular network and the paging-hub WD does not expect to be paged by the cellular network. Nonetheless, the paging-hub WD can monitor paging occasions for one or more further WDs of the paging group.

[0077] At optional box 5105, the paging-hub WD deactivates its receiving circuitry. For example, both a main receiver and a low-power receiver may be transitioned to an inactive state. This occurs in-between two subsequent paging occasions. By transitioning its receiver circuitry to the inactive state, power consumption can be reduced.

[0078] Box 5105 corresponds to DRX operation. DRX operation is generally optional. Accordingly, box 5105 is generally optional. In some examples, the paging-hub WD may not deactivate its receiver circuitry. In some examples, the paging-hub WD may not employ DRX. For instance, a low-power receiver or even a main receiver may be continuously operated in the active state. For example, the paging-hub WD may monitor multiple DRX patterns or groups at the same time.

[0079] Box 5110 is used to determine if a paging occasion to be monitored is imminent. The paging occasion may be one of the paging occasions summarized in TAB. 1 below.

[0080] TAB. 1 : Examples of paging occasions to be monitored by paging-hub WD. Also combinations are possible. There may be a pre-configured mapping to determine a timing of the paging occasion based on the paging identity.

[0081] For example, - as shown in TAB. 1 example 1 - the paging-hub WD may be configured to monitor its own paging occasions. These paging occasions are associated with a networklevel paging identity uniquely assigned to the paging-hub WD. A network-level paging identity is valid throughout the cellular network or at least in extended region of the cellular network. The network-level paging identity has a validity not limited to the paging group only. An example includes the 3GPP IMSI (International Mobile Subscriber Identity) valid across multiple or even all cellular networks. It is used to identify the individual subscriber, and it's stored in the SIM card. Another example is the TMSI (Temporary Mobile Subscriber Identity): This is a temporary identity assigned by the cellular network to the WD. It is used instead of the I MSI to ensure the privacy of the subscriber. Yet another example is the LMSI (Local Mobile Subscriber Identity). These would be the same paging occasions that the paging-hub WD monitors in accordance with reference implementations of the paging operation, e.g., as previously discussed in connection with FIG. 2. In such a scenario, the cellular network can transmit a paging signal that is indicative of the cellular network paging another WD of the paging group at the paging occasion associated with the paging identity of the paging-hub WD. The cellular network may alternatively or additionally transmit a paging signal that is indicative of the cellular network paging the paging-hub WD (given that the paging-hub WD also operates in the sleep mode).

[0082] Alternatively or additionally, - as shown in TAB. 1 example 2 - the paging-hub WD may be configured to monitor a paging occasion associated with a group identity of the paging group. The group identity may not be assigned to any WDs but may be reserved for paging groups. The group identity may uniquely identify the group across the cellular network; i.e. , different paging groups have different group identities. In such a scenario, the cellular network can transmit a paging signal that is indicative of the cellular network paging another WD of the paging group at the paging occasion associated with the paging identity of the paging group.

[0083] Alternatively or additionally, - as shown in TAB. 1 example 3 - the paging hub WD may be configured to monitor one or more paging occasions associated with network-level paging identities of one or more further WDs in the paging group. For instance, referring to the communication system 100 illustrated in FIG. 3, the paging-hub WD 129 may be configured to monitor the paging occasions associated with the paging identities of each of the WDs 121, 122, 123 part of the paging group 120. In such a scenario, the cellular network can transmit a paging signal that is indicative of the cellular network paging another WD of the paging group at the paging occasion associated with the paging identity of the another WD.

[0084] If a paging occasion is imminent, a low-power receiver may be transitioned to the active state at box 5115, and the WD attempts to receive a wake-up signal at box 5120 using the low power receiver. This may include time-domain processing to match received signals to a wakeup signal reference signal shape.

[0085] The WUS may be indicative of a network-level paging identity of the paging-hub WD. The wake-up signal may uniquely identify the paging-hub WD. In other scenarios, the paging signal may not uniquely identify the paging-hub WD. The WUS may be shared amongst a larger count of WDs.

[0086] If the wake-up signal is not received at the box 5125 (or if a WUS is received that is not directed to the paging-hub WD), the method proceeds at the box 5105, i.e., the low power receiver is transitioned to the inactive state. Else, upon receiving the WUS, the method commences at box 5130.

[0087] As a general rule, WUS operation is optional. The paging-hub WD may or may not employ WUS at a paging occasion. For instance, without WUS operation, box 5115, box 5120, and box 5125 can be skipped. The method may commence directly at box 5130. At optional box 5130, the paging-hub WD transitions its main receiver into the active state. A synchronization signal is then received at optional box 5135 to establish synchronization with the cellular network. Box 5130 and box 5135 are only executed if DRX operation is used.

[0088] The paging-hub WD then commences to monitor the paging occasion. Monitoring the paging occasion includes attempting to receive a paging indicator at box 5140. At box 5140, the paging-hub WD attempts to receive a paging indicator, for example, by blind decoding a control channel. For example, the paging-hub WD may attempt to receive paging DCI on a physical control channel such as the 3GPP PDCCH. Box 5140 may include blind decoding. If the paging indicator is not received, the method commences at box 5105.

[0089] Else, if the paging indicator is received, the paging indicator includes time-frequency resources of a subsequent paging message that the paging-hub WD attempts to receive at box 5145. Monitoring the paging occasion also includes box 5145. For example, a Layer 3 paging message may be received. The paging message may be received on a physical downlink shared channel such as the 3GPP Physical Downlink Shared Channel (PDSCH).

[0090] The paging message includes one or more paging identities of one or more WDs. Based on the paging message, the paging-hub WD can determine - at box 5150 - whether one or more WDs of the paging group are being paged. In the affirmative, the paging-hub WD generates and transmits an alert signal at box 5155. WDs monitors the channels continuously (i.e. , continuous reception operation) or based on a predefined duty-cycled patterns for potential alert signal.

[0091] TAB. 2 lists some options for the paging identity included in a paging signal that is indicative of the cellular network paging a given WD.

[0092] TAB. 2: Some options for paging identities included in a paging signal, e.g., a paging message.

[0093] For instance, the cellular network may transmit the paging message carrying the paging identity of the paging-hub WD according to TAB. 2: example 1. Here, the paging message may further carry a flag that is indicative of the cellular network intending to page one or more of the remaining WDs in the paging group. The paging-hub WD may accordingly understand that even though it receives the paging message that is indicative of its own paging identity, the cellular network in fact attempts to page one or more further WDs. This may be combined with the scenarios of example 1 or 2 of TAB. 1. In such a case, the paging-hub WD may not need to be aware of the particular one or more further WD is being paged by the cellular network. The paging-hub WD can transmit an alert signal that does not uniquely identify the page WD. Alternatively, in the variant of TAB. 2: example 1, it would also be possible that a paging message carrying the paging identity of the paging-hub WD is received in the paging occasion associated with the paging identity of the given WD that is being paged (cf. TAB. 1: example 3). Thereby, the paging-hub WD may be aware of the cellular network attempting to page at particular WD.

[0094] In the scenario of TAB. 2: example 2, the paging message may carry the paging group identity. Such a scenario is combinable with any one of the variants associated with TAB. 1.

[0095] Finally, it is also possible that the paging message carries the paging identity of the given WD being paged, cf. TAB. 2, example 3. Again, such scenarios combinable with any one of the examples discussed in TAB. 1.

[0096] Generating the alert signal means that the alert signal is generally different than any paging signal received while monitoring the paging occasion. The alert signal is newly constructed at the paging-hub WD. Generating the alert signal is different than relaying a paging signal at a relay. The alert signal can be generated based on configuration information previously obtained from the cellular network and / or the WD to be alerted. For instance, the alert signal can be generated based on a paging identity of the WD to be alerted. For instance, a bit sequence to be encoded by the alert signal may be determined based on the paging identity. This task can be executed at the paging-hub WD. WD may listen / monitor for potential alert signals based on a predefined duty-cyled scheme using its low-power receiver.

[0097] If the paging-hub WD operates in the sleep mode, it may optionally execute box 5160; here, the paging-hub WD can determine whether it is being paged itself; in the affirmative, can execute a connection establishment, e.g., RACH procedure, at box 5165.

[0098] Next, details in connection with the alert signal are discussed. Various options for the alert signal are shown in TAB. 3.

[0099] TAB. 3: Options for the alert signal. Sometimes the paging-hub WD may not be aware which particular WD of the paging group is being paged by the cellular network. In particular in such a scenario, example 2 of TAB. 3 may be preferred.

[0100] As shown in TAB. 3: example 1 , it is possible that the alert signal uniquely identifies each WD that is being paged by the cellular network.

[0101] To uniquely identify a given WD of the paging group that is being paged, the alert signal may carry a network-level paging identification of that WD that is being paged. If more than a single WD is being paged, multiple alert signals may be generated and transmitted (e.g., subsequently), each carrying a respective single one of the associated network-level paging identifications. It would be possible that the alert signal carries a 3GPP TMSI of the WD being paged. A single alert signal may also carry multiple network-level paging identities. As a general rule, a network-level paging identification that uniquely identifies each WD may be comparatively long. However, it is possible that the alert signal is transmitted using a comparatively low transmit power, thereby limiting interference of a long alert signal with other signals. Nonetheless, there can be scenarios according to which it is desirable to limit the information content carried by the alert signal. In such scenarios, it may be preferable that the alert signal uniquely identifies each WD that is being paged by the cellular network by carrying a group-level paging identification. In other words, the alert signal may not uniquely identify the WD that is being paged on network level (i.e. , avoiding ambiguities across the entire cellular network), but rather uniquely identify the WD that is being paged on group level (only avoiding ambiguities within the paging group). Here, different paging groups within the cellular network may reuse the same group-level paging identifier for different WDs.

