Methods and apparatuses for on-off-keying waveform transmission and reception

Abstract

A method (500) performed by a wireless device (1000) is disclosed. The method comprises receiving (501 ) a signal based on Orthogonal Frequency Division Multiplexing, OFDM. M ≥ 1 bits are modulated onto an OFDM symbol of the signal by at least the following steps: a first Q-length real-valued or complexvalued sequence or vector is determined using the M bits, where Q = ML and L ≥ 1, and L is an integer number; a second sequence or vector of length D ≥ 1 is determined using at least the first Q -length sequence or vector and a discrete Fourier-based transform; and a mapping of one or more entries to C ≥ 1 resource elements or subcarriers in a frequency domain of the OFDM symbol is performed. The one or more entries are entries of the second sequence or vector, or based on an element-wise-multiplication of entries of the second sequence or vector with a D-length real-valued or complex-valued third vector.

Description

[0001] METHODS AND APPARATUSES FOR ON-OFF-KEYING WAVEFORM TRANSMISSION AND RECEPTION

[0002] TECHNICAL FIELD

[0003] The present invention relates to the field of communication technologies, and to methods and apparatuses for generation, transmission, reception and handling of On-Off-Keying (OOK) waveforms.

[0004] BACKGROUND

[0005] The third-generation partnership project (3GPP) provides for the fifth generation (5G) and will provide for the sixth generation (6G) the complete system specification of the network architecture, which includes the radio access network (RAN), core transport network (CN) and service capabilities. The radio access technology (RAT) in 5G (and 6G) mobile communications systems provides (or will provide) a higher level of performance and flexibility than the previous generations of mobile communications systems. 5G mobile communications have been driven by the need to provide ubiquitous connectivity for applications as diverse automotive communication, remote control with feedback, video downloads, as well as data applications for Internet-of-Things (IoT) devices, machine type communication (MTC) devices, etc. The 5G communication technology brings several main benefits, such as higher speed, lower latency and increased connectivity. This trend will be continued in 6G, and in addition, new technologies such as integrated communication and sensing will possibly be introduced. Radio sensing, as a part of the integrated communication and sensing, can be used by a wireless device or a network node in the communication network to analyze reflections and scattering of transmitted signals to yield knowledge of the physical surroundings. The information of physical surroundings can be used, for example, to enhance resource and beam management in communications systems and hence system performance.

[0006] In IoT scenarios, there is significant interest in improving device form-factor and power consumption considerably to cater to short-range and high-density use-cases. Energyharvesting and backscattering technologies are significant drivers in this regard; the use of cheaper and passive circuitry in such devices make them light, and deployable in a more massive or dense manner than traditional battery-powered IoT devices. Tosupport such devices in existing standards such as the 5G New Radio (NR) standard or the future 6G standard, further improvements to waveform design via Orthogonal Frequency Division Multiplexing (OFDM) are needed to co-exist with other deployments or use-cases using the standard.

[0007] SUMMARY

[0008] In this disclosure, methods for waveform design for reception at wireless devices with low power consumption and processing capabilities are presented. In addition, procedures for feedback of device errors / im perfections during reception are also provided. For low-power devices, it may not always be possible to correct, calibrate or equalize errors with regards to timing or channel distortions completely at the device side. Therefore, with possible feedback of device errors or channel conditions, modifications to the waveform can be performed by a network node with said feedback, thereby improving the reception conditions at the device-side.

[0009] It is an objective of the embodiments herein to provide methods, wireless devices and network nodes configured for generation, transmission, reception and handling of On-Off-Keying (OOK) waveforms.

[0010] According to an aspect of some embodiments herein, there is disclosed a method performed by a wireless device. The method comprises receiving a signal based on Orthogonal Frequency Division Multiplexing, OFDM, wherein M > 1 bits are modulated onto an OFDM symbol of the signal by at least the following steps:

[0011] - a first Q-length real-valued or complex-valued sequence or vector is determined using the M bits, where Q = ML and L > 1, and L is an integer number;

[0012] - a second sequence or vector of length D > 1 is determined using at least the first Q-length sequence or vector and a discrete Fourier-based transform; and

[0013] - a mapping of one or more entries to C > 1 resource elements or subcarriers in a frequency domain of the OFDM symbol is performed, wherein the one or more entries are

[0014] o entries of the second sequence or vector, or

[0015] o based on an element-wise-multiplication of entries of the second sequence or vector with a D-length real-valued or complex-valued third vector.

[0016] According to an aspect of some embodiments herein, there is disclosed a method performed by a wireless device. The method comprises:- receiving a signal based on an on-off-keying, OOK, pulse waveform from a network node, wherein the signal comprises one or more OOK pulses;

[0017] - determining from the signal a timing offset value or information related to a timing offset value, wherein the timing offset value or information related to the timing offset value is based on at least a difference between a time instant at which the wireless device detects a rising / falling edge of an OOK pulse of the one or more OOK pulses and a reference timing value; and

[0018] - reporting the timing offset value or information related to the timing offset value to a network node.

[0019] According to an aspect of some embodiments herein, there is disclosed a method performed by a wireless device. The method comprises:

[0020] - receiving a signal based on an on-off-keying, OOK, pulse waveform from a network node, wherein the signal comprises one or more OOK pulses;

[0021] - determining from the signal a spreading duration or information related to a spreading duration, wherein the spreading duration or information related to a spreading duration is based on a time difference between a time duration of one or more received or detected OOK pulses and a time duration of one or more reference OOK pulses; and

[0022] - reporting the spreading duration or information related to the spreading duration to a network node.

[0023] According to an aspect of some embodiments herein, there is disclosed a method performed by a network node for generating a signal based on Orthogonal Frequency Division Multiplexing, OFDM, wherein M > 1 bits are modulated onto an OFDM symbol. The method comprises:

[0024] - determining a first Q-length real-valued or complex-valued sequence or vector using the M bits, where Q = ML and L > 1, and L is an integer number;

[0025] - determining a second sequence or vector of length D > 1 using at least the first Q- length sequence or vector and a discrete Fourier-based transform;

[0026] - performing a mapping of one or more symbols or entries to C > 1 resource elements or subcarriers in the frequency domain of the OFDM symbol, wherein the one or more entries are

[0027] o entries of the second sequence or vector, oro based on an element-wise-multiplication of entries of the second sequence or vector with a D-length real-valued or complex-valued third vector; and - transmitting the signal to a wireless device.

[0028] According to another aspect of some embodiments herein, there is also provided a wireless device (e.g., a UE or an IoT device) comprising a processor and a memory containing instructions executable by the processor, whereby said wireless device is operative or configured to perform any one of the embodiments presented in the detailed description related to the actions performed by the wireless device.

[0029] According to yet another aspect of embodiments herein, there is provided a network node comprising a processor and a memory containing instructions executable by the processor, whereby said network node is operative or configured to perform any one of the embodiments presented in the detailed description related to the actions performed by the network node.

[0030] There is also provided a computer program comprising instructions which when executed on at least one processor of the wireless device (e.g., a UE or an IoT device), cause the at least said one processor to carry out the actions or method steps presented herein.

[0031] There is also provided a computer program comprising instructions which when executed on at least one processor of the network node, cause the at least said one processor to carry out the method steps presented herein.

[0032] A carrier is also provided containing the computer program, wherein the carrier is one of a computer readable storage medium, an electronic signal, optical signal, or a radio signal.

[0033] An advantage of the embodiments herein is to provide waveform designs for wireless devices with low power consumption and processing capabilities. In addition, improved and simplified procedures for feedback of device errors / imperfections are also provided.

[0034] Additional advantages of the embodiments herein are provided in the detailed description of this disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Embodiments of the present invention are now described in further detail with reference to the accompanying drawings, in which:

[0036] Fig. 1 shows a schematic representation of a wireless communications network, wherein embodiments herein may be applied;

[0037] Fig. 2 presents four distinct topologies for a low-power Ambient Internet of Things (IoT) communication system according to some embodiments herein;

[0038] Fig. 3 illustrates a first deployment scenario for IoT devices (which may be Ambient IoT) according to some embodiments herein;

[0039] Fig. 4 illustrates a second deployment scenario for IoT devices (which may be Ambient IoT) according to some embodiments herein;

[0040] Fig. 5 illustrates a flowchart of a method performed by a wireless device (such as a UE or an IoT device) according to some embodiments herein;

[0041] Fig. 6 illustrates a flowchart of a method performed by a network node (such as a gNB) according to some embodiments herein;

[0042] Fig. 7 is a block diagram depicting a wireless device (such as a UE or an IoT device) according to exemplary embodiments herein;

[0043] Fig. 8 is a block diagram depicting a network node (such as a gNB) according to exemplary embodiments herein; and

[0044] Fig. 9 illustrates the individual blocks for the waveform generation.

[0045] DETAILED DESCRIPTION

[0046] In the present disclosure, methods and procedures for the generation of On-Off-Keying waveforms using OFDM is provided. In addition, methods and procedures for feedback or reporting of information to tailor waveform generation at the transmitter side according to the wireless device or loT device or user’s receiving conditions are provided.

[0047] Figure 1 illustrates a simplified schematic view of an example of a wireless communications network 100 including a core network (CN) 110 and a radio access network (RAN) 120. The RAN 120 is shown including a plurality of network nodes, which in 5G are called gNBs. Three network nodes are depicted as gNB1, gNB2 andgNB3. Each gNB serves an area called a coverage area or a cell. Figure 1 illustrates 3 cells 121, 122 and 123, each served by its own gNB, gNB1, gNB2 and gNB3, respectively. It should be mentioned that the network 100 may include any number of cells and gNBs. The term ‘network node’ used herein may be any kind of network node comprised in a network which may further comprise any of base station (BS), radio base station (RBS), base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), g Node B (gNB), evolved Node B (eNB or eNodeB), Node B, multiple transmission point (multi-TRP), 5G access nodes, multistandard radio (MSR) radio node such as MSR BS, multi-cell / multicast coordination entity (MCE), integrated access and backhaul (IAB) node, relay node, donor node controlling relay, radio access point (AP), access point station (AP STA), transmission points, transmission nodes, Remote Radio Unit (RRU), Remote Radio Head (RRH), a core network node (e.g., mobile management entity (MME), self-organizing network (SON) node, a coordinating node, positioning node, MDT node, etc.), an external node (e.g., 3rd party node, a node external to the current network), nodes in distributed antenna system (DAS), a spectrum access system (SAS) node, an element management system (EMS), etc. The network node may also comprise test equipment. The network nodes serve users within a cell. A wireless device (WD) may be a user equipment (UE), non-access-point station (non-AP STA), a mobile terminal, a wireless terminal, a mobile station, an IoT device, a machine type communication (MTC) device, etc. loT devices may include wireless sensors, software, actuators, and computer devices. The IoT devices can be imbedded into mobile devices, motor vehicles, industrial equipment, environmental sensors, medical devices, aerial vehicles and more, as well as network connectivity that enables these devices to collect and exchange data across an existing network infrastructure. In some embodiments, the non-limiting terms wireless device (WD), non-access-point station (non-AP STA) or a user equipment (UE) are used interchangeably.

