Method, communication device and infrastructure device

Abstract

A method of operating a communication device including a low-power receiver and a primary receiver is provided. The method comprises: determining whether the communication device is to monitor a first signal from a wireless communication network, where the first signal comprises an indication of timing information of the wireless communication network; if the communication device determines to monitor the first signal, receiving the first signal from the wireless communication network via the low-power receiver when the low-power receiver is in an on state and the primary receiver is in an off state; and synchronizing the communication device with the wireless communication network based on the timing information of the wireless communication network. Here, the power consumption of the low-power receiver when the low-power receiver is in the on-state is lower than the power consumption of the main receiver when the main receiver is in the on-state.

Description

Technical Field

[0001] The present disclosure relates to communication devices, infrastructure devices, and methods for more effectively saving power of communication devices in a wireless communication network.

[0002] This application claims the Paris Convention priority of European Patent Application No. EP22205667.3 filed on November 4, 2022, the content of which is incorporated herein by reference. Background Art

[0003] The "Background" description provided herein is for the purpose of presenting the context of the present disclosure generally. To the extent described in this background art section, the work of the currently named inventors and aspects of the description that may not be prior art at the time of filing are neither expressly nor implicitly regarded as prior art against the present invention.

[0004] Previous generations of mobile telecommunications systems (e.g., mobile telecommunications systems based on the UMTS and Long Term Evolution (LTE) architectures defined by 3GPP) have been able to support a wider range of services than the simple voice and messaging services provided by previous generations of mobile telecommunications systems. For example, through the improved radio interface and enhanced data rates provided by the LTE system, users are able to enjoy high data rate applications, such as mobile video streaming and mobile video conferencing, which were previously only available via fixed-line data connections. Therefore, there is a great demand for deploying such networks, and the coverage areas of these networks (i.e., the geographical locations where the network can be accessed) are expected to continue to increase rapidly.

[0005] It is expected that current and future wireless communication networks will routinely and effectively support communication with a wider range of devices than currently optimized systems support, where these devices are associated with a wider range of data service profiles and types. For example, future wireless communication networks are expected to effectively support communication with devices including reduced complexity devices, machine type communication (MTC) devices, high-resolution video displays, virtual reality headsets, extended reality (XR), etc. Some of these different types of devices can be deployed in large numbers, e.g., low-complexity devices for supporting the "Internet of Things", and typically can be associated with the transmission of a relatively small amount of data with a relatively high latency tolerance. Other types of devices, such as those supporting high-definition video streaming, can be associated with the transmission of a relatively large amount of data with a relatively low latency tolerance. Other types of devices, such as those for autonomous vehicle communication and for other critical applications, can be characterized by data that should be transmitted over the network with low latency and high reliability. Depending on the application being run, a single device type may also be associated with different service profiles / characteristics. For example, different considerations can be applied to effectively support data exchange with a smartphone when it is running a video streaming application (high downlink data) compared to when it is running an Internet browsing application (sporadic uplink and downlink data) or when it is used by an emergency responder for voice communication in an emergency (data subject to strict reliability and latency requirements).

[0006] In view of this, it is desirable for current wireless communication networks, e.g., those that can be referred to as 5G or New Radio (NR) systems / New Radio Access Technology (RAT) systems, or indeed future 6G wireless communication and future iterations / releases of existing systems, to support effective connectivity with a wide range of devices associated with different applications and different characteristic data service profiles and requirements.

[0007] An example of a new service is referred to as ultra-reliable low-latency communication (URLLC) service, which, as the name implies, requires data units or packets to be communicated with high reliability and low communication latency. Another example of a new service is enhanced mobile broadband (eMBB) service, which is characterized by requiring support for high capacity up to 20 Gb / s. Thus, URLLC and eMBB types of services represent challenging examples for LTE-type communication systems and 5G / NR communication systems.

[0008] 5G NR has been continuously evolving, and current work plans include advanced 5G-NR, where some further enhancements are expected, particularly to support new use cases / scenarios with higher requirements. The desire to support these new usage cases and scenarios presents new challenges in effectively handling communication in wireless communication systems that need to be addressed. Summary of the Invention

[0009] The present disclosure can help solve or mitigate at least some of the above problems.

[0010] Embodiments of the present technology can provide a method of operating a communication device including a low-power receiver and a main receiver. The method includes: determining whether the communication device is to monitor a first signal from a wireless communication network, where the first signal includes an indication of timing information of the wireless communication network; if the communication device determines to monitor the first signal, then when the low-power receiver is in an on state and the main receiver is in an off state, receiving the first signal from the wireless communication network via the low-power receiver; and synchronizing the communication device with the wireless communication network based on the timing information of the wireless communication network. Here, the power consumption of the low-power receiver when it is in the on state is lower than the power consumption of the main receiver when it is in the on state.

[0011] In addition to the method of operating the communication device, embodiments of the present technology also relate to methods of operating infrastructure devices, communication devices and infrastructure devices, circuits for communication devices and infrastructure devices, computer programs, and computer-readable storage media, which can allow communication devices operating in a wireless communication network to save power more effectively.

[0012] Aspects and features of the present disclosure are defined in the appended claims.

[0013] It should be understood that the foregoing general description and the following detailed description are both exemplary of the present technology and not restrictive. The described embodiments and further advantages will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings. Brief Description of the Drawings

[0014] When considered in conjunction with the accompanying drawings, a more complete understanding of the present disclosure and its many attendant advantages will be readily obtained by reference to the following detailed description, where like reference numerals refer to the same or corresponding parts in several views, and where:

[0015] Figure 1 Schematically shows some aspects of an LTE-type radio telecommunication system that can be configured to operate according to certain embodiments of the present disclosure;

[0016] Figure 2 Schematically shows some aspects of a new radio access technology (NR) radio telecommunication system that can be configured to operate according to certain embodiments of the present disclosure;

[0017] Figure 3 Is a schematic block diagram of an exemplary infrastructure device and a communication device that can be configured to operate according to certain embodiments of the present disclosure;

[0018] Figure 4is a graph of user equipment (UE) processing activity over time, showing an example of a discontinuous reception (DRX) cycle;

[0019] Figure 5 is a graph of UE processing activity over time, showing an example of a paging occasion before a wake-up signal for LTE;

[0020] Figure 6 is a graph of UE processing activity over time, showing an example of a DRX cycle for 5G / NR;

[0021] Figure 7 shows the relationship between a main receiver (MR) and a low-power wake-up receiver (LP-WUR) of a UE, which can be configured to operate according to certain embodiments of the present disclosure;

[0022] Figure 8 shows an example of how a low-power wake-up signal (LP-WUS) of a UE is monitored by the LP-WUR before a paging occasion;

[0023] Figure 9 shows how the length of the LP-WUS monitoring window at the UE increases over time due to a timing offset of the LP-WUR of the UE;

[0024] Figure 10 shows a partially schematic and partially message flow diagram representation of a wireless communication system including a communication device and an infrastructure device according to an embodiment of the present technology;

[0025] Figure 11 shows a flowchart illustrating a communication process in a communication system according to an embodiment of the present technology. DETAILED DESCRIPTION

[0026] Long Term Evolution Advanced Radio Access Technology (4G)

[0027] Figure 1 provides a schematic diagram showing some basic functions of a mobile telecommunications network / system 6, which generally operates according to LTE principles, but can also support other radio access technologies and can be adapted to implement embodiments of the present disclosure described herein. Figure 1Certain aspects of the various elements and their corresponding operating modes are well known and defined in the relevant standards administered by the 3GPP (RTM) organization and are also described in many books on the subject, e.g., Holma H. and Toskala A [1]. It should be understood that the operating aspects of the telecommunications network not specifically described herein (e.g., regarding specific communication protocols and physical channels for communicating between different elements) can be implemented according to any known technology, e.g., according to the relevant standards and known proposed modifications and additions to the relevant standards.

[0028] Network 6 includes a plurality of base stations 1 connected to the core network 2. Each base station provides a coverage area 3 (i.e., a cell) within which data can be communicated with a communication device 4. Although each base station 1 is shown as a single entity in Figure 1 it should be understood by those skilled in the art that some functions of the base station can be performed by different, interconnected elements, such as an antenna (or antennas), a remote radio head, an amplifier, etc. Generally, one or more base stations can form a radio access network.

[0029] Data is transmitted from the base station 1 to the communication device 4 within its corresponding coverage area 3 via the radio downlink (DL). Data is transmitted from the communication device 4 to the base station 1 via the radio uplink (UL). The core network 2 routes data to and from the communication device 4 via the corresponding base station 1 and provides functions such as authentication, mobility management, billing, etc. The communication device can also be referred to as a mobile station, user equipment (UE), user terminal, mobile radio, terminal device, wireless transmit and receive unit (WTRU), etc. The services provided by the core network 2 can include a connection to the Internet or to an external telephone service. The core network 2 can further track the location of the communication device 4 so that it can effectively contact (i.e., page) the communication device 4 for transmitting downlink data to the communication device 4.

[0030] A base station is an example of network infrastructure equipment and can also be referred to as a transceiver station, nodeB, e-nodeB, eNB, g-nodeB, gNB, etc. In this regard, different terms are typically associated with different generations of radio telecommunications systems for elements that provide broadly comparable functions. However, certain embodiments of the present disclosure can be equally implemented in different generations of radio telecommunications systems, and for simplicity, a specific term can be used regardless of the underlying network architecture. That is, the use of a specific term associated with a particular example embodiment is not intended to imply that these implementations are limited to a particular generation of network most associated with that specific term.

[0031] New radio access technology (5G)

[0032] A system employing NR technology is expected to support different services (or service types), which may be characterized by different requirements for latency, data rate, and / or reliability. For example, enhanced mobile broadband (eMBB) services are characterized by high capacity, requiring a maximum support of 20 Gb / s. The requirements for ultra-reliable low-latency communication (URLLC) services are that a 32-byte packet is transmitted once from the radio protocol layer 2 / 3 SDU entry to the radio protocol layer 2 / 3 SDU exit point of the radio interface within 1 ms, with a reliability of 1 - 10 -5 (99.999%) or higher, 99.9999% [2].

[0033] Massive machine type communication (mMTC) is another example of a service that can be supported by an NR-based communication network. In addition, the system is expected to support further enhancements related to the industrial Internet of Things (IIoT) to support new requirements for high availability, high reliability, low latency, and in some cases high-precision positioning.

[0034] As Figure 2 shown is an exemplary configuration of a wireless communication network using some of the terms proposed and used for NR and 5G. In Figure 2 , a plurality of transmission and reception points (TRP) 10 are connected to distribution control units (DU) 41, 42 through a connection interface represented as line 16. Each of the TRP 10 is arranged to transmit and receive signals via a wireless access interface within the radio frequency bandwidth available to the wireless communication network. Thus, within the scope of performing radio communication via the wireless access interface, each of the TRP 10 forms a cell of the wireless communication network represented by circle 12. In this way, a wireless communication device 14 within the radio communication range provided by unit 12 can transmit signals to and receive signals from the TRP 10 via the wireless access interface. Each of the distribution units 41, 42 is connected to a central unit (CU) 40 (which may be referred to as a control node) via an interface 46. Then, the central unit 40 is connected to a core network 20, which may contain all other functions required to transmit data for communicating with the wireless communication device, and the core network 20 may be connected to other networks 30.

[0035] Figure 2 The elements of the radio access network shown in can operate in a manner similar to the corresponding elements of the LTE network described in the example regarding Figure 1 . It should be understood that Figure 2The operational aspects of the telecommunications network represented, as well as the operational aspects of other networks discussed herein according to embodiments of the present disclosure, which are not specifically described (e.g., regarding the specific communication protocols and physical channels for communicating between different elements), may be implemented according to any known technique, e.g., according to the currently used methods for implementing such operational aspects of a radio telecommunications system (e.g., according to relevant standards).

[0036] Figure 2 The TRP 10 of may partially have functions corresponding to those of a base station or eNodeB in an LTE network. Similarly, the communication device 14 may have functions corresponding to those of a UE device 4 known for LTE network operation. Thus, it should be understood that the operational aspects of the new RAT network (e.g., regarding the specific communication protocols and physical channels for communicating between different elements) may be different from those known from LTE or other known mobile telecommunications standards. However, it should also be understood that each of the core network components, base stations, and communication devices in the new RAT network will be functionally similar, respectively, to the core network components, base stations, and communication devices of an LTE wireless communication network.