[0102] Group-level paging identities may be assigned at the time of a WD joining a paging group. Group-level paging identities may be assigned by a master WD of the paging group. Group-level paging identities may be assigned by the cellular network, e.g., a mobility control node at the core network. For instance, group-level paging identities may be maintained in a registry entry at a mobility control node at the core network.

[0103] The alert signal may be associated with the paging group. The alert signal may be specific for the paging group.

[0104] Different paging groups may use different alert signals. Different paging groups may use alert signals allocated to orthogonal time-frequency resources. I.e., alert signals may be transmitted in time-frequency resources reserved for a particular paging group. Different paging groups can be associated with different paging group identities and the alert signals can carry the paging group identity.

[0105] To give a concrete example, the alert signal may carry a paging-group identity - thereby uniquely associating the alert signal with a given paging group; and may further carry a group- level paging identity of the WD being paged by the cellular network.

[0106] As shown in TAB. 3: example 2, it is possible that the alert signal does not uniquely identify each WD that is being paged by the cellular network. In particular, it is possible that the alert signal does not even uniquely identify the paged WD within the paging group. For instance, it would be possible that the alert signal does not discriminate at all between different WDs. In such a scenario, all WDs that receive the alert signal within the group (the alert signal can be group-specific, as explained above), can wakeup and subsequently monitor its paging occasion to determine whether they are being paged by the cellular network. Even such a scenario can have benefits in terms of energy consumption, because relatively size-limited paging groups can be formed to avoid frequent wake up.

[0107] On the other hand, an alert signal that uniquely identifies a particular WD that is being paged (cf. TAB. 3: example 2) by the cellular network enables that WD upon receiving the alert signal to commence directly with the attempt to establish a connection with the cellular network, e.g., commence directly with a RACH procedure. The WD that is being paged is informed accordingly by means of the alert signal; the WD that is being paged is not required to monitor its paging occasion. This reduces the power consumption at the WD.

[0108] Next, various options for implementing the alert signal are disclosed. As a general rule, the alert signal can be a signal that can be relatively simple with low-complexity to receive, i.e., can be received without requiring significant power consumption at the receiving node. The alert signal can have a relatively simple modulation and coding scheme. The alert signal may have a simple modulation if compared to a paging signal such as a paging indicator or a paging message. The alert signal may be generally transmitted using a comparatively small transmit power, in particular of the paging group includes WDs that are co-located.

[0109] The alert signal may be receivable by time-domain processing, e.g., at a low-power receiver. Time-domain processing can include one or more of the following: Filtering using timedomain filters, e.g., finite impulse response or infinite impulse response filters; direct demodulation of amplitude, phase, or frequency modulated signals in the time domain.

[0110] The alert signal may be an On-Off-keying (OOK) modulated signal conveying information using the presence or absence of a carrier signal. In OOK, a "1" is represented by the presence of the carrier, and a "0" is represented by its absence.

[0111] For example, the alert signal may be a WUS. A WUS can have lower complexity than paging signals.

[0112] The alert signal may be a dedicated WUS only transmitted by the paging-hub WD. Alternatively, the alert signal may mimic a network-originating wake-up signal used by the cellular network for waking-up other WDs. For instance, the alert signal may be transmitted at a time-frequency offset prior to a certain paging occasion associated with the network-level paging identity of the WD. Thereby, wake-up signal transmission can be delegated by the cellular network to the paging-hub WD. The BS may not be required to transmit the WUS; the WUS is rather transmitted by the paging-hub WD.

[0113] For instance, the alert signal may be transmitted on time-frequency resources allocated by the cellular network to the paging-hub WD for transmitting the alert signal. Network allocated resources may be used. This can limit interference.

[0114] The alert signal may be transmitted in an unlicensed band. An unlicensed band refers to a portion of the radio frequency spectrum where individual users are allowed to operate radio frequency devices without obtaining a specific license from the national regulatory authority and / or without a central scheduling authority. For instance, a listen-before-talk process may be employed for transmitting the alert signal on the unlicensed band.

[0115] For example, the alert signal may be transmitted on a device-to-device radio channel. A device-to- device radio channel may also be labeled as sidelink radio channel. Pre-configured sidelink resources may be employed that are allocated to the paging-hub WD by the cellular network for communicating on the sidelink radio channel.

[0116] It would be possible that the alert signal is transmitted using another radio access technology. For instance, the paging signal may be received using a first radio access technology, e.g., 3GPP 5G or 6G. The alert signal may, on the other hand, be transmitted using a second radio access technology, e.g., Bluetooth or Wi-Fi.

[0117] As will be appreciated from the above, to be able to appropriately monitor the paging occasion of paging occasions to determine whether the cellular network pages a WD of the paging group and to be able to generate and transmit the alert signal, the paging-hub WD may require certain configuration information. As a general rule, such configuration information may be provided to the paging-hub WD upon joining the paging group. The configuration information could be provided by the cellular network or another WD of the paging group. It would also be possible that the paging group is established by the paging-hub WD - e.g., acting as a master node for the paging group in which case the configuration information may be determined by the paging-hub WD itself. As a general rule, the paging group may be established responsive to a user request obtained from a user of one or more of the WDs. Details with respect to such set up and configuration of the paging group are next discussed in connection with FIG. 5.

[0118] FIG. 5 is a flowchart of a method according to various examples. FIG. 5 illustrates a registration and configuration phase prior to a WD acting as paging-hub WD for one or more other WDs included in the same paging group as the paging-hub WD. For example, FIG. 5 illustrates activities of the WD 129 of the communication system 100 of FIG. 3. The method of FIG. 5 may precede the method of FIG. 4.

[0119] At box 5205, the WD provides, to the cellular network, an indication that it is capable of being part in a paging group. The capability may include one or more of the following, (i) Capability of the WD to act as a paging-hub WD. (ii) Capability of the WD to monitor paging occasions on behalf of one or more other UEs. (iii) Capability of the WD to generate and to transmit the alert signal, (iv) Capability of the WD to receive the alert signal.

[0120] At box 5210, the paging group is being set up. For instance, the WD may form a new paging group or join a pre-existing paging group. Box 5210 may be executed upon indicating the capability to be part of the paging group at box 5205.

[0121] Setting up the paging group may be implemented as a subscription. I.e., it would be possible that the cellular network or one or more WDs advertise a paging group and that the WD then subscribes thereto.

[0122] Setting of the paging group may be initiated by the WD or another WD of the paging group. The paging group may be a WD-initiated aggregation of collaborating WDs. For instance, the WDs forming part of the subsequently established paging groups may determine that they are co-located, i.e., located in the proximity and having similar mobility patterns. Examples would be a paging group formed by a smart phone and multiple wearable devices associated with the same user. Further examples would be paging groups formed by WDs co-located in the same vehicle.

[0123] As a general rule, box 5210 can accordingly include providing a request for establishing or participating in the paging group to the cellular network and / or one or more other WDs (e.g., a master WD of the paging group) to be part of the paging group. Box 5210 may include obtaining a request for establishing or participating in the paging group from the cellular network or another WD of the paging group.

[0124] At box 5215, configuration information for the paging group and the operation as the paging-hub WDs obtained.

[0125] Box 5215 can include obtaining a group identity of the paging group. The group identity may be used for generating group-specific alert signals (cf. FIG. 4: box 5155). The group identity may be used for determining whether the cellular network pages a WD included in the paging group (cf. FIG. 4: box 5145); the group identity may be included in a paging message received from the cellular network.

[0126] Box 5215 can include obtaining an indication of network-level paging identities of one or more further WDs included in the paging group. Such information can be obtained, e.g., from the cellular network and / or from the other WDs. Such network-level paging identities of one or more further WDs included in the paging group may be used for generating device-specific alert signals (cf. FIG. 4: box 5155). Such network-level paging identities of one or more further WDs included in the paging group may also be used for determining whether the cellular network pages such a further WD; the network-level paging identity may be included in a paging message received from the cellular network (cf. FIG. 4: box 5145).

[0127] Box 5215 can include obtaining an indication of group-level paging identities of one or more further WDs included in the paging group. Such information can be obtained, e.g., from the cellular network and / or from the other WDs. Such group-level paging identities of one or more further WDs included in the paging group may be used for generating device-specific alert signals (cf. FIG. 4: box 5155). Such group-level paging identities of one or more further WDs included in the paging group may also be used for determining whether the cellular network pages such a further WD; the group-level paging identity may be included in a paging message received from the cellular network (cf. FIG. 4: box 5145).

[0128] Configuration information obtained at box 5215 may enable the WD to act as the paginghub WD. Configuration information obtained at box 5215 may enable the WD to monitor one or more paging occasions for determining whether the cellular network pages one or more other WDs included in the paging group. Configuration information at box 5215 may enable the WD to generate and transmit the alert signal upon determining that the cellular network pages one or more other WDs included in the paging group.

