Radio Wake-up Signal

Abstract

An Orthogonal Frequency-Division Multiple-Access (OFDMA) radio signal (106) is transmitted, the radio signal (106) having information digitally modulated as OFDMA symbols on subcarriers in a first symbol period. The radio signal (106) includes a set of second symbol periods interleaved in time with the set of first symbol periods, where the subcarriers are unmodulated, to create a predetermined time sequence pattern (221). The radio signal (106) is received at a first radio device (101) which demodulates and uses information from the modulated symbol periods of the predetermined time sequence pattern. A second radio device (104) receives the same radio signal (106) and detects the predetermined time sequence pattern (221) of modulated and unmodulated symbol periods in the received radio signal, and in response thereto, wakes up a radio module (200) of the second radio device (104) by generating a wake-up electrical signal.

Description

[Technical field]

[0001] The present invention relates to wake-up signals in Orthogonal Frequency-Division Multiple-Access (OFDMA) wireless systems. [Background technology]

[0002] Transceiver devices in a multiple access wireless system can conserve power by entering a lower power consumption "sleep" state when they are not actively receiving information over the wireless channel. This involves powering down some of the receiving circuitry (e.g., the wireless transceiver circuitry). It is well known that to awaken a sleeping device, a relatively simple "wake-up signal" can be sent to the device, which the device effectively recognizes while in a sleeping state. After detecting this wake-up signal, the sleeping device enters a awake state and is able to exchange more complex information over the wireless system.

[0003] For example, Non-Patent Document 1 describes a wake-up frame in the IEEE802.11ba standard. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] "IEEE802.11b a Wake-Up Radio: Performance Evaluation and Practical Designs" by Deng et al., IEEE Access (2020) Summary of the Invention [Problem to be solved by the invention]

[0005] Wake-up signals can facilitate reduced power consumption by receiving devices, but transmission of wake-up signals in orthogonal frequency division multiple access (OFDMA) wireless systems can undesirably occupy valuable bandwidth.

[0006] Embodiments of the present invention seek to address this problem. [Means for solving the problem]

[0007] According to a first aspect, the present invention provides a method of operating a wireless system, the method comprising: transmitting an Orthogonal Frequency-Division Multiple-Access (OFDMA) wireless signal, the wireless signal including information digitally modulated as one or more OFDMA symbols onto one or more subcarriers in a first set of one or more symbol periods and time interleaved with the first set of one or more symbol periods in a second set of one or more symbol periods, one or more of the subcarriers being unmodulated to provide a predetermined time sequence pattern of modulated and unmodulated symbol periods across the one or more subcarriers; receiving the wireless signal at a first wireless device of the wireless system, the first wireless device demodulating and using information from one or more modulation symbol periods of the predetermined time sequence pattern; receiving the wireless signal at a second wireless device of the wireless system, detecting a predetermined time sequence pattern of modulated symbol periods and non-modulated symbol periods in the received wireless signal; and in response to detecting the predetermined time sequence pattern in the received radio signal, the second radio device generates a wake-up electrical signal to activate a radio module of the second radio device.

[0008] According to a second aspect, the present invention provides a wireless system including a base station, a first wireless device, and a second wireless device, the base station is configured to transmit an Orthogonal Frequency Division Multiple Access (OFDMA) wireless signal, the wireless signal including information digitally modulated as one or more OFDMA symbols onto one or more subcarriers in a first set of one or more symbol periods, and sending a predetermined time sequence pattern of modulated and unmodulated symbol periods across the one or more subcarriers in a second set of one or more symbol periods time interleaved with the first set of one or more symbol periods, one or more of the subcarriers being unmodulated; The first wireless device receives the wireless signal and demodulates and uses information from one or more symbol periods in the first set of symbol periods; and The second radio device is configured to receive the radio signal, detect the predetermined time sequence pattern of modulated symbol periods and symbol periods that remain unmodulated in the received radio signal, and generate a wake-up electrical signal to activate a radio module of the second radio device in response to detecting the predetermined time sequence pattern in the received radio signal.

[0009] According to a third aspect, the present invention provides a radio device for use in a radio system, the radio device comprising: a radio module and a wake-up unit; the wireless module has a wake state and a sleep state; The wireless device includes: receiving a plurality of Orthogonal Frequency Division Multiple Access (OFDMA) wireless signals, each wireless signal comprising information digitally modulated as one or more OFDMA symbols onto one or more subcarriers in a first set of one or more symbol periods, and one or more of the subcarriers remaining unmodulated in a second set of one or more symbol periods interleaved in time with the first set of one or more symbol periods, the second set of one or more symbol periods comprising a predetermined time sequence pattern of modulated and unmodulated symbol periods across the one or more subcarriers; receiving a first of the wireless signals when the wireless module is in the wake state, and using the wireless module to demodulate and use information from one or more of the first set of symbol periods of the first wireless signal; When the radio module is in the sleep state, it receives a second radio signal, detects a predetermined time sequence pattern of modulated and unmodulated symbol periods in the second radio signal using the wake-up unit, and in response to detecting the predetermined time sequence pattern in the second radio signal, transmits a wake-up electrical signal from the wake-up unit to the radio module to cause the radio module to enter the wake state.

