Signaling to support on-demand system information block type one

Abstract

Disclosed is a method performed by a central unit, the method comprising: receiving, from a first distributed unit controlling a first cell or from a second distributed unit controlling a second cell, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1, of the second cell; broadcasting the configuration information associated with the wake-up signal via the first distributed unit or via the second distributed unit; and transmitting, to the second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

Description

SIGNALING TO SUPPORT ON-DEMAND SYSTEM INFORMATION BLOCK TYPE ONETECHNICAL FIELD

[0001] The following example embodiments relate to wireless communication.BACKGROUND

[0002] As energy resources are limited, it is desirable to improve the energy efficiency of wireless communication networks.SUMMARY

[0003] The scope of protection sought for various example embodiments is set out by the claims. The example embodiments and features, if any, described in this specification that do not fall under the scope of the claims are to be interpreted as examples useful for understanding various embodiments.

[0004] According to an aspect, there is provided a first central unit controlling a first cell, the first central unit comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the first central unit at least to: receive, from a second central unit controlling a second cell, a request to broadcast configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 , of the second cell; and based on receiving the request, broadcast the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell.

[0005] According to another aspect, there is provided a second central unit controlling a second cell, the second central unit comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the second central unit at least to: transmit, to a first central unit controlling a first cell, a request to broadcast configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 , of the second cell; and transmit, to a second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

[0006] According to another aspect, there is provided a second distributed unit controlling a second cell, the second distributed unit comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the second distributed unit at least to: receive, from a second central unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand system information block type one, SIB1 , transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell; and update, based on the request, the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell.

[0007] According to another aspect, there is provided a first central unit controlling a first cell, the first central unit comprising: means for receiving, from a second central unit controlling a second cell, a request to broadcast configuration information associated with a wake-up signal for requesting an on-demand system information blocktype one, SIB1 , of the second cell; and means for broadcasting, based on receiving the request, the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell.

[0008] According to another aspect, there is provided a second central unit controlling a second cell, the second central unit comprising: means for transmitting, to a first central unit controlling a first cell, a request to broadcast configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 , of the second cell; and means for transmitting, to a second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

[0009] According to another aspect, there is provided a second distributed unit controlling a second cell, the second distributed unit comprising: means for receiving, from a second central unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand system information block type one, SIB1 , transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell; and means for updating, based on the request, the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell.

[0010] According to another aspect, there is provided a method performed by a first central unit controlling a first cell, the method comprising: receiving, from a second central unit controlling a second cell, a request to broadcast configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 , of the second cell; and based on receiving the request, broadcasting the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell.

[0011] According to another aspect, there is provided a method performed by a second central unit controlling a second cell, the method comprising: transmitting, to a first central unit controlling a first cell, a request to broadcast configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 , of the second cell; and transmitting, to a second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

[0012] According to another aspect, there is provided a method performed by a second distributed unit controlling a second cell, the method comprising: receiving, from a second central unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand system information block type one, SIB1, transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell; and updating, based on the request, the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell.

[0013] According to another aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by a first central unit controlling a first cell, cause the first central unit to perform at least the following: receiving, from a second central unit controlling a second cell, a request to broadcast configuration information associated with a wake-up signal for requesting an on-demand system information blocktype one, SIB1 , of the second cell; and based on receiving the request, broadcasting the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell.

[0014] According to another aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by a second central unit controlling a second cell, cause the second central unit to perform at least the following: transmitting, to a first central unit controlling a first cell, a request to broadcast configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 , of the second cell; and transmitting, to a second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

[0015] According to another aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by a second distributed unit controlling a second cell, cause the second distributed unit to perform at least the following: receiving, from a second central unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand system information block type one, SIB1, transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell; and updating, based on the request, the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell.

[0016] According to another aspect, there is provided a computer program comprising instructions which, when executed by a first central unit controlling a first cell, cause the first central unit to perform at least the following: receiving, from a second central unit controlling a second cell, a request to broadcast configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1, of the second cell; and based on receiving the request, broadcasting the configuration information associated with the wakeup signal for requesting the on-demand SIB1 of the second cell.

[0017] According to another aspect, there is provided a computer program comprising instructions which, when executed by a second central unit controlling a second cell, cause the second central unit to perform at least the following: transmitting, to a first central unit controlling a first cell, a request to broadcast configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1, of the second cell; and transmitting, to a second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

[0018] According to another aspect, there is provided a computer program comprising instructions which, when executed by a second distributed unit controlling a second cell, cause the second distributed unit to perform at least the following: receiving, from a second central unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand system information block type one, SIB1 , transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell; and updating, based on the request, the master information block of the second cell to indicate at least one of:that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell.

[0019] According to another aspect, there is provided a central unit comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the central unit at least to: receive, from a first distributed unit controlling a first cell or from a second distributed unit controlling a second cell, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 , of the second cell; broadcast the configuration information associated with the wake-up signal via the first distributed unit or via the second distributed unit; and transmit, to the second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

[0020] According to another aspect, there is provided a first distributed unit controlling a first cell, the first distributed unit comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the first distributed unit at least to: receive, from a central unit, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SI B1 , of a second cell; and broadcast the configuration information on the first cell.

[0021] According to another aspect, there is provided a second distributed unit controlling a second cell, the second distributed unit comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the second distributed unit at least to: receive, from a central unit, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand system information block type one, SIB1, transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell; and update, based on the request, the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell.

[0022] According to another aspect, there is provided a central unit comprising: means for receiving, from a first distributed unit controlling a first cell or from a second distributed unit controlling a second cell, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1, of the second cell; means for broadcasting the configuration information associated with the wake-up signal via the first distributed unit or via the second distributed unit; and means for transmitting, to the second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

[0023] According to another aspect, there is provided a first distributed unit controlling a first cell, the first distributed unit comprising: means for receiving, from a central unit, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 , of a second cell; and means for broadcasting the configuration information on the first cell.

[0024] According to another aspect, there is provided a second distributed unit controlling a second cell, the second distributed unit comprising: means for receiving, from a central unit, a request for updating a master information blockof the second cell to indicate at least one of: that an on-demand system information block type one, SIB1 , transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell; and means for updating, based on the request, the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell.

[0025] According to another aspect, there is provided a method performed by a central unit, the method comprising: receiving, from a first distributed unit controlling a first cell or from a second distributed unit controlling a second cell, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 , of the second cell; broadcasting the configuration information associated with the wake-up signal via the first distributed unit or via the second distributed unit; and transmitting, to the second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

[0026] According to another aspect, there is provided a method performed by a first distributed unit controlling a first cell, the method comprising: receiving, from a central unit, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1, of a second cell; and broadcasting the configuration information on the first cell.

[0027] According to another aspect, there is provided a method performed by a second distributed unit controlling a second cell, the method comprising: receiving, from a central unit, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand system information block type one, SIB1 , transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell; and updating, based on the request, the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell.

[0028] According to another aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by a central unit, cause the central unit to perform at least the following: receiving, from a first distributed unit controlling a first cell or from a second distributed unit controlling a second cell, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 , of the second cell; broadcasting the configuration information associated with the wake-up signal via the first distributed unit or via the second distributed unit; and transmitting, to the second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

[0029] According to another aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by a first distributed unit controlling a first cell, cause the first distributed unit to perform at least the following: receiving, from a central unit, configuration information associated with a wakeup signal for requesting an on-demand system information block type one, SIB1 , of a second cell; and broadcasting the configuration information on the first cell.

[0030] According to another aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by a second distributed unit controlling a second cell, cause the second distributed unit to perform at least the following: receiving, from a central unit, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand system information block type one, SIB1 , transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell; and updating, based on the request, the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell.

[0031] According to another aspect, there is provided a computer program comprising instructions which, when executed by a central unit, cause the central unit to perform at least the following: receiving, from a first distributed unit controlling a first cell or from a second distributed unit controlling a second cell, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1, of the second cell; broadcasting the configuration information associated with the wake-up signal via the first distributed unit or via the second distributed unit; and transmitting, to the second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

[0032] According to another aspect, there is provided a computer program comprising instructions which, when executed by a first distributed unit controlling a first cell, cause the first distributed unit to perform at least the following: receiving, from a central unit, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 , of a second cell; and broadcasting the configuration information on the first cell.

[0033] According to another aspect, there is provided a computer program comprising instructions which, when executed by a second distributed unit controlling a second cell, cause the second distributed unit to perform at least the following: receiving, from a central unit, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand system information block type one, SIB1, transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell; and updating, based on the request, the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell.

[0034] According to another aspect, there is provided a user device comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the user device at least to: receive, from a first cell or from a second cell, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 of the second cell; receive, from the first cell or from the second cell, duration information indicating a validity duration of the configuration information associated with the wake-up signal; transmit the wake-up signal based on the configuration information and within the validity duration, wherein the wake-up signal indicates an identifier associated with the second cell; and receive the on- demand SIB1 of the second cell from the first cell or from the second cell.

[0035] According to another aspect, there is provided a user device comprising: means for receiving, from a first cell or from a second cell, configuration information associated with a wake-up signal for requesting an on-demand systeminformation block type one, SIB1 of the second cell; means for receiving, from the first cell or from the second cell, duration information indicating a validity duration of the configuration information associated with the wake-up signal; means for transmitting the wake-up signal based on the configuration information and within the validity duration, wherein the wake-up signal indicates an identifier associated with the second cell; and means for receiving the on- demand SIB1 of the second cell from the first cell or from the second cell.

[0036] According to another aspect, there is provided a method comprising: receiving, from a first cell or from a second cell, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 of the second cell; receiving, from the first cell or from the second cell, duration information indicating a validity duration of the configuration information associated with the wake-up signal; transmitting the wake-up signal based on the configuration information and within the validity duration, wherein the wake-up signal indicates an identifier associated with the second cell; and receiving the on-demand SIB1 of the second cell from the first cell or from the second cell.

[0037] According to another aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by a user device, cause the user device to perform at least the following: receiving, from a first cell or from a second cell, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 of the second cell; receiving, from the first cell or from the second cell, duration information indicating a validity duration of the configuration information associated with the wake-up signal; transmitting the wake-up signal based on the configuration information and within the validity duration, wherein the wake-up signal indicates an identifier associated with the second cell; and receiving the on- demand SIB1 of the second cell from the first cell or from the second cell.

[0038] According to another aspect, there is provided a computer program comprising instructions which, when executed by a user device, cause the user device to perform at least the following: receiving, from a first cell or from a second cell, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 of the second cell; receiving, from the first cell or from the second cell, duration information indicating a validity duration of the configuration information associated with the wake-up signal; transmitting the wake-up signal based on the configuration information and within the validity duration, wherein the wake-up signal indicates an identifier associated with the second cell; and receiving the on-demand SIB1 of the second cell from the first cell or from the second cell.BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In the following, various example embodiments will be described in greater detail with reference to the accompanying drawings, in whichFIG. 1 illustrates an example of a wireless communication network;FIG. 2A illustrates an example of a system;FIG. 2B illustrates an example of a system;FIG. 3 illustrates a signal flow diagram;FIG. 4 illustrates a signal flow diagram;FIG. 5 illustrates a signal flow diagram;FIG. 6 illustrates a signal flow diagram;FIG. 7 illustrates a signal flow diagram;FIG. 8 illustrates a signal flow diagram;FIG. 9 illustrates a signal flow diagram;FIG. 10 illustrates a signal flow diagram;FIG. 11 illustrates a signal flow diagram;FIG. 12 illustrates a flow chart;FIG. 13 illustrates a flow chart;FIG. 14 illustrates a flow chart;FIG. 15 illustrates a flow chart;FIG. 16 illustrates a flow chart;FIG. 17 illustrates a flow chart;FIG. 18 illustrates a flow chart;FIG. 19 illustrates an apparatus; and FIG. 20 illustrates an apparatus.DETAILED DESCRIPTION

[0040] The following embodiments are exemplifying. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments within the scope of the claims. Furthermore, the words "comprising" and "including" should be understood as not limiting the described embodiments to consist of only those features that have been mentioned, and such embodiments may also contain features that have not been specifically mentioned. Reference numbers, in the description and / or in the claims, serve to illustrate the embodiments with reference to the drawings, without limiting the embodiments to these examples only.

[0041] Some example embodiments described herein may be implemented in a wireless communication network comprising a radio access network based on one or more of the following radio access technologies (RATs): global system for mobile communications (GSM) or any other second generation (2G) radio access technology, universal mobile telecommunication system (UMTS, 3G) based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), long term evolution (LTE), LTE-Advanced, fourth generation (4G), fifth generation (5G), 5G new radio (NR), 5G-Advanced (i.e., 3GPP NR Rel-18 and beyond), or sixth generation (6G). Some examples of radio access networks include the universal mobile telecommunications system (UMTS) radio access network (UTRAN), the evolved universal terrestrial radio access network (E-UTRA), or the next generation radio access network (NG-RAN). The wireless communication network may further comprise a core network, and some example embodiments may also be applied to network functions of the core network.

[0042] It should be noted that the embodiments are not restricted to the wireless communication network given as an example, but a person skilled in the art may also apply the solution to other wireless communication networks or systems provided with necessary properties. For example, some example embodiments may also be applied to acommunication system based on IEEE 802.11 specifications, or a communication system based on IEEE 802.15 specifications. IEEE is an abbreviation for the Institute of Electrical and Electronics Engineers.

[0043] FIG. 1 depicts an example of a simplified wireless communication network showing some physical and logical entities. The connections shown in FIG. 1 may be physical connections or logical connections. It is apparent to a person skilled in the art that the wireless communication network may also comprise other physical and logical entities than those shown in FIG. 1.

[0044] The example embodiments described herein are not, however, restricted to the wireless communication network given as an example but a person skilled in the art may apply the example embodiments described herein to other wireless communication networks provided with necessary properties.

[0045] The example wireless communication network shown in FIG. 1 includes a radio access network (RAN) and a core network 110.

[0046] FIG. 1 shows user equipment (UE) 100, 102 configured to be in a wireless connection on one or more communication channels in a radio cell with one or more access nodes 104, 104B of a radio access network.

[0047] The access node 104, 104B may comprise a computing device configured to control the radio resources of the access node 104, 104B and to be in a wireless connection with one or more UEs 100, 102. The access node 104, 104B may also be referred to as a base station, a base transceiver station (BTS), an access point, a cell site, a network node, a radio access network node, or a RAN node.

[0048] The access node 104, 104B may be, for example, an evolved NodeB (abbreviated as eNB or eNodeB), or a next generation evolved NodeB (abbreviated as ng-eNB), or a next generation NodeB (abbreviated as gNB or gNodeB), providing the radio cell. The access node 104, 104B may include or be coupled to transceivers. From the transceivers of the access node 104, 104B, a connection may be provided to an antenna unit that establishes a bidirectional radio link to one or more UEs 100, 102. The antenna unit may comprise an antenna or antenna element, or a plurality of antennas or antenna elements.

[0049] The wireless connection (e.g., radio link) from a UE 100, 102 to the access node 104, 104B may be called uplink (UL) or reverse link, and the wireless connection (e.g., radio link) from the access node 104, 104B to the UE 100, 102 may be called downlink (DL) or forward link. A UE 100 may also communicate directly with another UE 102, and vice versa, via a wireless connection generally referred to as a sidelink (SL). It should be appreciated that the access node 104, 104B or its functionalities may be implemented by using any node, host, server, access point or other entity suitable for providing such functionalities.

[0050] The radio access network may comprise more than one access node, in which case the access nodes 104, 104B may also be configured to communicate with one another over wired or wireless links. These links between access nodes may be used for sending and receiving control plane signaling and also for routing data from one access node to another access node.

[0051] The access node 104, 104B may further be connected to a core network (CN) 110. The core network 110 may comprise an evolved packet core (EPC) network and / or a 5thgeneration core network (5GC). The EPC may comprise network entities, such as a serving gateway (S-GW for routing and forwarding data packets), a packet data network gateway (P-GW) for providing connectivity of UEs to external packet data networks, and / or a mobility management entity (MME). The 5GC may comprise one or more network functions, such as at least one of: a userplane function (UPF), an access and mobility management function (AMF), a location management function (LMF), and / or a session management function (SMF).

[0052] The core network 110 may also be able to communicate with one or more external networks 113, such as a public switched telephone network or the Internet, or utilize services provided by them. For example, in 5G wireless communication networks, the UPF of the core network 110 may be configured to communicate with an external data network via an N6 interface. In LTE wireless communication networks, the P-GW of the core network 110 may be configured to communicate with an external data network.

[0053] It should also be understood that the distribution of functions between core network operations and access node operations may differ in future wireless communication networks compared to that of the LTE or 5G, or even be non-existent.

[0054] The illustrated UE 100, 102 is one type of an apparatus to which resources on the air interface may be allocated and assigned. The UE 100, 102 may also be called a wireless communication device, a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, a terminal device, or a user device, just to mention but a few names. In this description, the terms “user device” and “UE” may be used interchangeably.

[0055] The UE 100, 102 may be a computing device operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of computing devices: a mobile phone, a smartphone, a personal digital assistant (PDA), a handset, a computing device comprising a wireless modem (e.g., an alarm or measurement device, etc.), a laptop computer, a desktop computer, a tablet, a game console, a notebook, a multimedia device, a reduced capability (RedCap) device, a wearable device (e.g., a watch, earphones or eyeglasses) with radio parts, a sensor comprising a wireless modem, or a computing device comprising a wireless modem integrated in a vehicle.

[0056] It should be appreciated that the UE 100, 102 may also be a nearly exclusive uplink-only device, of which an example may be a camera or video camera loading images or video clips to a network. The UE 100, 102 may also be a device having capability to operate in an Internet of Things (loT) network, which is a scenario in which objects may be provided with the ability to transfer data over a network without requiring human-to-human or human-to- computer interaction.

[0057] The wireless communication network may also be able to support the usage of cloud services. For example, at least part of core network operations may be carried out as a cloud service (this is depicted in FIG. 1 by “cloud” 114). The UE 100, 102 may also utilize the cloud 114. In some applications, the computation for a given UE may be carried out in the cloud 114 or in another UE.

[0058] The wireless communication network may also comprise a central control entity, such as a network management system (NMS), or the like. The NMS is a centralized suite of software and hardware used to monitor, control, and administer the network infrastructure. The NMS is responsible for a wide range of tasks such as fault management, configuration management, security management, performance management, and accounting management. The NMS enables network operators to efficiently manage and optimize network resources, ensuring that the network delivers high performance, reliability, and security.

[0059] 5G enables using multiple-input and multiple-output (MIMO) antennas in the access node 104, 104B and / or the UE 100, 102, many more base stations or access nodes than an LTE network (a so-called small cell concept),including macro sites operating in co-operation with smaller stations and employing a variety of radio technologies depending on service needs, use cases and / or spectrum available. 5G wireless communication networks may support a wide range of use cases and related applications including video streaming, augmented reality, different ways of data sharing and various forms of machine-type applications, such as (massive) machine-type communications (mMTC), including vehicular safety, different sensors and real-time control.

[0060] In 5G wireless communication networks, access nodes and / or UEs may have multiple radio interfaces, such as below 6 gigahertz (GHz), centimeter wave (cmWave) and millimeter wave (mmWave), and also being integrable with legacy radio access technologies, such as LTE. Integration with LTE may be implemented, for example, as a system, where macro coverage may be provided by LTE, and 5G radio interface access may come from small cells by aggregation to LTE. In other words, a 5G wireless communication network may support both inter-RAT operability (such as interoperability between LTE and 5G) and inter-RI operability (inter-radio interface operability, such as between below 6GHz, cmWave, and mmWave).

[0061] 5G wireless communication networks may also apply network slicing, in which multiple independent and dedicated virtual sub-networks (network instances) may be created within the same physical infrastructure to run services that have different requirements on latency, reliability, throughput and mobility.

[0062] In one embodiment, an access node 104, 104B may comprise: a radio unit (RU) comprising a radio transceiver (TRX), i.e., a transmitter (Tx) and a receiver (Rx); one or more distributed units (DUs) 105, 105A, 105B that may be used for the so-called Layer 1 (L1) processing and real-time Layer 2 (L2) processing; and a central unit (CU) 108, 108B (also known as a centralized unit) that may be used for non-real-time L2 and Layer 3 (L3) processing. The CU 108, 108B may be connected to the one or more DUs 105, 105A, 105B for example via an F1 interface. Such an embodiment of the access node 104, 104B may enable the centralization of CUs relative to the cell sites and DUs, whereas DUs may be more distributed and may even remain at cell sites. The CU and DU together may also be referred to as baseband or a baseband unit (BBU). The CU and DU may also be comprised in a radio access point (RAP).

[0063] The CU 108, 108B may be a logical node hosting radio resource control (RRC), service data adaptation protocol (SDAP) and / or packet data convergence protocol (PDCP), of the NR protocol stack for an access node 104, 104B. The CU 108, 108B may comprise a control plane (CU-CP), which may be a logical node hosting the RRC and the control plane part of the PDCP protocol of the NR protocol stack for the access node 104, 104B. The CU 108, 108B may further comprise a user plane (CU-UP), which may be a logical node hosting the user plane part of the PDCP protocol and the SDAP protocol of the CU for the access node 104, 104B.