[0129] At box 5215, a configuration used for generating and / or transmitting the alert signal may be obtained.

[0130] Such configuration may be indicative of at least one of a timing of transmitting the alert signal, time-frequency resources for transmitting the alert signal, a time offset with respect to a paging occasion associated with a network-level paging identification of the second WD, a frequency offset with respect to a paging occasion associated with a network-level paging identification of the second WD, a network-level paging identification of the second WD, a sequence design of the alert signal, or a modulation scheme of the alert signal.

[0131] At box 5220, it is then determined whether paging-hub operation is to commence. If paging-hub operation is to commence, it would be possible to execute the method of FIG. 4. This can be based in accordance with the registration and configuration previously executed in box 5210 and box 5215.

[0132] FIG. 6 is a flowchart of a method according to various examples. FIG. 6 illustrates activities on a WD associated with paging operation. In FIG. 6, the WD attempts to receive an alert signal that is transmitted by a paging-hub WD included in the same paging group. As such, FIG. 6 can be intra-related to the method of FIG. 4. For example, FIG. 5 may illustrate activities of the WD 121 of the communication system 100 of FIG. 3.

[0133] The WD executing the method in FIG. 6 operates in the sleep mode. I.e., a data connection is not established between the WD and the cellular network. Accordingly, upon downlink data being scheduled for delivery to the WD (other trigger criteria also conceivable), the cellular network attempts to page the WD. This is to trigger a reconnection attempt by the WD to the cellular network. At box 5305, the WD provides, to the cellular network, an indication that it is capable of being part in a paging group. The capability is at least indicative of the WD being able to receive the alert signal. The capability may additionally include one or more of the following, (i) Capability of the WD to act as a paging-hub WD. (ii) Capability of the WD to monitor paging occasions on behalf of one or more other UEs. (iii) Capability of the WD to transmit the alert signal.

[0134] At box 5310, the paging group is setup. Box 5310 corresponds to box 5210. Similar techniques as explained in connection with box 5210 also apply for box 5310.

[0135] At box 5315, the WD obtains configuration information required for attempting to receive the alert signal. Similar configuration information as previously discussed in connection with box 5215 may be obtained.

[0136] At box 5320, it is determined whether the paging operation based on the alert signal commences. If not, then the legacy operation continues, e.g., as explained in connection with FIG. 2. This means that the WD will monitor paging occasions associated with its network-level paging identity. Else, the WD can suspend monitoring the paging occasion assigned to its own network-level paging identity (at least until receiving the alert signal).

[0137] At box 5325, the WD deactivates its receiver circuitry, e.g., as low-power receiver and main receiver. At optional box 5330 it is determined whether the alert signal is expected, e.g., based on timing information provided as part of the configuration of box 5315. This corresponds to DRX operation. Box 5325 and box 5330 are optional; these boxes 5325 and 5330 are only executed in case DRX is employed. DRX operation is generally optional. The WD may alternatively continuously attempt to receive, i.e., monitor for the alert signal, e.g., using the low- power receiver.

[0138] As a general rule, in the disclosure of the subject application, continuously attempting to receive the alert signal can mean that the respective receiver circuitry, i.e., the low-power receiver, is always-on. Continuously attempting to receive the alert signal is different to a DRX operation in which the receiver circuitry of the low-power receiver is intermittently transitioned into an inactive state; i.e., a duty cycle is employed for attempting to receive the alert signal with phases in which the WD does not listen for the alert signal. As a general rule, the power consumption of the WD tends to be higher when continuously attempting to receive the alert signal, because the low-power receiver is continuously operated in the active state which, in turn, is associated with a higher power consumption than the inactive state used for DRX operation. On the other hand, when continuously attempting to receive the alert signal, it is not required to be aware of or take into account a specific timing at which the alert signal is transmitted. This is because the WD always listens for the alert signal without interruptions.

[0139] Continuously attempting to receive the alert signal can mean without any interruptions or in an ongoing manner. DRX operation can pertain to repetitively listening in an ongoing manner during ON durations that are interrupted by OFF durations.

[0140] The WD attempts to receive the alert signal at box 5335. At box 5340, it is determined whether the alert signal has been received. If the alert signal has been received from the paging-hub WD of the paging group, the method commences at box 5345. At box 5345, one or more subsequent actions are taken. For instance, a main receiver may be transitioned from the inactive state to the active state. For instance, the WD may perform a RACH procedure in order to attempt establishing a connection with the cellular network. It would also be possible that the WD attempts to establish a sidelink connection to another WD, e.g., the WD having transmitted the alert signal. It would also be possible that the WD attempts to receive a paging indicator and a paging message at a subsequent paging occasion associated with its network-level paging identity.

[0141] In particular, the WD may directly perform an attempt to establish the connection with the cellular network if the alert signal unambiguously identifies the WD (cf. TAB. 3). This may be based, e.g., on the network-level paging identity of the WD. It may also be based on a group- level paging identity of the WD. The alert signal may be transmitted a time-frequency resource is uniquely allocated to the WD. On the other hand, if the alert signal does not unambiguously identify the WD, the WD may preferably commence to monitor its paging occasion to determine whether the cellular network is indeed paging the WD.

[0142] In another example, instead of connecting to the cellular network, the WD may also attempt to connect to the paging-hub WD that has transmitted the alert signal. For instance, a multi-hop connection may be established. A sidelink connection may be established.

[0143] At box 3545, responsive to receiving the alert signal, the WD may initiate backscattering for connecting to the cellular network or the first WD.

[0144] Above, a scenario has been disclosed in which the WD attempts to receive the alert signal. As previously explained, in some scenarios, the alert signal may mimic a legacy wake-up signal that is conventionally transmitted by the cellular network. In such scenario, the switch from (i) the cellular network transmitting the WUS to (ii) the paging-hub WD transmitting the alert signal mimicking this WUS may be fully transparent to the WD. In such case, the decision making at box 5320 may not be required.

[0145] FIG. 7 is a flowchart of a method according to various examples. FIG. 7 illustrates activities at a mobility control node associated with paging operation. For instance, FIG. 7 may be executed by a mobility-control node of the core network of the cellular network. For instance, the method of FIG. 7 may be executed by the mobility control node 132 depicted in FIG. 3.

[0146] At box 5405, a registry entry is maintained for a first WD registered at the cellular network. At box 5410, a registry entry is maintained for a second WD registered at the cellular network. The registry entries maintained at box 5405 and box 5410 may include network-level paging identities of the WDs. These entries may indicate whether the respective WD currently operates in the connected mode or the sleep mode.

[0147] Then, it is determined at box 5415 whether a paging group is established. If a paging group is established, a registry entry for the paging group is maintained, at box 5420. This can take various forms. For instance, pointers to the paging group (e.g., being indicative of a paging group identity) can be included in each of the registry entries maintained at box 5405 and box 5410. It would also be possible to create a new registry entry that includes pointers to the registry entries maintained at box 5405, 5410. For instance, a registry entry may be created that includes the paging group identity and includes pointers to the network-level paging identity is associated with each of the first WD and the second WD that are both included in the paging group.

[0148] All entries of boxes 5405, 5410, 5420 can be synchronized in terms of the tracking area for paging. This is under the assumption that WDs of the same paging group collaborating in paging are co-located.

[0149] The registry entries at box 5405 and box 5410 may specify a timeout timer (maximum delay) between transmission of a paging signal until the RRC connection resume is complete. It is possible that one or more such connection establishment timeout timers associated with an allowable delay between paging and connection establishment are adjusted. This takes into account that the one or more paging signals may not directly received by the WDs, but rather mediated by the paging-hub WD.

[0150] Then, at box 5425 it is determined whether the DL data is available for a WD associated with the paging group, e.g., for the first WD or the second WD (other paging triggers are conceivable, e.g., an update procedure). It is also determined whether the respective WD operates in the sleep mode in which the data connection is not established. In the affirmative, paging is triggered.

[0151] Paging is triggered based on the registry entries maintained at box 5425, as well as box 5405 and / or box 5410. For instance, the paging trigger may be indicative of the paging group identity. The paging trigger may be indicative of the network-level paging identity of the paginghub WD of the paging group. The paging trigger may also be indicative of the network-level paging identity of the WD being paged. The paging trigger may include instructions for the BS regarding which paging occasion to use (cf. TAB. 1) and / or which paging identity to use (cf. TAB. 3).

[0152] FIG. 8 is a signaling diagram. FIG. 8 illustrates aspects with respect to the registration and configuration phase for registering and configuring the paging group 120. Aspects of FIG. 8 may implement box 5205, box 5210, and box 5215 of the method of FIG. 5. Aspects of FIG. 8 may implement box 5305, box 5310, and box 5315 of the method of FIG. 6. Aspects of FIG. 8 may implement box 5420 of the method of FIG. 7.

[0153] At 3005, the WD 121 registers to the cellular network 130. The WD 121 indicates that it is capable to offload its paging to a different device such as another WD. This can be signaled as a capability. 3005 can also indicate which paging-hub WD to sign up to. 3005 accordingly corresponds to box 5305 of FIG. 6.

[0154] At 3010, the paging-hub WD 129 signals its capability to the cellular network 130. 3010 accordingly corresponds to box 5205 of FIG. 5. This can also be termed assistance information.