[0048] Referring to Figure 1, each cell as shown may include UEs and loT devices. Network node gNB1 in cell 121 serves UE1 121 A, UE2 121 B and loT device 121 C. Similarly, network node gNB2 in cell 122 serves UE3 122A, UE4 122B and IoT device 122C, and network node gNB3 in cell 123 serves UE5 123A, UE6 123B and IoT device 123C. The wireless communications network 100 may include any number of UEs and loT devices or any other types of devices. The wireless devices communicate with the serving gNB(s) in the uplink and the gNB(s) communicate with the wireless devices inthe downlink. The respective network nodes gNB1 to gNB3 may be connected to the CN 110, e.g., via the S1 interface, via respective backhaul links 111, 121 D, 122D, 123D, which are schematically depicted in Figure 1 by the arrows pointing to “core”. The core network 110 may be connected to one or more external networks, such as the Internet. The gNBs may be connected to each other via the S1 interface or the X2 interface or the XN interface in 5G, via respective interface links 121 E, 122E and 123E, which are depicted in the figure by the arrows pointing to gNBs.

[0049] For data transmission, a physical resource grid may be used. The physical resource grid may comprise a set of resource elements (REs) to which various physical channels and physical signals are mapped. For example, the physical channels may include the physical downlink, uplink and / or sidelink (SL) shared channels (PDSCH, PUSCH, PSSCH) carrying user specific data, also referred to as downlink, uplink or sidelink payload data, the physical broadcast channel (PBCH) carrying for example a master information block (MIB) and a system information block (SIB), the physical downlink, uplink and / or sidelink control channels (PDCCH, PUCCH, PSCCH) carrying for example the downlink control information (DCI), the uplink control information (UCI) or the sidelink control information (SCI). For the uplink, the physical channels may further include the physical random-access channel (PRACH or RACH) used by UEs for accessing the network once a UE is synchronized and obtains the MIB and SIB. The physical signals may comprise reference signals (RS), synchronization signals (SSs) and the like. The resource grid may comprise a frame or a radio frame having a certain duration, like 10 milliseconds, in the time domain and having a given bandwidth in the frequency domain. The radio frame may have a certain number of subframes of a predefined length, e.g., 2 subframes with a length of 1 millisecond. Each subframe may include one or more slots of a number of orthogonal frequency-division multiplexing (OFDM) symbols depending on the cyclic prefix (CP) length. In 5G, each slot consists of 14 OFDM symbols or 12 OFDM symbols based on normal CP and extended CP respectively. A frame may also consist of a smaller number of OFDM symbols, e.g., when utilizing shortened transmission time intervals (TTIs) or a mini-slot / non-slot-based frame structure comprising just a few OFDM symbols. Slot aggregation is supported in 5G NR and hence data transmission can be scheduled to span one or multiple slots. Slot format indication informs a UE whether an OFDM symbol is downlink, uplink orflexible / special.The wireless communications network may be any single-tone or multicarrier system using frequency-division multiplexing, like the orthogonal frequency-division multiplexing (OFDM) system, the orthogonal frequency-division multiple access (OFDMA) system, or any other Discrete Fourier Transform (DFT) based signal with or without CP, e.g., DFT-spread OFDM (DFT-s-OFDM). Other waveforms, like non-orthogonal waveforms for multiple access, e.g., filter-bank multicarrier (FBMC), generalized frequency division multiplexing (GFDM) or universal filtered multi carrier (UFMC), may also be used. The wireless communication system may operate, e.g., in accordance with the LTE standard, the 5G or NR (New Radio) standard, IEEE (Institute of Electrical and Electronics Engineers) 802.11 standards (e.g., 802.11 ax, 802.11 be, etc.), the future 6G standard, or any other standard using any of the aforementioned waveforms.

[0050] The wireless communications network depicted in Figure 1 may be a heterogeneous network having two distinct overlaid networks, a network of macro cells with each macro cell including a macro base station, like base station gNB1 to gNB3, and a network of small cell base stations (not shown in Figure 1), like micro-, nano-, femto-or pico-base stations. In addition to the above-described wireless network, nonterrestrial wireless communication networks also exist including spaceborne transceivers, like satellites, and / or airborne transceivers, like unmanned aircraft systems. The non-terrestrial wireless communication network or system may operate in a similar way as the terrestrial system described above with reference to Figure 1, for example in accordance with the LTE-advanced pro standard or the 5G standard, or 6G standard.

[0051] In the wireless communications network such as the one depicted schematically in Figure 1, multi-antenna techniques may be used, e.g., in accordance with LTE, NR, any IEEE standards or any other communication system, to improve user data rates, link reliability, cell coverage and network capacity. To support multi-stream or multilayertransmissions, linear precoding is used in the physical layer of the communication system. Linear precoding is performed by a precoder matrix which maps layers of data to antenna ports. The precoding may be seen as a generalization of beamforming, which is a technique to spatially direct or focus a data transmission towards an intended receiver. The precoder matrix to be used at the gNB to map the data to the transmit antenna ports is decided using channel state information (CSI).In the wireless communications network described above, operating via the LTE, New Radio (5G) or any IEEE standard, various physical channels are defined for the communication of data payload and control information. In addition, various reference signals are also designed for purposes such as link adaptation and management, demodulation, frame synchronization, cell search, phase tracking, among others. A gNodeB (or gNB or base station) transmits to one or more users in the downlink. A wireless device such as a user equipment (UE) transmits to one or more base stations in the uplink. In the sidelink, two or more UEs may be involved in communication. The data payload is transmitted via the physical downlink shared channel (PDSCH) in the downlink (DL), via the physical uplink shared channel (PUSCH) in the uplink (UL) and via the physical sidelink shared channel (PSSCH) in the sidelink (SL) of a wireless network. The control information is typically transmitted via the physical downlink control channel (PDCCH) in the downlink (DL), via the physical uplink control channel (PUCCH) in the uplink (UL) and via the physical sidelink control channel (PSCCH) in the sidelink (SL), of a wireless network. The physical broadcast channel (PBCH) is transmitted along with the synchronization signals (SS) in the downlink as a SS / PBCH block to aid in cell search and downlink synchronization. A SS / PBCH block may be interchangeably referred to as a SS block (SSB). The physical sidelink broadcast channel (PSBCH) in the sidelink is similar in structure and functionality to the PBCH. The physical random-access channel (PRACH) in the uplink is characterized by the PRACH preamble and is used for uplink synchronization. The PDSCH, PDCCH, PBCH, PUSCH, PUCCH, PSSCH, PSCCH and PSBCH are provided with DeModulation Reference Signals (DMRS) for coherent demodulation of the channel. The number of DMRS antenna ports during a given instance of transmission of the channel is equal to the number of layers transmitted. A layer of the transmission of a channel may be referred to using the DMRS port associated with it.

[0052] 5G New Radio (NR) may support an operation in the unlicensed spectrum so that a multi-band operation may include frequency bands in the unlicensed spectrum bands. This may be as NR-based access to unlicensed spectrum, NR-U, and the frequency bands may be referred to as subbands. The unlicensed spectrum may include bands with a potential IEEE 802.11 coexistence, such as the 5GHz and the 6GHz bands. NR-U may support bandwidths that are an integer multiple of 20 MHz, for example due to regulatory requirements. The splitting into the subbands is performed so as to minimize interference with coexisting systems, like IEEE 802.11 systems, which may operate inone or more of the same bands with the same nominal bandwidth channels, like 20 MHz channels. Other examples, of coexisting systems may use subbands having subband sizes and nominal frequencies different from the above-described IEEE 802.11 systems. For example, the unlicensed spectrum may include the 5GHz band, the 6GHz band, the 24GHz band or the 60GHz band. Examples of such unlicensed bands include the industrial, scientific and medical, ISM, radio bands reserved internationally for the use of radio frequency energy for industrial, scientific and medical purposes other than telecommunications.

[0053] During an operation using unlicensed subbands, Listen-before-talk, LBT, is to be performed separately per subband. This may lead to a situation in which one or more of the subbands are busy or occupied due to an interference, for example, from other communication systems coexisting on the same band, like other public land mobile networks, PLMNs or systems operating in accordance with the IEEE 802.11 specification. In such a situation, the transmitter, either the transmitting gNB or the transmitting UE, is only allowed to transmit on the subbands which are detected to be not busy, also referred to as subbands being free or non-occupied, as is determined by the LBT algorithm. For example, for a transmission spanning more than 20MHz in the 5GHz operational unlicensed band, the transmitter, like the gNB or the UE, performs Listen-Before-Talk, LBT, separately on each subband. Once the LBT results are available for each subband, the devices, for example, the gNB in the downlink, DL, or the UE in the uplink, UL, are allowed to transmit on those subbands which are determined to be free or unoccupied, i.e., to transmit on the won subband(s). No transmission is allowed on the occupied, busy or non-won subbands.

[0054] The term ‘higher layer’ in the following, when used in isolation, denotes any communication layer above the physical layer in the protocol stack. The physical channels described above are associated with the ‘PHY’ layer or the physical layer in the protocol stack. Some of the layers ‘above’ the physical layer in the protocol stack are the medium access control (MAC) and radio resource control (RRC). The wireless device may also exchange messages or information across layers in the protocol stack. The wireless device typically receives configuration, indication, information or messages via higher layers (e.g., MAC or RRC) from a network node or another wireless device. The configuration, indication, information or message(s) may comprise information regarding parameter(s) / value(s) or signalling involved incommunication between the wireless device and the network or the other wireless device. In some cases, the configuration, indication, information and / or messages via the MAC layer may be provided to the wireless device using MAC-Control Element (MAC-CE) messages.

[0055] The terms ‘serving cell’ and ‘carrier component (CC)’ may be used interchangeably in the present disclosure as a serving cell configured for a wireless device (such as a UE) and is usually a separate physical carrier with a certain carrier frequency. Depending on the frequency of a component carrier / serving cell, the size of the cell and the beamformed reference signals may vary. Each serving cell or component carrier comprises NBWP> 1 bandwidth parts (BWP) which is a set of frequency domain resources. At any given time in a serving cell, the UE may receive physical layer transmissions from a TRP or any other network element in one of the configured BWPs in the DL in the cell and / or may perform transmissions in one of the configured BWPs in the UL in the cell.

[0056] It is to be noted that any mention of an action performed by a network node such as a gNodeB (gNB) may also be performed by any other element of the network and hence any concerned statement shall be read as such.

[0057] Figure 2 presents five distinct topologies for a low-power Ambient Internet of Things (IoT) communication system. An ambient loT device is typically a low-power, and often battery-free device. They are often designed to perform energy harvesting from ambient sources such as RF radiation, vibration, heat, light, etc. In addition, they are also designed to perform radiation backscattering - modulating and reflecting incoming radiation, rather than performing signal generation themselves. Signal generators in a device typically consume a lot of energy and energy-harvesting devices may not always be able to harvest enough energy from ambient sources to support signal generation of their own; batteries may have to be included in the device to perform signal generation. Therefore, backscattering incoming radiation is one of the ways to support energy harvesting devices.