[0010] Thus, it can be seen that, according to an embodiment of the present invention, the same modulation symbols of an OFDMA wireless signal can be used to both transmit data to one wireless device and wake up another wireless device. Similarly, the same wireless device can wake up in response to receiving one of the wireless signals (which may be simultaneously transmitting information to another wireless device) and use (e.g., decode) information from a subsequent one of the wireless signals (which itself may be used to wake up another wireless device). In the first and second sets of symbol periods arranged in the predetermined time sequence pattern, a new type of wireless wake-up signal is provided that does not need to consume resource overhead compared to a wake-up signal that does not communicate any useful additional information.

[0011] The OFDMA wireless signal(s) may be transmitted from a base station. The system may be any type of OFDMA wireless system. The system may be a cellular long range communication system supporting 4G or 5G wireless standards. The wireless signal(s) may conform to current or future 5G New Radio (NR) specifications. The information is modulated using any modulation scheme, and in some embodiments is modulated using Quadrature Amplitude Modulation (QAM). Each modulation symbol period includes a respective QAM symbol. The symbol periods may all be of equal length.

[0012] The first modulated set of symbol periods includes a number of symbol periods, at least two of which are separated in time by one symbol period of the second set. The second unmodulated set of symbol periods includes a number of symbol periods, at least two of which are separated in time by one symbol period of the first set. The modulated and unmodulated sets of symbol periods may be interleaved. The time sequence pattern may be of any length, for example 4, 8, 16, 32 or more symbol periods. It may conform to a Gold code, a Walsh code, a Barker code, a Hadamard code, a Kazami code, an M-sequence code, or any other binary pattern with strong autocorrelation properties, where one set of symbol periods corresponds to a "1" bit and the other set of symbol periods corresponds to a "0" bit.

[0013] By transmitting unmodulated symbols within the wake-up signal, the wireless signal can be made to contain no, or only negligible (e.g., not significantly above the noise floor of the wireless system) energy within the second set of symbols, thereby allowing the wireless device to efficiently detect the wake-up signal.

[0014] The second wireless device includes a wireless module (e.g., a wireless transceiver) and a wake-up unit. In any of the aspects disclosed herein, the wireless module has a wake state and a sleep state, which correspond to the wake state and the sleep state of the wireless device. The wake-up unit is configured to detect when a wake-up signal (i.e., a wireless signal including the predetermined time sequence pattern) is received by the wireless device. The wake-up unit can be a separate unit from the wireless module. The wake-up unit can be active when the wireless module is in the sleep state. The wake-up unit can be inactive when the wireless module is in the wake state, but this is not required.

[0015] A wireless device (e.g., a second wireless device), or a wake-up unit thereof, can detect the predetermined time series pattern by determining a time series of energy values, each of which is indicative of the energy of a wireless signal received by the wireless device at a respective time. The wireless device can determine a correlation value by cross-correlating the time series of energy values ​​with data representative of the predetermined time series pattern. The wireless device can determine whether the correlation value satisfies a wake-up condition and in response generate a wake-up electrical signal.

[0016] The wake-up unit includes an envelope detector for determining a time series of energy values. The envelope detector includes an analog circuit, e.g., a rectifier circuit. The envelope detector further includes a digital circuit for determining an energy value. The envelope detector is configured to sample the received energy across one or more subcarriers to determine the energy value. The envelope detector measures a total received energy across one or more subcarriers. The envelope detector samples the received energy at least once per symbol period for a first and second set of symbol periods. The wake-up unit includes a correlator for performing cross-correlation.

[0017] The wake-up unit includes a memory for storing data representative of a predefined time sequence pattern. The data may be permanently stored in the memory, e.g. from manufacture, or the wireless device may be configured to receive the data representative of the predefined time sequence pattern in a radio signal that is decoded by the radio module. The wake-up unit may be connected to the radio module by a data channel to receive configuration data (e.g. the data representative of the predefined time sequence pattern) from the radio module. The memory may store a plurality of predefined time sequence patterns, and the wireless device may cross-correlate the time series of energy values ​​with the data representative of each of the predefined time sequence patterns.

[0018] The wake-up unit may be connected to the wireless module by a wake-up line for transmitting a wake-up signal to the wireless module.

[0019] The radio module may be provided by a semiconductor chip. The wake-up unit may be integrated on this chip or may be separate. The wake-up unit may also be provided by a separate wake-up semiconductor chip.

[0020] The radio module may include logic for decoding information from the received radio signal using a Fast Fourier Transform (FFT). In contrast, the wake-up unit preferably does not have FFT logic and instead uses a correlator to detect the wake-up signal. The wake-up unit preferably consumes less power when active than the radio module consumes when decoding the radio signal. Thus, power can be saved by using a wake-up signal according to embodiments of the present invention when the device is in a sleep state.

