GB2625108A

GB2625108A - Wake-up signal based cell re-selection

Info

Publication number: GB2625108A
Application number: GB2218347.9A
Authority: GB
Inventors: Tayyab Muhammad; Murat Gürsu Halit
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2022-12-07
Filing date: 2022-12-07
Publication date: 2024-06-12
Also published as: GB202218347D0; WO2024120743A1

Abstract

An apparatus for: receiving a WUS 303; comparing received power or received quality of the WUS to a threshold 304, 306; and determining whether to perform a cell re-selection procedure based at least on the comparison is disclosed. The apparatus may receive information 302 indicating the threshold. The cell re-selection procedure may comprise monitoring a synchronization signal block (SSB) on one or more cells. The apparatus may receive information indicating a priority order of frequency bands for monitoring WUSs including the WUS. The apparatus may determine an energy state of the apparatus wherein the energy state indicates an amount of energy available or predicted to be available at the apparatus and determines a frequency band to monitor based on the energy state. In another embodiment, an apparatus for transmitting information indicating at least a threshold for comparing received power or received quality of a wake-up signal to and performing a cell reselection procedure based at least on the comparison is disclosed.

Description

WAKE-UP SIGNAL BASED CELL RE-SELECTION FIELD

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

BACKGROUND

[0002] In wireless communication, user devices may have limited energy available. Thus, it is desirable to reduce the energy consumption of user devices.

BRIEF DESCRIPTION

[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 independent claims are to be interpreted as examples useful for understanding various embodiments.

[0004] According to an aspect there is provided an apparatus comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive a wake-up signal; compare received power or received quality of the wake-up signal to a threshold; and determine whether to perform a cell re-selection procedure based at least on the comparison.

[0005] According to another aspect, there is provided an apparatus comprising: means for receiving a wake-up signal; means for comparing received power or received quality of the wake-up signal to a threshold; and means for determining whether to perform a cell re-selection procedure based at least on the comparison.

[0006] According to another aspect, there is provided a method comprising: receiving a wake-up signal; comparing received power or received quality of the wake-up signal to a threshold; and determining whether to perform a cell re-selection procedure based at least on the comparison.

[0007] According to another aspect, there is provided a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a wake-up signal; comparing received power or received quality of the wake-up signal to a threshold; and determining whether to perform a cell re-selection procedure based at least on the comparison.

[0008] According to another aspect, there is provided a computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a wake-up signal; comparing received power or received quality of the wake-up signal to a threshold; and determining whether to perform a cell re-selection procedure based at least on the comparison.

[0009] According to another aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a wake-up signal; comparing received power or received quality of the wake-up signal to a threshold; and determining whether to perform a cell re-selection procedure based at least on the comparison.

[0010] According to another aspect, there is provided an apparatus comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: transmit information indicating at least a threshold for comparing received power or received quality of a wake-up signal to and performing a cell re-selection procedure based at least on the comparison.

[0011] According to another aspect, there is provided an apparatus comprising: means for transmitting information indicating at least a threshold for comparing received power or received quality of a wake-up signal to and performing a cell re-selection procedure based at least on the comparison.

[0012] According to another aspect, there is provided a method comprising: transmitting information indicating at least a threshold for comparing received power or received quality of a wake-up signal to and performing a cell re-selection procedure based at least on the comparison.

[0013] According to another aspect, there is provided a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: transmitting information indicating at least a threshold for comparing received power or received quality of a wake-up signal to and performing a cell re-selection procedure based at least on the comparison.

[0014] According to another aspect, there is provided a computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: transmitting information indicating at least a threshold for comparing received power or received quality of a wake-up signal to and performing a cell re-selection procedure based at least on the comparison.

[0015] According to another aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: transmitting information indicating at least a threshold for comparing received power or received quality of a wake-up signal to and performing a cell re-selection procedure based at least on the comparison.

LIST OF DRAWINGS

[0016] In the following, various example embodiments will be described in greater detail with reference to the accompanying drawings, in which FIG. 1 illustrates an example of a cellular communication network; FIG. 2 illustrates power consumption profiles for discontinuous reception and wake-up signal; FIG. 3 illustrates a signaling diagram; FIG. 4 illustrates a flow chart; FIG. 5 illustrates a signaling diagram; FIG. 6 illustrates a flow chart; FIG. 7 illustrates a signaling diagram; FIG. 8 illustrates a flow chart; FIG. 9 illustrates a flow chart; FIG. 10 illustrates a flow chart; FIG. 11 illustrates an example of an apparatus; and FIG. 12 illustrates an example of an apparatus.

DETAILED DESCRIPTION

[0017] 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.

[0018] In the following, different example embodiments will be described using, as an example of an access architecture to which the example embodiments may be applied, a radio access architecture based on long term evolution advanced (LIE Advanced, LIE-A), new radio (NR, 5G), beyond 5G, or sixth generation (6G) without restricting the example embodiments to such an architecture, however. It is obvious for a person skilled in the art that the example embodiments may also be applied to other kinds of communications networks having suitable means by adjusting parameters and procedures appropriately. Some examples of other options for suitable systems may be the universal mobile telecommunications system (UMTS) radio access network (UTRAN or E-UTRAN), long term evolution (LIE, substantially the same as E-UTRA), wireless local area network (WLAN or Wi-Fi), worldwide interoperability for microwave access (WiMAX), Bluetoothg, personal communications services (PCS), ZigBeeg, wideband code division multiple access (WCDMA), systems using ultra-wideband (UWB) technology, sensor networks, mobile ad-hoc networks (MANETs) and Internet Protocol multimedia subsystems (IMS) or any combination thereof.

S

[0019] FIG. 1 depicts examples of simplified system architectures showing some elements and functional entities, all being logical units, whose implementation may differ from what is shown. The connections shown in FIG. 1 are logical connections; the actual physical connections may be different. It is apparent to a person skilled in the art that the system may also comprise other functions and structures than those shown in FIG. 1.

[0020] The example embodiments are not, however, restricted to the system given as an example but a person skilled in the art may apply the solution to other communication systems provided with necessary properties.

[0021] The example of FIG. 1 shows a part of an exemplifying radio access network.

[0022] FIG. 1 shows user devices 100 and 102 configured to be in a wireless connection on one or more communication channels in a radio cell with an access node (AN) 104, such as an evolved Node B (abbreviated as eNB or eNodeB) or a next generation Node B (abbreviated as gNB or gNodeB), providing the radio cell. The physical link from a user device to an access node may be called uplink (UL) or reverse link, and the physical link from the access node to the user device may be called downlink (DL) or forward link. A user device may also communicate directly with another user device via sidelink (SL) communication. It should be appreciated that access nodes or their functionalities may be implemented by using any node, host, server or access point etc. entity suitable for such a usage.

[0023] A communication system may comprise more than one access node, in which case the access nodes may also be configured to communicate with one another over links, wired or wireless, designed for the purpose. These links may be used for signaling purposes and also for routing data from one access node to another. The access node may be a computing device configured to control the radio resources of communication system it is coupled to. The access node may also be referred to as a base station, a base transceiver station (BTS), an access point or any other type of interfacing device including a relay station capable of operating in a wireless environment The access node may include or be coupled to transceivers. From the transceivers of the access node, a connection may be provided to an antenna unit that establishes hi-directional radio links to user devices. The antenna unit may comprise a plurality of antennas or antenna elements. The access node may further be connected to a core network 110 [CM or next generation core NGC). Depending on the deployed technology, the counterpart that the access node may be connected to on the CN side may be a serving gateway (S-GW, routing and forwarding user data packets), packet data network gateway (P-GW) for providing connectivity of user devices to external packet data networks, user plane function (UPF), mobility management entity (MME), or an access and mobility management function (AMF), etc. [0024] The user device illustrates one type of an apparatus to which resources on the air interface may be allocated and assigned, and thus any feature described herein with a user device may be implemented with a corresponding apparatus, such as a relay node.