[0058] In Topology 1, the base station (BS) transmits data to an loT device, with the transmitting BS potentially different from the receiving BS. Topology 2 introduces an intermediate node between the BS and the Ambient loT device. This intermediate node can serve various functions such as a relay, Integrated Access and Backhaul (IAB) node, User Equipment (UE), or repeater, facilitating the transfer of loT data andsignalling. Topologies 3 and 4 describe scenarios where the Ambient loT device communicates with an assisting node. In topology 3, an assisting node acts as an intermediate node for downlink communication - transmissions from the base station to the ambient loT device, while the transmissions from the ambient loT device to the base station are performed directly without intermediates. In topology 4, the assisting node acts as an intermediate in the uplink -transmissions from the ambient loT device to the base station, but the downlink transmissions from the base station to the ambient loT device are direct. The assisting node in these two topologies may also be a relay, IAB node, UE, or repeater. Finally, Topology 5 illustrates a bidirectional communication where the loT device interacts directly with a User Equipment (UE). This topology emphasizes the direct link between the loT device and the UE for data exchange. These topologies highlight the various methods through which loT devices can connect and communicate within a network, showcasing the flexibility and complexity of loT system designs.

[0059] Figures 3 and 4 illustrate two deployment scenarios for loT devices (which may be ambient loT devices), each scenario employing different topologies. In both scenarios, the following entities exist:

[0060] Device (D) refers to the loT device itself, which is responsible for transmitting data, typically using energy harvesting or backscattering. The loT device may, in certain scenarios, also be referred to as a Tag.

[0061] Reader (R) is defined as the device that transmits and / or receives transmissions to / from the loT device. From the various topologies discussed above, it can be understood that a reader can be a network node, base station or another wireless device (e.g., a user equipment).

[0062] Carrier Wave (CW) represents a device transmitting a waveform that is backscattered / reflected by a device with information modulated in the backscattered / reflected radiation.

[0063] It is to be noticed that “CW2D” may indicate the signal communication from a Carrier Wave (CW) to a Device (D). Similarly, “R2D” may indicate the signal communication from a Reader (R) to a Device (D). Other signal communications in Figures 3 and 4 may be interpretated in a similar way, where “2” may indicate a signal direction “to”. A network in such loT scenarios may offer the following services:Inventory is a service provided by the network that facilitates the discovery and acquisition of identifiers for loT devices.

[0064] Command enables the sending of operational instructions to the loT device. Examples of such commands include actions like reading data from the device or writing new information to it.

[0065] In Deployment Scenario 1, both the devices and the base station are typically located indoor. This scenario includes four topologies: Topology A presents a CW device that is co-located with the reader R1 that transmits to the device, but the receiving reader R2 is at a different location. Topology B depicts a CW that is co-located with a reader R that both transmits and receives from the device D. Topology C differs from topology B in the sense that the CW is at a different location from that of the reader R. Topology D does not include a CW, and it is applicable to devices that can generate signals on their own and do not backscatter. In all the topologies, the base station is not explicitly shown in Figure 3 as it is considered to be co-located (in similar vicinity or the same transmission / reception point) with the reader(s) (for e.g., both the readers and the base stations are indoors) and / or the interface between the base station and the reader may not exist in certain cases as the reader itself may serve as the base station.

[0066] In Deployment Scenario 2, the devices and / or the reader are typically indoor while the base station is typically away from them (e.g., outdoor). Topologies A, B and C in this scenario are similar to the Topologies A, C and D, respectively of Deployment Scenario 1 with the base station BS communicating with the reader(s) (R1, R2, R).

[0067] It is to be noted that any mention of an action performed by a network node such as a gNodeB (gNB) may be performed by a reader. Similarly, any mention of an action performed by a wireless device, may be performed by a user equipment, loT device, ambient-loT device, vehicular communication equipment, etc.

[0068] The downlink transmission in a backscattering loT scenario is the transmission from a ‘reader’ to a ‘tag’ or ‘device’. The reader transmits very simple waveforms such on On-Off-keying pulses or lower-order modulated pulses for demodulation at the tag / device which has a low power consumption. When such transmissions are to be performed in a network deployed based on a standardized waveform (e.g., OFDM) and co-exist with other transmissions in the network, then the simple waveforms for the low-power loT downlink shall be accommodated (i.e., multiplexed) within the same waveformstructure with pulse-shaping within said waveform. In the following, methods are proposed for such waveforms that allow for co-existence and shape pulses in the desirable manner for the tag / device to receive and / or demodulate.

[0069] General waveform structure

[0070] In certain embodiments, a wireless device is configured to receive and / or demodulate an On-Off-Keying (OOK) waveform that comprises one or more On-Off-Keying (OOK) pulses, or one or more ‘On’ and / or ‘Off’ pulses, wherein an ‘On’ pulse may be associated with a bit value of T (or ‘0’), and an ‘Off’ pulse may be associated with a bit value of ‘0’ (or ‘1’).

[0071] In this disclosure, a pulse in an OOK waveform or an OOK pulse can be considered as a predetermined, specified or configured duration of the waveform that comprises voltage / power / amplitude level(s) that indicate(s) a bit information. The term ‘OOK pulse’, in general, may denote an ‘On’ pulse or an ‘Off’ pulse.

[0072] In certain embodiments, the duration of either an ‘On’ pulse or an ‘Off’ pulse (i.e., an OOK pulse) at a certain instance or at a certain duration in the waveform or across the whole waveform is called as a chip duration. In certain cases, the chip duration may vary at different instances or at different windows of time in the waveform structure. In this disclosure, the term ‘chip rate’ in the context of a OOK waveform may denote the number of ‘On’ and / or ‘Off’ pulses (i.e., OOK pulses) of the waveform at a certain instance or at a certain duration.

[0073] In the following, methods to generate OOK waveforms using OFDM are presented. A bit-stream of B > 1 bits are to be modulated and transmitted as OOK pulses using the OFDM waveform. For this purpose, the B bits could be split into chunks of M > 1 bits and each of the M-bit(s) chunk could be modulated onto an OFDM symbol. DFT-spread OFDM is used in the methods below for OOK waveform generation.

[0074] In certain embodiments, a method performed by a wireless device comprises receiving a signal based on Orthogonal Frequency Division Multiplexing, OFDM, wherein M > 1 bits are modulated onto an OFDM symbol of the signal by at least the following steps: - a first Q-length real-valued or complex-valued sequence or vector is determined using the M bits, where Q = ML and L > 1, and L is an integer number;- a second sequence or vector of length D > 1 is determined using at least the first Q-length sequence or vector and a discrete Fourier-based transform; and

[0075] - a mapping of one or more entries to C > 1 resource elements or subcarriers in a frequency domain of the OFDM symbol is performed, wherein the one or more entries are

[0076] o entries of the second sequence or vector, or

[0077] o based on an element-wise-multiplication of entries of the second sequence or vector with a D-length real-valued or complex-valued third vector.

[0078] In certain embodiments, it is disclosed a method performed by a network node for generating a signal based on Orthogonal Frequency Division Multiplexing, OFDM, wherein M > 1 bits are modulated onto an OFDM symbol. The method comprises: - determining a first Q-length real-valued or complex-valued sequence or vector using the M bits, where Q = ML and L > 1, and L is an integer number;

[0079] - determining a second sequence or vector of length D > 1 using at least the first Q- length sequence or vector and a discrete Fourier-based transform;

[0080] - performing a mapping of one or more symbols or entries to C > 1 resource elements or subcarriers in the frequency domain of the OFDM symbol, wherein the one or more entries are

[0081] o entries of the second sequence or vector, or

[0082] o based on an element-wise-multiplication of entries of the second sequence or vector with a D-length real-valued or complex-valued third vector; and - transmitting the signal to a wireless device.

[0083] The first sequence or vector described above is labelled in the following as rq. The second sequence or vector described above is labelled in the following as rd.

[0084] The value M denotes the number of chips of the OFDM symbol, i.e., the number of OOK pulses of the OFDM symbol. Therefore, the value M is called the chip rate (or the OOK chip rate) of the OFDM symbol in the following. Since the OFDM symbol has a fixed length, the value M determines how wide an OOK ‘On’ or ‘Off’ pulse is.

[0085] In this disclosure, the i-th entry of a vector x is denoted as x(i). If the vector is of length X, then i is from 0, 1,..., X - 1 or 1, 2,..., X.It is also to be noted that, in this disclosure, an element-wise multiplication of two sequences or vectors x and y, each of length X, to obtain another X-length vector or sequence z, means that the i-th element or entry of sequence or vector z is given by the product of the i-th element of x and the i-th element of y, i.e., z(i) = x(i) • y(i). This operation may also be expressed as z = x ⊙ y. The whole process of generating an OOK waveform using the OFDM waveform generation structure, as described above by the three steps, can be further split into smaller steps as shown in Figure 9 - bit spreading, pre-DFT-spreading pulse shaping and / or sequence sampling, DFT-spreading, post-DFT-spreading pulse shaping and / or sequence sampling, subcarrier mapping and OFDM generation. The individual blocks are described in further detail below.

[0086] Bit-spreading

[0087] In certain embodiments, the computation of a Q-length vector rqusing the M bits to be modulated or mapped to an OFDM symbol, where Q = ML and L > 1, involves at least one of the following steps:

[0088] - An up-sampling of M bits to be mapped to the OFDM symbol by a factor L resulting in a Q-length sequence or vector rq', wherein the first L entries of rq' are associated with the first bit of the M bits, the second L entries of rq' are associated with the second bit of the M bits, and so on,

[0089] - A multiplication of each bit by an L-length real-valued or complex-valued sequence or vector Sj and concatenating the result to obtain a Q-length sequence or vector rq', wherein the first L entries of rq' are associated with the first bit of the M bits, the second L entries of rq' are associated with the second bit of the M bits and so on. In some examples, a bit in a sequence or vector can be from the value zero or one or it can be from the value minus one and plus one.

[0090] In the above step, each bit in the M-bit-sequence to be mapped to an OFDM symbol is spread by an L-length sequence s!, or simply repeated L times. The value of L is called as the spreading (bit-spreading) or up-sampling factor.

[0091] In certain embodiments, the L-length sequence or vector s! is at least one of the following:- a sequence or vector of ones, i.e., a vector with all its entries equal to one, - a sequence or vector of ones and / or zeros, i.e., a sequence or vector wherein any given entry is either a one or a zero,

[0092] - a sequence or vector wherein any given entry is either a zero or a positive real number,

[0093] - a sequence or vector wherein any given entry is a complex exponential of unit magnitude,

[0094] - a sequence or vector wherein any given entry is either a zero or a complex number. In certain embodiments, the L-length sequence or vector sj is a sequence or vector wherein any given entry is either a zero or a complex number with unit magnitude. Pre-DFT-spreading pulse-shaping

[0095] In certain embodiments, the Q-length sequence or vector rqis determined from the Q-length sequence or vector rq' using at least one of the following methods:

[0096] - rq= r'q, or

[0097] - rqis obtained by an element-wise-multiplication of the entries of rqwith the entries of a real-valued or complex-valued Q-length vector sq, i.e., rq= rqO sq.