[0021] The first device may use (e.g., decode) all of the information modulated in the first set of one or more symbol periods, or may use only a portion of it. For example, the information may be used in some manner, such as decoding the data for further processing or to perform training or calibration operations (such as estimating signal strength or signal-to-noise ratio). One or more further wireless devices may demodulate and use the information from the first set of one or more symbol periods. These symbol periods may be the same modulation symbol periods used by the first device (e.g., if the wireless signal is used to transmit a message to a group of devices) or may be different modulation symbol periods from the first set of symbol periods (e.g., if different messages in the same wake-up signal are transmitted to different devices).

[0022] The wireless signal may transmit digitally modulated information including control information or device specific data. Configuration information specifying frequency-time resource units in which the wireless devices should decode information may be transmitted (e.g., encoded in the wireless signal) to one or more wireless devices. In particular, the configuration information is transmitted to a first wireless device, and a part or all of a first set of one or more symbol periods is assigned to the first wireless device on one or more subcarriers. The first set of one or more symbol periods may be assigned across one or more time slots (e.g., 5G New Radio (NR) slots). The wireless signal may include resource unit allocation control information (e.g., Downlink Control Information (DCI)), which may be followed in time by device specific data (e.g., Physical Downlink Shared Channel (PDSCH) data) in the allocated resource units. The resource unit allocation control information may allocate resource units of the wireless device on one or more subcarriers in a first set of one or more symbol periods (i.e., within the wake-up signal) and / or may allocate other resource units (i.e., outside the wake-up signal). The resource unit specification may be achieved by offsetting the number of symbols to wait in time following receipt of the resource unit allocation control information.

[0023] During certain times, the base station may not need to transmit a wake-up signal. In such cases, the symbol periods that are not modulated as part of the wake-up signal may instead be allocated for downlink information. Thus, the symbol periods of the second set of one or more symbol periods may have respective time positions relative to the first instance of the resource unit allocation control information in the wireless signal, and configuration information indicating the allocation of another set of symbol periods having equal time positions relative to the second instance of the resource unit allocation control information may be transmitted on one or more subcarriers to the first wireless device for reception at the first wireless device.

[0024] The wake-up signal may be encoded on a single subcarrier, but is preferably encoded on multiple subcarriers, i.e., the one or more subcarriers are preferably two or more subcarriers. In this way, the difference in total modular energy across multiple subcarriers between modulated and non-modulated symbol periods can be increased. This can improve the accuracy of cross-correlation. Different symbols can be encoded on two or more subcarriers in the same symbol period. This allows more information to be communicated within the wake-up signal. However, preferably, the non-modulated symbol period is demodulated across multiple subcarriers.

[0025] The one or more subcarriers are preferably a plurality of consecutive subcarriers. This can simplify energy detection in the wake-up unit, which can have a frequency filter for passing the plurality of consecutive subcarriers. The wake-up unit can be configured to sample the aggregate energy across the plurality of consecutive subcarriers. The one or more subcarriers preferably span fewer than all subcarriers of an OFDMA frequency band of the wireless system (e.g. a predefined carrier bandwidth). The wireless signal can include further information digitally modulated onto other subcarriers and / or other symbol periods of the OFDMA frequency band.

[0026] The predetermined time sequence pattern may be continuous or may extend over a number of spaced apart time intervals, which may be separated by one or more time gaps (e.g., in which the modulation states of resource units are variable). The second radio device or wake-up unit may exclude energy values ​​corresponding to the one or more time gaps when performing cross-correlation.

[0027] Each wireless device may be any wireless device, such as a wireless sensor, an industrial machine, a vehicle, a home appliance, or a mobile phone.

[0028] Features of an aspect or embodiment described herein may be applied to any other aspect or embodiment described herein, where appropriate. Reference to different embodiments or sets of embodiments should be understood to be made to these not necessarily separate and may overlap. [Brief description of the drawings]

[0029] Certain preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] 1 is a schematic diagram of a multi-device wireless system embodying the present invention; [Diagram 2] FIG. 2 illustrates a wireless device of the multi-device wireless system. [Diagram 3] FIG. 2 is a resource grid diagram for a representative example wireless signal transmitted in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] FIG. 1 illustrates a multi-device wireless system 100 embodying the present invention. System 100 may be a cellular telecommunications system, supporting current or future mobile communication standards. Wireless system 100 is comprised of a number of User Equipment (UE) devices 101-104 within wireless range of a base station 105. UE devices 101-104 may include mobile phones, wireless sensors, machines, vehicles, household appliances, etc. Base station 105 may be a component of a long-range communications network 107, which also includes a backhaul network that may connect to other base stations, as well as a mobile core and other conventional components. System 100 may also include other UE devices.

