A wireless communication device, a network node and methods for 6g wake-up receiver operation in RRC idle state

Abstract

A method, performed by a wireless communications device, for receiving an upcoming message from a wireless communications network. The wireless communications device comprises one or more Radio Frequency, RF, receivers and is adapted to operate in a first power mode and a second power mode. A first power consumption of the one or more RF receivers in the first power mode is lower than a second power consumption of the one or more RF receivers in the second power mode. The method comprises, in the first power mode, receiving (801), using the one or more RF receivers, a Wake-Up Signal, WUS. The method further comprises, obtaining (802) scheduling information of the upcoming message. The scheduling information is indicated by the WUS. The method further comprises receiving (805), in the second power mode, the upcoming message using the one or more RF receivers (1110, 1120) based on the scheduling information.

Description

[0001] A WIRELESS COMMUNICATION DEVICE, A NETWORK NODE AND METHODS FOR 6G WAKE-UP RECEIVER OPERATION IN RRC IDLE STATE

[0002] TECHNICAL FIELD

[0003] The embodiments disclosed herein relate to wireless communications devices, a network node and methods for determining an application-specific energy-related resource usage. A corresponding computer program and a computer program carrier are also disclosed.

[0004] BACKGROUND

[0005] In a typical wireless communication network, wireless devices, also known as wireless communication devices, mobile stations, stations (ST A) and / or User Equipments (UE), communicate via a Local Area Network such as a Wi-Fi network or a Radio Access Network (RAN) to one or more core networks (CN). The RAN covers a geographical area which is divided into service areas or cell areas, which may also be referred to as a beam or a beam group, with each service area or cell area being served by a radio access node such as a radio access node, e.g., a Wi-Fi access point or a radio base station (RBS), which in some networks may also be denoted, for example, a NodeB, eNodeB (eNB), or gNB as denoted in 5G. A service area or cell area is a geographical area where radio coverage is provided by the radio access node. The radio access node communicates over an air interface operating on radio frequencies with the wireless device within range of the radio access node.

[0006] Specifications for the Evolved Packet System (EPS), also called a Fourth Generation (4G) network, have been completed within the 3rd Generation Partnership Project (3GPP) and this work continues in the coming 3GPP releases. A Fifth Generation (5G) network also referred to as 5G New Radio (NR) has also been specified and work is now directed to further specifications of the 5G network. This work will continue in the coming 3GPP releases. The EPS comprises the Evolved Universal Terrestrial Radio Access Network (E-UTRAN), also known as the Long Term Evolution (LTE) radio access network, and the Evolved Packet Core (EPC), also known as System Architecture Evolution (SAE) core network. E-UTRAN / LTE is a variant of a 3GPP radio access network wherein the radio access nodes are directly connected to the EPC core network rather than to Radio Network Controllers (RNCs) used in 3G networks. In general, in E-UTRAN / LTE the functions of a 3G RNC are distributed between the radio access nodes, e.g. eNodeBs in LTE, and the core network. As such, the RAN of an EPS has an essentially “flat” architecture comprising radio access nodes connected directly to one or more core networks, i.e. they are not connected to RNCs. To compensate forthat, the E-UTRAN specification defines a direct interface between the radio access nodes, this interface being denoted the X2 interface.

[0007] Wireless communication systems in 3GPP

[0008] Figure 1 illustrates a simplified wireless communication system. Consider the simplified wireless communication system in Figure 1, with a UE 12, which communicates with one or multiple access nodes 103-104, which in turn is connected to a network node 106. The access nodes 103-104 are part of the radio access network 10.

[0009] For wireless communication systems pursuant to 3GPP Evolved Packet System, (EPS), also referred to as Long Term Evolution, LTE, or 4G, standard specifications, such as specified in 3GPP TS 36.300 and related specifications, the access nodes 103-104 correspond typically to Evolved NodeBs (eNBs) and the network node 106 corresponds typically to either a Mobility Management Entity (MME) and / or a Serving Gateway (SGW). The eNB is part of the radio access network 10, which in this case is the E-UTRAN (Evolved Universal Terrestrial Radio Access Network), while the MME and SGW are both part of the EPC (Evolved Packet Core network). The eNBs are inter-connected via the X2 interface, and connected to EPC via the S1 interface, more specifically via S1-C to the MME and S1-U to the SGW.

[0010] For wireless communication systems pursuant to 3GPP 5G System, 5GS (also referred to as New Radio, NR, or 5G) standard specifications, such as specified in 3GPP TS 38.300 and related specifications, on the other hand, the access nodes 103-104 correspond typically to an 5G NodeB (gNB) and the network node 106 corresponds typically to either a Access and Mobility Management Function (AMF) and / or a User Plane Function (UPF). The gNB is part of the radio access network 10, which in this case is the NG-RAN (Next Generation Radio Access Network), while the AMF and UPF are both part of the 5G Core Network (5GC). The gNBs are inter-connected via the Xn interface, and connected to 5GC via the NG interface, more specifically via NG-C to the AMF and NG-U to the UPF.

[0011] To support fast mobility between NR and LTE and avoid change of core network, LTE eNBs may also be connected to the 5G-CN via NG-U / NG-C and support the Xn interface. An eNB connected to 5GC is called a next generation eNB (ng-eNB) and isconsidered part of the NG-RAN. LTE connected to 5GC will not be discussed further in this document; however, it should be noted that most of the solutions / features described for LTE and NR in this document also apply to LTE connected to 5GC. In this document, when the term LTE is used without further specification it refers to LTE-EPC.

[0012] Since UEs spend most of their time in RRC Idle state when there are no data transmissions it is important to have a low energy consumption of the UE when in RRC Idle state to ensure long battery life of the UE. Discontinuous reception (DRX), which allows the UE to conserve energy, is a crucial feature to achieve this and is natively supported in 3G, 4G, and in 5G. Both 4G and 5G also support extended DRX (eDRX) cycles of up to three hours to reduce the energy consumption of the UE even further, at the expense of increased downlink latency.