[0098] In the above step, pulse-shaping of the waveform is performed when multiplying rqwith sq, or no pulse-shaping is performed when rq= rq. In certain embodiments, the Q-length sequence or vector sqis at least one of the following:

[0099] - a sequence or vector of ones, i.e., a sequence or vector with all its entries equal to one,

[0100] - a sequence or vector wherein any given entry is either a zero or a positive real number,

[0101] - a sequence or vector of ones and / or zeros, i.e., a sequence or vector wherein any given entry is either a one or a zero,

[0102] - a sequence or vector wherein any given entry is a complex exponential of unit magnitude,

[0103] - a sequence or vector wherein any given entry is either a zero or a complex number. In certain embodiments, the Q-length sequence or vector sqis a sequence or vector wherein any given entry is either a zero or a complex number with unit magnitude.When a sequence or vector of ones and zeros is inserted, this gives rise to holes or gaps within the on-pulse of the OFDM symbol. In certain cases, a method is proposed to introduce guard intervals within an on-pulse (for e.g., the last few entries of sqare zero and the other entries are non-zero or one), so that the ‘on’ width of on-pulse is shorter than the full chip interval. Such guard-intervals can be inserted for robustness against timing errors or channel multi-path propagation.

[0104] In certain cases, the Q -length sequence or vector sqis a sequence or vector of complex exponentials with linearly increasing or decreasing phases. In some examples, the entries of sqcomprise unit-magnitude complex exponentials.

[0105] In certain cases, the Q-length vector sqis generated using a Zadoff-Chu sequence, Gold-code, M-sequence or Golay-sequence. It is to be noted that the letter ‘M’ in ‘M-sequence’ is not related to the chip rate M mentioned above.

[0106] The use of complex-valued sequences shifts the phases of each subcarrier or resource element of the OFDM signal, so that they superimpose desirably to form square / rectangle-shaped pulses. With phase-ramp and / or phase-randomization based on the spreading sequence length, the type of superposition of adjacent subcarriers and their possible spreading / widening is controlled, thereby determining the ripples and roll-off in the square-pulse.

[0107] Sequence extension or down-sampling, and DFT-spreading

[0108] In certain embodiments, determining the sequence or vector rdusing the sequence or vector rqinvolves at least the computation of a sequence or vector rdwhich is obtained by performing a D -point discrete Fourier-based or discrete inverse Fourier-based transform of

[0109] o the Q-length sequence or vector rq, or

[0110] o a Q'-length sequence or vector rqwherein

[0111] ■ Q' > Q and the sequence or vector rqis obtained by padding or inserting one or more zeros to the sequence or vector rq, or

[0112] ■ Q' Q and the sequence or vector rqis obtained by performing a mapping of entries from the sequence or vector rqto rq,

[0113] o a Q-length sequence or vector rqwherein■ Q > Q and the sequence or vector rqis obtained by padding or inserting one or more zeros to the sequence or vector rq, and then performing an element- wise multiplication of entries of the resulting vector with entries of another Q- length sequence sq, or

[0114] ■ Q Q and the sequence or vector rqis obtained by performing a mapping of entries from the sequence or vector rqto obtain a Q-length sequence or vector rqand then performing an element-wise multiplication of entries of rqwith entries of another Q-length sequence sq, i.e., rq= rqO sq. While the sequence sqmay use phases for ‘coherent’ or ‘desirable’ superposition of subcarriers, the sequence sqmay be used for magnitude-based attenuation or amplification of subcarriers for pulse-shaping.

[0115] In certain cases, the Q'-length or Q-length sequence or vector rqis obtained from the sequence or vector rqvia one of the following methods:

[0116] - ^

[0117]

[0118] q( / (0) =rq(0>i = 0,..., Q - 1, where / (i) denotes a mapping function from the indices of rqto the indices of rq,

[0119] - r

[0120]

[0121] q(i) = rq( / (i)), i = 0,..., Q' - 1 or i = 0,..., Q - 1, where / (i) denotes a mapping function from the indices of rqto the indices of rq.

[0122] In certain cases, the Q'-length or Q-length sequence or vector rqis obtained from the sequence or vector rqas follows: rq(i) = rq(mod(i, Q)), i = 0,

[0123]

[0124] - 1 or i = 0 Q - 1.

[0125] This resource element or subcarrier mapping, extension or zero-padding / insertion before the DFT-spreading may be used to further extend or reduce the frequency domain occupancy of the DFT-spread-subcarriers. On the other hand, without any sequence extension or down-sampling before DFT-spreading and having a DFT-spreading length equal to the sequence length, the information from the sequence is captured in an identical number of samples, without losing information or including additional information. With such a method, post-DFT-spreading extension or downsampling can be carried out to improve the information ‘richness’ or ‘concentration’. In certain cases, D = Q.In certain cases, D = Q 'or D = Q.

[0126] Pulse-shaping after DFT-spreading / Post-DFT-spreading pulse-shaping

[0127] In certain embodiments, the £> -length sequence or vector rdis element-wise-multiplied by a £)-length real-valued or complex-valued sequence or vector sdto obtain a D-length sequence or vector rd, i.e., rd= rd⊙ sd. - In certain embodiments, a C-length sequence or vector rc' is computed using the D-length sequence or vector rdorrd, wherein the computation includes at least one of the following steps: the D entries of rdor rdare mapped to C entries of sequence or vector rc', one-to-one (in this case C = D),

[0128] - the C entries of sequence or vector rc' are obtained by padding or inserting one or more zeros to the sequence or vector rdor rd(in this case, C > D), or

[0129] - the C entries of sequence or vector rc' are obtained by performing a mapping of entries from the sequence or vector rdor rd(in this case, C may or may not be equal to D).

[0130] In certain embodiments, only a subset of the entries of the sequence or vector rdor rdare mapped to the entries of sequence or vector rc'. In this case C < D.

[0131] In certain embodiments, at least one of the entries of sequence or the vector rdor rdis mapped to two or more entries of the sequence or vector rc'. In this case C may or may not be equal to D. In certain instances, C > D.

[0132] In certain embodiments, the i-the entry of the sequence or vector rdor rdis mapped to the index g(i) = mod(i, C), i = 0,..., D - 1 in the sequence or vector rc'.

[0133] In certain embodiments, a C-length sequence or vector rcis determined from the C-length sequence or vector rc' using at least one of the following methods:

[0134] -rc =rc>or

[0135] - rcis obtained by an element-wise-multiplication of the entries of rc' with the entries of a real-valued or complex-valued C-length vector sc, i.e., rc= rc' O sc.In the above method, the sequence scis used to perform a last step pulse-shaping in the frequency domain before converting to the time domain. This pulse-shaping could be used to control out-of-band emissions, for example.

[0136] In any of the pulse-shaping steps used in any of the above methods, the entries of the pulse-shaping vector or sequence may be obtained from standard windows such as raised-cosine, Hamming, Hann, Kalman, Blackman, etc. or from optimized coefficients computed via least-squares, convex optimization techniques, etc.

[0137] In certain embodiments, the entries of the C-length sequence or vector rcare mapped to C resource elements or subcarriers in the frequency domain of an OFDM symbol. In certain embodiments, at least a N-point inverse discrete Fourier transform (IDFT) or a discrete Fourier transform (DFT) is performed on the C-length vector rc, wherein N ≥ C, to obtain a N-length sequence or vector rt.

[0138] In certain cases, the mapping is performed to C resource elements or subcarriers from N > C available resource elements or subcarriers.

[0139] In certain embodiments, at least a N-point IDFT or DFT is performed on a N-length vector that represents or denotes said N resource elements or subcarriers to obtain a N-length sequence or vector rt.

[0140] In certain cases, one or more complex exponential multiplications may be applied on one or more resource elements or subcarriers before the IDFT or DFT operation. In certain cases, one or more complex exponential multiplications may be applied on one or more entries of the vector or sequence that is obtained after the IDFT or DFT operation.

[0141] The IDFT or DFT operation in an OFDM symbol converts the frequency domain representation of the symbol (the subcarrier or resource element mapping of an OFDM symbol) to the time domain, i.e., the N-length sequence or vector represents the OFDM symbol in the time-domain.

[0142] In certain embodiments, the C resource elements or subcarriers are present in contiguous physical resource blocks (PRBs) or resource blocks (RBs).In certain embodiments, there is no restriction on the physical resource blocks the C resource elements or subcarriers are present, i.e., the C resource elements or subcarriers are present in contiguous or non-contiguous physical resource blocks. In certain embodiments, a prefix of P entries is appended to the time-domain sequence, vector or signal corresponding to an OFDM symbol, wherein the prefix comprises the last P entries of said time-domain sequence, vector or signal. This is called the cyclic prefix, which is used to combat inter-OFDM-symbol interference that may occur due to channel delay spread.

[0143] In certain embodiments, no prefix is appended to the time-domain sequence, vector or signal corresponding to an OFDM symbol, i.e., P = 0 entries are appended to the timedomain sequence, vector or signal corresponding to an OFDM symbol. For example, such a cyclic-prefix-less symbol may be generated during the transmission of the initial signal to the wireless device.

[0144] Relationship between various waveform parameters

[0145] Based on the waveform structure described above, various tasks such as pulseshaping, bandwidth extension, guard-width insertion, subcarrier allocation, DFT-spreading, etc. can be split into individual processing blocks and can be tailored according to device implementations. The blocks can be flexibly designed for a desired waveform structure or device and link restriction. In the following, some possible / reasonable restrictions of the waveform structure are discussed.

[0146] In certain embodiments, a minimum number of PRBs Z„inis allocated for a given value of M.

[0147] In certain embodiments, the minimum value of L used for a given value of M, L^in, is at least one of the following:

[0148] -minMRB

[0149] / min _ZM,jVsc

[0150] >

[0151] -minMRB

[0152] rmin >ZM,jVsc

[0153] M

[0154] Z-min

[0155] ,WRB1

[0156] M

[0157] Lrmin >jVsc

[0158] M —

[0159]

[0160] Mwherein denotes the number of subcarriers in a physical resource block of the radio frame.

[0161] In certain embodiments, the allowable values of L for a given value of M are L$n■ i with i = 1,2,...

[0162] In certain examples, at least one of the following minimum applicable value of L is used:

[0163] - For M = 1, the L'"'n= 12

[0164] - For M = 2, the

[0165]

[0166] = 6

[0167] - For M = 4, the Ln^n= 3

[0168] - For M = 6, the

[0169]

[0170] = 2

[0171] - For M = 8, the Ln^n= 3

[0172] - For M = 12, the L'"'n= 2

[0173] - For M = 16, the Ln^n= 1 or 2

[0174] - For M = 24, the Ln^n= 1 or 2

[0175] - For M = 32, the L'"'n= 1 or 2

[0176] In certain examples, the applicable values of L for a given value of M may be as provided in the table below. The value i = 1, 2,...

[0177] M 1 2 4 6 8 12 16 24 32 L 12i 6i 3i 2i 3i 2i i or 2i i or 2i i or 2i

[0178]

[0179] In the above methods, the value of L is set that the bit-spreading results in filling up an integer number of PRBs, or the number of resource elements across the allocated PRBs is at least higher than the value of Q = ML. This would mean that there is no loss during bit-spreading leading to the pre-DFT-spread pulse-shaping.

[0180] In certain examples, the value of Q is even.

[0181] In the following, further restrictions regarding various values in the waveform generation procedure are provided to achieve ‘desirable’ results.

[0182] In certain embodiments, the value of Q = ML is greater than or equal to the value of C. In certain embodiments, the value of D is greater than or equal to the value of C.With the above conditions, at least as many subcarriers or resource elements are allocated as the number of symbols or elements generated by the bit-sequence spreading and / or DFT-spreading, thereby completely determining the full OOK-pulse information with the DFT-spreading, while leaving the sequence repetition or extension process after the DFT-spreading to take care of further pulse-shaping.

