Network device, terminal device, and method implemented in the network device and terminal device

Abstract

Embodiments of the present disclosure relate to a method and apparatus for wake-up signals. The method implemented in a network device includes forming an OOK subsequence with a plurality of OOK symbols including at least one OOK on-symbol and at least one OOK off-symbol. The plurality of OOK symbols are associated with one OFDM symbol. The method further includes mapping the OOK subsequence to a plurality of pre-discrete Fourier transform (pre-DFT) subsequences respectively to form a pre-DFT sequence, and performing transform precoding on the pre-DFT sequence. The method further includes mapping the output of the transform precoding to a frequency region assigned to a wake-up signal (WUS) to generate the WUS, and transmitting the WUS to a terminal device.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to the field of telecommunications, and more particularly, to methods and apparatuses for wake-up signals.

Background Art

[0002] For user equipment (UE) in the radio resource control (RRC) idle / inactive state, periodic paging monitoring and measurement consume a significant amount of power on the UE side. This is important for power-constrained devices such as Internet of Things (IoT) devices and wearable devices.

[0003] There is a need for research on low-power wake-up signals (WUS) that can study and evaluate low-power signal and low-power receiver technologies to achieve ultra-low power consumption and low wake-up latency.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, exemplary embodiments of the present disclosure provide methods and apparatuses for wake-up signals.

Means for Solving the Problems

[0005] In a first aspect, a method implemented in a network device is provided. The method includes generating at least one on-off keying (OOK) on symbol using a first number of frequency resources mapped with non-zero values, where the non-zero values are used for normal downlink (DL) transmission. The method further includes generating at least one OOK off symbol using a second number of frequency resources mapped with zero values or values near zero. The method further includes generating a wake-up signal (WUS) based on the at least one OOK on symbol and the at least one OOK off symbol, and transmitting the WUS to a terminal device.

[0006] In a second aspect, a method implemented in a network device is provided. The method includes forming an OOK sub-sequence with a plurality of OOK symbols including at least one OOK on symbol and at least one OOK off symbol, where the plurality of OOK symbols are associated with one OFDM symbol. The method further includes mapping the OOK sub-sequence to a plurality of pre-discrete Fourier transform (pre-DFT) sub-sequences respectively to form a pre-DFT sequence. The method further includes performing transform precoding on the pre-DFT sequence, and mapping an output of the transform precoding to frequency resources assigned to a wake-up signal (WUS) to generate the WUS. The method further includes transmitting the WUS to a terminal device. The length of the pre-DFT sub-sequence among the plurality of pre-DFT sub-sequences is associated with at least one of the number of sub-carriers used for the WUS, the number of the plurality of OOK symbols, or the index of the pre-DFT sub-sequence among the plurality of pre-DFT sub-sequences.

[0007] In a third aspect, a method implemented in a terminal device is provided. The method includes receiving a wake-up signal (WUS) from a network device. The method further includes detecting the WUS and determining a plurality of on-off keying (OOK) symbols including at least one OOK on-symbol and at least one OOK off-symbol. The at least one OOK on-symbol is generated based on a first number of frequency resources mapped with non-zero values. The non-zero values are used for normal downlink (DL) transmission. The at least one OOK off-symbol is generated based on a second number of frequency resources mapped with zero values or values near zero.

[0008] In a fourth aspect, a method implemented in a terminal device is provided. The method includes receiving a wake-up signal (WUS) from a network device. The method further includes detecting the WUS and determining a plurality of on-off keying (OOK) symbols including at least one OOK on-symbol and at least one OOK off-symbol. The WUS is generated based on an output of a transform precoding of a pre-discrete Fourier transform (pre-DFT) sequence, and the pre-DFT sequence includes a plurality of pre-DFT subsequences. The pre-DFT sequence is generated based on an OOK subsequence, and the OOK subsequence includes the plurality of OOK symbols. The plurality of OOK symbols are associated with one OFDM symbol. Also, the length of a pre-DFT subsequence among the plurality of pre-DFT subsequences is associated with at least one of the number of subcarriers used for the WUS, the number of the plurality of OOK symbols, or the index of the pre-DFT subsequence among the plurality of pre-DFT subsequences.

[0009] In a fifth aspect, a method implemented in a terminal device is provided. The method includes receiving, from a network device, a downlink (DL) signal including a wake-up signal (WUS) and a normal downlink (DL) transmission. The LP-WUS and the normal DL transmission are generated using an orthogonal frequency division multiplexing (OFDM) operation. The method further includes receiving a WUS setting from the network device and determining a resource for the WUS indicated within the WUS setting. The method further includes determining an overlapping resource that is assigned to the normal DL transmission and overlaps with the resource for the WUS, and determining that the overlapping resource is not available for the normal DL transmission.

[0010] In a sixth aspect, a method implemented in a terminal device is provided. The method includes receiving, from a network device, a downlink (DL) signal including a wake-up signal (WUS) and a normal downlink (DL) transmission. The WUS includes a plurality of on-off keying (OOK) symbols including at least one OOK on-symbol and at least one OOK off-symbol. The at least one OOK on-symbol is generated based on data of the normal DL transmission. The method further includes determining indexes of a plurality of physical resource blocks (PRBs) assigned for the WUS, and determining that resource elements (REs) of the plurality of PRBs of an OFDM symbol associated with the OOK on-symbol are available for the normal DL transmission. The method further includes determining that the REs of the plurality of PRBs of the OFDM symbol associated with the OOK off-symbol are not available for the normal DL transmission.

[0011] In a seventh aspect, a network device is provided. The network device includes a processor and a memory storing instructions. The memory and the instructions are configured to cause the processor to execute the methods according to the first and second aspects in the network device.

[0012] In an eighth aspect, a terminal device is provided. The terminal device includes a processor and a memory storing instructions. The memory and the instructions are configured to cause the processor to execute the methods according to the third, fourth, fifth, and sixth aspects in the terminal device.

[0013] In a ninth aspect, a computer-readable medium storing instructions is provided. When the instructions are executed on at least one processor of a device, the instructions cause the device to execute the methods according to the first, second, third, fourth, fifth, and sixth aspects.

[0014] It should be understood that the summary section of the invention is not intended to identify important or essential features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure should be readily understandable from the following description.

Brief Description of the Drawings

[0015] Some embodiments of the present disclosure will be described in more detail in the accompanying drawings, so as to further clarify the above-mentioned and other objects, features, and advantages of the present disclosure.

[0016]

Figure 1

[0017]

Figure 2

[0018]

Figure 3

[0019]

Figure 4

[0020]

Figure 5A

[0021]

Figure 5B

[0022]

Figure 6

[0023]

Figure 7A

[0024]

Figure 7B

[0025]

Figure 7C

[0026]

Figure 8A

[0027]

Figure 8B

[0028]

Figure 9A

[0029]

Figure 9B

[0030]

Figure 10

[0031]

Figure 11

[0032]

Figure 12

[0033]

Figure 13

[0034]

Figure 14A

Figure 14B

[0035]

Figure 15

[0036]

Figure 16

[0037]

Figure 17

[0038]

Figure 18

[0039]

Figure 19

[0040]

Figure 20

[0041] In the figure, the same or similar reference numerals represent the same or similar elements.

DETAILED DESCRIPTION OF THE INVENTION

[0042] Here, the principles of the present disclosure will be described with reference to some exemplary embodiments. It should be understood that these embodiments are described for illustrative purposes only and are intended to assist those skilled in the art in understanding and implementing the present disclosure, without suggesting any limitation on the scope of the present disclosure. The disclosure described herein can be implemented in various ways different from the methods described below.

[0043] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0044] As used herein, the term "network device" refers to a device capable of providing or hosting a cell or coverage with which a terminal device can communicate. Examples of network devices include, but are not limited to, Node B (NodeB or NB), Evolved NodeB (eNodeB or eNB), Next Generation NodeB (gNB), Transmission Reception Point (TRP), Remote Radio Unit (RRU), Radio Head (RH), Remote Radio Head (RRH), IAB node, femto node, pico node and other low-power nodes, Reconfigurable Intelligent Surface (RIS), etc.

[0045] As used herein, the term "terminal device" refers to any device having a wireless or wired communication function. Examples of terminal devices include user equipment (UE), personal computers, desktops, mobile phones, cellular phones, smartphones, personal digital assistants (PDAs), portable computers, tablets, wearable devices, Internet of Things (IoT) devices, Ultra-reliable and Low Latency Communications (URLLC) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices, vehicle-mounted devices for vehicle-to-everything (V2X) communication (where X means pedestrian, vehicle, or infrastructure / network), devices of spacecraft or aircraft in non-terrestrial networks (NTN) including High Altitude Platforms (HAP) and satellites that include Unmanned Aircraft Systems (UAS), Extended Reality (XR) devices including different types of reality such as Augmented Reality (AR), Mixed Reality (MR), Virtual Reality (VR), unmanned aerial vehicles (UAVs), which are aircraft generally known as drones and do not require a human pilot, devices on high speed trains (HSTs), imaging devices such as digital cameras, sensors, gaming devices, music storage / playback devices, or Internet devices that enable wireless / wired Internet access and browsing, but are not limited thereto.The "terminal device" can further have a multicast / broadcast function, and supports public safety, mission critical, V2X applications, transparent IPv4 / IPv6 multicast delivery, IPTV, smart TV, wireless services, wireless software delivery, group communication, and IoT applications. Also, one or more subscriber identity modules (SIMs), known as multi-SIM, may be incorporated. The term "terminal device" can be used interchangeably with UE, mobile station, subscriber equipment, mobile terminal, user terminal, or wireless device.

[0046] The terminal device or network device may have the ability of artificial intelligence (AI) or machine learning. Generally, it includes models that can learn from a large number of data collected for specific functions and be used to predict some information.

[0047] The terminal device or network device may operate on several frequency ranges, such as FR1 (410 MHz to 7125 MHz), FR2 (24.25 GHz to 71 GHz), frequency bands greater than 100 GHz, and terahertz (THz). Furthermore, it can function in licensed / unlicensed / shared spectrum. In the scenario of multi-radio dual connectivity (MR-DC) application, the terminal device may have multiple connections with the network device. The terminal device or network device can function in full-duplex, flexible-duplex, and cross-division duplex modes.

[0048] Embodiments of the present disclosure may be implemented in test equipment such as, for example, signal generators, signal analyzers, spectrum analyzers, network analyzers, test terminal devices, test network devices, channel emulators, etc.

[0049] As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. The term "comprising" and variations thereof are to be construed as an open-ended term meaning "including, but not limited to". The term "based on" is to be construed as "based at least in part on". The terms "some embodiments" and "embodiments" are to be understood as "at least some embodiments". The term "another embodiment" is to be understood as "at least one other embodiment". The terms "first", "second", etc. may refer to different or the same object. Other explicit and implicit definitions may be included hereinafter.