[0013] Rel-15 / 16 WUS

[0014] In Rel-15, a Wake-Up Signal (WUS) was specified for LTE, more specifically for NarrowBand Internet of Things (NB-loT) and LTE Machine type communications (LTE-M). The main motivation was reduction of UE energy consumption since with the NB-loT and LTE-M coverage enhancement Physical Downlink Control Channel (PDCCH) may be repeated many times and the WUS is relatively much shorter and hence requires less reception time for the UE. The logic is that a UE may check for a WUS a certain time before its Paging Occasion (PO), and only if a WUS is detected the UE would continue to check for PDCCH in the PO. If the UE doesn’t detect the WUS, which is most of the time, the UE may go back to a sleep state, in which the radio equipment is partly or completely turned off, to conserve energy. Due to the coverage enhancements the WUS may be of variable length depending on the UE’s coverage, see Figure 2 which Illustrates a WUS for NB-loT and LTE-M..

[0015] The lower sleep state the Main Receiver (MR) is put in, the longer time it will take to start up the MR upon WUS detection. Therefore, a longer WUS-PDCCH time offset is required for deeper MR sleep states as illustrated in Figure 3, which illustrates the use of eDRX and DRX WUS gaps for NB-loT and LTE-M (for Rel-15 LTE WUS the time offset is artificially tied to the use of eDRX).

[0016] In the Rel-16, the WUS feature was extended to also include UE sub-grouping, such that the number of UEs that are triggered by a WUS is further narrowed down to a smaller subset of the UEs that are associated with a specific PO.The purpose is to reduce the false paging rate, i.e. avoid that a given UE is unnecessarily woken up by a WUS transmission intended for another UE. This feature is referred to as Rel-16 group WUS, or GWUS. However, this is not directly related to Wake-Up Receivers (WUR) and will not further be explained here.

[0017] Rel-17 NR PEI

[0018] In Rel-17 ‘Paging Early Indication’ (PEI) was introduced for NR. Compared to the LTE WUS, it may be said that the PEI is a PDCCH-based wake-up signal (DCI format 2_7). Since no coverage enhancement was specified for NR (on a level comparable to NB-loT and LTE-M), the main gain for Rel-17 PEI was for scenarios where the small fraction of UEs are in bad coverage and with large synchronization error due to the use of longer DRX cycles. The gain for such UEs were that with the use of PEI they would typically only have to acquire one SSB before decoding PEI, instead of up to 3 SSBs for Physical Downlink Shared Channel (PDSCH) decoding of the PO if PEI is not used.

[0019] Rel-17 PEI will also support UE grouping for false paging reduction, similar to the Rel-16 GWUS above, which will have some gains at higher paging load.

[0020] NR WUR

[0021] In Rel-18, a WUR feature was studied for NR. The output of the Rel-18 study item on “low-power wake-up signal and receiver for NR” is collected in technical report 3gpp TR 38.869. In Rel-19 normative work is being carried out to support the feature.

[0022] Compared to LTE WUS and NR PEI the main intention is to have a low-power WUR to detect if there is incoming data for the UE, allowing the MR to reside in a sleep state to conserve more energy. That is, if the UE is paged in every paging occasion (PO) there is no gain compared to the legacy procedure (there is actually a drawback with WUS, PEI and WUR from the additional signal that must be transmitted and received) since in practice there is most often nothing being transmitted to the UE, but the UE still need to monitor frequently to ensure a short downlink latency for the very few occasions when there is.

[0023] In a Rel-18 study, both On-Off Keying (OOK) modulated WUS and Orthogonal Frequency-Division Multiplexing (OFDM) modulated WUS were promising solutions, and due to the inability to down-select to a single solution, a combined WUS is being introduced in Rel-19 as a political compromise. The Rel-19 Wl objective on the Low-Power WUS (LP-WUS) design refers to a “harmonized” WUS design which allows theWUS to be decoded by either an envelope detection based (e.g. OOK) WUR, or an OFDM-based WUR. Figure 4 illustrates a unified LP-WUS design. This may be done by specifying an OOK (OOK-1 and / or OOK-4) based LP-WUS with overlaid OFDM sequence(s) over the OOK symbol.

[0024] With this solution, the gNB will always transmit a harmonized LP-WUS signal, where the On-periods for the OOK modulation means OFDM subcarriers are being transmitted and the Off-periods means nothing is being transmitted, but the LP-WUS signal may either be received by an OOK-based WUR or an OFDM-based WUR. In general, a UE may either implement one WUR type or both.

[0025] The OOK-based WUR may have a somewhat lower energy consumption, but the OFDM-based WUR will have better link performance and coverage. Figure 5 illustrates different coverages for OOK-based WUR and OFDM-based WUR reception of the unified LP-WUS.

[0026] The OFDM-based WUS is also more efficient than the OOK-based WUS, allowing for e.g., a) a larger WUS payload, b) more redundancy bits for improved decoding performance, c) multiple WUS monitoring occasions for OFDM -based WUS during one WUS monitoring occasion for OOK-based WUS, etc. Figure 6 Illustrates unified LP-WUS content.

[0027] Overall, the OOK-based WUR may operate with a somewhat lower power considering one symbol or slot of reception, but the OFDM-based WUR has better link performance which leads to a shorter reception time and therefore lower energy consumption, especially in more challenging coverage. Moreover, the OFDM-based WUR is capable of receiving legacy Primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS) for synchronization and Radio Resource Management (RRM) mobility measurements, whereas to support OOK-based WUR UEs the network must broadcast a new OOK modulated low-power sync-signal (LP-SS).

[0028] SUMMARY

[0029] No 6G UE power saving feature for Idle state has been introduced and there may be benefits to introduce functionality on top of the 4G and 5G solutions.

[0030] Rel-15 / 16 LTE WUS, Rel-17 PEI and Rel-19 WUR operation all require the transmission of an additional signal from gNB apart from the WUS and the paging message. For the NW, this increases the signalling overhead and NW energy consumption. For the UE, this is an additional signal to detect and decode which increase the UE energy consumption and the latency.Some embodiments herein are directed to an Idle RRC state solution, e.g. with an OFDM-based WUS directly scheduling a paging message on PDSCH (e.g. using preconfigured formats), omitting PDCCH as a middle-step. Using pre-configured formats may comprise using a limited range of transport block sizes (covering reasonable paging messages sizes) and modulation and coding schemes (covering a reasonable range of cell sizes and conditions. Note that paging may need to be dimensioned for the cell-edge since it is broadcast).