[0183] The design question on the number of subcarriers that can be used in the frequency domain for pulse-shaping and transmission, heavily depends on the wireless device conditions regarding reception circuitry and processing capabilities.

[0184] In certain embodiments, the maximum value of C is expressed in terms of the number of physical resource blocks. It is to be noted that a physical resource block, in certain standards such as 5G-NR or LTE, comprises 12 subcarriers or resource elements. In certain embodiments, the wireless device does not expect to receive a transmission occupying more than

[0185]

[0186] resource blocks or physical resource blocks. That is,

[0187]

[0188] denotes the maximum number of resource blocks that can be used for the transmission. In some examples,

[0189]

[0190] takes a value greater than or equal to 4. In some examples,

[0191]

[0192] takes a value less than or equal to 10.

[0193] In certain embodiments, the value of / V^ is a value determined by a parameter or index that indicates the type of the wireless device.

[0194] In certain embodiments, the maximum value

[0195]

[0196] of is predetermined or fixed in the standard specifications.

[0197] A special case is presented as follows. Currently, a plethora of low-power wireless devices are available in markets that employ a sampling frequency of around 1.92 MHz, which means that the maximum usable bandwidth is 960 kHz (Nyquist frequency). With a subcarrier spacing of 15 kHz, at most 10.667 physical resource blocks can be allocated to occupy the given maximum bandwidth, while employing a ‘perfect’ all-pass filter. But, considering filter roll-off properties and hardware deficiencies of such low-power devices, only a maximum of 10 physical resource blocks are allocated given the conditions in various standards for allocation in terms of integer number of physical resource blocks, even for the devices with the ‘best’ low-pass filter implementations. Therefore, depending on the filter implementations in a wireless device, the maximum number of usable physical resource blocks for transmissions to the device may be set.Metric-based waveform generation

[0198] It is to be noted that, while the OFDM waveform structure is used for the generation of the OOK signal, the receiver does not need all the information regarding the waveform generation for the demodulation / decoding of the signal. Essentially, it only needs some directives regarding the OOK waveform pulse structures, timelines, boundaries, etc. to process the signal, while most of the details regarding its generation are not necessary at the receiver. However, with several parameters influencing waveform generation for OOK-pulse-shaping using OFDM and multiple methods available to generate the OOK-pulse of a desired shape and form, vendors might end up using options for waveform generation that results in OOK pulse shapes and / or forms undesirable or unsuitable for demodulation in certain receivers. Therefore, it would be helpful to have certain standards or specifications to restrict the implementation to get results that are acceptable or well suitable to most if not all device types. In essence, the following reasons justify the specification of some restrictions or metrics regarding the OOK waveform structure:

[0199] - Wireless device implementation: With the specification of the requirement of the OOK-pulse shape and form, the wireless device implementation can be tailored to what is expected by it in terms of the received signal characteristics.

[0200] - Equipment testing: When a wireless device is tested, to evaluate viability and evaluate various communication metrics, standards regarding what is received are advantages. With numerous methods for implementation of OOK-pulse-shaping using OFDM, specifying the implementation methods themselves may not be desirable. However, standardizing what kind of OOK-waveform the implementation method should produce provides a benchmark for testing devices across vendors and network scenarios.

[0201] In the following, such restrictions and measurement metrics regarding the OOK pulse shape and form are discussed.

[0202] In certain embodiments, the wireless device is configured to transmit or to receive a signal, wherein the signal is based on an On-Off-Keying waveform that satisfies at least one of the following conditions:- The power of the signal within the chip duration of an ‘Off’ chip is at most pOff: On% of that of an ‘On’ pulse with the same chip duration or a different chip duration, wherein the value of p0ff.0n% is predetermined or fixed in a specification (e.g., 5G NR or 6G specification), or fixed as a capability of the wireless device or a wireless device type.

[0203] - The maximum amplitude of an ‘Off’ chip is at most aOff,max> wherein the value of aOff,max is predetermined or fixed in a specification (e.g., 5G NR or6G specification), or fixed as the capability of the wireless device or a wireless device type. In certain cases, aOff,max may be set relative to a value associated with the amplitude of an ‘On’ chip.

[0204] - The average amplitude of an ‘Off’ chip is at most aOff,avg> wherein the value ofaoff,avgis predetermined or fixed in the specification (e.g., 5G NR or 6G specification) or fixed as a capability of the wireless device or a wireless device type or of said wireless device or said wireless device type. In certain cases, aoff;avgmay be set relative to a value associated with the amplitude of an ‘On’ chip.

[0205] - The slope in the falling edge of the waveform transition from ‘On’ to ‘Off’ is at most ^•fall.max ■

[0206] - The slope in the rising edge of the waveform transition from ‘Off’ to ‘On’ is at least ^rise.min ■

[0207] In certain examples, the value of p0ff:0nis set toavalue less than or equal to 5.

[0208] In certain examples, the value of aoffmaxis set toavalue that is 1-20% of the value of the maximum amplitude of an ‘On’ chip aOn max°rthe average amplitude of an ‘On’ Chip Clon, Avg'

[0209] In certain examples, the value of aoffavgissetto a value that is 1-15% of the value of the maximum amplitude of an ‘On’ chip aOn max°rthe average amplitude of an ‘On’ Chip Clon, Avg'

[0210] In certain embodiments, the value of mfall maxis at least equal to tan (a°). In certain examples, the value of a is negative. In certain examples, the value of a is equal to less than -80.In certain embodiments, the value of mrise minis at least equal to tan (p°). In certain examples, the value of ft is positive. In certain examples, the value of is equal to or greater 80.

[0211] With one or more of the above directives, waveform characteristics can be limited to certain shape and form, thereby allowing for standardized testing across devices and scenarios.

[0212] Receiver-feedback-based waveform generation

[0213] In the description of the waveform generation above, there are multiple parameters that may be specified or left up to implementation. One key aspect that could be explored is the tailoring of the waveform according to feedback from the wireless device.

[0214] Timing offset information reporting

[0215] In wireless devices with reduced power consumption and reception capabilities, the peak power consumption is only few μW, or in some extreme cases be around just Due to limited power, typically cheap oscillators are used for clock generation leading to poor frequency accuracy, and hence sampling frequency errors.

[0216] The sampling process might be error prone in such low-power devices in the sense that the actual sampling frequency / s,actuaiduring an analog-to-digital conversion may not be equal to the value of the assumed or intended sampling frequency / s,originai- The deviation of the value ofs actualfrom / s,originaiatthe device may be expressed by the Sampling Frequency Offset, SFO. The value of SFO can be expressed in terms parts-per-million, ppm. For example, it may be expressed as 10xppm, wherein x is a positive real number. In some examples, x is a positive integer such as {1,2,3,5,

[0217]

[0218] The accumulation of sampling frequency offsets at the device over time results in a timing offset. Depending on the value of the SFO, the timing offset experienced or estimated by the device may differ. Typically, a higher SFO leads to a higher timing offset, thereby leading to higher decoding errors, false-detections and / or misdetections. For example, an OOK pulse can be detected at time t2ms, when in reality it starts at ms, denoting a detection or timing offset of t2-

[0219]

[0220] ms, where t < t2. Here t2- is the timing offset due to incorrect sampling frequency of the device clock, orthe accumulated timing offset. The determination or estimation of the timing offset may be performed using simple energy detection mechanisms and baseband processing of the on-off-keying pulses. With the amount of energy detected in one or more ‘On’ and / or ‘Off’ pulses, the intrusion from past pulses during transitions from ‘On-Off’ or ‘Off-On’ can be detected, which might help in estimating timing offsets or errors with respect to timing offsets. As low power devices may not be able to correct such errors, providing feedback to a network node (e.g., a reader) regarding the timing offsets may be used by the network to mute certain duration of the OOK waveform, or to pre-distort or to adjust the OOK transmission to alleviate issues due to the timing offsets. The adjustments at the transmitter side may involve the modification of the transmitted OOK-pulse-based waveform.

[0221] In such cases, a wireless device may be configured to feedback to the network node (or another wireless device) some information regarding at least one of the following: - timing offset value or

[0222] - information related to the timing offset value.

[0223] The terms ‘offset’ and ‘timing offset’ may have identical meaning and may be used interchangeably in this invention disclosure.

[0224] In the following, reporting information related to timing offset(s) by the wireless device is discussed.

[0225] In certain embodiments, the wireless device is configured to determine or estimate at least one timing offset value or information related to a timing offset value, wherein the timing offset value(s) denotes an offset of the radio frame at a certain predetermined or configured point in time of the radio frame with respect to a reference timing value(s) or position(s).

[0226] In certain examples, the timing offset or information regarding the timing offset may be estimated using the received signal (based on an On-Off-Keying waveform) at the wireless device.

[0227] In certain embodiments, the wireless device determines a timing offset value via receive, Rx, signal processing. In this case, the Rx signal processing may involve determining or estimating the amount of energy in a pulse known or predetermined to be ‘Off’ or a pulse known or predetermined to be ‘On’. With the estimated or determinedenergy in a supposedly ‘On’ or ‘Off’ pulse, especially during transitions from ‘On-Off’ or ‘Off-On’, the device may be able to estimate how much is its reception or processing timing deviated from that of the original timing reference of the waveform (i.e., the timing offset).

[0228] In certain embodiments, the wireless device is configured to provide, indicate or report to a network node, at least one timing offset value or information related to at least one timing offset value associated with one or more OOK pulses, wherein the timing offset value(s) or the information related to the timing offset value(s) may be determined by the wireless device with respect to one or more reference timing value(s) or position(s). In wireless devices with very low power consumption (e.g., device with approximately 1 [iW power consumption) accurate time tracking or calculation of the timing offset value(s) may not be possible due to limited power or hardware (e.g., memory) constraints. In such cases, the wireless device may be configured to indicate whether the offset determined by the device is greater than or less than a threshold offset value. In certain embodiments, the wireless device reports information related to a time offset using a 1 -bit indicator to a network node or another wireless device.

[0229] In some options, the threshold offset value is

[0230] - configured or indicated by the network node to the wireless device, or

[0231] - indicated by the wireless device to the network node, or

[0232] - predetermined or fixed in a standard specification (for e.g., pre-defined or fixed in a standard specification according to a device’s capability or type).

[0233] In some options, the information related to the timing offset reported or indicated by the wireless device comprises an indication of whether the determined timing offset value(s) is / are greater than or less than one or more threshold timing offset value(s). In certain embodiments, the timing offset, or the information related to the timing offset is provided, indicated or reported in the data or control information of a physical channel between the device and the network node (e.g., a reader).

[0234] As discussed above, the sampling frequency offset may have a cumulative effect over time resulting in the timing offset. In some cases, an expected threshold offset for a certain predetermined or presumed sampling frequency offset value at the wireless device may be assumed by the network (e.g., a network node) or set in the standardspecifications, which would then be used as the threshold offset value relative to which indications of information related to timing offsets are provided. A device that is expected or assumed to have a certain sampling frequency offset value based on its capability or its type may report information related to timing offsets values relative to its assumed or expected threshold offset value. In certain cases, a single sampling frequency offset value is assumed or fixed across wireless devices, which means that the threshold offset value is also fixed across wireless devices.