[0031] The base station 105 can transmit information to the UE devices 101-104 by downlink radio signal 106 using digital modulation according to an Orthogonal Frequency Division Multiple Access (OFDMA) scheme. The signal 106 is modulated on multiple subcarrier frequencies within the OFDMA frequency band (i.e., within the total carrier bandwidth). The OFDMA frequency band is also divided into multiple discrete time intervals, forming a grid of physical frequency-time resource units distributed across both time and frequency. Each resource unit is described by various names in different OFDMA systems (e.g., "resource element" or "resource block"), but occupies a set of one or more frequency-contiguous subcarriers (e.g., 12 subcarriers for a 4G or 5G physical resource block (PRB)) and a predetermined number of Orthogonal Frequency Division Multiplexing (OFDM) symbol time intervals (e.g., 1 symbol for 5G, 7 symbols for 4G), and is the smallest time-frequency resource allocated (i.e., scheduled) by the network 107 for communicating information to the UE devices 101-104. OFDM symbols may also be modulated using Quadrature Amplitude Modulation (QAM), e.g., with resource units each encoding one bit using Binary Phase-Shift Keying (BPSK) or resource units each encoding eight bits using 256QAM. The telecommunications network 107 may dynamically allocate a set of resource units to one or more UEs 101-104 and transmit information to the UE or UEs on the allocated resource units.

[0032] At least some of the UE devices 101-104 have a wake state and a sleep state, and are designed to use less power when in the sleep state than when in the wake state, in particular to conserve electrical energy by powering down some of the radio transceiver circuitry when in the sleep state, although the UE device must be placed in the wake state in order to decode information transmitted by the base station 105.

[0033] During the particular period shown in FIG. 1, three of the UE devices, 101-103, are in a wake state and one UE device, 104, is in a sleep state.

[0034] 2 shows a schematic diagram of a representative example of a UE device 104 that can be switched between a wake state and a sleep state. The UE device 104 comprises a radio module 200 and a wake-up unit 201, each of which is electrically connected to a radio antenna 202 of the UE device 104.

[0035] The radio module 200 includes standard radio transceiver circuitry capable of decoding OFDMA signals, including OFDMA signal 106 from the base station 105. The radio transceiver circuitry includes logic for performing a Fast Fourier Transform (FFT) on radio signals received at antenna 202 and processing the transformed data to decode information from an assigned set of resource units. It also includes circuitry for transmitting uplink signals to the base station 105.

[0036] The wake-up unit 201 is also connected to an antenna 202, but in contrast to the radio module 200, it does not contain FFT logic for decoding information from the received signal, but instead contains an envelope detector 203, a correlator 204, a memory 205 and control logic 206. The correlator 204 can also be implemented in software, but in this embodiment it is a hardware correlator.

[0037] The radio module 200 and the wake-up unit 201 may be integrated on a common semiconductor chip, but in some embodiments the radio module 200 is provided by a semiconductor radio transceiver chip and the wake-up unit 201 is separate, for example provided by a discrete circuit or as a semiconductor wake-up chip. The radio module 200 is electrically connected to the wake-up unit 201 by a wake-up signal line 210 and a configuration data channel 211.

[0038] When the UE device 104 is in a sleep state, the radio module 200 does not decode the incoming radio signal 106 transmitted from the base station 105. Instead, the signal 106 is processed by the wake-up unit 201 to detect when the signal 106 contains a predefined wake-up signal, which is transmitted from the communication network 107 via the base station 105 before transmitting downlink information to the device 4, and which triggers the device 4 to leave the sleep state and enter the wake state.

[0039] The UE device 104 is configured with a predefined set of resource units on which the wake-up signal is transmitted. The wake-up unit 201 detects the wake-up signal by listening to a predefined pattern of radio energy transmitted by these wake-up resource units. Since the wake-up unit 201 does not demodulate and decode the OFDMA signal 6 it receives, it consumes much less energy than the radio module 200 consumes when it is actively receiving information over the air. Compared to the radio module 200, the wake-up unit 201 does not require a more precise synchronization, which can further reduce the complexity and power consumption of the unit.

[0040] The predetermined wake-up physical resource units may have been communicated to the UE device 104 (e.g., in a 5G SIB (System Information Block)) when the UE device 104 was previously in a wake state and may have been received by the radio module 200.

[0041] When the UE device 104 is in a sleep state, the wake-up unit 201 constantly checks whether a wake-up signal has been received by the UE device 104. After appropriate tuning and filtering, the received Radio Frequency (RF) spectrum is sent to an envelope detector 203 which repeatedly samples the received signal strength over the frequency range of the subcarriers of the wake-up physical resource. The received signal is filtered such that the envelope detector samples only the signal strength over the frequency range of the subcarriers of the wake-up physical resource. The subcarriers used for the wake-up physical resource can be contiguous in frequency and only one filter is needed to limit the sampled frequency range. If the subcarriers are not contiguous but are split across the entire OFDM spectrum, multiple filters would be needed, increasing the complexity required of the wake-up unit 201. Resource units containing modulated symbols are determined to have a relatively high received energy, e.g., greater than -72 dBm, whereas unmodulated resource units are determined to have a relatively low received energy, since they carry only background noise. The envelope detector 203 outputs a sample stream representing a time series pattern 220 of received energy of wake-up resource units, which varies depending on which wake-up resource units contain modulated symbols and which do not. The time series pattern 220 of received energy is then sent to a correlator 204. The correlator 204 cross-correlates the received time series pattern 220 with sample data representing a predetermined expected wake-up pattern 221 stored in a memory 205.If a given wake-up physical resource block is not contiguous in time, the correlator 204 may be configured to correlate only energy samples corresponding to the symbol period of the wake-up resource unit (i.e., filter and output energy samples from the envelope detector 203 from time intervals that are outside of the given wake-up resource unit).

