LOW-POWER WIRELESS DEVICE

According to an example aspect of the present invention, there is provided an apparatus configured to determine a wake-up signal beam failure relating to a subset of configured wake-up signal beams in a cell, provide to a node controlling the cell a request to recover from the wake-up signal beam failure, the request comprising a list of wake-up signal beam identities ordered based on received signal strengths at which the respective wake-up signal beams are received at the apparatus, receive a response from the node controlling the cell, the response indicating a second subset of the configured wake-up signal beams in the cell, and begin monitoring the second subset of the configured wake-up signal beams.

FIELD

The present disclosure relates to transmission and reception arrangements in low-power wireless devices.

BACKGROUND

Wireless communication devices may be battery-powered, wherefore optimizing use of battery power has long been an aim in design of such devices.

Minimizing power drain increases the time a battery lasts before it needs to be recharged, which enhances the usability of the overall system as a more diverse set of use cases is enabled.

While personal communication devices, such as smartphones, may be recharged every few days, there are different wireless device types which are challengingto recharge frequently. For example, sensor devices installed in vehicles or buildings may be configured to provide information on liquid flow or temperature readings, or trigger fire alarms, for example, such that they aim to be powered by a stable power source, or a very long-lasting rechargeable or replaceable battery

SUMMARY

According to some aspects, there is provided the subject-matter of the independent claims. Some embodiments are defined in the dependent claims. The scope of protection sought for various embodiments of the invention is set out by the independent claims. The embodiments, examples 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 of the invention.

According to a first aspect of the present disclosure, there is provided an apparatus comprising at least one processing core and at least one memory storinginstructions that, when executed by the at least one processing core, cause the apparatus at least to determine a wake-up signal beam failure relating to a subset of configured wake-up signal beams in a cell, provide to a node controlling the cell a request to recover from the wake-up signal beam failure, the request comprising a list of wake-up signal beam identities ordered based on received signal strengths at which the respective wake-upsignal beams are received at the apparatus, receive a response from the node controlling the cell, the response indicating a second subset of the configured wake-up signal beams in the cell, and begin monitoring the second subset of the configured wake-up signal beams.

According to a second aspect of the present disclosure, there is provided an apparatus comprising at least one processing core and at least one memory storinginstructions that, when executed by the at least one processing core, cause the apparatus at least to receive, from a user equipment, a request to recover from a wake-up signal beam failure relating to a subset of configured wake-up signal beams in a cell controlled by the apparatus, the request comprising a list of wake-up signal beam identities ordered based on received signal strengths at which the respective wake-up signal beams are received at theuser equipment, and transmit a response to the user equipment, the response indicating a second subset of configured wake-up signal beams configured in the cell, the response instructing the user equipment to begin monitoring the second subset of the configured wake-up signal beams.

According to a third aspect of the present disclosure, there is provided a method comprising determining, by an apparatus, a wake-up signal beam failure relating to a subset of configured wake-up signal beams in a cell, providing to a node controlling the cell a request to recover from the wake-up signal beam failure, the request comprising a list of wake-up signal beam identities ordered based on received signal strengths at which the respective wake-up signal beams are received in the apparatus, receiving a response fromthe node controlling the cell, the response indicating a second subset of the configured wake-up signal beams in the cell, and beginning monitoring the second subset of the configured wake-up signal beams.

According to a fourth aspect of the present disclosure, there is provided a method, comprising receiving, in an apparatus, from a user equipment, a request to recover from a wake-up signal beam failure relating to a subset of configured wake-up signal beams in a cell controlled by the apparatus, the request comprising a list of wake-up signal beam identities ordered based on received signal strengths at which the respectivewake-up signal beams are received at the user equipment, and transmitting a response to the user equipment, the response indicating a second subset of configured wake-up signal beams configured in the cell, the response instructing the user equipment to begin monitoring the second subset of the configured wake-up signal beams.