[0031] Using the OFDM-based WUS enables the UEs to reduce energy consumption by monitoring the WUS signal with an OFDM-based WUR such that the main receiver may be kept in a sleep state. The OFDM-based solution covers both an OFDM-based WUS with encoded payload and a sequence-based OFDM-WUS. The sequence-based OFDM-WUS may comprise a sequence from a list of sequences, embedding an index as its order in the list, e.g. like the PSS field in the SSB. The OFDM-based WUS with encoded payload may be constructed like a Physical Broadcast CHannel (PBCH) field. Both the encoded payload OFDM-based WUS and the sequence-based OFDM-based WUS may carry both UE subgrouping information and PDSCH scheduling information.

[0032] An object of embodiments herein may be to obviate some of the problems related to the UE obtaining messages from the wireless communications network when the UE is in RRC idle or inactive state.

[0033] According to a first aspect, the object is achieved by a method, performed by a wireless communications device in a wireless communications network, for receiving an upcoming message from the wireless communications network. The wireless communications device comprises one or more Radio Frequency, RF, receivers and is adapted to operate in a first power mode and a second power mode. A first power consumption of the one or more RF receivers in the first power mode is lower than a second power consumption of the one or more RF receivers in the second power mode.

[0034] The method comprises, in the first power mode, receiving, using the one or more RF receivers, a Wake-Up Signal, WUS, from a radio access node of the wireless communications network.

[0035] The method further comprises, obtaining scheduling information of the upcoming message. The scheduling information is indicated by the WUS.

[0036] The method further comprises, in response to obtaining the scheduling information, activating the second power mode.The method further comprises receiving, in the second power mode, the upcoming message using the one or more RF receivers based on the scheduling information.

[0037] According to a second aspect, the object is achieved by a wireless communications device configured to perform the method according to the first aspect.

[0038] According to a third aspect, the object is achieved by a method, performed by a radio access node in a wireless communications network, for scheduling an upcoming message from the wireless communications network to a wireless communications device.

[0039] The method comprises transmitting a WUS indicating scheduling information about the upcoming message to the wireless communications device.

[0040] The method further comprises transmitting the upcoming message to the wireless communications device based on the scheduling information.

[0041] According to a fourth aspect, the object is achieved by a radio access node configured to perform the method according to the third aspect.

[0042] According to a further aspect, the object is achieved by a computer program comprising instructions, which when executed by a processor of the wireless communications device, causes the wireless communications device to perform actions according to the first aspect above.

[0043] According to a further aspect, the object is achieved by a computer program comprising instructions, which when executed by a processor of the radio access node, causes the radio access node to perform actions according to the third aspect above.

[0044] According to a further aspect, the object is achieved by a carrier comprising the computer program of the aspects above, wherein the carrier is one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or a computer-readable storage medium.

[0045] Since the wireless communications device obtains the scheduling information of the upcoming message indicated by the WUS the wireless communications device and the radio access node both save power since only one transmission from the radio access node is needed to both wake up the wireless communications device and indicate thescheduling information of the upcoming message. This also saves power of the wireless communications device since the wireless communications device can stay longer in the first, low-power, power mode compared to a solution where an intermediate message, such as a PDCCH message, indicates the scheduling information of the upcoming message.

[0046] Embodiments herein enable a baseline solution for UE power savings in 6G RRC Idle state which gives all the benefits of a WUR but removes the drawbacks and additional complexity from retro-fitting the WUR with an existing paging solution.

[0047] BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In the figures, features that appear in some embodiments are indicated by dashed lines.

[0049] The various aspects of embodiments disclosed herein, including particular features and advantages thereof, will be readily understood from the following detailed description and the accompanying drawings, in which:

[0050] Figure 1 is a block diagram schematically illustrating a simplified wireless communication system according to prior art,

[0051] Figure 2 is a block diagram schematically illustrating WUS for NB-loT and LTE-M according to prior art,

[0052] Figure 3 is a block diagram schematically illustrating a use of eDRX and DRX WUS gaps for NB-loT and LTE-M according to prior art,

[0053] Figure 4 is a block diagram schematically illustrating a unified LP-WUS design according to prior art,

[0054] Figure 5 is a block diagram schematically illustrating different coverage for OOK- based WUR and OFDM-based WUR reception of the unified LP-WUS, Figure 6 is a schematic illustration of unified LP-WUS content,

[0055] Figure 7 is a block diagram schematically illustrating a wireless communications network,

[0056] Figure 8a is a flow chart illustrating a method performed by a wireless communications device according to some embodiments disclosed herein, Figure 8b is a flow chart illustrating a method performed by a radio access node according to some embodiments disclosed herein,

[0057] Figure 9 is a block diagram schematically illustrating embodiments herein in which a WUS directly schedules a paging message on PDSCH,Figure 10 is a block diagram schematically illustrating embodiments herein in which one or more reference signals between a WUS occasion and a paging message on PDSCH are provided,

[0058] Figure 11 is a block diagram schematically illustrating a wireless communications device,

[0059] Figure 12 is a block diagram schematically illustrating a radio access node.

[0060] DETAILED DESCRIPTION

[0061] In the following, 5G / NR terminology is used to exemplify concepts of embodiments disclosed herein. However, these concepts apply to corresponding 6G concepts and frameworks, even if names of signals and channels will not be the same for 6G as for 5G.

[0062] Even though embodiments disclosed herein are exemplified with paging on PDSCH, the solution and the embodiments are equally applicable to broadcast / multi-cast transmissions wherein a WUR is used to wake up a main receiver (MR) for reception of certain data such as Broadcast / multicast transmission, system information reception and alike. For the sake of simplicity, only the paging use case is described. For example, a SIB- WUS may similarly include the scheduling info for the SIB-related PDSCH transmission, obviating the need for a scheduling DCI (PDCCH).