[0155] This may trigger the cellular network 130 to define a group identity for the paging-hub WD 129.

[0156] Such information is provided to the paging-hub WD 129 at 3015.

[0157] Such group identity of the paging group 120 may be implemented by a 5G-GUTI with TMSI used for decoding the paging identification for all the WDs part of the paging group 120. Authentication to the paging group 120 may be performed in collaboration between the paginghub WD 129 and the cellular network and its network components, e.g., Unified Data Management (UDM), Authentication Server Function (ALISF) and Access and Mobility Management Function (AMF).

[0158] As previously explained, it is not required in all variants that a group identity is used for the paging. An alternative solution would be that the paging-hub WD 129 decodes the paging indicator for all network-level paging identities of all WDs 121-123, 129 belonging to the paging group 120. As indicated in FIG. 8, the cellular network 130 can provide a list of all WDs 121- 123, 129 belonging to the paging group 120 to the paging-hub WD 129 (this list is yet empty at 3015; but if, e.g., UEs 122, 123 were already part of the paging group 120, their paging identity could be signaled). For instance, the network-level paging identities of all WDs included in the paging group can be included in the message communicated at 3015.

[0159] At 3020, a mobility database is updated with information associated with the paging group 120. This enables to jointly track the WDs 121 , 122, 123, 129 of the paging group 120. The mobility database can be managed by a mobility control node of the core network. A respective registry entry may be generated, see box 5420 of FIG. 7.

[0160] At 3025, the serving BS (here BS 132) is provided with such information associated with the paging group 120. This enables the BS 132 to generate paging signals (e.g., paging indicator and paging message) accordingly, e.g., based on a group identity or another identity, and using the appropriate paging occasion (cf. TAB. 1).

[0161] At 3030, a given WD - e.g., the WD 121 - registers to the paging group 120. This may include a subscription request. It may be triggered by an advertisement (e.g., on a sidelink channel) by the WD 129.

[0162] In the scenario of FIG. 8, this registration is provided by the WD 121 to the cellular network 130. Subscriptions to the paging group 120 can thereby be managed by the cellular network 130, e.g., the mobility control node 131. In other scenarios, the registration can be via the paging-hub WD 129.

[0163] As a general rule, the addition of a WD to a paging group may be triggered by the respective WD, another WD of that paging group, or by the cellular network, e.g., based on proximity information of the WDs.

[0164] At 3035, the cellular network 130 confirms that the WD 121 has been added to the paging group 120. The respective message communicated at 3035 instructs the WD 121 to monitor for alerts signals transmitted by the paging-hub WD 129; rather than execute conventional paging operation (cf. FIG. 6: box 5320, “Yes”-path). A sequence design of the alert signal and / or timing information and / or time-frequency resources of the alert signal may be configured.

[0165] As a general rule, the alert signal is different than paging signals such as a paging DCI or a paging message transmitted on shared channel.

[0166] At 3040, the cellular network 130 informs the paging-hub WD 129 that the WD 121 has been added to the group 120 and at the paging-hub WD 129 is to mediate paging of the WD 121 from now on. At 3040, the cellular network 130 provides information regarding alert signal expected by the WD 121 to the paging-hub WD 129. The cellular network 130 provides information regarding which paging occasion to monitor to the paging-hub WD 129. The cellular network 130 provides information regarding which paging identity will be used to signal the WD 121 is being paged. 3040 hence corresponds to FIG. 5, box 5215 and box 5220. In other examples, the WD 121 may provide this information to the paging-hub WD 129 on a sidelink.

[0167] If the paging-hub WD 129 has knowledge of the paging identities of all WDs 121, 122, 123 in the group, the alert signal can include a signature determined based on the paging identity of the WD being paged.

[0168] In other examples, it is not required that the paging-hub WD 129 is aware of the paging identities of the group members. Here, the alert signal may be unspecific for any particular WD and all WDs may then monitor its paging occasion for a subsequent paging signal.

[0169] FIG. 9 is a signaling diagram. FIG. 9 illustrates aspects with execution phase of paging operation. FIG. 9 may follow FIG. 8. After the nodes have been configured the WDs 121, 122, 123, 129 belonging to the paging group 129, the WDs 121, 122, 123 suspend monitoring their own paging occasions. Instead, the WDs 121, 122, 123 attempt to receive the alert signal transmitted by the paging-hub WD 129, e.g., continuously, periodically, using DRX, predefined times, and / or at predefined time-frequency resources.

[0170] Aspects of FIG. 9 may accordingly implement box 5325 through box 5345 of the method of FIG. 6. Aspects of FIG. 9 may accordingly implement the method of FIG. 4.

[0171] At 3105, the paging-hub WD 129 (here employing DRX which is however generally optional; the DRX OFF durations 3199 of the DRX cycle are shown) transitions its receiver into an activate state (cf. box 5115 in FIG. 4) and at 3110 monitors a paging occasion.

[0172] 3110 may optionally include attempting to receive a WUS (cf. FIG. 4: box 5120; only if WUS operation is enabled).

[0173] 3110 may include the paging-hub WD 129 synchronizing to the BS 132 (cf. FIG. 4: box 5135).

[0174] Monitoring the paging occasion includes attempting to receive a paging indicator and a paging message (cf. FIG. 4: box 5140, 5145). Such paging may be indicative of the cellular network paging the paging-hub WD 129 and / or one or more of the remaining WDs 121, 122, 123 of the paging group.

[0175] At 3110, there is no paging signal detected for any of the WDs 121, 122, 123, 129 included in the paging group 120. As discussed in connection with FIG. 5, this can be concluded at any stage of the paging procedure, e.g., at WUS reception (corresponding to box 5025; i.e., the paging-hub WD 129 does not detect the WUS, if used), at paging indicator decoding (corresponding to box 5041; i.e., the paging-hub WD 129 does not detect any paging indicator), or at paging message decoding (corresponding to box 5050; e.g., the paging-hub WD 129 does not detect any paging message indicative of the cellular network 130 paging either the paginghub WD 129 itself or one or more of the other WDs 121, 122, 123 of the paging group 120.).

[0176] At 3115, payload data arrives for the WD 121 from a data network. DL payload data is only one trigger criterion for triggering paging.

[0177] At 3120, the core network 131 provides a paging trigger to the BS 132. This is because the BS 132 is registered as serving BS for the paging group 120 to which the WD 121 belongs. The paging trigger may be indicative of the particular paging identity to use (cf. TAB. 2) and / or may be indicative of the particular paging occasion to use (cf. TAB. 1). The core network 131 , e.g., the mobility-control node 132 determines that the WD 121 is part of the paging group 120. This can be indicated in the paging trigger provided at 3105.

[0178] The BS 132 then transmits the paging indicator 505 at 3135 and at 3140 the paging message 510. These paging signals are indicative of the cellular network 130 paging the WD 121 (or, at least, they are indicative of the cellular network 130 attempting to page one of the WDs in the paging group 120 other than the paging-hub WD 129).

[0179] The paging-hub WD 129 wakes up at 3125 (e.g., triggered by a WUS transmitted by the BS 132; WUS operation is optional, as mentioned above) and monitors the paging occasion at 3130. It receives the paging signals 505, 510 and determines that the WD 121 is being paged (or, at least, that some WD in the paging group other than itself is being paged). For instance, the paging message 510 can include the paging identity of the WD 121. It would also be possible that the paging message 510 includes a group identity of the paging group 120. Some examples regarding the information contained in the paging message 510 and / or the paging indicator 505 have been disclosed above in connection with TAB. 2.

[0180] To wake-up the WD 121 , the paging-hub WD 129 then generates transmits the alert signal 590 at 3145 (cf. FIG. 4: box 5155). The alert signal 590 can be a 3GPP signal or a proprietary signal carried by other type of access technology and a special low-power receiver design. The WD 121 periodically or continuously monitors for potential alert signals. The WD 121 may or may not use DRX operation.

[0181] The WD 121 then detects the alert signal and, at 3150, takes one or more actions (cf. FIG. 6: box 5345) to prepare for data communication. A RACH procedure and a RRC connection resume may be executed. In case the wake-up receiver is proprietary there is a signal and a request into the 3GPP stack to support the wake up and fulfilling the timing between the paging message and data transfer.

[0182] At 3155 the data queued at 3115 can be communicated.

[0183] By such techniques, the power consumption at the WD 121 can be further reduced. The WD 121 does not need to monitor paging occasions.

[0184] For example, in a reference scenario, the WD is located at a cell edge. Signals transmitted from the BS have a relatively low signal-to-noise ratio. This is also true for wake-up signals. A situation may arise where the low-power receiver of the WD is unable to receive wake-up signals. As a result, a fallback to paging operation based on paging signals only is required, resulting in higher power consumption by the WD. Even in such cell edge scenarios, the use of the paging-hub WD can allow the low-power receiver to be used to detect the wakeup signal. Thus, power consumption can be reduced if compared to this reference scenario.