[0042] The control logic 206 coordinates the operation of the components of the wake-up unit 201. In particular, the control logic 206 may configure the correlator 204 with predefined wake-up resource blocks and symbols that constitute a resource unit, such as based on configuration data 230 received from the radio module 200 via the data channel 211. The control logic 206 may include a processor and software, or may implement a finite state machine in hardwired digital logic.

[0043] The use of energy envelope detection limits the power that the wake-up unit 201 needs to use to detect the wake-up signal, thereby avoiding the need for processes such as Fourier transforms, which require more complex logic and consume more power, to decode the received signal 6. This use of envelope detection effectively uses On-Off Keying (OOK) to detect the wake-up pattern 221 as a binary string, rather than a more complex decoding process.

[0044] The expected wake-up pattern 221 may be preloaded into the memory 205 when the device is manufactured or together with a firmware update. Alternatively, the expected wake-up pattern may be pre-sent to the UE device 104 by the telecommunications network 107 when the UE device 104 is in a awake state and connected to the network. Thus, the control logic 206 is configured to receive configuration data 230 encoding an updated wake-up pattern from the radio module 200 via the configuration data channel 211 and store it in the memory 205.

[0045] The correlator 204 outputs the correlation strength information (e.g., as a stream of correlation coefficients) to the control logic 206, which may detect the correlation peak in any suitable manner, such as detecting when the correlation strength exceeds a predetermined threshold. If the correlation between the received time series pattern of the signal energy 220 and the expected wake-up pattern 221 indicates a match, the control logic 205 causes a wake-up command signal 231 to be transmitted from the wake-up unit 201 to the radio module 200 through the wake-up line 210. Alternatively, the wake-up command signal 231 may be transmitted to a separate power management unit of the device 104, which may then wake up the radio module 200. The radio module 200 enters a wake-up state and powers up a receiving circuit for demodulating the incoming OFDMA signal 106. The UE device 104 is then back in the wake state, ready to receive and decode information from the base station 105. Upon waking up, the radio module begins listening for calls and / or communicating with the network.

[0046] Importantly, this approach does not depend on any particular OFDM symbol being modulated onto the non-silent resource units of the wake-up signal, allowing the base station 105 to use the exact same resource units to both wake up the sleeping UE device 104 and to transmit useful information to one or more other UE devices 101-103. This allows for a very efficient allocation of spectrum resources, particularly in standard spectrum where there is typically an economic cost associated with the use of spectrum bandwidth.

[0047] FIG. 3 illustrates a representative example of a resource allocation grid 300 for a portion of a 5G downlink Orthogonal Frequency Division Multiple Access (OFDMA) signal, which corresponds, for example, to an OFDMA signal 106 transmitted by a base station 105. In 5G New Radio (NR), frequency-time resources in the 5G spectrum are allocated at the granularity of individual Physical Resource Blocks (PRBs) in the frequency domain (each resource block occupies 12 subcarriers) and at the granularity of individual OFDM symbol periods in the time domain. The resource grid 300 of FIG. 3 represents 19 PRBs along the frequency axis, 56 symbol periods along the time axis, and defines consecutive NR (New Radio) slots 301 every 14 OFDM symbol periods "0-13", with the grid 300 illustrated herein representing four NR slots 301a-301d.

[0048] Some of the resource allocation locations 302-304 of the transmitted OFDMA signal 106 are allocated for transmitting Physical Downlink Control Channel (PDCCH) information. The awake UE devices 101-103 attempt to decode the PDCCH signal to obtain the Downlink Control Information (DCI). The DCI indicates to each UE device 101-103 the allocation of which resources are allocated to the Physical Downlink Shared Channel (PDSCH). For example, the DCI of the first PDCCH 302 may indicate, among other control information, the location of a large "legacy" PDSCH resource allocation 310 for the first UE 101 and a small PDSCH resource allocation 320 for the second UE 102. The second PDCCH 303 may communicate the location of the large "legacy" PDSCH resource allocation 311 for the second UE 102 and the small allocation 321 for the first UE 101, while the third and fourth PDCCHs 304, 305 may communicate the location of the PDSCH resource allocations 312, 322, 313, 323 in all third and fourth slots for the third UE 103. In this example, each PDCCH allocates resources in its own slot 301, but the PDCCH may instead indicate a non-zero slot offset from the DCI of the PDCCH to the PDSCH (i.e., to allocate resources in subsequent slots). The allocated PDSCH resources may be used to transmit user data and / or paging information to the UE devices. In this manner, PDSCHs may be allocated across the resource grid to different UE devices 101-103.