[0064] The DU 105, 105A, 105B may be a logical node hosting radio link control (RLC), medium access control (MAC) and / or physical (PHY) layers of the NR protocol stack for the access node 104, 104B. The operations of the DU 105, 105A, 105B may be at least partly controlled by the CU 108, 108B. It should also be understood that the distribution of functions between the DU 105, 105A, 105B and the CU 108, 108B may vary depending on the implementation.

[0065] Cloud computing systems may also be used to provide the CU 108, 108B and / or DU 105, 105A, 105B. A CU provided by a cloud computing system may be referred to as a virtualized CU (vCU). In addition to the vCU, there may also be a virtualized DU (vDU) provided by a cloud computing system. Furthermore, there may also be acombination, where the DU may be implemented on so-called bare metal solutions, for example application-specific integrated circuit (ASIC) or customer-specific standard product (CSSP) system-on-a-chip (SoC).

[0066] Edge cloud may be brought into the radio access network by utilizing network function virtualization (NFV) and software defined networking (SDN). Using edge cloud may mean access node operations to be carried out, at least partly, in a computing system operationally coupled to a remote radio head (RRH) or a radio unit (RU) of an access node 104, 104B. It is also possible that access node operations may be performed on a distributed computing system or a cloud computing system located at the access node 104, 104B. Application of cloud RAN architecture enables RAN real-time functions being carried out at the radio access network (e.g., in a DU 105, 105A, 105B), and non-real-time functions being carried out in a centralized manner (e.g., in a CU 108, 108B).

[0067] 5G (or new radio, NR) wireless communication networks may support multiple hierarchies, where multi-access edge computing (MEC) servers may be placed between the core network 110 and the access node 104, 104B. It should be appreciated that MEC may be applied in LTE wireless communication networks as well.

[0068] A 5G wireless communication network (“5G network”) may also comprise a non-terrestrial communication network, such as a satellite communication network, to enhance or complement the coverage of the 5G radio access network. For example, satellite communication may support the transfer of data between the 5G radio access network and the core network 110, enabling more extensive network coverage. Possible use cases may include: providing service continuity for machine-to-machine (M2M) or Internet of Things (loT) devices or for passengers on board of vehicles, or ensuring service availability for critical communications, and future railway, maritime, or aeronautical communications. Satellite communication may utilize geostationary earth orbit (GEO) satellite systems, but also low earth orbit (LEO) satellite systems, in particular mega-constellations (i.e., systems in which hundreds of (nano)satellites are deployed). A given satellite 106 in the mega-constellation may cover several satellite-enabled network entities that create on-ground cells. The on-ground cells may be created through an on-ground relay access node or by an access node located on-ground or in a satellite.

[0069] It is obvious for a person skilled in the art that the access node 104, 104B depicted in FIG. 1 is just an example of a part of a radio access network, and in practice the radio access network may comprise a plurality of access nodes 104, 104B, the UEs 100, 102 may have access to a plurality of radio cells, and the radio access network may also comprise other apparatuses, such as physical layer relay access nodes or other entities. At least one of the access nodes may be a Home eNodeB or a Home gNodeB. A Home gNodeB or a Home eNodeB is a type of access node that may be used to provide indoor coverage inside a home, office, or other indoor environment.

[0070] Additionally, in a geographical area of a radio access network, a plurality of different kinds of radio cells as well as a plurality of radio cells may be provided. Radio cells may be macro cells (or umbrella cells) which may be large cells having a diameter of up to tens of kilometers, or smaller cells such as micro-, femto- or picocells. The access node(s) 104, 104B of FIG. 1 may provide any kind of these cells. A cellular radio network may be implemented as a multilayer access networks including several kinds of radio cells. In multilayer access networks, one access node may provide one kind of a radio cell or radio cells, and thus a plurality of access nodes may be needed to provide such a multilayer access network.

[0071] For fulfilling the need for improving performance of radio access networks, the concept of “plug-and-play” access nodes may be introduced. A radio access network, which may be able to use “plug-and-play” access nodes,may include, in addition to Home eNodeBs or Home gNodeBs, a Home Node B gateway (HNB-GW) (not shown in FIG. 1). An HNB-GW, which may be installed within an operator’s radio access network, may aggregate traffic from a large number of Home eNodeBs or Home gNodeBs back to a core network 110 of the operator.

[0072] 6G wireless communication networks are expected to adopt flexible decentralized and / or distributed computing systems and architecture and ubiquitous computing, with local spectrum licensing, spectrum sharing, infrastructure sharing, and intelligent automated management underpinned by mobile edge computing, artificial intelligence, short-packet communication and blockchain technologies. Key features of 6G may include intelligent connected management and control functions, programmability, integrated sensing and communication, reduction of energy footprint, trustworthy infrastructure, scalability and affordability. In addition to these, 6G is also targeting new use cases covering the integration of localization and sensing capabilities into system definition to unifying user experience across physical and digital worlds.

[0073] Given that networks are dimensioned for peak load, and that the number of hours that cells are at peak load may be relatively low, there is a large amount of time where the cells are at low or medium loads. These periods of times, when the cell load is low, are an opportunity for network energy savings (NES). Some techniques for enabling network energy savings may include, for example, SSB-less cells, on-demand SSB, and on-demand system information block type 1 (SIB1).

[0074] An SSB-less cell means that the cell may transition to a mode where it stops broadcasting the synchronization signal block (SSB) based on a predetermined condition being met. This can contribute to reducing the energy consumption of the network, and therefore make the network more sustainable.

[0075] On-demand SSB means that the access node 104, 104B may stop the periodic legacy transmissions of the SSB of the cell, but a UE 100, 102 may request the access node 104, 104B to transmit the SSB of the cell when it is needed.

[0076] On-demand SIB1 (OD-SIB1) means that the access node 104, 104B may stop the periodic legacy transmissions of SIB1 of the cell, but a UE 100, 102 may request the access node 104, 104B to transmit the SIB1 of the cell when it is needed (e.g., by transmitting an uplink signal from the UE 100, 102 to the access node 104, 104B).

[0077] As shown in Table 1 below, there are at least four different solution options for on-demand SIB1 operations, based on which the following functionalities may be distributed between the cell A (or node) and the NES cell (or node): 1) providing the wake-up signal configuration to the UE, 2) UE requesting the on-demand SIB1 transmission using the wake-up signal, and 3) RAN broadcasting the on-demand SIB1 in response to receiving the WUS.

[0078] Cell A refers to a cell that is periodically transmitting at least its own SIB1 according to a legacy procedure (e.g., up to NR Release 18). A UE is able to detect the cell A and camp on it. The cell A may also be referred to as an anchor cell or a first cell herein.

[0079] A NES cell refers to a cell for which an on-demand SIB1 may be transmitted in response to an uplink wakeup signal transmitted from a UE. The NES cell may support switching between on-demand SIB1 and legacy SIB1 operations (i.e., the periodic SIB1 transmission of the legacy procedure can be deactivated or activated as needed). The NES cell may also be referred to as a non-anchor cell or a second cell herein.Table i .

[0080] These solution options are applicable in the cases where the cell A and the NES cell belong to the same DU, or to different DUs in the same access node 104 (e.g., gNB), or to different access nodes 104, 104B (e.g., gNBs).

[0081] FIG. 2A illustrates an example of a wireless communication system, where the cell A 121 and the NES cell 122 are co-located, i.e., controlled by the same access node 104 (e.g., gNB) and sharing the same radio unit. The cell A 121 and the NES cell 122 may be controlled by the same DU 105 of the access node 104, or by different DUs 105, 105A of the access node 104.

[0082] FIG. 2B illustrates an example of a wireless communication system, where the cell A 121 and the NES cell 122 are non-co-located, i.e., the radio units of the cell A and the NES cell are physically non-co-located, and the cells are controlled by different access nodes 104, 104B (e.g., gNBs).

[0083] As can be seen in Table 1, the above solution options assign different roles to the cell A and the NES cell. Hence, in order for these solution options to work, the cell A and the NES cell will have to communicate with each other by sharing certain information. Since these cells could be controlled by the same gNB (co-located cells scenario, and either controlled by the same DU or different DUs) or by different gNBs (non-co-located cells scenario), this may mean different signaling over the Xn and / or F1 interfaces for the above solution options. Without defining such signaling, the solutions will not work.

[0084] Therefore, there is a challenge in how to provide the information exchange between the network nodes at least for the configuration of the wake-up signal for supporting on-demand SIB1 for UEs in idle (RRCJDLE) or inactive (RRCJNACTIVE) mode.

[0085] Some example embodiments relate to the signaling between network entities (e.g., CUs and DUs) for enabling the overall information exchange related to on-demand SIB1. Some example embodiments enable the inter-network- node signaling addressing both the F1 and Xn interfaces.

[0086] In some example embodiments, the WUS configuration and OD-SIB1 information may be owned at the celllevel by DUs, and shared with the CUs over the F1 interface. The CUs may share this information with neighboring CUs over the Xn interface. These configurations may have a validity time duration or period associated with them.

[0087] Some example embodiments also define the Xn and F1 signaling to request for OD-SIB1 activation.

[0088] In some example embodiments, at the time of OD-SIB1 activation, the WUS configuration is broadcasted to the UE before disabling the legacy always-on SIB1. This will ensure that the NES cell is always reachable to the UE in one way or the other. Some example embodiments define the F1 and Xn signaling to enable this.

[0089] Some example embodiments may also provide F1 signaling to enable the CU to request the DU of the NES cell to update the master information block (MIB) to indicate whether the legacy always-on (periodic) SIB1 transmission is disabled or enabled. Alternatively, or additionally, the CU may request the DU to update the MIB to indicate whether the on-demand SIB1 transmission mode is active in the NES cell. The MIB is transmitted in the SSB.

[0090] Furthermore, some example embodiments may provide F1 and Xn signaling to share the WUS configurations (from DU to CU and across CUs).

[0091] Some example embodiments are described below using principles and terminology of 5G radio access technology without limiting the example embodiments to 5G radio access technology, however.

[0092] FIG. 3 illustrates a signal flow diagram according to an example embodiment (corresponding to option 1 of Table 1 above). This example embodiment relates to the scenario of FIG. 2B, where the cell A 121 and the NES cell 122 are non-co-located (i.e., controlled by different access nodes 104, 104B).

[0093] Herein the cell A 121 is referred to as a first cell. The first cell 121 is controlled by a first DU 105, which is controlled by a first CU 108. In other words, the first CU 108 controls the first cell 121 via the first DU 105. The first CU 108 and the first DU 105 may be comprised in a first access node 104 (e.g., a gNB).

[0094] Furthermore, herein the NES cell 122 is referred to as a second cell. The second cell 122 is controlled by a second DU 105B, which is controlled by a second CU 108B. In other words, the second CU 108B controls the second cell 122 via the second DU 105B. The second CU 108B and the second DU 105B may be comprised in a second access node 104B (e.g., a gNB) different from the first access node 104.

[0095] Although only one user device 100 is shown in FIG. 3, it should be noted that the number of user devices may also be different than one. In other words, there may be one or more user devices, and the signaling procedure illustrated in FIG. 3 may be extended and applied according to the actual number of user devices.

[0096] Referring to FIG. 3, at 301, the first DU 105 transmits, to the first CU 108, configuration information associated with a wake-up signal for requesting an on-demand SIB1 of the second cell 122 on the first cell 121. In other words, the configuration information associated with the wake-up signal is intended to be used by a user device 100 to request the on-demand SIB1 of the second cell 122.

[0097] For example, the configuration information may be transmitted over the F1 interface in an F1 setup request message or a DU configuration update request message. In other words, the first DU 105 owns the WUS configuration (identified by an identifier such as PCI) and sends it to the first CU 108 via F1 signaling. The first CU 108 receives the configuration information from the first DU 105.

[0098] At 302, the first CU 108 stores the configuration information for example in an internal memory of the first CU 108.

[0099] At 303, the second CU 108B determines to activate an on-demand SIB1 transmission mode for the second cell 122 controlled by the second CU 108B. Prior to the determination of 303, the second cell 122 may be in a non- on-demand SIB1 operation mode (e.g., transmitting the periodic legacy SIB1 ).

[0100] Alternatively, the second DU 105B may determine to activate the on-demand SIB1 transmission mode for the second cell 122. In this case, the second DU 105B may indicate its activation decision to the second CU 108B over the F1 interface.

[0101] At 304, based on the determination of 303, the second CU 108B transmits, to the first CU 108, a request message indicating that the on-demand SIB1 transmission mode is to be activated for the second cell 122 controlled by the second CU 108B. For example, the request message (e.g., called OD-SIB1 activation request) may be transmitted over the Xn interface. The first CU 108 receives the request message.

[0102] The request message comprises at least duration information indicating a validity duration of the on-demand SIB1 transmission mode for the second cell 122. The validity duration refers to the time duration of how long the on- demand SIB1 transmission mode will remain active or is expected to remain active. In other words, the validity duration comprises a time duration during which the user device 100 is allowed use the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell 122, wherein this time duration relates to the duration during which the second cell uses the on-demand SIB1 mode. The validity duration may also be referred to as a validity time or a validity period.

[0103] The request message may further comprise an identifier such as a physical cell identity (PCI) associated with the second cell 122, a configuration for an on-demand SIB1 procedure towards the second cell 122, and a content of the on-demand SIB1 of the second cell 122. The content and the configuration for the on-demand SIB1 of the second cell 122 may be identifiable by the identifier of the second cell 122.

[0104] The configuration for the on-demand SIB1 procedure may comprise, for example, a radio resource configuration for transmitting the on-demand SIB1. The content of the on-demand SIB1 may comprise SIB1 information elements. In other words, the on-demand SIB1 may comprise the minimum system information needed for initial access to the second cell 122.

[0105] At 305, the first CU 108 transmits, to the user device 100, via the first DU 105, the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell 122 on the first cell 121. In other words, the first CU 108 may transmit the configuration information to the first DU 105, and the first DU 105 may transmit or forward the configuration information to the user device 100 on the first cell 121. For example, the first DU 105 may broadcast the configuration information in a system information block of the first cell 121. The user device 100 receives and stores the configuration information.

[0106] The configuration information indicates one or more conditions related to the wake-up signal (e.g., for transmitting the wake-up signal).

[0107] The configuration information may further comprise the duration information indicating the validity duration of the on-demand SIB1 transmission mode for the second cell 122. Alternatively, the first CU 108 may transmit the duration information separately to the user device 100 (via the first DU 105), and the user device 100 may receive the duration information from the first CU 108 in the separate transmission.

[0108] At 306, the first CU 108 transmits, to the second CU 108B, a response message indicating that the configuration information associated with the wake-up signal has been transmitted to the user device 100. For example, the response message (e.g., called OD-SIB1 activation response) may be transmitted over the Xn interface. The second CU 108B receives the response message.

[0109] At 307, the second CU 108B transmits, to the second DU 105B, a request for updating a master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that an SIB1 transmission (e.g., the periodic legacy SIB1 transmission) is deactivated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105B receives the request.

[0110] At 308, based on the request (or based on its own determination to activate the on-demand SIB1 transmission mode for the second cell 122), the second DU 105B updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122.

[0111] For example, the second DU 105B may update the ssb-SubcarrierOffset information element and the pdcch- ConfigSI B 1 information element in the MIB.

[0112] ssb-SubcarrierOffset corresponds to kSSB, which is the frequency domain offset between SSB and the overall resource block grid in number of subcarriers. For operation with shared spectrum channel access in frequency range one (FR1), this field corresponds to SSB, and kSSB is obtained from SSB. The least significant bit (LSB) of this field may also be used for deriving the quasi-colocation (QCL) relation between SSBs. The value range of this field may be extended by an additional most significant bit encoded within the physical broadcast channel (PBCH). This field may indicate that this cell does not provide SIB1, and that there is hence no control resource set (CORESET) #0 configured in the MIB. In this case, the field pdcch-ConfigSI B1 may indicate the frequency positions where the user device may (not) find an SSB with a control resource set and search space for SIB1.

[0113] pdcch-ConfigSIB1 determines a common CORESET, a common search space and necessary physical downlink control channel (PDCCH) parameters. If the field ssb-SubcarrierOffset indicates that SIB1 is absent, the field pdcch-ConfigSI B 1 may indicate the frequency positions where the user device may find SSB with SIB1, or the frequency range where the network does not provide SSB with SIB1.

[0114] At 309, the second DU 105B stops the SIB1 transmission (broadcast) for the second cell 122 based on updating the master information block, and the second cell 122 enters the on-demand SIB1 transmission mode.

[0115] At 310, the second DU 105B transmits, to the second CU 108B, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The second CU 108B receives the response.

[0116] At 311, the user device 100 detects that the one or more conditions for transmitting the wake-up signal are fulfilled within the validity duration. For example, the one or more conditions for transmitting the wake-up signal may be related to at least one of: one or more radio conditions of the user device 100, or a presence of uplink data to be transmitted from the user device 100.

[0117] The one or more radio conditions refer to the quality of the wireless communication channel between the user device 100 and the network (e.g., the first DU 105 or the second DU 105B). Factors such as signal strength, interference, and noise may affect the one or more radio conditions.

[0118] The presence of uplink data to be transmitted from the user device 100 means that when the user device 100 has data to send in the uplink, the user device 100 may trigger the transmission of the wake-up signal.

[0119] At 312, the user device 100 transmits the wake-up signal to the first DU 105 based on the configuration information and within the validity duration. The first DU 105 monitors for the wake-up signal based on the configuration information, and receives the wake-up signal from the user device 100. The wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122, towards which the user device 100 is requesting the on-demand SIB1 transmission.

[0120] The purpose of the wake-up signal is to trigger the transmission of the on-demand SIB1 transmission of the second cell 122, which is in the on-demand SIB1 transmission mode (i.e., a type of energy-saving state).

[0121] At 313, the first DU 105 transmits or forwards, to the first CU 108, the wake-up signal transmitted from the user device 100, wherein the wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122. For example, the first DU 105 may transmit the wake-up signal to the first CU 108 over the F1 interface. The first CU 108 receives the wake-up signal from the first DU 105.

[0122] At 314, the first CU 108 identifies the configuration and / or the content for the on-demand SIB1 of the second cell 122 based on the identifier comprised in the wake-up signal. In other words, the first CU 108 identifies the OD- SIB1 information from the received PCI and then triggers the transmission of the on-demand SIB1 of the second cell 122.

[0123] At 315, the first CU 108 transmits, to the first DU 105, a request for transmitting the on-demand SIB1 of the second cell 122 to the user device 100 (or for broadcasting the on-demand SIB1 of the second cell 122 on the first cell 121), the request comprising the configuration and the content of the on-demand SIB1 , as identified based on the wake-up signal. For example, the first CU 108 may transmit the request over the F1 interface in a gNB CU configuration update message. The first DU 105 receives the request.

[0124] At 316, based on the request received at 315, the first DU 105 transmits the on-demand SIB1 of the second cell 122 to the user device 100 (or broadcasts the on-demand SIB1 of the second cell 122 on the first cell 121) based on the configuration of the on-demand SIB1 procedure towards the second cell 122. The user device 100 receives the on-demand SI B1 of the second cell 122.

[0125] The transmission of the on-demand SIB1 may comprise, for example, broadcasting the on-demand SIB1 , or transmitting the on-demand SIB1 via unicast or groupcast to the user device 100 that requested the on-demand SIB1 via the wake-up signal (i.e., the transmission may be UE-specific or UE-group specific or a broadcast).

[0126] At 317, the user device 100 synchronizes with the second cell 122 and reads and stores the on-demand SIB1 of the second cell 122. The on-demand SIB1 comprises the minimum system information needed for initial access to the second cell 122.

[0127] At 318, the user device 100 accesses the second cell 122 based on the on-demand SIB1 of the second cell 122.

[0128] At 319, the second CU 108B determines to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration).

[0129] Alternatively, the second DU 105B may determine to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration). In this case, the second DU 105B may indicate its deactivation decision to the second CU 108B over the F1 interface.

[0130] At 320, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell 122, the second CU 108B transmits, to the second DU 105B, a request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105B receives the request.

[0131] At 321 , based on the request received at 320 (or based on its own determination to deactivate the on-demand SIB1 transmission mode for the second cell 122), the second DU 105B updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122 (e.g., the legacy SIB1 transmission mode is resumed).

[0132] At 322, the second DU 105B starts the SIB1 transmission for the second cell 122 based on updating the master information block to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell, and / or that the SIB1 transmission is activated for the second cell.

[0133] At 323, the second DU 105B transmits, to the second CU 108B, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The second CU 108B receives the response.

