WO2023048634A1 - Network energy saving - Google Patents

Abstract

A network node (16), a wireless device (22), and associated methods and systems are disclosed. The network node monitors for receipt of a wake-up signal, WUS, from thewireless device, and performs at least one of the following three actions in response to receipt of the WUS: transmitting synchronization signal blocks, SSBs; transmitting system information; and monitoring physical random access channel, PRACH, occasions for receipt of a PRACH preamble. The wireless device transmits the WUS to the network node and performs at least one of the following three actions after transmission of the WUS: receiving a SSB from the network node; receiving system information from the network node; transmitting a PRACH preamble to the network node.

Description

NETWORK ENERGY SAVING

TECHNICAL FIELD

The present disclosure relates to wireless communications, and in particular, to wake up signals (WUS) for a base station (such as a New Radio (NR) base station) for network energy savings.

BACKGROUND

The Third Generation Partnership Project (3GPP) has developed and is developing standards for Fourth Generation (4G) (also referred to as Long Term Evolution (LTE)) and Fifth Generation (5G) (also referred to as New Radio (NR)) wireless communication systems. Such systems provide, among other features, broadband communication between network nodes, such as base stations, and mobile wireless devices (WD), as well as communication between network nodes and between WDs. Sixth Generation (6G) wireless communication systems are also under development.

Wireless communication systems according to the 3 GPP may include the one or more of the following channels:

• a physical downlink control channel, PDCCH;

• a physical uplink control channel, PUCCH;

• a physical downlink shared channel, PDSCH;

• a physical uplink shared channel, PUSCH;

• a physical broadcast channel, PBCH; and

• a physical random access channel, PRACH.

Network Energy Consumption

Always-on reference signals in LTE have limited the energy efficiency of the network, and lean signal design in NR enables periodic reference signals. Hence, it is expected that NR can improve the energy efficiency of the network. However, NR in the current implementation will most likely consume more power compared to LTE, partly due to higher bandwidth (BW) and massive numbers of antennas. This is still evident even if there are no WDs present in a cell (network idle mode). Although there is no uplink (UL) or downlink (DL) transmission between a specific WD and a New Radio base station (gNB, hereinafter referred to as a network node) in idle mode, the network node still needs to periodically transmit signals, such as synchronization signal block (SSB) and broadcast system information (SI), e.g., SIB1. In addition, the network node also needs to periodically monitor the preambles from a WD to cope with random access. For example, PRACH slots can be configured every frame. Hence, the transmitter and receiver components of the network node need to be turned on periodically even if the network node is in idle mode, thereby consuming energy.

Network Sleep Time

In LTE, there are frequent transmissions of always-on signals, for example, cell specific reference signals (CRSs). As a result, there are only very short durations (less than 1 millisecond) for the base station to sleep until the next required signal transmission occurs and only a small number of components with very fast transition times can therefore be switched off when the base station is in idle mode. This limits the possible energy savings of LTE. In NR, the network node only transmits SSBs and configured system information (SI) in idle mode as per 3 GPP Technical Standard (TS) 38.213, and the periodicity of these signals can be extended to hundreds of milliseconds. This, in turn, allows for both deeper and longer periods of sleep when there is no ongoing data transmission, which has a significant impact on the overall network energy consumption. For example, SSBs can be configured with 20ms periodicity. Therefore, a network node can switch on its transmitters every 20ms for SSB transmission and then switch them off for sleep. The longer periodicity of SSB brings longer sleep time of the network node transmitters. A longer sleep time makes it possible to switch off more components which have a few millisecond transitions time and achieve a deeper sleep. For example, a 20ms or longer sleep time makes it possible for the digital front-end or baseband components to lie dormant, thereby saving more energy. This not only reduces the energy consumed by the transmitted signals. In addition, the receivers can also be switched on during PRACH occasions and switched off at other moments for sleep when a network node is in idle mode.

In NR, due to higher BW and massive numbers of antennas, the energy consumed by transmitting periodic signals (SSB and SI) in idle mode is not negligible. The longer periodicity of the periodic signals entails the longer sleep time of the network node in idle mode, which implies more components of the advanced antenna unit (AAU) and baseband unit (BBU) may enter the sleep state. As a result, the energy efficiency of network is improved.

However, an extended transmission periodicity of the periodic signals also implies that the random access channel (RACH) opportunities are reduced for the WDs of the cell, and the time required for WD accessing the network through the PRACH is prolonged (i.e., increased access latency), as per the 3GPP Technical Standard (TS) 38.213 and 3GPP TS 38.321. For example, if both SSB and SIB1 are configured with 160ms periodicity, and a WD doesn’t receive the current SSB and SIB1, then this WD must wait for at least 160ms for its next PRACH occasions.

Evidently, simply adjusting the periodicity of the periodic signals doesn't improve energy efficiency and network performance simultaneously.

Furthermore, previous solutions for modifying the network node operation and the related power level rely on a “side connection” with reference to the cell in question to change or otherwise activate the SSB period. This approach does not function if there are no such side connections. Stated in another way, the approach does not function if there is no connection via a different frequency layer, or via a neighbor network node invoking the intended network node, for example.

SUMMARY

A first aspect provides embodiments of a method implemented in a network node. The method comprises monitoring for receipt of a wake-up signal (WUS) from a wireless device, and performing at least one of the following three actions in response to receipt of the WUS: transmitting synchronization signal blocks (SSBs); transmitting system information; monitoring physical random access channel (PRACH) occasions for receipt of a PRACH preamble.

A second aspect provides embodiments of a network node configured to perform the method of any of the embodiments of the first aspect.

A third aspect provides embodiments of a method implemented in a wireless device. The method comprises transmitting a WUS to a network node, and performing at least one of the following three actions after transmission of the WUS: receiving a SSB from the network node; receiving system information from the network node; transmitting a PRACH preamble to the network node. A fourth aspect provides embodiments of a wireless device configured to perform the method of any of the embodiments of the third aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. l is a schematic diagram of an example network architecture illustrating a communication system connected via an intermediate network to a host computer according to some embodiments of the present disclosure;

FIG. 2 is a block diagram of a host computer communicating via a network node with a wireless device over an at least partially wireless connection according to some embodiments of the present disclosure;

FIG. 3 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for executing a client application at a wireless device according to some embodiments of the present disclosure;

FIG. 4 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for receiving user data at a wireless device according to some embodiments of the present disclosure;

FIG. 5 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for receiving user data from the wireless device at a host computer according to some embodiments of the present disclosure;

FIG. 6 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for receiving user data at a host computer according to some embodiments of the present disclosure;

FIG. 7 is a flowchart of an example process in a network node for wake up signals (WUS) for network energy savings; FIG. 8 illustrates switching off transmitters according to some embodiments of the present disclosure;

FIG. 9 illustrates examples of WUS-based network node configurations; and FIG. 10 illustrates more examples of WUS-based network node configurations.

DETAILED DESCRIPTION

Before describing in detail example embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to wake up signals (WUS) for a base stations (such as new radio, NR, base stations) for network energy savings. Accordingly, components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Like numbers refer to like elements throughout the description.

As used herein, relational terms, such as “first” and “second,” “top” and “bottom,” and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

In embodiments described herein, the joining term, “in communication with” and the like, may be used to indicate electrical or data communication, which may be accomplished by physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling or optical signaling, for example. One having ordinary skill in the art will appreciate that multiple components may interoperate and modifications and variations are possible of achieving the electrical and data communication.