[0063] According to some embodiments herein UEs of future generations, such as 6G, should support WUR operation in RRC Idle state. The UEs may for example be mandated to support WUR operation in RRC Idle state. The WUR may be OFDM-based.

[0064] This may for example be achieved by powering off circuits and parts of the MR. In this way paging monitoring in RRC Idle may be reduced to two steps (WUS - paging message on PDSCH), compared to the three steps in 4G and 5G solutions, (WUS -paging message scheduling on PDCCH - paging message on PDSCH).

[0065] Embodiments herein relate to wireless communication networks in general. Figure 7 is a schematic overview depicting a wireless communications network 100 wherein embodiments herein may be implemented. The wireless communications network 100 comprises one or more RANs and one or more CNs. The wireless communications network 100 may use a number of different technologies, such as Wi-Fi, Long Term Evolution (LTE), LTE-Advanced, 5G, New Radio (NR), Wideband Code Division Multiple Access (WCDMA), Global System for Mobile communications / enhanced Data rate for GSM Evolution (GSM / EDGE), Worldwide Interoperability for Microwave Access (WiMax), or Ultra Mobile Broadband (UMB), just to mention a few possible implementations.Embodiments herein relate to recent technology trends that are of particular interest in a 5G context, however, embodiments are also applicable in further development of the existing wireless communication systems such as e.g. WCDMA and LTE and to future 6G wireless communication systems.

[0066] Network nodes operate in the wireless communications network 100. The network nodes may for example be access nodes such as a radio access node 111. The radio access node 111 provides radio coverage over a geographical area, a service area referred to as a cell 115, which may also be referred to as a beam or a beam group of a first radio access technology (RAT), such as 5G, LTE, Wi-Fi or similar. There may also be further cells, such as a second cell 116.

[0067] The radio access node 111 may be a NR-RAN node, transmission and reception point e.g. a base station, a radio access node such as a Wireless Local Area Network (WLAN) access point or an Access Point Station (AP STA), an access controller, a base station, e.g. a radio base station such as a NodeB, an evolved Node B (eNB, eNode B), a gNB, a base transceiver station, a radio remote unit, an Access Point Base Station, a base station router, a transmission arrangement of a radio base station, a stand-alone access point or any other network unit capable of communicating with a wireless device within the service area depending e.g. on the radio access technology and terminology used. The radio access node 111 may be referred to as a serving radio access node and communicates with a UE with Downlink (DL) transmissions to the UE and Uplink (UL) transmissions from the UE.

[0068] A number of wireless communications devices operate in the wireless communication network 100, such as a wireless communications device 121 and a second wireless communications device 122. The wireless communications devices 121 , 122 may each be a UE. The wireless communications devices 121 , 122 may further each be an FWA node, or nodes with similar functionality.

[0069] The wireless communications devices 121 , 122 may further each be a mobile station, a non-access point (non-AP) STA, a STA, a user equipment and / or a wireless terminals, that communicate via one or more Access Networks (AN), e.g. RAN, e.g. via the radio access node 111 to one or more core networks (CN) e.g. comprising a ON node 130, for example comprising an Access Management Function (AMF). It should be understood by the skilled in the art that “UE” is a non-limiting term which means any terminal, wireless communication terminal, user equipment, Machine TypeCommunication (MTC) device, Device to Device (D2D) terminal, or node e.g. smart phone, laptop, mobile phone, sensor, relay, mobile tablets or even a small base station communicating within a cell.

[0070] Methods herein may in a first aspect be performed by the wireless communications device 121 and in a second aspect by the radio access node 111. As an alternative, a Distributed Node (DN) and functionality, e.g. comprised in a cloud 140 as shown in Figure 7, may be used for performing or partly performing the methods.

[0071] Embodiments herein will now be described in more detail. Embodiments herein disclose methods performed by the wireless communications device 121 for receiving an upcoming message from the wireless communications network 100.

[0072] In some embodiments, OFDM-based WUS and WUR is used which has several advantages: 1) the WUS may carry information needed for paging message scheduling on PDSCH; 2) In the UEthe WUR may achieved by turning off components of the main receiver such that no additional hardware is required (or at least minimized), e.g. the WUR may be achieved by shutting down certain functionality of the main receiver, and running other functionalities in a less power hungry and more inaccurate mode; 3) UEs may using only WUR perform synchronization and RRM mobility measurements more efficiently using NR-like PSS / SSS, hence reducing the energy consumption for these frequent operations. This is possible since the OFMD-based WUR is capable of l / Q sampling, which is sufficient for SSS decoding. PSS / SSS is required to obtain downlink sync, and SSS is used by the UE for RRM mobility measurements in RRC Idle / lnactive. So a UE need only run the OFDM-based WUR to perform all Idle mode operations with a minimum of energy consumption.

[0073] In some other embodiments OOK-based WUS and WUR may be used. In yet some further embodiments Frequency-Shift Keying (FSK)-based WUS and WUR may be used.

[0074] Figure 8a is a flowchart and illustrates example methods, performed by the wireless communications device 121 in the wireless communications network 100, for receiving an upcoming message from the wireless communications network 100. The upcoming message may be a paging message. Most of the following embodiments will be described based on the assumption that the upcoming message is a paging message.The methods comprise one or more of the following actions, which actions may be taken in any suitable order.

[0075] The wireless communications device 121, which is illustrated in more detail in Figure 11, comprises one or more Radio Frequency (RF) receivers 1110, 1120. The one or more RF receivers 1110, 1120 may be for wireless communication of data or control signals or both within the wireless communications network 100.

[0076] The wireless communications device 121 is adapted to operate in a first power mode and a second power mode. A first power consumption of the one or more RF receivers 1110, 1120 in the first power mode is lower than a second power consumption of the one or more RF receivers 1110, 1120 in the second power mode. In some embodiments herein the first power consumption is less than one fifth of the second power consumption, preferably less than one tenth of the second power consumption.