[0037] In terms of broad top-level functions, Figure 2 the core network 20 shown connected to the new RAT telecommunications system may be broadly considered to correspond to Figure 1 the core network 2 shown, and the central unit and its associated distributed unit / TRP 10 may be broadly considered to provide functions corresponding to Figure 1 the base station 1 of Figure 1 . The term network infrastructure device / access node may be used to encompass these elements of a radio telecommunications system and more conventional base station type elements. Depending on the application at hand, the responsibility for scheduling transmissions scheduled on the radio interface between the respective distributed unit and the communication device may lie with the control node / central unit and / or the distributed unit / TRP. In Figure 2 Figure 2 , the communication device 14 is represented within the coverage area of the first communication cell 12. This communication device 14 can thus exchange signaling with the first central unit 40 in the first communication cell 12 via one of the distributed unit / TRP 10s associated with the first communication cell 12.

[0038] It should also be understood that Figure 2 Figure 2 only represents an example of the proposed architecture of the new RAT-based telecommunications system, where methods according to the principles described herein may be employed, and the functions disclosed herein may also be applied to radio telecommunications systems having different architectures.

[0039] Thus, certain embodiments of the present disclosure discussed herein may be according to various different architectures (e.g., Figure 1 and Figure 2The example architecture shown is implemented in a radio telecommunications system / network. Thus, it should be understood that the specific radio telecommunications architecture in any given implementation is not of primary significance to the principles described herein. In this regard, certain embodiments of the present disclosure may be generally described in the context of communication between network infrastructure devices / access nodes and communication devices, where the specific nature of the network infrastructure devices / access nodes and communication devices will depend on the network infrastructure to be implemented. For example, in some cases, the network infrastructure device / access node may include a base station, such as, Figure 1 the LTE-type base station 1 shown, suitable for providing functionality in accordance with the principles described herein, and in other examples, the network infrastructure device may include Figure 2 the control unit / control node 40 and / or the TRP 10 of the type shown, suitable for providing functionality in accordance with the principles described herein.

[0040] Figure 3 There is provided Figure 2 more detailed diagrams of some of the network components shown in. In Figure 3 which, as Figure 2 shown, the TRP 10 includes a radio transmitter 30, a radio receiver 32, and a controller or control processor 34, shown as a simplified representation, and the controller or control processor 34 may operate to control the transmitter 30 and the radio receiver 32 to transmit and receive radio signals to and from one or more UEs 14 within the cell 12 formed by the TRP 10. As Figure 3 shown, the example UE 14 is shown as including a corresponding transmitter 49, a receiver 48, and a controller 44, and the controller 44 is configured to control the transmitter 49 and the receiver 48 to transmit a signal representing uplink data to the radio communication network via the radio access interface formed by the TRP 10, and to receive downlink data as a signal transmitted by the transmitter 30 and received by the receiver 48 according to normal operation.

[0041] The transmitters 30, 49 and the receivers 32, 48 (and other transmitters, receivers and transceivers described with respect to the examples and embodiments of the present disclosure) may include radio frequency filters and amplifiers, as well as signal processing components and devices, in order to transmit and receive radio signals according to, for example, the 5G / NR standard. The controllers 34, 44 (and other controllers described with respect to the examples and embodiments of the present disclosure) may be, for example, a microprocessor, a CPU or a dedicated chipset, etc., configured to execute instructions stored on a computer-readable medium (such as a non-volatile memory). The processing steps described herein may be performed by, for example, a microprocessor in combination with a random access memory, operating according to instructions stored on a computer-readable medium. For ease of representation, the transmitters, receivers and controllers are shown in Figure 3are schematically shown as separate elements in the drawings. However, it should be understood that the functionality of these elements may be provided in various different ways, for example, using one or more appropriately programmed programmable computers or one or more appropriately configured application specific integrated circuits / circuit systems / chips / chip sets. It should be understood that the infrastructure equipment / TRP / base station and the UE / communication device will typically include various other elements associated with their operational functionality.

[0042] As Figure 3 shown, the TRP 10 further includes a network interface 50 connected to the DU 42 via a physical interface 16. Thus, the network interface 50 provides a communication link for data and signaling traffic from the TRP 10 via the DU 42 and the CU 40 to the core network 20.

[0043] The interface 46 between the DU 42 and the CU 40 is referred to as the F1 interface, and the F1 interface can be a physical interface or a logical interface. The F1 interface 46 between the CU and the DU can operate according to 3GPP TS 38.470 and 3GPP TS 38.473, and can be formed by an optical fiber or other wired or wireless high-bandwidth connection. In one example, the connection 16 from the TRP 10 to the DU 42 is via an optical fiber connection. The connection between the TRP 10 and the core network 20 is generally referred to as the backhaul, which includes the interface 16 from the network interface 50 of the TRP 10 to the DU 42 and the F1 interface 46 from the DU 42 to the CU 40.

[0044] In order for a UE (e.g., UE 4 or 14) to transmit uplink data (e.g., on a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH)) to, for example, the base station 1 or the TRP 10, the UE must first ensure synchronization with the network on the uplink. Since a particular eNB or gNB expects to receive communications from many UEs, it is necessary to ensure a common timing understanding (i.e., synchronized in terms of the start time of frames and orthogonal frequency division multiplexing (OFDM) symbols) with each of these UEs. This enables the eNB to schedule communications with each of them in a manner that avoids collisions and ensures the orthogonality of the uplink signals, thereby avoiding or mitigating inter-carrier interference.

[0045] Power Saving and Discontinuous Reception (DRX) in NR

[0046] In an atypical currently deployed network, a communication device can operate in a discontinuous reception (DRX) mode, in which the communication device wakes up (i.e., powers on its receiver) to receive signals during its DRX wake-up time. DRX operation can be performed when the communication device is in an idle mode or a connected mode. In the connected mode, the communication device is configured to periodically monitor the physical downlink control channel (PDCCH) in a group of time slots or subframes. If no PDCCH addressed to the communication device with a radio network temporary identifier (RNTI) is detected during that group of time slots or subframes, the communication device can sleep for the next cycle of the periodicity. Power saving is an important aspect of the user experience of wireless radio access technologies such as NR, which will affect the adoption of 5G and future generations of mobile phones and / or services. DRX is a power saving method for NR communication devices.

[0047] The basic DRX cycle is as Figure 4 shown and consists of a DRX on-duration of T DRX-ON and an inactivity duration of T DRX-OFF (i.e., DRX off-duration), where the DRX on-duration occurs periodically in the DRX cycle P DRX . During the DRX on-duration, the UE turns on its receiver to monitor the downlink traffic, and during the DRX off-duration, it turns off its receiver to save power consumption. The DRX parameters T DRX-ON & P DRX are configured by the network. Those skilled in the art should understand that this basic operation may not always be efficient, especially if the UE frequently does not receive any signals during the on-duration (or active operating mode) of the DRX operation.

[0048] Wake-up signals for power saving

[0049] There are many different ways to improve the battery life of the UE. One such way is to make the DRX configuration adaptable to the UE's expected data reception or transmission profile. For example, a wake-up signal (WUS) can be used to indicate whether the UE should wake up during the DRX on-duration. The WUS is a signal or channel transmitted to the UE or a group of UEs before the DRX on-duration or a paging occasion (PO) to indicate whether the UE needs to wake up during that on-duration and monitor for possible traffic, e.g., monitor the PDCCH. Using the WUS signal in this way to wake up the UE recognizes that not every DRX on-duration contains traffic for the UE, and for such cases, PDCCH monitoring consumes unnecessary power from the UE, which can be avoided by this WUS signaling.

[0050] Technologies such as eMTC, NB-IoT, and 5G NR all support wake-up signals. Before the paging occasion, the eMTC / NB-IoT wake-up signal (WUS) is used in the IDLE mode. If the UE detects the WUS, it wakes up and monitors the subsequent paging occasion of the MTCPDCCH (MPDCCH) or NB-IoT (NPDCCH) that may further allocate paging messages. If the UE does not receive the WUS, it can return to sleep. The WUS consists of a known sequence. The UE can monitor the WUS by performing correlation on this known sequence. As described above, the WUS can be shared by all UEs associated with the paging cycle, or can be associated with a group of UEs associated with the paging cycle.

[0051] An example of the WUS is illustrated by a timing diagram that shows the Figure 5 graph of the transmission power and UE receiver activity provided therein versus time. As Figure 5 shown, the wake-up signal WUS 51 appears at a known time offset τ2-τ1 52 before the paging occasion 54. The time offset 52 allows the UE to "start" its main receiver (MR) after receiving the WUS and before the paging occasion 54. As a result, the WUS itself can be monitored with a low-power receiver because the low-power receiver does not need to be able to receive all the characteristics of the signals that the MR can receive. Only when there is an MPDCCH transmission in the paging occasion 54, at time τ 1 , as Figure 5 shown, the WUS is transmitted before the paging occasion 54. When the WUS is UE-specific (i.e., each UE has its own WUS), the WUS of that UE is sent only when there is an MPDCCH transmission targeted at that UE in that paging occasion. When the WUS is group-specific (i.e., a group of UEs share a WUS), the WUS of that group is sent when there is an MPDCCH targeted at at least one UE in that group in that paging occasion. Once the WUS is detected, if necessary, the UE will continue to fine-tune its frequency and timing tracking loops, and blindly detect the MPDCCH between times τ 2 and τ 3 , and subsequently decode the PDSCH carrying the paging message between times τ 3 and τ 4 . If the UE fails to detect the WUS, it will return to sleep and skip the detection of the MPDDCH. Thus, by using the WUS, the UE will consume less energy by avoiding unnecessary MPDCCH monitoring. It should be understood that when using DRX, the WUS can also be used in the connected mode.

[0052] In some examples, the WUS can be a physical channel that contains very little information (e.g., a UE ID or a single bit indicating that the UE monitoring the WUS should wake up), so the UE can decode the WUS very quickly compared to blind decoding for the MPDCCH. The WUS can also be encoded in a format that allows low-power decoding; for example, the WUS can be a narrow-bandwidth signal that can be decoded at low power using a low-sampling-rate receiver.

[0053] For an example of 5G NR, the wake-up signal WUS is used for connected-mode DRX operation [3], and the 5G NR WUS is based on the PDCCH that carries downlink control information (DCI). The PDCCH can be referred to as the power-saving - PDCCH (PS-PDCCH), and the monitoring period of this PDCCH is called the PS-PDCCH monitoring period. Here, the term PS-PDCCH is synonymous with "PDCCH scrambled with a PS-RNTI". This monitoring period can also be referred to as the "power-saving monitoring period". The NR WUS is described in more detail in [4],

[0054] Figure 6 An example timing diagram is shown, showing the transmission of signals for 5G NR operation in the connected mode over time. As Figure 6 shown, the PS-PDCCH 61 appears in the search space before the DRX_ON phase 62 of the DRX cycle represented by the double arrow 64. This example represents a full connected-mode DRX cycle. The time position of the PS-PDCCH 61 reaches the amount PS_offset 66 earlier than the DRX_ON phase 62. The UE decodes the DCI within the PS-PDCCH. Since the UE only needs to decode the PS-PDCCH, it does not have to operate its complete receiver circuit, so the PS-PDCCH can be decoded with lower received power. If the DCI indicates that the UE should wake up, the UE wakes up its complete receiver circuit during the next DRX_ON duration 62. Otherwise, the UE can go to sleep after the PS-PDCCH and does not have to decode other PDCCHs during the DRX_ON duration 62.

[0055] At the time of filing this disclosure, 3GPP has started a research project on low-power receivers and low-power wake-up signals for NR-5G [5]. As described in Section 3 of [5], the reasons for this research are as follows.

[0056] The 5G system is designed and developed for mobile phones and vertical use cases. In addition to latency, reliability, and availability, UE energy efficiency is also crucial for 5G. Currently, 5G devices may need to be charged weekly or daily, depending on individual usage times. Generally, 5G devices consume dozens of milliwatts in the RRC idle / inactive state and hundreds of milliwatts in the RRC connected state. Therefore, a design for extending battery life is necessary to improve energy efficiency and provide a better user experience.