[0134] At 324, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell 122, the second CU 108B transmits, to the first CU 108, a request message indicating that the on-demand SIB1 transmission mode is to be deactivated for the second cell 122. For example, the request message (e.g., called OD- SIB1 deactivation request) may be transmitted over the Xn interface. The first CU 108 receives the request message.

[0135] At 325, based on receiving the request message indicating that the on-demand SIB1 transmission mode is to be deactivated for the second cell 122, the first CU 108 stops transmitting (or broadcasting) the configuration information associated with the wake-up signal, as well as the on-demand SIB1 of the second cell 122. In other words, the first CU 108 transmits, to the first DU 105, an indication to stop transmitting (or broadcasting) the WUS configuration information and the on-demand SIB1 of the second cell 122, and the first DU 105 then stops transmitting (or broadcasting) the WUS configuration information and the on-demand SIB1 of the second cell 122 on the first cell 121.

[0136] At 326, the first CU 108 transmits, to the second CU 108B, a response message indicating that the transmission (or broadcast) of the WUS configuration information and the on-demand SIB1 of the second cell 122 has been stopped. For example, the response message (e.g., called OD-SIB1 deactivation response) may be transmitted over the Xn interface. The second CU 108B receives the response message.

[0137] At 327, the user device 100 discards or erases the configuration information associated with the wake-up signal, based on detecting that the validity duration has expired, or based on detecting that the transmission (or broadcast) of the WUS configuration information and / or the on-demand SIB1 of the second cell 122 has been stoppedon the first cell 121. Alternatively, the user device 100 may keep the configuration information without using it after the validity duration has expired.

[0138] FIG. 4 illustrates a signal flow diagram according to an example embodiment (corresponding to option 2 of Table 1 above). This example embodiment relates to the scenario of FIG. 2B, where the cell A 121 and the NES cell 122 are non-co-located (i.e., controlled by different access nodes 104, 104B).

[0139] Herein the cell A 121 is referred to as a first cell. The first cell 121 is controlled by a first DU 105, which is controlled by a first CU 108. In other words, the first CU 108 controls the first cell 121 via the first DU 105. The first CU 108 and the first DU 105 may be comprised in a first access node 104 (e.g., a gNB).

[0140] Furthermore, herein the NES cell 122 is referred to as a second cell. The second cell 122 is controlled by a second DU 105B, which is controlled by a second CU 108B. In other words, the second CU 108B controls the second cell 122 via the second DU 105B. The second CU 108B and the second DU 105B may be comprised in a second access node 104B (e.g., a gNB) different from the first access node 104.

[0141] Although only one user device 100 is shown in FIG. 4, it should be noted that the number of user devices may also be different than one. In other words, there may be one or more user devices, and the signaling procedure illustrated in FIG. 4 may be extended and applied according to the actual number of user devices.

[0142] A difference between FIG. 4 and FIG. 3 is that, in FIG. 4, the first CU 108 controlling the first cell 121 forwards the received wake-up signal to the second CU 108B controlling the second cell 122. The second CU 108B then identifies the corresponding second DU 105B from the identifier (e.g., PCI) comprised in the wake-up signal, and triggers OD-SIB1 transmission at the second DU 105B.

[0143] Referring to FIG. 4, at 401, the first DU 105 transmits, to the first CU 108, configuration information associated with a wake-up signal for requesting an on-demand SIB1 of the second cell 122 on the first cell 121. In other words, the configuration information associated with the wake-up signal is intended to be used by a user device 100 to request the on-demand SIB1 of the second cell 122.

[0144] For example, the configuration information may be transmitted over the F1 interface in an F1 setup request message or a DU configuration update request message. In other words, the first DU 105 owns the WUS configuration (identified by an identifier such as PCI) and sends it to the first CU 108 via F1 signaling. The first CU 108 receives the configuration information from the first DU 105.

[0145] At 402, the first CU 108 stores the configuration information for example in an internal memory of the first CU 108.

[0146] At 403, the second CU 108B determines to activate an on-demand SIB1 transmission mode for the second cell 122 controlled by the second CU 108B. Prior to the determination of 403, the second cell 122 may be in a non- on-demand SIB1 operation mode (e.g., transmitting the periodic legacy SIB1 ).

[0147] Alternatively, the second DU 105B may determine to activate the on-demand SIB1 transmission mode for the second cell 122. In this case, the second DU 105B may indicate its activation decision to the second CU 108B over the F1 interface.

[0148] At 404, based on the determination of 403, the second CU 108B transmits, to the first CU 108, a request message indicating that the on-demand SIB1 transmission mode is to be activated for the second cell 122 controlledby the second CU 108B. For example, the request message (e.g., called OD-SIB1 activation request) may be transmitted over the Xn interface. The first CU 108 receives the request message.

[0149] The request message comprises at least duration information indicating a validity duration of the on-demand SIB1 transmission mode for the second cell 122. The validity duration refers to the time duration of how long the on- demand SIB1 transmission mode will remain active or is expected to remain active. In other words, the validity duration comprises a time duration during which the user device 100 is allowed use the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell 122, wherein this time duration relates to the duration during which the second cell uses the on-demand SIB1 mode.

[0150] The request message may further comprise an identifier such as a physical cell identity (PCI) associated with the second cell 122.

[0151] At 405, the first CU 108 transmits, to the user device 100, via the first DU 105, the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell 122 on the first cell 121. In other words, the first CU 108 may transmit the configuration information to the first DU 105, and the first DU 105 may transmit or forward the configuration information to the user device 100 on the first cell 121. For example, the first DU 105 may broadcast the configuration information in a system information block of the first cell 121 . The user device 100 receives and stores the configuration information.

[0152] The configuration information indicates one or more conditions related to the wake-up signal (e.g., for transmitting the wake-up signal).

[0153] The configuration information may further comprise the duration information indicating the validity duration of the on-demand SIB1 transmission mode for the second cell 122. Alternatively, the first CU 108 may transmit the duration information separately to the user device 100 (via the first DU 105), and the user device 100 may receive the duration information from the first CU 108 in the separate transmission.

[0154] At 406, the first CU 108 transmits, to the second CU 108B, a response message indicating that the configuration information associated with the wake-up signal has been transmitted to the user device 100. For example, the response message (e.g., called OD-SIB1 activation response) may be transmitted over the Xn interface. The second CU 108B receives the response message.

[0155] At 407, the second CU 108B transmits, to the second DU 105B, a request for updating a master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that an SIB1 transmission (e.g., the periodic legacy SIB1 transmission) is deactivated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105B receives the request.

[0156] At 408, based on the request (or based on its own determination to activate the on-demand SIB1 transmission mode for the second cell 122), the second DU 105B updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122.

[0157] For example, the second DU 105B may update the ssb-SubcarrierOffset information element and the pdcch- ConfigSIBI information element in the MIB, as described above with reference to FIG. 3.

[0158] At 409, the second DU 105B stops the SIB1 transmission (broadcast) for the second cell 122 based on updating the master information block, and the second cell 122 enters the on-demand SIB1 transmission mode.

[0159] At 410, the second DU 105B transmits, to the second CU 108B, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The second CU 108B receives the response.

[0160] At 411, the user device 100 detects that the one or more conditions for transmitting the wake-up signal are fulfilled within the validity duration. For example, the one or more conditions for transmitting the wake-up signal may be related to at least one of: one or more radio conditions of the user device 100, or a presence of uplink data to be transmitted from the user device 100.

[0161] The one or more radio conditions refer to the quality of the wireless communication channel between the user device 100 and the network (e.g., the first DU 105 or the second DU 105B). Factors such as signal strength, interference, and noise may affect the one or more radio conditions.

[0162] The presence of uplink data to be transmitted from the user device 100 means that when the user device 100 has data to send in the uplink, the user device 100 may trigger the transmission of the wake-up signal.

[0163] At 412, the user device 100 transmits the wake-up signal to the first DU 105 based on the configuration information and within the validity duration. The first DU 105 monitors for the wake-up signal based on the configuration information, and receives the wake-up signal from the user device 100. The wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122, towards which the user device 100 is requesting the on-demand SIB1 transmission.

[0164] The purpose of the wake-up signal is to trigger the transmission of the on-demand SIB1 transmission of the second cell 122, which is in the on-demand SIB1 transmission mode (i.e., a type of energy-saving state).

[0165] By including the identifier associated with the second cell 122 in the wake-up signal, the user device 100 can inform the network about the cell from which it expects the OD-SIB1 . This is beneficial, because the identifier of the cell where the WUS is received may be different from the cell that broadcasts the OD-SIB1.

[0166] At 413, the first DU 105 transmits or forwards, to the first CU 108, the wake-up signal transmitted from the user device 100, wherein the wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122. For example, the first DU 105 may transmit the wake-up signal to the first CU 108 over the F1 interface. The first CU 108 receives the wake-up signal from the first DU 105.

[0167] At 414, the first CU 108 identifies the second access node 104B and / or the second CU 108B based on the identifier comprised in the wake-up signal.

[0168] At 415, based on the identification of 414, the first CU 108 transmits or forwards the wake-up signal to the second CU 108B (e.g., over the Xn interface), wherein the wake-up signal comprises or indicates the identifier associated with the second cell 122. The second CU 108B receives the wake-up signal from the first CU 108.

[0169] At 416, the second CU 108B identifies the second DU 105B based on the identifier comprised in the wake-up signal.

[0170] At 417, based on the identification of 416, the second CU 108B transmits, to the second DU 105B, a request for transmitting the on-demand SIB1 of the second cell 122 to the user device 100 (orfor broadcasting the on-demand SIB1 of the second cell 122 on the second cell 122). For example, the second CU 108B may transmit the request over the F1 interface in a gNB CU configuration update message. The second DU 105B receives the request. The configuration and the content of the on-demand SIB1 of the second cell 122 may be known or stored at the second DU 105B or included in the request.

[0171] At 418, based on the request received at 417, the second DU 105B transmits the on-demand SIB1 of the second cell 122 to the user device 100 (or broadcasts the on-demand SIB1 of the second cell 122 on the second cell 122) based on the configuration of the on-demand SIB1 of the second cell 122. The user device 100 receives the on- demand SI B1 of the second cell 122.

[0172] The transmission of the on-demand SIB1 may comprise, for example, broadcasting the on-demand SIB1 , or transmitting the on-demand SIB1 via unicast or groupcast to the user device 100 that requested the on-demand SIB1 via the wake-up signal (i.e., the transmission may be UE-specific or UE-group specific or a broadcast).

[0173] The user device 100 synchronizes with the second cell 122 and reads and stores the on-demand SIB1 of the second cell 122. The on-demand SIB1 comprises the minimum system information needed for initial access to the second cell 122.

[0174] At 419, the user device 100 accesses the second cell 122 based on the on-demand SIBlof the second cell 122.

[0175] At 420, the second CU 108B determines to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration).

[0176] Alternatively, the second DU 105B may determine to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration). In this case, the second DU 105B may indicate its deactivation decision to the second CU 108B over the F1 interface.

[0177] At 421, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell 122, the second CU 108B transmits, to the second DU 105B, a request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105B receives the request.

[0178] At 422, based on the request received at 421 (or based on its own determination to deactivate the on-demand SIB1 transmission mode for the second cell 122), the second DU 105B updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122 (i.e., the legacy SIB1 transmission mode is resumed).

[0179] At 423, the second DU stops transmitting (or broadcasting) the on-demand SIB1 of the second cell 122, and starts the SIB1 transmission for the second cell 122, based on updating the master information block to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell, and / or that the SIB1 transmission is activated for the second cell.

[0180] At 424, the second DU 105B transmits, to the second CU 108B, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The second CU 108B receives the response.

[0181] At 425, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell 122, the second CU 108B transmits, to the first CU 108, a request message indicating that the on-demand SIB1 transmission mode is to be deactivated for the second cell 122. For example, the request message (e.g., called OD- SIB1 deactivation request) may be transmitted over the Xn interface. The first CU 108 receives the request message.

[0182] At 426, based on receiving the request message indicating that the on-demand SIB1 transmission mode is to be deactivated for the second cell 122, the first CU 108 stops transmitting or broadcasting the configuration information associated with the wake-up signal. In other words, the first CU 108 transmits, to the first DU 105, an indication to stop transmitting or broadcasting the WUS configuration information, and the first DU 105 then stops transmitting or broadcasting the WUS configuration information on the first cell 121.

[0183] At 427, the first CU 108 transmits, to the second CU 108B, a response message indicating that the transmission (or broadcast) of the WUS configuration information has been stopped. For example, the response message (e.g., called OD-SIB1 deactivation response) may be transmitted over the Xn interface. The second CU 108B receives the response message.

[0184] The user device 100 may discard or erase the configuration information associated with the wake-up signal, based on detecting that the validity duration has expired, or based on detecting that the transmission (or broadcast) of the WUS configuration information and / or the on-demand SIB1 of the second cell 122 has been stopped. Alternatively, the user device 100 may keep the configuration information without using it after the validity duration has expired.

[0185] FIG. 5 illustrates a signal flow diagram according to an example embodiment (corresponding to option 3 of Table 1 above). This example embodiment relates to the scenario of FIG. 2B, where the cell A 121 and the NES cell 122 are non-co-located (i.e., controlled by different access nodes 104, 104B).

[0186] Herein the cell A 121 is referred to as a first cell. The first cell 121 is controlled by a first DU 105, which is controlled by a first CU 108. In other words, the first CU 108 controls the first cell 121 via the first DU 105. The first CU 108 and the first DU 105 may be comprised in a first access node 104 (e.g., a gNB).

[0187] Furthermore, herein the NES cell 122 is referred to as a second cell. The second cell 122 is controlled by a second DU 105B, which is controlled by a second CU 108B. In other words, the second CU 108B controls the second cell 122 via the second DU 105B. The second CU 108B and the second DU 105B may be comprised in a second access node 104B (e.g., a gNB) different from the first access node 104.

[0188] Although only one user device 100 is shown in FIG. 5, it should be noted that the number of user devices may also be different than one. In other words, there may be one or more user devices, and the signaling procedure illustrated in FIG. 5 may be extended and applied according to the actual number of user devices.

[0189] A difference between FIG. 5 and FIG. 4 is that, in FIG. 5, the second DU 105B controlling the second cell 122 owns the WUS configuration and sends it to the second CU 105B (e.g., via F1 signaling). The second CU 105B then sends the WUS configuration of the second cell 122 (e.g., via Xn signaling) to the first CU 105 controlling the first cell 121. In this case, the user device 100 transmits the wake-up signal to the second DU 105B (instead of to the first DU105 as shown in FIG. 3 and FIG. 4).

[0190] Referring to FIG. 5, at 501, the second DU 105B transmits, to the second CU 108B, configuration information associated with a wake-up signal for requesting an on-demand SIB1 of the second cell 122 on the second cell 122. In other words, the configuration information associated with the wake-up signal is intended to be used by a user device 100 to request the on-demand SIB1 of the second cell 122.

[0191] For example, the configuration information may be transmitted over the F1 interface in an F1 setup request message or a DU configuration update request message. In other words, the second DU 105B owns the WUS configuration (identified by an identifier such as PCI) and sends it to the second DU 108B via F1 signaling. The second CU 108B receives the configuration information associated with the wake-up signal from the second DU 105B.

[0192] At 502, the second CU 108B transmits, to the first CU 108, the configuration information associated with the wake-up signal. For example, the second CU 108B may transmit the configuration information over the Xn interface in an Xn setup request message. The first CU 108 receives the configuration information associated with the wakeup signal from the second CU 108B.

[0193] At 503, the first CU 108 stores the configuration information for example in an internal memory of the first CU 108.

[0194] At 504, the second CU 108B determines to activate an on-demand SIB1 transmission mode for the second cell 122 controlled by the second CU 108B. Prior to the determination of 504, the second cell 122 may be in a non- on-demand SIB1 operation mode (e.g., transmitting the periodic legacy SIB1 ).

[0195] Alternatively, the second DU 105B may determine to activate the on-demand SIB1 transmission mode for the second cell 122. In this case, the second DU 105B may indicate its activation decision to the second CU 108B over the F1 interface.

[0196] At 505, based on the determination of 504, the second CU 108B transmits, to the first CU 108, a request message indicating that the on-demand SIB1 transmission mode is to be activated for the second cell 122 controlled by the second CU 108B. For example, the request message (e.g., called OD-SIB1 activation request) may be transmitted over the Xn interface. The first CU 108 receives the request message.

[0197] The request message comprises at least duration information indicating a validity duration of the on-demand SIB1 transmission mode for the second cell 122. The validity duration refers to the time duration of how long the on- demand SIB1 transmission mode will remain active or is expected to remain active. In other words, the validity duration comprises a time duration during which the user device 100 is allowed use the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell 122, wherein this time duration relates to the duration during which the second cell uses the on-demand SIB1 mode.

[0198] The request message may further comprise an identifier such as a physical cell identity (PCI) associated with the second cell 122.

[0199] At 506, the first CU 108 transmits, to the user device 100, via the first DU 105, the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell 122 on the second cell 122. In other words, the first CU 108 may transmit the configuration information to the first DU 105, and the first DU 105 may transmit or forward the configuration information to the user device 100 on the first cell 121. For example, thefirst DU 105 may broadcast the configuration information in a system information block of the first cell 121. The user device 100 receives and stores the configuration information.

[0200] The configuration information indicates one or more conditions related to the wake-up signal (e.g., for transmitting the wake-up signal).

[0201] The configuration information may further comprise the duration information indicating the validity duration of the on-demand SIB1 transmission mode for the second cell 122. Alternatively, the first CU 108 may transmit the duration information separately to the user device 100 (via the first DU 105), and the user device 100 may receive the duration information from the first CU 108 in the separate transmission.

[0202] At 507, the first CU 108 transmits, to the second CU 108B, a response message indicating that the configuration information associated with the wake-up signal has been transmitted to the user device 100. For example, the response message (e.g., called OD-SIB1 activation response) may be transmitted over the Xn interface. The second CU 108B receives the response message.

[0203] At 508, the second CU 108B transmits, to the second DU 105B, a request for updating a master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that an SIB1 transmission (e.g., the periodic legacy SIB1 transmission) is deactivated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105B receives the request.

[0204] At 509, based on the request (or based on its own determination to activate the on-demand SIB1 transmission mode for the second cell 122), the second DU 105B updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122.

[0205] For example, the second DU 105B may update the ssb-SubcarrierOffset information element and the pdcch- ConfigSI B 1 information element in the MIB, as described above with reference to FIG. 3.

[0206] At 510, the second DU 105B stops the SIB1 transmission (broadcast) for the second cell 122 based on updating the master information block, and the second cell 122 enters the on-demand SIB1 transmission mode.

[0207] At 511, the second DU 105B transmits, to the second CU 108B, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The second CU 108B receives the response.

[0208] At 512, the user device 100 detects that the one or more conditions for transmitting the wake-up signal are fulfilled within the validity duration. For example, the one or more conditions for transmitting the wake-up signal may be related to at least one of: one or more radio conditions of the user device 100, or a presence of uplink data to be transmitted from the user device 100.

[0209] The one or more radio conditions refer to the quality of the wireless communication channel between the user device 100 and the network (e.g., the first DU 105 or the second DU 105B). Factors such as signal strength, interference, and noise may affect the one or more radio conditions.

[0210] The presence of uplink data to be transmitted from the user device 100 means that when the user device 100 has data to send in the uplink, the user device 100 may trigger the transmission of the wake-up signal.

[0211] At 513, the user device 100 transmits the wake-up signal to the second DU 105B based on the configuration information and within the validity duration. The second DU 105B monitors for the wake-up signal based on the configuration information, and receives the wake-up signal from the user device 100. The wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122, towards which the user device 100 is requesting the on-demand SIB1 transmission.

[0212] The purpose of the wake-up signal is to trigger the transmission of the on-demand SIB1 transmission of the second cell 122, which is in the on-demand SIB1 transmission mode (i.e., a type of energy-saving state).

[0213] At 514, the second DU 105B transmits or forwards, to the second CU 108B, the wake-up signal transmitted from the user device 100, wherein the wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122. For example, the second DU 105B may transmit the wake-up signal to the second CU 108B over the F1 interface. The second CU 108B receives the wake-up signal from the second DU 105B.

[0214] At 515, based on receiving the wake-up signal, the second CU 108B transmits, to the second DU 105B, a request for transmitting the on-demand SIB1 of the second cell 122 to the user device 100 (or for broadcasting the on-demand SIB1 of the second cell 122 on the second cell 122). For example, the second CU 108B may transmit the request over the F1 interface in a gNB CU configuration update message. The second DU 105B receives the request. The configuration and the content of the on-demand SIB1 of the second cell 122 may be known or stored at the second DU 105B or included in the request.

[0215] At 516, based on the request received at 515, the second DU 105B transmits the on-demand SIB1 of the second cell 122 to the user device 100 (or broadcasts the on-demand SIB1 of the second cell 122 on the second cell 122) based on the configuration of the on-demand SIB1 of the second cell 122. The user device 100 receives the on- demand SI B1 of the second cell 122.