According to a fifth aspect of the present disclosure, there is provided an apparatus comprising means for determining, by an apparatus, a wake-up signal beam failure relating to a subset of configured wake-up signal beams in a cell, providing to a node controlling the cell a request to recover from the wake-up signal beam failure, the request comprising a list of wake-up signal beam identities ordered based on received signal strengths at which the respective wake-up signal beams are received in theapparatus, and receiving a response from the node controlling the cell, the response indicating a second subset of the configured wake-up signal beams in the cell, and beginning monitoring the second subset of the configured wake-up signal beams.

According to a sixth aspect of the present disclosure, there is provided an apparatus comprising means for receiving, from a user equipment, a request to recoverfrom a wake-up signal beam failure relating to a subset of configured wake-up signal beams in a cell controlled by the apparatus, the request comprising a list of wake-up signal beam identities ordered based on received signal strengths at which the respective wake-up signal beams are received at the user equipment, and transmitting a response to the user equipment, the response indicating a second subset of configured wake-up signal beamsconfigured in the cell, the response instructing the user equipment to begin monitoring the second subset of the configured wake-up signal beams.

According to a seventh aspect of the present disclosure, there is provided a non-transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at leastdetermine a wake-up signal beam failure relating to a subset of configured wake-up signal beams in a cell, provide to a node controlling the cell a request to recover from the wake-up signal beam failure, the request comprising a list of wake-up signal beam identities ordered based on received signal strengths at which the respective wake-up signal beams are received in the apparatus, and receive a response from the node controlling the cell, the response indicating a second subset of the configured wake-up signal beams in the cell, and begin monitoring the second subset of the configured wake-up signal beams.

According to an eighth aspect of the present disclosure, there is provided anon-transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least receive, from a user equipment, a request to recover from a wake-up signal beam failure relating to a subset of configured wake-up signal beams in a cell controlled by the apparatus, the request comprising a list of wake-up signal beam identities ordered based onreceived signal strengths at which the respective wake-up signal beams are received at the user equipment, and transmit a response to the user equipment, the response indicating a second subset of configured wake-up signal beams configured in the cell, the response instructing the user equipment to begin monitoring the second subset of the configured wake-up signal beams.

DETAILED DESCRIPTION

Methods are disclosed herein to enhance the use of wake-up signalling with beamforming, wherein a user equipment, UE, at least in some cases, needs to monitor only a proper subset of all configured wake-up signal beams in a cell. In some cases, the UE might monitor all the wake-up signal beams in a cell, for example if the cell is small. Afterdetecting a wake-up signal beam failure, a UE may request recovery from the wake-up signal beam failure by transmitting a request to the base station controlling the cell, the request including information on a sequence of the wake-up signal beams ordered based on their received signal strengths, for example, the transmission may comprise a list of wake-up signal beams of the cell arranged in a list based on received signal strengths of therespective wake-up signal beams. The base station may, based on the list, revise the subset of wake-up signal beams that the UE should monitor, to recover from the wake-up signal beam failure. A beam may also be referred to as a transmission configuration indication, TCI, or a transmission configuration indication state.

FIG.1Aillustrates an example system in accordance with at least some embodiments of the present invention. A base node130, such as a cellular base station130, is configured to operate based on a suitable technical standard, such as long term evolution, LTE, fifth generation, 5G, or 6G, for example. A base station may be referred to as a radio node, network node, node, eNode B, eNB, or gNB network device. A base station is a node configured to control one or more cell(s). The base station may comprise a centralized unit,gNB-CU, and one or more distributed unit, gNB-DU. A gNB-CU and gNB-DU(s) may be connected using e.g. an F1 interface. Another term for 5G is new radio, NR. A yet further example of a suitable technical standard is 5G-Advanced. Alternatively, base node130may be a non-cellular base node, such as, for example, a wireless local area network, WLAN, or worldwide interoperability for microwave access, WiMAX, access point.