[0235] In some examples, a device’s type or capability may be associated with or assigned with a sampling frequency offset value in the standard specifications.

[0236] In some examples, a sampling frequency offset value at a wireless device may be associated with a threshold timing offset value in the standard specifications.

[0237] In some examples, a threshold timing offset value is given by a timing offset value that is associated with a sampling frequency offset of 10xppm, wherein x is a positive real number. In some examples, x e {1,2, 3,4,5, 6}. In some examples, the value of x is fixed for a wireless device or for a wireless device type or fixed in general for any wireless device.

[0238] In some other examples, the threshold timing offset value is given by a scalar multiple of a timing offset value associated with a sampling frequency offset of 10xppm, wherein x e {1,2, 3, 4, 5, 6}. In some examples, the scalar is denoted by y, wherein y < 1.

[0239] In certain embodiments, the wireless device is configured to provide, indicate or report a value or information related to the sampling frequency offset of a received signal at the wireless device. In an example, a sampling frequency offset value may be expressed in terms of 10xppm, and the value of x may be reported or indicated by the wireless device. In some cases, the values of x that could be reported by the wireless device are {

[0240]

[0241] 1,2,3,

[0242] In certain embodiments, the timing offset value or the information related to the timing offset value determined by the wireless device is indicated using a Z-bit indicator, wherein Z > 1.

[0243] In some examples, for Z = 1, a ‘0’ or T bit value is used to indicate the event where the determined timing offset value at the wireless device is greater than a thresholdoffset value and the other bit value (‘0’ if T is used to indicate the previous event and ‘T if ‘0’ is used to indicate previous event) is used to indicate the event where the determined timing offset value is less than a threshold offset value.

[0244] In certain embodiments, at least one of the following statements regarding the reference timing value / position apply:

[0245] - the reference timing value or time instant is fixed in the device or indicated to the wireless device by the network,

[0246] - the reference timing value or time instant is selected from a set of reference timing values / time instants and is indicated to the device in the control or data part of a physical channel between the network node (e.g., the reader) and the wireless device,

[0247] - the reference timing value or time instant is implicitly indicated from the network node (e.g., the reader) to the device, using at least one or more parameters indicated from the network node (e.g., the reader) to the device,

[0248] - the reference timing value or time instant is determined by the wireless device, - the reference timing value or time instant is determined by the wireless device using at least one or more parameters indicated from the network node (e.g., the reader) to the device,

[0249] - the reference timing value or time instant is a predetermined point or time instant in the radio frame transmitted from the network node to the wireless device.

[0250] In some examples, the reference timing value or time instant is the start of the radio frame transmitted from the network node to the wireless device.

[0251] In some examples, the reference timing value or position is the time instant at which the wireless device turns on its baseband part.

[0252] In some examples, the reference timing value is the time instant corresponding to the start of the physical channel between the network node (e.g., reader) and the wireless device.

[0253] In some examples, the reference timing value is the time instant corresponding to the start of the data or control part of the physical channel between the reader (network) and the wireless device.In some examples, the reference timing value is the time instant at which the device detects a second rising edge after prior detection of one rising edge and one falling edge.

[0254] In some examples, the reference timing value is the time instant at which the device detects a second falling edge after prior detection of one falling edge and one rising edge.

[0255] In some examples, the reference timing value is the time instant at which the device detects a second falling edge after prior detection of two rising edges and one falling edge.

[0256] In some examples, the reference timing value is the time instant at which the device detects a second rising edge after prior detection of two falling edges and one rising edge

[0257] In some examples, the reference timing value is K |is or ms ahead with respect to the start of the physical channel between the network node (e.g., reader) and the device, wherein K > 0. In some examples, the reference timing value is K |is or ms ahead with respect to the start of the data or control part of the physical channel, wherein K > 0. In certain embodiments, the wireless device determines a timing offset value as the difference between the time instant at which the wireless device detects a rising or falling edge of an OOK pulse and a reference timing value (which is associated with a reference timing position).

[0258] In certain embodiments, the OOK pulse or the rising or falling edge of the OOK pulse with which the timing offset is computed is configured / indicated by the network, or preconfigured / fixed in the specifications. In certain examples, the first detected OOK pulse by the wireless device or the first detected rising or falling edge of an OOK pulse by the wireless device is / are used to compute the timing offset value.

[0259] In some examples, the timing offset value is less than the duration of one OFDM symbol.

[0260] In some other examples, the timing offset value is less than the duration of one chip, i.e., the duration corresponding to one bit in the OOK-waveform.

[0261] In some other examples, the timing offset value is less than the duration of one chip.In some examples, the number of chips in a OFDM symbol, M, is predetermined (fixed) or configured or indicated to the wireless device by the network node.

[0262] In some examples, a timing offset value or information regarding a timing offset value is encoded between the preamble and the first midamble in a physical channel. In some examples, the timing offset value is encoded between two consecutive midambles in a physical channel. In some examples, the timing offset value is encoded between the last midamble and the postamble in a physical channel.

[0263] In certain embodiments, the timing offset values may be confined within a range of values from R1to R2, wherein the reference timing value and / or threshold offset value is contained within this range. For instance, R is the reference timing value (at the reference timing position) and R2is the maximum timing offset resulting from a sampling frequency offset of 10xppm, x e {1,2, 3,4,5, 6}. In another instance, R is the reference timing value (at a reference timing position) and R2is the timing offset value which is greater than the maximum timing offset resulting from a sampling frequency offset of 10xppm, x e {1,2, 3, 4, 5, 6], and wherein R < R2.

[0264] In some examples, 2Zoffset levels are defined in the range [ / ?1(R2], wherein R2> R and a given codepoint of the Z-bit indicator reported by the wireless device maps to one of the 2Zvalues. The quantization of the 2Zoffset levels in the given range may be uniform or non-uniform.

[0265] In some examples, 2Zoffset levels { / ?i, / ?i + 8, Rr+ 26,.... R-^ + (2Z- 1)8} are defined in the range [ / ?1(R2], wherein R2< R + (2Z- 1)8 and a given codepoint of the Z-bit indicator reported by the wireless device maps to one of the 2Zvalues.

[0266] Spreading information reporting

[0267] The delay spread of the wireless channels worsens the detection capability of low power wireless devices operating on OOK waveforms. For instance, an OOK pulse transmitted over a time duration of d ms, may be detected by the device over a time duration d2ms, which is longer than d ms due to multi-path channel ‘spreading’. Such channel spreading lead to an increase in the rate of misdetection of incoming signals, or false alarms. In such cases, the device may be equipped to or configured with mechanisms for feedback of spreading duration or spreading duration information. This information can be used by the network node (e.g., the reader) or transmitter to predistort or adjust the OOK-pulse-based transmission to alleviate the spreading issues.The adjustments at the transmitter side may involve the modification of the transmitted OOK-pulse-based waveform by muting certain duration(s) of the ‘ON’ pulses. For example, this can be performed by inserting zeros at the end of the bit-spreading sequence.

[0268] The terms ‘duration’, ‘time duration’ mean the same and are used interchangeably in this invention. The terms ‘duration’ or ‘time duration’ in certain contexts may refer to the duration of the one or more detected or received OOK pulse(s) or one or more reference OOK pulse(s).

[0269] In certain embodiments, the wireless device is configured to determine or estimate a spreading duration or information related to a spreading duration associated with one or more OOK pulses, wherein a spreading duration denotes a time difference between the duration of one or more received or detected OOK pulses and the duration of one or more reference OOK pulses.

[0270] In certain embodiments, the wireless device is configured to determine or estimate a spreading duration or spreading duration information for an ‘On’ pulse or an ‘Off’ pulse of the OOK signal. The estimation method may comprise at least one of the following operations: energy detection, filtering, application of comparators, edge detection, etc. The method essentially determines how much a transmitted pulse, with a predetermined or expected width, has ‘spread’ or ‘expanded’. For instance, during a transition from an ‘On’ pulse to an ‘Off’ pulse, the device may measure more than the expected energy in the ‘Off’ pulse duration, which may be a result of the wireless channel ‘spreading’ the energy from the ‘On’ pulse into the duration of the subsequent ‘Off’ pulse due to multipath propagation. Measurements of such spurious energy during pulse transitions may be cumulatively used to estimate the amount or duration of the energy spread, which could be used to adjust the width and energy of the ‘On’ pulse according to the spreading duration.

[0271] In certain embodiments, the wireless device is configured to provide, indicate or report to a network node, a spreading duration or information related to a spreading duration associated with one or more received or detected OOK pulses of the received signal, wherein the spreading duration(s) or information related to the spreading duration(s) may be determined by the wireless device with respect to one or more reference time duration(s) of one or more reference OOK pulse(s).In certain embodiments, the wireless device is configured to provide, indicate or report to a network node, a spreading duration or information related to a spreading duration, wherein the spreading duration(s) or information related to the spreading duration(s) may be determined by the wireless device with respect to one or more reference time durations of one or more reference OOK pulses of the received signal, and wherein the wireless device indicates whether the determined spreading duration(s) is / are greater than or less than one or more threshold spreading duration(s).

[0272] In certain embodiments, a threshold spreading duration is expressed in terms of the duration of the cyclic prefix length of one or more OFDM symbol(s) used in the generation of the OFDM signal.

[0273] In certain embodiments, a threshold spreading duration is

[0274] - configured or indicated by the network node to the wireless device, or

[0275] - indicated by the wireless device to the network node, or

[0276] - predetermined or fixed in a standard specification (for e.g., pre-defined or fixed in a standard specification according to a device’s capability or type).

[0277] In certain embodiments, a threshold spreading duration is less than or equal to the length of the cyclic prefix of one or more OFDM symbols. In some examples, the threshold spreading duration is a fraction of the cyclic prefix length of one or more OFDM symbols.

[0278] In certain embodiments, a threshold spreading duration is less than or equal to the time duration of a reference OOK pulse. The reference OOK pulse may have a chip duration corresponding to a predetermined, fixed or network-configured / indicated chip rate M. This might be the case for lower values of M, where the chip duration is higher and the ‘acceptable’ channel spread values may fall within the chip duration.

[0279] In certain embodiments, a threshold spreading duration is higher than or equal to the time duration of a reference OOK pulse. The reference OOK pulse may have a chip duration corresponding to a predetermined, fixed or network-configured / indicated chip rate M. This might be the case for higher values of M, where the chip duration is lower and the ‘acceptable’ channel spread values may go beyond the chip duration.

[0280] In certain embodiments, a threshold spreading duration is the time duration of one or more reference OOK pulse(s).In certain embodiments, a threshold spreading duration is greater than the time duration of one or more reference OOK pulse(s).

[0281] In some examples, a threshold spreading duration is the maximum duration or average time duration of one or more reference OOK pulses.

[0282] In certain embodiments, a threshold spreading duration is the time duration of one or more reference OOK pulse(s) added with a timing offset value. In some examples, the timing offset value is associated with a predetermined or assumed sampling frequency offset. In certain cases, the predetermined or assumed device sampling offset is expressed as 10xppm, wherein x e IR+. In some instances, x is fixed.

[0283] In certain embodiments, the information related to said spreading duration of an OOK pulse is reported to the network node using a Z'-bit indicator, wherein Z' > 1.