[0185] FIG. 10 schematically illustrates aspects in connection with a WD, here - for illustrative purposes - specifically the WD 121. Other WDs (such as the WDs 122, 123, 129) can be configured similarly. The WD 121 includes a processor 1021 and the memory 1025. The WD 121 also includes a wireless interface 1022 to access the wireless channel. The processor 1021 can control the wireless interface 1022 to transmit signals, receive signals, monitor paging occasions, etc. As illustrated in FIG. 10, it is possible - but not mandatory - that the wireless interface 1022 includes multiple receiver circuitry, here a main receiver 2029 and a low-power receiver 1028. The processor 1021 can load program code from the memory 1025 and execute the program code to perform techniques as disclosed herein, e.g., as discussed in connection with the methods of FIG. 2, FIG. 4, FIG. 5, and FIG. 6. The processor 1012 and the memory 1025 accordingly implement a compute circuitry.

[0186] The low-power receiver may be configured to perform non-coherent demodulation in accordance with the non-coherence modulation scheme, e.g., on-off keying (OOK) or frequency-shift keying (FSK). The low-power receiver may be configured to perform timedomain processing. The low-power receiver may be incapable of performing frequency-domain processing.

[0187] The low-power receiver can have an architecture as disclosed in chapter 7.1.1 of 3GPP TR 38.869 V1.0.0 (2023-09).

[0188] When a time-domain receiver is set to receive OOK modulated signals, it first captures the incoming OOK signal from the channel. This captured signal may undergo front-end processes such as amplification and filtering to eliminate out-of-band noise. The key component of an OOK receiver is a threshold detector. The detector checks the amplitude of the received signal against a predefined threshold. If the signal's amplitude is above this threshold, it is considered as the presence of the carrier, meaning a "1". If below, it's treated as the absence of the carrier, meaning a "0".

[0189] The main receiver 1029 may be configured to perform Orthogonal Frequency Division Multiplex (OFDM) demodulation. This can include Fast Fourier Transformation or generally frequency-domain processing. The main receiver 1029 may be configured to pick-up the transmitted OFDM signal, which comprises of multiple orthogonal subcarriers carrying data simultaneously. The received signal first undergoes front-end processing, including amplification, down-conversion, and filtering. A synchronization process is employed to detect and correct for any timing and frequency offsets. Once synchronized, the cyclic prefix added at the transmitter to mitigate inter-symbol interference is removed. The signal is then passed through a Fast Fourier Transform to convert it from the time domain to the frequency domain. Equalization is performed on each subcarrier to compensate for the frequency-selective fading introduced by the channel. The data symbols on each subcarrier are demodulated, typically using techniques like Quadrature Amplitude Modulation or Phase Shift Keying. Error correction decoding is applied, such as using Turbo codes or Low-Density Parity-Check codes, to rectify errors that occurred during transmission. The bits from all subcarriers are then serially concatenated to recreate the original bitstream. This reconstructed bitstream is then passed to subsequent layers (e.g., the network layer) for further processing and information extraction.

[0190] As a general rule, a WD as disclosed herein may be a smartphone, a smart device such as a smart watch or smart glasses, a cellular phone, an Internet of Things device, etc.

[0191] FIG. 11 schematically illustrates aspects in connection with a mobility control node such as a mobility control node 132 of the core network 131 of the cellular network 130 (cf. FIG. 1). Other control nodes in the core network can be configured similarly. In addition to other control nodes in the core network, also data-plane nodes in the core network can be configured as shown.

[0192] The control node 132 includes a processor 1091 and the memory 1095. The processor 1091 can load program code from the memory 1095 and execute the program code to perform techniques as disclosed herein, e.g., as discussed in connection with FIG. 7. Specifically, the processor 1091 can provide messages to other nodes, e.g., of the radio-access network, via a communication interface 1092; the processor 1091 can also obtain messages from other nodes.

[0193] FIG. 12 schematically illustrates aspects in connection with the base station, here specifically the base station 139. At the base stations can be configured similarly. The base station 139 includes a processor 1011 and the memory 1015. The base station 139 also includes a communication interface 1012 for accessing the wireless channel. The processor 1011 can load program code from the memory 1015 and execute the program code. This causes the processor 1011 to perform techniques as disclosed herein, e.g., obtain a trigger message from a core network and transmit one or more paging signals based on the trigger message.

[0194] FIG. 13 schematically illustrates aspects with respect to the connection between a WD such as the WD 121 and the cellular network 101. Similar aspects likewise apply to each of the other WDs such as the WDs 122, 123, 129. In the example of FIG. 13, the connection between the WD 121 and the cellular network 100 is defined with respect to certain connection modes 281 - 283.

[0195] In a dormant mode 281 , the WD 121 is fully disconnected from the network 101. As such, the network 100 may not be aware of the location of the WD 121. Transmission of UL data and / or of DL data may not be possible. A higher-layer data connection may not be established.

[0196] Upon initialization of the connection with the cellular network 101 , the WD 121 transitions into a connected mode 283. In the connected mode 283, one or more higher-layer data connections such as bearers for communication of the data are established. An end-to-end data connection within the data plane of the cellular network 101 - encompassing one or more gateway nodes of the core network 131 - may have been established. In the connected mode 283, an Internet protocol (IP) address may be assigned to the WD 121. In the connected state 283, it may be possible to transmit UL data and / or DL data. The cellular network 101 may be aware of the location of the WD 121.

[0197] In a sleep mode 282, communication of data between the WD 121 and the cellular network 101 may be restricted. For example, in the sleep mode 282, the cellular network 101 may hold no valid location or routing information for the WD 102. The particular serving BS within which the WD 121 is located may not been known to the cellular network 101. Nonetheless, in the sleep mode 282, some context information of the WD 121 may be accessible to the cellular network 101. For example, the position of the WD 121 may be known at tracking area granularity or not known at all. The cellular network 101 may be aware of whether the WD 121 is part of a paging group. Then, paging of the WD 121 within a tracking area may be possible, e.g., using a paging-escalation strategy that progressively increases the number of cells in which the WD 121 is being paged. This may facilitate connection of the WD 121 to the network 101 , e.g., by setting up an appropriate bearer and / or assigning an IP address to the WD 121. This corresponds to transitioning to the connected mode 283.

[0198] Summarizing, above scenarios have been disclosed that enable a WD to offload monitoring of paging occasions to a paging-hub WD. The WD in the paging-hub WD are part of a paging group. As a general rule, in some scenarios the paging-hub WD may be fixedly assigned to execute the functionality of monitoring one or more paging occasions one or more other WDs included in the paging group. However, in some scenarios, it is also possible that different WDs included in the paging group take turns in monitoring the one or more paging occasions. For instance, a round-robin scheme may be employed. This is shown in FIG. 14.

[0199] FIG. 14 schematically illustrates that the WDs 121, 122, 123, 129 of the paging group 120 alternatingly act as paging-hub WD. Such operation then can reduce the energy consumption, e.g., if compared to the reference energy consumption of Eq. 1.

[0200] The UEs alternatingly monitor the paging occasions. WD n monitors one or more paging occasions in the following timeslots: n + pN, p e Z. During all other timeslots, WD n does not monitor paging occasions. It rather attempts to receive the alert signal using a low power receiver.

[0201] In other words, a given WD monitors paging occasion associated with its paging identity until paging collaboration is activated (this is the reference energy consumption case according to Eq. 1). I.e., it can be determined whether the paging group has been activated. For instance, paging collaboration can be activated by another WD participating in the paging collaboration or by a node of the cellular network. If paging collaboration is not activated, alert signals as disclosed herein are not expected. Collaborative paging includes a first WD operating as paging hub and one or more second WDs attempting to receive paging signals transmitted by the paging hub. Upon collaborative paging being activated, the WD changes its behavior. It then alternates between (i) attempting to receive the alert signal, and (ii) monitoring one or more paging occasion (cf. TAB. 1). This WD behavior is illustrated in FIG. 15.

[0202] FIG. 15 is a flowchart of a method according to various examples. FIG. 15 illustrates actions and method steps for use in a WD associated with paging operation. In FIG. 15, the WD executing the method alternatingly acts (i) as a paging-hub WD for one or more other WDs included in the same paging group as the paging-hub WD; (ii) as a WD attempting to receive the alert signal from another WD in the paging group then acting as the paging-hub WD.

[0203] At optional box 5805, the WD obtains timing information indicative of a timing schedule for alternating between (i) monitoring paging occasions on the one hand and (ii) attempting to receive an alert signal on the other hand. Thus, there are first time durations during which the WD monitors paging occasions and second time durations during which the WD attempts to receive an alert signal; any first time duration is neighboring one or two second time durations. For instance, the timing information may be obtained from the cellular network, e.g., from a mobility control node (cf. FIG. 1 and FIG. 3: mobility control node 132). It would also be possible that the timing information is obtained from another WD participating in the paging collaboration.

[0204] Then, at box 5810, it is determined whether paging collaboration is being activated. I.e., it can be determined whether the paging group has been activated. For instance, paging collaboration can be activated by another WD participating in the paging collaboration or by a node of the cellular network. If paging collaboration has not been activated ("no"-path), conventional paging operation commences, e.g., as previously discussed in connection with FIG. 2. The WD then monitors its paging occasions, i.e., associated with its paging identity, to determine whether the cellular network attempts to page the WD. At this point, the WD does not attempt to receive the activation signal.

[0205] Upon collaborative paging being activated, the method commences at box 5815. Box 5815 is a decision point for alternating between monitoring paging occasions at box 5820 on the one hand and attempting to receive the alert signal on the other hand at box 5825.