In addition to base node130, the system ofFIG.1also includes two user equipments, UEs,110,120. A UE may be referred to as a terminal, a terminal device, auser device or simply a device. The UEs110,120comprise as a main radio, MR, a wireless transceiver configured to communicate using a cellular or non-cellular radio technology, such as one of those mentioned above, for example, to obtain interoperation with base node130. A user equipment110,120may comprise, for example, an Internet ofThings, IoT, node, such as a sensor node, or a utility meter which is not an IoT node. UEs110,120are illustrated as including a display screen, however this is by no means compulsory as many UEs suitable for use with the presently disclosed mechanisms are optimized for low power consumption and may well lack visual display screens. Rather, these UEs may be configured to provide, for example, an uplink transmission to base node130when requested, or according to a pre-configured time schedule for reporting. The uplink transmission may comprise sensor data generated by the respective UE110,120, or mesh-network data, for example, received in the UEs110,120from further devices, which are not illustrated inFIG.1Afor the sake of clarity of the illustration. Radio links131,132connect base station130to UE110and120, respectively.

UEs110,120are configured to spend time in an energy saving state when not transmitting or receiving via the wireless transceiver. The energy saving state comprises that the wireless transceiver of the UE110,120is in a low-power state. The low-power state of the wireless transceiver may be one where the wireless transceiver is switched off, or placed in a hibernated or otherwise inactive state where the wirelesstransceiver does not monitor for incoming transmissions and does not transmit signals. Further examples of names used of the hibernated or inactive state are discontinuous reception, DRX, sleep state, DRX-Off state, RRC_Idle and RRC_Inactive state.

The energy saving state may be extensive and extend also to other systems of UE110,120than the wireless transceiver. UEs110,120may be powered by a non-rechargeablebattery which aims to power the UEs110,120for months, or even a year, wherefore optimization of power consumption needs to be conducted carefully. In particular, monitoring for transmissions using a cellular or non-cellular radio technology such as the ones mentioned above, for example, consumes necessarily so much power that in the UEs110,120ofFIG.1A, these radio technologies are not used in the energy savingstate. To enable communication with a UE110,120in the energy saving state, the UEs110,120are equipped with a wireless receiver which is separate from the wireless transceiver which is usable with the cellular or non-cellular technology to receive modulated payload data from the wireless communication system. Base node130mayprovide a signal, such as a wake-up signal, that the wireless receiver is configured to detect. The wireless receiver may be referred to, for example, as a low-power receiver, an ultra-low power receiver or a wake-up receiver, WUR. Responsive to the signal, the UE that received the signal switches its wireless transceiver from the low-power state to anactive state. Examples of the active state include radio resource control, RRC_Active, DRX-On and DRX-Active. In the active state, the wireless transceiver is able to receive and/or transmit information based on the cellular or non-cellular radio technology that the UE is configured to use. Initially in the active state, the device may be in an RRC_Idle state, from which an RRC connection may be established whereby the state is switched toRRC_Connected. The wireless transceiver is the main radio of the UE, while the wireless receiver is used to receive the signal to end the energy saving state.

When the UE is in the energy saving state, it may be in an RRC_Inactive state, where the UE may behave similarly to when it is in the RRC_Idle state. In RRC_Inactive state, the Access Stratum, AS, context is stored by both UE and base station,as a result of which the state transition from inactive state to connected state is faster. In the RRC_Inactive state, the UE cannot transmit anything in the uplink except for physical random access channel, PRACH, as part of random access procedure initiated when UE desires to transit to RRC_Connected state (to transmit RRCResumeRequest) or to request for On-demand system information. The base station can send a UE from RRC_Connectedto RRC_Inactive state by transmitting a RRCRelease message. The resumption of a suspended RRC connection may be initiated by upper layers when the UE needs to transition from RRC_Inactive state to RRC_Connected state, or by the RRC layer to perform an RAN Notification Area, RNA, update or by RAN paging.