[0050] In some instances, values, procedures, or devices are referred to as "optimal", "lowest", "highest", "minimum", "maximum", etc. Such descriptions are intended to indicate that a selection is possible from among a plurality of functional alternatives being used, and it will be understood that such a selection need not be better, smaller, higher, or more preferable than other selections.

[0051] As described above, research on low-power wake-up signals (WUS) is needed. OOK modulation is widely considered in this research because of its very simple receiver architecture and ultra-low power consumption. In OOK modulation, the receiver may only need to detect the envelope / energy of the time-domain signal at a relatively low sampling rate without complex baseband processing.

[0052] IEEE 802.11ba introduces a low-power wake-up mechanism into a WIFI system that employs multi-carrier OOK modulation. In 802.11ba, the OOK on-symbol and off-symbol are generated based on CP-OFDM symbols, and the time interval of CP-OFDM is 4 us.

[0053] However, the New Radio (NR) system may have different requirements for the WIFI system. For example, NR mainly focuses on the idle / inactive mode and needs to achieve a good trade-off between power saving and wake-up delay, and may not provide the same coverage as normal downlink / uplink (UL: uplink) transmission.

[0054] Also, existing NR channels / signals are based on OFDM waveforms that cannot directly coexist with OOK. Therefore, the WUS signal may be generated independently of other OFDM-based channels / signals. However, considering complexity and spectral efficiency, it is beneficial to reuse the OFDM framework to generate the WUS signal. For example, when WUS and normal downlink channels (e.g., Physical Downlink Control Channel (PDCCH), Physical Downlink Shared Channel (PDSCH)) are synchronized and use the same OFDM numerology, they are orthogonal in the frequency domain, so it is possible to avoid or reduce the guard band. Additionally, the time boundaries of WUS and other downlink symbols can be well aligned, which is beneficial for obtaining good resource utilization.

[0055] Using the same method as IEEE 802.11ba will cause some problems. For example, the CP-OFDM symbol of NR is much longer than that of WIFI (e.g., about 71 us in the case of NR 15KHz SCS), and using such a long OOK symbol may lead to low spectral efficiency. Multiple SCSs are supported by NR, and the time interval of the CP-OFDM symbol may depend on the numerology. Also, the CP lengths of OFDM symbols within a slot may not be the same. For example, the 0th and 7th symbols may have a longer CP than other symbols for 15KHz SCS.

[0056] In the present disclosure, OOK modulation is only an example, and other amplitude modulations, such as Amplitude Shift Keying (ASK), may be used. The term "OOK symbol" may also be replaced by "modulation symbol", the "OOK on symbol" may be replaced by "symbol with a higher amplitude", and the "OOK off symbol" may be replaced by "symbol with a lower amplitude or zero amplitude".

[0057] Embodiments of the present disclosure propose a method for generating a low-power wake-up signal. In this solution, a common OFDM operation is used for both WUS and other DL transmissions. WUS occupies only a part of the channel bandwidth and can improve spectral efficiency by being multiplexed with other DL transmissions in the frequency domain.

[0058] Hereinafter, with reference to FIGS. 1 to 20, the principles and embodiments of the present disclosure will be described in detail. In some embodiments, general settings (e.g., time / frequency resources) for WUS will be described. In some embodiments, how to generate OOK symbols when considering one CP-OFDM symbol as one OOK symbol will be described. Also, in some embodiments, how to generate OOK symbols when considering one CP-OFDM symbol as multiple OOK symbols will be described.

[0059] FIG. 1 shows an exemplary communication system 100 capable of implementing embodiments of the present disclosure. The system 100 includes terminal devices (e.g., UEs) 120 and 121, and a network device (e.g., a base station (BS)) 110 that serves the terminal devices 120 and 121. The serving area of the network device 110 is referred to as a cell 102. It should be understood that the number of network devices and terminal devices is given only for the purpose of explanation and no limitation is implied. The system 100 may include any suitable number of network devices and terminal devices suitable for implementing embodiments of the present disclosure.

[0060] In some embodiments, the terminal device 120 may be in the RRC idle / inactive state and monitor the WUS from the network device 110, while the terminal device 121 may be in the RRC connected / active state and receive the DL transmission from the network device 110. In some embodiments, to avoid potential resource collisions between the WUS and other DL transmissions, the terminal device 121 may be indicated with resources for the WUS.

[0061] The communication within the communication system 100 may be implemented according to any generation of communication protocol known currently or developed in the future. Examples of communication protocols include, but are not limited to, the first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocol, 5.5G, 5G-Advanced network, or sixth generation (6G) network.

[0062] FIG. 2 is a diagram showing an exemplary process 200 for generating a WUS signal according to some exemplary embodiments of the present disclosure. Some techniques will be described with reference to FIG. 2. By way of example, FIG. 2 shows an OOK subsequence including four OOK symbols "1010", where the OOK symbol may be an OOK on symbol (represented by "1") or an OOK off symbol (represented by "0"), the OOK sequence is a sequence of OOK symbols, and the OOK subsequence is a continuous part of the OOK sequence. In some embodiments, the OOK sequence is mapped to a plurality of OFDM symbols, the OOK subsequence is a part of the OOK sequence, and is mapped to an OFDM symbol of the plurality of OFDM symbols. In some embodiments, the term "map" indicates a conversion or association. For example, mapping an OOK sequence to a plurality of OFDM symbols may mean that the OOK sequence is converted to a plurality of OFDM symbols (i.e., the plurality of OFDM symbols are generated based on the OOK sequence), or that the OOK sequence is associated with the plurality of OFDM symbols.

[0063] As shown in FIG. 2, by performing a sequence mapping 210 on the OOK subsequence, a pre-Discrete Fourier Transform (pre-DFT) sequence is obtained. After the sequence mapping 210, each OOK symbol in the OOK subsequence is mapped to a pre-DFT subsequence, and the plurality of pre-DFT subsequences associated with the OOK symbols in the OOK subsequence are concatenated to form a pre-DFT sequence.

[0064] After the conversion pre-coding and inverse fast Fourier transform (IFFT) operation 220, the pre-DFT sequence is converted into a post-IFFT sequence. The post-IFFT sub-sequence is a consecutive portion of the post-IFFT sequence. The post-IFFT sub-sequence may be regarded as approximately the conversion from the corresponding pre-DFT sub-sequence. The post-IFFT sub-sequence associated with the OOK off symbol has relatively low power, and the post-IFFT sub-sequence associated with the OOK on symbol has relatively high power. In some embodiments, the IFFT operation may be replaced by an inverse discrete Fourier transform (IDFT).

[0065] Also, after the DFT (also referred to as conversion pre-coding) operation, the pre-DFT sequence is converted into a post-DFT sequence. This is an intermediate stage between the pre-DFT sequence and the post-IFFT sequence and is not shown in FIG. 2.

[0066] And the WUS signal includes at least one post-IFFT sequence and may optionally include other signals (such as CP, GI, padding data, or signals generated based on the padding data, etc.).

[0067] In summary, the post-IFFT sequence, the pre-DFT sequence, and the OOK sub-sequence are related to each other, the post-IFFT sub-sequence, the pre-DFT sub-sequence, and the OOK symbol are related to each other, the post-IFFT sub-sequence may be regarded as an oversampled version of the associated pre-DFT sub-sequence, and the post-IFFT sequence may be regarded as an oversampled version of the associated pre-DFT sequence.

[0068] In the present disclosure, unless otherwise specified, the term "OFDM symbol" refers to a CP-OFDM symbol or any variant of the OFDM symbol, such as GI-OFDM, zero CP OFDM, unique word OFDM, etc. And the term "OFDM without CP" refers to the output of the IFFT, and no CP or guard interval has been inserted yet.

[0069] FIG. 3 is an exemplary signaling diagram showing an exemplary process 300 of WUS according to some embodiments of the present disclosure. For the sake of explanation, process 300 will be described with reference to FIG. 1. Process 300 may involve a network (NW) device 110 as shown in FIG. 1, and terminal devices 120 and 121 (i.e., UEs 120 and 121). Although process 300 has been described in the communication system 100 of FIG. 1, this process may be similarly applied to other communication scenarios.

[0070] As shown in FIG. 3, the NW 110 generates (310) at least one OOK on symbol and generates (320) at least one OOK off symbol. In some embodiments, the OOK on symbol or the OOK off symbol is generated based on OFDM symbol generation that is also used for normal DL transmission (e.g., PDCCH, PDSCH, Channel State Information-Reference Signal (CSI-RS), etc.).

[0071] In some embodiments, multiple subcarriers may be used for OOK symbol generation. For example, a first number of subcarriers mapped with non-zero values can be used to generate OOK on symbols. The non-zero value may be a complex-valued symbol dedicated to WUS, or the non-zero value may be a value also used for normal DL channels or DL signals (e.g., PDCCH, PDSCH, Demodulation Reference Signal (DMRS), CSI-RS, positioning RS, etc.). Also, a second number of subcarriers mapped with zero values or values near zero can be used to generate OOK off symbols. The values near zero have less power than the non-zero values used for OOK on symbols. The number of the first plurality of subcarriers and the number of the second plurality of subcarriers may be different.

[0072] After at least one OOK on symbol and at least one OOK off symbol are generated, NW 110 generates WUS based on the generated OOK on symbols and OOK off symbols (330).

[0073] With this OOK symbol generation mechanism, WUS can occupy only a part of the channel bandwidth and can be multiplexed with other DL transmissions in the frequency domain. Therefore, the spectral efficiency can be improved. Also, a common OFDM operation can be used for both WUS and other DL transmissions, and WUS may be orthogonal to normal DL transmissions, so the guard band between WUS and normal DL transmissions can be reduced. For example, for at least OOK on symbols, there may be no guard band. This is because the inter-carrier interference from normal DL transmissions to WUS increases the power level of OOK on symbols at the receiver side, which is actually useful for OOK symbol detection. Since it is generated by a common OFDM operation, there may be no interference from WUS to normal DL transmissions.

[0074] Describe the frequency domain resources for WUS. In some embodiments, WUS may occupy a plurality of subcarriers or physical resource blocks (PRBs), for example, 100 subcarriers or 200 subcarriers, or 4 PRBs, 8 PRBs, 16 PRBs, 24 PRBs, or 32 PRBs, etc.

[0075] Next, refer to FIGS. 5A and 5B. FIG. 5A shows an exemplary transmitter 500 for WUS that may be included in the network device 110. FIG. 5B shows an exemplary receiver 450 for WUS that may be included in the terminal devices 120 and 121.