[0216] The transmission of the on-demand SIB1 may comprise, for example, broadcasting the on-demand SIB1 , or transmitting the on-demand SIB1 via unicast or groupcast to the user device 100 that requested the on-demand SIB1 via the wake-up signal (i.e., the transmission may be UE-specific or UE-group specific or a broadcast).

[0217] The user device 100 synchronizes with the second cell 122 and reads and stores the on-demand SIB1 of the second cell 122. The on-demand SIB1 comprises the minimum system information needed for initial access to the second cell 122.

[0218] At 517, the user device 100 accesses the second cell 122 based on the on-demand SIB1 of the second cell 122.

[0219] At 518, the second CU 108B determines to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration).

[0220] Alternatively, the second DU 105B may determine to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration). In this case, the second DU 105B may indicate its activation decision to the second CU 108B over the F1 interface.

[0221] At 519, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell 122, the second CU 108B transmits, to the second DU 105B, a request for updating the master information block of thesecond cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105B receives the request.

[0222] At 520, based on the request received at 519 (or based on its own determination to deactivate the on-demand SIB1 transmission mode for the second cell 122), the second DU 105B updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122 (i.e., the legacy SIB1 transmission mode is resumed).

[0223] At 521, the second DU 105B stops transmitting (or broadcasting) the on-demand SIB1 of the second cell 122, and starts the SIB1 transmission for the second cell 122, based on updating the master information block to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell, and / or that the SIB1 transmission is activated for the second cell.

[0224] At 522, the second DU 105B transmits, to the second CU 108B, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The second CU 108B receives the response.

[0225] At 523, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell 122, the second CU 108B transmits, to the first CU 108, a request message indicating that the on-demand SIB1 transmission mode is to be deactivated for the second cell 122. For example, the request message (e.g., called OD- SIB1 deactivation request) may be transmitted over the Xn interface. The first CU 108 receives the request message.

[0226] At 524, based on receiving the request message indicating that the on-demand SIB1 transmission mode is to be deactivated for the second cell 122, the first CU 108 stops transmitting or broadcasting the configuration information associated with the wake-up signal. In other words, the first CU 108 transmits, to the first DU 105, an indication to stop transmitting or broadcasting the WUS configuration information, and the first DU 105 then stops transmitting or broadcasting the WUS configuration information for the second cell 122 on the first cell 121.

[0227] At 525, the first CU 108 transmits, to the second CU 108B, a response message indicating that the transmission (or broadcast) of the WUS configuration information has been stopped. For example, the response message (e.g., called OD-SIB1 deactivation response) may be transmitted over the Xn interface. The second CU 108B receives the response message.

[0228] The user device 100 may discard or erase the configuration information associated with the wake-up signal based on detecting that the validity duration has expired, or based on detecting that the transmission (or broadcast) of the WUS configuration information and / or the on-demand SIB1 of the second cell 122 has been stopped. Alternatively, the user device 100 may keep the configuration information without using it after the validity duration has expired.

[0229] FIG. 6 illustrates a signal flow diagram according to an example embodiment (corresponding to option 4 of Table 1 above). In this example embodiment, only the NES cell 122 is involved (i.e., the cell A 121 is not needed), which means that the NES cell 122 is responsible for the provisioning of the WUS configuration, the monitoring for the WUS, and the transmission of the OD-SIB1 when requested.

[0230] Herein the NES cell 122 is referred to as a second cell. The second cell 122 is controlled by a second DU 105B, which is controlled by a second CU 108B. In other words, the second CU 108B controls the second cell 122 via the second DU 105B. The second CU 108B and the second DU 105B may be comprised in an access node 104B (e.g., a gNB). It should be noted that the second DU 105B may also control one or more other cells (which may also be NES cells).

[0231] Although only one user device 100 is shown in FIG. 6, it should be noted that the number of user devices may also be different than one. In other words, there may be one or more user devices, and the signaling procedure illustrated in FIG. 6 may be extended and applied according to the actual number of user devices.

[0232] Referring to FIG. 6, at 601, the second DU 105B transmits, to the second CU 108B, configuration information associated with a wake-up signal for requesting an on-demand SIB1 of the second cell 122 on the second cell 122. In other words, the configuration information associated with the wake-up signal is intended to be used by a user device 100 to request the on-demand SIB1 of the second cell 122.

[0233] For example, the configuration information may be transmitted over the F1 interface in an F1 setup request message or a DU configuration update request message. In other words, the second DU 105B owns the WUS configuration (identified by an identifier such as PCI) and sends it to the second DU 108B via F1 signaling. The second CU 108B receives the configuration information associated with the wake-up signal from the second DU 105B.

[0234] At 602, the second CU 108B stores the configuration information for example in an internal memory of the second CU 108B.

[0235] At 603, the second CU 108B determines to activate an on-demand SIB1 transmission mode for the second cell 122 controlled by the second CU 108B. Prior to the determination of 603, the second cell 122 may be in a non- on-demand SIB1 operation mode (e.g., transmitting the periodic legacy SIB1).

[0236] Alternatively, the second DU 105B may determine to activate the on-demand SIB1 transmission mode for the second cell 122. In this case, the second DU 105B may indicate its activation decision to the second CU 108B over the F1 interface.

[0237] At 604, the second CU 108B transmits, to the user device 100, via the second DU 105B, the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell 122 on the second cell 122. In other words, the second CU 108B may transmit the configuration information to the second DU 105B, and the second DU 105B may transmit or forward the configuration information to the user device 100 on the second cell 122. For example, the second DU 105B may broadcast the configuration information in a system information block of the second cell 122. The user device 100 receives the configuration information.

[0238] For example, the configuration information may be transmitted in a radio resource control (RRC) container, when the user device 100 is in a connected (RRC_CONNECTED) state with the second cell 122.

[0239] At 605, the user device 100 stores the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell 122 on the second cell 122.

[0240] The configuration information indicates one or more conditions related to the wake-up signal (e.g., for transmitting the wake-up signal).

[0241] The configuration information may further comprise duration information indicating the validity duration of the on-demand SIB1 transmission mode for the second cell 122. Alternatively, the second CU 108B may transmit the duration information separately to the user device 100 (via the second DU 105B), and the user device 100 may receive the duration information from the second CU 108B in the separate transmission.

[0242] At 606, the second CU 108B transmits, to the second DU 105B, a request for updating a master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that an SIB1 transmission (e.g., the periodic legacy SIB1 transmission) is deactivated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105B receives the request.

[0243] At 607, based on the request (or based on its own determination to activate the on-demand SIB1 transmission mode for the second cell 122), the second DU 105B updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122.

[0244] For example, the second DU 105B may update the ssb-SubcarrierOffset information element and the pdcch- ConfigSI B 1 information element in the MIB, as described above with reference to FIG. 3.

[0245] At 608, the second DU 105B stops the SIB1 transmission (broadcast) for the second cell 122 based on updating the master information block, and the second cell 122 enters the on-demand SIB1 transmission mode.

[0246] At 609, the second DU 105B transmits, to the second CU 108B, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The second CU 108B receives the response.

[0247] At 610, the user device 100 detects that the one or more conditions for transmitting the wake-up signal are fulfilled within the validity duration. For example, the one or more conditions for transmitting the wake-up signal may be related to at least one of: one or more radio conditions of the user device 100, or a presence of uplink data to be transmitted from the user device 100.

[0248] The one or more radio conditions refer to the quality of the wireless communication channel between the user device 100 and the network (e.g., the second DU 105B). Factors such as signal strength, interference, and noise may affect the one or more radio conditions.

[0249] The presence of uplink data to be transmitted from the user device 100 means that when the user device 100 has data to send in the uplink, the user device 100 may trigger the transmission of the wake-up signal.

[0250] At 611, the user device 100 transmits the wake-up signal to the second DU 105B based on the configuration information and within the validity duration. The second DU 105B monitors for the wake-up signal based on the configuration information, and receives the wake-up signal from the user device 100. The wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122, towards which the user device 100 is requesting the on-demand SIB1 transmission.

[0251] The purpose of the wake-up signal is to trigger the transmission of the on-demand SIB1 transmission of the second cell 122, which is in the on-demand SIB1 transmission mode (i.e., a type of energy-saving state).

[0252] At 612, the second DU 105B transmits or forwards, to the second CU 108B, the wake-up signal transmitted from the user device 100, wherein the wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122. For example, the second DU 105B may transmit the wake-up signal to the second CU 108B over the F1 interface. The second CU 108B receives the wake-up signal from the second DU 105B.

[0253] At 613, the second CU 108B identifies, based on the identifier comprised in the wake-up signal, at least one of: the second DU 105B, the configuration for the on-demand SIB1 procedure towards the second cell 122, or the content of the on-demand SIB1 of the second cell 122.

[0254] At 614, based on the identification of 613, the second CU 108B transmits, to the second DU 105B, a request for transmitting the on-demand SIB1 of the second cell 122 to the user device 100 (orfor broadcasting the on-demand SIB1 of the second cell 122 on the second cell 122). For example, the second CU 108B may transmit the request over the F1 interface in a gNB CU configuration update message. The second DU 105B receives the request. The configuration and the content of the on-demand SIB1 of the second cell 122 may be known or stored at the second DU 105B or included in the request.

[0255] At 615, based on the request received at 614, the second DU 105B transmits the on-demand SIB1 of the second cell 122 to the user device 100 (or broadcasts the on-demand SIB1 of the second cell 122 on the second cell 122) based on the configuration of the on-demand SIB1 procedure towards the second cell 122. The user device 100 receives the on-demand SI B1 of the second cell 122.

[0256] The transmission of the on-demand SIB1 may comprise, for example, broadcasting the on-demand SIB1 , or transmitting the on-demand SIB1 via unicast or groupcast to the user device 100 that requested the on-demand SIB1 via the wake-up signal (i.e., the transmission may be UE-specific or UE-group specific or a broadcast).

[0257] At 616, the user device 100 synchronizes with the second cell 122 and reads and stores the on-demand SIB1 of the second cell 122. The on-demand SIB1 comprises the minimum system information needed for initial access to the second cell 122.

[0258] At 617, the user device 100 accesses the second cell 122 based on the on-demand SIB1 of the second cell 122.

[0259] At 618, the second CU 108B determines to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration).

[0260] Alternatively, the second DU 105B may determine to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration). In this case, the second DU 105B may indicate its activation decision to the second CU 108B over the F1 interface.

[0261] At 619, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell 122, the second CU 108B transmits, to the second DU 105B, a request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105B receives the request.

[0262] At 620, based on the request received at 619 (or based on its own determination to deactivate the on-demand SIB1 transmission mode for the second cell 122), the second DU 105B updates the master information block of thesecond cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122 (i.e., the legacy SIB1 transmission mode is resumed).

[0263] At 621, the second DU 105B stops transmitting (or broadcasting) the configuration information associated with the wake-up signal, stops transmitting (or broadcasting) the on-demand SIB1 of the second cell 122, and starts the SIB1 transmission for the second cell 122, based on updating the master information block to indicate that the on- demand SIB1 transmission mode is deactivated for the second cell, and / or that the SIB1 transmission is activated for the second cell.

[0264] At 622, the second DU 105B transmits, to the second CU 108B, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The second CU 108B receives the response.

[0265] At 623, the user device 100 may discard or erase the configuration information associated with the wake-up signal based on detecting that the validity duration has expired, or based on detecting that the transmission (or broadcast) of the WUS configuration information and / or the on-demand SIB1 of the second cell 122 has been stopped. Alternatively, the user device 100 may keep the configuration information without using it after the validity duration has expired.

[0266] FIG. 7 illustrates a signal flow diagram according to an example embodiment (corresponding to option 1 in Table 1 above). This example embodiment relates to the scenario of FIG. 2A, where the cell A 121 and the NES cell 122 are co-located (i.e., controlled by the same access node 104). In this example embodiment, the cell A 121 and the NES cell 122 are controlled by different DUs 105, 105A of the same access node 104.

[0267] Herein the cell A 121 is referred to as a first cell. The first cell 121 is controlled by a first DU 105, which is controlled by a CU 108. In other words, the CU 108 controls the first cell 121 via the first DU 105.

[0268] Furthermore, herein the NES cell 122 is referred to as a second cell. The second cell 122 is controlled by a second DU 105A, which is controlled by the same CU 108. In other words, the CU 108 controls the second cell 122 via the second DU 105A. The CU 108, the first DU 105, and the second DU 105A may be comprised in the same access node 104B (e.g., a gNB).

[0269] Although only one user device 100 is shown in FIG. 7, it should be noted that the number of user devices may also be different than one. In other words, there may be one or more user devices, and the signaling procedure illustrated in FIG. 7 may be extended and applied according to the actual number of user devices.

[0270] In this example embodiment, the DUs 105, 105A provide their cell-level configuration of WUS and OD-SIB1 to the CU 108 over the F1 interface. When the CU 108 decides to enable the OD-SIB1 transmission mode in the second cell 122, it initiates the broadcast of the WUS configuration in the first cell 121 (controlled by the first DU 105) and requests the second DU 105Ato indicate the stopping of SIB-1 transmission in the MIB. Once the MIB is updated, the legacy SIB-1 broadcast is stopped. Subsequently, the WUS is handled through the first cell 121 resulting in OD- SIB1 broadcast in the first cell 121.

[0271] Referring to FIG. 7, at 701 , the first DU 105 transmits, to the CU 108, configuration information associated with a wake-up signal for requesting an on-demand SIB1 on the first cell 121 (i.e., WUS configuration information ofthe first cell 121). For example, the WUS configuration information provided by the first DU 105 may be used by a user device 100 to request the on-demand SIB1 of the second cell 122 on the first cell 121. The configuration information may be transmitted over the F1 interface, for example, in an F1 setup request message or a DU configuration update request message. The CU 108 receives the configuration information from the first DU 105.

[0272] The configuration information of the first cell 121 indicates one or more conditions related to the wake-up signal (e.g., for transmitting the wake-up signal on the first cell 121).

[0273] The configuration information associated with the wake-up signal of the first cell 121 may further comprise duration information indicating a validity duration of an on-demand SIB1 transmission mode for the first cell 121. Alternatively, the first DU 105 may transmit the duration information separately to the CU 108.

[0274] The configuration information associated with the wake-up signal of the first cell 121 may further comprise an identifier such as a physical cell identity (PCI) associated with the first cell 121.

[0275] The first DU 105 may also transmit, to the CU 108, a configuration for an on-demand SIB1 procedure towards the first cell 121. The configuration for the on-demand SIB1 procedure may be included in the same message as the configuration information associated with the wake-up signal. Alternatively, the configuration for the on-demand SIB1 procedure may be transmitted in a separate message (e.g., over the F1 interface).

[0276] For example, the configuration for the on-demand SIB1 procedure towards the first cell 121 may comprise a radio resource configuration for transmitting the on-demand SIB1 of the first cell 121.

[0277] The first DU 105 may also transmit, to the CU 108, a content of the on-demand SIB1 of the first cell 121, for example together with the configuration for the on-demand SIB1 procedure towards the first cell 121. The content and the configuration for the on-demand SIB1 of the first cell 121 may be identifiable by the identifier of the first cell 121.

[0278] At 702, the second DU 105A transmits, to the CU 108, configuration information associated with a wake-up signal for requesting an on-demand SIB1 on the second cell 122 (i.e., WUS configuration information of the second cell 122). For example, the WUS configuration information provided by the second DU 105A may be used by the user device 100 to request the on-demand SIB1 of the second cell 122 on the second cell 122. The configuration information may be transmitted over the F1 interface, for example, in an F1 setup request message or a DU configuration update request message. The CU 108 receives the configuration information from the second DU 105A.

[0279] The configuration information of the second cell 122 indicates one or more conditions related to the wake-up signal (e.g., for transmitting the wake-up signal on the second cell 122).

[0280] The configuration information associated with the wake-up signal of the second cell 122 may further comprise duration information indicating a validity duration of an on-demand SIB1 transmission mode for the second cell 122. Alternatively, the second DU 105A may transmit the duration information separately to the CU 108.

[0281] The configuration information associated with the wake-up signal of the second cell 122 may further comprise an identifier such as a physical cell identity (PCI) associated with the second cell 122.

[0282] The second DU 105A may also transmit, to the CU 108, a configuration for an on-demand SIB1 procedure towards the second cell 122. The configuration for the on-demand SIB1 procedure may be included in the same message as the configuration information associated with the wake-up signal. Alternatively, the configuration for the on-demand SIB1 procedure may be transmitted in a separate message (e.g., over the F1 interface).

[0283] For example, the configuration for the on-demand SIB1 procedure towards the second cell 122 may comprise a radio resource configuration for transmitting the on-demand SIB1 of the second cell 122.

[0284] The second DU 105A may also transmit, to the CU 108, a content of the on-demand SIB1 of the second cell 122, for example together with the configuration for the on-demand SIB1 procedure towards the second cell 122. The content and the configuration for the on-demand SIB1 of the second cell 122 may be identifiable by the identifier of the second cell 122.

[0285] At 703, the CU 108 stores the information received at 701 and 702 (e.g., in an internal memory of the CU 108).

[0286] At 704, the CU 108 determines to activate the on-demand SIB1 transmission mode for the second cell 122 controlled by the second DU 105A. Prior to the determination of 704, the second cell 122 may be in a non-on-demand SIB1 operation mode (e.g., transmitting the periodic legacy SIB1 transmission).

[0287] Alternatively, the second DU 105A may determine to activate the on-demand SIB1 transmission mode for the second cell 122. In this case, the second DU 105A may indicate its activation decision to the CU 108 over the F1 interface.

[0288] At 705, the CU 108 transmits, to a user device 100, via the first DU 105, the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell 122 on the first cell 121 (i.e., the WUS configuration received from the first DU 105 at 701). In other words, the CU 108 may transmit the configuration information to the first DU 105, and the first DU 105 may transmit or forward the configuration information to the user device 100 on the first cell 121. For example, the first DU 105 may broadcast the configuration information in a system information block of the first cell 121. The user device 100 receives and stores the configuration information.

[0289] The CU 108 may also transmit, to the user device 100, via the first DU 105, the duration information indicating the validity duration of the on-demand SIB1 transmission mode of the second cell 122. The duration information may be transmitted together with the configuration information, or separately from the configuration information.

[0290] At 706, the CU 108 transmits, to the second DU 105A, a request for updating a master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that an SIB1 transmission (e.g., the periodic legacy SIB1 transmission) is deactivated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105A receives the request.

[0291] At 707, based on the request (or based on its own determination to activate the on-demand SIB1 transmission mode for the second cell 122), the second DU 105A updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122.

[0292] For example, the second DU 105A may update the ssb-SubcarrierOffset information element and the pdcch- ConfigSIBI information element in the MIB, as described above with reference to FIG. 3.

[0293] At 708, the second DU 105A stops the SIB1 transmission (broadcast) for the second cell 122 based on updating the master information block, and the second cell 122 enters the on-demand SIB1 transmission mode.

[0294] At 709, the second DU 105A transmits, to the CU 108, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The CU 108 receives the response.

[0295] At 710, the user device 100 detects that the one or more conditions (indicated in the configuration information received at 705) for transmitting the wake-up signal are fulfilled within the validity duration. For example, the one or more conditions for transmitting the wake-up signal may be related to at least one of: one or more radio conditions of the user device 100, or a presence of uplink data to be transmitted from the user device 100.

[0296] The one or more radio conditions refer to the quality of the wireless communication channel between the user device 100 and the network (e.g., the first DU 105 or the second DU 105A). Factors such as signal strength, interference, and noise may affect the one or more radio conditions.

[0297] The presence of uplink data to be transmitted from the user device 100 means that when the user device 100 has data to send in the uplink, the user device 100 may trigger the transmission of the wake-up signal.

[0298] At 711, the user device 100 transmits the wake-up signal to the first DU 105 based on the configuration information and within the validity duration. The first DU 105 monitors for the wake-up signal based on the configuration information, and receives the wake-up signal from the user device 100. The wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122, towards which the user device 100 is requesting the on-demand SIB1 transmission.

[0299] The purpose of the wake-up signal is to trigger the transmission of the on-demand SIB1 transmission of the second cell 122, which is in the on-demand SIB1 transmission mode (i.e., a type of energy-saving state).

[0300] At 712, the first DU 105 transmits or forwards, to the CU 108, the wake-up signal transmitted from the user device 100, wherein the wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122. For example, the first DU 105 may transmit the wake-up signal to the CU 108 over the F1 interface. The CU 108 receives the wake-up signal from the first DU 105.

[0301] At 713, the CU 108 identifies the configuration and / or the content for the on-demand SIB1 of the second cell 122 based on the identifier comprised in the wake-up signal. In other words, the CU 108 identifies the OD-SIB1 information from the received PCI and then triggers the transmission of the on-demand SIB1 of the second cell 122.