In the situation ofFIG.1A, UE110has a clearer radio path to base node130, wherefore a signal transmitted from base node130to UE110is received with less path loss than a signal transmitted from base node130to UE120. In general UE120may be further away from base node130, but this is not necessarily the case since the radio paths may be more complex in nature and include reflections from objects, which incur path loss without necessarily involving great distances. To provide a signal to UE120, the signalmay be transmitted from base node130using a higher transmit power, and/or using a larger number of repetitions. Repetitions may take place sequentially in time, and/or at least in part concurrently in time, using a different frequency. The repetitions may be combined in UE120by integrating on-duration energy and off-duration energy not only from one transmission, but from plural transmissions, for example. On-duration is the predefined portion of the transmission containing signal, while the rest of the transmission is off-duration. Off-duration energy may be used e.g. for determining a detection threshold. Base node130may transmit the first wake-up signal with the smallest repetition, or withno repetition, estimated sufficient for a specific UE.

Wake-up signals may be provided to groups of UEs, such that UEs are divided to multiple preconfigured groups. A group wake-up signal, GWUS, may be transmitted when there is a paging message for any UE belonging to the corresponding group. GWUS is different for each group. The GWUS configuration may be provided insystem information, for example. GWUS transmissions for different groups may be multiplexed, and UEs in multiple groups in different resources may be signaled before a paging opportunity. A common wake-up signal may be configured for a wake-up signal resource to wake up UEs from all groups that are monitoring GWUS in a resource. Therefore, a UE may be configured to monitor both a group-specific GWUS and acommon wake-up signal.

When a UE doesn't detect a wake-up signal successfully for a period, it cannot in principle know whether a wake-up signal is not transmitted, or if the channel quality of the link used to convey the wake-up signal is too low. Therefore, a reference signal, such as a beacon signal, can be transmitted periodically, for example at aperiodicity smaller or greater than the normal rate of paging. The beacon may be transmitted over all wake-up signal beams configured in the cell. Furthermore, the beacon signal can be also used to provide timing to the WUR. For simplicity of WUR processing, the waveform of a low-power beacon signal can be the same as that of a wake-up signal. A UE can also use the beacons to calculate a received signal power, RSP, of wake-up signalbeams in the cell, and leverage the RSP for radio resource management. The RSP may be defined as the average signal power (Total power−[Noise+interference power]) evaluated over a bit duration of the wake-up signal, for example.

FIG.1Billustrates an example of wake-up signal beamforming use. Like numbering denotes like structure as inFIG.1A. Wake-up signals are here transmitted in adirectional manner in wake-up signal beams, which may be distinct from beams used in cellular data communication. The wake-up signal beams may be used exclusively for wake-up signal and wake-up beacon provision to UEs. Using beamforming enhances therange at which the wake-up signal may be received, which is useful since the wake-up wireless receiver of a UE may be simpler in function than the wireless transceiver of the UE, and thus less capable of detecting very weak signals.

UEs110,120may be configured with proper subsets of the entire set of wake-up signal beams140a-140econfigured in a cell, to monitor. The monitoring may be in RRC_Inactive state, for example. In at least some embodiments, the subset may be deleted in the base station when the UE is in RRC_Idle state, as in the RRC_Idle state the UE context will be deleted in the base station. For example, UE110may be configured to monitor a subset comprising only beams140aand140b, while UE120may be configuredto monitor a subset comprising only beam140e. This provides the dual benefit, that wake-up signals for these UEs need not be transmitted in all beams, resulting in more efficient use of wake-up signal resources, and the UEs need not monitor all the beams. By proper subset of beams it is meant a subset of the set of all configured beams, which does not comprise all the beams in the set of all configured beams. Each UE is configured torespond to a wake-up signal for the UE conveyed over at least one of the beams in the subset of beams the UE is configured to monitor.

FIG.2Aillustrates a wake-up signal beamforming use. In the situation ofFIG.2A, UE110is configured to monitor a subset of wake-up signal beams, the subset comprising beams140aand140bonly. The beams of the subset are striped in the figurefor clarity. This subset is a proper subset of all configured wake-up signal beams in the cell,140a,140b,140c,140dand140e. UE110measures an RSP of wake-up signal beams in its configured subset by measuring a wake-up signal beacon provided by base station130over these wake-up signal beams. As long as the RSP remains in an acceptable range, for example in terms of exceeding a threshold with respect to the noise floor, the UE mayconsider the wake-up signal beams of the subset to be in working order.