[0076] On the transmitter 500 side, NW 110 generates WUS and normal DL transmissions by a common OFDM generation operation. Then, as shown in FIG. 3, NW 110 transmits the WUS to UE 120 (340). In some embodiments, NW 110 transmits a DL signal including WUS and normal DL transmission to UE 121 (350). In some embodiments, NW 110 may also transmit WUS to UE 120 within a DL signal including normal DL transmission. On the receiver 550 side, UE 120 may use a filter 551 (e.g., a band-pass filter) to suppress interference from other DL transmissions to WUS and use an OOK detector 452 to detect WUS symbols.

[0077] In some embodiments, WUS may occupy frequency resources at the bandwidth edges. In other words, the PRBs allocated for WUS may be the first M PRBs (i.e., the lower bandwidth edge) or the last M PRBs (i.e., the upper bandwidth edge) of the channel bandwidth, where M is an integer. Alternatively or additionally, a subset of the subcarriers of the M PRBs is within the guard band of the channel bandwidth. In other words, the subset of the subcarriers of the M PRBs is not available subcarriers for other DL transmissions.

[0078] The advantage of allowing WUS located in the bandwidth edge or guard band may be to at least save the potential guard band between WUS and other DL transmissions. This is because only one side guard band may be required between WUS and other DL transmissions.

[0079] In some embodiments, the UE 120 may be indicated a bandwidth setting for monitoring WUS. If the UE 120 does not receive the bandwidth setting, the UE 120 may assume that the frequency resources of WUS are M PRBs at the center / upper edge / lower edge of the default bandwidth part (BWP) (e.g., the initial BWP or a pre-configured BWP). Alternatively or additionally, the frequency resources of WUS may be M PRBs at the center / upper edge / lower edge of the channel bandwidth, where the channel bandwidth may be indicated in the system information by the NW 110.

[0080] The time domain resources for WUS are described. In some embodiments, the time interval of WUS may be equal to or less than N consecutive OFDM symbols (a guard time interval may be reserved before or after the WUS signal, and the guard time interval may also be within the N OFDM symbols), where N is an integer and N may be associated with the numerology of the OFDM symbol. For example, N may be equal to s*2^u, where u is a numerology parameter that is an integer and s is an integer.

[0081] In some embodiments, WUS may start in an OFDM symbol having an index from 0, 1, 2, 3, …, 7*2^u within a subframe and end in an OFDM symbol before the OFDM symbol having an index of 7*2^u within the subframe. In other words, the WUS signal may be within the first half of the subframe or within the first OFDM symbol of the first half + the second half of the subframe. Alternatively, the WUS signal may start in an OFDM symbol having an index from 7*2^u, (7*2^u)+1, (7*2^u)+2, …, (14*2^u)-1 within the subframe and end in an OFDM symbol before the OFDM symbol having an index of (14*2^u)-1 within the subframe. In other words, the WUS signal may be within the second half of the subframe.

[0082] This may be because symbol 0 and symbol 7*2^u have a longer CP than other OFDM symbols within the subframe. If the WUS signal straddles symbol 0 or symbol 7*2^u, the time interval of the OOK symbol may not be unique, which may degrade the performance of the receiver.

[0083] Referring to FIG. 6, FIG. 6 is an exemplary diagram 600 of OFDM symbols within a subframe for 15KHz SCS (i.e., u = 0) according to some embodiments of the present disclosure.

[0084] In some embodiments, for 15KHz SCS, the WUS signal may include 7 OOK symbols, the time interval of each OOK symbol may be equal to the time interval of the OFDM symbol, and the 7 OOK symbols may be aligned with OFDM symbols 7 to OFDM symbol 13, respectively.

[0085] As shown in FIG. 6, symbol 7 is longer than other symbols. However, this does not affect the WUS detector because the WUS detector can determine the time interval of the first OOK symbol based on the boundaries of the first and second OOK symbols.

[0086] In some embodiments, when the numerology is 30KHz SCS, to align with the case of 15KHz, the WUS signal may still include 7 OOK symbols, and the time interval of each OOK symbol may be equal to the time interval of two OFDM symbols. As an example, the first OOK symbol may be aligned with OFDM symbol 14 and OFDM symbol 15, the second OOK symbol may be aligned with OFDM symbol 16 and OFDM symbol 17, and so on. As shown in FIG. 6, T1 = T2 + 16*Ts, where Ts is the reference sampling time interval.

[0087] Alternatively, for 15KHz SCS, the WUS signal may include N OOK symbols, N is less than 7, the time interval of each OOK symbol may be equal to an OFDM symbol, and the N OOK symbols may be aligned with N consecutive OFDM symbols among the last 7 OFDM symbols of the subframe.

[0088] Next, referring to FIG. 3 again. For a UE (e.g., UE 120) in the RRC idle / inactive state, the NW 110 may send the WUS configuration to the UE 120 within the system information (360).

[0089] In some embodiments, the WUS configuration may include a frequency domain resource configuration. The frequency domain resource configuration may indicate a plurality of PRBs or subcarriers occupied by the WUS signal. For example, the frequency domain resource configuration may indicate the index of the first PRB / subcarrier of the WUS and the number of PRBs / subcarriers for the WUS. If the number of PRBs / subcarriers is not indicated, a predefined / default value may be used by the UE 120. Alternatively or additionally, the frequency domain resource configuration may indicate one of the candidate resource configurations including that the WUS occupies the first M PRBs of the BWP or channel bandwidth, that the WUS occupies the last M PRBs of the BWP or channel bandwidth, that the WUS occupies the middle M PRBs of the BWP or channel bandwidth, or that the BWP or channel bandwidth is a default or preconfigured BWP or channel bandwidth.

[0090] In some embodiments, the WUS configuration may include a sequence configuration. The sequence configuration may indicate one of the sequence length (i.e., the number of OOK symbols in the sequence), the time interval between OOK symbols, or the sequence ID indicating an OOK sequence from a plurality of predefined OOK sequences.

[0091] In some embodiments, the WUS configuration may further include a time domain resource configuration. The time domain resource configuration may indicate one of the periodicity of the WUS, the duty cycle of the WUS, or the number of OOK symbols mapped to an OFDM symbol.

[0092] In some embodiments, for a UE (e.g., UE 121) in the RRC connected state, it may not be necessary to monitor the WUS. However, in order to avoid potential resource collisions between the WUS and other DL transmissions, resources for the WUS may still be indicated. Thus, the NW 110 may transmit the WUS configuration to the UE 121 via an RRC information element (360). The above information for idle / inactive UEs can be reused for connected UEs. Also, the time domain resource configuration may also indicate N consecutive OFDM symbols within a slot or subframe that may be used for the WUS.

[0093] In some embodiments, an OOK on symbol or an OOK off symbol may be mapped to a single OFDM symbol. Specifically, a part of the subcarriers of the OFDM symbol may be used to generate an OOK symbol, and other subcarriers may be used for other DL transmissions. With these approaches, it is very easy to generate an OOK symbol using existing OFDM signal generation. Furthermore, symbol / slot / subframe alignment between the WUS signal and other DL transmissions can be easily achieved.

[0094] Next, referring to FIG. 3 again. The UE 120 detects the WUS (370), for example, using a detector 552, and determines a plurality of OOK symbols including at least one OOK on symbol and at least one OOK off symbol.

[0095] In some embodiments, the UE 121 determines resources for the WUS (380). For example, the UE 121 may determine the resources for the WUS indicated in the WUS configuration. The time and frequency resources for the WUS may be indicated to the UE 121. If the resources of other DL transmissions overlap with the resources allocated to the WUS, the UE 121 may determine that the overlapping resources are not available for other DL transmissions.

[0096] As an alternative or in addition, if the OOK on-symbol is generated based on other DL transmission data, the UE 121 may determine the indexes of a plurality of PRBs assigned to the WUS. For a specific slot to which the WUS is mapped, the UE 121 may determine the sequence of the WUS (i.e., the OOK sequence) within this slot. The UE 121 may determine that the resource elements (REs) of M PRBs of the OFDM symbol associated with the OOK on-symbol are available for other DL transmissions, and may determine that the REs of M PRBs within the OFDM symbol associated with the OOK off-symbol are not available for other DL transmissions.

[0097] In some embodiments, the OOK sequence may be indicated by a downlink control information (DCI) format (e.g., DCI format 1-0, 1-1, or 1-2) that schedules the PDSCH for the UE 121. As an alternative or in addition, the UE 121 may determine that the OOK sequence is based on a preemption indication (e.g., by DCI format 2-1). Here, an S-bit preemption indication may be used, and each bit of the S-bit may represent a symbol group, and the symbol group may include at least one continuous OFDM symbol. The bit value "0" / "1" may indicate that the corresponding symbol group is associated with the OOK on-symbol (i.e., the corresponding symbol group and M PRBs are available for other DL transmissions), and the bit value "1" / "0" may indicate that the corresponding symbol group is associated with the OOK off-symbol (i.e., the corresponding symbol group and M PRBs are not available for other DL transmissions).

[0098] FIG. 7A is an exemplary diagram 700 of OOK on-symbol generation according to some embodiments of the present disclosure. In FIG. 7A, the NW 110 may generate an OOK on-symbol based on other DL transmissions.

[0099] In this case, the M PRBs allocated for WUS may actually be mapped with data of other DL transmissions, such as PDSCH, PDCCH, CSI-RS, DMRS, etc., and these DL transmissions may be transmitted to, for example, UE 121. The feasibility of this method may lie in that the OOK detector only detects the envelope or energy of the OOK symbol, which may not be affected by the value of the data mapped to the M PRBs.

[0100] FIG. 7B is an exemplary diagram 730 of OOK on-symbol generation according to some embodiments of the present disclosure. In FIG. 7B, NW 110 may generate an OOK on-symbol based on a dedicated sequence for WUS.

[0101] In this case, to generate the OOK on-symbol, a sequence, such as {S0, S1, S2, …, Sn-1}, may be mapped to the M PRBs. The elements of the sequence may be complex-valued symbols, such as symbols of binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), 16-quadrature amplitude modulation (QAM), or 64QAM, or the sequence may be a Zadoff-Chu (ZC) sequence or a computer-generated sequence.

[0102] FIG. 7C is an exemplary diagram 760 of OOK on-symbol generation according to some embodiments of the present disclosure. In FIG. 7C, NW 110 may generate an OOK on-symbol based on a dedicated sequence by conversion precoding 761 for WUS.

[0103] In this case, first, for a sequence, such as {S0, S1, S2, …, Sn-1}, conversion precoding 761 (e.g., DFT processing) may be performed, and the output of the conversion precoding may be mapped to M PRBs to generate OOK on-symbols.