[0057] For UEs without continuous energy sources, such as those using small rechargeable and single button cells, energy efficiency is even more important. In vertical use cases, sensors and actuators are widely deployed for monitoring, measuring, charging, etc. Generally, their batteries are non-rechargeable and are expected to last at least several years. Such UEs can be wearable devices, which can include smartwatches, rings, electronic health-related devices, and medical monitoring devices. For typical battery capacities, it is challenging to maintain power for up to one or two weeks as needed.

[0058] Power consumption depends on the configured length of the wake-up cycle, such as the paging cycle. To meet the battery life requirements mentioned above, it is desirable to use long-duration eDRX cycles, which result in high latency and are not suitable for services that require both long battery life and low latency simultaneously. For example, in the fire detection and extinguishing use case, within one or two seconds from the time the fire is detected by the sensor, the fire shutters should close and the fire sprinklers should be activated by the actuator; thus, long eDRX cycles cannot meet the latency requirements. Therefore, eDRX does not seem suitable for latency-critical use cases. Therefore, the aim is to study ultra-low power mechanisms that can support low latency (e.g., lower than eDRX latency) in Rel-18.

[0059] Currently, the UE needs to wake up periodically once per DRX cycle, which dominates the cycles without signaling or data traffic. If the UE can wake up only when triggered (e.g., via paging), the power consumption can be significantly reduced. This can be achieved by using the wake-up signal (WUS) as described above to trigger the main radio, and an independent receiver at the UE that has the ability to monitor the wake-up signal with ultra-low power consumption without powering on the main radio (MR). The MR is used for data transmission and reception and can be turned off or set to deep sleep unless it is turned on.

[0060] The power consumption for monitoring a wake-up signal depends on the wake-up signal design and the hardware modules of the wake-up receiver used for wake-up signal detection and processing. The research in [5] mainly focuses on low-power WUS and wake-up receiver (WUR) for small-sized devices sensitive to power consumption, including IoT use cases (e.g., industrial sensors, controllers) and wearable devices. Other use cases are not excluded, e.g., extended reality (XR) / smart glasses, smartphones, etc.

[0061] Therefore, the goal is to support low-power wake-up signals (LP-WUS) received by a low-power wake-up receiver (LP-WUR). If the LP-WUR detects an LP-WUS, the main receiver (MR) of the UE is woken up, and then the MR can decode the data transmitted by the network. Figure 7 The relationship between the MR 71 and the LP-WUR 72 of the UE is shown.

[0062] The LP-WUR 72 receives the signal RX_sig2 and monitors the LP-WUS within RX_sig2. If the LP-WUR 72 detects an LP-WUS, it wakes up the MR 71 via, for example, an "on / off" indication 73. Then, the MR 71 decodes its input signal RX_sig1 and receives the data 74, which can then be forwarded to a buffer or a processor of the UE, etc. In some cases, RX_sig2 is the same as RX_sig1. For example, RX_sig1 and RX_sig2 can refer to the system bandwidth of an NR waveform. In other cases, RX_sig1 and RX_sig2 are different. For example, RX_sig1 can be the system bandwidth of an NR waveform, and RX_sig2 can be a narrower bandwidth of an in-band or out-of-band signal.

[0063] In the IDLE mode, the LP-WUS can be used to wake up the MR so that the UE can monitor the paging occasion (PO). That is:

[0064] ● If an LP-WUS is detected, the UE wakes up the MR, and the UE decodes the PO; or

[0065] ● If no LP-WUS is detected, the MR is not woken up.

[0066] Figure 8Shows the case of using LP-WUS 81 to wake up an IDLE mode UE to monitor paging messages during a paging occasion (PO). During the LP-WUS monitoring window, the LP-WUR of the UE monitors LP-WUS 81. The LP-WUR of the UE knows that if the network is to transmit LP-WUS 81, it will be transmitted during the LP-WUS monitoring window. Therefore, during this LP-WUS monitoring window, the LP-WUR only needs to actively monitor LP-WUS 81. If LP-WUS 81 is detected, the LP-WUR wakes up the MR (it should be understood by those skilled in the art that this process may take some time, e.g., 100 ms). Then, the MR monitors the PDCCH 82 during paging. If the UE receives a PDSCH 83 containing its identifier during the PO, the UE performs the initial access procedure with the network. During the wake-up of the MR, the MR needs to synchronize with the network and may read system information. It should be understood here that if LP-WUS is not detected, the LP-WUR does not need to wake up the MR

[0067] Some LP-WUR architectures have low enough power consumption so that these architectures can be "always on". Other LP-WURs have higher power consumption or are implemented in UEs that require lower power consumption. Therefore, for those LP-WURs, it is beneficial to monitor LP-WUS only in the LP-WUS monitoring window (i.e., in a DRX-like manner).

[0068] To reduce costs and operate at low power, the LP-WUR can operate with the following characteristics:

[0069] ● The LP-WUR may have a clock with poor frequency accuracy. Operating with a ring oscillator instead of a crystal oscillator will reduce power consumption, cost, and complexity. The frequency accuracy of the ring oscillator is lower than that of the MR's oscillator, and the timing offset is higher. The MR clock is usually based on a crystal oscillator. When the MR wakes up (i.e., "turns on"), the frequency and / or timing of the ring oscillator can be reset to the MR clock. Use a tracking synchronization signal block (SSB) such as a phase-locked loop to synchronize the MR clock with the gNB. When the MR is inactive, the MR clock is turned off; at this time, the LP-WUR needs to rely on its own ring oscillator because the high-accuracy MR clock is no longer available.

[0070] ● LP-WUS may use a waveform different from the NR waveform. This waveform may not need to be synchronized with the synchronization signals of the NR waveform (e.g., SSB and demodulation reference signal (DMRS)).

[0071] The inaccuracy of the LP-WUR clock relative to the gNB clock means that the UE will need to turn on in advance for a period of time equal to the maximum inaccuracy between the gNB and UE clocks to monitor the LP-WUS monitoring window, so as to ensure that the LP-WUS is not missed when it is transmitted exactly at the end of the monitoring window and the timing of the LP-WUR has been offset by the maximum amount.

[0072] The UE will be designed to have some knowledge of the maximum potential error of its clock (e.g., the frequency error of its clock). The UE can use this information to determine the maximum inaccuracy of its LP-WUR clock. For example, consider the case where the maximum time offset rate between the LP-WUR clock and the gNB clock is ±T drift_rate . If the LP-WUS monitoring window appears every T DRX seconds, then after the first LP-WUS monitoring window, the LP-WUR clock will generate a timing inaccuracy of T drift_rate × T DRX , and after the second LP-WUS monitoring window, it will generate 2 × T drift_rate × T DRX , and so on. Therefore, the LP-WUR will have to "turn on" for longer and longer periods to ensure that the LP-WUR is actually on during the duration of the LP-WUS transmission window (where the LP-WUS transmission window is the time window during which the gNB may transmit the LP-WUS. In the case where the UE clock is fully synchronized with the gNB, the LP-WUS monitoring window of the UE is the same as the LP-WUS transmission window of the gNB); this will of course increase the average power consumption of the LP-WUR because it will be on for a longer time.

[0073] The impact of time offset on the length of the LP-WUS monitoring window is shown as Figure 9 . In Figure 9 , three LP-WUS monitoring windows are shown. Reference instances A, B, and C are used to describe the LP-WUS monitoring window.

[0074] ● A: The LP-WUR operates in such a way that its LP-WUS monitoring window is synchronized with the LP-WUS transmission window of the gNB. For example, the UE may have been operating with its main radio "on" recently, in which case an accurate synchronization with the gNB clock will be obtained. In this case, the UE monitoring window for the LP-WUS is the same as the LP-WUS transmission window at the gNB (where this LP-WUS transmission window is the time window during which the gNB can transmit the LP-WUS91 before the paging occasion, where the gNB can transmit the PDCCH and PDSCH for the UE or another UE during the paging occasion);

[0075] ● B: The LP-WUR has been operating on an inaccurate oscillator that is not synchronized with the gNB. The inaccuracy of the oscillator means that there is uncertainty at the UE regarding the position of the LP-WUS transmission window of the gNB (where, in instance B, there is no LP-WUS 92 transmission). Therefore, the UE must extend its LP-WUS monitoring window by the amount of time T before the cursor drift_rate ×T DRX , and continue for the amount of time T after the cursor drift_rate ×T DRX . This extension of the UE's LP-WUS monitoring window ensures that the UE's inaccurately timed LP-WUS monitoring window overlaps with the LP-WUS transmission window of the gNB;

[0076] ● C: Since the LP-WUR has not been resynchronized since A (and there is no LP-WUS 93 transmission in instance C either), the possible timing error between the UE and the gNB may have increased by an additional amount of time T drift_rate ×T DRX . Therefore, the UE's LP-WUS monitoring window must start at the amount of time 2×T before the cursor drift_rate ×T DRX , and continue for the amount of time 2×T after the cursor drift_rate ×T DRX .

[0077] From the above discussion and Figure 9 it can be seen that as the potential timing error of the LP-WUR increases, the duration of the LP-WUS monitoring window of the LP-WUR needs to increase. As the time since the LP-WUR was last resynchronized increases, the potential timing error at the UE gradually increases. The result of the increase in the LP-WUS monitoring window of the LP-WUR is that the LP-WUR will consume more average power (the LP-WUR will be "on" for a larger portion of the LP-WUS-DRX cycle), and this problem will persist as long as the UE and / or the LP-WUR are not resynchronized with the network.

[0078] The LP-WUR timing can be resynchronized in any of the following cases:

[0079] ● The LP-WUR detects an LP-WUS, where the LP-WUS has a structure that allows for the derivation of accurate timing; or

[0080] ● The UE turns on its primary radio and synchronizes to the primary 5G NR signal (i.e., synchronizes to the SSB). The updated timing information obtained by the MR can then be transmitted to the LP-WUR.

[0081] Accordingly, the technical problem to be solved is how to provide means for the LP-WUR to minimize its timing uncertainty, such that the size of its LP-WUS monitoring window can be reduced, and thus average power consumption can be saved. Accordingly, embodiments of the present technology seek to provide solutions to address such problems.

[0082] Low-Power Wake-Up Signal Synchronization

[0083] Figure 10 A partial schematic diagram and a partial message flow chart representation of a wireless communication system including a communication device (e.g., a UE) 101 and an infrastructure device (e.g., a gNB) 102 are shown, in accordance with at least some embodiments of the present technology. The communication device 101 is configured to transmit signals to and / or receive signals from a wireless communication network, e.g., transmit signals to and receive signals from the infrastructure device 102. Specifically, the communication device 101 may be configured to transmit data to and / or receive data from a wireless communication network via a radio frequency interface provided by the wireless communication network (e.g., the Uu interface between the communication device 101 and a radio access network (RAN), including the infrastructure device 102). The communication device 101 includes a main receiver (or main receiver circuit) 101.1, a low-power receiver (or low-power receiver circuit) 101.2, and at least one controller (or controller circuit) 101.3, 101.4, while the infrastructure device 102 includes a transceiver (or transceiver circuit) 102.1 and a controller (or controller circuit) 102.2. Each of the controllers 101.3, 101.4, 102.2 may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc. In Figure 10 the example shown, two controllers 101.3, 101.4 are shown, where the first controller 101.3 is operatively coupled to (and thus controls) the main receiver 101.1, and the second controller 101.4 is operatively coupled to (and thus controls) the low-power receiver 101.2. Those skilled in the art should understand that this would be advantageous because the main CPU of the communication device 101 (e.g., the controller 101.3) may be more powerful than the CPU (e.g., the controller 101.4) connected to the low-power receiver 101.2, and if it needs to be powered on to control the low-power receiver 101.2, it will consume a large amount of power. Of course, those skilled in the art should understand that in some arrangements of embodiments of the present technology, the communication device 101 may include a single controller (or controller circuit) for controlling the main receiver 101.1 and the low-power receiver 101.2.