[0025] An example of such a relay node may be a layer 3 relay (self-backhauling relay) towards the access node. The self-backhauling relay node may also be called an integrated access and backhaul (IAB) node. The IAB node may comprise two logical parts: a mobile termination (MT) part, which takes care of the backhaul link(s) (i.e., link(s) between IAB node and a donor node, also known as a parent node) and a distributed unit (DU) part, which takes care of the access link(s), i.e., child link(s) between the IAB node and user device(s), and/or between the 1AB node and other 1AB nodes (multi-hop scenario).

[0026] Another example of such a relay node may be a layer 1 relay called a repeater. The repeater may amplify a signal received from an access node and forward it to a user device, and/or amplify a signal received from the user device and forward it to the access node.

[0027] The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, or user equipment (UE) just to mention but a few names or apparatuses. The user device may refer to a portable computing device that includes wireless mobile communication devices operating with or without a subscriber identification module (SIM), including but not limited to, the following types of devices: a mobile station (mobile phone), smartphone, personal digital assistant (PDA), handset, device using a wireless modem (alarm or measurement device, etc.), laptop and/or touch screen computer, tablet, game console, notebook, multimedia device, reduced capability (RedCap) device, wireless sensor device, or any device integrated in a vehicle.

[0028] It should be appreciated that a user device 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. A user device may also be a device having capability to operate in 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. The user device may also utilize cloud. In some applications, a user device may comprise a small portable or wearable device with radio parts (such as a watch, earphones or eyeglasses) and the computation may be carried out in the cloud or in another user device. The user device (or in some example embodiments a layer 3 relay node) may be configured to perform one or more of user equipment functionalities.

[0029] Various techniques described herein may also be applied to a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the implementation and exploitation of massive amounts of interconnected 1CT devices (sensors, actuators, processors microcontrollers, etc.) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question may have inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals.

[0030] Additionally, although the apparatuses have been depicted as single entities, different units, processors and/or memory units (not all shown in FIG. 1) may be implemented.

[0031] SG enables using multiple input -multiple output (MIMO) antennas, many more base stations or nodes than the LTE (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 5 and/or spectrum available. SG mobile communications 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. Sc may have multiple radio 10 interfaces, namely below 6GHz, cmWave and mmWave, and also being integrable with existing legacy radio access technologies, such as the LTE. Integration with the LTE may be implemented, for example, as a system, where macro coverage may be provided by the LTE, and SG radio interface access may come from small cells by aggregation to the LTE. In other words, SG may support both inter-RAT operability (such as LTE-SG) and inter-R1 operability (inter-radio interface operability, such as below 6GHz -cmWave -mm Wave]. One of the concepts considered to be used in SG networks may be network slicing in which multiple independent and dedicated virtual sub-networks (network instances) may be created within the substantially same infrastructure to run services that have different requirements on latency, reliability, throughput and mobility.

[0032] The current architecture in LTE networks may be fully distributed in the radio and fully centralized in the core network. The low latency applications and services in SG may need to bring the content close to the radio which leads to local break out and multi-access edge computing (MEC). SG may enable analytics and knowledge generation to occur at the source of the data. This approach may need leveraging resources that may not be continuously connected to a network such as laptops, smartphones, tablets and sensors. MEC may provide a distributed computing environment for application and service hosting. It may also have the ability to store and process content in close proximity to cellular subscribers for faster response time. Edge computing may cover a wide range of technologies such as wireless sensor networks, mobile data acquisition, mobile signature analysis, cooperative distributed peer-to-peer ad hoc networking and processing also classifiable as local cloud/fog computing and grid/mesh computing, dew computing, mobile edge computing, cloudlet, distributed data storage and retrieval, autonomic self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and/or latency critical), critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, healthcare applications).

[0033] The communication system may also be able to communicate with one or more other networks 113, such as a public switched telephone network or the Internet, or utilize services provided by them. The 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 communication system may also comprise a central control entity, or the like, providing facilities for networks of different operators to cooperate for example in spectrum sharing.

[0034] An access node may also be split into: a radio unit (RU) comprising a radio transceiver (MX), i.e., a transmitter (Tx) and a receiver (Rx); one or more distributed units (DUs) 105 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 (also known as a centralized unit) that may be used for non-real-time L2 and Layer 3 (L3) processing. The CU 108 may be connected to the one or more DUs 105 for example via an Fl interface. Such a split 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).

[0035] The CU 108 may be defined as a logical node hosting higher layer protocols, such as radio resource control (RRC), service data adaptation protocol (SDAP) and/or packet data convergence protocol (PDCP), of the access node. The DU 105 may be defined as a logical node hosting radio link control (RLC), medium access control (MAC) and/or physical (PH?] layers of the access node. The operation of the DU may be at least partly controlled by the CU. The CU may comprise a control plane (CU-CP), which may be defined as a logical node hosting the RRC and the control plane part of the PDCP protocol of the CU for the access node. The CU may further comprise a user plane (CU-UP), which may be defined as a logical node hosting the user plane part of the PDCP protocol and the SDAP protocol of the CU for the access node.

[0036] Cloud computing platforms may also be used to run the CU 108 and/or DU 105. The CU may run in a cloud computing platform, which may be referred to as a virtualized CU (vCU). In addition to the vCU, there may also be a virtualized DU (vDU) running in a cloud computing platform. Furthermore, there may also be a combination, where the DU may use so-called bare metal solutions, for example application-specific integrated circuit (AS1C) or customer-specific standard product (CSSP) system-on-a-chip (SoC) solutions. It should also be understood that the distribution of functions between the above-mentioned access node units, or different core network operations and access node operations, may differ.

[0037] Edge cloud may be brought into radio access network (RAN) 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 server, host or node operationally coupled to a remote radio head (RRH) or a radio unit (RU), or an access node comprising radio parts. It is also possible that node operations may be distributed among a plurality of servers, nodes or hosts. Application of cloudRAN architecture enables RAN real-time functions being carried out at the RAN side (e.g., in a DU 105) and non-real-time functions being carried out in a centralized manner (e.g., in a CU 108).

[0038] It should also be understood that the distribution of functions between core network operations and access node operations may differ from that of the LTE or even be non-existent Some other technology advancements that may be used include big data and all-IP, which may change the way networks are being constructed and managed. 5G (or new radio, NR) networks may be designed to support multiple hierarchies, where MEC servers may be placed between the core and the access node. It should be appreciated that MEC may be applied in 4G networks as well.

[0039] 5G may also utilize non-terrestrial communication, for example satellite communication, to enhance or complement the coverage of 5G service, for example by providing backhauling. Possible use cases may be providing service continuity for machine-to-machine (NI2M) or Internet of Things (loT) devices or for passengers on board of vehicles, or ensuring service availability for critical communications, and future railway/maritime/aeronautical communications.

Satellite communication may utilize geostationary earth orbit [CEO) satellite systems, but also low earth orbit (LEO) satellite systems, in particular mega-constellations (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 node or by an access node 104 located on-ground or in a satellite.

[0040] 6G 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.

[0041] It is obvious for a person skilled in the art that the depicted system is only an example of a part of a radio access system and in practice, the system may comprise a plurality of access nodes, the user device may have access to a plurality of radio cells and the system may also comprise other apparatuses, such as physical layer relay nodes or other network elements, etc. At least one of the access nodes may be a Home eNodeB or a Home gNodeB.

[0042] Additionally, in a geographical area of a radio communication system, 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) of FIG. 1 may provide any kind of these cells. A cellular radio system may be implemented as a multilayer network including several kinds of radio cells. In multilayer 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 network structure.

[0043] For fulfilling the need for improving the deployment and performance of communication systems, the concept of "plug-and-play" access nodes may be introduced. A 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, or HNB-GW (not shown in FIG. 1). An HNB-GW, which may be installed within an operator's network, may aggregate traffic from a large number of Home eNodeBs or Home gNodeBs back to a core network.