[0104] In the case of the OOK on-symbol generation method of FIGS. 7A to 7C, a guard band may not be required between the WUS and other DL transmissions. In the case of OOK on-symbols, any signal component that increases the power is beneficial for detection. Therefore, on the receiver side, power leakage from other DL transmissions to the WUS does not adversely affect the envelope or energy detector. Conversely, the leakage may increase the detection power of the WUS on-symbol. On the other hand, for the UE that receives the other DL transmission, since the WUS and the other DL transmission are generated by a common OFDM operation, there may be no interference from the WUS to the other DL transmission on the receiver side.

[0105] As described above, to generate OOK off-symbols, zero values or values near zero (i.e., values having less power than the dedicated sequence for other DL transmissions or OOK on-symbols) are mapped to the M PRBs allocated for the WUS. Different from OOK on-symbols, power leakage from other DL transmissions may adversely affect the detection of OOK off-symbols on the receiver side.

[0106] FIG. 8A is an exemplary diagram 800 of OOK off-symbol generation according to some embodiments of the present disclosure. In FIG. 8A, there is no guard band reserved between the WUS and other DL transmissions. In this case, how to handle the interference from other DL transmissions to the WUS, for example, using a narrower bandpass filter, using an interference suppression algorithm, etc., may be implemented on the receiver side.

[0107] Figure 8B is an exemplary diagram 850 of OOK off-symbol generation according to some embodiments of the present disclosure. In Figure 8B, a guard band is reserved between the WUS and other DL transmissions. In some embodiments, the guard band may be filled with zero values or values near zero. Alternatively or additionally, the guard band may be filled with non-zero values, which may be based on the data of other DL transmissions. For example, the guard band may be filled with data for frequency domain spectrum shaping for other DL transmissions.

[0108] In some embodiments, the OOK on-symbol and off-symbol may be generated based on the DFT-s-OFDM waveform and may be orthogonal to other DL transmissions. In some embodiments, a single OFDM symbol can be mapped to multiple OOK symbols. In some embodiments, the CP can be treated as the useful part of the OOK symbol. Alternatively, the CP can be treated as the useless part of the OOK symbol.

[0109] With these approaches, the WUS and normal DL transmissions can be frequency division multiplexed, so the spectral efficiency can be improved. Also, since multiple OOK symbols can be mapped to a single OFDM symbol, a longer OOK sequence can be used for a specific time interval, which may be beneficial for the detection performance.

[0110] Next, refer to Figure 4. Figure 4 is an exemplary signaling diagram showing another exemplary process 400 of the WUS according to some embodiments of the present disclosure. For the sake of explanation, process 400 will be described with reference to Figure 1. Process 400 may involve a network (NW) device 110 as shown in Figure 1 and a terminal device 120 (i.e., UE 120). Although process 400 has been described in the communication system 100 of Figure 1, this process may be similarly applied to other communication scenarios.

[0111] As shown in FIG. 4, NW 110 forms an OOK sub-sequence with a plurality of OOK symbols including at least one OOK on-symbol and at least one OOK off-symbol (410). The plurality of OOK symbols may be associated with one OFDM symbol. NW 110 maps the OOK sub-sequence to a plurality of pre-DFT sub-sequences respectively to form a pre-DFT sequence (420). Then, NW 110 performs transform precoding on the pre-DFT sequence (430). Also, NW 110 maps the output of the transform precoding to the frequency resources assigned to the WUS to generate the WUS (440). The length of the pre-DFT sub-sequence among the plurality of pre-DFT sub-sequences may be associated with at least one of the number of sub-carriers used for the WUS, the number of the plurality of OOK symbols, or the index of the pre-DFT sub-sequence among the plurality of pre-DFT sub-sequences.

[0112] Also, NW 110 transmits the WUS to UE 120 (450). UE 120 detects the WUS and determines a plurality of OOK symbols including at least one OOK on-symbol and at least one OOK off-symbol (460). In some embodiments, the WUS is generated based on the output of the transform precoding of the pre-DFT sequence, and the pre-DFT sequence includes a plurality of pre-DFT sub-sequences. The pre-DFT sequence is generated based on the OOK sub-sequence, and the OOK sub-sequence includes the plurality of OOK symbols. The plurality of OOK symbols are associated with one OFDM symbol. Also, the length of the pre-DFT sub-sequence among the plurality of pre-DFT sub-sequences is associated with at least one of the number of sub-carriers used for the WUS, the number of the plurality of OOK symbols, or the index of the pre-DFT sub-sequence among the plurality of pre-DFT sub-sequences.

[0113] Regarding the details of WUS generation and detection shown in FIG. 4, reference is made to FIGS. 9A to 14B for description. FIGS. 9A and 9B show OOK symbol generation based on DFT-s-OFDM waveforms according to some embodiments of the present disclosure. FIG. 9A is shown as 900 as a whole, and FIG. 9B is shown as 950 as a whole. In some embodiments, k OOK symbols can be mapped to one OFDM symbol, and the k OOK symbols can form an OOK subsequence, i.e., {C0, C1, C2, …, Ck-1}, where k is an integer greater than 1, and the OOK symbol Ci (0 ≦ i < k) is equal to 0 or 1.

[0114] As shown in FIGS. 9A and 9B, the OOK subsequence may be mapped to a pre-DFT sequence, i.e., {S0, S1, S2, …, Sn-1} (901), and the pre-DFT sequence may include k pre-DFT subsequences. In other words, each OOK symbol in the OOK subsequence may be mapped to a pre-DFT subsequence (901).

[0115] Then, conversion precoding 902 (i.e., DFT conversion) may be performed on the pre-DFT sequence, and the output of the conversion precoding may be mapped to the M PRBs assigned to the WUS.

[0116] In some embodiments, as shown in FIG. 9A, a single IFFT operation may be performed for the other DL transmission and the WUS (903), and a CP may be inserted (904).

[0117] In some embodiments, as shown in FIG. 9B, an independent IFFT operation may be performed for the WUS (905), and a GI may be inserted before the output of the IFFT (906). The length of the GI may be the same as the length of the CP for the other DL transmission. The GI may be zero-value samples, a dedicated sequence, a copy or transformation of a specific part of the output of the IFFT, or a CP.

[0118] Next, the case where the CP is treated as the useful part of the OOK symbol will be discussed. FIG. 10 shows an exemplary diagram 1000 of an OOK sequence having a CP of an OFDM symbol treated as the useful part of the OOK symbol.

[0119] In FIG. 10, the number of subcarriers used for WUS is N wus and the length of the OFDM symbol without CP is N ofdm samples, and it is assumed that the length of the CP is N cp samples. And the ideal length of each OOK symbol should be (N ofdm +N cp ) / k, that is, 1 / k of the length of the OFDM symbol. However, since there may be only N ofdm samples after the IFFT transform, the CP may be considered in the OOK sequence mapping.

[0120] As described above, the OOK sub-sequence may be mapped to k pre-DFT sub-sequences. Specifically, each OOK symbol in the OOK sub-sequence is mapped to a pre-DFT sub-sequence. However, the lengths of the pre-DFT sub-sequences may be different. Specifically, the first pre-DFT sub-sequence may be shorter than the other sub-sequences. The lengths of the k pre-DFT sub-sequences may be determined based on N ofdm , N cp , k and N wus and the difference in length between the first pre-DFT sub-sequence and any of the other sub-sequences may be associated with the length of the CP.

[0121] For example, the length of the pre-DFT sub-sequence other than the first pre-DFT sub-sequence (denoted by N1) is the above ideal length ((N ofdm +N cp ) / k) and the scaling factor (N wus / N ofdm) may be determined based on this. N1 is, N1=(N ofdm +N cp ) / k*N wus / N ofdm (1), or N1=floor[(N ofdm +Ncp) / k*N wus / N ofdm (2), or N1=ceil[(N ofdm +N cp ) / k*N wus / N ofdm (3), may be defined as.

[0122] Here, floor[] is a function that gives the largest integer less than or equal to the input as the output, and ceil[] is a function that gives the smallest integer greater than or equal to the input as the output.

[0123] Also, the length of the first pre-DFT subsequence (indicated by N0) may be determined based on the ideal length ((N ofdm +N cp ) / k), the CP length, and the scaling factor ((N ofdm +N cp ) / k). Alternatively, N0 may be directly based on N wus and N1. N0 is, N0=N wus -(k - 1)*N1(4), or N0=[(N ofdm +N cp ) / k - N cp *N wus / N ofdm (5), or N0=floor{[(N ofdm +N cp ) / k - N cp *N wus / N ofdm} (6), or N0=ceil{[(N ofdm +N cp ) / k - N cp *N wus / N ofdm}(7), may be defined as.

[0124] After the IFFT and before the CP insertion, an OFDM symbol without CP may be generated and may include k post-IFFT subsequences, and each of the k post-IFFT subsequences may be associated with an OOK symbol.

[0125] FIG. 11 shows an exemplary diagram 1100 of the OOK sequence of FIG. 10 with GI inserted according to some embodiments of the present disclosure. In FIG. 11, the length of the first post-IFFT subsequence may be shorter than that of the other subsequences, and the first post-IFFT subsequence is represented as {P0, P1, …, Pj}, where j = (N ofdm +N cp ) / k - N cp - 1. And the GI may be inserted before the output of the IFFT, and the GI sequence is {Q0, Q1, …, Qi}, and it is assumed that i = N cp - 1.

[0126] In some embodiments, the GI sequence may be generated based on the first post-IFFT subsequence. For example, when i ≤ j, {Q0, Q1, …, Qi} may be equal to the first (i + 1) samples or the last (i + 1) samples of {P0, P1, …, Pj}. Alternatively, when i > j, {P0, P1, …, Pj} may be repeated and truncated to (i + 1) samples to generate {Q0, Q1, …, Qi}.

[0127] In some embodiments, the GI sequence may be generated based on the first post-IFFT subsequence in reverse order. For example, when i ≤ j, {Q0’, Q1’, …, Qi’} may be equal to the first (i + 1) samples or the last (i + 1) samples of {P0, P1, …, Pj}, and {Q0, Q1, …, Qi} = {Qi’, Qi-1’, …, Q0’}. Alternatively, when i > j, to generate {Q0’, Q1’, …, Qi’}, {P0, P1, …, Pj} may be repeated and truncated to (i + 1) samples, and {Q0, Q1, …, Qi} = {Qi’, Qi-1’, …, Q0’}.

[0128] Alternatively, the above GI sequence generation can be performed only when the first OOK symbol among the k OOK symbols is an OOK on-symbol. When the first OOK symbol of the k OOK symbols is an OOK off-symbol, all elements of the GI sequence may be zero values or values near zero.

[0129] Alternatively or additionally, when the first OOK symbol and the last OOK symbol are the same, i.e., both are OOK off-symbols or OOK on-symbols, {Q0, Q1, …, Qi} may be the last (i + 1) samples of the last post-IFFT subsequence. In other words, GI may be inserted as normal CP processing. In some embodiments, the OOK sequence may be designed such that the values of the first and last OOK symbols in the OOK subsequence are the same.