[0084] As Figure 10As shown in the example of, at least one of the controllers 101.3, 101.4 of the communication device 101 is configured to control the communication device 101 to determine 104 whether the communication device 101 is to monitor a first signal from a wireless communication network (e.g., from the infrastructure device 102), wherein the first signal includes an indication of timing information of the wireless communication network (e.g., the timing information of the infrastructure device 102), so that in the case where the communication device 101 determines to monitor the first signal, when the low-power receiver 101.2 is in the on state and the main receiver (MR) 101.1 is in the off state, the first signal is received 106 from the wireless communication network (e.g., from the infrastructure device 102) via the low-power receiver 101.2 (LPR / LP-WUR), and the communication device 101 is synchronized 108 with the wireless communication network (e.g., with the infrastructure device 102) based on the timing information of the wireless communication network (e.g., the timing information of the infrastructure device 102). Here, the power consumption of the low-power receiver 101.2 when it is in the on state is lower than the power consumption of the main receiver 101.1 when the main receiver 101.1 is in the on state.

[0085] In essence, embodiments of the present technology thus propose that the gNB send a signal (which can be a signal having a LP-WUS or a structure similar to LP-WUS) to the LP-WUR, allowing the LP-WUR to resynchronize its timing with the gNB. Resynchronization of the LP-WUR does not require turning on the main radio (MR) of the UE because a LP-WUS-like signal can be received or decoded by the LP-WUR. According to embodiments of the present technology described herein, the signal can be an actual LP-WUS or a modified LP-WUS, or in fact any signal having a structure similar to LP-WUS or some other structure that enables the signal to be received and decoded by the LP-WUR without involving the MR, and can be interchangeably referred to as the first signal, LP-WUS, or resynchronization (or resync) LP-WUS.

[0086] In some arrangements of embodiments of the present technology, the LP-WUR of the UE synchronizes with the received LP-WUS, but the LP-WUS does not wake up the UE (in other words, does not wake up the MR of the UE). In this arrangement of embodiments of the present technology (and in other arrangements of embodiments of the present technology), it is assumed that the LP-WUS has a structure that allows the LP-WUR to synchronize with it. Those skilled in the art should understand that such a signal is different from some known signals in terms of NR and eMTC. For example, a wake-up signal (WUS) indicating that the UE should wake up, a go-to-sleep signal (GTS) indicating that the UE should enter sleep (and / or not wake up), and a wake-up and go-to-sleep signal (WGTS) indicating that the UE should wake up or enter sleep. The first signal / resynchronization LP-WUS / LP-WUS-like signal described herein is different from these signals in terms of intention because the UE is not instructed whether to enter sleep or wake up; instead, the UE is allowed to synchronize with the network. However, according to certain arrangements of embodiments of the present technology, in the case where such a first signal / resynchronization LP-WUS / LP-WUS-like signal conflicts with a traditional type of signal (e.g., a WUS or GTS signal), the UE will regard such a traditional signal as having a higher priority and will veto the first signal / resynchronization LP-WUS / LP-WUS-like signal. Of course, by receiving a WUS / GTS / WGTS signal and taking appropriate actions, the UE will also synchronize with the network at the same time.

[0087] In some arrangements of embodiments of the present technology, the LP-WUS may include a "wake-up" bit. The LP-WUS may include a bit or flag having two states: for example, (1) "wake-up" and (2) "not wake-up". In other words, the LP-WUS may indicate (e.g., may include a bit indicating) whether the primary receiver should switch from the off state to the on state in response to the low-power receiver receiving the LP-WUS signal, where it may be the LP-WUR that determines to wake up the primary receiver based on this indication / bit in the LP-WUS. If the UE has not been woken up for a long time and thus may need to re-synchronize, but does not need to be woken up to receive any other signaling or data, the gNB may send an LP-WUS with the bit set to "do not wake up". By receiving the LP-WUS, the LP-WUR will re-synchronize with the gNB's clock and thus can reset its LP-WUS monitoring window to the gNB's LP-WUS transmission window. When the bit is set to "not wake up", the LP-WUR of the UE can perform this re-synchronization without further waking up its primary receiver. In some such arrangements, this indication or bit may not have to be understood as a "wake-up or not wake-up" bit, but rather as a bit included within a normal LP-WUS that overrides the normal function of the LP-WUS and indicates to the UE that the MR should not actually be woken up when receiving this LP-WUS.

[0088] In some arrangements of embodiments of the present technology, the gNB may send an LP-WUS having an identity that does not match that of the specific UE receiving it. For an LP-WUS signal that includes a synchronization sequence following a certain UE / LP-WUR identity, all UEs may synchronize to this synchronization sequence even if at least some of these UEs have not woken up because the UE / LP-WUR identity does not match (i.e., does not match one or more or all of the UEs receiving it). In other words, the LP-WUS may include an indication of one or more communication device identities, and none of the one or more indicated communication device identities match the identity of this communication device. In this case, sending an LP-WUS to any UE will allow all other UEs to re-synchronize. Thus, in such an arrangement where the gNB does not need to wake up any UE to which it transmits the LP-WUS, the gNB sends an LP-WUS having an identity that does not match any UE. This will allow all UEs to synchronize to the LP-WUS, but in fact no UE will wake up its primary receiver.

[0089] In some arrangements of embodiments of the present technology, the gNB may rotate the UEs that are woken up only for resynchronization purposes. Similar to the arrangement described in the previous paragraph, the gNB may send LP-WUS to several UEs with the identity of a UE (UE_A), which actually wakes up the UE_A. The UE_A will wake up and turn on its primary radio. However, the LP-WURs of the other UEs to which the LP-WUS is transmitted will resynchronize to the same synchronization sequence. Although in this case, the UE_A is woken up when it does not need to be woken up, at a future time, another UE (UE_B) will be woken up. Therefore, the pain of wrongly waking up a UE just to allow the LP-WURs of other UEs to resynchronize can be shared among multiple UEs. In other words, the LP-WUS may indicate (e.g., by including an identifier of the communication device) that the communication device is to switch its primary receiver from the off state to the on state in response to the low-power receiver receiving the LP-WUS signal, and wherein the infrastructure device may be configured to transmit the LP-WUS to the communication device and one or more other communication devices according to a cyclic schedule determined by the infrastructure device. Here, it should be understood that if the gNB determines that a particular UE (i.e., the MR of the UE) may need to be woken up for another purpose, e.g., to transmit control signaling or data to the UE, the gNB may move the UE to the back of the cyclic schedule queue to avoid having to wake up the UE again in the nearest future.

[0090] In some arrangements of embodiments of the present technology, the gNB may send broadcast LP-WUS identified by a group of UEs (e.g., UEs that support LP-WUS or a selected group of those UEs that support LP-WUS). The broadcast LP-WUS may have a known sequence that indicates to the UEs that it is used only for resynchronization purposes, and the UEs do not need to wake up their MRs. In other words, the LP-WUS signal may be received from the wireless communication network as a broadcast signal broadcast to the communication device and one or more other communication devices, wherein the broadcast LP-WUS includes an indication that the primary receiver does not switch from the off state to the on state in response to the low-power receiver receiving the broadcast LP-WUS signal.

[0091] If the LP-WUR is not awakened within multiple DRX cycles and if the timing offset at the UE is large enough, the timing error at the UE may become greater than the time taken to transmit the LP-WUS. In this case, even if the LP-WUR is synchronized with the LP-WUS, the position of the LP-WUS within the LP-WUS transmission window of the gNB is not known, and thus the start and end times of the LP-WUS transmission window of the gNB cannot be determined. Therefore, to solve this problem, in some arrangements of embodiments of the present technology, the LP-WUS may indicate the transmission position within the LP-WUS transmission window.

[0092] In some arrangements of embodiments of the present technology, a bit sequence in the LP-WUS may identify the position of the LP-WUS or LP-WUS-like signal within the LP-WUS transmission window. The bit sequence may indicate the time index of the LP-WUS within the LP-WUS transmission window. In other words, the indication of the timing information of the wireless communication network may include a sequence of one or more bits indicating the time index of the first signal within the transmission window during which the first signal may be transmitted by the wireless communication network, where the transmission window here is such a window during which the LP-WUR of the UE should be turned on to monitor the LP-WUS signal (of course, with respect to the timing offset of the UE, the on-period of the LP-WUR may be time-shifted with respect to the transmission window, and thus an indication of the time index of the LP-WUS within the transmission window is required).

[0093] In some arrangements of embodiments of the present technology, the time index may indicate the position of the start of the LP-WUS transmission (e.g., subframe / slot / sub-slot number). In other words, the time index of the first signal within the transmission window may be the start position of the first signal within the transmission window. Alternatively, the end of the LP-WUS transmission may be indicated. In other words, the time index of the first signal within the transmission window may be the end position of the first signal within the transmission window.

[0094] In some arrangements of embodiments of the present technology, a time index may indicate an index of an LP-WUS transmission. If (the UE and the network) know that the LP-WUS transmission window has room in time for transmitting a specific number N of LP-WUS signals, then this index may indicate in which one of the N LP-WUS transmission opportunities the LP-WUS has been transmitted. In other words, the transmission window may include multiple possible positions for the first signal, and the time index of the first signal within the transmission window may be one of the multiple possible positions where the wireless communication network transmits the first signal. For example, if the LP-WUS transmission window is 16 time slots long and each LP-WUS has a duration of two time slots, then there is room for N = 8 LP-WUSs. If the index is enumerated from 0 to 7 and the index indicates "1", then the LP-WUR should understand that the LP-WUS has been transmitted in the second index, i.e., two (2 × "1" = 2) time slots after the start of the LP-WUS transmission window. The LP-WUR can then adjust its monitoring window for the LP-WU to start two time slots before the time of receiving the LP-WUS.

[0095] In some arrangements of embodiments of the present technology, a bit sequence in the LP-WUS may identify the position of the LP-WUS or LP-WUS-like signal relative to the start of a paging occasion. The bit sequence may indicate the time index of the LP-WUS relative to the start of the paging occasion. In other words, the indication of the timing information for the wireless communication network may include a sequence of one or more bits indicating the time index of the first signal relative to the start of the paging cycle associated with the communication device.

[0096] In some arrangements of embodiments of the present technology, a synchronization sequence may identify the position of the LP-WUS or LP-WUS-like signal within the LP-WUS transmission window. Thus, LP-WUS signals transmitted at different times within the LP-WUS transmission window may use different synchronization sequences. In other words, the indication of the timing information for the wireless communication network may include the synchronization sequence used by the wireless communication network when transmitting the first signal, and this synchronization sequence may be one of the multiple possible synchronization sequences, each possible synchronization sequence being associated with one of the multiple possible positions of the first signal within the transmission window. By synchronizing to a specific synchronization sequence, the UE can determine the position of the received LP-WUS within the LP-WUS transmission window and thus can adjust the start of its LP-WUS monitoring window accordingly.

[0097] As those skilled in the art should understand, the disadvantage of such an arrangement described in the previous paragraph is that the UE will have to perform blind decoding on multiple LP-WUS synchronization sequences, thus increasing the complexity and power consumption of the LP-WUR. It should be noted here that a UE with a better timing offset can synchronize to fewer sequences, thus allowing for a design trade-off. For example, if the timing offset is small, the LP-WUR will know which synchronization sequence or which subset of the synchronization sequences may be active at a certain time. However, if the timing offset is larger, the LP-WUR may need to attempt to synchronize with more sequences, and so on. Then, the UE design can make a trade-off between the timing offset requirement and the requirement to attempt to synchronize with multiple sequences.

[0098] In some arrangements of embodiments of the present technology, a signal with an LP-WUS structure can be sent at certain (known) times to allow the LP-WUR to synchronize with the signal. It should be noted that in this case, and in fact in all arrangements of the embodiments of the present technology described herein, a signal with an "LP-WUS structure" is a signal that can be decoded by the LP-WUR. As an example, if the LP-WUR is based on an RF envelope detector, a signal with an LP-WUS structure may contain a synchronization sequence using an on-off keying (OOK) waveform. The UE is capable of synchronizing with a signal with an LP-WUS structure. Those skilled in the art should understand that the UE / LP-WUR typically monitors the LP-WUS during the LP-WUS monitoring period before its paging occasion (PO). However, different groups of UEs have different paging occasions. This means that if the gNB needs to send an LP-WUS to re-synchronize the LP-WUR / UE (e.g., according to the above embodiments), multiple LP-WUSs need to be sent in order to re-synchronize all UEs with different paging occasions. Obviously, for the gNB, it would be more efficient to send fewer (or actually a single) LP-WUS to a group of UEs for re-synchronization purposes. Therefore, the re-synchronization signal (e.g., an LP-WUS-like signal) can be sent by the gNB at a specific time known to the UE, rather than before the specific PO of each UE. Thus, all UEs can re-synchronize to the same re-synchronization signal.