In some embodiments described herein, the term “coupled,” “connected,” and the like, may be used herein to indicate a connection, although not necessarily directly, and may include wired and/or wireless connections.

The term “network node” used herein can be any kind of network node comprised in a radio network which may further comprise any of base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), g Node B (gNB), evolved Node B (eNB or eNodeB), Node B, multi-standard radio (MSR) radio node such as MSR BS, multi-cell/multicast coordination entity (MCE), integrated access and backhaul (IAB) node, relay node, donor node controlling relay, radio access point (AP), transmission points, transmission nodes, Remote Radio Unit (RRU) Remote Radio Head (RRH), a core network node (e.g., mobile management entity (MME), self-organizing network (SON) node, a coordinating node, positioning node, MDT node, etc.), an external node (e.g., 3rd party node, a node external to the current network), nodes in distributed antenna system (DAS), a spectrum access system (SAS) node, an element management system (EMS), etc. The network node may also comprise test equipment. The term “radio node” used herein may be used to also denote a wireless device (WD) or a radio network node.

In some embodiments, the non-limiting terms wireless device (WD) or a user equipment (UE) are used interchangeably. The WD herein can be any type of wireless device capable of communicating with a network node or another WD over radio signals. The WD may also be a radio communication device, target device, device to device (D2D) WD, machine type WD or WD capable of machine to machine communication (M2M), low-cost and/or low-complexity WD, a sensor equipped with WD, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), an Internet of Things (loT) device, or a Narrowband loT (NB-IOT) device, etc.

Also, in some embodiments the generic term “radio network node” is used. It can be any kind of a radio network node which may comprise any of base station, radio base station, base transceiver station, base station controller, network controller, RNC, evolved Node B (eNB), Node B, network node, Multi-cell/multicast Coordination Entity (MCE), IAB node, relay node, access point, radio access point, Remote Radio Unit (RRU) Remote Radio Head (RRH).

Note that although terminology from one particular wireless system, such as, for example, 3GPP LTE and/or New Radio (NR), may be used in this disclosure, this should not be seen as limiting the scope of the disclosure to only the aforementioned system. Other wireless systems, including without limitation Wide Band Code Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) and Global System for Mobile Communications (GSM), may also benefit from exploiting the ideas covered within this disclosure.

Note further, that functions described herein as being performed by a wireless device or a network node may be distributed over a plurality of wireless devices and/or network nodes. In other words, it is contemplated that the functions of the network node and wireless device described herein are not limited to performance by a single physical device and, in fact, can be distributed among several physical devices.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Some embodiments advantageously provide methods for WUS for a New Radio (NR) base station for network energy savings, as well as network nodes for implementing such methods.

Some embodiments provide a method that can activate the network node without additional connections when wireless devices (WDs) appear in the cell area that require support for initial access in the cell, for example. In some embodiments, one or more of the following are implemented: 1- A network node in idle mode, or a network node in the absence of established activity or WD presence in the cell area, switches off its transmitters since not sending periodic and non-periodic signals at all brings the highest energy efficiency gains. A receiver, preferably a low-power or wake-up receiver (LPR), remains activated to monitor the WUS from the WD. The low power receiver can continuously monitor pre-configured frequency resources, or it can monitor the pre-configured frequency resources at specified times (WUS opportunities).

2- The WUS opportunities can be pre-configured on time/frequency (T/F) resources. For example, in different time domain resources, different frequency domain resources are allocated as WUS opportunities. The WD can acquire the configurations of WUS opportunities from a same network node as was active earlier or from other active network nodes. Or the T/F resource configurations for the WD can be pre-configured in advance. Alternatively, the WD can assume an always on receiver, being configured with the frequency resources allocated for WUS opportunities.

3- The WUS can have different signatures, e.g., PRACH/preamble signature, On- Off Keying (OOK) signature, and Frequency-Shift Keying (FSK) signature.

4- Upon detection of a WUS from a WD, the network node main transceivers (in cases of LPR), and functionality related to transmission of the periodic and nonperiodic signals and reception of potential WD random access attempts, are reactivated.

Completely switching off the network node's transmitters can avoid transmitting periodic and non-periodic signals to save energy. Also, the network node can switch off some system components, such as some components of active array units (A AU) and baseband units (BBU) so that network energy efficiency can be further optimized. At the same time, once the network node receives the WUS, the network node may immediately exit a sleep state and starts to transmit periodic and non-periodic signals to provide low-latency services to WDs. Some embodiments improve energy efficiency and provide robust and responsive network performance, simultaneously.

Some embodiments provide wake up signals (WUS) for a New Radio (NR) base station to achieve network energy savings. In one aspect, a low power wakeup receiver (LPR) is implemented in the network specialized for WUS reception. During sleep time, the network node’s main receiver is in a sleep state and the BBU parts typically used for processing UL PRACH for initial access are also put to sleep. The LPR, based on WUS detection, wakes up the main receiver and the BBU.

Referring now to the drawing figures, in which like elements are referred to by like reference numerals, there is shown in FIG. 1 a schematic diagram of a communication system 10, according to an embodiment, such as a 3 GPP -type cellular network that may support standards such as LTE and/or NR (5G), which comprises an access network 12, such as a radio access network, and a core network 14. The access network 12 comprises a plurality of network nodes 16a, 16b, 16c (referred to collectively as network nodes 16), such as NBs, eNBs or other types of wireless access points, each defining a corresponding coverage area 18a, 18b, 18c (referred to collectively as coverage areas 18). Each network node 16a, 16b, 16c is connectable to the core network 14 over a wired or wireless connection 20. A first wireless device (WD) 22a located in coverage area 18a is configured to wirelessly connect to, or be paged by, the corresponding network node 16a. A second WD 22b in coverage area 18b is wirelessly connectable to the corresponding network node 16b. While a plurality of WDs 22a, 22b (collectively referred to as wireless devices 22) are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole WD is in the coverage area or where a sole WD is connecting to the corresponding network node 16. Note that although only two WDs 22 and three network nodes 16 are shown for convenience, the communication system may include many more WDs 22 and network nodes 16.

Also, it is contemplated that a WD 22 can be in simultaneous communication and/or configured to separately communicate with more than one network node 16 and more than one type of network node 16. For example, a WD 22 can have dual connectivity with a network node 16 that supports LTE and the same or a different network node 16 that supports NR. As an example, WD 22 can be in communication with an eNB for LTEZE-UTRAN and a network node for NR/NG-RAN.

The communication system 10 may itself be connected to a host computer 24, which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server or as processing resources in a server farm. The host computer 24 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. The connections 26, 28 between the communication system 10 and the host computer 24 may extend directly from the core network 14 to the host computer 24 or may extend via an optional intermediate network 30. The intermediate network 30 may be one of, or a combination of more than one of, a public, private or hosted network. The intermediate network 30, if any, may be a backbone network or the Internet. In some embodiments, the intermediate network 30 may comprise two or more sub-networks (not shown).

The communication system of FIG. 1 as a whole enables connectivity between one of the connected WDs 22a, 22b and the host computer 24. The connectivity may be described as an over-the-top (OTT) connection. The host computer 24 and the connected WDs 22a, 22b are configured to communicate data and/or signaling via the OTT connection, using the access network 12, the core network 14, any intermediate network 30 and possible further infrastructure (not shown) as intermediaries. The OTT connection may be transparent in the sense that at least some of the participating communication devices through which the OTT connection passes are unaware of routing of uplink and downlink communications. For example, a network node 16 may not or need not be informed about the past routing of an incoming downlink communication with data originating from a host computer 24 to be forwarded (e.g., handed over) to a connected WD 22a. Similarly, the network node 16 need not be aware of the future routing of an outgoing uplink communication originating from the WD 22a towards the host computer 24.