[0130] Without suggesting any limitation, for illustration purposes, an example is shown below. Assume that the SCS is 15 KHz, 24 PRBs (i.e., 288 subcarriers) are used for the WUS, and 4 OOK symbols are mapped to an OFDM symbol. Assuming that the IFFT size is 2048 and the CP length is 144 samples, for the last 3 symbols of the OOK sub-sequence, each of these symbols may be mapped to a pre-DFT sequence having a length of floor{[(2048 + 144) / 4]*288 / 2048} = 77.

[0131] The first symbol of the OOK sub-sequence may be mapped to a pre-DFT sequence having a length of 288 - 3*77 = 57.

[0132] In this case, the OOK symbol may be generated by the following steps.

[0133] In step 1, based on the 4 OOK symbols having the above length, 4 pre-DFT sub-sequences are generated and concatenated to form a pre-DFT sequence having a length of 288 points.

[0134] In step 2, 288-point DFT processing may be performed on the 288-point pre-DFT sequence, and a 288-point post-DFT sequence may be generated.

[0135] In step 3, the 288 elements of the post-DFT sequence are each mapped to the 288 subcarriers of 24 PRBs, and by performing a 2048-point IFFT, an OFDM symbol without CP having 2048 samples may be generated.

[0136] In step 4, a 144-point GI may be generated and inserted before the 2048 samples.

[0137] Based on this method, the time interval of the OFDM symbol (i.e., 2048 + 144 = 2192 samples) may be roughly divided into four parts on average (i.e., ~2192 / 4 = 548 samples), and each of the four parts may represent an OOK symbol.

[0138] Next, the case where the CP is treated as the useless part of the OOK symbol will be discussed. In this case, assume that the WUS receiver (e.g., receiver 550) can identify and remove the CP / GI, and the OOK symbol is mapped only to the useful part of the OFDM symbol, that is, the CP / GI is not the useful part of the OOK symbol.

[0139] FIG. 12 shows an exemplary diagram 1200 of an OOK sequence having a CP treated as the useless part of the OOK symbol according to some embodiments of the present disclosure. Still, the number of subcarriers used for the WUS is N wus and the length of the OFDM symbol without CP is N ofdm samples, and assume that the length of the CP is N cp .

[0140] As shown in FIG. 12, the lengths of the k pre-DFT sub-sequences are the same, and the length (represented by N2) is N2 = N wus / k (8) and may be defined as such.

[0141] When only one OFDM symbol is used to generate the WUS signal, the WUS receiver only needs to detect the k OOK symbols, and the CP will not cause confusion during detection. However, when multiple OFDM symbols are used to generate the WUS signal, there is a CP between the OOK symbols, and the WUS receiver must identify which part of its received signal is the CP.

[0142] FIG. 13 is an exemplary diagram 1300 of an OOK sequence where the time interval of the CP is different from the time interval of the OOK sequence. In some embodiments, a plurality of OOK symbols may be mapped to one OFDM symbol, and the CP may be inserted normally. Therefore, the time interval of the CP may be regarded as the useless part for the WUS signal, and the receiver should be able to remove this part. However, as shown in FIG. 13, the time interval of the CP may be different from the time interval of the post-IFFT subsequence of the OOK symbol. This may cause some difficulties for the receiver.

[0143] In some embodiments, by increasing the complexity of the receiver, it is possible to cope with this problem of non-uniform symbol time intervals. For example, the receiver may have a relatively high oversampling rate, relatively fine time synchronization, and relatively complex baseband processing.

[0144] In addition, the OOK sequence may be designed to facilitate CP detection. For example, assuming that two OOK subsequences are mapped to two OFDM symbols respectively, the second OOK subsequence may be a repetition of the first OOK subsequence. Alternatively, these two OOK subsequences may be generated based on the same sequence, but may be multiplied by two sets of coefficients respectively (for example, the two sets of coefficients are two orthogonal cover codes (OCCs)). By these two methods, since the two OOK subsequences are correlated, a self-correlation detector with relatively low complexity may be applied to detect the CP part.

[0145] In some embodiments, the "padding data" may be inserted at the beginning or end of the pre-DFT sequence. The purpose is to make the gap between two non-consecutive OOK symbols equal to an integer multiple of the OOK symbol length. FIGS. 14A and 14B show exemplary diagrams of an OOK sequence with padding data inserted between non-consecutive OOK symbols. FIG. 14A is shown as 1400 as a whole, and FIG. 14B is shown as 1450 as a whole.

[0146] For example, in FIG. 14A, OOK3 and OOK4 are non-consecutive, and the gap between them is equal to the time interval of an OOK symbol. OOK6 and OOK7 are also non-consecutive, and the gap between them is equal to the time interval of two OOK symbols. In FIG. 14B, OOK2 and OOK3 are non-consecutive, and the gap between them is equal to the time interval of an OOK symbol. OOK5 and OOK6 are also non-consecutive, and the gap between them is also equal to the time interval of an OOK symbol.

[0147] To make the gap between two non-consecutive OOK symbols equal to an integer multiple of the OOK symbol length, a padding data sequence including one or more padding data may be inserted at the beginning or end of the pre-DFT sequence. The padding data may be zero, or a pre-defined sequence, or a copy or transformation of a part of the pre-DFT sequence.

[0148] In some embodiments, the length of the padding data sequence may be determined based on the CP length and index of the OFDM symbol among the OFDM symbols for the WUS signal. Without suggesting any limitation, for illustration, if L OFDM symbols are used for the WUS signal and the length of the post-IFFT subsequence for the OOK symbol is N ook Assuming that is the case, for the l-th (0 < l < L) OFDM symbol, the length of the padding data sequence (denoted by N4) at the beginning of the pre-DFT sequence is N’4={ceil[l*(Nofdm +N cp ) / N ook *N ook -l*(N ofdm +N cp )}*(N wus / N ofdm ) and N4 = N'4(9), or N4 = floor(N'4) (10), or N4 = ceil(N'4) (11) may also be true.

[0149] The length of the padding data sequence at the end of the pre-DFT sequence (indicated by N5) is N'5 = {[(l + 1)*N ofdm + l*N cp -floor{[(l + 1)*N ofdm + l*N cp / N ook}*N ook}*(N wus / N ofdm ) and N5 = N'5(12), or N5 = floor(N'5) (13), or N5 = ceil(N'5) (14) may also be true.

[0150] Alternatively or additionally, an offset value may be set. In this case, the length of the padding data may also be determined based on the offset value. For example, the length value determined based on the above method may be plus or minus the offset value, or the offset value may be used in the above formula.

[0151] FIG. 15 is a flowchart of an exemplary method 1500 according to some embodiments of the present disclosure. Method 1500 can be implemented in a network device, such as network device 110 as shown in FIG. 1.

[0152] In block 1510, the network device 110 generates at least one OOK on-symbol using a first number of frequency resources mapped with non-zero values. The non-zero values are used for normal DL transmission.

[0153] In block 1520, the network device 110 generates at least one OOK off-symbol using a second number of frequency resources mapped with zero values or values near zero.

[0154] In some embodiments, the first number of frequency resources and the second number of frequency resources may include at least one of a first plurality of physical resource blocks (PRBs) or sub-carriers of the channel bandwidth, the last plurality of PRBs or sub-carriers of the channel bandwidth, or the guard band of the channel bandwidth.

[0155] In block 1530, the network device 110 generates a WUS based on the at least one OOK on-symbol and the at least one OOK off-symbol. In some embodiments, the network device 110 may generate a WUS using OFDM operations. The OFDM operations can be used to generate normal DL transmission.

[0156] In some embodiments, the time interval of the WUS may be associated with the numerology for OFDM symbols. In some embodiments, the WUS may be mapped to an OFDM symbol within a sub-frame, and the WUS may be within one of the first half of the sub-frame, the first OFDM symbol of the first half + the second half of the sub-frame, or the second half of the sub-frame.

[0157] In some embodiments, the network device may transmit the WUS configuration to a terminal device in the RRC idle or inactive state within the system information. Alternatively or additionally, the network device 110 may transmit the WUS configuration to a terminal device in the RRC connected state via RRC signaling.

[0158] In some embodiments, the WUS configuration may include a frequency domain resource configuration. The frequency domain resource configuration may indicate a plurality of frequency resources occupied by the WUS. Alternatively or additionally, the WUS configuration may include a time domain resource configuration. The time domain resource configuration may indicate at least one of the periodicity of the WUS, the duty cycle of the WUS, and the number of OOK symbols mapped to OFDM symbols. The OOK symbols may include the at least one OOK on symbol and the at least one OOK off symbol, and a plurality of consecutive OFDM symbols within a slot or subframe used for the WUS. Alternatively or additionally, the WUS configuration may include a sequence configuration. The sequence configuration may indicate at least one of the sequence length of the OOK symbols, the time interval of the OOK symbols, and the sequence ID indicating the OOK sequence from a plurality of predefined OOK sequences.

[0159] In some embodiments, the network device 110 may reserve a guard band between the WUS and the normal DL transmission. The guard band may be filled with one of the zero value or a value near zero, or a value based on the data of the normal DL transmission.

[0160] In some embodiments, the value near zero may have a power smaller than the non-zero value.

[0161] In block 1540, the network device 110 transmits the WUS to the terminal device.

[0162] FIG. 16 is a flowchart of an exemplary method 1600 according to some embodiments of the present disclosure. The method 1600 can be implemented in a network device, for example, the network device 110 as shown in FIG. 1.

[0163] In block 1610, the network device 110 forms an OOK subsequence with a plurality of OOK symbols including at least one OOK on symbol and at least one OOK off symbol. The plurality of OOK symbols are associated with one OFDM symbol.

[0164] In block 1620, the network device 110 maps the OOK subsequence to a plurality of pre-DFT subsequences respectively to form a pre-DFT sequence. The length of the pre-DFT subsequence among the plurality of pre-DFT subsequences is associated with at least one of the number of subcarriers used for WUS, the number of the plurality of OOK symbols, or the index of the pre-DFT subsequence among the plurality of pre-DFT subsequences.

[0165] In some embodiments, the network device 110 inserts padding data at the start portion or the end portion of the pre-DFT sequence. The padding data may be at least one of zero, a predefined sequence, or a copy of a part of the pre-DFT subsequence. The length of the padding data may be determined based on at least one of the CP length and index of the OFDM symbol among the plurality of OFDM symbols, or an offset value.

[0166] In block 1630, the network device 110 performs conversion precoding on the pre-DFT sequence.

[0167] In block 1640, the network device 110 maps the output of the transform precoding to the frequency resources assigned to the WUS and generates the WUS.