FIG.2Billustrates a wake-up signal beamforming use. Like numbering denotes like structure as inFIG.2A, and the situation ofFIG.2Boccurs after the situation ofFIG.2A. Here UE110has moved geographically in the cell, such that the beams of the subset,140aand140b, are no longer directed toward the UE. Here the UE may continue toperiodically, for example using a fixed, constant periodicity, determine the RSP of the beams in the subset. As the beams are no longer aligned with the geographic location ofUE110, their RSP measured from the current location of UE110may be very low, falling below the threshold.

Responsive to all the wake-up signal beams in the configured subset falling below the RSP threshold, the UE may determine that it is in a wake-up signal beam failuresituation. Such an event may also be referred to as a wake-up signal beam failure relating to a subset of configured wake-up signal beams in a cell. In the wake-up signal beam failure situation, the UE may provide to base station130a request to recover from the wake-up signal beam failure. This request comprises a list of wake-up signal beam identities ordered based on received signal strengths at which the respective wake-upsignal beams are received in UE110. The wake-up signal beam identities may be, for example, TCIs, TCI identities, TCI states or TCI state identities. Alternatively, the request comprises a list of received signal strengths of wake-up signal beams ordered based on wake-up signal beam identities. The request also comprises an implicit or explicit indication that a wake-up signal beam failure has occurred. The order may be in ascendingor in descending order. To compile the request, UE110may measure all wake-up beam signal RSPs, not just those in its subset, for example using the wake-up signal beam beacon transmission described above. The request may be provided from UE110to the base station without transitioning the UE away from a RRC_Inactive state. For example, the request may be transmitted using a random access process, RRC signalling or mediumaccess control, MAC, control element signalling. Such signalling may take place on the PRACH, for example. The random access process may be a two-step or a four-step random access process, for example. An advantage of maintaining the UE in RRC_Inactive state is conservation of power, since RRC_Inactive is an energy saving state. Further, leaving and re-entering the RRC_Inactive state involves signalling, which is avoided if UE110can bekept in the RRC_Inactive state.

In some embodiments UE110is configured to include in the list only those wake-up signal beams which have RSPs over a second threshold. This serves the purpose to make the request smaller and thus easier to signal toward the base station. Further, there is no real drawback, as the base station would not select very weak wake-up signal beamsin the new subset for the UE to monitor. As a variant of this, the UE may be configured to include in the list at least the strongest, or the two strongest, wake-up signal beams in terms of RSP, even if they do not reach the second threshold. In some embodiments, the second threshold and the threshold the UE uses to determine a wake-up signal beams failure is the same threshold. In other embodiments, the thresholds are not set at the same level.

The base station, in receipt of the request to recover from the wake-up signal beam failure, may choose for UE110a new subset of wake-up signal beams to monitor,for example, it may choose the strongest beam or beams from the ordered list of wake-up beam identities provided by the UE in the request. Thus UE110may monitor the new subset of wake-up signal beams and it will not need to monitor all the wake-up signal beams in the cell.

The base station may provide an indication of the new subset to UE110without causing UE110to leave the RRC_Inactive state, for example using downlink signalling on the PRACH to provide a response to the request to recover from the wake-up signal beam failure. For example, the response may be provided in the downlink direction using a random access process, RRC signalling or medium access control, MAC, control element signalling. The random access process may be a 2-step or a 4-step random accessprocess. For example, where the random access process is a 2-step process, the first step may be the request to recover from the wake-up signal beam failure and the second step may be the response from the base station. In some embodiments, the request is sent from the UE as a RRCResumeRequest or RRCResumeRequest1 message with the request message therein, and the base station transmits the response in a RRCRelease withsuspendconfig message.

In one embodiment, the UE can send a request MAC control element, CE, to convey the request message to the base station. The request MAC CE may have a variable length, primarily because the number of reported candidate beams having RSP above the minimum threshold can vary. The base station on reception of request MAC CE can sendthe corresponding response message meant for the specific UE using response MAC CE.