[0044] Currently, UEs may need to periodically wake up once per discontinuous reception (DRX) cycle. When the UE wakes up, the power consumption of the UE increases. If UEs wake up only when they are triggered (e.g., via paging), power consumption may be reduced. This can be achieved by using a wake-up signal (WUS) to trigger the main radio of the UE, and a separate receiver (wake-up receiver) that can monitor wake-up signals with ultra-low power consumption. The power consumption for monitoring wake-up signals depends on the wake-up signal design and the hardware module of the wake-up receiver used for signal detecting and processing.

[0045] The WUS operating principle is that in every wake-up cycle, called w-cycle, the wake-up receiver (WURx) monitors a set of specified subcarriers for a short duration of time to determine whether it receives a wake-up indicator (WI) or not. Through the WI, the network may inform the UE to decode the physical downlink control channel (PDCCH) with a specified time offset called w-offset Once the WURx successfully detects the WI, the baseband processor (BBP) will be switched on. After that, the BBP decodes the PDCCH messages at an active state for a preconfigured on-duration period, followed by the initiation of its inactivity timer. After the inactivity timer is initiated, and if a new PDCCH message is received before the timer expiration, the BBP re-initiates its inactivity timer. However, if there is no PDCCH message received before the expiration of the inactivity timer, a sleep period starts, the UE switches to its sleep state, and WURx operates according to its w-cycle.

[0046] In other words, in the WURx approach, the UE is in hibernation mode unless it is paged by the network or has a message to exchange. No power is consumed except for monitoring whether the UE is paged. To page a UE, the network may broadcast a wake-up signal, including the UE's unique address, to all UEs in its coverage. The power consumption ofWURx lies in the microwatt domain, whereas the UE (e.g., loT device) may consume at least several milliwatts. For such ultra-low-power devices, harvesting energy from the environment may provide enough power (e.g., around 1 microwatt), to keep the WURx charged in order to operate in a self-sustainable manner.

[0047] FIG. 2 illustrates representative power consumption profiles 201, 202 of DRX and WUS. Block 201 illustrates the power consumption profile of DRX, and block 202 illustrates the power consumption profile of WUS. In FIG. 2, the black areas indicate power consumption under scheduled PDCCH. As can be seen in FIG. 2, the WUS reduces the UE energy consumption compared to baseline DRX, as the energy consumption related to decoding unscheduled PDCCHs is avoided.

Moreover, since the w-cycle can be short without essentially increasing the energy consumption, the buffering delay can be reduced compared to DRX.

[0048] There may be some use cases, such as smart logistics, smart warehouse, wearables, etc., where it may be beneficial to provide a simplified mobility procedure. For mobility among neighboring cells, idle mode UEs may rely on a cell re-selection procedure. The purpose of the cell re-selection procedure is to ensure that the idle mode UE is always camped on a suitable cell. The network may influence this procedure by adjusting the broadcast information of individual cells in different system information blocks (SIBs). These SIBs may comprise configuration parameters that the UE can use to evaluate the radio quality of the currently camped-on cell and neighboring cells to switch the camped-on cell, as the UE moves across the borders of different cells. Currently, the cell re-selection procedure may be slice-agnostic, i.e., the UE may not consider the slice support of the neighboring cells while evaluating the neighbor cells.

[0049] Passive loT devices and reduced capability (RedCap) devices may rely on energy harvesting. Energy harvesting may be considered in several use cases, in which a UE can harvest and store a limited amount of energy from the environment. Some examples of RedCap devices may include (but are not limited to) industrial wireless sensors, video surveillance cameras, and wearables (e.g., smart watches, rings, ellealth-related devices, personal protection equipment, medical monitoring devices, etc.). RedCap devices may also be referred to as NR-Lite devices or NR-Light devices.

[0050] Passive loT devices (or a part of a UE operating, or part of a UE or device configured to operate as a passive loT device) may support communication with a reader UE via reflection (backscattering) or similar, which may be supported by very low-complexity hardware. A passive loT device may harvest energy from the environment, for example from radio frequency (RF) signals, solar energy, vibration, heat energy, etc., to power the passive loT device for self-sustainable communication. A passive loT device may potentially be equipped with a small-capacity battery or capacitor that may be charged with the harvested energy. Passive loT devices may also be referred to as passive devices or tags or energy harvesting devices herein.

[0051] For example, sensors powered by solar energy are becoming popular, especially for small sensors deployed outdoors for monitoring. The maximum transmit power of such passive loT devices may also be significantly smaller due to smaller battery size or absence of battery. For example, passive loT devices may be used for delay-tolerant loT-type of traffic (e.g., reporting temperature, traffic condition, etc). For energy harvesting devices, the focus may be on using energy when it is available and not necessarily on saving energy all the time.

[0052] The following areas may need enhancement to support passive loT devices: 1) simplified and adaptive procedures for operation with intermittently available energy and interrupted connections (e.g., random-access procedure, RRC protocol/RRC states handling, cell (re-)selection), 2) light-weight protocol for ultra-low power consumption, and 3] energy-neutral sustainable operation of devices.

[0053] Currently, a UE may perform a cell re-selection procedure based on synchronization signal block (SSB) measurements. However, monitoring the SSBs constantly is costly in terms of power consumption. Thus, in some example embodiments, WUS is introduced to the cell re-selection procedure in order to reduce the UE power consumption.

[0054] Some example embodiments provide a cell re-selection procedure that integrates the wake-up signal into the evaluation methodology. For example, the UE may be configured with a WUS threshold by the broadcast signaling from the network in order to determine whether to perform a cell re-selection procedure. Some example embodiments may reduce monitoring of SSBs by performing the cell re-selection procedure when the WUS related value is under the WUS threshold, and thus reduce power consumption of the UE.

[0055] Some example embodiments are described below using principles and terminology of 5G technology without limiting the example embodiments to 5G communication systems, however.

[0056] FIG. 3 illustrates a signaling diagram according to an example embodiment. In this example embodiment, a user device (i.e., UE) is configured to monitor the WUS at a cell (e.g., a first cell, a serving cell). The user device monitors the WUS received power or received quality and compares it to a threshold in order to detect if the WUS received power or received quality is below the threshold. If that is the case, the user device initiates an SSB-based cell re-selection procedure.

Otherwise, the user device does not initiate the cell re-selection procedure, and the user device keeps monitoring the WUS according to w-cycle. In case the user device does not receive WUS for a certain amount of time, the user device may fall back to SSB-based cell re-selection.

[0057] Referring to FIG. 3, in block 301, the user device is camping on a first cell (cell 1). In other words, the first cell may be the serving cell of the user device.

[0058] In block 302, the user device receives information, for example system information, on the first cell, wherein the information indicates one or more WUS-specific cell re-selection parameters. The information may be transmitted by a network node (e.g., gNB or TRP) that provides the first cell.

[0059] For example, the one or more WUS-specific cell re-selection parameters may comprise at least a threshold for received power or received quality of a WUS on the first cell. The information may indicate to perform a cell re-selection procedure, if the received power or the received quality of the WUS on the first cell is below or equal to the threshold.

[0060] Alternatively, the threshold may be pre-defined at the user device (e.g., defined in specifications or hard-coded to the user device), in which case it may not be necessary for the first cell to transmit the information.

[0061] In one example, the WUS-based cell re-selection may be used in the cell center. In other words, the user device may monitor for the wake-up signal (instead of SSB) based on determining that the user device is located at a center area of the serving cell (first cell). When the user device is located at the cell center area, cell re-selection is not likely to be needed soon, and thus WUS monitoring may be used instead of SSB monitoring in order to reduce power consumption. In case the user device is located outside of the cell center area, the user device monitors not the WUS but the SSB in order to decide whether to perform the cell re-selection or not. The user device may determine whether it is located at the cell center area based on radio measurements. For example, if the received power or received quality of a signal received on the cell is high, for example above a radio threshold, then the user device may determine that it is located at the center area of the cell.