[0077] The one or more RF receivers 1110, 1120 may comprise a first RF receiver 1110 for receiving the WUS and may comprise a second RF receiver 1120 for receiving the upcoming message. The second RF receiver 1120 may, when active, consume a higher power than the first RF receiver 1110 when active. In some embodiments herein the second RF receiver 1120 is a main receiver and the first RF receiver 1110 is a WUR.

[0078] Action 801:

[0079] The wireless communications device 121 in the first power mode, receives, using the one or more RF receivers 1110, 1120, a Wake-Up Signal, WUS, from the radio access node 111 of the wireless communications network 100. The wireless communications device 121 may receive the WUS when the wireless communications device 121 is in an idle or inactive Radio Resource Control, RRC, state. The WUS is sent on a physical channel other than the PDCCH.

[0080] In some embodiments wireless communications device 121 obtains further information, indicated by the received WUS, about at least one reference signal to be received in the first receiver mode before receiving the upcoming message. Thus, based on the reception of the WUS, such as an RRC Idle or inactive state WUS, the UE further is made aware of an availability of reference signals (e.g., SSBs or alike) being transmitted by the network after the WUS occasion as exemplified in Figure 10. These reference signals may then be used by the wireless communications device 121 for measurements or channel estimation or both before the PDSCH reception. The at leastone reference signal may be a synchronization signal or a Radio Resource Management, RRM, mobility measurement signal.

[0081] The timing of the reference signals may either be in relation to the WUS (e.g., offset after WUS) or in relation to the PDSCH (e.g., offset before PDSCH). In some embodiments herein, the timing offsets mentioned above are prespecified in a standard specification, or preconfigured e.g. as part of system information whereas in some other embodiments (as described below) the WUS may carry information about such offsets.

[0082] In some embodiments the at least one reference signal comprises a multiple of reference signals. Then the method may further comprise receiving less than all of the multiple of reference signals based on the obtained information about the at least one reference signal. In some embodiments, when multiple instances of reference signals are provided, the wireless communications device 121 only receives the instances necessary based on latest known coverage status. For example, a wireless communications device in good coverage may choose to only consume one reference signal instance (e.g., the one closest to) the PDSCH. Then the second RF receiver 1120, such as the main receiver, may also wake up later compared to a wireless communications device in poor coverage which would have to wake up earlier and consume more instances of the reference signals.

[0083] Thus, the wireless communications device 121 may further obtain a timing offset from the WUS to the at least one reference signal indicated by the received WUS.

[0084] The scheduling information of the upcoming message may be indicated by a payload of the WUS or by a resource allocation of the WUS or both.

[0085] In some embodiments disclosed herein, the Idle WUS for paging indication may carry a message or payload that depends on the WUS signal design or a resource allocation or both. For example, the payload may vary between e.g. 7-50 bits depending on the WUS design or the number of resource elements allocated to the WUS. More allocated resource elements may increase the size of the payload. Message components described below do not presume a specific message size, and a subset of the described components may be chosen to be transmitted in WUS. Note also that the WUS contents / message may be equally well mapped to a sequence index in a sequence modulation approach, or inserted as encoder input in a channel coded design. Thus, the payload of the OFDM modulated WUS may be based on sequence modulation, or may be an encoded payload. Thus, multiple WUS sequences may be defined for paging. EachWUS sequence may be configured (either hard-coded in a standard specification or in SI) to map to a certain format (Transport Block Size (TBS), Modulation and Coding Scheme (MCS), etc.) of the paging PDSCH.

[0086] In general, a UE may listen for several WUS sequences which corresponds to different scheduling of the paging message. See the following example:

[0087]

[0088] Table 1.

[0089] A given UE may then need to blindly decode all the WUS sequences corresponding to its ‘WUR UE subgroup’, e.g. subgroup 1 in Table 1 above, giving the gNB some flexibility for proper scheduling of the paging message on PDSCH.

[0090] The scheduling information of the upcoming message may comprises one or more of: an indication of a wireless communications device or a group of wireless devices for which the upcoming message is intended, time and / or frequency resources of the upcoming message, the timing offset from the WUS to the upcoming message, transport block size of the upcoming message, modulation and coding which the wireless communications device 121 should apply when decoding the upcoming message.

[0091] For example, the indication of the wireless communications device or the group of wireless devices for which the upcoming message is intended may be a UE group indication. UEs may monitor a certain T / F resource for WUS and a given WUS “trigger” may apply to only a subset of those UEs, which may be indicated via group ID.For example, the timing offset from the WUS to the upcoming message may be the time interval from receiving the WUS to the paging occasion location where the wireless communications device 121 may expect to find the paging message.

[0092] The offsets (offset to the upcoming message, such as the paging message, and offset to reference signals) and the characteristics of the reference signals may in some embodiments be preconfigured and provided to the wireless communications device 121 via dedicated or broadcast signaling. In some sub-embodiments, the network may configure different offsets and characteristics for different groups of wireless communications devices. For example, wireless communications devices of different capabilities (e.g. based on a wakeup time of the second RF receiver 1120, such as the main receiver) may be assigned to different paging occasions where for the different paging occasions different offsets and / reference signals may be applicable. For example, wireless communications devices with less capable receivers may be in need of more reference signals compared to other UEs and therefore these UEs are assigned to different paging occasions.

[0093] In some embodiments the WUS further indicates one or more of:

[0094] • A short message information or other information that do not require transmission of the upcoming message;

[0095] • Characteristics of the at least one reference signal.

[0096] The WUS may comprise a synchronisation signal. In one embodiment, the WUS may include an embedded sync component. The WUS message part may be preceded by a dedicated “loop convergence" component (e.g. one or more PSS-like sequences) to remove dependence on a recent SSB. The embedded sync component may be used for Automatic Gain Control, coarse and fine sync, etc.

[0097] Thus, in some embodiments the WUS message may comprise one or more of the following information components:

[0098] • Indication which UE or UE group(s) is targeted by the message (UE subgrouping) • Paging PDSCH scheduling information, such as time and frequency resources of the paging PDSCH or transport block size and modulation and coding which the UE should apply when decoding the PDSCH

[0099] Short message info and other contents that do not require the paging message transmission in legacy paging framework• Offset to paging PDSCH

[0100] • Offset to reference signals (e.g., SSBs or alike)

[0101] • Characteristics of the reference signals (e.g., number of SSBs, burst, reference signal type, etc.)