[0302] At 714, the CU 108 transmits, to the first DU 105, a request for transmitting the on-demand SIB1 of the second cell 122 to the user device 100 (or for broadcasting the on-demand SIB1 of the second cell 122 on the first cell 121), wherein the request comprises the configuration and the content for the on-demand SIB1 (provided by the second DU 105A at 702), which were identified based on the wake-up signal. For example, the CU 108 may transmit the request over the F1 interface in a gNB CU configuration update message. The first DU 105 receives the request.

[0303] At 715, based on the request received at 714, the first DU 105 transmits the on-demand SIB1 of the second cell 122 to the user device 100 (or broadcasts the on-demand SIB1 of the second cell 122 on the first cell 121) based on the configuration of the on-demand SIB1 procedure towards the second cell 122. The user device 100 receives the on-demand SI B1 of the second cell 122.

[0304] The transmission of the on-demand SIB1 may comprise, for example, broadcasting the on-demand SIB1 , or transmitting the on-demand SIB1 via unicast or groupcast to the user device 100 that requested the on-demand SIB1 via the wake-up signal (i.e., the transmission may be UE-specific or UE-group specific or a broadcast).

[0305] At 716, the user device 100 synchronizes with the second cell 122 and reads and stores the on-demand SIB1 of the second cell 122. The on-demand SIB1 comprises the minimum system information needed for initial access to the second cell 122.

[0306] At 717, the user device 100 accesses the second cell 122 based on the on-demand SIB1 of the second cell 122.

[0307] At 718, the CU 108 determines to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration).

[0308] Alternatively, the second DU 105A may determine to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration). In this case, the second DU 105A may indicate its deactivation decision to the CU 108 over the F1 interface.

[0309] At 719, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell 122, the CU 108 transmits, to the second DU 105A, a request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105A receives the request.

[0310] At 720, based on the request received at 719 (or based on its own determination to deactivate the on-demand SIB1 transmission mode for the second cell 122), the second DU 105A updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122 (i.e., the legacy SIB1 transmission mode is resumed).

[0311] At 721, the second DU 105A starts the SIB1 transmission for the second cell 122 based on updating the master information block to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell, and / or that the SIB1 transmission is activated for the second cell.

[0312] At 722, the second DU 105A transmits, to the CU 108, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The CU 108 receives the response.

[0313] At 723, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell 122, the CU 108 stops transmitting (or broadcasting) the configuration information associated with the wake-up signal, as well as the on-demand SIB1 of the second cell 122. In other words, the CU 108 transmits, to the first DU 105, an indication to stop transmitting (or broadcasting) the WUS configuration information and the on-demand SIB1 of the second cell 122, and the first DU 105 then stops transmitting (or broadcasting) the WUS configuration information and the on-demand SIB1 of the second cell 122 on the first cell 121.

[0314] At 724, the user device 100 discards or erases the configuration information associated with the wake-up signal based on detecting that the validity duration has expired, or based on detecting that the transmission (orbroadcast) of the WUS configuration information and / or the on-demand SIB1 of the second cell 122 has been stopped on the first cell 121. Alternatively, the user device 100 may keep the configuration information without using it after the validity duration has expired.

[0315] FIG. 8 illustrates a signal flow diagram according to an example embodiment (corresponding to option 2 in Table 1 above). This example embodiment relates to the scenario of FIG. 2A, where the cell A 121 and the NES cell 122 are co-located (i.e., controlled by the same access node 104). In this example embodiment, the cell A 121 and the NES cell 122 are controlled by different DUs 105, 105A of the same access node 104.

[0316] Herein the cell A 121 is referred to as a first cell. The first cell 121 is controlled by a first DU 105, which is controlled by a CU 108. In other words, the CU 108 controls the first cell 121 via the first DU 105.

[0317] Furthermore, herein the NES cell 122 is referred to as a second cell. The second cell 122 is controlled by a second DU 105A, which is controlled by the same CU 108. In other words, the CU 108 controls the second cell 122 via the second DU 105A. The CU 108, the first DU 105, and the second DU 105A may be comprised in the same access node 104B (e.g., a gNB).

[0318] Although only one user device 100 is shown in FIG. 8, it should be noted that the number of user devices may also be different than one. In other words, there may be one or more user devices, and the signaling procedure illustrated in FIG. 8 may be extended and applied according to the actual number of user devices.

[0319] A difference between FIG. 8 and FIG. 7 is that, in FIG. 8, the OD-SIB1 is broadcasted in the second cell 122 (by the second DU 105A). In FIG. 7, the OD-SIB1 is broadcasted in the first cell 121 (by the first DU 105).

[0320] Referring to FIG. 8, at 801 , the first DU 105 transmits, to the CU 108, configuration information associated with a wake-up signal for requesting an on-demand SIB1 on the first cell 121 (i.e., WUS configuration information of the first cell 121). For example, the WUS configuration information provided by the first DU 105 may be used by a user device 100 to request the on-demand SIB1 of the second cell 122 on the first cell 121. The configuration information may be transmitted over the F1 interface, for example, in an F1 setup request message or a DU configuration update request message. The CU 108 receives the configuration information from the first DU 105.

[0321] The configuration information of the first cell 121 indicates one or more conditions related to the wake-up signal (e.g., for transmitting the wake-up signal on the first cell 121).

[0322] The configuration information associated with the wake-up signal of the first cell 121 may further comprise duration information indicating a validity duration of an on-demand SIB1 transmission mode for the first cell 121. Alternatively, the first DU 105 may transmit the duration information separately to the CU 108.

[0323] The configuration Information associated with the wake-up signal of the first cell 121 may further comprise an identifier such as a physical cell identity (PCI) associated with the first cell 121.

[0324] The first DU 105 may also transmit, to the CU 108, a configuration for an on-demand SIB1 procedure towards the first cell 121. The configuration for the on-demand SIB1 procedure may be included in the same message as the configuration information associated with the wake-up signal. Alternatively, the configuration for the on-demand SIB1 procedure may be transmitted in a separate message (e.g., over the F1 interface).

[0325] For example, the configuration for the on-demand SIB1 procedure towards the first cell 121 may comprise a radio resource configuration for transmitting the on-demand SIB1 of the first cell 121.

[0326] The first DU 105 may also transmit, to the CU 108, a content of the on-demand SIB1 of the first cell 121 , for example together with the configuration for the on-demand SIB1 procedure towards the first cell 121. The content and the configuration for the on-demand SIB1 of the first cell 121 may be identifiable by the identifier of the first cell121.

[0327] At 802, the second DU 105A transmits, to the CU 108, configuration information associated with a wake-up signal for requesting an on-demand SIB1 on the second cell 122 (i.e., WUS configuration information of the second cell 122). For example, the WUS configuration information provided by the second DU 105A may be used by the user device 100 to request the on-demand SIB1 of the second cell 122 on the second cell 122. The configuration information may be transmitted over the F1 interface, for example, in an F1 setup request message or a DU configuration update request message. The CU 108 receives the configuration information from the second DU 105A.

[0328] The configuration information of the second cell 122 indicates one or more conditions related to the wake-up signal (e.g., for transmitting the wake-up signal on the second cell 122).

[0329] The configuration information associated with the wake-up signal of the second cell 122 may further comprise duration information indicating a validity duration of an on-demand SIB1 transmission mode for the second cell 122. Alternatively, the second DU 105A may transmit the duration information separately to the CU 108.

[0330] The configuration information associated with the wake-up signal of the second cell 122 may further comprise an identifier such as a physical cell identity (PCI) associated with the second cell 122.

[0331] The second DU 105A may also transmit, to the CU 108, a configuration for an on-demand SIB1 procedure towards the second cell 122. The configuration for the on-demand SIB1 procedure may be included in the same message as the configuration information associated with the wake-up signal. Alternatively, the configuration for the on-demand SIB1 may be transmitted in a separate message (e.g., over the F1 interface).

[0332] For example, the configuration for the on-demand SIB1 procedure towards the second cell 122 may comprise a radio resource configuration for transmitting the on-demand SIB1 of the second cell 122.

[0333] The second DU 105A may also transmit, to the CU 108, a content of the on-demand SIB1 of the second cell122, for example together with the configuration for the on-demand SIB1 procedure towards the second cell 122. The content and the configuration for the on-demand SIB1 of the second cell 122 may be identifiable by the identifier of the second cell 122.

[0334] At 803, the CU 108 stores the information received at 801 and 802 (e.g., in an internal memory of the CU 108).

[0335] At 804, the CU 108 determines to activate the on-demand SIB1 transmission mode for the second cell 122 controlled by the second DU 105A. Prior to the determination of 804, the second cell 122 may be in a non-on-demand SIB1 operation mode (e.g., transmitting the periodic legacy SIB1 transmission).

[0336] Alternatively, the second DU 105A may determine to activate the on-demand SIB1 transmission mode for the second cell 122. In this case, the second DU 105A may indicate its activation decision to the CU 108 over the F1 interface.

[0337] At 805, the CU 108 transmits, to a user device 100, via the first DU 105, the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell 122 on the first cell 121 (i.e., the WUS configuration received from the first DU 105 at 801). In other words, the CU 108 may transmit theconfiguration information to the first DU 105, and the first DU 105 may transmit or forward the configuration information to the user device 100 on the first cell 121. For example, the first DU 105 may broadcast the configuration information in a system information block of the first cell 121. The user device 100 receives and stores the configuration information.

[0338] The CU 108 may also transmit, to the user device 100, via the first DU 105, the duration information indicating the validity duration of the on-demand SIB1 transmission mode of the second cell 122. The duration information may be transmitted together with the configuration information, or separately from the configuration information.

[0339] At 806, the CU 108 transmits, to the second DU 105A, a request for updating a master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that an SIB1 transmission (e.g., the periodic legacy SIB1 transmission) is deactivated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105A receives the request.

[0340] At 807, based on the request (or based on its own determination to activate the on-demand SIB1 transmission mode for the second cell 122), the second DU 105A updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122.

[0341] For example, the second DU 105A may update the ssb-SubcarrierOffset information element and the pdcch- ConfigSI B 1 information element in the MIB, as described above with reference to FIG. 3.

[0342] At 808, the second DU 105A stops the SIB1 transmission (broadcast) for the second cell 122 based on updating the master information block, and the second cell 122 enters the on-demand SIB1 transmission mode.

[0343] At 809, the second DU 105A transmits, to the CU 108, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The CU 108 receives the response.

[0344] At 810, the user device 100 detects that the one or more conditions (indicated in the configuration information received at 805) for transmitting the wake-up signal are fulfilled within the validity duration. For example, the one or more conditions for transmitting the wake-up signal may be related to at least one of: one or more radio conditions of the user device 100, or a presence of uplink data to be transmitted from the user device 100.

[0345] The one or more radio conditions refer to the quality of the wireless communication channel between the user device 100 and the network (e.g., the first DU 105 or the second DU 105A). Factors such as signal strength, interference, and noise may affect the one or more radio conditions.

[0346] The presence of uplink data to be transmitted from the user device 100 means that when the user device 100 has data to send in the uplink, the user device 100 may trigger the transmission of the wake-up signal.

[0347] At 811, the user device 100 transmits the wake-up signal to the first DU 105 based on the configuration information and within the validity duration. The first DU 105 monitors for the wake-up signal based on the configuration information, and receives the wake-up signal from the user device 100. The wake-up signal comprisesor indicates the identifier (e.g., PCI) associated with the second cell 122, towards which the user device 100 is requesting the on-demand SIB1 transmission.

[0348] The purpose of the wake-up signal is to trigger the transmission of the on-demand SIB1 transmission of the second cell 122, which is in the on-demand SIB1 transmission mode (i.e., a type of energy-saving state).

[0349] At 812, the first DU 105 transmits or forwards, to the CU 108, the wake-up signal transmitted from the user device 100, wherein the wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122. For example, the first DU 105 may transmit the wake-up signal to the CU 108 over the F1 interface. The CU 108 receives the wake-up signal from the first DU 105.

[0350] At 813, the CU 108 identifies the configuration and / or the content for the on-demand SIB1 of the second cell 122 based on the identifier comprised in the wake-up signal. In other words, the CU 108 identifies the OD-SIB1 information from the received PCI and then triggers the transmission of the on-demand SIB1 of the second cell 122.

[0351] At 814, the CU 108 transmits, to the second DU 105A, a request for transmitting the on-demand SIB1 of the second cell 122 to the user device 100 (or for broadcasting the on-demand SIB1 of the second cell 122 on the second cell 122). The request may comprise or indicate the configuration and the content for the on-demand SIB1 (provided by the second DU 105A at 802), which were identified based on the wake-up signal. For example, the CU 108 may transmit the request over the F1 interface in a gNB CU configuration update message. The second DU 105A receives the request.

[0352] At 815, based on the request received at 814, the second DU 105A transmits the on-demand SIB1 of the second cell 122 to the user device 100 (or broadcasts the on-demand SIB1 of the second cell 122 on the second cell 122) based on the configuration of the on-demand SIB1 procedure towards the second cell 122. The user device 100 receives the on-demand SI B1 of the second cell 122.

[0353] The transmission of the on-demand SIB1 may comprise, for example, broadcasting the on-demand SIB1 , or transmitting the on-demand SIB1 via unicast or groupcast to the user device 100 that requested the on-demand SIB1 via the wake-up signal (i.e., the transmission may be UE-specific or UE-group specific or a broadcast).

[0354] At 816, the user device 100 synchronizes with the second cell 122 and reads and stores the on-demand SIB1 of the second cell 122. The on-demand SIB1 comprises the minimum system information needed for initial access to the second cell 122.

[0355] At 817, the user device 100 accesses the second cell 122 based on the on-demand SIB1 of the second cell 122.

[0356] At 818, the CU 108 determines to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration).

[0357] Alternatively, the second DU 105A may determine to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration). In this case, the second DU 105A may indicate its deactivation decision to the CU 108 over the F1 interface.

[0358] At 819, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell 122, the CU 108 transmits, to the second DU 105A, a request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that theSIB1 transmission is activated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105A receives the request.

[0359] At 820, based on the request received at 819 (or based on its own determination to deactivate the on-demand SIB1 transmission mode for the second cell 122), the second DU 105A updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122 (i.e., the legacy SIB1 transmission mode is resumed).

[0360] At 821, the second DU 105A stops transmitting (or broadcasting) the on-demand SIB1 of the second cell 122 and starts the SIB1 transmission for the second cell 122, based on updating the master information block to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell, and / or that the SIB1 transmission is activated for the second cell.

[0361] At 822, the second DU 105A transmits, to the CU 108, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The CU 108 receives the response.

[0362] At 823, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell 122, the CU 108 stops transmitting (or broadcasting) the configuration information associated with the wake-up signal. In other words, the CU 108 transmits, to the first DU 105, an indication to stop transmitting (or broadcasting) the WUS configuration information, and the first DU 105 then stops transmitting (or broadcasting) the WUS configuration information on the first cell 121.

[0363] At 824, the user device 100 discards or erases the configuration information associated with the wake-up signal based on detecting that the validity duration has expired, based on detecting that the transmission (or broadcast) of the WUS configuration information and / or the on-demand SIB1 of the second cell 122 has been stopped. Alternatively, the user device 100 may keep the configuration information without using it after the validity duration has expired.

[0364] FIG. 9 illustrates a signal flow diagram according to an example embodiment (corresponding to option 3 in Table 1 above). This example embodiment relates to the scenario of FIG. 2A, where the cell A 121 and the NES cell 122 are co-located (i.e., controlled by the same access node 104). In this example embodiment, the cell A 121 and the NES cell 122 are controlled by different DUs 105, 105A of the same access node 104.

[0365] Herein the cell A 121 is referred to as a first cell. The first cell 121 is controlled by a first DU 105, which is controlled by a CU 108. In other words, the CU 108 controls the first cell 121 via the first DU 105.

[0366] Furthermore, herein the NES cell 122 is referred to as a second cell. The second cell 122 is controlled by a second DU 105A, which is controlled by the same CU 108. In other words, the CU 108 controls the second cell 122 via the second DU 105A. The CU 108, the first DU 105, and the second DU 105A may be comprised in the same access node 104B (e.g., a gNB).

[0367] Although only one user device 100 is shown in FIG. 9, it should be noted that the number of user devices may also be different than one. In other words, there may be one or more user devices, and the signaling procedure illustrated in FIG. 9 may be extended and applied according to the actual number of user devices.

[0368] A difference between FIG. 9 and FIG. 8 is that, in FIG. 9, the wake-up signal is handled through the second cell 122 (via the second DU 105A). In FIG. 8, the wake-up signal is handled through the first cell 121 (via the first DU 105).

[0369] Referring to FIG. 9, at 901, the first DU 105 transmits, to the CU 108, configuration information associated with a wake-up signal for requesting an on-demand SIB1 on the first cell 121 (i.e., WUS configuration information of the first cell 121). For example, the WUS configuration information provided by the first DU 105 may be used by a user device 100 to request the on-demand SIB1 of the second cell 122 on the first cell 121. The configuration information may be transmitted over the F1 interface, for example, in an F1 setup request message or a DU configuration update request message. The CU 108 receives the configuration information from the first DU 105.

[0370] The configuration information of the first cell 121 indicates one or more conditions related to the wake-up signal (e.g., for transmitting the wake-up signal on the first cell 121).

[0371] The configuration information associated with the wake-up signal of the first cell 121 may further comprise duration information indicating a validity duration of an on-demand SIB1 transmission mode for the first cell 121. Alternatively, the first DU 105 may transmit the duration information separately to the CU 108.

[0372] The configuration information associated with the wake-up signal of the first cell 121 may further comprise an identifier such as a physical cell identity (PCI) associated with the first cell 121.

[0373] The first DU 105 may also transmit, to the CU 108, a configuration for an on-demand SIB1 procedure towards the first cell 121. The configuration for the on-demand SIB1 procedure may be included in the same message as the configuration information associated with the wake-up signal. Alternatively, the configuration for the on-demand SIB1 procedure may be transmitted in a separate message (e.g., over the F1 interface).

[0374] For example, the configuration for the on-demand SIB1 procedure towards the first cell 121 may comprise a radio resource configuration for transmitting the on-demand SIB1 of the first cell 121.

[0375] The first DU 105 may also transmit, to the CU 108, a content of the on-demand SIB1 of the first cell 121 , for example together with the configuration for the on-demand SIB1 procedure towards the first cell 121. The content and the configuration for the on-demand SIB1 of the first cell 121 may be identifiable by the identifier of the first cell 121.

[0376] At 902, the second DU 105A transmits, to the CU 108, configuration information associated with a wake-up signal for requesting an on-demand SIB1 on the second cell 122 (i.e., WUS configuration information of the second cell 122). For example, the WUS configuration information provided by the second DU 105A may be used by the user device 100 to request the on-demand SIB1 of the second cell 122 on the second cell 122. The configuration information may be transmitted over the F1 interface, for example, in an F1 setup request message or a DU configuration update request message. The CU 108 receives the configuration information from the second DU 105A.

[0377] The configuration information of the second cell 122 indicates one or more conditions related to the wake-up signal (e.g., for transmitting the wake-up signal on the second cell 122).

[0378] The configuration information associated with the wake-up signal of the second cell 122 may further comprise duration information indicating a validity duration of an on-demand SIB1 transmission mode for the second cell 122. Alternatively, the second DU 105A may transmit the duration information separately to the CU 108.

[0379] The configuration information associated with the wake-up signal of the second cell 122 may further comprise an identifier such as a physical cell identity (PCI) associated with the second cell 122.

[0380] The second DU 105A may also transmit, to the CU 108, a configuration for an on-demand SIB1 procedure towards the second cell 122. The configuration for the on-demand SIB1 procedure may be included in the same message as the configuration information associated with the wake-up signal. Alternatively, the configuration for the on-demand SIB1 procedure may be transmitted in a separate message (e.g., over the F1 interface).

[0381] For example, the configuration for the on-demand SIB1 procedure towards the second cell 122 may comprise a radio resource configuration for transmitting the on-demand SIB1 of the second cell 122.

[0382] The second DU 105A may also transmit, to the CU 108, a content of the on-demand SIB1 of the second cell 122, for example together with the configuration for the on-demand SIB1 procedure towards the second cell 122. The content and the configuration for the on-demand SIB1 of the second cell 122 may be identifiable by the identifier of the second cell 122.

[0383] At 903, the CU 108 stores the information received at 901 and 902 (e.g., in an internal memory of the CU 108).

[0384] At 904, the CU 108 determines to activate the on-demand SIB1 transmission mode for the second cell 122 controlled by the second DU 105A. Prior to the determination of 904, the second cell 122 may be in a non-on-demand SIB1 operation mode (e.g., transmitting the periodic legacy SIB1 transmission).

[0385] Alternatively, the second DU 105A may determine to activate the on-demand SIB1 transmission mode for the second cell 122. In this case, the second DU 105A may indicate its activation decision to the CU 108 over the F1 interface.

[0386] At 905, the CU 108 transmits, to a user device 100, via the first DU 105, the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell 122 on the second cell 122 (i.e., the WUS configuration received from the second DU 105A at 902). In other words, the CU 108 may transmit the configuration information to the first DU 105, and the first DU 105 may transmit or forward the configuration information to the user device 100. For example, the first DU 105 may broadcast the configuration information in a system information block of the first cell 121. The user device 100 receives and stores the configuration information.