[0062] In another example, the WUS-based cell re-selection may be based on previous SSB measurements or location of the user device. In other words, the user device may monitor for the wake-up signal (instead of SSB) based on received power or received quality of one or more synchronization signal blocks previously received on the serving cell (first cell). For example, if the received power or the received quality of the one or more SSBs is high, i.e., above a certain threshold, the user device may monitor for the wake-up signal instead of monitoring SSB.

[0063] In block 303, a first wake-up signal is transmitted on the first cell to the user device, and the user device receives the first wake-up signal. In other words, the first wake-up signal may be transmitted by the network node (e.g., gNB or TRP) that provides the first cell.

[0064] In block 304, the user device may determine whether to perform a cell re-selection procedure by comparing the received power or the received quality of the first wake-up signal to the threshold. In this example, the received power or the received quality of the first wake-up signal is above the threshold, and thus the user device determines to not perform the cell re-selection procedure and the user device may switch to the sleep mode based on the w-cycle. [0065] Comparing the received power or the received quality to the threshold may mean comparing a measured received power value or a measured received quality value to the threshold, wherein the threshold indicates a threshold value for the received power or the received quality of the WUS.

[0066] In block 305, a second wake-up signal is transmitted on the first cell to the user device. In other words, the second wake-up signal may be transmitted by the network node (e.g., gNB or TRP) that provides the first cell. The second wake-up signal may be transmitted at a different time than the first wake-up signal. The user device receives the second wake-up signal.

[0067] In block 306, the user device determines whether to perform the cell re-selection procedure by comparing the received power or the received quality of the second wake-up signal to the threshold. In this example, the user device determines to perform the cell re-selection procedure based at least on the comparison indicating that the received power or the received quality of the second wake-up signal is equal to or below the threshold.

[0068] The cell re-selection procedure may comprise at least monitoring a synchronization signal block (SSB) on one or more radio cells.

[0069] In block 307, based on determining to perform the cell re-selection procedure, the user device starts monitoring synchronization signal blocks on the one or more cells, for example the first cell and a second cell (cell 2).

The second cell may be a neighbor cell of the first cell. For example, the first cell may operate on frequency range one (FR1), and the second cell may operate on frequency range two (FR2), or vice versa. In addition, a single gNB may manage the first cell and the second cell. Alternatively, the first cell and the second cell may be managed by different gNBs, respectively.

[0070] Herein 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.

[0071] In block 308, the user device receives a first SSB on the first cell. 15 The first SSB may be transmitted by the network node (e.g., gNB or TRP) that provides the first cell.

[0072] In block 309, the user device receives a second SSB on the second cell. The second SSB may be transmitted by the network node (e.g., gNB or TRP) that provides the second cell. This network node may be the same or different than the network node that provides the first cell.

[0073] The user device may further receive other SSBs on other cells (not shown in FIG. 3).

[0074] In block 310, the user device determines that one of the one or more cells is the best ranked cell. For example, the second cell may be determined as the best ranked cell among the one or more cells. More specifically, the user device may measure received power or received quality of the first SSB and the second SSB. If the received power or the received quality of the second SSB is higher than the received power or the received quality of the first SSB, then the user device may determine that the second cell is the best ranked cell.

[0075] In block 311, the user device determines whether the second cell is a suitable cell to camp on.

[0076] For example, if the user device is operating in standalone nonpublic network (SNPN) access mode, the second cell may be considered as suitable if the following conditions are fulfilled: 1) the second cell is part of either the selected public land mobile network (PLMN) or the registered PLMN or PLMN of 5 the Equivalent PLMN list 2) and for that PLMN either: the PLMN ID of that PLMN is broadcast by the second cell with no associated closed access group (GAG) IDs and GAG-only indication in the user device for that PLMN is absent or false; 3) allowed GAG list in the user device for that PLMN includes a GAG-ID broadcast by the second cell for that PLMN; 4) the cell selection criteria are fulfilled; and 10 according to the latest information provided by non-access stratum (NAS): 5) the second cell is not barred; and 6) the second cell is part of at least one tracking area (TA) that is not part of the list of "Forbidden Tracking Areas for Roaming", which belongs to a PLMN that fulfils the first condition above.

[0077] If the user device is operating in SNPN Access Mode, the second cell may be considered as suitable if the following conditions are fulfilled: 1) the second cell is part of either the selected SNPN or the registered SNPN of the user device; 2) the cell selection criteria are fulfilled; and according to the latest information provided by NAS: 3) the second cell is not barred; and 4) the second cell is part of at least one TA that is not part of the list of "Forbidden Tracking Areas for Roaming" which belongs to either the selected SNPN or the registered SNPN of the user device.

[0078] In block 312, the user device camps on the second cell based on determining that the second cell is a suitable cell to camp on.

[0079] In case the second cell is not determined to be suitable, then the user device may measure another frequency band to find another best ranked cell in the other frequency band. For example, there may be two different best ranked cells in two different frequency bands.

[0080] FIG. 4 illustrates a flow chart according to an example embodiment of a method performed by an apparatus. For example, the apparatus 30 may be, or comprise, or be comprised in, a user device. The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, or user equipment (UE). The user device may correspond to one of the user devices 100, 102 of FIG. 1 or the user device of FIG. 3.

[0081] This example embodiment enables the apparatus to initiate a cell re-selection procedure, if the serving cell WUS strength/quality is below or equal to a certain threshold.

[0082] Referring to FIG. 4, in block 401, the apparatus performs WUS monitoring at the serving cell of the apparatus. In other words, the apparatus monitors for at least one wake-up signal on the serving cell.

[0083] In block 402, the apparatus receives at least one wake-up signal on the serving cell based on the monitoring, and compares received power or received quality of the at least one wake-up signal to a first threshold in order to determine whether to perform a cell re-selection procedure. The apparatus may measure the received power or the received quality based on the received wake-up signal.

[0084] If the received power or the received quality of the wake-up signal is above the first threshold (block 402: no), then the process may return to block 401, i.e., the apparatus determines there is no need to perform a cell re-selection procedure and continues the WUS monitoring at the serving cell based on the w-cycle.

[0085] If the received power or the received quality of the wake-up signal is equal to or below the first threshold (block 402: yes), in block 403, the apparatus determines to perform the cell re-selection procedure, and thus the apparatus performs SSB monitoring at the serving cell. In other words, the cell re-selection procedure may comprise at least the SSB monitoring. The apparatus receives an SSB on the serving cell based on the SSB monitoring.

[0086] In block 404, the apparatus compares received power or received quality of the SSB to a second threshold.

[0087] If the received power or the received quality of the SSB received on the serving cell is above the second threshold (block 404: no), then the process may return to block 401, i.e., the apparatus continues the WUS monitoring.

[0088] In block 405, if the received power or the received quality of the SSB received on the serving cell is below or equal to the second threshold (block 404: yes), the apparatus performs SSB monitoring at one or more neighbor cells of the serving cell. Based on the SSB monitoring, the apparatus receives an SSB on the one or more neighbor cells (e.g., one SSB per cell).

[0089] In block 406, the apparatus ranks a plurality of cells, i.e., the serving cell and the one or more neighbor cells, based on the received power or the received quality of the SSBs received on the plurality of cells.

[0090] In block 407, the apparatus selects a cell from the plurality of cells based on the ranking. For example, the apparatus may select the cell with the highest SSB received power or quality among the plurality of cells.

[0091] In block 408, the apparatus determines whether the selected cell is suitable to camp on.

[0092] In block 409, based on determining that the selected cell is suitable to camp on (block 408: yes), the apparatus camps on the selected cell.

[0093] Alternatively, if the apparatus determines that the selected cell is not suitable (block 408: no), then the process may return to block 405, i.e., the apparatus may measure more cells (e.g., on a different frequency band) and find a suitable cell eventually.

[0094] FIG. 5 illustrates a signaling diagram according to another example embodiment In this example embodiment, the user device may be provided with WUS cell re-selection information. The WUS cell re-selection information may comprise WUS frequency priorities, as well as the time-domain and frequency-domain locations of one or more wake-up signals transmitted on one or more neighboring cells. The WUS time-domain and frequency-domain locations of neighboring cells may be the same or different.