A network node 16 may be configured to include a wake-up receiver (WUR) 32 which is configured to listen for a wake up signal (WUS) from a WD, the WUR configured to consume less power than a receiver of the radio interface configured to receive additional signals.

Example implementations, in accordance with an embodiment, of the WD 22, network node 16 and host computer 24 discussed in the preceding paragraphs will now be described with reference to FIG. 2. In a communication system 10, a host computer 24 comprises hardware (HW) 38 including a communication interface 40 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system 10. The host computer 24 further comprises processing circuitry 42, which may have storage and/or processing capabilities. The processing circuitry 42 may include a processor 44 and memory 46. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 42 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 44 may be configured to access (e.g., write to and/or read from) memory 46, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read- Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Processing circuitry 42 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by host computer 24. Processor 44 corresponds to one or more processors 44 for performing host computer 24 functions described herein. The host computer 24 includes memory 46 that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 48 and/or the host application 50 may include instructions that, when executed by the processor 44 and/or processing circuitry 42, causes the processor 44 and/or processing circuitry 42 to perform the processes described herein with respect to host computer 24. The instructions may be software associated with the host computer 24.

The software 48 may be executable by the processing circuitry 42. The software 48 includes a host application 50. The host application 50 may be operable to provide a service to a remote user, such as a WD 22 connecting via an OTT connection 52 terminating at the WD 22 and the host computer 24. In providing the service to the remote user, the host application 50 may provide user data which is transmitted using the OTT connection 52. The “user data” may be data and information described herein as implementing the described functionality. In one embodiment, the host computer 24 may be configured for providing control and functionality to a service provider and may be operated by the service provider or on behalf of the service provider. The processing circuitry 42 of the host computer 24 may enable the host computer 24 to observe, monitor, control, transmit to and/or receive from the network node 16 and or the wireless device 22.

The communication system 10 further includes a network node 16 including hardware 58 enabling it to communicate with the host computer 24 and with the WD 22. The hardware 58 may include a communication interface 60 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 10, as well as a radio interface 62 for setting up and maintaining at least a wireless connection 64 with a WD 22 located in a coverage area 18 served by the network node 16. The radio interface 62 may be formed as or may include, for example, one or more RF transmitters 62-A, one or more RF receivers 62-B. The communication interface 60 may be configured to facilitate a connection 66 to the host computer 24. The connection 66 may be direct or it may pass through a core network 14 of the communication system 10 and/or through one or more intermediate networks 30 outside the communication system 10.

In the embodiment shown, the hardware 58 of the network node 16 further includes processing circuitry 68. The processing circuitry 68 may include a processor 70 and a memory 72. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 68 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 70 may be configured to access (e.g., write to and/or read from) the memory 72, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Thus, the network node 16 further has software 74 stored internally in, for example, memory 72, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the network node 16 via an external connection. The software 74 may be executable by the processing circuitry 68. The processing circuitry 68 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by network node 16. Processor 70 corresponds to one or more processors 70 for performing network node 16 functions described herein. The memory 72 is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 74 may include instructions that, when executed by the processor 70 and/or processing circuitry 68, causes the processor 70 and/or processing circuitry 68 to perform the processes described herein with respect to network node 16. For example, processing circuitry 68 of the network node 16 may include a WUR 32 which is configured to listen for a wake up signal, WUS, from a WD 22, the WUR configured to consume less power than a receiver of the radio interface configured to receive additional signals

The communication system 10 further includes the WD 22 already referred to. The WD 22 may have hardware 80 that may include a radio interface 82 configured to set up and maintain a wireless connection 64 with a network node 16 serving a coverage area 18 in which the WD 22 is currently located. The radio interface 82 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers.

The hardware 80 of the WD 22 further includes processing circuitry 84. The processing circuitry 84 may include a processor 86 and memory 88. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 84 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 86 may be configured to access (e.g., write to and/or read from) memory 88, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Thus, the WD 22 may further comprise software 90, which is stored in, for example, memory 88 at the WD 22, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the WD 22. The software 90 may be executable by the processing circuitry 84. The software 90 may include a client application 92. The client application 92 may be operable to provide a service to a human or non-human user via the WD 22, with the support of the host computer 24. In the host computer 24, an executing host application 50 may communicate with the executing client application 92 via the OTT connection 52 terminating at the WD 22 and the host computer 24. In providing the service to the user, the client application 92 may receive request data from the host application 50 and provide user data in response to the request data. The OTT connection 52 may transfer both the request data and the user data. The client application 92 may interact with the user to generate the user data that it provides.

The processing circuitry 84 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by WD 22. The processor 86 corresponds to one or more processors 86 for performing WD 22 functions described herein. The WD 22 includes memory 88 that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 90 and/or the client application 92 may include instructions that, when executed by the processor 86 and/or processing circuitry 84, causes the processor 86 and/or processing circuitry 84 to perform the processes described herein with respect to WD 22.

In some embodiments, the inner workings of the network node 16, WD 22, and host computer 24 may be as shown in FIG. 2 and independently, the surrounding network topology may be that of FIG. 1.

In FIG. 2, the OTT connection 52 has been drawn abstractly to illustrate the communication between the host computer 24 and the wireless device 22 via the network node 16, without explicit reference to any intermediary devices and the precise routing of messages via these devices. Network infrastructure may determine the routing, which it may be configured to hide from the WD 22 or from the service provider operating the host computer 24, or both. While the OTT connection 52 is active, the network infrastructure may further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network). The wireless connection 64 between the WD 22 and the network node 16 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the WD 22 using the OTT connection 52, in which the wireless connection 64 may form the last segment. More precisely, the teachings of some of these embodiments may improve the data rate, latency, and/or power consumption and thereby provide benefits such as reduced user waiting time, relaxed restriction on file size, better responsiveness, extended battery lifetime, etc.

In some embodiments, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 52 between the host computer 24 and WD 22, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection 52 may be implemented in the software 48 of the host computer 24 or in the software 90 of the WD 22, or both. In embodiments, sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection 52 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software 48, 90 may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 52 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect the network node 16, and it may be unknown or imperceptible to the network node 16. Some such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary WD signaling facilitating the host computer’s 24 measurements of throughput, propagation times, latency and the like. In some embodiments, the measurements may be implemented in that the software 48, 90 causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 52 while it monitors propagation times, errors, etc.

Thus, in some embodiments, the host computer 24 includes processing circuitry 42 configured to provide user data and a communication interface 40 that is configured to forward the user data to a cellular network for transmission to the WD 22. In some embodiments, the cellular network also includes the network node 16 with a radio interface 62. In some embodiments, the network node 16 is configured to, and/or the network node’s 16 processing circuitry 68 is configured to perform the functions and/or methods described herein for preparing/initiating/maintaining/supporting/ending a transmission to the WD 22, and/or preparing/terminating/maintaining/supporting/ending in receipt of a transmission from the WD 22.

In some embodiments, the host computer 24 includes processing circuitry 42 and a communication interface 40 that is configured to a communication interface 40 configured to receive user data originating from a transmission from a WD 22 to a network node 16. In some embodiments, the WD 22 is configured to, and/or comprises a radio interface 82 and/or processing circuitry 84 configured to perform the functions and/or methods described herein for preparing/initiating/maintaining/supporting/ending a transmission to the network node 16, and/or preparing/terminating/maintaining/supporting/ending in receipt of a transmission from the network node 16.