Once UE110has the response, it may update its subset of wake-up signal beams such that it will subsequently monitor only the wake-up signal beams in the new subset. Monitoring of the wake-up signal beams in the original subset is discontinued, unless per chance one or more wake-up signal beams of the original subset is also in thenew subset, which is not likely since the wake-up signal beam failure occurred when all the beams in the original subset were below the RSP threshold. The UE may send the request, and receive the response, using its main radio, the wireless transceiver.

While described herein as being determined responsive to all the wake-up signal beams in the original subset being below an RSP threshold, in various embodiments the wake-up signal beams failure may be determined on other ways as well. Further, the exact method used by the base station to select the new subset of wake-up signal beamsmay comprise further selection criteria than merely the order of beams in the list provided by the UE in the request. For example, the base station may consider whether the wake-up signal beams with highest RSP are available for this UE within wake-up signal groups that are relevant to this UE. If yes, they may be chosen to the new subset. If not, the base station may consider a lower-priority wake-up signal group and select a strong beam fromamong those resources, even if these beams are not the altogether strongest ones in the list received from the UE.

To enable the cell-specific wake-up signal tracking area, CWTA, update in RRC_Inactive state, the UE may be configured to send a RRCResumeRequest or RRCResumeRequest1 message with a CWTA-Update ResumeCause. The CWTA maycorrespond to the subset of wake-up signal beams configured in a cell for a specific UE. This enables CWTA update in RRC_Inactive state using the wake-up signal beam failure recovery request and response message exchange. Within a cell the base station may allocate a specific candidate set of beams of the UE, which can be termed the CWTA, by taking into account the mobility pattern of the UE and its surronding environment. TheCWTA is valid when the UE context is stored at the base station, that is, during RRC Inactive and RRC_Connected mode. A wake-up signal beam failure recovery may lead to a CWTA update.

To transmit the wake-up signal beam failure recovery request to the base station, the UE may start up its wireless transceiver for communicating the request andresponse thereto with the base station. The UE may use the information it has determined for wake-up signal beam RSPs to facilitate choosing a cellular synchronization signal block, SSB, beam for communicating the request and response with the base station. In some systems, there is a one-to-one correspondence between wake-up signal beams and, SSB beams in which case the UE can simply attach to the SSB beam corresponding to thewake-up signal beam with strongest RSP. In systems without a one-to-one correspondence between the beam types, there may be a different type of correspondence, usable in facilitating choice of a SSB beam to attach to bases on the RSP values of the wake-up signal beams. A synchronization signal block beam may be referred to as an SSB index, aSSB transmission configuration indication, an SSB TCI state, an SSB TCI state index, an SSB state identity, an SSB TCI index or an SSB TCI identity.

FIG.3illustrates an example apparatus capable of supporting at least some embodiments of the present invention. Illustrated is device300, which maycomprise, for example, a mobile communication device such as UE110ofFIG.1or, in applicable parts, a base station. Comprised in device300is processor310, which may comprise, for example, a single- or multi-core processor wherein a single-core processor comprises one processing core and a multi-core processor comprises more than one processing core. Processor310may comprise, in general, a control device. Processor310may comprise more than one processor. When processor310comprises more than one processor, device300may be a distributed device wherein processing of tasks takes place in more than one physical unit. Processor310may be a control device. A processing core may comprise, for example, a Cortex-A8 processing core manufactured by ARM Holdings or a Zen processing core designed by Advanced Micro Devices Corporation. Processor310may comprise at least one Qualcomm Snapdragon and/or Intel Atom processor. Processor310may comprise at least one application-specific integrated circuit, ASIC. Processor310may comprise at least one field-programmable gate array, FPGA. Processor310may be means for performing method steps in device300, such as determining, providing, receiving, monitoring, performing, receiving and transmitting. Processor310may beconfigured, at least in part by computer instructions, to perform actions.