[0095] The frequency priorities may indicate the order in which frequencies (e.g., frequency bands or frequency sub-bands) the user device should monitor the WUS. The user device may monitor the WUS by starting from the highest priority frequency band to the lowest priority frequency band. In case no cell in a specific frequency band supports WUS (i.e., the user device cannot receive any WUS in that specific frequency band), the user device may de-prioritize the specific frequency band and monitors the next priority frequency band.

[0096] The user device may monitor the WUS received power/quality and compare it to a threshold to detect if the WUS of the measured cell is above a threshold. If that is the case, the user device selects the cell as a candidate cell and also measures the SSB for the same cell to determine if the candidate cell is a suitable cell. If no WUS is found on any of the cells in the measured frequency bands, the user device may fall back to SSB-based cell re-selection.

[0097] Referring to FIG. 5, in block 501, the user device is camping on a first cell (cell 1). In other words, the first cell may be the serving cell of the user device.

[0098] In block 502, the WUS cell re-selection information is received by the user device via the first cell (e.g., in system information broadcast), wherein the WUS cell re-selection information indicates one or more WUS-specific cell re-selection parameters. The WUS cell re-selection information may be transmitted by a network node (e.g., gNB or TRP) that provides the first cell.

[0099] For example, the one or more WUS-specific cell re-reselection parameters may comprise at least a WUS threshold for received power or received quality of WUS from neighbor cells. Alternatively, the threshold may be pre-defined at the user device (e.g., defined in specifications or hard-coded to the user device).

[0100] The one or more WUS-specific parameters may further indicate a priority order of frequency bands for monitoring wake-up signals for the WUSspecific cell re-selection.

[0101] The one or more WUS-specific parameters may further indicate one or more WUS ranking parameters for the WUS-specific cell re-selection. For example, the one or more WUS ranking parameters may indicate hysteresis for the serving cell and possibly an offset to prioritize or de-prioritize the rank of the neighbor cells.

[0102] In block 503, the user device monitors for wake-up signals on a plurality of radio cells by starting from a highest priority frequency band among the frequency bands according to the priority order. As a non-limiting example, FR1 may be the highest priority frequency band for WUS-specific cell re-selection. [0103] In block 504, a first wake-up signal is transmitted on the first cell to the user device. The first wake-up signal may be transmitted by the network node (e.g., gNB or TRP) that provides the first cell. The user device receives the first wake-up signal. For example, the first cell may operate on FR1.

[0104] In block 505, the user device compares received WUS power or received quality of the WUS to the threshold. In this case, the user device may determine that no cell on the highest priority frequency band is above the WUS threshold.

[0105] In block 506, the user device monitors for wake-up signals on the plurality of radio cells on a different frequency band than the highest priority frequency band based on the priority order, when the user device fails to receive any wake-up signals on the highest priority frequency band. For example, the user device may continue the monitoring on the frequency band with the second highest priority according to the priority order. In other words, the user device may de-prioritize the highest priority frequency band (e.g., FR1). As a non-limiting example, FR2 may be the frequency band with the second highest priority for WUSspecific cell re-selection.

[0106] In block 507, one or more second wake-up signals are transmitted to the user device via one or more radio cells of the different frequency band. The one or more second wake-up signals may be transmitted by a network node (e.g., gNB or TAP) that provides the one or more radio cells. This network node may be the same or different than the network node that provides the first cell. The user device receives the one or more second wake-up signals. The one or more radio cells may comprise at least a second radio cell (cell 2). The second cell may be a neighbor cell of the first cell. For example, the second cell may operate on FR2.

[0107] Herein 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.

[0108] In block 508, the user device determines whether to perform a cell re-selection procedure by comparing the received power or the received quality of the second wake-up signal(s) to the threshold. In this example, the user device determines to perform the cell re-selection procedure based at least on the comparison indicating that the received power or the received quality of the second wake-up signal(s) is above the threshold.

[0109] In block 509, in case the user device receives wake-up signals on a plurality of radio cells on the same frequency band, the user device may rank the plurality of radio cells based on received power or received quality of the wake-up signals, and select a radio cell from the plurality of radio cells based on the ranking.

[0110] For example, based on the WUS ranking parameters, the user device may determine that the second cell is the best ranked cell. For example, if the received power or the received quality of the WUS received on the second cell is higher than the received power or the received quality of the WUS received on other cell(s) of the same frequency band, then the user device may determine that the second cell is the best ranked cell.

[0111] In block 510, based on determining to perform the cell re-selection procedure and that the second cell is the best-ranked cell, the user device starts monitoring for an SSB on the second cell.

[0112] In block 511, the user device receives an SSB on the second cell.

The SSB may be transmitted by the network node (e.g., gNB or TRP) that provides the second cell.

[0113] In block 512, the user device determines whether the second cell is a suitable cell to camp on based on received power or received quality of the SSB on the second cell.

[0114] In block 513, the user device camps on the second cell based on determining that the second cell is a suitable cell to camp on.

[0115] FIG. 6 illustrates a flow chart according to an example embodiment of a method performed by an apparatus. For example, the apparatus may be, or comprise, or be comprised in, a user device. The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, or user equipment (UE). The user device may correspond to one of the user devices 100, 102 of FIG. 1 or the user device of FIG. 5.

[0116] In this example embodiment, the apparatus determines the frequency band for WUS monitoring based on the WUS frequency priorities. The apparatus scans the WUS of all candidate cells starting from the highest priority frequency (e.g., frequency band or frequency sub-band). If the apparatus does not receive any WUS in a given frequency band, the apparatus de-prioritizes this frequency band. The apparatus ranks the cells based on received WUS strength or quality. The apparatus selects the best-ranked cell based on the ranking of cells.

The apparatus measures the SSB of the best-ranked cell. Based on the SSB measurement the apparatus determines if the selected cell is suitable.

[0117] Referring to FIG. 6, in block 601, the apparatus receives information indicating at least a priority order of frequency bands to be monitored for wake-up signals.

[0118] In block 602, the apparatus selects a frequency band from the frequency bands based on the priority order. For example, the apparatus may select the highest priority frequency band according to the priority order.

[0119] In block 603, the apparatus monitors for wake-up signals on a plurality of radio cells of the selected frequency band. For example, the monitoring may start from the highest priority frequency band among the frequency bands according to the priority order.

[0120] In block 604, the apparatus receives the wake-up signals on the plurality of radio cells based on the monitoring and compares received power or received quality of the wake-up signals to a threshold in order to determine whether to perform a cell re-selection procedure. The apparatus may measure the received power or the received quality based on the received wake-up signals. [0121] If the received power or the received quality of the wake-up signals is not above the first threshold (block 604: no), then the process may return to block 602, i.e., the apparatus selects another frequency band based on the priority order and continues the WUS monitoring on that frequency band. In other words, in this case, the apparatus may monitor for the wake-up signals on a different frequency band than the highest priority frequency band based on the priority order, when the apparatus fails to receive any wake-up signals on the highest priority frequency band. Thus, the wake-up signals may be received on the highest priority frequency band or on the different frequency band.

[0122] If no WUS is found on any of the cells in any of the monitored frequency bands, the apparatus may fall back to SSB-based cell re-selection.

[0123] In block 605, if the received power or the received quality of at least one wake-up signal of the wake-up signals is above the threshold (block 604: yes), the apparatus ranks the plurality of cells based on the received power or the received quality of the wake-up signals received by the apparatus.

[0124] In block 606, the apparatus selects a cell from the plurality of cells based on the ranking. For example, the apparatus may select the cell with the highest WUS received power or quality among the plurality of cells.

[0125] In block 607, the apparatus performs SSB monitoring at the selected cell and receives an SSB on the selected cell based on the monitoring. [0126] In block 608, the apparatus determines whether the selected cell is suitable to camp on. For example, if the received power or the received quality of the SSB received on the selected cell is above a threshold, then the apparatus may decode the system information of that cell in order to determine whether the cell is suitable for other terms.