Although FIGS. 1 and 2 show various “units” such as the WUR unit 32 as being within a respective radio interface 62, it is contemplated that this unit may be implemented such that a portion of the unit is stored in a corresponding memory within the radio interface 62. In other words, the units may be implemented in hardware or in a combination of hardware and software within the processing circuitry.

FIG. 3 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIGS. 1 and 2, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIG. 2. In a first step of the method, the host computer 24 provides user data (Block SI 00). In an optional substep of the first step, the host computer 24 provides the user data by executing a host application, such as, for example, the host application 50 (Block SI 02). In a second step, the host computer 24 initiates a transmission carrying the user data to the WD 22 (Block SI 04). In an optional third step, the network node 16 transmits to the WD 22 the user data which was carried in the transmission that the host computer 24 initiated, in accordance with the teachings of the embodiments described throughout this disclosure (Block SI 06). In an optional fourth step, the WD 22 executes a client application, such as, for example, the client application 92, associated with the host application 50 executed by the host computer 24 (Block SI 08).

FIG. 4 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIG. 1, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIGS. 1 and 2. In a first step of the method, the host computer 24 provides user data (Block SI 10). In an optional substep (not shown) the host computer 24 provides the user data by executing a host application, such as, for example, the host application 50. In a second step, the host computer 24 initiates a transmission carrying the user data to the WD 22 (Block SI 12). The transmission may pass via the network node 16, in accordance with the teachings of the embodiments described throughout this disclosure. In an optional third step, the WD 22 receives the user data carried in the transmission (Block SI 14).

FIG. 5 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIG. 1, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIGS. 1 and 2. In an optional first step of the method, the WD 22 receives input data provided by the host computer 24 (Block SI 16). In an optional substep of the first step, the WD 22 executes the client application 92, which provides the user data in reaction to the received input data provided by the host computer 24 (Block SI 18). Additionally or alternatively, in an optional second step, the WD 22 provides user data (Block S120). In an optional substep of the second step, the WD provides the user data by executing a client application, such as, for example, client application 92 (Block S122). In providing the user data, the executed client application 92 may further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the WD 22 may initiate, in an optional third substep, transmission of the user data to the host computer 24 (Block S124). In a fourth step of the method, the host computer 24 receives the user data transmitted from the WD 22, in accordance with the teachings of the embodiments described throughout this disclosure (Block S126).

FIG. 6 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIG. 1, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIGS. 1 and 2. In an optional first step of the method, in accordance with the teachings of the embodiments described throughout this disclosure, the network node 16 receives user data from the WD 22 (Block S128). In an optional second step, the network node 16 initiates transmission of the received user data to the host computer 24 (Block SI 30). In a third step, the host computer 24 receives the user data carried in the transmission initiated by the network node 16 (Block SI 32).

FIG. 7 is a flowchart of an example process in a network node 16 for wake up signals (WUS) for network energy savings. One or more blocks described herein may be performed by one or more elements of network node 16 such as by one or more of processing circuitry 68, processor 70, radio interface 62 (including the WUR 32) and/or communication interface 60. Network node 16 such as via processing circuitry 68 and/or processor 70 and/or radio interface 62 and/or communication interface 60 is configured to deactivate at least one transmitter of the radio interface allocated to serve a cell currently serving no WDs (Block SI 34). The process also includes listening via a wake up receiver, WUR, for a wake up signal, WUS, from a WD, the WUR configured to consume less power than a receiver of the radio interface configured to receive additional signals (Block S136).

Having described the general process flow of arrangements of the disclosure and having provided examples of hardware and software arrangements for implementing the processes and functions of the disclosure, the sections below provide details and examples of arrangements for wake up signals (WUS) for a base station (such as NR base stations) for network energy savings.

Some embodiments include methods for reducing network energy consumption caused by the transmitters 62-A for broadcasting periodic and non- periodic signals e.g., for the sake of WD 22 random initial access. More specifically, the network node 16 in idle mode switches off its transmitters 62-A and a receiver of the network node 16 remains on, or periodically on, to monitor for a WUS from the WD 22. The receiver used for monitoring for the WUS may for example be a low power receiver such as the WUR 32, and the network node 16 may also turn off the main receiver 62-B. For example, the lower power receiver (WUR 32) may use fewer (time /frequency) T/F resources and may be able to detect specific signatures with lower hardware (HW) complexity with respect to the full receiver 62-B. WUS reception may then trigger a full transceiver wake-up. When the main receiver 62-B and transmitter chains are turned off, the associated baseband entities (HW blocks such as digital signal processors (DSPs), central processing units (CPUs), etc.) that typically are involved in processing data from the transceiver chains (e.g., for transmitting broadcast, receiving PRACH, etc.) are also turned off. As used herein, the term “deep sleep” may be used to denote the energy saving state explained herein.

A comparison of the time and frequency domain resources is depicted in the example of FIG. 8, in which both a conventional network node 16 configuration and a WUS-based network node 16 configuration are visualized. The conventional network node 16 configuration in idle mode, which here refers to network node 16 operation when there are no connected-mode WDs 22 in the cell, may include multiple RACH occasions densely provided both in frequency and time. Such configuration is suitable for handling many uplink (UL) requests from different WDs 22 with minimal response delay. As an example, 4 PRACH resources may be multiplexed in frequency and every 20ms in time. Such configuration comes at the cost of the network node 16 periodically transmitting SSB and System information (SI) over a wider bandwidth and listening to PRACH. The network node 16 inevitably consumes energy periodically even if there are no WDs 22 present in a cell. In such a configuration, due to the 20ms periodicity of PRACH occasions, the network node 16 is left with limited sleeping opportunity in the gaps, even though no WD 22 is present in the cell. For example, in one implementation, the network may be able to apply micro-transmit (TX) sleep, which means to only turn off the transmitter 62-A, while the digital front end and baseband component of the transmitters 62-A do not sleep nor stay dormant due to the transition time. In contrast, the WUS-based network node 16 configuration in idle mode omits processing and transmission of all periodic and non-periodic signals, in some embodiments. The WUS-based network node 16 provides resources in time and frequency at the WURs receivers 32 to monitor WUS from the WDs 22. Depending on the network node 16 sleep state and WUS signal design, the time resource may be continuous and infinite while the network node 16 is listening for the WUS. For example, if the network node 16 has completely turned off its transmission, there is no synchronization source/possibility for a WD 22 entering the area, so the network node 16 WUS receiver (WUR) 32 may remain on to constantly monitor for the WUS. As such, the WD 22 has the freedom to transmit the WUS at any point in time. As an example, the WUR receiver 32 of the network node 16 continuously monitors the arrival of the WUS on 3 different frequency domain resources. Such configuration is more suitable for deployments at locations with low traffic, or small cells only handling a few WDs 22, during certain times of day, for example, or for occasions during which only a few WDs 22 access the cell, or alternately, when many WDs 22 are accessing the cell but the WDs 22 are of such type that can tolerate long delays for accessing the cell (e.g., delay tolerant sensors). This WUS based network node 16 configuration helps the network node 16 to conserve energy as the network node 16 may only need to have its transmitters 62-A off and a low power receiver on over a narrower bandwidth. Only two WUS monitoring mechanisms (continuous and non- continuous WUS opportunities) and limited number of types of WUS are exemplified for the sake of simplicity. There may however be multiple configurations implemented in a network where different WUS monitoring mechanisms can be used alone or in combination, and different WUS types, e.g., PRACH preamble, OOK signature, and FSK signature, can also be used alone or in combination.