[0206] In particular, the WD, box 5815 can determine whether it is currently in a first type of timeslot in which it is delegated to monitor one or more paging occasions (cf. TAB. 1) to determine whether the cellular network pages the WD and / or one or more further WDs participating in the paging collaboration; or can determine whether it is currently in a second type of timeslot in which it is not required to monitor paging occasions, but rather attempt to receive the alert signal.

[0207] When executing box 5820 the WD may execute the method of FIG. 4.

[0208] When executing box 5825, the WD may execute the method of FIG. 6 (from box 5320 onwards). The resulting behavior across all WDs 121, 122, 123, 129 participating in the paging group 120 is illustrated in FIG. 16.

[0209] FIG. 16 illustrates aspects in connection with the timing information 670. The timing information 670 defines multiple time slot 671, 672, 673, 674. In the time slot 671 , the WD 129 executes the functionality of the paging hub. Accordingly, in the time slot 671 , the WD 129 executes box 5820. In the time slot 671 , the WD 129 monitors paging occasions (cf. TAB. 1) to determine whether the cellular network attempts to page the WD 129 and / or any one of the further WDs 121, 122, 123. Upon the WD 129 determining, based on said monitoring of the one or more paging occasions, that the cellular network attempts to page one of the further WDs 121, 122, 123, it transmits the alert signal. The other WDs 121, 122, 123, the time slot 671, attempts to receive the alert signal by executing box 5825.

[0210] FIG. 16 illustrates how the roles are alternated amongst the WDs 121, 122, 123, 129 by switching between executing box 5820 and box 5825.

[0211] FIG. 16 illustrates paging occasion 680 (open circles) and further illustrates paging occasion 681 (full circles). For instance, it would be possible that the paging occasion 680 is associated with the network-level paging identity of the WDs 121 and 122, and that the paging occasion 681 is associated with the network-level paging identity of the WDs 123 and 129. When operating in a mode according to examples 1 and 3 (in combination) of TAB. 1, then each WD 123, 129 - when executing box 5820 - would be required to monitor all paging occasions 680, 681. On the other hand, for a scenario according to TAB. 1: example 1 (only), the cellular network is informed about the timing information 670 aggregates all paging into the paging occasion of the WD currently executing the paging hub functionality; the cellular network then transmits paging for any one of the WDs 121, 122, 123, 129 in the paging occasion 681 during the time slot 671 , in the paging occasion 680 during the time slot 672, in the paging occasion 680 during the time slot 673, and in the paging occasion 681 during the time slot 674. Finally, it would also be possible to define dedicated paging occasions associated with the paging identity of the paging group (not shown in FIG. 16), so that the particular WD 121 , 122, 123, 122 acting as paging hub (executing box 5820) is required to monitor the paging occasion associated with the paging identity of the paging group, only (cf. TAB. 1: example 2). The operation disclosed above can be formalized as follows: During the extended timeslot in which WD n monitors for paging, said WD decodes the paging channel (attempts to receive the paging indicator) and reads the paging message (e.g., on the PDSCH) for all N UEs of the paging group. If WD n detects paging for WD m #= n, it transmits the alert signal; the alert signal may be indicative of the cellular network paging the WD, i.e., may be dedicated for WD m. This, in turn, wakes up WD m . The WD m initiates RACH procedure. Alternatively, WD m wakes up and is expected to monitor a subsequent paging occasion listen for a repetition of a paging message (the radio-access network repeats paging until WD m makes contact). Alternatively, WD n re-transmits the paging message after the WUS, which WD m is expected to listen to.

[0212] It is now possible to calculate the energy consumption per WD during N timeslots. Each WD monitors for paging during one timeslot. This has an associated energy consumption of KEDRX. Here, K > 1 is a factor accounting for the fact that a WD must decode paging for N WDs , and not only for itself. In case of detecting paging of another WD, transmit the alert signal. This has an expected energy consumption, across all N timeslots, of p( ?)EWUS TX, where p(N) is the expected number of paged UEs during each timeslot. Each WD also monitors for the alert signal during the N - 1 timeslot in which the WD does not monitor for paging. This has an associated energy consumption of (N - 1)EWUS,RX.,

[0213] Thus, the total energy consumption per WD across all N timeslot is

[0214] Ei = KDRX+ p( ?)Ewus TX+ (A — 1)EWUS RX.

[0215] (2) Comparing this to the legacy energy consumption according to Eq. 1 , one obtains ssed.

[0216] The term p2can be accurately approximated by 0. This is so since the low power receiver is considerably less power hungry than the main receiver used. A typical main receiver can have a power consumption of around 20 mW. The low-power receiver can be designed with very much lower power consumption, e.g., less than 100x less than the power consumption of the main receiver. p, is a higher value, because the WD has to transmit the alert signal. However, if the WDs of the paging group are in close proximity to each other (e.g., co-located) the output power at transmission can be low. A transmission of 23 dBm with 50 % efficiency is 400 mW, but 0 dBm at 50 % efficiency is only 2 mW.

[0217] This leaves the term p(N) / N. First of all, waking up two UEs using an alert signal is arguably not (much) more energy consuming than waking up a single WD. This is so since, a) the alert signals may be transmitted in superposition as there is a unique bit pattern that may discriminate the alert signals, b) e.g., powering up the power amplifier has a fixed cost, so sending two alert signals in succession would not be twice as energy consuming as transmission of single alert signal. Moreover, the probability of a wakeup is fairly low, and altogether, setting p(N) = 1 is effectively a worst-case scenario unless N is particularly large (e.g., > 100). In words, this means that during each paging occasion, a WD always must wake another WD. This yields,

[0218] Now, K does scale linearly with N, but only depends weakly on N so since most of the power is associated with circuitry and FFT operations, etc. Thus, it can safely be assumed that K is very close to unity.

[0219] FIG. 17 is a flowchart of a method according to various examples. FIG. 17 illustrates activities that may be executed at a mobility control node associated with paging operation. For instance, FIG. 17 may be executed by a mobility-control node of the core network of the cellular network. For instance, the method of FIG. 17 may be executed by the mobility control node 132 depicted in FIG. 3. It would also be possible that the method of FIG. 17 is executed by a WD.

[0220] At box 5905, the node determines and distributes timing information such as the timing information 670. The timing information defines timeslots. Multiple WDs of a paging group engage alternate between (i) monitoring paging occasions, cf. box 5820 in FIG. 15, and (ii) attempting to receive an alert signal, cf. box 5825 in FIG. 15.

[0221] There are various options conceivable for determining the timing information. For instance, the timing information can be determined so that the time slots associated with monitoring paging occasions are allocated to the WDs in a round-robin scheme. Such a scenario is illustrated in FIG. 16. Here, all WDs share a similar fraction of the energy-expensive task of monitoring paging occasions.

[0222] However, it would also be possible to deviate from such equal allocation of the energy- expensive task of the paging-hub functionality.

[0223] For instance, the timing information may be determined depending on one or more properties of the paging group.

[0224] For example, it would be possible that a length of each individual time slot depends on the size of the device group. For instance, it would be possible that the scheme of allocating the paging-hub functionality to the various WDs depends on one or more device types of the WDs included in the paging group.

[0225] For instance, some paging groups may be classified as loT group, e.g., formed by WDs having a particular low energy consumption. Other paging groups may be classified as active device groups, e.g., including active WDs such as smart phones or smart watches. For instance, certain paging groups may be classified as having a hierarchy, i.e. , including a master device (e.g., a smart phone) multiple slave devices (e.g., wearable electronics). For different types of paging groups, different timing information may be determined.

[0226] Alternatively or additionally to such properties of the paging group, it would also be possible to take into account one or more properties of each of the WDs. For instance, WDs having different properties can be treated differently, e.g., sharing a smaller or larger burden of the energy-expensive task of monitoring the paging occasions.

[0227] For example, timeslots associated with the paging-hub functionality being executed by a given WD may be shortened; while timeslots associated with the paging-hub functionality being executed by another WD (e.g., having a large capacity battery or having a battery with high state of charge; and / or being located at a better coverage situation if compared to other WDs) may be lengthened.

[0228] One or more properties of the WDs that can be taken into account for determining the timing information can include one or more of the following: a device category of the respective WD, a master status of the respective WD in a paging group associated with the collaborative paging, a battery state-of-charge of a battery of the respective WD, a capacity of a battery of the respective WD, and / or coverage level of the respective device.

[0229] Summarizing techniques have been disclosed that enable WD aggregation and collaboration on paging. A paging hub (also referred to as paging watchdog, aggregation node, paging hotspot, etc.) reads paging on behalf of multiple WDs and transmits alert signals to those WDs. A group-based paging identity with purpose of WD aggregation can be used.

[0230] The capability of a WD to support paging collaboration can be signaled.

[0231] The alert signal may be a 3GPP or non-3GPP signal.

[0232] The paging groups can be network-controlled or WD-controlled. A user and / or the cellular network can add / remove WDs from the paging group.

[0233] Summarizing, at least the following EXAMPLES have been disclosed above.