[0387] The CU 108 may also transmit, to the user device 100, via the first DU 105, the duration information indicating the validity duration of the on-demand SIB1 transmission mode of the second cell 122. The duration information may be transmitted together with the configuration information, or separately from the configuration information.

[0388] At 906, the CU 108 transmits, to the second DU 105A, a request for updating a master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that an SIB1 transmission (e.g., the periodic legacy SIB1 transmission) is deactivated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105A receives the request.

[0389] At 907, based on the request (or based on its own determination to activate the on-demand SIB1 transmission mode for the second cell 122), the second DU 105A updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122.

[0390] For example, the second DU 105A may update the ssb-SubcarrierOffset information element and the pdcch- ConfigSI B 1 information element in the MIB, as described above with reference to FIG. 3.

[0391] At 908, the second DU 105A stops the SIB1 transmission (broadcast) for the second cell 122 based on updating the master information block, and the second cell 122 enters the on-demand SIB1 transmission mode.

[0392] At 909, the second DU 105A transmits, to the CU 108, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The CU 108 receives the response.

[0393] At 910, the user device 100 detects that the one or more conditions (indicated in the configuration information received at 905) for transmitting the wake-up signal are fulfilled within the validity duration. For example, the one or more conditions for transmitting the wake-up signal may be related to at least one of: one or more radio conditions of the user device 100, or a presence of uplink data to be transmitted from the user device 100.

[0394] The one or more radio conditions refer to the quality of the wireless communication channel between the user device 100 and the network (e.g., the first DU 105 or the second DU 105A). Factors such as signal strength, interference, and noise may affect the one or more radio conditions.

[0395] The presence of uplink data to be transmitted from the user device 100 means that when the user device 100 has data to send in the uplink, the user device 100 may trigger the transmission of the wake-up signal.

[0396] At 911, the user device 100 transmits the wake-up signal to the second DU 105A based on the configuration information and within the validity duration. The second DU 105A monitors for the wake-up signal based on the configuration information, and receives the wake-up signal from the user device 100. The wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122, towards which the user device 100 is requesting the on-demand SIB1 transmission.

[0397] The purpose of the wake-up signal is to trigger the transmission of the on-demand SIB1 transmission of the second cell 122, which is in the on-demand SIB1 transmission mode (i.e., a type of energy-saving state).

[0398] At 912, the second DU 105A transmits or forwards, to the CU 108, the wake-up signal transmitted from the user device 100, wherein the wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122. For example, the second DU 105A may transmit the wake-up signal to the CU 108 over the F1 interface. The CU 108 receives the wake-up signal from the second DU 105A.

[0399] At 913, the CU 108 identifies the configuration and / or the content for the on-demand SIB1 of the second cell 122 based on the identifier comprised in the wake-up signal. In other words, the CU 108 identifies the OD-SIB1 information from the received PCI and then triggers the transmission of the on-demand SIB1 of the second cell 122.

[0400] At 914, the CU 108 transmits, to the second DU 105A, a request for transmitting the on-demand SIB1 of the second cell 122 to the user device 100 (or for broadcasting the on-demand SIB1 of the second cell 122 on the second cell 122). The request may comprise or indicate the configuration and the content for the on-demand SIB1 (provided by the second DU 105A at 802), which were identified based on the wake-up signal. For example, the CU 108 may transmit the request over the F1 interface in a gNB CU configuration update message. The second DU 105A receives the request.

[0401] At 915, based on the request received at 914, the second DU 105A transmits the on-demand SIB1 of the second cell 122 to the user device 100 (or broadcasts the on-demand SIB1 of the second cell 122 on the second cell 122) based on the configuration of the on-demand SIB1 procedure towards the second cell 122. The user device 100 receives the on-demand SI B1 of the second cell 122.

[0402] The transmission of the on-demand SIB1 may comprise, for example, broadcasting the on-demand SIB1 , or transmitting the on-demand SIB1 via unicast or groupcast to the user device 100 that requested the on-demand SIB1 via the wake-up signal (i.e., the transmission may be UE-specific or UE-group specific or a broadcast).

[0403] At 916, the user device 100 synchronizes with the second cell 122 and reads and stores the on-demand SIB1 of the second cell 122. The on-demand SIB1 comprises the minimum system information needed for initial access to the second cell 122.

[0404] At 917, the user device 100 accesses the second cell 122 based on the on-demand SIB1 of the second cell 122.

[0405] At 918, the CU 108 determines to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration).

[0406] Alternatively, the second DU 105A may determine to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration). In this case, the second DU 105A may indicate its deactivation decision to the CU 108 over the F1 interface.

[0407] At 919, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell 122, the CU 108 transmits, to the second DU 105A, a request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105A receives the request.

[0408] At 920, based on the request received at 919 (or based on its own determination to deactivate the on-demand SIB1 transmission mode for the second cell 122), the second DU 105A updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122 (i.e., the legacy SIB1 transmission mode is resumed).

[0409] At 921, the second DU 105A stops transmitting (or broadcasting) the on-demand SIB1 of the second cell 122 and starts the SIB1 transmission for the second cell 122, based on updating the master information block to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell, and / or that the SIB1 transmission is activated for the second cell.

[0410] At 922, the second DU 105A transmits, to the CU 108, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The CU 108 receives the response.

[0411] At 923, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell 122, the CU 108 stops transmitting (or broadcasting) the configuration information associated with the wake-up signal. In other words, the CU 108 transmits, to the first DU 105, an indication to stop transmitting (or broadcasting) the WUSconfiguration information, and the first DU 105 then stops transmitting (or broadcasting) the WUS configuration information on the first cell 121.

[0412] At 924, the user device 100 discards or erases the configuration information associated with the wake-up signal based on detecting that the validity duration has expired, or based on detecting that the transmission (or broadcast) of the WUS configuration information and / or the on-demand SIB1 of the second cell 122 has been stopped. Alternatively, the user device 100 may keep the configuration information without using it after the validity duration has expired.

[0413] FIG. 10 illustrates a signal flow diagram according to an example embodiment (corresponding to option 4 in Table 1 above). This example embodiment relates to the scenario of FIG. 2A, where the cell A 121 and the NES cell 122 are co-located (i.e., controlled by the same access node 104). In this example embodiment, the cell A 121 and the NES cell 122 are controlled by different DUs 105, 105A of the same access node 104.

[0414] Herein the cell A 121 is referred to as a first cell. The first cell 121 is controlled by a first DU 105, which is controlled by a CU 108. In other words, the CU 108 controls the first cell 121 via the first DU 105.

[0415] Furthermore, herein the NES cell 122 is referred to as a second cell. The second cell 122 is controlled by a second DU 105A, which is controlled by the same CU 108. In other words, the CU 108 controls the second cell 122 via the second DU 105A. The CU 108, the first DU 105, and the second DU 105A may be comprised in the same access node 104B (e.g., a gNB).

[0416] Although only one user device 100 is shown in FIG. 10, it should be noted that the number of user devices may also be different than one. In other words, there may be one or more user devices, and the signaling procedure illustrated in FIG. 10 may be extended and applied according to the actual number of user devices.

[0417] A difference between FIG. 10 and FIG. 9 is that, in FIG. 10, the second DU 105A broadcasts the WUS configuration to the user device 100. In FIG. 9, the first DU 105 broadcasts the WUS configuration to the user device 100. In other words, in FIG. 10, all the DU-side processing happens in the second DU 105A: broadcasting the WUS configuration to the user device 100, disabling the normal (legacy) SIB1 transmission, handling the WUS from the user device 100, and broadcasting the on-demand SIB1.

[0418] Referring to FIG. 10, at 1001, the first DU 105 transmits, to the CU 108, configuration information associated with a wake-up signal for requesting an on-demand SIB1 on the first cell 121 (i.e., WUS configuration information of the first cell 121). For example, the WUS configuration information provided by the first DU 105 may be used by a user device 100 to request the on-demand SIB1 of the second cell 122 on the first cell 121. The configuration information may be transmitted over the F1 interface, for example, in an F1 setup request message or a DU configuration update request message. The CU 108 receives the configuration information from the first DU 105.

[0419] The configuration information of the first cell 121 indicates one or more conditions related to the wake-up signal (e.g., for transmitting the wake-up signal on the first cell 121).

[0420] The configuration information associated with the wake-up signal of the first cell 121 may further comprise duration information indicating a validity duration of an on-demand SIB1 transmission mode for the first cell 121. Alternatively, the first DU 105 may transmit the duration information separately to the CU 108.

[0421] The configuration information associated with the wake-up signal of the first cell 121 may further comprise an identifier such as a physical cell identity (PCI) associated with the first cell 121.

[0422] The first DU 105 may also transmit, to the CU 108, a configuration for an on-demand SIB1 procedure towards the first cell 121. The configuration for the on-demand SIB1 procedure may be included in the same message as the configuration information associated with the wake-up signal. Alternatively, the configuration for the on-demand SIB1 procedure may be transmitted in a separate message (e.g., over the F1 interface).

[0423] For example, the configuration for the on-demand SIB1 procedure towards the first cell 121 may comprise a radio resource configuration for transmitting the on-demand SIB1 of the first cell 121.

[0424] The first DU 105 may also transmit, to the CU 108, a content of the on-demand SIB1 of the first cell 121 , for example together with the configuration for the on-demand SIB1 procedure towards the first cell 121. The content and the configuration for the on-demand SIB1 of the first cell 121 may be identifiable by the identifier of the first cell121.

[0425] At 1002, the second DU 105A transmits, to the CU 108, configuration information associated with a wake-up signal for requesting an on-demand SIB1 on the second cell 122 (i.e., WUS configuration information of the second cell 122). For example, the WUS configuration information provided by the second DU 105A may be used by the user device 100 to request the on-demand SIB1 of the second cell 122 on the second cell 122. The configuration information may be transmitted over the F1 interface, for example, in an F1 setup request message or a DU configuration update request message. The CU 108 receives the configuration information from the second DU 105A.

[0426] The configuration information of the second cell 122 indicates one or more conditions related to the wake-up signal (e.g., for transmitting the wake-up signal on the second cell 122).

[0427] The configuration information associated with the wake-up signal of the second cell 122 may further comprise duration information indicating a validity duration of an on-demand SIB1 transmission mode for the second cell 122. Alternatively, the second DU 105A may transmit the duration information separately to the CU 108.

[0428] The configuration information associated with the wake-up signal of the second cell 122 may further comprise an identifier such as a physical cell identity (PCI) associated with the second cell 122.

[0429] The second DU 105A may also transmit, to the CU 108, a configuration for an on-demand SIB1 procedure towards the second cell 122. The configuration for the on-demand SIB1 procedure may be included in the same message as the configuration information associated with the wake-up signal. Alternatively, the configuration for the on-demand SIB1 procedure may be transmitted in a separate message (e.g., over the F1 interface).

[0430] For example, the configuration for the on-demand SIB1 procedure towards the second cell 122 may comprise a radio resource configuration for transmitting the on-demand SIB1 of the second cell 122.

[0431] The second DU 105A may also transmit, to the CU 108, a content of the on-demand SIB1 of the second cell122, for example together with the configuration for the on-demand SIB1 procedure towards the second cell 122. The content and the configuration for the on-demand SIB1 of the second cell 122 may be identifiable by the identifier of the second cell 122.

[0432] At 1003, the CU 108 stores the information received at 1001 and 1002 (e.g., in an internal memory of the CU 108).

[0433] At 1004, the CU 108 determines to activate the on-demand SIB1 transmission mode for the second cell 122 controlled by the second DU 105A. Prior to the determination of 1004, the second cell 122 may be in a non-on- demand SIB1 operation mode (e.g., transmitting the periodic legacy SIB1 transmission).

[0434] Alternatively, the second DU 105A may determine to activate the on-demand SIB1 transmission mode for the second cell 122. In this case, the second DU 105A may indicate its activation decision to the CU 108 over the F1 interface.

[0435] At 1005, the CU 108 transmits, to a user device 100, via the second DU 105A, the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell 122 on the second cell 122 (i.e., the WUS configuration received from the second DU 105A at 1002). In other words, the CU 108 may transmit the configuration information to the second DU 105A, and the second DU 105A may transmit or forward the configuration information to the user device 100. For example, the second DU 105A may broadcast the configuration information in a system information block of the second cell 122. The user device 100 receives and stores the configuration information.

[0436] The CU 108 may also transmit, to the user device 100, via the second DU 105A, the duration information indicating the validity duration of the on-demand SIB1 transmission mode of the second cell 122. The duration information may be transmitted together with the configuration information, or separately from the configuration information.

[0437] At 1006, the CU 108 transmits, to the second DU 105A, a request for updating a master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that an SIB1 transmission (e.g., the periodic legacy SIB1 transmission) is deactivated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105A receives the request.

[0438] At 1007, based on the request (or based on its own determination to activate the on-demand SIB1 transmission mode for the second cell 122), the second DU 105A updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122.

[0439] For example, the second DU 105A may update the ssb-SubcarrierOffset information element and the pdcch- ConfigSI B 1 information element in the MIB, as described above with reference to FIG. 3.

[0440] At 1008, the second DU 105A stops the SIB1 transmission (broadcast) for the second cell 122 based on updating the master information block, and the second cell 122 enters the on-demand SIB1 transmission mode.

[0441] At 1009, the second DU 105A transmits, to the CU 108, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The CU 108 receives the response.

[0442] At 1010, the user device 100 detects that the one or more conditions (indicated in the configuration information received at 1005) for transmitting the wake-up signal are fulfilled within the validity duration. For example, the one or more conditions for transmitting the wake-up signal may be related to at least one of: one or more radio conditions of the user device 100, or a presence of uplink data to be transmitted from the user device 100.

[0443] The one or more radio conditions refer to the quality of the wireless communication channel between the user device 100 and the network (e.g., the first DU 105 or the second DU 105A). Factors such as signal strength, interference, and noise may affect the one or more radio conditions.

[0444] The presence of uplink data to be transmitted from the user device 100 means that when the user device 100 has data to send in the uplink, the user device 100 may trigger the transmission of the wake-up signal.

[0445] At 1011, the user device 100 transmits the wake-up signal to the second DU 105A based on the configuration information and within the validity duration. The second DU 105A monitors for the wake-up signal based on the configuration information, and receives the wake-up signal from the user device 100. The wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122, towards which the user device 100 is requesting the on-demand SIB1 transmission.

[0446] The purpose of the wake-up signal is to trigger the transmission of the on-demand SIB1 transmission of the second cell 122, which is in the on-demand SIB1 transmission mode (i.e., a type of energy-saving state).

[0447] At 1012, the second DU 105A transmits or forwards, to the CU 108, the wake-up signal transmitted from the user device 100, wherein the wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122. For example, the second DU 105A may transmit the wake-up signal to the CU 108 over the F1 interface. The CU 108 receives the wake-up signal from the second DU 105A.

[0448] At 1013, the CU 108 identifies the configuration and / or the content for the on-demand SIB1 of the second cell 122 based on the identifier comprised in the wake-up signal. In other words, the CU 108 identifies the OD-SIB1 information from the received PCI and then triggers the transmission of the on-demand SIB1 of the second cell 122.

[0449] At 1014, the CU 108 transmits, to the second DU 105A, a request for transmitting the on-demand SIB1 of the second cell 122 to the user device 100 (or for broadcasting the on-demand SIB1 of the second cell 122 on the second cell 122). The request may comprise or indicate the configuration and the content for the on-demand SIB1 (provided by the second DU 105A at 802), which were identified based on the wake-up signal. For example, the CU 108 may transmit the request over the F1 interface in a gNB CU configuration update message. The second DU 105A receives the request.

[0450] At 1015, based on the request received at 1014, the second DU 105A transmits the on-demand SIB1 of the second cell 122 to the user device 100 (or broadcasts the on-demand SIB1 of the second cell 122 on the second cell 122) based on the configuration of the on-demand SIB1 procedure towards the second cell 122. The user device 100 receives the on-demand SI B1 of the second cell 122.

[0451] The transmission of the on-demand SIB1 may comprise, for example, broadcasting the on-demand SIB1 , or transmitting the on-demand SIB1 via unicast or groupcast to the user device 100 that requested the on-demand SIB1 via the wake-up signal (i.e., the transmission may be UE-specific or UE-group specific or a broadcast).

[0452] At 1016, the user device 100 synchronizes with the second cell 122 and reads and stores the on-demand SIB1 of the second cell 122. The on-demand SIB1 comprises the minimum system information needed for initial access to the second cell 122.

[0453] At 1017, the user device 100 accesses the second cell 122 based on the on-demand SIB1 of the second cell 122.

[0454] At 1018, the CU 108 determines to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration).

[0455] Alternatively, the second DU 105A may determine to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration). In this case, the second DU 105A may indicate its deactivation decision to the CU 108 over the F1 interface.

[0456] At 1019, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell 122, the CU 108 transmits, to the second DU 105A, a request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The second DU 105A receives the request.

[0457] At 1020, based on the request received at 1019 (or based on its own determination to deactivate the on- demand SIB1 transmission mode for the second cell 122), the second DU 105A updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122 (i.e., the legacy SIB1 transmission mode is resumed).

[0458] At 1021, the second DU 105B stops transmitting (or broadcasting) the configuration information associated with the wake-up signal, stops transmitting (or broadcasting) the on-demand SIB1 of the second cell 122, and starts the SIB1 transmission for the second cell 122, based on updating the master information block to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell, and / or that the SIB1 transmission is activated for the second cell.

[0459] At 1022, the second DU 105A transmits, to the CU 108, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The CU 108 receives the response.

[0460] At 1023, the user device 100 discards or erases the configuration information associated with the wake-up signal based on detecting that the validity duration has expired, or based on detecting that the transmission (or broadcast) of the WUS configuration information and / or the on-demand SIB1 of the second cell 122 has been stopped. Alternatively, the user device 100 may keep the configuration information without using it after the validity duration has expired.

[0461] FIG. 11 illustrates a signal flow diagram according to an example embodiment (corresponding to option 1 in Table 1 above). This example embodiment relates to the scenario of FIG. 2A, where the cell A 121 and the NES cell 122 are co-located (i.e., controlled by the same access node 104). In this example embodiment, the cell A 121 and the NES cell 122 are controlled by the same DU 105A of the access node 104. In this case, all the F1 signaling happens with the same DU 105A, and there is no Xn signaling involved. It should be noted that the solution options 2, 3 and 4 of Table 1 may also be realized with a single DU with similar F1 signaling changes as shown in FIG. 11.

[0462] Herein the cell A 121 is referred to as a first cell, and the NES cell 122 is referred to as a second cell. The DU 105A is controlled by a CU 108. In other words, the CU 108 controls the first cell 121 and the second cell 122 via the DU 105A. The CU 108 and the DU 105A may be comprised in the same access node 104 (e.g., a gNB).

[0463] Although only one user device 100 is shown in FIG. 11, it should be noted that the number of user devices may also be different than one. In other words, there may be one or more user devices, and the signaling procedure illustrated in FIG. 11 may be extended and applied according to the actual number of user devices.

[0464] Referring to FIG. 11, at 1101, the DU 105A transmits, to the CU 108, configuration information associated with a wake-up signal for requesting an on-demand SIB1 on the first cell 121 (i.e., WUS configuration information of the first cell 121), and configuration information associated with a wake-up signal for requesting an on-demand SIB1 on the second cell 122 (i.e., WUS configuration information of the second cell 122). For example, the WUS configuration information of the second cell 122 may be used by a user device 100 to request the on-demand SIB1 of the second cell 122 on the second cell 122. The configuration information may be transmitted over the F1 interface, for example, in an F1 setup request message or a DU configuration update request message. The CU 108 receives the configuration information from the DU 105A.

[0465] The configuration information associated with the wake-up signal indicates one or more conditions related to the wake-up signal (e.g., for transmitting the wake-up signal).

[0466] The WUS configuration information of the first cell 121 may further comprise duration information indicating a validity duration of an on-demand SIB1 transmission mode for the first cell 121. Alternatively, the DU 105A may transmit the duration information separately to the CU 108.

[0467] The WUS configuration information of the second cell 122 may further comprise duration information indicating a validity duration of an on-demand SIB1 transmission mode for the second cell 122. Alternatively, the DU 105A may transmit the duration information separately to the CU 108.

[0468] The WUS configuration information of the first cell 121 may further comprise an identifier such as a physical cell identity (PCI) associated with the first cell 121.

[0469] The WUS configuration information of the second cell 122 may further comprise an identifier such as a physical cell identity (PCI) associated with the second cell 122.

[0470] The DU 105A may also transmit, to the CU 108, a configuration for an on-demand SIB1 procedure towards the first cell 121, and a configuration for an on-demand SIB1 procedure towards the second cell 122. The configurations for the on-demand SIB1 procedures may be included in the same message as the configuration information associated with the wake-up signal. Alternatively, the configurations for the on-demand SIB1 procedures may be transmitted in a separate message (e.g., over the F1 interface).