Throughout the remainder of this disclosure, it is noted that frequency multiplexing not exemplified in some embodiments for the sake of simplicity may nevertheless be implemented in some embodiments. However, in some embodiments, when the time domain resource is allocated continuously or discontinuously, the frequency multiplexing or varying frequency allocation for the WUS (or frequencyhopping) can also be applied at any time. Frequency allocation of WUS

The WUR receiver 32 of a network node 16 monitors the arrival of the WUS from the WD 22. Upon WUS reception, for example, if a PRACH-based WUS is received, the network node 16 turns on its transmitters 62-A and starts to send SSB and SI and listen to PRACH in a regular way.

FIG. 9 illustrates examples of WUS-based network node configurations.

In one embodiment, the WUR receiver 32 continuously monitors the arrival of WUS in the time domain while the frequency domain allocation is fixed as shown in the (a) part of FIG. 9. This implies that there is at least one fixed frequency resource allocated to WUS opportunities at any moment. Although only one frequency resource is shown in the (a) part of FIG. 9, more than one frequency resource can be allocated to WUS opportunities. A WUS can be sent by the WD 22 and received by the network node 16 at any time and frequency resource within WUS occasions. The frequency allocation can be pre-configured, e.g., predetermined as part of standards, or the frequency allocation may be conveyed to the WD 22 either from another network node 16, or the current network node 16 when it was on, or through a newly designed SSB potentially with a longer periodicity, and narrower T/F allocation than the conventional SSB.

In one embodiment, the WUR receiver 32 continuously monitors the arrival of the WUS in the time domain while the frequency domain allocation changes with time as shown in the (b) part of FIG. 9, which implies that there is at least one timevarying frequency resource allocated to the WUS occasions at any moment. This configuration is suitable for scenarios where the network node 16 first monitors the WUS occasions in a wide frequency band for a certain time duration. If the WUS is not received, the network node 16 allocates less frequency band to monitoring the WUS to save energy. If the WUS is still not received, the network node 16 may allocate much less frequency band to monitoring the WUS to save more energy or keep the frequency allocation unchanged. The frequency allocation can be conveyed to the WD 22 either from another network node 16, or the current network node 16 when it was on, or through a newly designed SSB potentially with a longer periodicity, and narrower T/F allocation than the conventional SSB. In one embodiment, the WUR receiver 32 continuously monitors the arrival of a WUS in the time domain while the frequency coverage in different WUS opportunities is different as shown in the (c) part of FIG. 9. This implies that there is at least one frequency resource allocated to WUS opportunities at any moment. For example, the frequency coverage of each WUS opportunity may or may not have overlaps. The bandwidth of each WUS opportunity can be the same or different.

In one embodiment, the WUR. receiver 32 continuously monitors the arrival of WUS in the time domain while the frequency domain allocation is based on network traffic forecasts and experience or other mechanisms, as shown in the (d) part of FIG. 9. This implies that there is at least one frequency resource allocated to WUS opportunities at any moment. For example, if the number of WDs 22 increases in a certain period, the network node 16 may increase the frequency resources allocated to a WUS opportunity in that period. If the number of WDs 22 decreases significantly in another period, the network node 16 will reduce the frequency resources allocated to a WUS opportunity in that period. The frequency allocation can be conveyed to the WD 22 either from another network node 16, or the current network node 16 when it was on, or through a newly designed SSB potentially with a longer periodicity, and narrower T/F allocation than the regular SSB.

When reserving resources for WUSs, this may be done in a narrowfrequency manner to avoid using too much of the system bandwidth (BW). In one embodiment, the WUS is defined in a low numerology, e.g., using f_c= \ 5kHz even though the system currently operates on _c=30 kHz. This could be done by changing the bandwidth part (BWP) to a BWP with a certain numerology.

While the reservation of resources is typically done over a full PRB, the actual WUS transmission may not need the bit load corresponding to the full range of reserved resources. The subcarriers close to the edges can then be used as guard bands to provide robustness from inaccurate frequency synchronization due to, for example, clock drifts in a non-connected mode

Temporal allocation of WUS

FIG. 10 illustrates more examples of WUS-based network node configurations. In one embodiment, the WUR receiver 32 discontinuously monitors the arrival of the WUS in the time domain, and intervals between WUS opportunities are equal as shown in the (a) part of FIG. 10. This implies that there is no frequency resource allocated to WUS opportunities at certain moments. A WUS can be sent by the WD 22 and received by the network node 16 at any time and frequency resource within WUS opportunities. The bandwidth of WUS opportunities can be the same or different. The frequency coverage of each WUS opportunity may or may not be the same. In one typical example, the duration of each WUS opportunity may be the same. However, as shown in the (a) part of FIG. 10, the duration of each WUS opportunity may also be set differently.

In one embodiment, the WUR receiver 32 discontinuously monitors the arrival of a WUS in the time domain when intervals between WUS opportunities are unequal as shown in the (b) part of FIG. 10. It implies that there is no frequency resource allocated to WUS opportunities at certain moments. The bandwidth of WUS opportunities can be the same or different. The frequency coverage of each WUS opportunity may or may not be the same. In one typical example, the duration of each WUS opportunity may be the same. However, as shown in the (b) part of Figure 10, the duration of each WUS opportunity may also be set differently.

In one embodiment, the network node 16 can switch between continuous WUS opportunities and discontinuous WUS opportunities based on network traffic forecasts and experience or other mechanisms, as shown in the (c) part of FIG 10. For example, if the number of WDs 22 is low in a certain period, the network node 16 may adopt discontinuous WUS opportunities to save more energy. If the number of WDs 22 increases significantly in another period, the network node 16 adopts continuous WUS opportunities to prioritize access performance. In a more specific example, based on the time of the day, e.g., the network may adopt discontinuous WUS opportunities during the night and adopt continuous WUS opportunities during the day.

In one embodiment, the WUR receiver 32 reuses PRACH occasions for WUS opportunities as shown in the (d) part of FIG. 10. This implies that there is no frequency resource allocated to WUS opportunities at certain moments. PRACH occasions may be pre-configured or indicated to the WD 22 by higher network layers, the network node 16 when last on, or other network nodes 16. The frequency multiplexing, RACH-configuration period and other PRACH parameters may be determined by PRACH configurations which are pre-configured or indicated to the WD 22.

When the WUS opportunities are non-contiguous in time, there is a risk that after a timing drift in a non-connected mode, the WUS transmissions occur outside the allocated region, and would cause interference. In one embodiment, the actual WUS transmissions are shorter in time than the allocated time resources, where the silent periods in beginning and/or end serve as guard periods.

In another embodiment, a single WUS transmission is much shorter in time than the allocated time resource, and several WUS transmissions within the same WUS opportunity may be used by the WUR receiver 32 to increase the signal-to- noise ratio (SNR) and increase the reception performance of a radio of less than full capability such as a low-power receiver.

In one embodiment, the WUS transmissions from several WUS opportunities may be combined to increase WUR receiver 32 sensitivity. Post-processing of received signals is relatively cheap in comparison to the power consumption of the main receiver 62-B.