[0102] In some embodiments disclosed herein the WUS is an OFDM-modulated WUS. However, the WUS may also be an On Off Keying, OOK, -modulated WUS, or a Frequency Shift Keying, FSK, -modulated WUS ora combination of any of these.

[0103] The WUS may be received based on a pre-configured format.

[0104] Action 802:

[0105] The wireless communications device 121 obtains scheduling information of the upcoming message. The scheduling information is indicated by the received WUS.

[0106] Action 803:

[0107] In response to obtaining the scheduling information, the wireless communications device 121 activates the second power mode.

[0108] Action 804:

[0109] In some embodiments disclosed herein the wireless communications device 121 receives the at least one reference signal.

[0110] Action 805:

[0111] The wireless communications device 121 may receive, in the second power mode, the upcoming message using the one or more RF receivers 1110, 1120 based on the obtained scheduling information.

[0112] PDSCH scheduling

[0113] In legacy NR operation, the paging message on PDSCH is scheduled by PDCCH using DCI format 1_0 scrambled by P-RNTI containing the following fields:

[0114]

[0115]

[0116] Table 2.

[0117] However, having the flexibility to change these parameters for every paging transmission is not required in practice and in some embodiments disclosed herein a number of pre-defined scheduling formats are instead used. A number of pre-defined scheduling formats may be configured in system information (SI) and which format is applied may be indicated by the paging message PDSCH configuration index carried by the WUS. For example, using 2 bits in WUS, 4 different configurations for the parameters given in Table 2 above may be given in SI and the network may dynamically in WUS indicate to the UE which PDSCH scheduling is applied. (Hard-coded scheduling configurations in the standard specification is another option, but it has more limited flexibility).

[0118] Short messages and indications

[0119] In some embodiments herein, short messages, SI change notification, Public Warning System / Earthquake and Tsunami Warning System / Commercial Mobile Alert System messages, and other messages which may be indicated in the legacy paging procedure in 5G may be indicated in a common part of the paging message on PDSCH and does not have the be carried in the WUS. These events are rare in practice which motivates such a solution.

[0120] In another embodiment, bits indicating one or more short indications, e.g. an SI update indication, may be included as bit fields in the WUS message. Based on such indications, the wireless communications device 121 may then skip receiving the Paging PDSCH and directly goes for reception of SI or ETWS / CMAS messages.

[0121] Target UE subgroup indicationThe wireless communications device 121 may be configured with a WUS occasion / resource that it monitors, e.g. a time / frequency location. The WUS occasion (WO) allocation may be conceptually similar to a PO definition in NR, but details may differ.

[0122] The wireless communications devices monitoring a given WUS occasion may be further divided into two or more subgroups, e.g. N subgroups, to reduce false wake-up probability. The WUS message may contain a bit field indicating the WUS subgroup info.

[0123] In one embodiment, the subgroup information is provided in the form of a bitmap of length N, where each bit position corresponds to a subgroup index, and the state of the bit indicates whether the respective subgroup is targeted. This allows indicating all possible 2Ncombinations of the N subgroups in a length-N field.

[0124] In another embodiment, not all combinations may be represented, but e.g. all single subgroups and two-group combinations may be represented. A lookup table may be defined to map the field value to the targeted subgroup values. Then the subgroup indication field may be shorter than N bits, s

[0125] Example WUS message structure

[0126] In some embodiments below illustrate WUS message / bitstring structure to indicate which of three subgroups of wireless communications devices in the WUS monitoring occasions are being paged, and which out of two different pre-defined PDSCH scheduling formats are used. Assuming that a sequence-based OFDM WUS is used to carry the needed information, Table 3 below also gives an example of mapping 16 WUS sequences to the 16 messages / bitstrings. The radio access node 111 transmits one WUS sequence, and the wireless communications device 121 depending on which WUS sequence is received may determine the information in all of the other columns.

[0127]

[0128]

[0129] Table 3.

[0130] Note that using a bitstring is just an example and that the signalling bits may equally well be used to indicate separate UE subgroups, as in the example given below for two bits:

[0131]

[0132] Table 4.

[0133] Using two bits for subgrouping info, four different subgroups may be defined according to Table 4 (but here subgroup four corresponds to ‘all UEs'). Thus, each of the four states, or code points, of the 2-bit code in Table 4 may represent a predefined meaning. With a bitmap only two subgroups may be defined, one for the first bit and another for the second, but the benefit is that they may be paged simultaneously.

[0134] WUS configuration

[0135] In some embodiments, the wireless communications device 121 may be provided the WUS configuration when it is released to RRC idle / inactive mode. The configurationmay comprise one or more of the monitoring periods or patterns, other WUS occasion determination parameters (formula parameters or explicit offset values), frequency location of the WUS, WUS format (payload structure, etc. The configuration may be UE-or cell-specific).

[0136] In another embodiment, the wireless communications device 121 may obtain the WUS configuration for the cell via SI broadcast, e.g. in SIB1 or equivalent.

[0137] WUS signal design

[0138] As mentioned above, in some embodiments, the WUS may be based on sequence modulation, where a set of 2Nsequences is defined, each sequence corresponding to a length-N bit label which constitutes the payload. i.e. the WUS message.

[0139] In some embodiments, the sequence-based WUS bandwidth may be limited to 20-30 PRBs, corresponding to the SSB bandwidth, resulting in message length N=7-9 bits when using orthogonal sequences. In another embodiment, the WUS bandwidth may be extended to ~100 PRBs, corresponding to the PDCCH bandwidth range with Aggregation Level 16, supporting message length N=11-13 bits, Additional message bits may be accommodated, i.e. more sequences defined, if non-orthogonal sequences are used.