[0127] In block 609, based on determining that the selected cell is suitable to camp on (block 608: yes), the apparatus camps on the selected cell. [0128] Alternatively, if the apparatus determines that the selected cell is not suitable (block 608: no), then the process may return to block 606, i.e., the apparatus may select another cell based on the ranking (with WUS received power/quality above the threshold) and monitor for an SSB on that cell in order to determine whether it is suitable to camp on. In case none of the ranked cells are determined to be suitable, then the apparatus may restart the cell re-selection procedure.

[0129] FIG. 7 illustrates a signaling diagram according to another example embodiment. In this example embodiment, the frequency priorities for WUS-based cell re-selection are adjusted with respect to the energy storage or harvesting capability of the user device. If the user device has enough energy, it may prioritize frequencies of gNBs. If the user device has low energy, it may prioritize the frequencies for relays/readers. After the detection of another energy state, the user device may keep its connection with its current serving cell until the WUS threshold condition is satisfied. Alternatively, after the change of energy state, the user device may directly measure strength or quality of a WUS on one or more cells (e.g., reader/FR1 cell/FR2 cell) WUS based on the frequency priority.

[0130] This example embodiment may enable triggering WUS-based efficient cell re-selection for example for energy harvesting devices (e.g., RedCap devices or passive loT devices).

[0131] Referring to FIG. 7, in block 701, the user device is camping on a first cell (cell 1). In other words, the first cell may be the serving cell of the user device. For example, the user device may be an energy-harvesting device such as a passive loT device.

[0132] In block 702, the user device receives information, for example system information, on the first cell, wherein the information indicates one or more WUS-specific cell re-selection parameters. The information may be transmitted by a network node (e.g., gNB or TRP) that provides the first cell.

[0133] For example, the one or more WUS-specific cell re-reselection parameters may comprise at least a WUS threshold for received power or received quality of a WUS on the first cell. Alternatively, the threshold may be pre-defined at the user device (e.g., defined in specifications or hard-coded to the user device).

[0134] In block 703, the user device receives a first wake-up signal on the first cell. The first wake-up signal may be transmitted by the network node (e.g., gNB or TRP) that provides the first cell.

[0135] In block 704, the user device determines an energy state of the user device, wherein the energy state indicates an amount of harvested or stored energy available or predicted to be available at the apparatus. As an alternative to the currently available amount of energy, the prediction of energy arrival in the future may be used to define an energy state (e.g., to reduce state switching or pingpong). For example, in case of solar energy, during daytime, energy arrival prediction may be higher compared to night-time. Based on the energy state, the user device determines a frequency band to be monitored.

[0136] As an example, the user device may have three different energy states based on the harvested or stored energy.

[0137] In a first energy state (sleep mode), i.e., if the amount of energy is lower than a first energy threshold, the user device may prioritize the frequency of readers or relays. The readers or relays may be located very close to the user device, and thus it may be easier (i.e., require less power) for the user device to communicate with the readers or relays compared to gNBs.

[0138] Herein a reader may refer to another user device with a passive loT reader capability. For example, the reader may receive data from multiple sensors connected to the reader. The reader may be a passive loT reader, a fixed passive loT reader, or a mobile passive loT reader. The passive loT reader is a user device with the capability of a receiver. The fixed passive loT reader may have fixed deployment for more dense areas. The mobile passive loT reader may have mobility for probabilistic deployment.

[0139] The user device may differentiate readers from cells (e.g., gNBs) after it decodes some system information from each or by the knowledge of the frequency band that the reader is deployed on.

[0140] In a second energy state (low energy state), i.e., if the amount of energy is equal to or higher than the first energy threshold but lower than a second energy threshold, the user device may prioritize FR1. In the second energy state, the user device may, for example, transmit or receive paging messages, short messages, and/or small data transmissions (SDT).

[0141] In a third energy state (high energy state), i.e., if the amount of energy is equal to or higher than the second energy threshold, the user device may prioritize FR2. In the third energy state, the user device may transmit and receive high amounts of data (e.g., compared to the first and second energy states).

[0142] In block 705, a second wake-up signal is transmitted to the user device via the first cell. The second wake-up signal may be transmitted by the network node (e.g., gNB or TRP) that provides the first cell. The user device receives the second wake-up signal. For example, the first cell may operate on FR1. [0143] In block 706, the user device determines whether to perform a cell re-selection procedure by comparing the received power or the received quality of the second wake-up signal to the WUS threshold. In this example, the received power or the received quality of the second wake-up signal is below the threshold, and thus the user device determines to perform the cell re-selection procedure.

[0144] In block 707, based on determining to perform the cell re-selection procedure, the user device monitors for wake-up signals on the frequency band determined based on the energy state in block 704. In other words, the user device monitors, when the received power or the received quality of the second wake-up signal is below or equal to the WUS threshold, radio cells of the frequency band determined in block 704.

[0145] For example, if the user device determined that it is in the first energy state (sleep mode), the user device may monitor for wake-up signals from readers or relays. The reader or relay may operate as a base station with limited capability from the perspective of the user device. In this example, the user device receives a third wake-up signal from at least one reader or relay.

[0146] In case the user device receives wake-up signals on a plurality of radio cells of the determined frequency band, the user device may rank the plurality of radio cells based on received power or received quality of the wake-up signals, and select a radio cell from the plurality of radio cells based on the ranking.

[0147] In block 708, the user device determines whether the reader or relay is suitable to camp on. For example, if the received power or the received quality of an SSB received from the reader or relay is above a threshold, then the user device may decode the system information of that reader or relay in order to determine whether it is suitable to camp on.

[0148] In block 709, the user device camps on the reader or relay based on determining that it is suitable to camp on.

[0149] In blocks 710 and 711, the user device receives one or more wake-up signals (e.g., a fourth wake-up signal and a fifth wake-up signal) from the reader or relay.

[0150] For example, the user device may monitor multiple wake-up signals (e.g., the fourth wake-up signal and the fifth wake-up signal) over time to perform an estimation taking the average of the multiple signals.

[0151] In block 712, the user device may detect a change in the energy state, while camping on the reader or relay. Based on the change in the energy state, the user device determines a different frequency band to be monitored (compared to the one determined in block 704).

[0152] For example, the user device may harvest energy from the fourth wake-up signal and the fifth wake-up signal, and thus the user device may transition from the first energy state to the third energy state (high-energy state). Thus, the user device determines a corresponding cell re-selection priority, for

example for FR2.

[0153] In block 713, the reader or relay transmits a sixth wake-up signal to the user device. The user device receives the sixth wake-up signal.

[0154] In block 714, the user device determines whether to perform a cell re-selection procedure by comparing the received power or the received quality of the sixth wake-up signal to the threshold. In this example, the received power or the received quality of the sixth wake-up signal is below the threshold, and thus the user device determines to perform the cell re-selection procedure. [0155] In block 715, based on determining to perform the cell re-selection procedure (in block 714), the user device monitors for wake-up signals on the different frequency band (e.g., FR2) and receives a seventh wake-up signal on a second cell operating on the different frequency band (e.g., FR2). The seventh wake-up signal may be transmitted by a network node (e.g., gNB or TRP) that provides the second cell. This network node may be the same or different than the network node that provides the first cell.

[0156] In block 716, the user device determines whether the second cell is a suitable cell to camp on, for example based on received power or received quality of an SSB received on the second cell.

[0157] In block 717, the user device camps on the second cell of the different frequency band based on determining that the second cell is suitable to camp on.

[0158] The example explained by FIG. 7, 1) blocks 703 to 706,2] blocks 707 to 709, and 2) blocks 710 to 717 can also be performed independently from each other. FIG. 8 illustrates a flow chart according to an example embodiment of a method performed by an apparatus. For example, the apparatus may be, or comprise, or be comprised in, a user device. The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, a RedCap device, a passive IoT device, an energy harvesting device, or user equipment (UE). The user device may correspond to one of the user devices 100, 102 of FIG. 1 or the user device of FIG. 7.