The configurations above in which the frequency or time allocation change call for a synchronization between the WD 22 and network node 16, or the WD 22 may transmit a WUS in the possible T/F allocations randomly until the WUS is received by the network node 16. In both cases, the configuration can be provided to the WD 22 via pre-configuration, or through another network node 16, or the same network node 16 when it was on or a newly designed SSB different from a conventional SSB. In this case, when the WD 22 is supposed to be synchronized with the network node 16, a lightweight synchronization signal mechanism, e.g., a lightweight primary synchronization signal (PSS) can be transmitted by the network on a periodic basis, for example, so that the WD 22 may remain in synchronization with the network node 16.

WD 22 determination and/or signaling of WUS opportunities In one group of embodiments, the WUS transmission framework is set up to support WDs 22 with no existing network connection, e.g., WDs 22 wishing to perform initial access towards the network.

The T/F allocation of a WUS may be standardized, e.g., a fixed frequency and time pattern may be defined per band or part of band supported by multiple operators. The frequency location may be fixed in this option, since tentative WUS transmission in many candidate locations may cause excessive interference.

Alternatively, the WD 22 may obtain network-specific settings from operator information stored on the subscriber identity module (SIM) card, or via over-the-top mechanisms using other connections/channels. Note that these configurations of WUSs may at any time change upon a connection to the network. For example, after an initial or subsequent connection, a network node 16 (e.g., network node, Core network node such as access and mobility management function (AMF), etc.) may provide at least one other WUS configuration to the WD 22. Such WUS configuration(s) may also be accompanied with:

• WUS signal characteristics, e.g., whether WUS is PRACH preamblebased and in such cases the preamble configuration, or whether a specific other type of sequence is used;

• WUS time and frequency resources;

• WUS transmission and response reception pattern, i.e., the steps of: o up to how many times, at what rate (i.e., for how long the WD

22 should await network node 16 response before another WUS attempt), and power level in each step the WD 22 transmits WUS; o step retrial configuration, e.g., the previous step may only be carried out once per minute; and/or

• WUS validity area, e.g., a geographical area in which WD 22 may use WUSs.

The WUS validity area configuration may inform the WD 22 that it is only valid within a certain geographical area, e.g., within a country. From the WD 22 point of view the area it is currently in may be determined by any means. For example if the WD 22 is not equipped with or may not choose to use a positioning system (such as the Global Positioning System (GPS)), the WD 22 may read the mobile country code (MCC) of broadcast public land mobile networks (PLMNs) of other operators (of any other technology such as LTE, Global System for Mobile Communications (GSM), etc.). This may be done in case of overlapping or recently-read MCCs from those operator networks.

In one embodiment, the WD 22 may be provided with a set of WUS configurations applicable to different areas. For example, when in a home country, a certain WUS configuration applies, whereas when roaming into another country or operator network, another WUS configuration is applicable.

In one embodiment, a WD 22 performing initial access will perform a conventional frequency scan in its supported bands. If no accessible cells are found, the WD 22 may use the operator information included on the SIM card to determine a WUS configuration and perform a WUS-based procedure described herein to turn on SBB and other signals. After that, the WD 22 may repeat the conventional cell scan and initial access procedure in one or more bands and/or carriers of a carrier subset which may be obtained from the operator.

In another group of embodiments, the WUS framework relies on and presumes an existing network connection, e.g., via another cell or another frequency layer of a same or different radio access technology (RAT). The WUS configuration information may then be provided via the other connection.

WUS signal design and transmission by WD 22

The WUS signal design may be selected to allow detection with a LPR, which is also called a WUR (Wake-Up Receiver) 32, and to provide robust UL transmission and reception in the absence of tight T/F synchronization. Some example signal types include:

• PRACH preamble-like design;

• OOK signature;

• FSK signature;

• OFDM or other conventional signal (conventional referring to signal type used in the Radio Access Technology (RAT) used by the network node 16): o OFDM subcarrier spacing for the WUS may be increased in order to decrease sensitivity to frequency errors; and/or • Others.

The signal design may be selected to allow reliable reception with the WUR that is constrained to operate at a predetermined power level, considering the number of supported receiver (RX) branches, radio frequency (RF) front end sensitivity and linearity, etc. In one approach, the WUR constraints, WD 22 power budget, and propagation conditions in the cell are used to determine the WUS signal design and current configuration, preferably including:

• Signal type (determining the required receiver processing);

• BW and time duration of the transmitted signal (determining the WUR energy transmitted by the WD 22);

• Frequency allocation, and optionally time allocation (determining the reception window in the WUR); and/or

• WUS configuration aspects like sequences, shifts, search spaces, payload parameters, etc., (determining required receiver configuration and detection/decoding configuration).

In one group of embodiments, the WUS may be designed as an indicator that triggers the network node 16 to resume SSB and SI transmission.

In another group of embodiments, the WUS may additionally be designed to convey WD 22 identity or WD 22 type (e.g., RedCap, evolved mobile broadband (eMBB)), or access type (e.g., whether delay tolerant or sensitive) or resources to transmit information to the network. Based on such indications, the network may adapt how fast it goes back to a deep sleep state after the communication with the WD 22. E.g., if a delay sensitive WD 22 has transmitted the WUS, the network may not go back to a deep sleep state as fast as it would have done otherwise.

T/F allocation by the network may be wider or longer than the transmitted signal, to provide guard bands or periods and margins for T/F synchronization errors.

In one aspect, the WD 22 may during its frequency scan, tune its oscillator (time/frequency synchronization) from other overlapping RATs. For example, during the scan, the WD 22 may acquire synchronization from another operator’s broadcast signal or channels including when the signal or channel is from another RAT. In one embodiment, in the absence of external frequency references, the WD 22 may rely on the default open-loop accuracy of its local oscillator, ensuring sufficient accuracy by design.

In one aspect, the information about a WUS may be broadcast in another overlapping RATs system information. For example, assume a scenario in which an NR-capable WD 22 does not find an NR cell to camp on because the network node 16 that would have otherwise provided such coverage is in deep sleep. Assume further that this WD 22 camps on an overlapping LTE cell where the cell advertises in its broadcast configuration that there exists overlapping NR coverage that may be activated via a WUS. This information may either be an indicator or include a WUS configuration. Hence, the WD 22 can invoke the sleeping network node 16 and enjoy NR coverage/service as a result.

WUS reception at network node 16

In one embodiment, the network node 16 utilizes a low-power receiver (LPR), or a wake-up receiver 32, for WUS monitoring. The WUR may be designed as a separate HW block, distinct from the full network node radio interface 62. The sensitivity and other fidelity parameters for the WUR RF solution may be limited to quality required to reliably receive WUS from cell edge regions.

An LPR has a receiver structure that may typically consume significantly less power than the full network node 16 receiver 62-B. In some implementations, the WUR power consumption may be significantly lower, e.g., an order of magnitude lower, than the network node 16 deep sleep power consumption of the full transceiver. Thus, the WUR may run continuously without a significant energy consumption impact. As an example, if the network node 16 deep sleep power is 50W, the LPR/WUR may operate at 2-5W.

Alternatively, a criterion may be formed with reference to sleep level, e.g., the deep sleep plus WUR mode should provide significant power saving. For example, if the light sleep level is 250W and the deep sleep level is 50 W, it may be considered beneficial to allow up to 50W WUR consumption, still saving 60% of power compared to remaining in light sleep. When the WUR power consumption is similar or exceeds the deep sleep power or other criterion, the WUR may be gated or configured to run discontinuously, depending on the WUS time resource allocation. In one embodiment, the WUR performs WUS detection in the form of known sequence detection using a correlation receiver in the time or frequency domain. The signal may be correlated with multiple versions or copies of the reference sequence, corresponding to possible locations in frequency or time. If, for some hypothesis, a correlation result exceeding a threshold is observed, the WUS is considered as detected and the full receiver 62-B is activated.