[0140] The WUS resources in an OFDM symbol may be segmented into multiple independently detectable bit labels that may be aggregated to create the full message, or multiple OFDM symbols may be similarly used together. This may allow e.g., doubling or quadrupling the message size to accommodate up to more than forty bits, at the cost of lower detection performance.

[0141] In some other embodiments, the WUS message may be delivered using encoded payload (as for the PDSCH). If DCI- or PBCH-like encoding is used, payload of ~30-50 bits may be supported.

[0142] Figure 8b illustrates example methods performed by the radio access node 111 in the wireless communications network 100, for scheduling the upcoming message from the wireless communications network 100 to the wireless communications device 121.’The method according to any of the claims 17-19, wherein transmitting 813 the WUS is performed when the wireless communications device 121 is in an idle or inactive Radio Resource Control, RRC, state.

[0143] The methods comprises one or more of the following actions, which actions may be taken in any suitable order.

[0144] Action 811:

[0145] The radio access node 111 transmits the WUS indicating scheduling information about the upcoming message to the wireless communications device 121.

[0146] Action 812:

[0147] In some embodiments disclosed herein the radio access node 111 transmits, based on further information indicated by the transmitted WUS, the at least one reference signal before transmitting the upcoming message.

[0148] The at least one reference signal may be the synchronization signal or the RRM mobility measurement signal.

[0149] Action 813:

[0150] The radio access node 111 transmits the upcoming message to the wireless communications device 121 based on the scheduling information indicated by the WUS.

[0151] Figure 9 illustrates embodiments herein in which the WUS directly schedules the paging message on PDSCH.

[0152] Figure 10 illustrates one or more reference signals between the WUS occasion and the paging message on PDSCH.

[0153] Figure 11 shows an example of the wireless communications device 121.

[0154] The wireless communications device 121 is adapted to communicate in the wireless communications network 100.

[0155] The wireless communications device 121 is further adapted to, in the first power mode, receive, using the one or more RF receivers 1110, 1120, the Wake-Up Signal, WUS, from the radio access node 111 of the wireless communications network 100.The wireless communications device 121 is further adapted to, obtain scheduling information of the upcoming message, wherein the scheduling information is indicated by the received WUS.

[0156] The wireless communications device 121 is further adapted to, in response to obtaining the scheduling information, activate the second power mode.

[0157] The wireless communications device 121 is further adapted to, receive, in the second power mode, the upcoming message using the one or more RF receivers 1110, 1120 based on the obtained scheduling information.

[0158] In some embodiments disclosed herein the wireless communications device 121 is further adapted to obtain further information, indicated by the received WUS, about the at least one reference signal to be received in the first receiver mode before receiving the upcoming message.

[0159] The wireless communications device 121 may be further adapted to obtain the timing offset from the WUS to the at least one reference signal indicated by the received WUS.

[0160] In some embodiments disclosed herein the wireless communications device 121 is further adapted to receive the WUS when the wireless communications device 121 is in an idle or inactive RRC state.

[0161] The wireless communications device 121 may be further adapted to receive the WUS based on the pre-configured format.

[0162] Figure 12 shows an example of the radio access node 111. The radio access node 111 is adapted to schedule the upcoming message from the wireless communications network 100 to the wireless communications device 121. The radio access node 111 is further adapted to transmit the WUS indicating scheduling information about the upcoming message to the wireless communications device 121.

[0163] The radio access node 111 is further adapted to transmit the upcoming message to the wireless communications device 121 based on the scheduling information.In some embodiments disclosed herein the radio access node 111 is further adapted to transmit, based on further information indicated by the transmitted WUS, the at least one reference signal before transmitting the upcoming message.

[0164] The radio access node 111 may be further adapted to transmit the WUS when the wireless communications device 121 is in an idle or inactive RRC state.

[0165] The wireless communications device 121 and the radio access node 111 may comprise a respective input and output interface, IF, 1106, 1206 configured to communicate with each other, see Figures 7-8. The input and output interface may comprise a receiver (not shown) and a transmitter (not shown).

[0166] The embodiments herein may be implemented through a respective processor or one or more processors, such as the respective processor 1104 and 1204, of a processing circuitry in the wireless communications device 121 and the radio access node 111 and depicted in Figures 7-8 together with computer program code for performing the functions and actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the embodiments herein when being loaded into the respective wireless communications device 121 and the radio access node 111. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server and downloaded to the respective wireless communications device 121 and radio access node 111.

[0167] The wireless communications device 121 and the radio access node 111 may further comprise a respective memory 1102 and 1202 comprising one or more memory units. The memory comprises instructions executable by the processor in the wireless communications device 121 and the radio access node 111.

[0168] Each respective memory 1102 and 1202 is arranged to be used to store e.g. information, data, configurations, and applications to perform the methods herein when being executed in the respective wireless communications device 121 and the radio access node 111.

[0169] In some embodiments, a respective computer program 1103 and 1203 comprises instructions, which when executed by the respective processor 1104, 1204, cause therespective wireless communications device 121 and network node 111 to perform the actions above.

[0170] In some embodiments, a respective carrier 1105 and 1205 comprises the respective computer program, wherein the carrier is one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, ora computer-readable storage medium.

[0171] Those skilled in the art will also appreciate that the units in the units described above may refer to a combination of analogue and digital circuits, and / or one or more processors configured with software and / or firmware, e.g. stored in the respective wireless communications device 121 and network node 111 described above. One or more of these processors, as well as the other digital hardware, may be included in a single Application-Specific Integrated Circuitry (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC).

[0172] When using the word "comprise" or “comprising” it shall be interpreted as nonlimiting, i.e. meaning "consist at least of'.

[0173] The embodiments herein are not limited to the above described preferred embodiments. Various alternatives, modifications and equivalents may be used.