[0099] In some arrangements of embodiments of the present technology, a resynchronization LP-WUS signal may be sent at a known time (sent to a UE and one or more other UEs at the same known time). For example, the transmission timing may be signaled in a system information block (SIB), or the UE may be signaled in any suitable manner. When the UE resynchronizes to the signal, the precise timing of the resynchronization LP-WUS signal is known. In other words, the communication device may be configured to determine that a first signal will be transmitted by the wireless communication network at a specific time, and to monitor the first signal at the specific time. Here, the known time may be based on a maximum timing offset, which may be indicated by the UE to the network in UE capability information. In other words, the infrastructure device may be configured to receive capability information of the communication device from the communication device when the communication device is in a connected state with the infrastructure device, wherein the capability information of the communication device includes an indication of a maximum offset rate of a clock of the communication device, and the specific time is determined based on the maximum offset rate of the clock of the communication device.

[0100] In some arrangements of embodiments of the present technology, a resynchronization LP-WUS signal may be transmitted within a window (transmitted to the UE and one or more other UEs within the same known window). In other words, the communications device may be configured to determine that a first signal will be transmitted by the wireless communications network within a specified time period, and to monitor the first signal during the specified time period. Scheduling flexibility is provided to the gNB compared to the arrangements of embodiments of the present technology described in the previous paragraph. It will be appreciated by those skilled in the art that the UE will have to determine the position in the window where the resynchronization LP-WUS signal is transmitted (e.g., one of the arrangements according to embodiments of the present technology described above in relation to the LP-WUS, the LP-WUS including a bit sequence or synchronization sequence indicating its position in the transmission window).

[0101] In some arrangements of embodiments of the present technology, the resynchronization LP-WUS signal may allow for mobility-related measurements. For example, the signal will indicate the cell from which it was transmitted, thereby allowing the UE to determine (e.g., by performing measurements on the received signal) whether it is still camped on a suitable cell or whether the UE should perform measurements on signals from neighboring cells in order to potentially perform a handover or other mobility procedure. In other words, the first signal includes an indication of the cell of the wireless communication network from which the first signal was transmitted.

[0102] In some arrangements of embodiments of the present technology, the gNB may send a resynchronization LP-WUS, but the UE may decide whether to read it. Different UEs may have different clocks, resulting in different offset rates T drift_rate . The clock is good and T drift_rateSmaller UEs can benefit from less frequent resynchronization and thus save more power by not having to turn on their LP-WURs as frequently. In other words, a communication device can be configured to determine whether the communication device is to monitor a first signal based on the accuracy of the communication device's clock. Here, the gNB can periodically send a resynchronization LP-WUS, e.g., with a fastest T drift_rate as the target, which may be unnecessary for UEs with more accurate clocks. Thus, in this arrangement of embodiments of the present technology, the UE can decide when to read the resynchronization LP-WUS. It should be noted here that all UEs must know the periodicity of the resynchronization LP-WUS in order to know when to attempt to receive the LP-WUS and when to skip the reception / decoding of the LP-WUS. It should also be noted here that this arrangement of embodiments of the present technology is applicable when it is known that the resynchronization LP-WUS is sent at a different time to the "real LP-WUS" (i.e., the LP-WUS that requires the UE to wake up by turning on the MR because it needs to receive a PDCCH or PDSCH etc. from the gNB).

[0103] In at least some arrangements of embodiments of the present technology, the gNB can periodically broadcast a resynchronization LP-WUS to a group of UEs. Here, the gNB may not need to make any determination as to whether each UE in the group needs resynchronization, but rather the UE can decide whether to read the resynchronization LP-WUS, e.g., based on its clock accuracy as described above, or whether the UE determines that it is already synchronized, or was last synchronized within an acceptable amount of time prior, as described in the following paragraphs. In other words, an infrastructure device can be configured to periodically transmit a first signal to one or more communication devices, the first signal including an indication of the timing information of the infrastructure device for the one or more communication devices to use to synchronize the one or more communication devices with the infrastructure device based on the timing information of the infrastructure device. Here, the infrastructure device can be configured to periodically transmit the first signal to the low-power receiver of each of the one or more communication devices when the low-power receiver of each communication device is in an on state and the main receiver of each communication device is in an off state, and wherein the power consumption of the low-power receiver of each communication device is lower when the low-power receiver of each communication device is in an on state than the power consumption of the main receiver of each communication device when the main receiver of each communication device is in an on state.

[0104] In some arrangements of embodiments of the present technology, when the gNB knows that the UE / LP-WUR may be out of sync, the gNB may send LP-WUS only for synchronization purposes. As those skilled in the art should understand, there are moments when the UE / LP-WUR must wake up anyway. When waking up at such a moment, the UE / LP-WUR will regain synchronization and will thus be able to reset its LP-WUS monitoring window. Therefore, the gNB does not need to send LP-WUS for synchronization purposes close to such a time, as this would unnecessarily require turning on the LP-WUR of the UE, thus consuming unnecessary power. In other words, the infrastructure device may be configured to determine whether communication needs to be synchronized with the infrastructure device based on the length of time since the communication device last synchronized with the infrastructure device, and if the infrastructure device determines that the communication device does not need to be synchronized with the infrastructure device, determine that the infrastructure device will skip transmitting the first signal to the communication device. Here, the length of time may be a time length fixed in the specification and known to the UE, indicated to the UE by the network in any suitable manner (wherein, in some examples, it may be determined by the network based on the UE indicating its maximum offset rate within the UE capability information, assuming this is done when the UE is in the connected mode), or determined by the UE in other ways.

[0105] Those skilled in the art should also understand that if the gNB skips the transmission of re-synchronization LP-WUS at certain times (or, indeed, even if it does not skip), and the UE itself realizes that it has been synchronized with the network recently enough, the UE may decide to skip monitoring for such re-synchronization LP-WUS at such certain times. In other words, the communication device may be configured to determine whether the communication device is to monitor the first signal based on the length of time since the communication device last synchronized with the wireless communication network.

[0106] In some arrangements of embodiments of the present technology, based on receiving system information updates, the UE may have been recently synchronized with the network. When certain system information is updated, the UE will have to read the system information. Therefore, after receiving such updated system information, the gNB does not need to send LP-WUS to re-synchronize the UE / LP-WUR, or the UE does not need to monitor such re-synchronization LP-WUS. In other words, the infrastructure device may be configured to determine the last synchronization of the communication device with the infrastructure device based on the infrastructure device transmitting system information updates to the communication device, and / or the communication device may be configured to determine the last synchronization with the wireless communication network based on receiving system information from the wireless communication network.

[0107] In some arrangements of embodiments of the present technology, the UE may have recently performed mobility measurements. Sometimes the UE needs to perform mobility measurements. To perform mobility measurements, the UE / LP-WUR will need to be synchronized with the network (here, the measurements can be performed by the MR based on 5G NR signals, or can be performed by the LP-WUR based on LP-WUS signals, but in either case, the UE will be synchronized with the network). Therefore, the gNB does not need to send LP-WUS to re-synchronize the UE / LP-WUR, or the UE does not need to monitor such re-synchronization LP-WUS after transmitting the signals required for mobility measurements. In other words, the infrastructure device can be configured to determine that the communication device was last synchronized with the infrastructure device based on determining that the communication device has performed mobility measurements relative to the wireless communication network, and / or the communication device can be configured to determine that it was last synchronized with the wireless communication network based on performing mobility measurements relative to the wireless communication network.

[0108] In some arrangements of embodiments of the present technology, the gNB may have recently performed signaling / data transmission to the UE (where this may include RRC control signaling, or data, or control information via PDCCH or PDSCH, etc.), or the UE may have correspondingly recently performed transmission to the gNB. If the gNB has recently sent a signal to the UE (e.g., start / end RRC connection), then the UE will have recently been synchronized with the gNB, and the gNB will not need to send an LP-WUS signal to allow the UE to re-synchronize with the network, or the UE does not need to monitor such re-synchronization LP-WUS. In other words, the infrastructure device can be configured to determine that the communication device was last synchronized with the infrastructure device based on the infrastructure device transmitting control information and / or downlink data to the communication device, and / or the communication device can be configured to determine that it was last synchronized with the wireless communication network based on receiving control information and / or downlink data from the wireless communication network.

[0109] In some arrangements of embodiments of the present technology, if the UE determines that its clock may have drifted significantly, the UE can independently wake up its primary radio. If the UE / LP-WUR believes that its clock may have drifted significantly (and / or has not been synchronized for more than a threshold amount of time) or its LP-WUS monitoring window is too large, the LP-WUR can indicate that the UE's primary radio should wake up in order to resynchronize to the network. Once the UE's primary radio has been resynchronized, the start point of the LP-WUR's monitoring window can be reset, and the UE's primary radio can return to the sleep mode. In other words, a communication device can be configured to: determine that the communication device needs to synchronize with a wireless communication network based on determining that the clock of the communication device may have drifted in time by more than a threshold amount; switch the primary receiver to the on state; receive one or more synchronization signals from the wireless communication network via the primary receiver while the primary receiver is in the on state, where the one or more synchronization signals include timing information of the wireless communication network; synchronize the communication device (e.g., the primary receiver) with the wireless communication network based on the timing information of the wireless communication network; and switch the primary receiver to the off state. Here, the threshold amount can be fixed in the specification and known to the UE, indicated to the UE by the network in any suitable manner, or determined by the UE. Additionally, here, in the case where the primary receiver is first synchronized by the timing information indicated by the synchronization signal, before the MR returns to the off state, the communication device can also synchronize its low-power receiver based on the now-synchronized primary receiver to tell the current timing (where the clock of the LP-WUR can be automatically synchronized because it itself is derived from the clock of the MR).

[0110] Figure 11 A flowchart illustrating an example communication process in a communication system according to an embodiment of the present technology is shown. Figure 11 The process shown is a method of operating a communication device including a low-power receiver and a primary receiver (where the power consumption of the low-power receiver when it is in the on state is lower than the power consumption of the primary receiver when it is in the on state).

[0111] The method begins at step S1. The method includes, in step S2, determining whether the communication device is to monitor a first signal from the wireless communication network, where the first signal includes an indication of the timing information of the wireless communication network. In step S3, the method includes, if the communication device determines to monitor the first signal, receiving the first signal from the wireless communication network via the low-power receiver while the low-power receiver is in the on state and the primary receiver is in the off state. Then, in step S4, the process includes synchronizing the communication device (e.g., the low-power receiver of the communication device) with the wireless communication network based on the timing information of the wireless communication network. The process ends at step S4.

[0112] Those skilled in the art should understand that Figure 11 the method shown can be adjusted according to the embodiments of the present technology. For example, the method may include other intermediate steps, or these steps may be executed in any logical order. Although the embodiments of the present technology are mainly described through the example communication system shown Figure 10 those skilled in the art will understand that they can equally be applied to other systems similar to those described herein.

[0113] Those skilled in the art will further understand that such infrastructure devices and / or communication devices defined herein can be further defined according to the various settings and embodiments discussed in the previous paragraphs. Those skilled in the art will further understand that such infrastructure devices and communication devices as defined and described herein can form part of a communication system other than those defined in the present disclosure.

[0114] The following numbered paragraphs provide further example aspects and features of the present technology:

[0115] Paragraph 1. A method of operating a communication device including a low-power receiver and a main receiver, the method comprising:

[0116] determining whether the communication device is to monitor a first signal from a wireless communication network, wherein the first signal includes an indication of timing information of the wireless communication network;

[0117] if the communication device determines to monitor the first signal, receiving the first signal from the wireless communication network via the low-power receiver when the low-power receiver is in an on state and the main receiver is in an off state; and

[0118] synchronizing the communication device with the wireless communication network based on the timing information of the wireless communication network,

[0119] wherein the power consumption of the low-power receiver when it is in an on state is lower than the power consumption of the main receiver when it is in an on state.