[0049] More specifically, in the example of FIG. 3, the first UE device 101 is assigned a “legacy” rectangle 310 of resource units occupying PRBs “5-18” and symbol periods “3-13” of the first slot 301a. However, the first UE device 101 is further assigned a set 321 of resource units occupying PRBs “0-3” and symbol periods “3, 8, 9, 10, 12” of the second slot, which form part of the novel wake-up signal 330 disclosed herein. The second UE device 102 is assigned a “legacy” rectangle 311 of resource units occupying PRBs “5-18” and symbol periods “3-13” of the second slot 301b, and is also assigned a set 320 of resource units occupying PRBs “0-3” and symbol periods “7, 9, 10, 12” of the first slot. A third UE device 103 is assigned a large "legacy" rectangle of PRBs 312, 313 and a smaller set of PRBs 322, 323 in the third and fourth slots 301c, 301d.

[0050] The small set of resources 320-323 assigned to the three UE devices 101-103 may communicate information (e.g., data and paging information) to these devices 101-103, but these sets of resources 320-323 also form part of a wake-up signal 330 for signaling the fourth UE device 104 to wake up from a sleep state and enter a wake-up state.

[0051] The physical resources for the wake-up signal 330 are allocated across 32 OFDM symbol periods divided into four non-contiguous time intervals of 10 symbol periods as shown in Figure 3, such that a sequence of unmodulated (silence) resource units (labelled with "0" in Figure 3) is interleaved in time with a sequence of modulated resource units 320-323 according to a predefined wake-up pattern 221. In this example, the wake-up signal 330 spans four slots 301a-301d separated by the second, third and fourth PDCCHs, 303, 304, 305. This example has the 32-bit pattern [00010110101000111010111100100110] as a typical example, but other wake-up signals can use any binary pattern with good autocorrelation properties, such as Gold codes, Walsh codes, Barker codes, Hadamard codes, Kasami codes, or M-sequence codes, and can be of different bit lengths.

[0052] If the wake-up signal 330 is transmitted multiple times with the same time sequence pattern, the resource has the same relative position in time for each transmission. For example, the Demodulation Reference Signal (DMRS) for the allocation of the wake-up signal 330 may always be placed in the first modulated OFDM symbol period of the slot-based allocation in the selected wake-up pattern, but the location of the DMRS for PRBs outside the wake-up signal may be determined by legacy methods (e.g., according to the current 5G NR specifications).

[0053] In the third slot 301c, PDSCH allocations are made for the third UE device 103 both within and outside the wake-up signal 330. In this case, it is not essential that the DMRS symbols within and outside the wake-up signal 330 have the same position in time. For example, the DMRS symbol of the wake-up signal 330 is always assigned to the first modulated OFDM symbol, but the positions of the DMRS of the other assigned PRBs 312 can be determined by legacy methods.

[0054] To detect this wake-up signal 330, the envelope detector 203 in the wake-up unit 201 detects energy at frequencies corresponding to the subcarriers of PRBs "0-3". In response to receiving the OFDM signal shown in the grid 300, the envelope detector 9 will output low sample values ​​during the unmodulated symbol periods (labelled "0" in FIG. 3) of the wake-up signal 330 and high sample values ​​during the modulated symbol periods 320-323. The correlator 204 is controlled to correlate the energy samples taken in symbol periods "4-13" of each successive slot 301 against stored template data representing the expected energy level of the wake-up signal 330. The correlator 204 ignores the energy sample values ​​from within the time periods of the PDCCH 303, 304.

[0055] As can be seen from Fig. 3, the modulated allocations 320-323 in the wake-up signal 330 are used to signal the sleeping UE device 104 and are also used as PDSCH for the other UE devices 101-103. For example, the resource unit 322 is used for the PDSCH of the third UE device 103, which then outputs a HARQ-ACK in response to receiving the PDSCH. In contrast, the envelope detector 109 of the wake-up unit 201 does not decode the information transmitted in the allocated wake-up physical resources 320-323. Therefore, it does not matter what information is modulated onto the signals in the modulated allocations 320-323, only that there is radio energy transmitted on those subcarriers and symbol periods.

[0056] Using the modulated allocations 320-323 of the wake-up signal 330 to transmit PDSCH data or paging information to other UE devices 101-103 allows for very efficient use of the resource grid 300. Thus, the use of energy sequences for the wake-up signal 330 not only reduces the power and complexity of the wake-up unit 201, but also reduces the resource overhead of the entire wireless system 100.

[0057] If there is no need to transmit a wake-up signal 330 (e.g., if the fourth UE device 104 is already awake), a Time Domain Resource Allocation (TDRA) field of the DCI information may indicate that all symbol periods of the physical resource used for the wake-up signal 330 may be used for PDSCH allocation. An allocation protocol for resource allocation that does not take into account the wake-up signal may be invoked for periods when the base station 105 does not need to transmit a wake-up signal 330.

