TECHNICAL FIELD

The present invention generally relates to a wireless device, and more particularly to support for a wireless device with a wake-up receiver.

BACKGROUND

A wireless device in a wireless communication network is typically configured to operate in a discontinuous reception (DRX) mode after a period of inactivity. In DRX mode, the wireless device is configured to receive information from the network only discontinuously in time. This relieves the wireless device from having to continuously monitor a downlink control channel (e.g., a physical downlink control channel, PDCCH) for downlink control information, including for instance paging messages intended for the device. Relieved from such continuous monitoring, the wireless device may operate in a sleep state when no information from the network is expected, e.g., by turning off at least some user equipment hardware/circuitry such as one or more receivers. Operating in a sleep state conserves the device's power and thereby prolongs the device's battery life.

Monitoring the downlink control channel, e.g., for paging messages, nonetheless consumes non-trivial amounts of power even when only monitored discontinuously in time.

SUMMARY

Power conservation may be realized through the use of a so-called wake-up signal. A wake-up signal is a physical signal that indicates the wireless device needs to awaken from a sleep state (or stay awaken) in order to monitor the downlink control channel, e.g., for paging messages. The decoding time for the wake-up signal may be considerably shorter than the decoding time for the downlink control channel. Accordingly, the wireless device may consume less power monitoring for a wake-up signal and may stay in the sleep state for longer.

Equipping a wireless device with a wake-up receiver enables even further power conservation. A wake-up receiver may be particularly designed and/or dedicated for receiving a wake-up signal, e.g. as a complement to another receiver of the device that is suitable for receiving the downlink control channel. A wake-up receiver may for instance have a lower requirement analog and radio frequency (RF) circuitry, and thereby power consumption, than a receiver capable of receiving the downlink control channel. A wake-up receiver therefore allows the wireless device to switch off one or more other receivers entirely until needed for decoding the control channel, so as to reach extremely low power consumption during sleep.

Some embodiments herein introduce signalling between a wireless device and a wireless communication network concerning the wireless device's wake-up receiver capability and/or the network's wake-up receiver capability/support. The network according to some embodiments schedules paging message(s) to the wireless device based on this signalling. The network may for instance delay transmitting paging message(s) to a wireless device with wake-up receiver capability (for longer than a device without wake-up receiver capability), to give the device time to awaken from a deep sleep state after detecting a wake-up signal with its wake-up receiver. Selectively giving a device with wake-up receiver capability extra time to awaken from a deep sleep state in this way proves advantageous in that it enables such a device to fully exploit the deep sleep state for maximum power conservation while still ensuring paging message delivery to the device. Moreover, some embodiments condition giving a device extra time to awaken from a deep sleep state on the network's ability to support that extra time, e.g., in order to safeguard latency demands placed on the network for inter-node signalling.

More particularly, embodiments herein include a method performed by a wireless device configured for use in a wireless communication network. The method comprises transmitting, to a network node in the wireless communication network, signaling indicating a minimum period that the wireless device requires between the end of a wake-up signal and the start of a paging occasion in order for the wireless device to be able to receive a paging message in that paging occasion. The method in some embodiments further comprises receiving, from a radio network node, signaling indicating a maximum period that the radio network node supports between the end of a wake-up signal and the start of a paging occasion.

In some embodiments, the method further comprises receiving a wake-up signal; and responsive to receiving the wake-up signal, monitoring for a paging message during a paging occasion that starts after at least the minimum period has passed since an end of the wake-up signal. In one such embodiment, the method may further comprise refraining from monitoring one or more other paging occasions that occur between the end of the received wake-up signal and the start of the paging occasion during which the wireless device monitors for a paging message. In other embodiments, the paging occasion is the first paging occasion that occurs within a paging transmission window for the wireless device, in which case the paging transmission window starts at least the minimum period since an end of the wake-up signal.

Alternatively or additionally, the minimum period indicated by the received signaling may be less than or equal to the maximum period supported by the radio network node. In this case, receiving the wake-up signal may comprise receiving the wake-up signal using a wake-up receiver. The method may then further comprise, responsive to receiving the wake-up signal, awakening the wireless device from a sleep state. This awakening may include activating one or more other receivers of the wireless device. Accordingly, monitoring may comprise, after awakening the wireless device from the sleep state, using the one or more other receivers to monitor for a paging message during a paging occasion that starts after at least the minimum period since an end of the wake-up signal.