[0120] Paragraph 2. The method according to paragraph 1, wherein the first signal is a low-power wake-up signal LP-WUS.

[0121] Paragraph 3. The method according to paragraph 2, wherein the LP-WUS indicates whether the main receiver should switch from an off state to an on state in response to the low-power receiver receiving the LP-WUS signal.

[0122] Paragraph 4. The method according to paragraph 2 or paragraph 3, wherein the LP-WUS includes: an indication of one or more communication device identifiers, and none of the one or more indicated communication device identifiers match the identifier of the communication device.

[0123] Paragraph 5. The method according to any one of paragraphs 2 to 4, wherein the LP-WUS signal is received from a wireless communication network as a broadcast signal broadcast to the communication device and to one or more other communication devices, and wherein the broadcast LP-WUS includes: an indication that the primary receiver will not switch from the off state to the on state in response to the low power receiver receiving the broadcast LP-WUS signal.

[0124] Paragraph 6. The method according to any one of paragraphs 1 to 5, wherein the indication of the timing information of the wireless communication network includes: a sequence of one or more bits, the sequence of one or more bits indicating a time index of a first signal within a transmission window during which the first signal can be transmitted by the wireless communication network.

[0125] Paragraph 7. The method according to paragraph 6, wherein the time index of the first signal within the transmission window is the start position of the first signal within the transmission window.

[0126] Paragraph 8. The method according to paragraph 6 or paragraph 7, wherein the time index of the first signal within the transmission window is the end position of the first signal within the transmission window.

[0127] Paragraph 9. The method according to any one of paragraphs 6 to 8, wherein the transmission window includes a plurality of possible positions of the first signal, and wherein the time index of the first signal within the transmission window is one of the plurality of possible positions of the first signal, wherein the first signal is transmitted by the wireless communication network.

[0128] Paragraph 10. The method according to any one of paragraphs 1 to 9, wherein the indication of the timing information of the wireless communication network includes: a sequence of one or more bits, the sequence of one or more bits indicating a time index of the first signal relative to a paging occasion associated with the communication device.

[0129] Paragraph 11. The method according to any one of paragraphs 1 to 10, wherein the indication of the timing information of the wireless communication network includes: a synchronization sequence used by the wireless communication network when transmitting the first signal, and wherein the synchronization sequence is one of a plurality of possible synchronization sequences, each of the plurality of possible synchronization sequences being associated with one of the plurality of possible positions of the first signal within the transmission window.

[0130] Paragraph 12. The method according to any one of paragraphs 1 to 11, includes:

[0131] determining that the first signal will be transmitted by the wireless communication network at a specific time, and

[0132] monitoring the first signal at the specific time.

[0133] Paragraph 13. The method according to any one of paragraphs 1 to 12, comprising:

[0134] determining that a first signal is to be transmitted by a wireless communication network within a specified time period, and

[0135] monitoring the first signal during the specified time period.

[0136] Paragraph 14. The method according to any one of paragraphs 1 to 13, wherein the first signal includes an indication of a cell of the wireless communication network transmitting the first signal.

[0137] Paragraph 15. The method according to any one of paragraphs 1 to 14, wherein the communication device determines whether the communication device is to monitor the first signal based on the clock accuracy of the communication device.

[0138] Paragraph 16. The method according to any one of paragraphs 1 to 15, wherein the communication device determines whether the communication device is to monitor the first signal based on the length of time since the communication device last synchronized with the wireless communication network.

[0139] Paragraph 17. The method according to paragraph 16, wherein the communication device determines the last synchronization with the wireless communication network based on receiving system information from the wireless communication network.

[0140] Paragraph 18. The method according to paragraph 16 or paragraph 17, wherein the communication device determines the last synchronization with the wireless communication network based on performing mobility measurements relative to the wireless communication network.

[0141] Paragraph 19. The method according to any one of paragraphs 16 to 18, wherein the communication device determines the last synchronization with the wireless communication network based on receiving control information and / or downlink data from the wireless communication network.

[0142] Paragraph 20. A communication device, comprising:

[0143] a low-power receiver,

[0144] a main receiver, and

[0145] at least one controller configured to control the communication device to:

[0146] determine whether the communication device is to monitor a first signal from the wireless communication network, wherein the first signal includes an indication of timing information of the wireless communication network;

[0147] if the communication device determines to monitor the first signal, receive the first signal from the wireless communication network via the low-power receiver when the low-power receiver is in an on state and the main receiver is in an off state; and

[0148] Synchronize a communication device with a wireless communication network based on timing information of the wireless communication network

[0149] wherein, when the low-power receiver is in an on state, the power consumption of the low-power receiver is lower than the power consumption of the main receiver when the main receiver is in an on state.

[0150] Paragraph 21. A circuit for a communication device, comprising:

[0151] A low-power receiver circuit

[0152] A main receiver circuit, and

[0153] At least one controller circuit, the at least one controller circuit being configured to control the communication device to:

[0154] Determine whether the communication device is to monitor a first signal from the wireless communication network, wherein the first signal includes an indication of timing information of the wireless communication network;

[0155] If the communication device determines to monitor the first signal, receive the first signal from the wireless communication network via the low-power receiver when the low-power receiver is in an on state and the main receiver is in an off state; and

[0156] Synchronize the communication device with the wireless communication network based on the timing information of the wireless communication network

[0157] wherein, when the low-power receiver is in an on state, the power consumption of the low-power receiver is lower than the power consumption of the main receiver when the main receiver is in an on state.

[0158] Paragraph 22. A method of operating an infrastructure device forming part of a wireless communication network, the method comprising:

[0159] Determine whether a communication device needs to be synchronized with the infrastructure device, and

[0160] If the infrastructure device determines that the communication device needs to be synchronized with the infrastructure device, transmit a first signal to the communication device, the first signal including an indication of timing information of the infrastructure device for the communication device to use to synchronize the communication device with the infrastructure device based on the timing information of the infrastructure device

[0161] wherein the method includes transmitting the first signal to the low-power receiver of the communication device when the low-power receiver of the communication device is in an on state and the main receiver of the communication device is in an off state, and wherein the power consumption of the low-power receiver of the communication device is lower than the power consumption of the main receiver of the communication device when the low-power receiver of the communication device is in an on state.

[0162] Paragraph 23. The method according to paragraph 22, wherein the first signal is a low-power wake-up signal LP-WUS.

[0163] Paragraph 24. The method according to paragraph 23, wherein the LP-WUS indicates whether the communication device should switch the main receiver of the communication device from the off state to the on state in response to the low-power receiver receiving the LP-WUS signal.

[0164] Paragraph 25. The method according to paragraph 23 or paragraph 24, wherein the LP-WUS includes: an indication of one or more communication device identifiers, and wherein none of the one or more indicated communication device identifiers match the identifier of the communication device or the identifiers of one or more other communication devices to which the infrastructure device transmits the LP-WUS.

[0165] Paragraph 26. The method according to any one of paragraphs 23 to 25, wherein the LP-WUS indicates that the communication device should switch the main receiver of the communication device from the off state to the on state in response to the low-power receiver receiving the LP-WUS signal, and wherein the method includes:

[0166] Transmitting the LP-WUS to the communication device and one or more other communication devices according to a cyclic schedule determined by the infrastructure device.

[0167] Paragraph 27. The method according to any one of paragraphs 23 to 26, including:

[0168] Broadcasting the LP-WUS signal to the communication device and to one or more other communication devices, each communication device including a low-power receiver and a main receiver, wherein the broadcast LP-WUS includes: an indication that the communication device and one or more other communication devices should not switch the main receiver of the communication device from the off state to the on state in response to receiving the broadcast LP-WUS signal.

[0169] Paragraph 28. The method according to any one of paragraphs 22 to 27, wherein the indication of the timing information of the infrastructure device includes: a sequence of one or more bits, the sequence of one or more bits indicating the time index of the first signal within a transmission window during which the first signal can be transmitted by the infrastructure device.

[0170] Paragraph 29. The method according to paragraph 28, wherein the time index of the first signal within the transmission window is the start position of the first signal within the transmission window.

[0171] Paragraph 30. The method according to paragraph 28 or paragraph 29, wherein the time index of the first signal within the transmission window is the end position of the first signal within the transmission window.

[0172] Paragraph 31. The method according to any one of paragraphs 28 to 30, wherein the transmission window includes a plurality of possible positions of the first signal, and wherein the time index of the first signal within the transmission window is one of the plurality of possible positions of the first signal, and wherein the first signal is transmitted by an infrastructure device.

[0173] Paragraph 32. The method according to any one of paragraphs 22 to 31, wherein the indication of the timing information of the infrastructure device includes: a sequence of one or more bits, the sequence of one or more bits indicating the time index of the first signal relative to a paging occasion associated with the communication device.

[0174] Paragraph 33. The method according to any one of paragraphs 22 to 32, wherein the indication of the timing information of the infrastructure device includes: a synchronization sequence used by the infrastructure device when transmitting the first signal, and wherein the synchronization sequence is one of a plurality of possible synchronization sequences, each of the plurality of possible synchronization sequences being associated with one of the plurality of possible positions of the first signal within the transmission window.

[0175] Paragraph 34. The method according to any one of paragraphs 22 to 33, comprising:

[0176] Transmitting the first signal at a specific time known to the communication device.

[0177] Paragraph 35. The method according to paragraph 34, comprising:

[0178] Receiving, when the communication device is in a connected state with the infrastructure device, capability information of the communication device, wherein the capability information of the communication device includes an indication of a maximum offset rate of the clock of the communication device, and

[0179] Determining the specific time based on the maximum offset rate of the clock of the communication device.

[0180] Paragraph 36. The method according to any one of paragraphs 22 to 35, comprising:

[0181] Transmitting the first signal within a specified time period known to the communication device.

[0182] Paragraph 37. The method according to any one of paragraphs 22 to 36, wherein the first signal includes an indication of a cell of a wireless communication network, the cell being a cell controlled by the infrastructure device.

[0183] Paragraph 38. The method according to any one of paragraphs 22 to 37, wherein the infrastructure device determines whether the communication device needs to synchronize with the infrastructure device based on the length of time since the communication device last synchronized with the infrastructure device, and wherein the method includes:

[0184] If the infrastructure device determines that the communication device does not need to synchronize with the infrastructure device, it determines that the infrastructure device will skip the transmission of the first signal to the communication device.

[0185] Paragraph 39. The method according to paragraph 38, wherein the infrastructure device determines the last synchronization of the communication device with the infrastructure device based on the infrastructure device transmitting system information to the communication device.

[0186] Paragraph 40. The method according to paragraph 38 or paragraph 39, wherein the infrastructure device determines the last synchronization of the communication device with the infrastructure device based on determining that the communication device has performed mobility measurements with respect to the wireless communication network.

[0187] Paragraph 41. The method according to any one of paragraphs 38 to 40, wherein the infrastructure device determines the last synchronization of the communication device with the infrastructure device based on the infrastructure device transmitting control information and / or downlink data to the communication device.

[0188] Paragraph 42. An infrastructure device forming part of a wireless communication network, the infrastructure device comprising:

[0189] a transceiver circuit, and

[0190] a controller circuit, the controller circuit being configured in combination with the transceiver circuit to:

[0191] determine whether the communication device needs to synchronize with the infrastructure device, and

[0192] if the infrastructure device determines that the communication device needs to synchronize with the infrastructure device, transmit a first signal to the communication device, the first signal including an indication of the timing information of the infrastructure device for the communication device to use to synchronize the communication device with the infrastructure device based on the timing information of the infrastructure device,

[0193] wherein the method includes transmitting the first signal to the low-power receiver of the communication device when the low-power receiver of the communication device is in an on state and the main receiver of the communication device is in an off state, and wherein the power consumption of the low-power receiver of the communication device when the low-power receiver is in an on state is lower than the power consumption of the main receiver of the communication device when the main receiver of the communication device is in an on state.