[0471] For example, the configuration for the on-demand SIB1 procedure towards the first cell 122 may comprise a radio resource configuration for transmitting the on-demand SIB1 of the first cell 121.

[0472] For example, the configuration for the on-demand SIB1 procedure towards the second cell 122 may comprise a radio resource configuration for transmitting the on-demand SIB1 of the second cell 122.

[0473] The DU 105A may also transmit, to the CU 108, a content of the on-demand SIB1 of the first cell 121, and a content of the on-demand SIB1 of the second cell 122, for example together with the configuration for the on-demandSIB1 procedure of the respective cell. The content and the configuration for the on-demand SIB1 may be identifiable by the identifier of the respective cell.

[0474] At 1102, the CU 108 stores the information received at 1101 and 1102 (e.g., in an internal memory of the CU 108).

[0475] At 1103, the CU 108 determines to activate the on-demand SIB1 transmission mode for the second cell 122 controlled by the DU 105A. Prior to the determination of 1104, the second cell 122 may be in a non-on-demand SIB1 operation mode (e.g., transmitting the periodic legacy SIB1 transmission).

[0476] Alternatively, the DU 105A may determine to activate the on-demand SIB1 transmission mode for the second cell 122. In this case, the DU 105A may indicate its activation decision to the CU 108 over the F1 interface.

[0477] At 1104, the CU 108 transmits, to a user device 100, via the DU 105A, the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell 122 on the second cell 122 (i.e., the WUS configuration information of the second cell 122). In other words, the CU 108 may transmit the configuration information to the DU 105A, and the DU 105A may transmit or forward the configuration information to the user device 100 on the first cell 121. For example, the DU 105A may broadcast the configuration information in a system information block of the first cell 121. The user device 100 receives and stores the configuration information.

[0478] The CU 108 may also transmit, to the user device 100, via the DU 105A, the duration information indicating the validity duration of the on-demand SIB1 transmission mode of the second cell 122. The duration information may be transmitted together with the configuration information, or separately from the configuration information.

[0479] At 1105, the CU 108 transmits, to the DU 105A, a request for updating a master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that an SIB1 transmission (e.g., the periodic legacy SIB1 transmission) is deactivated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The DU 105A receives the request.

[0480] At 1106, based on the request (or based on its own determination to activate the on-demand SIB1 transmission mode for the second cell 122), the DU 105A updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122.

[0481] For example, the DU 105A may update the ssb-SubcarrierOffset information element and the pdcch- ConfigSI B 1 information element in the MIB, as described above with reference to FIG. 3.

[0482] At 1107, the DU 105A stops the SIB1 transmission (broadcast) for the second cell 122 based on updating the master information block, and the second cell 122 enters the on-demand SIB1 transmission mode.

[0483] At 1108, the DU 105A transmits, to the CU 108, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is activated for the second cell 122, and / or that the SIB1 transmission is deactivated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The CU 108 receives the response.

[0484] At 1109, the user device 100 detects that the one or more conditions (indicated in the configuration information received at 1104) for transmitting the wake-up signal are fulfilled within the validity duration. For example, the one ormore conditions for transmitting the wake-up signal may be related to at least one of: one or more radio conditions of the user device 100, or a presence of uplink data to be transmitted from the user device 100.

[0485] The one or more radio conditions refer to the quality of the wireless communication channel between the user device 100 and the network (e.g., the DU 105A). Factors such as signal strength, interference, and noise may affect the one or more radio conditions.

[0486] The presence of uplink data to be transmitted from the user device 100 means that when the user device 100 has data to send in the uplink, the user device 100 may trigger the transmission of the wake-up signal.

[0487] At 1110, the user device 100 transmits the wake-up signal to the DU 105A based on the configuration information and within the validity duration. The DU 105A monitors for the wake-up signal based on the configuration information, and receives the wake-up signal from the user device 100. The wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122, towards which the user device 100 is requesting the on- demand SIB1 transmission.

[0488] The purpose of the wake-up signal is to trigger the transmission of the on-demand SIB1 transmission of the second cell 122, which is in the on-demand SIB1 transmission mode (i.e., a type of energy-saving state).

[0489] At 1111, the DU 105A transmits or forwards, to the CU 108, the wake-up signal transmitted from the user device 100, wherein the wake-up signal comprises or indicates the identifier (e.g., PCI) associated with the second cell 122. For example, the DU 105A may transmit the wake-up signal to the CU 108 over the F1 interface. The CU 108 receives the wake-up signal from the DU 105A.

[0490] At 1112, the CU 108 identifies the configuration and / or the content for the on-demand SIB1 of the second cell 122 based on the identifier comprised in the wake-up signal. In other words, the CU 108 identifies the OD-SIB1 information from the received PCI and then triggers the transmission of the on-demand SIB1 of the second cell 122.

[0491] At 1113, the CU 108 transmits, to the DU 105A, a request for transmitting the on-demand SIB1 of the second cell 122 to the user device 100 (or for broadcasting the on-demand SIB1 of the second cell 122 on the first cell 121 or on the second cell 122), wherein the request comprises the configuration and the content for the on-demand SIB1 (provided by the DU 105A at 1101), which were identified based on the wake-up signal. For example, the CU 108 may transmit the request over the F1 interface in a gNB CU configuration update message. The DU 105A receives the request.

[0492] At 1114, based on the request received at 1113, the DU 105A transmits the on-demand SIB1 of the second cell 122 to the user device 100 (or broadcasts the on-demand SIB1 of the second cell 122 on the first cell 121 or on the second cell 122) based on the configuration of the on-demand SIB1 procedure towards the second cell 122. The user device 100 receives the on-demand SIB1 of the second cell 122.

[0493] The transmission of the on-demand SIB1 may comprise, for example, broadcasting the on-demand SIB1 , or transmitting the on-demand SIB1 via unicast or groupcast to the user device 100 that requested the on-demand SIB1 via the wake-up signal (i.e., the transmission may be UE-specific or UE-group specific or a broadcast).

[0494] At 1115, the user device 100 synchronizes with the second cell 122 and reads and stores the on-demand SIB1 of the second cell 122. The on-demand SIB1 comprises the minimum system information needed for initial access to the second cell 122.

[0495] At 1116, the user device 100 accesses the second cell 122 based on the on-demand SIB1 of the second cell 122.

[0496] At 1117, the CU 108 determines to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration).

[0497] Alternatively, the DU 105A may determine to deactivate the on-demand SIB1 transmission mode for the second cell 122 (e.g., at the end of the validity duration). In this case, the DU 105A may indicate its deactivation decision to the CU 108 over the F1 interface.

[0498] At 1118, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell 122, the CU 108 transmits, to the DU 105A, a request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the request may be transmitted over the F1 interface in a gNB CU configuration update message. The DU 105A receives the request.

[0499] At 1119, based on the request received at 1118 (or based on its own determination to deactivate the on- demand SIB1 transmission mode for the second cell 122), the DU 105A updates the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122 (i.e., the legacy SIB1 transmission mode is resumed).

[0500] At 1120, the DU 105A stops transmitting (or broadcasting) the configuration information associated with the wake-up signal, stops transmitting (or broadcasting) the on-demand SIB1 of the second cell 122, and starts the SIB1 transmission for the second cell 122, based on updating the master information block to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell, and / or that the SIB1 transmission is activated for the second cell.

[0501] At 1121, the DU 105A transmits, to the CU 108, a response indicating an acknowledgement to the request for updating the master information block of the second cell 122 to indicate that the on-demand SIB1 transmission mode is deactivated for the second cell 122, and / or that the SIB1 transmission is activated for the second cell 122. For example, the response may be transmitted over the F1 interface in a gNB CU configuration update acknowledgement message. The CU 108 receives the response.

[0502] At 1122, the user device 100 discards or erases the configuration information associated with the wake-up signal based on detecting that the validity duration has expired, or based on detecting that the transmission (or broadcast) of the WUS configuration information and / or the on-demand SIB1 of the second cell 122 has been stopped on the first cell 121. Alternatively, the user device 100 may keep the configuration information without using it after the validity duration has expired.

[0503] FIG. 12 illustrates a flow chart according to an example embodiment of a method for signaling to support on- demand SIB1. The method of FIG. 12 may be performed by the first central unit 108 of FIGS. 3 to 5 controlling the first cell 121.

[0504] Referring to FIG. 12, in block 1201, the first central unit receives, from a second central unit controlling a second cell, a request to broadcast configuration information associated with a wake-up signal for requesting an on- demand system information block type one (SIB1 ) of the second cell. In other words, the wake-up signal is intendedfor requesting the on-demand SIB1 of the second cell, and the first central unit receives the configuration information for transmitting the wake-up signal.

[0505] In block 1202, based on receiving the request, the first central unit broadcasts the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell.

[0506] The configuration information may indicate one or more conditions related to the wake-up signal.

[0507] The request may comprise duration information indicating a validity duration of the configuration information associated with the wake-up signal. The first central unit may broadcast the duration information.

[0508] The first central unit may transmit, to the second central unit, a response message indicating that the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell is being broadcasted on the first cell. The first central unit may determine to generate and / or transmit the response message based on broadcasting the configuration information on the first cell.

[0509] The first central unit may receive, from a first distributed unit controlling the first cell, the configuration information associated with the wake-up signal; and store the configuration information received from the first distributed unit (prior to broadcasting it).

[0510] Alternatively, the first central unit may receive, from the second central unit, the configuration information associated with the wake-up signal; and store the configuration information received from the second central unit (prior to broadcasting it).

[0511] The request received from the second central unit may comprise an identifier associated with the second cell, a configuration for an on-demand SIB1 procedure towards the second cell, and a content of the on-demand SIB1 of the second cell.

[0512] The first central unit may receive, from a first distributed unit controlling the first cell, the wake-up signal transmitted from a user device, wherein the wake-up signal indicates the identifier associated with the second cell; identify the configuration for the on-demand SIB1 procedure based on the identifier indicated in the wake-up signal; and transmit, to the first distributed unit, a request for transmitting the on-demand SIB1 of the second cell, wherein the request transmitted to the first distributed unit comprises the configuration for the on-demand SIB1 procedure, and the content of the on-demand SIB1 of the second cell. The first central unit may determine to generate and / or transmit the request to the first distributed unit based on the identification.

[0513] Alternatively, the first central unit may receive, from a first distributed unit controlling the first cell, the wake-up signal transmitted from a user device, wherein the wake-up signal indicates an identifier associated with the second cell; identify the second central unit based on the identifier indicated in the wake-up signal; and transmit the wakeup signal to the second central unit. The first central unit may determine to transmit the wake-up signal to the second central unit based on the identification.

[0514] The first central unit may receive, from the second central unit, a request to stop broadcasting the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell; stop broadcasting the configuration information associated with the wake-up signal, based on receiving the request to stop the broadcasting; and transmit, to the second central unit, a response message indicating that the broadcasting of the configuration information associated with the wake-up signal is stopped. The first central unit may determine to generate and / or transmit the response message based on stopping the broadcasting.

[0515] FIG. 13 illustrates a flow chart according to an example embodiment of a method for signaling to support on- demand SIB1. The method of FIG. 13 may be performed by the second central unit 108B of FIGS. 3 to 5 controlling the second cell 122.

[0516] Referring to FIG. 13, in block 1301, the second central unit transmits, to a first central unit controlling a first cell, a request to broadcast configuration information associated with a wake-up signal for requesting an on-demand system information block type one (SIB1 ) of the second cell.

[0517] The request transmitted to the first central unit may comprise duration information indicating a validity duration of the configuration information associated with the wake-up signal.

[0518] The request transmitted to the first central unit may comprise an identifier associated with the second cell, a configuration for an on-demand SIB1 procedure towards the second cell, and a content of the on-demand SIB1 of the second cell.

[0519] The second central unit may receive, from the first central unit, a response message (in response to the transmitted request) indicating that the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell is being broadcasted on the first cell.

[0520] In block 1302, the second central unit transmits, to a second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

[0521] The SIB1 transmission may refer to a non-on-demand SIB1 transmission, such as a periodic legacy SIB1 transmission or broadcast.

[0522] The second central unit may determine to transmit the request for updating the master information block based on transmitting the request to the first central unit, or based on receiving the response message from the first central unit.

[0523] The second central unit may receive, from the second distributed unit, a response indicating an acknowledgement to the request for updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell.

[0524] The second central unit may receive, from the first central unit, the wake-up signal transmitted from a user device, wherein the wake-up signal indicates an identifier associated with the second cell; identify the second distributed unit based on the identifier indicated in the wake-up signal; and transmit, to the second distributed unit, a request for transmitting the on-demand SIB1 of the second cell. In other words, the second central unit may determine, based on the identification, to generate and / or transmit the request to the second distributed unit.

[0525] The second central unit may receive, from the second distributed unit, the configuration information associated with the wake-up signal; and transmit, to the first central unit, the configuration information associated with the wakeup signal, wherein the configuration information may indicate one or more conditions related to the wake-up signal.

[0526] The second central unit may receive, from the second distributed unit, the wake-up signal transmitted from a user device, wherein the wake-up signal indicates an identifier associated with the second cell; and transmit, to the second distributed unit, a request for transmitting an on-demand SIB1 of the second cell. In other words, the secondcentral unit may determine, based on the identifier, to generate and / or transmit the request to the second distributed unit.

[0527] The second central unit may transmit, to the second distributed unit, based on determining to deactivate the on-demand SIB1 transmission mode, a request for updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is deactivated for the second cell, or that the SIB1 transmission is activated for the second cell; and receive, from the second distributed unit, a response indicating an acknowledgement to the request for updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is deactivated for the second cell, or that the SIB1 transmission is activated for the second cell.

[0528] The second central unit may transmit, to the first central unit, a request to stop broadcasting the configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell; and receive, from the first central unit, a response message indicating that the broadcasting of the configuration information associated with the wake-up signal is stopped. The second central unit may determine to generate and / or transmit the request to stop the broadcasting, based on determining to deactivate the on-demand SIB1 mode of the second cell.

[0529] FIG. 14 illustrates a flow chart according to an example embodiment of a method for signaling to support on- demand SIB1. The method of FIG. 14 may be performed by the second distributed unit 105B of FIGS. 3 to 6 controlling the second cell 122.

[0530] Referring to FIG. 14, in block 1401, the second distributed unit receives, from a second central unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand system information block type one (SIB1) transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

[0531] In block 1402, the second distributed unit updates, based on the request, the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell.

[0532] The second distributed unit may transmit, to the second central unit, a response indicating an acknowledgement to the request for updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell. The second distributed unit may determine to generate and / or transmit the response based on updating the master information block successfully.

[0533] The second distributed unit may stop the SIB1 transmission for the second cell based on updating the master information block.

[0534] The second distributed unit may transmit, to the second central unit, configuration information associated with a wake-up signal for requesting an on-demand SIB1 of the second cell.

[0535] The second distributed unit may monitor for the wake-up signal based on the configuration information; receive the wake-up signal from a user device, wherein the wake-up signal indicates an identifier associated with the second cell; and transmit the wake-up signal to the second central unit.

[0536] The second distributed unit may receive, from the second central unit, a request for transmitting an on-demand SIB1 of the second cell; and transmit the on-demand SIB1 of the second cell based on the request. The transmission of the on-demand SIB1 may comprise, for example, broadcasting the on-demand SI B1, or transmitting the on-demand SIB1 via unicast or groupcast to the user device that requested the on-demand SIB1 via the wake-up signal (i.e., the transmission may be UE-specific or UE-group specific or a broadcast on the second cell).

[0537] The second distributed unit may receive, from the second central unit, a request for updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is deactivated for the second cell, or that an SIB1 transmission is activated for the second cell; update, based on the request, the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is deactivated for the second cell, or that the SIB1 transmission is activated for the second cell; transmit, to the second central unit, a response indicating an acknowledgement to the request for updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is deactivated for the second cell, or that the SIB1 transmission is activated for the second cell; and start the SIB1 transmission for the second cell based on updating the master information block to indicate at least one of: that the on-demand SIB1 transmission mode is deactivated for the second cell, or that the SIB1 transmission is activated for the second cell. The second distributed unit may determine to generate and / or transmit the response based on updating the master information block successfully.

[0538] FIG. 15 illustrates a flow chart according to an example embodiment of a method for signaling to support on- demand SIB1. The method of FIG. 15 may be performed by the user device 100 of FIGS. 3 to 11.

[0539] Referring to FIG. 15, in block 1501, the user device receives, from a first cell or from a second cell, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SI B1 of the second cell.

[0540] In other words, the configuration information may be received from the first cell controlled by a first distributed unit, or from the second cell controlled by a second distributed unit. The user device may be unaware of CUs and DUs, and it may only know its cell. Alternatively, the first cell and the second cell may be controlled by a base station (without a CU-DU split). Alternatively, the first cell may be controlled by a first base station (without a CU-DU split), and the second cell may be controlled by a second base station (without a CU-DU split) different from the first base station.

[0541] The user device may store the configuration information received from the first cell or from the second cell.

[0542] In block 1502, the user device receives, from the first cell or from the second cell, duration information indicating a validity duration of the configuration information associated with the wake-up signal.

[0543] In other words, the duration information may be received from the first cell controlled by the first distributed unit, or from the second cell controlled by the second distributed unit. Alternatively, the first cell and the second cell may be controlled by a base station (without a CU-DU split). Alternatively, the first cell may be controlled by a first base station (without a CU-DU split), and the second cell may be controlled by a second base station (without a CU- DU split) different from the first base station.

[0544] The validity duration may be related to a duration of an on-demand SIB1 transmission mode of the second cell.

[0545] In block 1503, the user device transmits the wake-up signal based on the configuration information and within the validity duration, wherein the wake-up signal indicates an identifier associated with the second cell.

[0546] In other words, the wake-up signal may be transmitted to the first cell controlled by the first distributed unit, or to the second cell controlled by the second distributed unit. Alternatively, the first cell and the second cell may be controlled by a base station (without a CU-DU split). Alternatively, the first cell may be controlled by a first base station (without a CU-DU split), and the second cell may be controlled by a second base station (without a CU-DU split) different from the first base station.

[0547] In block 1504, the user device receives the on-demand SIB1 of the second cell from the first cell or from the second cell.

[0548] In other words, the on-demand SIB1 of the second cell may be received from the first cell controlled by the first distributed unit, or from the second cell controlled by the second distributed unit. Alternatively, the first cell and the second cell may be controlled by a base station (without a CU-DU split). Alternatively, the first cell may be controlled by a first base station (without a CU-DU split), and the second cell may be controlled by a second base station (without a CU-DU split) different from the first base station.

[0549] The configuration information may indicate one or more conditions related to the wake-up signal. The user device may transmit the wake-up signal based on determining that the one or more conditions are fulfilled within the validity duration.

[0550] The one or more conditions may be related to at least one of: one or more radio conditions of the user device, or a presence of uplink data to be transmitted from the user device.

[0551] The user device may keep the configuration information without using the configuration information after the validity duration has expired, for example based on detecting that the validity duration has expired, or based on detecting that the first cell or the second cell is no longer broadcasting the configuration information.

[0552] Alternatively, the user device may discard the configuration information associated with the wake-up signal after the validity duration has expired, for example based on detecting that the validity duration has expired, or based on detecting that the first cell or the second cell is no longer broadcasting the configuration information.

[0553] Based on detecting that the validity duration has expired, the user device may attempt to acquire new configuration information associated with the wake-up signal for requesting the on-demand SIB1 of the second cell.

[0554] FIG. 16 illustrates a flow chart according to an example embodiment of a method for signaling to support on- demand SIB1. The method of FIG. 16 may be performed by the central unit 108 of FIGS. 7 to 11.

[0555] Referring to FIG. 16, in block 1601, the central unit receives, from a first distributed unit controlling a first cell or from a second distributed unit controlling a second cell, configuration information associated with a wake-up signal for requesting an on-demand system information block type one (SIB1 ) of the second cell.

[0556] The central unit may store the configuration information received from the first distributed unit or from the second distributed unit.

[0557] In block 1602, the central unit broadcasts the configuration information associated with the wake-up signal via the first distributed unit or via the second distributed unit. This may mean that the central unit prepares a system information message comprising the configuration information associated with the wake-up signal, and the systeminformation message is then broadcasted either by the first cell via the first distributed unit or by the second cell via the second distributed unit.

[0558] The configuration information may indicate one or more conditions related to the wake-up signal.

[0559] In block 1603, the central unit transmits, to the second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

[0560] The central unit may determine to generate and / or transmit the request for updating the master information block based on or in response to broadcasting the configuration information.

[0561] The central unit may receive, from the second distributed unit, a response indicating an acknowledgement to the request for updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell.

[0562] The central unit may receive, from the second distributed unit, duration information indicating a validity duration of the configuration information associated with the wake-up signal; and broadcast the duration information via the first distributed unit or via the second distributed unit.