[0234] EXAMPLES

[0235] EXAMPLE 1. A method for use in a first wireless device (129) connectable to a cellular network (130), the first wireless device (129) and a second wireless device (121) being included in a paging group (120), the method comprising:

[0236] - monitoring (5140, 5135) a paging occasion to determine whether the cellular network (130) pages the second wireless device (121), and

[0237] - upon determining that the cellular network pages the second wireless device, generating and transmitting (5155) an alert signal (590) for the second wireless device (121).

[0238] EXAMPLE 2. The method of EXAMPLE 1 , wherein the alert signal (590) uniquely identifies the second wireless device (121) at least within the paging group (120).

[0239] EXAMPLE 3. The method of EXAMPLE 1 or 2, wherein the alert signal carries a group-level paging identification of the second wireless device (121).

[0240] EXAMPLE 4. The method of any one of the preceding EXAMPLES, wherein the alert signal (590) is receivable by time-domain processing at the second wireless device (121).

[0241] EXAMPLE 5. The method of any one of EXAMPLES 1 to 4, wherein the paging occasion is associated with a paging identification of the paging group (120).

[0242] EXAMPLE 6. The method of any one of EXAMPLES 1 to 4, wherein the paging occasion associated with a network-level paging identification of the first wireless device (129).

[0243] EXAMPLE 7. The method of any one of the preceding EXAMPLES, further comprising: - obtaining (5125) an indication of at least one of a group identity associated with the paging group 8120), a network-level paging identity of the second wireless device (121), or a group-level paging identity of the second wireless device (121).

[0244] EXAMPLE 8. A method for use in a second wireless device (121) connectable to a cellular network (130), a paging group (120) including the second wireless device (121) and a first wireless device (129), wherein the method comprises:

[0245] - receiving (5535), from the first wireless device (129), an alert signal (590) indicative of the cellular network (130) paging the second wireless device (121).

[0246] EXAMPLE 9. The method of EXAMPLE 8, wherein the alert signal (590) is received using a low-power receiver (1028) of the second wireless device (121), wherein the method further comprises:

[0247] - activating (5345) a main receiver (1029) responsive to receiving the alert signal (590).

[0248] EXAMPLE 10. The method of EXAMPLE 8 or 9, further comprising:

[0249] - prior to the second wireless device (121) being included in the paging group (120): monitoring paging occasions associated with a network-level paging identification of the second wireless device (121), and

[0250] - upon the second wireless device being included in the paging group: at least partially suspending said monitoring of the paging occasions associated with the network-level paging identification of the second wireless device (121).

[0251] EXAMPLE 11. The method of any one of EXAMPLES 8 to 10, further comprising:

[0252] - responsive to receiving the alert signal (590), executing (5345) a random-access procedure for connecting to the cellular network (130) or the first wireless device (129).

[0253] EXAMPLE 12. A method for use in a node (132) of a cellular network (130), wherein the method comprises:

[0254] - maintaining (5045) a first registry entry for a wireless device (121 , 122, 123, 129) connectable to the cellular network (130),

[0255] - maintaining (5425) a second registry entry for a paging group (120) including the wireless device (121, 122, 123, 129), and

[0256] - triggering (5430) paging of the wireless device (121 , 122, 123, 129) based on the first registry entry and the second registry entry.

[0257] Furthermore, at least the following further EXAMPLES have been disclosed (which can be combined with the EXMAPLES described above, to form further EXAMPLES).

[0258] EXAMPLE 1. A method for use in a first wireless device connectable to a cellular network (130), the method comprising:

[0259] - monitoring (5040, 5045) paging occasions (681, 682) associated with a paging identity of the first wireless device (121, 122, 123, 129), and

[0260] - upon collaborative paging being activated for the first wireless device (121, 122, 123, 129) and for one or more second wireless devices (121, 122, 123, 129): alternating (5815) between attempting (5825) to receive an alert signal (590) transmitted by the one or more second wireless devices (121, 122, 123, 129), and monitoring (5820) at least one of the paging occasions (680, 681) or further paging occasions (680, 681) for determining whether the cellular network (130) pages the first wireless device or the one or more second wireless devices.

[0261] EXAMPLE 2. The method of EXAMPLE 1 , wherein the first wireless device (121, 122, 123, 129) continuously attempts to receive the alert signal in between adjacent ones of the at least one of the paging occasions (680, 681) or the further paging occasions (680, 681).

[0262] EXAMPLE 3. The method of EXAMPLE 1 or 2, further comprising:

[0263] - obtaining (5805), from the cellular network (130) or another wireless device (121, 122, 123, 129), timing information (670) for said alternating between attempting to receive the alert signal and monitoring the at least one of the paging occasions or the further paging occasions.

[0264] EXAMPLE 4. A method for use in a node of a cellular network or in a wireless device, the method comprising:

[0265] - determining timing information defining timeslots according to which multiple wireless devices engaging in collaborative paging alternate between monitoring paging occasions for determining whether any one of the wireless devices is being paged, and attempting to receive an alert signal transmitted by another one of the wireless devices.

[0266] EXAMPLE S. The method of EXAMPLE 4, wherein timeslots of the timing information associated with said monitoring of the paging occasions are allocated to the multiple wireless devices using a round-robin scheme.

[0267] EXAMPLE 6. The method of EXAMPLE 4 or 5, wherein said determining of the timing information depends on one or more properties of a paging group associated with the wireless devices.

[0268] EXAMPLE ?. The method of EXAMPLE 6, wherein the one or more properties of the paging group comprise at least one of a number of wireless devices included in the paging group or a category of the paging group.

[0269] EXAMPLE 8. The method of any one of EXAMPLES 4 to 7, wherein said determining of the timing information depends, for each of the multiple wireless devices engaging in the collaborative paging, on one or more properties of the respective wireless device.

[0270] EXAMPLE 9. The method of EXAMPLE 8, wherein the one or more properties of the respective wireless device comprises at least one of a device category of the respective wireless device, a master status of the respective wireless device in a paging group associated with the collaborative paging, a battery state-of- charge of a battery of the respective wireless device, a capacity of a battery of the respective wireless device, a coverage level of the respective device.

[0271] EXAMPLE 10. A first wireless device (121 , 122, 123, 129) connectable to a cellular network (130), the wireless device comprising compute circuitry configured to:

[0272] - monitor (5040, 5045) paging occasions (681, 682) associated with a paging identity of the first wireless device (121, 122, 123, 129), and

[0273] - upon collaborative paging being activated for the first wireless device (121, 122, 123, 129) and for one or more second wireless devices (121 , 122, 123, 129): alternate (5815) between attempting (5825) to receive an alert signal (590) transmitted by the one or more second wireless devices (121 , 122, 123, 129), and monitoring (5820) at least one of the paging occasions (680, 681) or further paging occasions (680, 681) for determining whether the cellular network (130) pages the first wireless device or the one or more second devices.

[0274] EXAMPLE 11. The first wireless device of EXAMPLE 10, wherein the compute circuitry is configured to perform the method of any one of EXAMPLES 1 to 3.

[0275] EXAMPLE 12. An apparatus comprising a compute circuitry configured to:

[0276] - determine timing information defining timeslots according to which multiple wireless devices engaging in collaborative paging alternate between monitoring paging occasions for determining whether any one of the wireless devices is being paged, and attempting to receive an alert signal transmitted by another one of the wireless devices.

[0277] EXAMPLE 13. The apparatus of EXAMPLE 12, wherein the apparatus is a node of a cellular network or a wireless device. EXAMPLE 14. The apparatus of EXAMPLE 12 or 13, wherein the compute circuitry is configured to perform the method of any one of EXAMPLES 4 to 9.

[0278] EXAMPLE 15. A system comprising the first wireless device of EXAMPLE 10 or EXAMPLE 11 and further comprising the apparatus of any one of EXAMPLES 12 to 14.

[0279] Although the invention has been shown and described with respect to certain preferred embodiments, equivalents and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalents and modifications and is limited only by the scope of the appended claims. For illustration, the disclosed techniques can also be applied to ultra-low power loT device, also referred to as energy neutral devices, zero energy devices, ambient loT devices. The motivation for this is that the instantaneous power consumption target for ultra-low power loT devices is in the range of 1 uW to several mW. Therefore, the main receiver of an ambient loT may have the same characteristics as the low-power receiver, i.e., has worse sensitivity level than a normal UE. For its communication with the cellular network, an ambient loT may need assistance from other nodes with more capability. The WD 121 , second WD, can be an ambient loT device. The first WD is an assistance node monitoring for any downlink communication of the second WD. Upon determining that there is a downlink communication, in form of paging or data, for the second wireless communication device, the first WD generates an alert signal, and transmits, to the second wireless device, the alert signal being indicative of the cellular network needs an uplink transmission from the second wireless device or a downlink data is expected to be followed up after alert signal reception. The downlink data is also received initially by the first WD.

Claims

C L A I M S1. A method for use in a first wireless device (129) connectable to a cellular network (130), the first wireless device (129) and a second wireless device (121) being included in a paging group (120), the method comprising:- monitoring (5140, 5135) a paging occasion to determine whether the cellular network (130) pages the second wireless device (121), and- upon determining that the cellular network pages the second wireless device, generating and transmitting (5155) an alert signal (590) for the second wireless device (121).

2. The method of claim 1 , wherein the alert signal (590) uniquely identifies the second wireless device (121) at least within the paging group (120).

3. The method of claim 1 or 2, wherein the alert signal (590) carries a network-level paging identification of the second wireless device (121).