[0168] In some embodiments, the network device 110 may perform an IFFT operation on the output of the transform precoding and the data for normal DL transmission, and insert a CP into the output of the IFFT operation. Alternatively, the network device 110 may perform an IFFT operation on the output of the transform precoding and insert a GI before the output of the IFFT operation. The length of the GI may be the same as the length of the CP. Also, the GI may be one of zero-value samples, a dedicated sequence, a copy or transformation of a part of the output of an independent IFFT operation, or a CP.

[0169] In some embodiments, the length of the pre-DFT sub-sequence among the plurality of pre-DFT sub-sequences may further be associated with at least one of the length of an OFDM symbol without CP and the length of the CP. Also, the difference in length between the first pre-DFT sub-sequence and any of the other pre-DFT sub-sequences may be associated with the length of the CP.

[0170] In some embodiments, the length of the first pre-DFT sub-sequence may be associated with at least one of the length of the pre-DFT sub-sequences other than the first pre-DFT sub-sequence and the number of sub-carriers used for the WUS.

[0171] In some embodiments, the output of the independent IFFT operation may include a plurality of post-IFFT subsequences. According to the determination that the first OOK symbol among the plurality of OOK symbols is an OOK on symbol, the network device 110 may generate a GI sequence based on the first post-IFFT subsequence among the plurality of post-IFFT subsequences, or the first post-IFFT subsequence in reverse order. Alternatively or additionally, according to the determination that the first OOK symbol among the plurality of OOK symbols is an OOK off symbol, the network device 110 may generate a GI sequence with a zero value or a value near zero. Alternatively or additionally, according to the determination that the first OOK symbol and the last OOK symbol among the plurality of OOK symbols are the same, the network device 110 may generate a GI sequence with the last post-IFFT subsequence among the plurality of post-IFFT subsequences.

[0172] In some embodiments, according to the determination that a plurality of OOK subsequences are associated with a plurality of OFDM symbols, at least one of the plurality of OOK subsequences may be a repetition of the first OOK subsequence among the plurality of OOK subsequences. Alternatively or additionally, the plurality of OOK subsequences may be generated based on the same sequence and multiplied by two sets of coefficients respectively.

[0173] In block 1650, the network device 110 transmits the WUS to the terminal device.

[0174] FIG. 17 is a flowchart of an exemplary method 1700 according to some embodiments of the present disclosure. The method 1700 can be implemented in a terminal device, for example, the terminal device 120 as shown in FIG. 1.

[0175] In block 1710, the terminal device 120 receives a WUS from the network device.

[0176] In block 1720, the terminal device 120 detects the WUS and determines a plurality of OOK symbols including at least one OOK on-symbol and at least one OOK off-symbol.

[0177] In some embodiments, the at least one OOK on-symbol is generated based on a first number of frequency resources mapped with non-zero values. The non-zero values are used for normal DL transmission. The at least one OOK off-symbol is generated based on a second number of frequency resources mapped with zero values or values near zero.

[0178] In some embodiments, the WUS may be generated based on OFDM operation. The OFDM operation can be used to generate normal DL transmission.

[0179] In some embodiments, in accordance with a determination that the terminal device is in the Radio Resource Control (RRC) idle or inactive state, the terminal device may receive the WUS setting in the system information from the network device and monitor the WUS. Alternatively or additionally, in accordance with a determination that the terminal device is in the RRC connected state, the terminal device may receive the WUS setting via RRC signaling from the network device. In some embodiments, the WUS setting may include a frequency domain resource setting. The frequency domain resource setting may indicate a plurality of frequency resources occupied by the WUS. Alternatively or additionally, the WUS setting may include a time domain resource setting. The time domain resource setting may indicate at least one of the periodicity of the WUS, the duty cycle of the WUS, and the number of OOK symbols mapped to OFDM symbols. The OOK symbols may include the at least one OOK on symbol and the at least one OOK off symbol, and a plurality of consecutive OFDM symbols within a slot or subframe used for the WUS. Alternatively or additionally, the WUS setting may include a sequence setting. The sequence setting may indicate at least one of the sequence length of the OOK symbols, the time interval of the OOK symbols, and a sequence ID indicating an OOK sequence from a plurality of predefined OOK sequences.

[0180] In some embodiments, in response to not receiving the WUS setting from the network device 110, the terminal device 120 may detect the WUS based on an assumption that a plurality of frequency resources for the WUS are at least one of a plurality of central PRBs of the default BWP, a plurality of upper edge PRBs of the default BWP, a plurality of lower edge PRBs of the default BWP, a plurality of central PRBs of the channel bandwidth, a plurality of upper edge PRBs of the channel bandwidth, or a plurality of lower edge PRBs of the channel bandwidth.

[0181] In some embodiments, the terminal device 120 may determine the time interval of the first OOK symbol among the plurality of OOK symbols based at least on the boundary between the first OOK symbol and the second OOK symbol of the plurality of OOK symbols.

[0182] In some embodiments, the non-zero value may include the data of the normal DL transmission.

[0183] In some embodiments, the terminal device 120 may determine a guard band reserved between the WUS and the normal DL transmission. The guard band may be filled with one of the zero value or a value near zero, or a value based on the data of the normal DL transmission.

[0184] In some embodiments, the value near zero may have a power smaller than that of the non-zero value.

[0185] In some embodiments, the WUS is generated based on the output of the transform precoding of the pre-DFT sequence, and the pre-DFT sequence includes a plurality of pre-DFT subsequences. The pre-DFT sequence is generated based on an OOK subsequence, and the OOK subsequence includes the plurality of OOK symbols. The plurality of OOK symbols are associated with one OFDM symbol. Also, the length of the pre-DFT subsequence among the plurality of pre-DFT subsequences is associated with at least one of the number of subcarriers used for the WUS, the number of the plurality of OOK symbols, or the index of the pre-DFT subsequence among the plurality of pre-DFT subsequences.

[0186] In some embodiments, the terminal device 120 may receive the WUS and the normal downlink (DL) transmission in the DL signal.

[0187] In some embodiments, the WUS and the normal DL transmission may be generated by an IFFT operation, and the CP may be inserted into the output of the IFFT operation. Alternatively or additionally, the WUS may be generated by an independent IFFT operation, and the GI may be inserted into the output of the independent IFFT operation.

[0188] In some embodiments, the length of the pre-DFT subsequence among the plurality of pre-DFT subsequences may be associated with at least one of the length of an OFDM symbol without CP and the length of the CP. The difference in length between the first pre-DFT subsequence and any of the other pre-DFT subsequences may be associated with the length of the CP.

[0189] In some embodiments, the length of the first pre-DFT subsequence may be associated with at least one of the length of the pre-DFT subsequences other than the first pre-DFT subsequence and the number of subcarriers used for the WUS.

[0190] In some embodiments, the output of the independent IFFT operation may include a plurality of post-IFFT subsequences. According to the determination that the first OOK symbol among the plurality of OOK symbols is an OOK on symbol, the GI sequence may be generated based on the first post-IFFT subsequence among the plurality of post-IFFT subsequences, or the first post-IFFT subsequence in reverse order. Alternatively or additionally, according to the determination that the first OOK symbol among the plurality of OOK symbols is an OOK off symbol, the GI sequence may be generated with a zero value or a value near zero. Alternatively or additionally, according to the determination that the first OOK symbol and the last OOK symbol among the plurality of OOK symbols are the same, the GI sequence may be generated based on the last post-IFFT subsequence among the plurality of post-IFFT subsequences.

[0191] In some embodiments, at least one of the plurality of OOK sub-sequences may be a repetition of a first OOK sub-sequence among the plurality of OOK sub-sequences. Alternatively or additionally, the plurality of OOK sub-sequences may be generated based on the same sequence and multiplied by two sets of coefficients respectively.

[0192] In some embodiments, the WUS may be generated based on the output of the transform precoding of a pre-DFT sequence with padding data inserted at the start or end. The padding data may be at least one of zero, a predefined sequence, or a copy of a part of the pre-DFT sub-sequence. The length of the padding data sequence may be determined based on at least one of the CP length and index of the OFDM symbols among the plurality of OFDM symbols, or an offset value.

[0193] FIG. 18 is a flowchart of an exemplary method 1800 according to some embodiments of the present disclosure. The method 1800 can be implemented in a terminal device, for example, the terminal device 121 as shown in FIG. 1.

[0194] In block 1810, the terminal device 121 receives a DL signal including a WUS and a normal DL transmission from a network device. The LP-WUS and the normal DL transmission are generated using OFDM operations.

[0195] In block 1820, the terminal device 121 receives a WUS configuration from the network device.

[0196] In some embodiments, the WUS may include a plurality of OOK symbols. Also, the WUS configuration may include a frequency domain resource configuration. The frequency domain resource configuration may indicate a plurality of frequency resources occupied by the WUS. Alternatively or additionally, the WUS configuration may include a time domain resource configuration. The time domain resource configuration may indicate at least one of the periodicity of the WUS, the duty cycle of the WUS, and the number of OOK symbols mapped to OFDM symbols. The OOK symbols may include the at least one OOK on symbol and the at least one OOK off symbol, and a plurality of consecutive OFDM symbols within a slot or subframe used for the WUS. Alternatively or additionally, the WUS configuration may include a sequence configuration. The sequence configuration may indicate at least one of the sequence length of the OOK symbols, the time interval of the OOK symbols, and a sequence ID indicating an OOK sequence from a plurality of predefined OOK sequences.

[0197] In block 1830, the terminal device 121 determines resources for the WUS indicated within the WUS configuration.

[0198] In block 1840, the terminal device 121 determines overlapping resources that are allocated for normal DL transmission and overlap with the resources for the WUS.

[0199] In block 1850, the terminal device 121 determines that the overlapping resources are not available for normal DL transmission.

[0200] FIG. 19 is a flowchart of an exemplary method 1900 according to some embodiments of the present disclosure. The method 1900 can be implemented in a terminal device, for example, the terminal device 121 as shown in FIG. 1.

[0201] In block 1910, the terminal device 121 receives a DL signal including a WUS and normal DL transmission from the network device. The WUS may include a plurality of OOK symbols including at least one OOK on-symbol and at least one OOK off-symbol. The at least one OOK on-symbol is generated based on the data of the normal DL transmission.

[0202] In block 1920, the terminal device 121 determines the indexes of a plurality of PRBs assigned to the WUS.

[0203] In block 1930, the terminal device 121 determines that the REs of the plurality of PRBs of the OFDM symbol associated with the OOK on-symbol are available for the normal DL transmission.

[0204] In block 1940, the terminal device 121 determines that the REs of the plurality of PRBs of the OFDM symbol associated with the OOK off-symbol are not available for the normal DL transmission.

[0205] FIG. 20 is a schematic block diagram of an apparatus 2000 suitable for implementing some embodiments of the present disclosure. The apparatus 2000 can be considered as another exemplary embodiment of the network device 110 shown in FIG. 1, or the terminal devices 120 and 121. Therefore, the apparatus 2000 may be implemented in the network device 110, or the terminal devices 120 and 121, or as at least a part thereof.