[0058] The UE device must support networks 107 that implement the wake-up mechanism of the present application as well as networks that do not. Legacy networks do not need to be configured to allocate PDSCHs interspersed within the wake-up signal 330, but only support the "legacy" allocation of larger PDSCH blocks. To signal to compatible UE devices that the network 107 supports the allocation of wake-up signals, the Resource Allocation (RA) field of the DCI format may be expanded by one bit (e.g., before the Time Domain Resource Allocation (TDRA) field) compared to the current 5G specification, which is used to signal to the UE device whether the network is allocating wake-up signal resources or only legacy resource allocations.

[0059] Alternatively or additionally, if the indicated legacy resource allocation (RA) field overlaps with the resource blocks and symbols of the wake-up signal resources, the UE device may send an additional indication as to whether the PDSCH is rate matched within the unmodulated ("0") symbols of the wake-up signal in the slot.

[0060] Although the wake-up signal 330 is described herein as being sent to wake up a single UE device 104, the same signal can be used to wake up multiple UE devices simultaneously, so long as the multiple UE devices are configured to correlate against stored data representing the same predefined time series pattern (e.g., by the network 107 sending appropriate template data that is stored in the local memory 205 of the wake-up units 201 of the multiple UE devices before the multiple UE devices go to sleep).

[0061] In some embodiments, a UE device 104 may be configured to detect any of a number of wake-up signals, each having a different OOK pattern. This allows the UE device to be a member of a number of different device groups, each of which may be woken up by a different wake-up signal. If asleep, the UE device cross-correlates the received signal energy against all the patterns and wakes up if any of the patterns match. Data representing each pattern may be stored in the memory 205 of the wake-up unit 201.

[0062] In some embodiments, all UE devices may be configured with the same library of wake-up signal patterns, and when allocating resources in the wake-up signal, the network 107 may indicate which pattern is being used. This may be signaled using a field in the DCI, for example by reusing the Frequency-Domain Resource Allocation (FDRA) field or parts of it.

[0063] It will be appreciated that although FIG. 3 shows the PDSCH being transmitted within the wake-up signal 330 to different individual UE devices 101-103, the same information may be received and decoded by a group of multiple UE devices.

[0064] Although FIG. 3 shows the wake-up signal 330 spread across four consecutive PRBs in frequency, it may also be transmitted on only a single PRB, or on any other number of PRBs or subcarriers.

[0065] While the present invention has been described and illustrated by way of one or more specific embodiments, it will be understood by those skilled in the art that the invention is not limited to these embodiments, but rather that many variations and modifications are possible within the scope of the appended claims.

Claims

1. 1. A method of operating a wireless system, the method comprising: transmitting an Orthogonal Frequency-Division Multiple-Access (OFDMA) wireless signal, the wireless signal includes information digitally modulated as one or more OFDMA symbols onto one or more subcarriers in a first set of one or more symbol periods and is time interleaved with the first set of one or more symbol periods within a second set of one or more symbol periods, one or more of the subcarriers being unmodulated to provide a predetermined time sequence pattern of modulated and unmodulated symbol periods across the one or more subcarriers; sending configuration information to a first wireless device indicating that some or all of the one or more symbol periods are allocated to the first wireless device on the one or more subcarriers; receiving the wireless signal at the first wireless device of the wireless system, demodulating and using information from one or more modulation symbol periods of the predetermined time sequence pattern, by the first wireless device; receiving the wireless signal at a second wireless device of the wireless system, detecting, by the second radio device, the predetermined time sequence pattern of modulated symbol periods and non-modulated symbol periods in the received radio signal; and generating, in response to detecting the predetermined time sequence pattern in the received wireless signal, a wake-up electrical signal by the second wireless device to activate a wireless module of the second wireless device. The method comprising:

2. The method comprises: a step of detecting the predetermined time series pattern by the second wireless device; determining a time series of energy values, each of the energy values ​​indicative of the energy of a wireless signal received by the second wireless device at a respective time; determining a correlation value by cross-correlating the time series of energy values ​​with data representative of the predetermined time series pattern; and determining whether the correlation value satisfies a wake-up condition.

3. said radio signals being transmitted by a base station of a cellular telecommunications system; 3. The method according to claim 1 or 2, characterized in that

4. The predetermined time sequence pattern includes a plurality of modulated symbol periods and a plurality of non-modulated symbol periods. The method according to any one of claims 1 to 3, characterized in that

5. the one or more subcarriers are a plurality of subcarriers, and for at least one symbol period of the first set of symbol periods, at least two of the plurality of subcarriers encode different symbols. The method according to any one of claims 1 to 4, characterized in that

6. The one or more subcarriers are a plurality of consecutive subcarriers. The method according to any one of claims 1 to 5, characterized in that

7. The configuration information transmitted to the first wireless device includes: only a portion of the first set of one or more symbol periods on the one or more subcarriers being assigned to the first wireless device; The method according to any one of claims 1 to 6, characterized in that

8. and a further wireless device for receiving the wireless signal and demodulating and using information from one or more of the first symbol periods. The method according to any one of claims 1 to 7, characterized in that

9. transmitting configuration information to the further wireless device, The configuration information transmitted to the first wireless device and the configuration information transmitted to the further wireless device specify respective frequency-time resource units within which each wireless device needs to decode information. The method according to claim 8, characterized in that