[0563] The central unit may receive, from the second distributed unit, a configuration for an on-demand SIB1 procedure towards the second cell, and / or a content for the on-demand SIB1 of the second cell.

[0564] The central unit may receive the wake-up signal from a user device via the first distributed unit, wherein the wake-up signal indicates an identifier associated with the second cell; identify the configuration for the on-demand SIB1 procedure based on the identifier indicated in the wake-up signal; and transmit, to the first distributed unit, based on the identification, a request for transmitting the on-demand SIB1 of the second cell, wherein the request comprises the configuration for the on-demand SIB1 procedure, and the content of the on-demand SIB1 of the second cell.

[0565] Alternatively, the central unit may receive the wake-up signal from a user device via the first distributed unit, wherein the wake-up signal indicates an identifier associated with the second cell; identify the configuration for the on-demand SIB1 procedure based on the identifier indicated in the wake-up signal; and transmit, to the second distributed unit, based on the identification, a request for transmitting the on-demand SIB1 of the second cell.

[0566] Alternatively, the central unit may receive the wake-up signal from a user device via the second distributed unit, wherein the wake-up signal indicates an identifier associated with the second cell; identify the configuration for the on-demand SIB1 procedure based on the identifier indicated in the wake-up signal; and transmit, to the second distributed unit, based on the identification, a request for transmitting the on-demand SIB1 of the second cell.

[0567] The central unit may transmit, to the second distributed unit, based on determining to deactivate the on- demand SIB1 transmission mode for the second cell, a request for updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is deactivated for the second cell, or that the SIB1 transmission is activated for the second cell; and receive, from the second distributed unit, a response indicating an acknowledgement to the request for updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is deactivated for the second cell, or that the SIB1 transmission is activated for the second cell.

[0568] The central unit may, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell, stop broadcasting the configuration information associated with the wake-up signal via the first distributed unit or via the second distributed unit.

[0569] FIG. 17 illustrates a flow chart according to an example embodiment of a method for signaling to support on- demand SIB1. The method of FIG. 17 may be performed by the first distributed unit 105 of FIGS. 7 to 10 controlling the first cell 121.

[0570] Referring to FIG. 17, in block 1701, the first distributed unit receives, from a central unit, configuration information associated with a wake-up signal for requesting an on-demand system information block type one (SIB1 ) of a second cell.

[0571] The first distributed unit may transmit, to the central unit, the configuration information associated with the wake-up signal, prior to receiving the configuration information to be broadcasted.

[0572] In block 1702, the first distributed unit broadcasts the configuration information on the first cell. The first distributed unit may determine to broadcast the configuration information based on receiving the configuration information from the central unit.

[0573] The configuration information may indicate one or more conditions related to the wake-up signal.

[0574] The first distributed unit may receive, from the central unit, duration information indicating a validity duration of the configuration information associated with the wake-up signal; and broadcast the duration information on the first cell. The first distributed unit may determine to broadcast the duration information based on receiving the duration information from the central unit.

[0575] The first distributed unit may monitor for the wake-up signal based on the configuration information; receive the wake-up signal from a user device, wherein the wake-up signal indicates an identifier associated with the second cell; and transmit the wake-up signal to the central unit. The first distributed unit may determine to transmit the wakeup signal to the central unit based on the identifier indicated in the wake-up signal.

[0576] The first distributed unit may receive, from the central unit, a request for transmitting the on-demand SIB1 of the second cell, wherein the request comprises a configuration for an SIB1 procedure towards the second cell, and a content of the on-demand SIB1 of the second cell; and transmit the on-demand SIB1 of the second cell based on the configuration. The transmission of the on-demand SIB1 may comprise, for example, broadcasting the on-demand SIB1, or transmitting the on-demand SIB1 via unicast or groupcast to the user device that requested the on-demand SIB1 via the wake-up signal (i.e., the transmission may be UE-specific or UE-group specific or a broadcast on the first cell).

[0577] FIG. 18 illustrates a flow chart according to an example embodiment of a method for signaling to support on- demand SIB1. The method of FIG. 18 may be performed by the second distributed unit 105A of FIGS. 7 to 11 controlling the second cell 122.

[0578] Referring to FIG. 18, in block 1801, the second distributed unit receives, from a central unit, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand system information block type one (SIB1 ) transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

[0579] In block 1802, the second distributed unit updates, based on the request, the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell.

[0580] The second distributed unit may transmit, to the central unit, a response indicating an acknowledgement to the request for updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell. The second distributed unit may determine to generate and / or transmit the response based on updating the master information block successfully.

[0581] The second distributed unit may stop the SIB1 transmission of the second cell based on updating the master information block.

[0582] The second distributed unit may transmit, to the central unit, a configuration for an on-demand SIB1 procedure towards the second cell.

[0583] The second distributed unit may receive, from the central unit, a request for transmitting an on-demand SIB1 of the second cell; and transmit the on-demand SIB1 of the second cell based on the request. The transmission of the on-demand SIB1 may comprise, for example, broadcasting the on-demand SIB1 , or transmitting the on-demand SIB1 via unicast or groupcast to the user device that requested the on-demand SIB1 via the wake-up signal (i.e., the transmission may be UE-specific or UE-group specific or a broadcast on the second cell).

[0584] The second distributed unit may transmit, to the central unit, configuration information associated with a wakeup signal for requesting an on-demand SIB1 of the second cell, wherein the configuration information may indicate one or more conditions related to the wake-up signal.

[0585] The second distributed unit may transmit, to the central unit, duration information indicating a validity duration of the configuration information associated with the wake-up signal.

[0586] The second distributed unit may broadcast the configuration information on the second cell; and broadcast the duration information on the second cell.

[0587] The second distributed unit may monitor for the wake-up signal based on the configuration information; receive the wake-up signal from a user device, wherein the wake-up signal indicates an identifier associated with the second cell; and transmit the wake-up signal to the central unit. The second distributed unit may determine to transmit the wake-up signal to the central unit based on the identifier indicated in the wake-up signal.

[0588] The second distributed unit may receive, from the central unit, a request for updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is deactivated for the second cell, or that an SIB1 transmission is activated for the second cell; update, based on the request, the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is deactivated for the second cell, or that the SIB1 transmission is activated for the second cell; start the SIB1 transmission of the second cell based on updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is deactivated for the second cell, or that the SIB1 transmission is activated for the second cell; and transmit, to the central unit, a response indicating an acknowledgement to the request for updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is deactivated for the second cell, and that the SIB1 transmission is activated for the secondcell. The second distributed unit may determine to transmit the response based on updating the master information block successfully.

[0589] The blocks, related functions, and information exchanges (messages) described above by means of FIGS. 3 to 18 are in no absolute chronological order, and some of them may be performed simultaneously or in an order differing from the described one. Other functions can also be executed between them or within them, and other information may be sent, and / or other rules applied. Some of the blocks or part of the blocks or one or more pieces of information can also be left out or replaced by a corresponding block or part of the block or one or more pieces of information.

[0590] Herein the terms “first central unit” (or first CU), and “second central unit” (or second CU) are used to distinguish the central units, and they do not necessarily mean a specific order or specific identifiers of the central units.

[0591] Similarly, the terms “first distributed unit’ (or first DU) and “second distributed unit’ (or second DU) are used to distinguish the distributed units, and they do not necessarily mean a specific order or specific identifiers of the distributed units.

[0592] Similarly, the terms “first cell” and “second cell” are used to distinguish the cells, and they do not necessarily mean a specific order or specific identifiers of the cells.

[0593] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “oh’, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0594] FIG. 19 illustrates an example of an apparatus 1900 comprising means for performing one or more of the example embodiments described above. For example, the apparatus 1900 may be, or comprise, or be comprised in, the user device 100.

[0595] The apparatus 1900 may comprise a circuitry or a chipset applicable for realizing one or more of the example embodiments described above. For example, the apparatus 1900 may comprise at least one processor 1910. The at least one processor 1910 interprets instructions (e.g., computer program instructions) and processes data. The at least one processor 1910 may comprise one or more programmable processors. The at least one processor 1910 may comprise programmable hardware with embedded firmware and may, alternatively or additionally, comprise one or more application-specific integrated circuits (ASICs).

[0596] The at least one processor 1910 is coupled to at least one memory 1920. The at least one processor is configured to read and write data to and from the at least one memory 1920. The at least one memory 1920 may comprise one or more memory units. The memory units may be volatile or non-volatile. It is to be noted that there may be one or more units of non-volatile memory and one or more units of volatile memory or, alternatively, one or more units of non-volatile memory, or, alternatively, one or more units of volatile memory. Volatile memory may be for example random-access memory (RAM), dynamic random-access memory (DRAM) or synchronous dynamic random-access memory (SDRAM). Non-volatile memory may be for example read-only memory (ROM), programmable read-only memory (PROM), electronically erasable programmable read-only memory (EEPROM), flash memory, optical storage or magnetic storage. In general, memories may be referred to as non-transitory computer readable media. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible,not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). The at least one memory 1920 stores computer readable instructions that are executed by the at least one processor 1910 to perform one or more of the example embodiments described above. For example, non-volatile memory stores the computer readable instructions, and the at least one processor 1910 executes the instructions using volatile memory for temporary storage of data and / or instructions. The computer readable instructions may refer to computer program code.

[0597] The computer readable instructions may have been pre-stored to the at least one memory 1920 or, alternatively or additionally, they may be received, by the apparatus, via an electromagnetic carrier signal and / or may be copied from a physical entity such as a computer program product. Execution of the computer readable instructions by the at least one processor 1910 causes the apparatus 1900 to perform one or more of the example embodiments described above. That is, the at least one processor and the at least one memory storing the instructions may provide the means for providing or causing the performance of any of the methods and / or blocks described above.

[0598] In the context of this document, a “memory” or “computer-readable media” or “computer-readable medium” may be any non-transitory media or medium or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e. , tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[0599] The apparatus 1900 may further comprise, or be connected to, an input unit 1930. The input unit 1930 may comprise one or more interfaces for receiving input. The one or more interfaces may comprise for example one or more temperature, motion and / or orientation sensors, one or more cameras, one or more accelerometers, one or more microphones, one or more buttons and / or one or more touch detection units. Further, the input unit 1930 may comprise an interface to which external devices may connect to.

[0600] The apparatus 1900 may also comprise an output unit 1940. The output unit may comprise or be connected to one or more displays capable of rendering visual content, such as a light emitting diode (LED) display, a liquid crystal display (LCD) and / or a liquid crystal on silicon (LCoS) display. The output unit 1940 may further comprise one or more audio outputs. The one or more audio outputs may be for example loudspeakers.

[0601] The apparatus 1900 further comprises a connectivity unit 1950. The connectivity unit 1950 enables wireless connectivity to one or more external devices. The connectivity unit 1950 comprises at least one transmitter and at least one receiver that may be integrated to the apparatus 1900 or that the apparatus 1900 may be connected to. The at least one transmitter comprises at least one transmission antenna, and the at least one receiver comprises at least one receiving antenna. The connectivity unit 1950 may comprise an integrated circuit or a set of integrated circuits that provide the wireless communication capability for the apparatus 1900. Alternatively, the wireless connectivity may be a hardwired application-specific integrated circuit (ASIC). The connectivity unit 1950 may also provide means for performing at least some of the blocks or functions of one or more example embodiments described above. The connectivity unit 1950 may comprise one or more components, such as: power amplifier, digital front end (DFE), analog-to-digital converter (ADC), digital-to-analog converter (DAC), frequency converter, (de)modulator, and / or encoder / decoder circuitries, controlled by the corresponding controlling units.

[0602] It is to be noted that the apparatus 1900 may further comprise various components not illustrated in FIG. 19. The various components may be hardware components and / or software components.

[0603] FIG. 20 illustrates an example of an apparatus 2000 comprising means for performing one or more of the example embodiments described above. For example, the apparatus 2000 may be, or comprise, or be comprised in, the first central unit 108, the second central unit 108B, the first distributed unit 105, or the second distributed unit 105A, 105B.

[0604] The apparatus 2000 may comprise, for example, a circuitry or a chipset applicable for realizing one or more of the example embodiments described above. The apparatus 2000 may be an electronic device comprising one or more electronic circuitries. The apparatus 2000 may comprise a communication control circuitry 2010 such as at least one processor, and at least one memory 2020 storing instructions 2022 which, when executed by the at least one processor, cause the apparatus 2000 to carry out one or more of the example embodiments described above. Such instructions 2022 may, for example, include computer program code (software). The at least one processor and the at least one memory storing the instructions may provide the means for providing or causing the performance of any of the methods and / or blocks described above.

[0605] The processor is coupled to the memory 2020. The processor is configured to read and write data to and from the memory 2020. The memory 2020 may comprise one or more memory units. The memory units may be volatile or non-volatile. It is to be noted that there may be one or more units of non-volatile memory and one or more units of volatile memory or, alternatively, one or more units of non-volatile memory, or, alternatively, one or more units of volatile memory. Volatile memory may be for example random-access memory (RAM), dynamic random-access memory (DRAM) or synchronous dynamic random-access memory (SDRAM). Non-volatile memory may be for example read-only memory (ROM), programmable read-only memory (PROM), electronically erasable programmable read-only memory (EEPROM), flash memory, optical storage or magnetic storage. In general, memories may be referred to as non-transitory computer readable media. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). The memory 2020 stores computer readable instructions that are executed by the processor. For example, non-volatile memory stores the computer readable instructions, and the processor executes the instructions using volatile memory for temporary storage of data and / or instructions.

[0606] The computer readable instructions may have been pre-stored to the memory 2020 or, alternatively or additionally, they may be received, by the apparatus, via an electromagnetic carrier signal and / or may be copied from a physical entity such as a computer program product. Execution of the computer readable instructions causes the apparatus 2000 to perform one or more of the functionalities described above.

[0607] The memory 2020 may be implemented using any suitable data storage technology, such as semiconductorbased memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and / or removable memory. The memory may comprise a configuration database for storing configuration data, such as a current neighbour cell list, and, in some example embodiments, structures of frames used in the detected neighbour cells.

[0608] The apparatus 2000 may further comprise or be connected to a communication interface 2030, such as a radio unit, comprising hardware and / or software for realizing communication connectivity with one or more wireless communication devices according to one or more communication protocols. The communication interface 2030 comprises at least one transmitter (Tx) and at least one receiver (Rx) that may be integrated to the apparatus 2000or that the apparatus 2000 may be connected to. The communication interface 2030 may provide means for performing some of the blocks and / or functions (e.g., transmitting and receiving) for one or more example embodiments described above. The communication interface 2030 may comprise one or more components, such as: power amplifier, digital front end (DFE), analog-to-digital converter (ADC), digital-to-analog converter (DAC), frequency converter, (de)modulator, and / or encoder / decoder circuitries, controlled by the corresponding controlling units.

[0609] The communication interface 2030 provides the apparatus with communication capabilities to communicate in the wireless communication network. The communication interface may, for example, provide a radio interface to one or more UEs 100, 102. The apparatus 2000 may further comprise or be connected to another interface towards a core network 110, such as the network coordinator apparatus or AMF, and / or to other access nodes or DUs or CUs of the wireless communication network.

[0610] The apparatus 2000 may further comprise a scheduler that is configured to allocate radio resources. The scheduler may be configured along with the communication control circuitry 2010 or it may be separately configured.

[0611] It is to be noted that the apparatus 2000 may further comprise various components not illustrated in FIG. 20. The various components may be hardware components and / or software components.

[0612] As used in this application, the term “circuitry” may refer to one or more or all of the following: a) hardware- only circuit implementations (such as implementations in only analog and / or digital circuitry); and b) combinations of hardware circuits and software, such as (as applicable): i) a combination of analog and / or digital hardware circuit(s) with software / firmware and ii) any portions of hardware processor(s) with software (including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone, to perform various functions); and c) hardware circuit(s) and / or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (for example firmware) for operation, but the software may not be present when it is not needed for operation.

[0613] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0614] The techniques and methods described herein may be implemented by various means. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or combinations thereof. For a hardware implementation, the apparatus(es) of example embodiments may be implemented within one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), graphics processing units (GPUs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. For firmware or software, the implementation can be carried out through modules of at least one chipset (for example procedures, functions, and so on) that perform the functions described herein. The software codes may be stored ina memory unit and executed by processors. The memory unit may be implemented within the processor or externally to the processor. In the latter case, it can be communicatively coupled to the processor via various means, as is known in the art. Additionally, the components of the systems described herein may be rearranged and / or complemented by additional components in order to facilitate the achievements of the various aspects, etc., described with regard thereto, and they are not limited to the precise configurations set forth in the given figures, as will be appreciated by one skilled in the art.

[0615] It will be obvious to a person skilled in the art that, as technology advances, the inventive concept may be implemented in various ways within the scope of the claims. The embodiments are not limited to the example embodiments described above, but may vary within the scope of the claims. Therefore, all words and expressions should be interpreted broadly, and they are intended to illustrate, not to restrict, the embodiments.

Claims

CLAIMS1. A central unit comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the central unit at least to: receive, from a first distributed unit controlling a first cell or from a second distributed unit controlling a second cell, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1 , of the second cell; broadcast the configuration information associated with the wake-up signal via the first distributed unit or via the second distributed unit; and transmit, to the second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

2. The central unit of claim 1, wherein the configuration information indicates one or more conditions related to the wake-up signal.

3. The central unit of any preceding claim, wherein the central unit is caused to store the configuration information received from the first distributed unit or from the second distributed unit.

4. The central unit of any preceding claim, further being caused to: receive, from the second distributed unit, duration information indicating a validity duration of the configuration information associated with the wake-up signal; and broadcast the duration information via the first distributed unit or via the second distributed unit.

5. The central unit of any preceding claim, further being caused to: receive, from the second distributed unit, a configuration for an on-demand SIB1 procedure towards the second cell, and a content for the on-demand SIB1 of the second cell; receive the wake-up signal from a user device via the first distributed unit, wherein the wake-up signal indicates an identifier associated with the second cell; identify the configuration for the on-demand SIB1 procedure based on the identifier indicated in the wake-up signal; and transmit, to the first distributed unit, based on the identification, a request for transmitting the on-demand SIB1 of the second cell, wherein the request comprises the configuration for the on-demand SIB1 procedure, and the content of the on-demand SI B1 of the second cell.

6. The central unit of any of claims 1 to 4, further being caused to: receive, from the second distributed unit, a configuration for an on-demand SIB1 procedure towards the second cell;receive the wake-up signal from a user device via the first distributed unit, wherein the wake-up signal indicates an identifier associated with the second cell; identify the configuration for the on-demand SIB1 procedure based on the identifier indicated in the wake-up signal; and transmit, to the second distributed unit, based on the identification, a request for transmitting the on-demand SIB1 of the second cell.

7. The central unit of any of claims 1 to 4, further being caused to: receive, from the second distributed unit, a configuration for an on-demand SIB1 procedure towards the second cell; receive the wake-up signal from a user device via the second distributed unit, wherein the wake-up signal indicates an identifier associated with the second cell; identify the configuration for the on-demand SIB1 procedure based on the identifier indicated in the wake-up signal; and transmit, to the second distributed unit, based on the identification, a request for transmitting the on-demand SIB1 of the second cell.

8. The central unit of any preceding claim, further being caused to: receive, from the second distributed unit, a response indicating an acknowledgement to the request for updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is activated for the second cell, or that the SIB1 transmission is deactivated for the second cell.

9. The central unit of any preceding claim, further being caused to: transmit, to the second distributed unit, based on determining to deactivate the on-demand SIB1 transmission mode for the second cell, a request for updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is deactivated for the second cell, or that the SIB1 transmission is activated for the second cell; and receive, from the second distributed unit, a response indicating an acknowledgement to the request for updating the master information block of the second cell to indicate at least one of: that the on-demand SIB1 transmission mode is deactivated for the second cell, or that the SIB1 transmission is activated for the second cell.

10. The central unit of any preceding claim, further being caused to: based on determining to deactivate the on-demand SIB1 transmission mode for the second cell, stop broadcasting the configuration information associated with the wake-up signal via the first distributed unit or via the second distributed unit.

11. A method performed by a central unit, the method comprising:receiving, from a first distributed unit controlling a first cell or from a second distributed unit controlling a second cell, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1, of the second cell; broadcasting the configuration information associated with the wake-up signal via the first distributed unit or via the second distributed unit; and transmitting, to the second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

12. A non-transitory computer readable medium comprising program instructions which, when executed by a central unit, cause the central unit to perform at least the following: receiving, from a first distributed unit controlling a first cell or from a second distributed unit controlling a second cell, configuration information associated with a wake-up signal for requesting an on-demand system information block type one, SIB1, of the second cell; broadcasting the configuration information associated with the wake-up signal via the first distributed unit or via the second distributed unit; and transmitting, to the second distributed unit controlling the second cell, a request for updating a master information block of the second cell to indicate at least one of: that an on-demand SIB1 transmission mode is activated for the second cell, or that an SIB1 transmission is deactivated for the second cell.

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