In another embodiment, the WUR may perform WUS reception using a conventional reception process where the received signal is sampled, and tentative demodulation and decoding is performed for several frequency and time shifts of the received signal. If a WUS signal is successfully decoded, the full receiver 62-B is activated.

In receiving the WUS from the WD 22, a predefined missed detection rate (MDR) threshold may also be defined (e.g., by the standard). For example, the MDR of the WUS can be defined to be 1% (like PRACH), i.e., the network may need to be able to detect, at least, 99% of the WUS sent by the WD 22. Note that the value of the MDR may also be tied to the channel quality (e.g., signal to interference plus noise ratio (SINR) value or value range) between the WD 22 and the network. Alternatively, a smaller MDR may also be used when the WUS design is compact, carrying only a small amount of information in the signal.

Some embodiments may include one or more of the following.

Embodiment (Emb) 1) A method in a network in which a network node 16 in idle mode, or in the absence of established activity or WD 22 presence in the cell area, switches off its transmitters 62-A and no periodic and non-periodic signals are sent, e.g., SSB, SIB. Also, the network node 16 receiver 62-B activity related to regular WD 22 Random Access/Initial Access preamble decoding is suspended/put to sleep.

Emb 2) Emb 1 and the receiver(s) of this network node 16, e.g., a low power receiver monitors WUS from WD 22 through one or more combinations of the following mechanisms: a) The receivers are always on to monitor the WUS from WD 22. b) The receivers monitor the WUS from WD 22 at specified time (WUS opportunities). c) a) + b) the receivers monitor the WUS from WD 22 on fixed frequency resources, or on variable frequency resources.

Emb 3) Any of Emb s 1 and 2 and the network node 16 receives a WUS. The WUS maybe a PRACH/preamble signature, an OOK signature, a FSK signature or any other pre-configured signals.

Emb 4) Any of Emb s 1 to 3 and upon detection of WUS, the network node 16 then starts to transmit periodic and non-periodic signals and prepares for PRACH preamble reception from the first WD 22 and others. The network node 16 may in such case be equipped with a low power receiver (LPR) in which case the LPR wakes up the main transceiver based on WUS detection.

Emb 5) Any of Emb s 1 to 4 and if the last connected WD 22 leaves the coverage area of current network node 16, the current network node 16 immediately switches off its transmitters 62-A, or turns off its transmitters 62-A after a period, and starts to monitor WUS from WD 22.

Emb 6) A method in a WD 22, where the WD 22 follows a first action, and if the first action is not viable, the WD 22 applies the second action. The first action is the current initial access procedure, i.e., finding SIB, transmitting PRACH, and then follow the initial access messages. The second action is the WUS method for network node 16.

Emb 7) Any of Emb 6 and the WD 22 starts with the second action, e.g., if the WD 22 believes that this cell is typically OFF.

Emb 8) Any of Embs 6 and 7 and the WD 22 become aware that this cell is a WUS enabled cell, e.g., through a SSB with long periodicity, e.g., every 1 second. This SSB can be designed differently from a regular cell SSB, e.g., of narrower BW, and lower number of contents.

Emb 9) Any of Embs 1-8 and the WD 22 is configured with WUS configuration, where the configuration may be preconfigured in the WD 22 (e.g., by the operator and stored in the WD 22 (e.g., on SIM CARD) or defined by the specifications) or provided by a network node 16 either during a past connection or read from broadcast channel in same or any past cell or from broadcast of another overlayed radio access technology (RAT) and include one or more combination of: a) WUS characteristics, e.g., whether WUS is PRACH preamble-based and in such case the preamble configuration, or whether a specific other type of sequence is used; b) WUS validity area. E.g., a geographical area in which WD 22 may use WUS c) WUS time and frequency resources; d) WUS transmission and response reception pattern, i.e., the steps of i. up to how many times, at what rate (i.e., for how long the WD 22 should await network node 16 response before another WUS attempt), and power level in each step the WD 22 transmits WUS; ii. step retrial configuration, e.g., the steps in i.) above may only be carried out once per minute, for example.

As will be appreciated by one of skill in the art, the concepts described herein may be embodied as a method, data processing system, computer program product and/or computer storage media storing an executable computer program. Accordingly, the concepts described herein may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects all generally referred to herein as a “circuit” or “module.” Any process, step, action and/or functionality described herein may be performed by, and/or associated to, a corresponding module, which may be implemented in software and/or firmware and/or hardware. Furthermore, the disclosure may take the form of a computer program product on a tangible computer usable storage medium having computer program code embodied in the medium that can be executed by a computer. Any suitable tangible computer readable medium may be utilized including hard disks, CD-ROMs, electronic storage devices, optical storage devices, or magnetic storage devices.

Some embodiments are described herein with reference to flowchart illustrations and/or block diagrams of methods, systems and computer program products. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer (to thereby create a special purpose computer), special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer readable memory or storage medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instruction means which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

It is to be understood that the functions/acts noted in the blocks may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows.

Computer program code for carrying out operations of the concepts described herein may be written in an object oriented programming language such as Python, Java® or C++. However, the computer program code for carrying out operations of the disclosure may also be written in conventional procedural programming languages, such as the "C" programming language. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer. In the latter scenario, the remote computer may be connected to the user's computer through a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, all embodiments can be combined in any way and/or combination, and the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the embodiments described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination.

Below is a list of example embodiments.

Embodiment Al . A network node configured to communicate with a wireless device, WD, the network node configured to, and/or comprising a radio interface and/or comprising processing circuitry configured to: deactivate at least one transmitter of the radio interface allocated to serve a cell currently serving no WDs; and listen via a wake up receiver, WUR, for a wake up signal, WUS, from a WD, the WUR configured to consume less power than a receiver of the radio interface configured to receive additional signals.

Embodiment A2. The network node of Embodiment Al, wherein the network node, radio interface and or processing circuitry are configured to deactivate at least one receiver other than the WUR.

Embodiment A3. The network node of any of Embodiments Al and A2, wherein the WUR is configured to listen for the WUS on a fraction of the time and frequency resources allocated to receiving the additional signals.

Embodiment A4. The network node of any of Embodiments A1-A3, wherein the WUR is configured to listen for the WUS on multiple frequency resources during at least one time interval.

Embodiment A5. The network node of any of Embodiments A1-A4, wherein a time and frequency resource allocation for listening for the WUS is indicated to the WD. Embodiment A6. The network node of any of Embodiments A1-A5, wherein the listening is selected as one of discontinuous and continuous.

Embodiment A7. The network node of Embodiment A6, wherein the selecting is based at least in part on at least one of traffic forecasts and actual traffic.

Embodiment A8. The network node of Embodiment A6, wherein the selecting is based at least in part on a comparison between a light sleep power level to a deep sleep power level.

Embodiment A9. The network node of any of Embodiments A1-A8, wherein the listening includes sequence detection by correlation.

Embodiment Bl. A method implemented in a network node, the method comprising: deactivating at least one transmitter of the radio interface allocated to serve a cell currently serving no WDs; and listening via a wake up receiver, WUR, for a wake up signal, WUS, from a WD, the WUR configured to consume less power than a receiver of the radio interface configured to receive additional signals.

Embodiment B2. The method of Embodiment Bl, further comprising deactivating at least one receiver other than the WUR.

Embodiment B3. The method of any of Embodiments Bl and B2, wherein the WUR is configured to listen for the WUS on a fraction of the time and frequency resources allocated to receiving the additional signals.