[0284] In certain embodiments, the spreading duration(s) or information related to the spreading duration(s) of the one or more detected or received OOK pulse(s) is / are indicated or provided to the network node.

[0285] In certain embodiments, the spreading duration(s) or the information related to the spreading duration(s) of the one or more detected or received OOK pulse(s) is / are indicated in the data or control information of a physical channel.

[0286] In some examples, for Z’ = 1, a ‘0’ or ‘T value is used to indicate the event where the determined spreading duration of the OOK pulse detected at the wireless device is greater than said threshold spreading duration value and the other bit value (‘0’ if ‘1’ used to indicate the previous event and ‘T if ‘0’ is used to indicate previous event) is used to indicate the event where the determined spreading duration of the OOK pulse detected at the wireless device is less than said threshold spreading duration.

[0287] In some examples, the time duration of a reference OOK pulse is determined by the wireless device during a

[0288] - timing recovery phase,

[0289] - timing acquisition phase,

[0290] - start-indication phase.

[0291] In some examples, the timing recovery or timing acquisition phase is when the device attempts to synchronize or adjust its clock based on a sequence of OOK pulsestransmitted by the network node. In some examples, the start indication phase is when the device is activated to detect the start of a radio frame or an OOK pulse signal. In some examples, the aforementioned phases may happen before reception of a physical channel.

[0292] In some examples, the time duration of the of the one or more reference OOK pulse(s) is determined or assumed by the wireless device as a time difference between a rising edge and a falling edge or a time difference between a falling edge and a rising edge. In some other examples, the time duration of the one or more reference OOK pulse(s) is known to the wireless device based on an indicated or pre-determined chip rate M, wherein M is defined as the number of OOK pulses or bits per OFDM symbol.

[0293] In some examples, the time duration information of the one or more received or detected OOK pulses is determined by the wireless device during the reception.

[0294] In some examples, the time duration(s) of the one or more received or detected OOK pulse(s) is / are determined by the wireless device as the time difference between a rising edge and a falling edge or the time difference between a falling edge and a rising edge of the one or more received or detected OOK pulses.

[0295] The wireless device receives multiple OOK pulses during the timing recovery phase, timing acquisition phase and the general control or data transmission phase, and the wireless device may determine the duration of one or more OOK pulse(s) received or detected during any of these phases.

[0296] In certain embodiments, the duration of the one or more reference OOK pulse(s) is determined by the wireless device as the maximum duration or average duration among all possible OOK pulse duration values determined by the wireless device during timing recovery phase or timing acquisition phase.

[0297] In certain embodiments, the duration of the one or more reference OOK pulse(s) is determined or decided based on a predetermined chip rate M used for the OOK pulse waveform in an OFDM symbol.

[0298] In certain embodiments, the chip rate M used to obtain the reference OOK pulse is the same as the chip rate M used for a OOK pulse with which the spreading duration information is determined, computed and / or reported.In some examples, the spreading duration(s) of one or more received or detected OOK pulse(s) is / are always less than the one or more reference OOK pulse duration(s). In some examples, the spreading duration(s) of one or more received or detected OOK pulse(s) is / are given as a fraction of the one or more reference OOK pulse duration(s). In certain embodiments, the possible spreading duration values may be confined within a range of values from S to S2, wherein the reference timing value is contained within this range. For instance, S is the reference duration value (of the reference OOK pulse) and S2is the maximum spreading duration resulting from a sampling frequency offset of 10xppm, x e {1,2, 3, 4, 5, 6} or channel delay spread.

[0299] In some examples, 2Z' spreading duration levels are defined in the range [Si, S2]> wherein S2> S and a given codepoint of the Z'-bit indicator reported by the wireless device maps to one of the 2Z' values. The quantization of the 2Z' offset levels in the given range may be uniform or non-uniform.

[0300] In some examples, 2Z' spreading duration levels {S1, S1+Y, S1+ 2y,..., S1+ (2Z' -l)y] are defined in the range [Si, S2] > wherein S2< S1+ (2Z' - l)y and a given codepoint of the Z'-bit indicator reported by the wireless device maps to one of the 2Z' values.

[0301] In some examples, the 2Z' spreading duration levels are uniformly or non-uniformly distributed in the interval [0, ds], where dsis the reference time duration(s) of one or more reference OOK pulse(s).

[0302] In some examples, the 2Z' levels are uniformly or non-uniformly distributed in the interval [0, ds], where p < 1. This method limits the reporting to only a fraction of the one or more reference time duration(s) of one or more reference OOK pulse(s).

[0303] Relative waveform adjustment indication

[0304] In the above methods regarding receiver feedback, values regarding timing offset or spreading were reported by the wireless device to a network node or another wireless device. In the following, we discuss wireless device commands for relative signal adjustments with respect to the current signal conditions.

[0305] In certain embodiments, the wireless device is configured to provide in a report an E-bit indicator to a network node, wherein the E-bit pattern indicates that the networknode increase or decrease the width of the OOK ‘On’ pulse of the signal by a predetermined amount or an amount indicated by said E-bit pattern, or maintain, i.e., do not change the width of an OOK ‘On’ pulse of the signal.

[0306] In certain embodiments, the wireless device expects to receive a transmission from a network node with adjusted ‘On’ pulse width, a predetermined or fixed time duration, te, after the transmission of the report / indication to a network node.

[0307] In an example, E = 2, and a bit pattern of ‘00’ may denote that the OOK ‘On’ pulse width of the signal is not changed, a bit pattern of ‘01’ may denote that the network node increase (or decrease) the width of OOK ‘On’ pulse of the signal by a predetermined amount of duration, and the bit patterns of ‘10’ and ‘1 T to denote that the network node decreases (or increases) the width of OOK ‘On’ pulse of the signal by a predetermined or fixed amount of duration.

[0308] In an example, E = 2, and a bit pattern of ‘00’ may denote that the OOK ‘On’ pulse width of the signal is not changed, a bit pattern of ‘01’ may denote that the network node increases (or decreases) the width of OOK ‘On’ pulse of the signal by a predetermined or fixed amount, and the bit pattern of ‘10’ denotes that the network node decrease (or increase) the width of an OOK ‘On’ pulse of the signal by a predetermined or fixed amount. The bit pattern ‘1T may be reserved.

[0309] When values of E > 2, the wireless device may indicate to a network node the amount by which the width of the OOK ‘On’ pulse of the signal is increased / decreased.

[0310] In certain embodiments, the wireless device is configured to provide a 7-bit report or indication to a network node, V > 1, wherein the V -bit pattern indicates that the network node advance or delay the transmission of the radio frame by a predetermined amount of time or an amount of time indicated by said 7-bit pattern, or maintain, i.e., do not change, the timing of the radio frame. This means that the radio frame transmission may be started in advance or delayed based on this feedback by the wireless device to compensate for the timing errors in it via external manipulation of the transmitted waveform.

[0311] In certain embodiments, the wireless device expects a delayed or advanced transmission from a network node of said predetermined or indicated amount of time,a predetermined or fixed time duration, tv, after the transmission of the report / indication to a network node.

[0312] In an example, V = 2, wherein a bit pattern of ‘00’ may denote that the timing of the radio frame is not changed. A bit pattern of ‘01’ may denote that the network advances (or postpones) the transmission of the radio frame by a predetermined amount. The bit patterns of ‘10’ and ‘1 T may denote that the network node postpones (or advances) the transmission of the radio frame by a predetermined or fixed amount.

[0313] In an example, V = 2, and a bit pattern of ‘00’ may denote that the timing of the radio frame is not changed. A bit pattern of ‘0T may denote that the network node advances (or postpones) the transmission of the radio frame by a predetermined amount. The bit pattern of ‘10’ may denote that the network node postpones (or advances) the transmission of the radio frame by a predetermined or fixed amount. The bit pattern ‘1 T may be reserved.

[0314] For values of V > 2, the wireless device may indicate to a network node the amount by which the transmission of the radio frame needs to be postponed or advanced by the network node.

[0315] It is to be noted that any report or indication of a value that is provided or transmitted by a wireless device may be performed to a network node. The network node receiving the report or indication may be different from the network node that performs any transmission to the wireless device, or the two network nodes could be identical. In certain cases, any measurement or determination of one or more parameters or values that the wireless device obtains from a reception may be obtained from a network node ‘A’, and any reporting of said determined parameter or values or information regarding the same may be provided or transmitted (or received by) the same network node ‘A’ or a different network node ‘B’.

[0316] It is also to be noted that, in this disclosure, any discussion regarding transmissions, reporting, indication, receptions, etc. that a wireless device is described to perform to or from a network node may also be performed to or from another wireless device. In certain cases, the other wireless device may be a user equipment (UE).

[0317] Referring to Figure 5, there is illustrated a method (500) performed by a wireless device according to some of the previously described embodiments. The methodcomprises receiving (501) a signal based on Orthogonal Frequency Division Multiplexing, OFDM, wherein M > 1 bits are modulated onto an OFDM symbol of the signal by at least the following steps:

[0318] o a first Q -length real-valued or complex-valued sequence or vector is determined using the M bits, where Q = ML and L > 1, and L is an integer number;

[0319] o a second sequence or vector of length D > 1 is determined using at least the first Q -length sequence or vector and a discrete Fourier-based transform; and

[0320] o a mapping of one or more entries to C > 1 resource elements or subcarriers in a frequency domain of the OFDM symbol is performed, wherein the one or more entries are

[0321] ■ entries of the second sequence or vector, or

[0322] ■ based on an element-wise-multiplication of entries of the second sequence or vector with a D -length real-valued or complex-valued third vector.

[0323] In some embodiments, it is disclosed a method performed by a wireless device. The method comprises:

[0324] o receiving a signal based on an on-off-keying, OOK, pulse waveform from a network node, wherein the signal comprises one or more OOK pulses; o determining from the signal a timing offset value or information related to a timing offset value, wherein the timing offset value or information related to the timing offset value is based on at least a difference between a time instant at which the wireless device detects a risi ng / fal ling edge of an OOK pulse of the one or more OOK pulses and a reference timing value; and o reporting the timing offset value or information related to the timing offset value to a network node.

[0325] Optionally, the network node transmitting the signal based on the on-off-keying, OOK, pulse waveform may be the same network node receiving the timing offset value or information related to the timing offset value. Optionally, the network node transmitting the signal based on the on-off-keying, OOK, pulse waveform may be a differentnetwork node from the network node receiving the timing offset value or information related to the timing offset value.

[0326] In some embodiments, the reference timing value is associated with a reference timing position.

[0327] In some embodiments, the reference timing position is fixed or indicated to the wireless device by the network node.

[0328] In some embodiments, the timing offset value is less than the duration of one chip, wherein the duration of one chip is predetermined or fixed, or configured / indicated to the wireless device by the network node, or determined by the wireless device.

[0329] In some embodiments, the timing offset value or the information related to the timing offset value determined by the wireless device is indicated using a Z-bit indicator, wherein Z > 1.

[0330] In some embodiments, the information related to the timing offset value comprises an indication of whether the determined timing offset value is greater than or less than a threshold offset value, wherein the threshold offset value is configured or indicated by the network node to the wireless device, or indicated by the wireless device to the network node, or predetermined or fixed.