[0206] As shown, apparatus 2000 includes a processor 2010, a memory 2020 coupled to the processor 2010, a suitable transmitter (TX) and receiver (RX) 2040 coupled to the processor 2010, and a communication interface coupled to the TX / RX 2040. The memory 2020 stores at least a portion of program 2030. The TX / RX 2040 is used for two-way communication. The TX / RX 2040 has at least one antenna to facilitate communication, although the access nodes referred to herein may actually have multiple antennas. The communication interface may represent any interface necessary for communication with other network elements, such as an X2 interface for two-way communication between gNBs or eNBs, an S1 interface for communication between a Mobility Management Entity (MME) / Serving Gateway (S-GW) and a gNB or eNB, a Un interface for communication between a gNB or eNB and a relay node (RN), or a Uu interface for communication between a gNB or eNB and a terminal device.

[0207] It is assumed that program 2030 includes program instructions that, when executed by the associated processor 2010 with reference to FIGS. 1-19 described herein, enable apparatus 2000 to operate in accordance with embodiments of the present disclosure. Embodiments herein may be implemented by computer software executable by the processor 2010 of apparatus 2000, or by hardware, or by a combination of software and hardware. The processor 2010 may be configured to implement various embodiments of the present disclosure. Further, the combination of the processor 2010 and the memory 2020 may form processing means 2050 suitable for implementing various embodiments of the present disclosure.

[0208] Memory 2020 may be of any type suitable for a local technology network and, by way of non-limiting example, may be implemented using any suitable data storage technology such as a non-transitory computer-readable storage medium, a semiconductor-based memory device, a magnetic memory device and system, an optical memory device and system, a fixed memory and a removable memory. Although only one memory 2020 is shown within device 2000, there may be several physically different memory modules within device 2000. Processor 2010 may be of any type suitable for a local technology network and, by way of non-limiting example, may include one or more of a general-purpose computer, a dedicated computer, a microprocessor, a digital signal processor (DSP) and a processor based on a multi-core processor architecture. Device 2000 may have a plurality of processors, for example, application-specific integrated circuit chips that are temporally dependent on a clock that synchronizes a main processor.

[0209] The components included in the devices and / or apparatuses of the present disclosure may be implemented in various forms including software, hardware, firmware, or any combination thereof. In one embodiment, one or more units may be implemented using software and / or firmware such as machine-executable instructions stored on a storage medium. In addition to or instead of the machine-executable instructions, some or all of the units within the devices and / or apparatuses may be implemented at least partially by one or more hardware logic components. By way of example and not limitation, exemplary types of hardware logic components that may be used include field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-a-chip systems (SOCs), complex programmable logic devices (CPLDs), and the like.

[0210] Overall, the various embodiments of the present disclosure may be implemented in hardware or dedicated circuitry, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that can be executed by a controller, a microprocessor, or other computing device. Although the various aspects of the embodiments of the present disclosure are illustrated and described using block diagrams, flowcharts, or other pictorial representations, it should be understood that the blocks, devices, systems, techniques, or methods described herein may be implemented, by way of non-limiting example, in hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or a controller or other computing device, or any combination thereof.

[0211] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions included in program modules, that are executed within an apparatus on a target physical processor or virtual processor to perform the process or method described above with reference to any one of FIGS. 1 to 19. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. In various embodiments, the functions of the program modules may be combined or divided among the program modules as needed. The machine-executable instructions of the program modules may be executed within a local or distributed apparatus. In a distributed apparatus, the program modules may be disposed in both local and remote storage media.

[0212] The program code for executing the method of the present disclosure may be described in any combination of one or more programming languages. These program codes are provided to a processor or controller of a general-purpose computer, a dedicated computer, or other programmable data processing equipment, and when executed by the processor or controller, cause the functions / operations specified in the flowchart and / or block diagram to be implemented by the program code. The program code may be executed entirely on the machine, partially on the machine, as an independent software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0213] The above program code may be embodied on a machine-readable medium, which may be any tangible medium that includes or stores a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine-readable storage medium include an electrical connection including one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0214] Note that although the operations have been described in a particular order, it should not be understood that such operations must be performed in the particular order shown or in sequence, or that all of the operations shown must be performed, to obtain a desired result. In some situations, multitasking and parallel processing may be advantageous. Similarly, although the above discussion includes some specific implementation details, these are not limitations on the scope of the present disclosure and should be construed as descriptions of features that may be specific to particular embodiments. Some features described in the context of individual embodiments may be implemented in combination in one embodiment. Conversely, various features described in the context of one embodiment may be implemented separately in multiple embodiments or in any suitable sub-combination.

[0215] Although the present disclosure has been described in terms of words specific to structural features and / or methodological acts, it is to be understood that the disclosure defined by the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

[0216] In short, embodiments of the present disclosure can provide the following solutions.

[0217] A method implemented in a network device includes generating at least one on-off keying (OOK) on-symbol using a first number of frequency resources mapped with non-zero values for normal downlink (DL) transmission, generating at least one OOK off-symbol using a second number of frequency resources mapped with zero values or values near zero, generating a wake-up signal (WUS) based on the at least one OOK on-symbol and the at least one OOK off-symbol, and transmitting the WUS to a terminal device.

[0218] In some embodiments, generating the WUS includes generating the WUS using an orthogonal frequency division multiplexing (OFDM) operation, where the OFDM operation is used to generate normal DL transmission.

[0219] In some embodiments, the first number of frequency resources and the second number of frequency resources include at least one of a first plurality of physical resource blocks (PRBs) or sub-carriers of a channel bandwidth, a last plurality of PRBs or sub-carriers of the channel bandwidth, or a guard band of the channel bandwidth.

[0220] In some embodiments, the time interval of the WUS is associated with the numerology for the OFDM symbol.

[0221] In some embodiments, the WUS is mapped to OFDM symbols within a subframe. The WUS is within one of the first half subframe, the first OFDM symbol of the first half subframe + the second half subframe, or the second half subframe.

[0222] In some embodiments, the method further includes one of transmitting the WUS configuration in system information to a terminal device in a Radio Resource Control (RRC) idle or inactive state, or transmitting the WUS configuration to a terminal device in an RRC connected state via RRC signaling. The WUS configuration includes a frequency domain resource configuration indicating a plurality of frequency resources occupied by the WUS, and a time domain resource configuration indicating at least one of the periodicity of the WUS, the duty cycle of the WUS, and the number of OOK symbols mapped to the OFDM symbol, where the OOK symbol includes the at least one OOK on symbol and the at least one OOK off symbol, and the time domain resource configuration including a plurality of consecutive OFDM symbols within a slot or subframe used for the WUS, and a sequence configuration indicating at least one of the sequence length of the OOK symbol, the time interval of the OOK symbol, and the sequence ID indicating the OOK sequence from a plurality of predefined OOK sequences, including at least one of them.

[0223] In some embodiments, the method further includes reserving a guard band between the WUS and the normal DL transmission. The guard band is filled with one of the zero value, a value near zero, or a value based on the data of the normal DL transmission.

[0224] In some embodiments, the value near zero has less power than the non - zero value.

[0225] In another solution, the method implemented in the network device forms an OOK subsequence with a plurality of OOK symbols associated with one OFDM symbol, including at least one OOK on-symbol and at least one OOK off-symbol, maps the OOK subsequence to a plurality of pre-discrete Fourier transform (pre-DFT) subsequences respectively to form a pre-DFT sequence, performs transform precoding on the pre-DFT sequence, maps the output of the transform precoding to the frequency domain assigned to the wake-up signal (WUS) to generate the WUS, and transmits the WUS to the terminal device. The length of the pre-DFT subsequence among the plurality of pre-DFT subsequences is associated with at least one of the number of subcarriers used for the WUS, the number of the plurality of OOK symbols, or the index of the pre-DFT subsequence among the plurality of pre-DFT subsequences.

[0226] In some embodiments, generating the WUS further includes performing an inverse fast Fourier transform (IFFT) operation on the output of the transform precoding and the data for normal DL transmission, and inserting a cyclic prefix (CP) into the output of the IFFT operation, or performing an IFFT operation on the output of the transform precoding and inserting a guard interval (GI) before the output of the IFFT operation. The length of the GI is the same as the length of the CP, and the GI is one of zero-value samples, a dedicated sequence, a copy or transformation of a part of the output of an independent IFFT operation, or a CP.

[0227] In some embodiments, the length of the pre-DFT subsequence among the plurality of pre-DFT subsequences is further associated with at least one of the length of the OFDM symbol without the CP and the length of the CP. The difference in length between the first pre-DFT subsequence and any of the other pre-DFT subsequences is associated with the length of the CP.

[0228] In some embodiments, the length of the first pre-DFT subsequence is associated with at least one of the length of the pre-DFT subsequences other than the first pre-DFT subsequence and the number of subcarriers used for the WUS.

[0229] In some embodiments, the output of the independent IFFT operation includes a plurality of post-IFFT subsequences. Inserting the GI includes generating a GI sequence based on the first post-IFFT subsequence among the plurality of post-IFFT subsequences, or the first post-IFFT subsequence in reverse order, according to a determination that the first OOK symbol among the plurality of OOK symbols is an OOK on symbol; generating a GI sequence with a zero value or a value near zero according to a determination that the first OOK symbol among the plurality of OOK symbols is an OOK off symbol; or generating a GI sequence with the last post-IFFT subsequence among the plurality of post-IFFT subsequences according to a determination that the first OOK symbol and the last OOK symbol among the plurality of OOK symbols are the same, including one of them.

[0230] In some embodiments, according to the determination that a plurality of OOK sub-sequences are associated with a plurality of OFDM symbols, at least one of the plurality of OOK sub-sequences is a repetition of a first OOK sub-sequence among the plurality of OOK sub-sequences, or the plurality of OOK sub-sequences are generated based on the same sequence and are multiplied by two sets of coefficients respectively.

[0231] In some embodiments, forming the pre-DFT sequence further includes inserting padding data at the start or end of the pre-DFT sequence. The padding data is at least one of zero, a pre-defined sequence, or a copy of a part of the pre-DFT sub-sequence. The length of the padding data is determined based on at least one of the CP length and index of the OFDM symbol among the plurality of OFDM symbols, or an offset value.

[0232] In another solution, the network device includes a processor and a memory coupled to the processor and storing instructions, and when the instructions are executed by the processor, the method summarized above is performed.