[0194] Paragraph 43. A circuit for an infrastructure device forming part of a wireless communication network, the infrastructure device comprising:

[0195] a transceiver circuit, and

[0196] a controller circuit, the controller circuit being configured in combination with the transceiver circuit to:

[0197] Determine whether the communication device needs to synchronize with the infrastructure device, and

[0198] If the infrastructure device determines that the communication device needs to synchronize with the infrastructure device, transmit a first signal to the communication device, the first signal including an indication of the timing information of the infrastructure device, for the communication device to use to synchronize the communication device with the infrastructure device based on the timing information of the infrastructure device,

[0199] wherein, the method includes transmitting the first signal to the low-power receiver of the communication device when the low-power receiver of the communication device is in the on state and the main receiver of the communication device is in the off state, and wherein, the power consumption of the low-power receiver of the communication device when the low-power receiver is in the on state is lower than the power consumption of the main receiver of the communication device when the main receiver of the communication device is in the on state.

[0200] Paragraph 44. A wireless communication system includes the communication device according to paragraph 20 and the infrastructure device according to paragraph 42.

[0201] Paragraph 45. A computer program including instructions that, when loaded onto a computer, cause the computer to perform the method according to any one of paragraphs 1 to 19 or any one of paragraphs 22 to 41.

[0202] Paragraph 46. A non-transitory computer-readable storage medium storing the computer program according to paragraph 45.

[0203] Paragraph 47. A method of operating a communication device including a low-power receiver and a main receiver, the method including:

[0204] Based on determining that the clock of the communication device has been offset in time by more than a threshold amount, determine that the communication device needs to synchronize with the wireless communication network,

[0205] Switch the main receiver to the on state,

[0206] When the main receiver is in the on state, receive one or more synchronization signals from the wireless communication network via the main receiver, wherein, the one or more synchronization signals include the timing information of the wireless communication network,

[0207] Based on the timing information of the wireless communication network, synchronize the communication device with the wireless communication network, and

[0208] Switch the main receiver to the off state,

[0209] wherein, the power consumption of the low-power receiver when the low-power receiver is in the on state is lower than the power consumption of the main receiver when the main receiver is in the on state.

[0210] Paragraph 48. A communication device, comprising:

[0211] A low-power receiver,

[0212] A main receiver, and

[0213] At least one controller, the at least one controller being configured to control the communication device to:

[0214] Determine that the communication device needs to synchronize with a wireless communication network based on determining that the clock of the communication device has been offset in time by more than a threshold amount,

[0215] Switch the main receiver to an on state,

[0216] When the main receiver is in the on state, receive one or more synchronization signals from the wireless communication network via the main receiver, wherein the one or more synchronization signals include timing information of the wireless communication network,

[0217] Synchronize the communication device with the wireless communication network based on the timing information of the wireless communication network, and

[0218] Switch the main receiver to an off state,

[0219] Wherein the power consumption of the low-power receiver when the low-power receiver is in the on state is lower than the power consumption of the main receiver when the main receiver is in the on state.

[0220] Paragraph 49. A circuit for a communication device, comprising:

[0221] A low-power receiver circuit,

[0222] A main receiver circuit, and

[0223] At least one controller circuit, the at least one controller circuit being configured to control the communication device to:

[0224] Determine that the communication device needs to synchronize with a wireless communication network based on determining that the clock of the communication device has been offset in time by more than a threshold amount,

[0225] Switch the main receiver to an on state,

[0226] When the main receiver is in the on state, receive one or more synchronization signals from the wireless communication network via the main receiver, wherein the one or more synchronization signals include timing information of the wireless communication network,

[0227] Synchronize the communication device with the wireless communication network based on the timing information of the wireless communication network, and

[0228] Switch the main receiver to an off state,

[0229] Among them, when the low-power receiver is in the on state, the power consumption of the low-power receiver is lower than that of the main receiver when the main receiver is in the on state.

[0230] Paragraph 50. A computer program comprising instructions that, when loaded onto a computer, cause the computer to perform the method according to Paragraph 47.

[0231] Paragraph 51. A non-transitory computer-readable storage medium storing the computer program according to Paragraph 50.

[0232] Paragraph 52. A method of operating an infrastructure device forming part of a wireless communication network, the method comprising:

[0233] Periodically transmitting a first signal to one or more communication devices, the first signal including an indication of timing information of the infrastructure device for use by the one or more communication devices to synchronize the one or more communication devices with the infrastructure device based on the timing information of the infrastructure device,

[0234] wherein the method includes periodically transmitting the first signal to the low-power receiver of each of the one or more communication devices when the low-power receiver of each communication device is in the on state and the main receiver of each communication device is in the off state, and wherein the power consumption of the low-power receiver of each communication device is lower when the low-power receiver of each communication device is in the on state than the power consumption of the main receiver of each communication device when the main receiver of each communication device is in the on state.

[0235] Paragraph 53. An infrastructure device forming part of a wireless communication network, the infrastructure device comprising:

[0236] Transceiver circuitry, and

[0237] Controller circuitry configured in combination with the transceiver circuitry to:

[0238] Periodically transmit a first signal to one or more communication devices, the first signal including an indication of timing information of the infrastructure device for use by the one or more communication devices to synchronize the one or more communication devices with the infrastructure device based on the timing information of the infrastructure device,

[0239] wherein the method includes periodically transmitting the first signal to the low-power receiver of each of the one or more communication devices when the low-power receiver of each communication device is in the on state and the main receiver of each communication device is in the off state, and wherein the power consumption of the low-power receiver of each communication device is lower when the low-power receiver of each communication device is in the on state than the power consumption of the main receiver of each communication device when the main receiver of each communication device is in the on state.

[0240] Paragraph 54. The circuitry of infrastructure equipment forming part of a wireless communication network, the infrastructure equipment comprising:

[0241] a transceiver circuitry, and

[0242] a controller circuitry, the controller circuitry being configured in combination with the transceiver circuitry to:

[0243] periodically transmit a first signal to one or more communication devices, the first signal including an indication of timing information of the infrastructure equipment for use by the one or more communication devices to synchronize the one or more communication devices with the infrastructure equipment based on the timing information of the infrastructure equipment,

[0244] wherein the method includes periodically transmitting the first signal to a low-power receiver of each of the one or more communication devices when the low-power receiver of each communication device is in an on state and the main receiver of each communication device is in an off state and wherein the power consumption of the low-power receiver of each communication device is lower when the low-power receiver of each communication device is in an on state than the power consumption of the main receiver of each communication device when the main receiver of each communication device is in an on state.

[0245] Paragraph 55. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform the method according to Paragraph 52.

[0246] Paragraph 56. A non-transitory computer-readable storage medium storing the computer program according to Paragraph 55.

[0247] It should be understood that, for clarity, the above description has described embodiments with reference to different functional units, circuitry and / or processors. However, it will be apparent that any suitable distribution of functionality between different functional units, circuitry and / or processors may be used without departing from the embodiments.

[0248] The described embodiments may be implemented in any suitable form, including hardware, software, firmware, or any combination thereof. The described embodiments may optionally be implemented at least in part as computer software running on one or more data processors and / or digital signal processors. The elements and components of any embodiment may be physically, functionally and logically implemented in any suitable manner. Indeed, the functionality may be implemented in a single unit, multiple units, or as part of other functional units. Thus, the disclosed embodiments may be implemented in a single unit, or may be physically and functionally distributed between different units, circuitry and / or processors.

[0249] Although the present disclosure has been described in connection with some embodiments, the present disclosure is not intended to be limited to the specific forms set forth herein. Additionally, although a feature may appear to be described in connection with a particular embodiment, those skilled in the art will recognize that the various features of the described embodiments can be combined in any manner suitable for implementing the technology.

[0250] References

[0251] [1] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based radio access”, John Wiley and Sons, 2009.

[0252] [2] TR 38.913, “3 rd Generation Partnership Project; Technical Specification Group Radio Access Network; Study on Scenarios and Requirements for Next Generation Access Technologies (Release 14)”, 3GPP, v14.3.0, August 2017.

[0253] [3] Rl-1708311, “Idle Mode Power Efficiency Reduction,” Sierra Wireless, RAN 1#89.

[0254] [4] TR 38.840, “NR: Study on UE Power Saving (Release 16, v0.1.0)”, 3GPP, November 2018.

[0255] [5] RP-222644, “Revised SID: Study on low-power Wake-up Signal and Receiver for NR”, RANP#97e, September 2022.

Claims

1. A method of operating a communication device including a low-power receiver and a main receiver, the method comprises: determining whether the communication device is to monitor a first signal from a wireless communication network, wherein the first signal includes an indication of timing information of the wireless communication network; if the communication device determines to monitor the first signal, when the low-power receiver is in an on state and the main receiver is in an off state, receiving the first signal from the wireless communication network via the low-power receiver; and synchronizing the communication device with the wireless communication network based on the timing information of the wireless communication network, wherein the power consumption of the low-power receiver is lower when the low-power receiver is in the on state than the power consumption of the main receiver when the main receiver is in the on state.

2. The method according to claim 1, wherein, the first signal is a low-power wake-up signal LP-WUS.

3. The method according to claim 2, wherein, the LP-WUS indicates whether the main receiver should switch from the off state to the on state in response to the low-power receiver receiving the LP-WUS signal.

4. The method according to claim 2, wherein, the LP-WUS includes: an indication of one or more communication device identifiers, and none of the one or more indicated communication device identifiers match the identifier of the communication device.

5. The method according to claim 2, wherein, the LP-WUS signal is received from the wireless communication network as a broadcast signal broadcast to the communication device and to one or more other communication devices, wherein the broadcast LP-WUS includes: an indication that the main receiver does not switch from the off state to the on state in response to the low-power receiver receiving the broadcast LP-WUS signal.

6. The method according to claim 1, wherein, the indication of the timing information of the wireless communication network includes: a sequence of one or more bits indicating a time index of the first signal within a transmission window in which the first signal can be transmitted by the wireless communication network.

7. The method according to claim 6, wherein, the time index of the first signal within the transmission window is the start position of the first signal within the transmission window.

8. The method according to claim 6, wherein, the time index of the first signal within the transmission window is the end position of the first signal within the transmission window.

9. The method according to claim 6, wherein, the transmission window includes multiple possible positions of the first signal, and the time index of the first signal within the transmission window is one of the multiple possible positions of the first signal, wherein the first signal is transmitted by the wireless communication network.

10. The method according to claim 1, wherein, The indication of the timing information of the wireless communication network includes: a sequence of one or more bits indicating a time index of the first signal relative to a paging occasion associated with the communication device.

11. The method according to claim 1, wherein, the indication of the timing information of the wireless communication network includes: a synchronization sequence used by the wireless communication network when transmitting the first signal, and wherein the synchronization sequence is one of a plurality of possible synchronization sequences, and each of the plurality of possible synchronization sequences is associated with one of a plurality of possible positions of the first signal within a transmission window.

12. The method according to claim 1, including: determining that the first signal will be transmitted by the wireless communication network at a specific time, and monitoring the first signal at the specific time.

13. The method according to claim 1, including: determining that the first signal will be transmitted by the wireless communication network within a specified time period, and monitoring the first signal during the specified time period.

14. The method according to claim 1, wherein, the first signal includes: an indication of a cell of the wireless communication network transmitting the first signal.

15. The method according to claim 1, wherein, the communication device determines whether the communication device is to monitor the first signal based on the clock accuracy of the communication device.

16. The method according to claim 1, wherein, the communication device determines whether the communication device is to monitor the first signal based on the length of time since the communication device last synchronized with the wireless communication network.

17. The method according to claim 16, wherein, the communication device determines the last synchronization of the communication device with the wireless communication network based on receiving system information from the wireless communication network.

18. The method according to claim 16, wherein, the communication device determines the last synchronization of the communication device with the wireless communication network based on performing mobility measurements relative to the wireless communication network.

19. The method according to claim 16, wherein, the communication device determines the last synchronization of the communication device with the wireless communication network based on receiving control information and / or downlink data from the wireless communication network.