4. The method of any one of the preceding claims, wherein the alert signal carries a group-level paging identification of the second wireless device (121).

5. The method of claim 1, wherein the alert signal (590) does not uniquely identify the second wireless device (121).

6. The method of any one of the preceding claims, wherein the alert signal is associated with the paging group.

7. The method of claim 6, wherein the alert signal carries a group identity of the paging group (120) and / or is transmitted on time-frequency resources reserved for the paging group.

8. The method of any one of any one of claims 1 to 7, wherein the alert signal (590) triggers a random-access procedure executed by the second wireless device (121).

9. The method of any one of claims 1 to 8, wherein the alert signal (590) triggers the second wireless device (121) to monitor a further paging occasion.

10. The method of any one of the preceding claims, wherein the alert signal (590) is designed to be receivable by a low-power receiver (1028) of the second wireless device (121), wherein the alert signal (590) triggers activation of a main receiver (1029) of the second wireless device (121).

11. The method of any one of the preceding claims, wherein the alert signal (590) is a wake-up signal.

12. The method of any one of the preceding claims, wherein the alert signal (590) mimics a network-originating wake-up signal used by the cellular network (130) for waking-up the second wireless device (121).

13. The method of any one of the preceding claims, wherein the alert signal (590) is receivable by time-domain processing at the second wireless device (121).

14. The method of any one of the preceding claims, wherein the alert signal (590) is transmitted on time-frequency resources allocated by the cellular network (130) to the first wireless device 8129) for transmitting the alert signal (590).

15. The method of any one of the preceding claims, wherein the alert signal (590) is transmitted in an unlicensed band.

16. The method of any one of the preceding claims, wherein the alert signal (590) is transmitted before or in a further paging occasion associated with a network-level paging identification of the second wireless device.

17. The method of claim 16, wherein the alert signal (590) is transmitted at a predefined time offset and / or a predefined frequency offset with respect to the further paging occasion or one or more paging signals associated with the further paging occasion.

18. The method of any one of the preceding claims, wherein the alert signal (590) is transmitted on a device-to-device radio channel.

19. The method of any one of the preceding claims, wherein said monitoring of the paging occasion comprises receiving at least one paging signal (505, 510) using a first radio-access technology, wherein the alert signal (590) is transmitted using a second radio-access technology different than the first radio-access technology.

20. The method of any one of the preceding claims,- obtaining (5125), from the cellular network (130) or the second wireless device (121) or another wireless device (122, 123) included in the paging group (120), a configuration for said generating and / or transmitting of the alert signal (590).

21. The method of claim 20, wherein the configuration is indicative of at least one of a timing of transmitting the alert signal, time-frequency resources for transmitting the alert signal, a time offset with respect to a paging occasion associated with a network-level paging identification of the second wireless device, a frequency offset with respect to a paging occasion associated with a network-level paging identification of the second wireless device, a network-level paging identification of the second wireless device, a sequence design of the alert signal, or a modulation scheme of the alert signal.

22. The method of any one of claims 1 to 21 , wherein the paging occasion is associated with a network-level paging identification of the second wireless device (121).

23. The method of any one of claims 1 to 21 , wherein the paging occasion is associated with a paging identification of the paging group (120).

24. The method of any one of claims 1 to 21 ,wherein the paging occasion associated with a network-level paging identification of the first wireless device (129).

25. The method of any one of the preceding claims, further comprising:- providing (5205), to the cellular network (130) or to the second wireless device (121) or to another wireless device (122, 123) included in the paging group (120), an indication of the first wireless device (129) being able to generate and to transmit the alert signal (590).

26. The method of any one of the preceding claims, further comprising:- obtaining (5125) an indication of at least one of a group identity associated with the paging group 8120), a network-level paging identity of the second wireless device (121), or a group-level paging identity of the second wireless device (121).

27. The method of any one of the preceding claims, further comprising:- providing (5210), to at least one of the cellular network (130), the second wireless device (121), or another wireless device (122, 123), a request for establishing or participating in the paging group (120).

28. The method of any one of the preceding claims, further comprising:- obtaining (5210), from the second wireless device (121) or another wireless device (122, 123) included in the paging group, a request for establishing or participating in the paging group (120).

29. The method of any one of the preceding claims, wherein the first wireless device (129) operates in a sleep mode or a connected mode while monitoring the paging occasion.

30. The method of any one of the preceding claims, further comprising:- receiving (5120) a wake-up signal, wherein said monitoring (5140, 5145) of the paging occasion is responsive to receiving the wake-up signal.

31. The method of any one of the preceding claims, further comprising:- monitoring the paging occasion using discontinuous reception operation.

32. The method of any one of the preceding claims, further comprising:- monitoring the paging occasion for determining whether the cellular network pages the first wireless device or one or more further wireless devices included in the paging group in accordance with timing information, the timing information distributing monitoring activity amongst the first wireless device and the one or more further wireless devices.

33. The method of any one of the preceding claims, wherein the paging group (120) is a device-initiated aggregation of collaborating wireless devices (121, 122, 123, 129).

34. The method of any one of the preceding claims, wherein the paging group (120) is used for paging collaboration of multiple wireless devices.

35. A method for use in a second wireless device (121) connectable to a cellular network (130), a paging group (120) including the second wireless device (121) and a first wireless device (129), wherein the method comprises:- receiving (5535), from the first wireless device (129), an alert signal (590) indicative of the cellular network (130) paging the second wireless device (121).

36. The method of claim 35, wherein the alert signal (590) is received using a low-power receiver (1028) of the second wireless device (121), wherein the method further comprises:- activating (5345) a main receiver (1029) responsive to receiving the alert signal (590).

37. The method of claim 35 or 36, further comprising:- prior to the second wireless device (121) being included in the paging group (120): monitoring paging occasions associated with a network-level paging identification of the second wireless device (121), and- upon the second wireless device being included in the paging group: at least partially suspending said monitoring of the paging occasions associated with the network-level paging identification of the second wireless device (121).

38. The method of any one of claims 35 to 37, further comprising:- responsive to receiving the alert signal (590), executing (5345) a random-access procedure for connecting to the cellular network (130) or the first wireless device (129).

39. The method of any one of claims 35 to 38, further comprising:- responsive to receiving the alert signal (590), initiating backscattering for connecting to the cellular network (130) or the first wireless device (129).

40. The method of any one of claims 35 to 39, further comprising:- attempting to receive the alert signal using either discontinuous reception operation or continuous reception operation.

41. The method of any one of claims 35 to 40, further comprising:- attempting to receive the alert signal in accordance with timing information obtained from at least one of the first wireless device or the cellular network or another wireless device included in the paging group.

42. The method of any one of claims 35 to 40, further comprising:- attempting to receive the alert signal in accordance in resources indicated by at least one of the first wireless device or the cellular network or another wireless device included in the paging group.

43. A method for use in a node (132) of a cellular network (130), wherein the method comprises:- maintaining (5045) a first registry entry for a wireless device (121 , 122, 123, 129) connectable to the cellular network (130),- maintaining (5425) a second registry entry for a paging group (120) including the wireless device (121, 122, 123, 129), and- triggering (5430) paging of the wireless device (121 , 122, 123, 129) based on the first registry entry and the second registry entry.

44. The method of claim 43 wherein said triggering of the paging comprises providing information of a paging occasion to be used for transmitting one or more paging signals (505, 510) based on the second registry entry.

45. The method of claim 43 or 44, further comprising:- synchronizing updates of a tracking area stored in the first registry entry and stored in the second registry entry.

46. The method of any one of claims 43 to 45, further comprising:- upon establishing the second registry entry, updating a connection establishment timeout timer in the first registry entry.

47. The method of any one of claims 43 to 46, wherein the node is a mobility management node in a core of the cellular network.

48. A first wireless device connectable to a cellular network, the first wireless device and a second wireless device being included in a paging group, the first wireless device comprising compute circuitry configured to:- monitor a paging occasion to determine whether the cellular network pages the second wireless device, and- upon determining that the cellular network pages the second wireless device, generate and transmit an alert signal for the second wireless device.

49. The first wireless device of claim 48, wherein the compute circuitry is configured to perform the method of any one of claims 1 to 34.

50. A second wireless device connectable to a cellular network, a paging group including the second wireless device and a first wireless device, the second wireless device comprising compute circuitry configured to:- receive, from the first wireless device, an alert signal indicative of the cellular network paging the second wireless device.

51. The first wireless device of claim 50, wherein the compute circuitry is configured to perform the method of any one of claims 35 to 42.

52. A node of a cellular network, the node comprising compute circuitry configured to:- maintain (5045) a first registry entry for a wireless device (121 , 122, 123, 129) connectable to the cellular network (130),- maintain (5425) a second registry entry for a paging group (120) including the wireless device (121 , 122, 123, 129), and- trigger (5430) paging of the wireless device (121 , 122, 123, 129) based on the first registry entry and the second registry entry.

53. The node of claim 52, wherein the compute circuitry is configured to perform the method of any one of claims 43 to 47.

54. A system comprising the first wireless device of claim 48 or 49 and further comprising the second wireless device of claim 50 or 51.

55. A system comprising the first wireless device of claim 48 or 49 and further comprising the second wireless device of claim 50 or 51 and further comprising the node of claim 52 or 53.

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