[0159] In this example embodiment, the apparatus determines the WUS measurement based on the energy state. The apparatus scans the WUS of candidate cells based on the energy state. The apparatus ranks the cells based on the received WUS strength/quality. The apparatus determines the best-ranked cell based on the ranking of cells. The apparatus measures the SSB of the best-ranked cell in order to determine if the selected cell is suitable.

[0160] Referring to FIG. 8, in block 801, the apparatus receives a first wake-up signal on its serving cell and compares the received power or the received quality of the first wake-up signal to a threshold in order to determine whether to perform a cell re-selection procedure. In this case, the apparatus determines to perform the cell re-selection procedure based on the comparison indicating that the received power or the received quality of the first wake-up signal is below or equal to the threshold.

[0161] It should be noted that block 801 may be optional. For example, if the current serving cell is not managed by a reader, and if the apparatus is in a low energy state or sleep mode, it may switch from the current serving cell to the reader using the energy state change as the trigger (even if the WUS received power/quality of the serving cell is above the threshold).

[0162] In block 802, the apparatus determines an energy state of the apparatus, wherein the energy state indicates an amount of energy available or predicted to be available at the apparatus.

[0163] As an example, the apparatus may have three different energy states based on the harvested or stored energy.

[0164] In a first energy state (sleep mode), i.e., if the amount of energy is lower than a first energy threshold, the apparatus may prioritize the frequency of readers or relays. The readers or relays may be located very close to the apparatus, and thus it may be easier (i.e., require less power) for the apparatus to communicate with the readers or relays compared to gNBs.

[0165] In a second energy state (low energy state), i.e., if the amount of energy is equal to or higher than the first energy threshold but lower than a second energy threshold, the apparatus may prioritize FR1. In the second energy state, the apparatus may, for example, transmit or receive paging messages, short messages, and/or small data transmissions (SDT).

[0166] In a third energy state (high energy state), i.e., if the amount of energy is equal to or higher than the second energy threshold, the apparatus may prioritize FR2. In the third energy state, the apparatus may transmit and receive high amounts of data (e.g., compared to the first and second energy states).

[0167] In block 803, the apparatus determines, based on the energy state, a frequency band to be monitored for the cell re-selection procedure. [0168] In block 804, when the received power or the received quality of the first wake-up signal on the serving cell is equal to or below the threshold, the apparatus monitors for wake-up signals on a plurality of radio cells of the determined frequency band.

[0169] In block 805, the apparatus receives the wake-up signals on the plurality of radio cells based on the monitoring, and compares received power or received quality of the wake-up signals to the threshold. The apparatus may measure the received power or the received quality based on the received wake-up signals.

[0170] If the received power or the received quality of the wake-up signals is not above the first threshold (block 805: no), then the process may return to block 804, i.e., the apparatus may continue the WUS monitoring on the frequency band. If no WUS is detected on the frequency band within a certain amount of time, the apparatus may fall back to SSB-based cell re-selection.

[0171] It should be noted that block 805 may be optional. As an alternative, the process may proceed directly to block 806 from block 804.

[0172] In block 806, if the received power or the received quality of at least one wake-up signal of the wake-up signals is above the threshold (in case, block 805: yes), the apparatus ranks the plurality of cells based on the received power or the received quality of the wake-up signals received by the apparatus.

[0173] In block 807, the apparatus selects a cell from the plurality of cells based on the ranking. For example, the apparatus may select the cell with the highest WUS received power or quality among the plurality of cells.

[0174] In block 808, the apparatus performs SSB monitoring at the selected cell and receives an SSB on the selected cell based on the SSB monitoring.

[0175] In block 809, the apparatus determines whether the selected cell is suitable to camp on based on the SSB and system information received on the selected cell. For example, if the received power or the received quality of the SSB received on the selected cell is above a threshold, then the apparatus may decode the system information of the selected cell in order to determine whether it is suitable to camp on. For determining whether the selected cell is suitable, the apparatus may also determine whether the selected cell is a reader or not. For example, in the low energy state or sleep mode, the selected cell may be suitable, if it is a reader.

[0176] In block 810, based on determining that the selected cell is suitable to camp on (block 809: yes), the apparatus camps on the selected cell. [0177] Alternatively, if the apparatus determines that the selected cell is not suitable (block 809: no), then the process may return to block 807, i.e., the apparatus may select another cell based on the ranking (with WUS received power/quality above the threshold) and monitor for an SSB on that cell in order to determine whether it is suitable to camp on. In case none of the ranked cells are determined to be suitable, then the apparatus may restart the cell re-selection procedure.

[0178] FIG. 9 illustrates a flow chart according to an example embodiment of a method performed by an apparatus. For example, the apparatus may be, or comprise, or be comprised in, a user device. The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, or user equipment (UE). The user device may correspond to one of the user devices 100, 102 of FIG. 1, or the user device of any of FIGS. 3,5 or 7.

[0179] Referring to FIG. 9, in block 901, the apparatus receives a wake-up signal.

[0180] In block 902, the apparatus compares received power or received quality of the wake-up signal to a threshold.

[0181] In block 903, the apparatus determines whether to perform a cell re-selection procedure based at least on the comparison.

[0182] FIG. 10 illustrates a flow chart according to an example embodiment of a method performed by an apparatus. For example, the apparatus may be, or comprise, or be comprised in, a network node of a radio access network. The network node may correspond to the access node 104 of FIG. 1, or cell 1 of any of FIGS. 3,5 or 7.

[0183] Referring to FIG. 10, in block 1001, the apparatus transmits information indicating at least a threshold for comparing received power or received quality of a wake-up signal to and performing a cell re-selection procedure based at least on the comparison. The comparison and the cell re-selection procedure may be performed at another apparatus, for example at a user device, based on the threshold.

[0184] The blocks, related functions, and information exchanges (messages) described above by means of FIGS. 3-10 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.

[0185] As used herein, "at least one of the following: <a list of two or more elements>" and "at least one of <a list of two or more elements>" and similar wording, where the list of two or more elements are joined by "and" or "or", mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0186] FIG. 11 illustrates an example of an apparatus 1100 comprising means for performing one or more of the example embodiments described above. For example, the apparatus 1100 may be an apparatus such as, or comprising or comprised in, a user device. The user device may correspond to one of the user devices 100, 102 of FIG. 1, or the user device of any of FIGS. 3, 5 or 7. The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, or user equipment (UE).

[0187] The apparatus 1100 may comprise a circuitry or a chipset applicable for realizing one or more of the example embodiments described above. For example, the apparatus 1100 may comprise at least one processor 1110. The at least one processor 1110 interprets instructions (e.g., computer program instructions) and processes data. The at least one processor 1110 may comprise one or more programmable processors. The at least one processor 1110 may comprise programmable hardware with embedded firmware and may, alternatively or additionally, comprise one or more application-specific integrated circuits (ASICs).

[0188] The at least one processor 1110 is coupled to at least one memory 1120. The at least one processor is configured to read and write data to and from the at least one memory 1120. The at least one memory 1120 may comprise one or more memory units. The memory units may be volatile or nonvolatile. 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 1120 stores computer readable instructions that are executed by the at least one processor 1110 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 1110 executes the instructions using volatile memory for temporary storage of data and/or instructions. The computer readable instructions may refer to computer program code.

[0189] The computer readable instructions may have been pre-stored to the at least one memory 1120 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 1110 causes the apparatus 1100 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.

[0190] 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).

[0191] The apparatus 1100 may further comprise, or be connected to, an input unit 1130. The input unit 1130 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 1130 may comprise an interface to which external devices may connect to.

[0192] The apparatus 1100 may also comprise an output unit 1140. 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 1140 may further comprise one or more audio outputs. The one or more audio outputs may be for example loudspeakers.

[0193] The apparatus 1100 further comprises a connectivity unit 1150.