Claims

CLAIMS1. A method, performed by a wireless communications device (121) in a wireless communications network (100), for receiving an upcoming message from the wireless communications network (100), the wireless communications device (121) comprising one or more Radio Frequency, RF, receivers (1110, 1120) and adapted to operate in a first power mode and a second power mode, and wherein a first power consumption of the one or more RF receivers (1110, 1120) in the first power mode is lower than a second power consumption of the one or more RF receivers (1110, 1120) in the second power mode, the method comprises:in the first power mode, receiving (801), using the one or more RF receivers (1110, 1120), a Wake-Up Signal, WUS, from a radio access node (111) of the wireless communications network (100);obtaining (802) scheduling information of the upcoming message, wherein the scheduling information is indicated by the received WUS;in response to obtaining the scheduling information, activating (803) the second power mode; andreceiving (805), in the second power mode, the upcoming message using the one or more RF receivers (1110, 1120) based on the obtained scheduling information.

2. The method according to claim 1 , further comprising obtaining further information, indicated by the received WUS, about at least one reference signal to be received in the first receiver mode before receiving the upcoming message.

3. The method according to claim 2, wherein the at least one reference signal is a synchronization signal or a Rado Resource Management, RRM, mobility measurement signal.

4. The method according to claim 2 or 3, wherein the at least one reference signal comprises a multiple of reference signals and wherein the method further comprises receiving less than all of the multiple of reference signals based on the obtained information about the at least one reference signal.

5. The method according to any of the claims 2-4, further comprising obtaining a timing offset from the WUS to the at least one reference signal indicated by the received WUS.

6. The method according to any of the claims 1-5, wherein the scheduling information of the upcoming message is indicated by a payload of the WUS or by a resource allocation of the WUS or both.

7. The method according to any of the claims 1-6, wherein receiving the WUS is performed when the wireless communications device (121) is in an idle or inactive Radio Resource Control, RRC, state.

8. The method according to any of the claims 1-7, wherein the scheduling information of the upcoming message comprises one or more of: an indication of a wireless communications device or a group of wireless devices for which the upcoming message is intended, time and / or frequency resources of the upcoming message, a timing offset from the WUS to the upcoming message, transport block size of the upcoming message, modulation and coding which the wireless communications device (121) should apply when decoding the upcoming message.

9. The method according to any of the claims 1-8, wherein the WUS further indicates, one or more of:• A short message information or other information that do not require transmission of the upcoming message;• Characteristics of the at least one reference signal.

10. The method according to any the claims 1-9, wherein the WUS comprises a synchronisation signal.

11. The method according to any the claims 1-10, wherein the WUS is an Orthogonal Frequency Division Multiplexing, OFDM, modulated WUS.

12. The method according to claim 11 in combination with claim 6, wherein the payload of the OFDM modulated WUS is based on sequence modulation, or is an encoded payload.

13. The method according to any the claims 1-12, wherein the WUS is received based on a pre-configured format.

14. The method according to any of the claims 1-13, wherein the one or more RF receivers (1110, 1120) comprises a first RF receiver (1110) for receiving the WUS and comprises a second RF receiver (1120) for receiving the upcoming message.

15. The method according to any of the claims 1-14, wherein the first power consumption is less than one fifth of the second power consumption, preferably less than one tenth of the second power consumption.

16. The method according to any of the claims 1-15, wherein the WUS is sent on a physical channel other than a Physical Downlink Control Channel, PDCCH.

17. The method according to any of the claims 1-16, wherein the upcoming message is a paging message.

18. A method, performed by a radio access node (111) in a wireless communications network (100), for scheduling an upcoming message from the wireless communications network (100) to a wireless communications device (121), the method comprises:transmitting (811) a WUS indicating scheduling information about the upcoming message to the wireless communications device (121); and transmitting (813) the upcoming message to the wireless communications device (121) based on the scheduling information.

19. The method according to claim 18, further comprising, transmitting (812) based on further information indicated by the transmitted WUS, at least one reference signal before transmitting the upcoming message.

20. The method according to claim 19, wherein the at least one reference signal is a synchronization signal or a Rado Resource Management, RRM, mobility measurement signal.

21. The method according to any of the claims 18-20, wherein transmitting (813) the WUS is performed when the wireless communications device (121) is in an idle or inactive Radio Resource Control, RRC, state.

22. The method according to any of the claims 18-21, wherein the WUS is sent on a physical channel other than a Physical Downlink Control Channel, PDCCH.

23. A wireless communications device (121) adapted to communicate in a wireless communications network (100) and to receive an upcoming message from the wireless communications network (100), the wireless communications device (121) comprising one or more Radio Frequency, RF, receivers (1110, 1120) and adapted to operate in a first power mode and a second power mode, and wherein a first power consumption of the one or more RF receivers (1110, 1120) in the first power mode is lower than a second power consumption of the one or more RF receivers (1110, 1120) in the second power mode and wherein the wireless communications device (121) is further adapted to:in the first power mode, receive, using the one or more RF receivers (1110, 1120), a Wake-Up Signal, WUS, from a radio access node (111) of the wireless communications network (100);obtain scheduling information of the upcoming message, wherein the scheduling information is indicated by the received WUS;in response to obtaining the scheduling information, activate the second power mode; andreceive, in the second power mode, the upcoming message using the one or more RF receivers (1110, 1120) based on the obtained scheduling information.

24. The wireless communications device (121) of claim 23, wherein the wireless communications device (121) is further configured to perform the method of any of the claims 2-17.

25. A radio access node (111) adapted to communicate in a wireless communications network (100) and to schedule an upcoming message from the wireless communications network (100) to a wireless communications device (121), wherein the radio access node (111) is further adapted to:transmit a WUS indicating scheduling information about the upcoming message to the wireless communications device (121); andtransmit the upcoming message to the wireless communications device (121) based on the scheduling information.

26. The radio access node (111) of claim 25, further configured to perform the method of any of the claims 19-22.

27. A computer program (1103), comprising computer readable code units which when executed on a processor of a wireless communications device (121) causes the wireless communications device (121) to perform the method according to any one of claims 1-17.

28. A computer program (1203), comprising computer readable code units which when executed on a radio access node (111) causes the radio access node (111) to perform the method according to any of the claims 18-22.

29. A carrier (1105, 1205) comprising the computer program (1103, 1203) according to claim 27 or 28, wherein the carrier (1105, 1205) is one of an electronic signal, an optical signal, a radio signal and a computer readable medium.

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