20. A communication device, including: a low-power receiver, a main receiver, and at least one controller configured to control the communication device to: determine whether the communication device is to monitor a first signal from a wireless communication network, wherein the first signal includes an indication of the timing information of the wireless communication network; if the communication device determines to monitor the first signal, receive the first signal from the wireless communication network via the low-power receiver when the low-power receiver is in an on state and the main receiver is in an off state; and synchronize the communication device with the wireless communication network based on the timing information of the wireless communication network, Wherein, when the low-power receiver is in the on state, the power consumption of the low-power receiver is lower than that of the main receiver when the main receiver is in the on state.

21. A circuit for a communication device, comprising: a low-power receiver circuit, a main receiver circuit, and at least one controller circuit configured to control the communication device to: determine whether the communication device is to monitor a first signal from a wireless communication network, wherein the first signal includes an indication of timing information of the wireless communication network; if the communication device determines to monitor the first signal, receive the first signal from the wireless communication network via the low-power receiver when the low-power receiver is in the on state and the main receiver is in the off state; and synchronize the communication device with the wireless communication network based on the timing information of the wireless communication network, wherein, when the low-power receiver is in the on state, the power consumption of the low-power receiver is lower than that of the main receiver when the main receiver is in the on state.

22. A method of operating an infrastructure device forming part of a wireless communication network, the method comprising: determining whether a communication device needs to synchronize with the infrastructure device, and if the infrastructure device determines that the communication device needs to synchronize with the infrastructure device, transmitting a first signal to the communication device, the first signal including an indication of timing information of the infrastructure device for the communication device to synchronize the communication device with the infrastructure device based on the timing information of the infrastructure device, wherein the method includes transmitting the first signal to the low-power receiver of the communication device when the low-power receiver of the communication device is in the on state and the main receiver of the communication device is in the off state, and wherein, when the low-power receiver of the communication device is in the on state, the power consumption of the low-power receiver of the communication device is lower than that of the main receiver of the communication device when the main receiver of the communication device is in the on state.

23. The method according to claim 22, wherein, the first signal is a low-power wake-up signal LP-WUS.

24. The method according to claim 23, wherein, the LP-WUS indicates whether the communication device should switch the main receiver of the communication device from the off state to the on state in response to the low-power receiver receiving the LP-WUS signal.

25. The method according to claim 23, wherein, the LP-WUS includes: an indication of one or more communication device identifiers, and wherein none of the one or more indicated communication device identifiers match the identifier of the communication device or the identifiers of one or more other communication devices, and the infrastructure device transmits the LP-WUS to one or more other communication devices.

26. The method according to claim 23, wherein, The LP-WUS instructs the communication device to switch the main receiver of the communication device from the off state to the on state in response to the low-power receiver receiving the LP-WUS signal, and wherein the method comprises: Transmitting the LP-WUS to the communication device and one or more other communication devices according to a cyclic schedule determined by the infrastructure device.

27. The method according to claim 23, comprising: Broadcasting the LP-WUS signal to the communication device and to one or more other communication devices, each of the one or more other communication devices including a low-power receiver and a main receiver, wherein the broadcast LP-WUS comprises: an indication that the communication device and the one or more other communication devices do not switch the main receiver of the communication device from the off state to the on state in response to receiving the broadcast LP-WUS signal.

28. The method according to claim 22, wherein, the indication of the timing information of the infrastructure device comprises: a sequence of one or more bits indicating a time index of the first signal within a transmission window in which the first signal can be transmitted by the infrastructure device.

29. The method according to claim 28, wherein, the time index of the first signal within the transmission window is the start position of the first signal within the transmission window.

30. The method according to claim 28, wherein, the time index of the first signal within the transmission window is the end position of the first signal within the transmission window.

31. The method according to claim 28, wherein, the transmission window includes a plurality of possible positions of the first signal, and wherein the time index of the first signal within the transmission window is one of the plurality of possible positions of the first signal, wherein the first signal is transmitted by the infrastructure device.

32. The method according to claim 22, wherein, the indication of the timing information of the infrastructure device comprises: a sequence of one or more bits indicating a time index of the first signal relative to a paging occasion associated with the communication device.

33. The method according to claim 22, wherein, the indication of the timing information of the infrastructure device comprises: a synchronization sequence used by the infrastructure device when transmitting the first signal, and wherein the synchronization sequence is one of a plurality of possible synchronization sequences, each of the plurality of possible synchronization sequences being associated with one of a plurality of possible positions of the first signal within a transmission window.

34. The method according to claim 22, comprising: Transmitting the first signal at a specific time known to the communication device.

35. The method according to claim 34, comprising: When the communication device is in a connected state with the infrastructure device, receive capability information of the communication device, wherein the capability information of the communication device includes an indication of a maximum offset rate of a clock of the communication device, and determine the specific time based on the maximum offset rate of the clock of the communication device.

36. The method according to claim 22, comprising: transmit the first signal within a specified time period known to the communication device.

37. The method according to claim 22, wherein, the first signal includes: an indication of a cell of the wireless communication network, the cell being a cell controlled by the infrastructure device.

38. The method according to claim 22, wherein, the infrastructure device determines whether the communication device needs to synchronize with the infrastructure device based on a length of time since the communication device last synchronized with the infrastructure device, and wherein the method includes: if the infrastructure device determines that the communication device does not need to synchronize with the infrastructure device, determine that the infrastructure device will skip transmission of the first signal to the communication device.

39. The method according to claim 38, wherein, the infrastructure device determines the last synchronization of the communication device with the infrastructure device based on the infrastructure device transmitting system information to the communication device.

40. The method according to claim 38, wherein, the infrastructure device determines the last synchronization of the communication device with the infrastructure device based on determining that the communication device has performed mobility measurements with respect to the wireless communication network.

41. The method according to claim 38, wherein, the infrastructure device determines the last synchronization of the communication device with the infrastructure device based on the infrastructure device transmitting control information and / or downlink data to the communication device.

42. An infrastructure device forming part of a wireless communication network, the infrastructure device comprising: a transceiver circuit, and a controller circuit configured in combination with the transceiver circuit to: determine whether a communication device needs to synchronize with the infrastructure device, and if the infrastructure device determines that the communication device needs to synchronize with the infrastructure device, transmit a first signal to the communication device, the first signal including an indication of timing information of the infrastructure device for the communication device to use to synchronize the communication device with the infrastructure device based on the timing information of the infrastructure device, wherein the method includes transmitting the first signal to a low-power receiver of the communication device when the low-power receiver of the communication device is in an on state and a main receiver of the communication device is in an off state, and wherein power consumption of the low-power receiver of the communication device is lower when the low-power receiver of the communication device is in the on state than power consumption of the main receiver of the communication device when the main receiver of the communication device is in the on state.

43. A circuit for an infrastructure device forming part of a wireless communication network, the infrastructure device comprising: a transceiver circuit, and a controller circuit configured in combination with the transceiver circuit to: determine whether a communication device needs to synchronize with the infrastructure device, and if the infrastructure device determines that the communication device needs to synchronize with the infrastructure device, transmit a first signal to the communication device, the first signal including an indication of timing information of the infrastructure device for the communication device to use to synchronize the communication device with the infrastructure device based on the timing information of the infrastructure device, wherein the method includes transmitting the first signal to the low-power receiver of the communication device when the low-power receiver of the communication device is in an on state and the main receiver of the communication device is in an off state, and wherein the power consumption of the low-power receiver of the communication device is lower when the low-power receiver of the communication device is in the on state than the power consumption of the main receiver of the communication device when the main receiver of the communication device is in the on state.

44. A wireless communication system comprising the communication device according to claim 20 and the infrastructure device according to claim 42.

45. A computer program comprising instructions that, when loaded onto a computer, cause the computer to perform the method according to claim 1 or claim 22.

46. A non-transitory computer-readable storage medium storing the computer program according to claim 45.

47. A method of operating a communication device including a low-power receiver and a main receiver, the method comprising: determining that the communication device needs to synchronize with a wireless communication network based on determining that the clock of the communication device has been offset in time by more than a threshold amount, switching the main receiver to an on state, when the main receiver is in the on state, receiving one or more synchronization signals from the wireless communication network via the main receiver, wherein the one or more synchronization signals include timing information of the wireless communication network, synchronizing the communication device with the wireless communication network based on the timing information of the wireless communication network, and switching the main receiver to an off state, wherein the power consumption of the low-power receiver is lower when the low-power receiver is in the on state than the power consumption of the main receiver when the main receiver is in the on state.

48. A communication device, comprising: a low-power receiver, a main receiver, and at least one controller configured to control the communication device to: determine that the communication device needs to synchronize with a wireless communication network based on determining that the clock of the communication device has been offset in time by more than a threshold amount, switch the main receiver to an on state, when the main receiver is in the on state, receive one or more synchronization signals from the wireless communication network via the main receiver, wherein the one or more synchronization signals include timing information of the wireless communication network, Synchronize the communication device with the wireless communication network based on the timing information of the wireless communication network, and Switch the main receiver to the off state, wherein the power consumption of the low-power receiver when the low-power receiver is in the on state is lower than the power consumption of the main receiver when the main receiver is in the on state.

49. A circuit for a communication device, comprising: a low-power receiver circuit, a main receiver circuit, and at least one controller circuit configured to control the communication device to: Determine that the communication device needs to be synchronized with a wireless communication network based on determining that the clock of the communication device has drifted in time by more than a threshold amount, Switch the main receiver to the on state, When the main receiver is in the on state, receive one or more synchronization signals from the wireless communication network via the main receiver, wherein the one or more synchronization signals include timing information of the wireless communication network, Synchronize the communication device with the wireless communication network based on the timing information of the wireless communication network, and Switch the main receiver to the off state, wherein the power consumption of the low-power receiver when the low-power receiver is in the on state is lower than the power consumption of the main receiver when the main receiver is in the on state.

50. A computer program comprising instructions that, when loaded onto the computer, cause the computer to perform the method according to claim 47.

51. A non-transitory computer-readable storage medium storing the computer program according to claim 50.

52. A method of operating an infrastructure device forming part of a wireless communication network, the method comprising: Periodically transmit a first signal to one or more communication devices, the first signal including an indication of the timing information of the infrastructure device for use by the one or more communication devices to synchronize the one or more communication devices with the infrastructure device based on the timing information of the infrastructure device, wherein the method includes periodically transmitting the first signal to the low-power receiver of each of the one or more communication devices when the low-power receiver of each communication device is in the on state and the main receiver of each communication device is in the off state, and wherein the power consumption of the low-power receiver of each communication device when the low-power receiver of each communication device is in the on state is lower than the power consumption of the main receiver of each communication device when the main receiver of each communication device is in the on state.

53. An infrastructure device forming part of a wireless communication network, the infrastructure device comprising: a transceiver circuit, and a controller circuit configured in combination with the transceiver circuit to: Periodically transmit a first signal to one or more communication devices, the first signal including an indication of timing information of the infrastructure device for the one or more communication devices to synchronize the one or more communication devices with the infrastructure device based on the timing information of the infrastructure device. Wherein, the method includes periodically transmitting the first signal to the low-power receiver of each of the one or more communication devices when the low-power receiver of each communication device is in an on state and the main receiver of each communication device is in an off state, and wherein the power consumption of the low-power receiver of each communication device is lower when the low-power receiver of each communication device is in the on state than the power consumption of the main receiver of each communication device when the main receiver of each communication device is in the on state.

54. A circuit of an infrastructure device forming part of a wireless communication network, the infrastructure device comprising: a transceiver circuit, and a controller circuit configured in combination with the transceiver circuit to: Periodically transmit a first signal to one or more communication devices, the first signal including an indication of timing information of the infrastructure device for the one or more communication devices to synchronize the one or more communication devices with the infrastructure device based on the timing information of the infrastructure device. Wherein, the method includes periodically transmitting the first signal to the low-power receiver of each of the one or more communication devices when the low-power receiver of each communication device is in an on state and the main receiver of each communication device is in an off state and wherein the power consumption of the low-power receiver of each communication device is lower when the low-power receiver of each communication device is in the on state than the power consumption of the main receiver of each communication device when the main receiver of each communication device is in the on state.

55. A computer program comprising instructions that, when loaded onto a computer, cause the computer to perform the method according to claim 52.

56. A non-transitory computer-readable storage medium storing the computer program according to claim 55.

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