Embodiment B4. The method of any of Embodiments B1-B3, wherein the WUR is configured to listen for the WUS on multiple frequency resources during at least one time interval.

Embodiment B5. The method of any of Embodiments B1-B4, wherein a time and frequency resource allocation for listening for the WUS is indicated to the WD.

Embodiment B6. The method of any of Embodiments B1-B5, wherein the listening is selected as one of discontinuous and continuous.

Embodiment B7. The method of Embodiment B6, wherein the selecting is based at least in part on at least one of traffic forecasts and actual traffic. Embodiment B8. The method of Embodiment B6, wherein the selecting is based at least in part on a comparison between a light sleep power level to a deep sleep power level.

Embodiment B9. The method of any of Embodiments B1-B8, wherein the listening includes sequence detection by correlation.

It will be appreciated by persons skilled in the art that the embodiments described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings.

Claims

1. A method implemented in a network node (16), the method comprising: monitoring for receipt of a wake-up signal, WUS, from a wireless device (22); and performing at least one of the following three actions in response to receipt of the WUS: transmitting synchronization signal blocks, SSBs; transmitting system information; monitoring physical random access channel, PRACH, occasions for receipt of a PRACH preamble.

2. The method of claim 1, further comprising: activating a transmitter (62- A) and/or receiver (62-B) of the network node in response to receipt of the WUS.

3. The method of any of claims 1-2, further comprising: activating an advanced antenna unit, AAU, and/or a baseband unit, BBU, and/or a digital signal processor, DSP, and/or a central processing unit, CPU, in response to receipt of the WUS.

4. The method of any of claims 1-3, further comprising: transmitting a synchronization signal, prior to receipt of the WUS, for the wireless device to synchronize with the network node.

5. The method of any of claims 1-4, further comprising: transmitting a configuration to the wireless device prior to receipt of the WUS, the configuration including: a frequency allocation for the WUS; and/or a time allocation for the WUS; and/or signal characteristics of the WUS; and/or a validity area of the WUS.

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6. The method of claim 5, wherein the configuration is conveyed through a SSB with longer periodicity and/or narrower time/frequency allocation than a regular SSB.

7. The method of any of claims 1-6, wherein the WUS has:

PRACH preamble signature; or

On-Off Keying, OOK, signature; or

Frequency-Shift Keying, FSK, signature.

8. The method of any of claims 1-7, wherein the WUS is received at a PRACH occasion.

9. The method of any of claims 1-8, wherein the network node comprises a main receiver (62-B) and a wake-up receiver (32), WUR, with lower power consumption than the main receiver, wherein the WUS is received by the WUR, and wherein the main receiver is activated in response to receipt of the WUS.

10. The method of any of claims 1-9, wherein the monitoring for receipt of the WUS is performed while the network node is in an energy saving state.

11. The method of any of claims 1-10, wherein the monitoring: is performed continuously in a time domain; or is performed discontinuously in the time domain.

12. The method of any of claims 1-11, further comprising: prior to receiving the WUS, deactivating a transmitter (62-A) and/or receiver (62-B) of the network node in absence of wireless device presence in a cell area of a cell served by the network node.

13. The method of any of claims 1-12, wherein the monitoring includes sequence detection by correlation.

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14. The method of any of claims 1-13, wherein the monitoring is performed on multiple frequency resources during at least one time interval.

15. A network node (16) configured to communicate with a wireless device (22), the network node being configured to: monitor for receipt of a wake-up signal, WUS, from the wireless device; and perform at least one of the following three actions in response to receipt of the WUS: transmitting synchronization signal blocks, SSBs; transmitting system information; monitoring physical random access channel, PRACH, occasions for receipt of a PRACH preamble.

16. The network node of claim 15, configured to perform the method of any of claims 2-14.

17. A network node (16) configured to communicate with a wireless device (22), the network node comprising a radio interface (62) and processing circuitry (68) configured to: monitor for receipt of a wake-up signal, WUS, from the wireless device; and perform at least one of the following three actions in response to receipt of the WUS: transmitting synchronization signal blocks, SSBs; transmitting system information; monitoring physical random access channel, PRACH, occasions for receipt of a PRACH preamble.

18. The network node of claim 17, the radio interface and processing circuitry being configured to perform the method of any of claims 2-14.

19. A method implemented in a wireless device (22), the method comprising: transmitting a wake-up signal, WUS, to a network node (16); and performing at least one of the following three actions after transmission of the WUS: receiving a synchronization signal block, SSB, from the network node; receiving system information from the network node; transmitting a physical random access channel, PRACH, preamble to the network node.

20. The method of claim 19, wherein the WUS is transmitted for activating a transmitter (62- A) and/or receiver (62-B) of the network node.

21. The method of any of claims 19-20, wherein the WUS is transmitted for activating an advanced antenna unit, AAU, and/or a baseband unit, BBU, and/or a digital signal processor, DSP, and/or a central processing unit, CPU, of the network node.

22. The method of any of claims 19-21, further comprising: synchronizing, using a synchronization signal from the network node, before transmitting the WUS.

23. The method of any of claims 19-22, further comprising: receiving a configuration from the network node before transmitting the WUS, the configuration including: a frequency allocation for the WUS; and/or a time allocation for the WUS; and/or signal characteristics of the WUS; and/or a validity area of the WUS.

24. The method of claim 23, wherein the configuration is conveyed through a SSB with longer periodicity and/or narrower time/frequency allocation than a regular SSB.

25. The method of any of claims 19-24, wherein the WUS has: PRACH preamble signature; or

On-Off Keying, OOK, signature; or

Frequency-Shift Keying, FSK, signature.

26. The method of any of claims 19-25, wherein the WUS is transmitted at a PRACH occasion.

27. The method of any of claims 19-26, wherein the network node comprises a main receiver (62-B) and a wake-up receiver (32), WUR, with lower power consumption than the main receiver, wherein the WUS is transmitted to the network node for receipt by the WUR and for activating the main receiver of the network node.

28. The method of any of claims 19-27, wherein the WUS is transmitted to the network node while the network node is in an energy saving state.

29. The method of any of claims 19-28, wherein the WUS is transmitted in response to the wireless device detecting that a cell is WUS enabled.

30. The method of claim 29, wherein the wireless device detects that the cell is WUS enabled through reception of a SSB with longer periodicity and/or narrower bandwidth and/or less content than a regular SSB.

31. The method of any of claims 19-30, wherein the WUS is in accordance with a WUS configuration which is: preconfigured in the wireless device: or provided by a network node during a past connection; or read from a broadcast channel in the same cell or any past cell or from broadcast of another overlayed radio access technology, RAT.

32: A wireless device (22) configured to: transmit a wake-up signal, WUS, to a network node (16); and perform at least one of the following three actions after transmission of the WUS: receive a synchronization signal block, SSB, from the network node; receive system information from the network node; transmit a physical random access channel, PRACH, preamble to the network node.

33. The wireless device claim 32, configured to perform the method of any of claims 20-31.

34. A wireless device (22) comprising a radio interface (82) and processing circuitry (84) configured to: transmit a wake-up signal, WUS, to a network node (16); and perform at least one of the following three actions after transmission of the WUS: receive a synchronization signal block, SSB, from the network node; receive system information from the network node; transmit a physical random access channel, PRACH, preamble to the network node.

35. The wireless device of claim 34, the radio interface and processing circuitry being configured to perform the method of any of claims 20-31.

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