Device300may comprise memory320. Memory320may comprise random-access memory and/or permanent memory. Memory320may comprise at least one RAM chip. Memory320may comprise solid-state, magnetic, optical and/or holographic memory, for example. Memory320may be at least in part accessible to processor310. Memory320may be at least in part comprised in processor310. Memory320may be means for storing information. Memory320may comprise computer instructions thatprocessor310is configured to execute. When computer instructions configured to cause processor310to perform certain actions are stored in memory320, and device300overall is configured to run under the direction of processor310using computer instructions from memory320, processor310and/or its at least one processing core may be considered to be configured to perform said certain actions. Memory320may be at least in part comprisedin processor310. Memory320may be at least in part external to device300but accessible to device300. Memory320may be non-transitory. The term “non-transitory”, as used herein, is a limitation of the medium itself (that is, tangible, not a signal) as opposed to a limitation on data storage persistency (for example, RAM vs. ROM).

Device300may comprise a transmitter330. Device300may comprise areceiver340. Transmitter330and receiver340may be configured to transmit and receive, respectively, information in accordance with at least one cellular or non-cellular standard. Transmitter330may comprise more than one transmitter. Receiver340may comprise more than one receiver. Transmitter330and/or receiver340may be configured to operate in accordance with global system for mobile communication, GSM, wideband codedivision multiple access, WCDMA, 6G, 5G, long term evolution, LTE, IS-95, wireless local area network, WLAN, Ethernet and/or worldwide interoperability for microwave access, WiMAX, standards, for example.

Device300may comprise user interface, UI,360. UI360may comprise at least one of a display, a keyboard, a touchscreen, a vibrator arranged to signal to a user by causing device300to vibrate, a speaker and a microphone. A user may be able to operate device300via UI360, for example to accept incoming telephone calls, to originate telephone calls or video calls, to browse the Internet, to manage digital files stored in memory320or on a cloud accessible via transmitter330and receiver340, or via NFCtransceiver350, and/or to play games.

Device300may comprise or be arranged to accept a user identity module370. User identity module370may comprise, for example, a subscriber identity module, SIM, card installable in device300. A user identity module370may comprise information identifying a subscription of a user of device300. A user identity module370maycomprise cryptographic information usable to verify the identity of a user of device300and/or to facilitate encryption of communicated information and billing of the user of device300for communication effected via device300.

Processor310may be furnished with a transmitter arranged to output information from processor310, via electrical leads internal to device300, to other devicescomprised in device300. Such a transmitter may comprise a serial bus transmitter arranged to, for example, output information via at least one electrical lead to memory320for storage therein. Alternatively to a serial bus, the transmitter may comprise a parallel bus transmitter. Likewise processor310may comprise a receiver arranged to receive information in processor310, via electrical leads internal to device300, from other devicescomprised in device300. Such a receiver may comprise a serial bus receiver arranged to, for example, receive information via at least one electrical lead from receiver340for processing in processor310. Alternatively to a serial bus, the receiver may comprise a parallel bus receiver.

Device300may comprise further devices not illustrated inFIG.3. For 30 example, where device300comprises a smartphone, it may comprise at least one digital camera. Some devices300may comprise a back-facing camera and a front-facing camera, wherein the back-facing camera may be intended for digital photography and the front-facingcamera for video telephony. Device300may comprise a fingerprint sensor arranged to authenticate, at least in part, a user of device300. In some embodiments, device300lacks at least one device described above. For example, some devices300may lack a NFC transceiver350and/or user identity module370.

Processor310, memory320, transmitter330, receiver340, NFC transceiver350, UI360and/or user identity module370may be interconnected by electrical leads internal to device300in a multitude of different ways. For example, each of the aforementioned devices may be separately connected to a master bus internal to device300, to allow for the devices to exchange information. However, as the skilled person willappreciate, this is only one example and depending on the embodiment various ways of interconnecting at least two of the aforementioned devices may be selected without departing from the scope of the present invention.