In some embodiments, the indicated minimum period is a first wake-up period over which the wireless device is capable of awakening from a first sleep state. In this case, the method may further comprise, responsive to inactivity, determining whether or not to enter the first sleep state depending respectively on whether or not the first wake-up period is less than or equal to the maximum period supported by the radio network node. In the first sleep state, the wireless device is configured to monitor for a wake-up signal using a wake-up receiver. In one such embodiment, the method may further comprise, responsive to determining not to enter the first sleep state, entering a second sleep state, wherein the wireless device is configured to awaken from the second sleep state over a second wake-up period that is shorter in duration than the first wake-up period. The method may also comprise, in the second sleep state, monitoring for a wake-up signal using one or more other receivers that are different than the wake-up receiver.

In some embodiments, the wireless device has a wake-up receiver and one or more other receivers. The method in this case may further comprise monitoring for a wake-up signal using the wake-up receiver or the one or more other receivers, depending respectively on whether or not the indicated minimum period is less than the maximum period supported by the radio network node.

In some embodiments, the network node is core network node, wherein the core network node is a mobility management entity, MME, or implements an access and mobility function, AMF.

Embodiments herein also include a method performed by a radio network node configured for use in a wireless communication network. The method comprises receiving signaling indicating a minimum period that a wireless device requires between the end of a wake-up signal and the start of a paging occasion in order for the wireless device to be able to receive a paging message in that paging occasion. The method may also comprise transmitting to the wireless device signalling indicating a maximum period that the radio network node supports between the end of a wake-up signal and the start of a paging occasion.

In some embodiments, the method further comprises scheduling one or more paging messages to be transmitted to the wireless device, based on the received signalling and on whether the minimum period indicated by the received signaling is less than or equal to the maximum period supported by the radio network node. The method may then comprise transmitting the one or more paging messages as scheduled. In one such embodiment, scheduling comprises scheduling the one or more paging messages to be transmitted to the wireless device relatively later or earlier in time depending respectively on whether or not the period indicated by the received signaling is less than or equal to the maximum period supported by the radio network node, such that the one or more paging messages are transmitted later in time if the period indicated by the received signaling is less than or equal to the maximum period supported by the radio network node.

In some embodiments, the method comprises receiving a paging message from a network node in the wireless communication system. The paging message may be included the received signalling.

In some embodiments, the network node is core network node, wherein the core network node is a mobility management entity, MME, or implements an access and mobility function, AMF.

In some embodiments, the minimum period indicated by the received signaling is less than or equal to the maximum period supported by the radio network node. In this case, the method may further comprise transmitting a wake-up signal to the wireless device; and transmitting, to the wireless device, one or more paging messages during one or more paging occasions that each start after at least the minimum period has passed since an end of the wake-up signal.

Embodiments also include corresponding apparatus, computer programs, and computer-readable storage mediums. For example, embodiments include a wireless device configured for use in a wireless communication network. The wireless device is configured (e.g., via communication circuitry and processing circuitry) to transmit, to a network node in the wireless communication network, signaling indicating a minimum period that the wireless device requires between the end of a wake-up signal and the start of a paging occasion in order for the wireless device to be able to receive a paging message in that paging occasion. The wireless device in some embodiments is further configured to receive, from a radio network node, signaling indicating a maximum period that the radio network node supports between the end of a wake-up signal and the start of a paging occasion.

Embodiments further include a radio network node configured for use in a wireless communication network. The radio network node is configured (e.g., via communication circuitry and processing circuitry) to receive signaling indicating a minimum period that a wireless device requires between the end of a wake-up signal and the start of a paging occasion in order for the wireless device to be able to receive a paging message in that paging occasion. The radio network node may also be configured to transmit to the wireless device signalling indicating a maximum period that the radio network node supports between the end of a wake-up signal and the start of a paging occasion.

Of course, the present invention is not limited to the above features and advantages. Those of ordinary skill in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.