[0233] In another solution, the method implemented in the terminal device further includes receiving a wake-up signal (WUS) from the network device and detecting the WUS to determine a plurality of on-off keying (OOK) symbols including at least one OOK on-symbol and at least one OOK off-symbol, where the at least one OOK on-symbol is generated based on a first number of frequency resources mapped with non-zero values used for normal downlink (DL) transmission, and the at least one OOK off-symbol is generated based on a second number of frequency resources mapped with zero values or values near zero.

[0234] In some embodiments, the WUS is generated based on an Orthogonal Frequency Division Multiplexing (OFDM) operation, which is used to generate normal DL transmissions.

[0235] In some embodiments, the above method further includes receiving, according to a determination that the terminal device is in a Radio Resource Control (RRC) idle or inactive state, a WUS setting in system information from the network device to monitor the WUS, or receiving, according to a determination that the terminal device is in an RRC connected state, a WUS setting via RRC signaling from the network device. The WUS setting includes at least one of a frequency domain resource setting indicating a plurality of frequency resources occupied by the WUS, a time domain resource setting indicating at least one of the periodicity of the WUS, the duty cycle of the WUS, and the number of OOK symbols mapped to OFDM symbols, where the time domain resource setting includes the at least one OOK on symbol and the at least one OOK off symbol, and a plurality of consecutive OFDM symbols within a slot or subframe used for the WUS, and a sequence setting indicating at least one of the sequence length of the OOK symbols, the time interval between the OOK symbols, and a sequence ID indicating an OOK sequence from a plurality of predefined OOK sequences.

[0236] In some embodiments, in response to not receiving the WUS setting from the network device, detecting the WUS is based on the assumption that the plurality of frequency resources for the WUS is at least one of a plurality of central physical resource blocks (PRBs) of a default bandwidth part (BWP), a plurality of upper edge PRBs of the default BWP, a plurality of lower edge PRBs of the default BWP, a plurality of central PRBs of a channel bandwidth, a plurality of upper edge PRBs of the channel bandwidth, or a plurality of lower edge PRBs of the channel bandwidth.

[0237] In some embodiments, detecting the WUS includes at least determining a time interval of a first OOK symbol of the plurality of OOK symbols based on a boundary between the first OOK symbol and a second OOK symbol of the plurality of OOK symbols.

[0238] In some embodiments, detecting the WUS includes determining a guard band reserved between the WUS and the normal DL transmission. The guard band is filled with one of the zero value or a value near zero, or a value based on data of the normal DL transmission.

[0239] In some embodiments, the value near zero has a lower power than the non-zero value.

[0240] In another solution, the method implemented in the terminal device includes receiving a wake-up signal (WUS) from a network device, detecting the WUS, and determining a plurality of on-off keying (OOK) symbols including at least one OOK on symbol and at least one OOK off symbol. The WUS is generated based on the output of the transform precoding of a pre-discrete Fourier transform (pre-DFT) sequence. The pre-DFT sequence includes a plurality of pre-DFT subsequences. The pre-DFT sequence is generated based on an OOK subsequence. The OOK subsequence includes the plurality of OOK symbols. The plurality of OOK symbols are associated with one OFDM symbol. The length of the pre-DFT subsequence among the plurality of pre-DFT subsequences is associated with at least one of the number of subcarriers used for the WUS, the number of the plurality of OOK symbols, or the index of the pre-DFT subsequence among the plurality of pre-DFT subsequences.

[0241] In some embodiments, receiving the WUS includes receiving the WUS and normal downlink (DL) transmission in a DL signal.

[0242] In some embodiments, the WUS and the normal DL transmission are generated by an inverse fast Fourier transform (IFFT) operation, and a cyclic prefix (CP) is inserted into the output of the IFFT operation, or the WUS is generated by an independent IFFT operation, and a guard interval (GI) is inserted into the output of the independent IFFT operation.

[0243] In some embodiments, the length of the pre-DFT subsequence among the plurality of pre-DFT subsequences is further associated with at least one of the length of an OFDM symbol without CP and the length of the CP. The difference in length between the first pre-DFT subsequence and any of the other pre-DFT subsequences is associated with the length of the CP.

[0244] In some embodiments, the length of the first pre-DFT subsequence is associated with at least one of the length of the pre-DFT subsequences other than the first pre-DFT subsequence and the number of subcarriers used for WUS.

[0245] In some embodiments, the output of an independent IFFT operation includes a plurality of post-IFFT subsequences. The GI, according to the determination that the first OOK symbol among the plurality of OOK symbols is an OOK on-symbol, the GI sequence is generated based on the first post-IFFT subsequence among the plurality of post-IFFT subsequences, or the first post-IFFT subsequence in reverse order; according to the determination that the first OOK symbol among the plurality of OOK symbols is an OOK off-symbol, the GI sequence is generated with a zero value or a value near zero; or according to the determination that the first OOK symbol and the last OOK symbol among the plurality of OOK symbols are the same, the GI sequence is generated based on the last post-IFFT subsequence among the plurality of post-IFFT subsequences, based on at least one of these.

[0246] In some embodiments, at least one of the plurality of OOK subsequences is a repetition of the first OOK subsequence among the plurality of OOK subsequences, or the plurality of OOK subsequences are generated based on the same sequence and each is multiplied by two sets of coefficients.

[0247] In some embodiments, WUS is generated based on the output of the transform precoding of a pre-DFT sequence with padding data inserted at the start or end. The padding data is at least one of zero, a predefined sequence, or a copy of a part of the pre-DFT subsequence. The length of the padding data sequence is determined based on at least one of the CP length and index of the OFDM symbols among a plurality of OFDM symbols, or an offset value.

[0248] In another solution, a method implemented in a terminal device is to receive, from a network device, a downlink (DL) signal including a wake-up signal (WUS) and a normal downlink (DL) transmission, where the LP-WUS and the normal DL transmission are generated using an Orthogonal Frequency Division Multiplexing (OFDM) operation, receive a WUS setting from the network device, determine a resource for the WUS indicated in the WUS setting, determine an overlapping resource that is allocated to the normal DL transmission and overlaps with the resource for the WUS, and determine that the overlapping resource is not available for the normal DL transmission.

[0249] In some embodiments, the WUS includes a plurality of On-Off Keying (OOK) symbols. The WUS configuration includes at least one of a frequency domain resource configuration indicating a plurality of frequency resources occupied by the WUS, a time domain resource configuration indicating at least one of the periodicity of the WUS, the duty cycle of the WUS, and the number of OOK symbols mapped to OFDM symbols, where the OOK symbols include the at least one OOK on symbol and the at least one OOK off symbol, and the time domain resource configuration includes a plurality of consecutive OFDM symbols within a slot or subframe used for the WUS, and a sequence configuration indicating at least one of the sequence length of the OOK symbols, the time interval of the OOK symbols, and a sequence ID indicating an OOK sequence from a plurality of predefined OOK sequences, and includes at least one of them.

[0250] In another solution, a method implemented in a terminal device is to receive, from a network device, a downlink (DL) signal including a wake-up signal (WUS) and a normal downlink (DL) transmission, where the WUS includes a plurality of On-Off Keying (OOK) symbols including at least one OOK on symbol and at least one OOK off symbol, the at least one OOK on symbol is generated based on data of the normal DL transmission, determining indexes of a plurality of physical resource blocks (PRBs) assigned to the WUS, determining that resource elements (REs) of the plurality of PRBs of the OFDM symbols associated with the OOK on symbols are available for the normal DL transmission, and determining that the REs of the plurality of PRBs of the OFDM symbols associated with the OOK off symbols are not available for the normal DL transmission.

[0251] In another solution, the terminal device includes a processor and a memory coupled to the processor and storing instructions, and when the instructions are executed by the processor, the method summarized above is performed.

[0252] In another solution, a computer-readable medium stores instructions that, when executed on at least one processor, cause the at least one processor to perform the method summarized above.

Claims

1. A method for transmitting a setting indicating the number of On-Off Keying (OOK) symbols in an Orthogonal Frequency Division Multiplexing (OFDM) symbol for a low-power signal to a terminal device; means for generating a first sequence, the length of which is determined based on the setting and the number of subcarriers used for the low power signal; means for generating the low power signal based on the first sequence.

2. The network device described in claim 1, wherein the first sequence is a Zadoff-Chu (ZC) sequence.

3. means for determining an OOK sequence based on said setting; The network device of claim 1 , further comprising: means for generating the low-power signal based on the OOK sequence.

4. The network device of claim 3, wherein at least one OOK-ON symbol in the OOK sequence is reused in normal downlink (DL) transmission.

5. A method for generating a second sequence associated with a plurality of OOK symbols corresponding to an OFDM symbol, wherein an end portion of the second sequence is set to a fixed value; 10. The network device of claim 1, further comprising: means for transmitting a signal determined based on the second sequence to an internet of things (IoT) device.

6. A method for transmitting a low-power signal comprising: means for receiving from a network device a setting indicating a number of On-Off Keying (OOK) symbols within an Orthogonal Frequency Division Multiplexing (OFDM) symbol for a low-power signal; and means for receiving from the network device the low-power signal based on a first sequence, the length of which is determined based on the setting and the number of subcarriers used for the low-power signal.

7. The terminal device described in Claim 6, wherein the first sequence is a Zadoff-Chu (ZC) sequence.

8. A terminal device as described in claim 6, wherein an OOK sequence is determined based on the setting, and the low-power signal is generated based on the OOK sequence.

9. The terminal device of claim 8, wherein at least one OOK-ON symbol in the OOK sequence is reused in normal downlink (DL) transmission.

10. A terminal device as described in claim 6, further comprising means for receiving from the network device a signal determined based on a second sequence associated with a plurality of OOK symbols corresponding to OFDM symbols, and an end portion of the second sequence is set to a fixed value.

11. Transmitting a setting to a terminal device indicating a number of On-Off Keying (OOK) symbols within an Orthogonal Frequency Division Multiplexing (OFDM) symbol for a low-power signal; generating a first sequence having a length determined based on the setting and the number of subcarriers used for the low power signal; A method implemented in a network device that generates the low power signal based on the first sequence.

12. The method of claim 11, wherein the first sequence is a Zadoff-Chu (ZC) sequence. determining an OOK sequence based on the setting; The method of claim 11 , wherein the low-power signal is generated based on the OOK sequence.

14. The method of claim 13, further comprising: generating a second sequence associated with a plurality of OOK symbols corresponding to the OFDM symbols, wherein an end portion of the second sequence is set to a fixed value; The method of claim 11 , further comprising transmitting a signal determined based on the second sequence to an internet of things (IoT) device.

15. A method for transmitting a low-power signal comprising: receiving from a network device a configuration indicating a number of On-Off Keying (OOK) symbols within an Orthogonal Frequency Division Multiplexing (OFDM) symbol for a low-power signal; A method implemented in a terminal device, receiving from the network device the low power signal based on a first sequence, the length of which is determined based on the setting and the number of subcarriers used for the low power signal.

Images