FIG.4illustrates signalling in accordance with at least some embodiments of the present invention. On the vertical axes are disposed, on the left, UE110ofFIG.1, comprising the wireless transceiver MR and the wireless receiver WUR, and on the right, base station130. Time advances from the top toward the bottom. UE110is in the RRC_INACTIVE state throughout this process.

In phase410, UE110determines a wake-up beam failure, using the WUR, for example by determining that wake-up signal beams in its configured subset are below athreshold. This may be based on beacon transmissions on these wake-up signal beams, for example. In phase420, which in some cases may precede phase410, RSPs of all wake-up signal beams in the cell are determined by UE110, using the WUR. The threshold may be−90 dBm, for example. The threshold may be configurable, or a hard-coded requirement defined in a standard, for example.

In phase430, UE110switches its wireless transceiver MR on. While the arrow of phase430inFIG.4begins in the WUR, UE110may alternatively switch on the MR from a processor, for example. In phase440, the wireless transceiver MR is activated, and in phase450wireless transceiver MR synchronizes with an SSB beam, for example the strongest one. As described above, the wake-up signal beam RSPs determined in phase420may assist in selecting the strongest SSB beam, in case there is a meaningful correspondence between wake-up signal beams and SSB beams. Alternatively, the MRmay measure which SSB beam is strongest and synchronize then with the strongest SSB beam.

In phase460, UE110provides the request to recover from a wake-up signal beam failure to base station130. This request and method of its delivery have beendescribed herein above. The request comprises an list of wake-up signal beams, or their identities, ordered in order of their RSPs as measured in phase420. In phase470the base station determines a new subset of wake-up signal beams for UE110to monitor, based at least in part on the list received in phase460in the request from the UE.

In phase480, the base station responds to the request by providing the response, the response comprising the new subset of wake-up signal beams for UE110to monitor, instead of the original subset. In phase490, the UE110switches the wireless transceiver MR off, to continue monitoring of the wake-up signal beams using the new subset received from the base station in phase480. In at least some embodiments, phases460and480are accomplished while maintaining UE110in RRC_Inactive state.

FIG.5is a flow graph of a method in accordance with at least some embodiments of the present invention. The phases of the illustrated method may be performed in UE110, or in a control device configured to control the functioning thereof, when installed therein.

Phase510comprises determining, by an apparatus, a wake-up signal beam failure relating to a subset of configured wake-up signal beams in a cell. Phase520comprises providing to a node controlling the cell a request to recover from the wake-up signal beam failure, the request comprising a list of wake-up signal beam identities ordered based on received signal strengths at which the respective wake-up signal beams are received in the apparatus. Phase530comprises receiving a response from the nodecontrolling the cell, the response indicating a second subset of the configured wake-up signal beams in the cell, and beginning monitoring the second subset of the configured wake-up signal beams.

FIG.6is a flow graph of a method in accordance with at least some embodiments of the present invention. The phases of the illustrated method may beperformed in base station130, or in a control device configured to control the functioning thereof, when installed therein.

Phase610comprises receiving, in an apparatus, from a user equipment, a request to recover from a wake-up signal beam failure relating to a subset of configured wake-up signal beams in a cell controlled by the apparatus, the request comprising a list of wake-up signal beam identities ordered based on received signal strengths at which therespective wake-up signal beams are received at the user equipment. Finally, phase620comprises transmitting a response to the user equipment, the response indicating a second subset of configured wake-up signal beams configured in the cell, the response instructing the user equipment to begin monitoring the second subset of the configured wake-up signal beams.

INDUSTRIAL APPLICABILITY

At least some embodiments of the present invention find industrial application in managing connectivity with low-power wireless devices.

ACRONYMS LIST

PRACH physical random access channelRSP received signal powerRRC radio resource controlSSB synchronization signal blockWUR wake-up receiver

REFERENCE SIGNS LIST110, 120user equipment130base station131, 132radio links140a-140ewake-up signal beams300-370structure of the device of FIG. 3410-490phases of the process of FIG. 4.510-530phases of the method of FIG. 5610-620phases of the method of FIG. 6