10. the configuration information transmitted to the first wireless device assigns one or more first subsets of the first set of the plurality of symbol periods on the one or more subcarriers to the first wireless device, and the configuration information transmitted to the further wireless device assigns one or more second subsets of the first set of the plurality of symbol periods on the one or more subcarriers to the further wireless device, the second subset being different from the first subset. The method according to claim 9, characterized in that

11. the further wireless device demodulates and uses information on the one or more subcarriers from a different one or more symbol periods of the first set of symbol periods into one or more symbol periods of the first set of symbol periods from which the first wireless device demodulates and uses information. The method according to any one of claims 8 to 10, characterized in that

12. the wireless signal including no power or negligibly small power in each of the one or more subcarriers in each of the second set of one or more symbol periods. The method according to any one of claims 1 to 11, characterized in that

13. symbol periods of the second set of one or more symbol periods having respective time positions relative to a first instance of resource unit allocation control information within the wireless signal; The method includes the step of transmitting configuration information to the first radio device indicating that a further set of symbol periods having equal time positions relative to a second instance of resource unit allocation control information are allocated to the first radio device on the one or more subcarriers for transmitting information to the first radio device. Further comprising The method according to any one of claims 1 to 12, characterized in that

14. A wireless system including a base station, a first wireless device, and a second wireless device, the base station is configured to transmit an Orthogonal Frequency Division Multiple Access (OFDMA) wireless signal, the wireless signal including information digitally modulated as one or more OFDMA symbols onto one or more subcarriers in a first set of one or more symbol periods, and sending a predetermined time sequence pattern of modulated and unmodulated symbol periods across the one or more subcarriers in a second set of one or more symbol periods time interleaved with the first set of one or more symbol periods, one or more of the subcarriers being unmodulated; The first wireless device receives the wireless signal and demodulates and uses information from one or more symbol periods in the first set of symbol periods; and the second radio device is configured to receive the radio signal, detect the predetermined time sequence pattern of modulated and unmodulated symbol periods in the received radio signal, and generate a wake-up electrical signal in response to detecting the predetermined time sequence pattern in the received radio signal to activate a radio module of the second radio device. A wireless system comprising:

15. 1. A radio device for use in a radio system, comprising: The wireless device includes a wireless module and a wake-up unit; the wireless module has a wake state and a sleep state; The wireless device includes: receiving a plurality of Orthogonal Frequency Division Multiple Access (OFDMA) wireless signals, each wireless signal comprising information digitally modulated as one or more OFDMA symbols onto one or more subcarriers in a first set of one or more symbol periods, and one or more of the subcarriers remaining unmodulated in a second set of one or more symbol periods interleaved in time with the first set of one or more symbol periods, the second set of one or more symbol periods comprising a predetermined time sequence pattern of modulated and unmodulated symbol periods across the one or more subcarriers; receiving a first of the wireless signals when the wireless module is in the wake state, and using the wireless module to demodulate and use information from one or more of the first set of symbol periods of the first wireless signal; receiving a second of the radio signals when the radio module is in the sleep state, detecting, using the wake-up unit, the predetermined time sequence pattern of modulated and unmodulated symbol periods in the second radio signal, and in response to detecting the predetermined time sequence pattern in the second radio signal, transmitting a wake-up electrical signal from the wake-up unit to the radio module to cause the radio module to enter the wake state.

1. A wireless device comprising:

16. detecting the predetermined time sequence pattern of modulation symbol periods and demodulation symbol periods; determining a time series of energy values, each energy value representing the energy of the wireless signal as received by the second device at a respective time; cross-correlating the time series of energy values ​​with data representative of the predetermined time series pattern to determine a correlation value; and determining whether the correlation value satisfies a wake-up condition, What it is configured to do 16. The wireless device of claim 15.

17. the wake-up unit comprises an envelope detector configured to determine a time series of energy values ​​by sampling received energy on the one or more subcarriers; 17. A radio device according to claim 15 or 16, characterized in that

18. the envelope detector is configured to sample received wireless energy at least once every symbol period for the first and second sets of symbol periods.

20. The wireless device of claim 17,

19. the wake-up unit comprises a correlator configured to cross-correlate the time series of energy values ​​with data representing the predetermined time series pattern, thereby determining a correlation value, and the wake-up unit is configured to determine whether the correlation value satisfies a wake-up condition. A radio device according to any one of claims 16 to 18, characterized in that

20. the wake-up unit comprises a memory for storing data representative of the predetermined time sequence pattern, and the wireless device is configured to receive the data representative of the predetermined time sequence pattern in a wireless signal decoded by the wireless module. A radio device according to any one of claims 15 to 19, characterized in that

21. The wireless module is provided by a first semiconductor chip, and the wake-up unit is separate from the first semiconductor chip. A radio device according to any one of claims 15 to 20, characterized in that

22. The radio module includes logic for decoding information from a received radio signal using a Fast Fourier Transformation (FFT).

22. The wireless device according to any one of claims 15 to 21.

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