The connectivity unit 1150 enables wireless connectivity to one or more external devices. The connectivity unit 1150 may comprise at least one transmitter and at least one receiver 1151 that may be integrated to the apparatus 1100 or that the apparatus 1100 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 1150 may further comprise a wake-up receiver (WURx) 1152 for monitoring wake-up signals. The connectivity unit 1150 may comprise an integrated circuit or a set of integrated circuits that provide the wireless communication capability for the apparatus 1100. Alternatively, the wireless connectivity may be a hardwired application-specific integrated circuit (ASIC). The connectivity unit 1150 may comprise one or more components, such as: power amplifier, digital front end (DEE), 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.

[0194] It is to be noted that the apparatus 1100 may further comprise 30 various components not illustrated in FIG. 11. The various components may be hardware components and/or software components.

[0195] FIG. 12 illustrates an example of an apparatus 1200 comprising means for performing one or more of the example embodiments described above. For example, the apparatus 1200 may be an apparatus such as, or comprising, or comprised in, a network node of a radio access network. The network node may correspond to the access node 104 of FIG. 1, or cell 1 of any of FIGS. 3, 5 or 7. The network node may also be referred to, for example, as a network element, a radio access network (RAN) node, a next generation radio access network (NG-RAN) node, a NodeB, an eNB, a gNB, a base transceiver station (BTS), a base station, an NR base station, a 5G base station, an access node, an access point (AP), a relay node, a repeater, an integrated access and backhaul (IAB) node, an IAB donor node, a distributed unit (DU), a central unit (CU), a baseband unit (BBU), a radio unit (RU), a radio head, a remote radio head (RRH), or a transmission and reception point (TRP).

[0196] The apparatus 1200 may comprise, for example, a circuitry or a chipset applicable for realizing one or more of the example embodiments described above. The apparatus 1200 may be an electronic device comprising one or more electronic circuitries. The apparatus 1200 may comprise a communication control circuitry 1210 such as at least one processor, and at least one memory 1220 storing instructions 1222 which, when executed by the at least one processor, cause the apparatus 1200 to carry out one or more of the example embodiments described above. Such instructions 1222 may, for example, include a computer program code (software), wherein the at least one memory and the computer program code (software) are configured, with the at least one processor, to cause the apparatus 1200 to carry out one or more of the example embodiments described above. 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.

[0197] The processor is coupled to the memory 1220. The processor is configured to read and write data to and from the memory 1220. The memory 1220 30 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 1220 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.

[0198] The computer readable instructions may have been pre-stored to the memory 1220 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 1200 to perform one or more of the functionalities described above.

[0199] The memory 1220 may be implemented using any suitable data storage technology, such as semiconductor-based 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. For example, the configuration database may store a current neighbour cell list, and, in some example embodiments, structures of the frames used in the detected neighbour cells.

[0200] The apparatus 1200 may further comprise a communication 30 interface 1230 comprising hardware and/or software for realizing communication connectivity according to one or more communication protocols. The communication interface 1230 comprises at least one transmitter (Tx) and at least one receiver (Rx) that may be integrated to the apparatus 1200 or that the apparatus 1200 may be connected to. The communication interface 1230 may provide means for performing some of the blocks for one or more example embodiments described above. The communication interface 1230 may comprise one or more components, such as: power amplifier, digital front end (DFE), analogto-digital converter (ADC), digital-to-analog converter (DAC), frequency converter, (de)modulator, and/or encoder/decoder circuitries, controlled by the corresponding controlling units.

[0201] The communication interface 1230 provides the apparatus with radio communication capabilities to communicate in the cellular communication system. The communication interface may, for example, provide a radio interface to one or more user devices. The apparatus 1200 may further comprise another interface towards a core network such as the network coordinator apparatus or AMF, and/or to the access nodes of the cellular communication system.

[0202] The apparatus 1200 may further comprise a scheduler 1240 that is configured to allocate radio resources. The scheduler 1240 may be configured along with the communication control circuitry 1210 or it may be separately configured.

[0203] It is to be noted that the apparatus 1200 may further comprise various components not illustrated in FIG. 12. The various components may be hardware components and/or software components.

[0204] 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.

[0205] 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.

[0206] 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 in a 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.

[0207] It will be obvious to a person skilled in the art that, as technology advances, the inventive concept may be implemented in various ways. 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 example embodiments.

Claims

Claims 1. An apparatus comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive a wake-up signal; compare received power or received quality of the wake-up signal to a threshold; and determine whether to perform a cell re-selection procedure based at least on the comparison.
2. The apparatus according to claim 1, further being caused to: receive information indicating at least the threshold.
3. The apparatus according to any preceding claim, wherein the cell re-selection procedure comprises at least monitoring a synchronization signal block on one or more radio cells.
4. The apparatus according to any preceding claim, wherein the wake-up signal is received on a serving cell of the apparatus, and the cell re-selection procedure is performed based at least on the comparison indicating that the received power or the received quality of the wake-up signal is below or equal to the threshold.
5. The apparatus according to claim 4, further being caused to: monitor for the wake-up signal based on determining that the apparatus is located at a center area of the serving cell, or based on received power or received quality of one or more synchronization signal blocks received on the serving cell.
6. The apparatus according to any of claims 1-3, further being caused to: receive information indicating at least a priority order of frequency bands for monitoring wake-up signals including the wake-up signal; monitor for the wake-up signals on a plurality of radio cells by starting from a highest priority frequency band among the frequency bands according to the priority order; receive the wake-up signals on the plurality of radio cells based on the monitoring; rank the plurality of radio cells based on received power or received quality of the wake-up signals; select a radio cell from the plurality of radio cells based on the ranking; and camp on the selected radio cell based on determining that the selected radio cell is suitable to camp on.
7. The apparatus according to claim 6, wherein the wake-up signals are received on the highest priority frequency band.
8. The apparatus according to claim 6, further being caused to: monitor for the wake-up signals on a different frequency band than the highest priority frequency band based on the priority order when the apparatus fails to receive any wake-up signals on the highest priority frequency band.
9. The apparatus according to any of claims 1-5, further being caused to: determine an energy state of the apparatus, wherein the energy state indicates an amount of energy available or predicted to be available at the apparatus; determine, based on the energy state, a frequency band to be monitored; monitor, when the received power or the received quality of the wake-up signal is below or equal to the threshold, a plurality of radio cells of the frequency band; and receive wake-up signals on the plurality of radio cells based on the monitoring on the frequency band; select a radio cell from the plurality of radio cells; and camp on the selected radio cell based on determining that the selected radio cell is suitable to camp on.
10. The apparatus according to claim 9, further being caused to: rank the plurality of radio cells based on received power or received quality of the wake-up signals, wherein the radio cell is selected from the plurality of radio cells based on the ranking.
11. The apparatus according to any of claims 9-10, further being caused to: detect a change in the energy state, while camping on the radio cell; determine, based on the change in the energy state, a different frequency band to be monitored; receive a wake-up signal on a radio cell of the different frequency band by monitoring the different frequency band; and camp on the radio cell of the different frequency band based on determining that the radio cell of the different frequency band is suitable to camp on.
12. An apparatus comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: transmit information indicating at least a threshold for comparing received power or received quality of a wake-up signal to and performing a cell re-selection procedure based at least on the comparison.
13. The apparatus according to claim 12, wherein the information further indicates at least a priority order of frequency bands for monitoring the wake-up signal.
14. A method comprising: receiving a wake-up signal; comparing received power or received quality of the wake-up signal to a threshold; and determining whether to perform a cell re-selection procedure based at least on the comparison.
15. A method comprising: transmitting information indicating at least a threshold for comparing received power or received quality of a wake-up signal to and performing a cell re-selection procedure based at least on the comparison.
16. A non-transitory computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a wake-up signal; comparing received power or received quality of the wake-up signal to a threshold; and determining whether to perform a cell re-selection procedure based at least on the comparison.
17. A non-transitory computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: transmitting information indicating at least a threshold for comparing received power or received quality of a wake-up signal to and performing a cell re-selection procedure based at least on the comparison.