[0331] In some embodiments, wherein the threshold offset value is a timing offset value that is associated with a sampling frequency offset of 10xppm, wherein x e {1,2, 3, 4, 5, 6}. In some embodiments, it is disclosed a method performed by a wireless device. The method comprises:

[0332] o receiving a signal based on an on-off-keying, OOK, pulse waveform from a network node, wherein the signal comprises one or more OOK pulses; o determining from the signal a spreading duration or information related to a spreading duration, wherein the spreading duration or information related to a spreading duration is based on a time difference between a time duration of one or more received or detected OOK pulses and a time duration of one or more reference OOK pulses; and

[0333] o reporting the spreading duration or information related to the spreading duration to a network node.Optionally, the network node transmitting the signal based on the on-off-keying, OOK, pulse waveform may be the same network node receiving the spreading duration or information related to the spreading duration. Optionally, the network node transmitting the signal based on the on-off-keying, OOK, pulse waveform may be different from the network node receiving the spreading duration or information related to the spreading duration.

[0334] In some embodiments, the time duration of the one or more reference OOK pulses is determined or decided based on a predetermined chip rate M used for the OOK pulse waveform in an Orthogonal Frequency Division Multiplexing, OFDM, symbol.

[0335] In some embodiments, the time duration of the one or more received or detected OOK pulses is determined by the wireless device as the time difference between a rising edge and a falling edge or the time difference between a falling edge and a rising edge of the one or more received or detected OOK pulses.

[0336] In some embodiments, the information related to the spreading duration of the one or more received or detected OOK pulses is reported to the network node using Z'-bit indicator, wherein Z' > 1.

[0337] In some embodiments, the information related to the spreading duration comprises indication of whether the determined spreading duration is greater than or less than a threshold spreading duration, wherein the threshold spreading duration is determined by the wireless device based on one or more reference OOK pulses or configured or indicated by the network node to the wireless device, or indicated by the wireless device to the network node, or predetermined / fixed.

[0338] In some embodiments, the threshold spreading duration is the time duration of the one or more reference OOK pulses.

[0339] In some embodiments, the time duration of the one or more reference OOK pulses is determined by the wireless device as the maximum duration or average duration among all possible OOK pulse duration values determined by the wireless device during timing recovery phase or timing acquisition phase.

[0340] In order to perform the previously described process or method steps performed by the wireless or UE there is also provided a wireless device. Figure 7 illustrates a block diagram depicting a wireless device (such as a UE or an IoT device) 1000. The wirelessdevice 1000 comprises a processor 1010 or processing circuit or a processing module or a processor means 1010; a receiver circuit or receiver module 1040; a transmitter circuit or transmitter module 1050; a memory module 1020, optionally a transceiver circuit or transceiver module 1030 which may include the transmitter circuit 1050 and the receiver circuit 1040. The wireless device 1000 further comprises an antenna system 1060 which includes antenna circuitry for transmitting and receiving signals to / from at least the network node or other wireless device(s). The antenna system employs beamforming as previously described.

[0341] The wireless device 1000 may belong to any radio access technology including 4G or LTE, LTE-A, 5G, advanced 5G or a combination thereof that support beamforming technology. The wireless device comprising the processor and the memory contains instructions executable by the processor, whereby the wireless device 500 is operative or is configured to perform any one of the embodiments related to the wireless device as previously described.

[0342] The processing module / circuit 1010 includes a processor, microprocessor, an application specific integrated circuit (ASIC), field programmable gate array (FPGA), or the like, and may be referred to as the “processor.” The processor 1010 controls the operation of the wireless device and its components. Memory (circuit or module) 1020 includes a random-access memory (RAM), a read only memory (ROM), and / or another type of memory to store data and instructions that may be used by processor 1010. In general, it will be understood that the wireless device 1000 in one or more embodiments includes fixed or programmed circuitry that is configured to carry out the operations in any of the embodiments disclosed herein.

[0343] In at least one such example, the processor 1010 includes a microprocessor, microcontroller, DSP, ASIC, FPGA, or other processing circuitry that is configured to execute computer program instructions from a computer program stored in a non-transitory computer-readable medium that is in or is accessible to the processing circuitry. Here, “non-transitory” does not necessarily mean permanent or unchanging storage, and may include storage in working or volatile memory, but the term does connote storage of at least some persistence. The execution of the program instructions specially adapts or configures the processing circuitry to carry out the operations disclosed in this disclosure relating to the wireless device. Further, it will be appreciated that the wireless device 1000 may comprise additional components.The wireless device 1000 by means of processor 1010 executes instructions contained in the memory 1020 whereby the wireless device is operative to perform any one of the previously described embodiments related to the actions performed by the wireless device, some of which are presented in the present disclosure.

[0344] There is also provided a computer program comprising instructions which when executed by the processor 1010 of the wireless device cause the processor 1010 to carry out the method as described herein.

[0345] Referring to Figure 6, there is illustrated a method (600) performed by a network node for generating a signal based on Orthogonal Frequency Division Multiplexing, OFDM, wherein M > 1 bits are modulated onto an OFDM symbol, the method comprising the following steps:

[0346] o determining (601) a first Q-length real-valued or complex-valued sequence or vector using the M bits, where Q = ML and L > 1, and L is an integer number;

[0347] o determining (602) a second sequence or vector of length D > 1 using at least the first Q -length sequence or vector and a discrete Fourier-based transform;

[0348] o performing (603) a mapping of one or more symbols or entries to C > 1 resource elements or subcarriers in the frequency domain of the OFDM symbol, wherein the one or more entries are

[0349] ■ entries of the second sequence or vector, or

[0350] ■ based on an element-wise-multiplication of entries of the second sequence or vector with a D -length real-valued or complex-valued third vector; and

[0351] transmitting (604) the signal to a wireless device.

[0352] In order to perform the previously described process or method steps performed by the network node there is also provided a network node. Figure 8 illustrates a block diagram depicting a network node 1100. The network node 1100 comprises a processor 1110 or processing circuit or a processing module or a processor means 1110; a receiver circuit or receiver module 1140; a transmitter circuit or transmitter module 1150; a memory module or a memory 1120, optionally a transceiver circuit or transceiver module 1130 which may include the transmitter circuit 1150 and the receiver circuit 1140. The network node 1100 further comprises an antenna system1160 which includes antenna circuitry for transmitting and receiving signals to / from at least the wireless device. The antenna system employs beamforming as previously described.

[0353] The network node 1100 may belong to any radio access technology including 4G or LTE, LTE-A, 5G, advanced 5G or a combination thereof that support beamforming technology. The network device comprising the processor and the memory contains instructions executable by the processor, whereby the network node 1100 is operative or is configured to perform any one of the embodiments related to the network node 1100 as previously described.

[0354] The processing module / circuit 1110 includes a processor, microprocessor, an application specific integrated circuit (ASIC), field programmable gate array (FPGA), or the like, and may be referred to as the “processor.” The processor 1110 controls the operation of the network node and its components. Memory (circuit or module) 1120 includes a random-access memory (RAM), a read only memory (ROM), and / or another type of memory to store data and instructions that may be used by processor 1110. In general, it will be understood that the network node in one or more embodiments includes fixed or programmed circuitry that is configured to carry out the operations in any of the embodiments disclosed herein.

[0355] In at least one such example, the processor 1110 includes a microprocessor, microcontroller, DSP, ASIC, FPGA, or other processing circuitry that is configured to execute computer program instructions from a computer program stored in a non-transitory computer-readable medium that is in or is accessible to the processing circuitry. Here, “non-transitory” does not necessarily mean permanent or unchanging storage, and may include storage in working or volatile memory, but the term does connote storage of at least some persistence. The execution of the program instructions specially adapts or configures the processing circuitry to carry out the operations disclosed in this disclosure relating to the wireless device. Further, it will be appreciated that the wireless device 1100 may comprise additional components. The network node 1100 may also be viewed as a Transmitter and Receiver Point (TRP).

[0356] The network node 1100 by means of processor 1110 executes instructions contained in the memory 1120 whereby the network node 1100 is operative to perform any oneof the previously described embodiments related to the actions performed by the network node.

[0357] There is also provided a computer program comprising instructions which when executed by the processor 1110 of the network node cause the processor 1110 to carry out the method as presented in the present description.

[0358] According to an embodiment, the network node (1100) comprising a processor (1110) and a memory (1120) containing instructions executable by said processor (1110), whereby the network node (1100) is operative to perform the method as described above

[0359] Reference throughout this specification to “an example” or “exemplary” means that a particular feature, structure, or characteristic described in connection with the example is included in at least one embodiment of the present technology. Thus, appearances of the phrases “in an example” or the word “exemplary” in various places throughout this specification are not necessarily all referring to the same embodiment.

[0360] Throughout this disclosure, the word "comprise" or “comprising” has been used in a non-limiting sense, i.e., meaning "consist at least of". Although specific terms may be employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. The embodiments herein may be applied in any wireless systems including LTE or 4G, LTE-A (or LTE-Advanced), 5G, advanced 5G, WiMAX, WiFi, satellite communications, TV broadcasting etc.

Claims

1. CLAIMS1. A method (500) performed by a wireless device (1000), the method comprising receiving (501) a signal based on Orthogonal Frequency Division Multiplexing, OFDM, wherein M > 1 bits are modulated onto an OFDM symbol of the signal by at least the following steps:o a first Q -length real-valued or complex-valued sequence or vector is determined using the M bits, where Q = ML and L > 1, and L is an integer number;o a second sequence or vector of length D > 1 is determined using at least the first Q -length sequence or vector and a discrete Fourier-based transform; ando a mapping of one or more entries to C > 1 resource elements or subcarriers in a frequency domain of the OFDM symbol is performed, wherein the one or more entries are■ entries of the second sequence or vector, or■ based on an element-wise-multiplication of entries of the second sequence or vector with a D -length real-valued or complex-valued third vector.

2. The method of claim 1, wherein M is a chip rate of the OFDM symbol, the chip rate corresponding to a number of chips of the OFDM symbol.

3. The method of claim 1 or 2, wherein, for a given value of M, a minimum number of physical resource blocks, PRBs, Z„inis allocated.

4. The method of claim 3, wherein a minimum value of L for a given value of M is given as a function of Zin, M and NBB, wherein NBBdenotes the number of subcarriers in a PRB.

5. The method of any of claims 1-4, wherein, D = Q or D = Q', wherein Q' > Q.

6. The method of any of claims 1 -5, wherein, the value of C is greater than or less than or equal to D.

7. A method performed by a wireless device (1000), wherein the method comprises:o receiving a signal based on an on-off-keying, OOK, pulse waveform from a network node, wherein the signal comprises one or more OOK pulses; o determining from the signal a timing offset value or information related to a timing offset value, wherein the timing offset value or information related to the timing offset value is based on at least a difference between a time instant at which the wireless device (1000) detects a rising / falling edge of an OOK pulse of the one or more OOK pulses and a reference timing value; ando reporting the timing offset value or information related to the timing offset value to a network node.

8. The method of claim 7, wherein the reference timing value is associated with a reference timing position.

9. The method of claim 8, wherein the reference timing position is fixed or indicated to the wireless device (1000) by the network node.

10. The method of claim 7, wherein the timing offset value is less than the duration of one chip, wherein the duration of one chip is predetermined or fixed, or configured / indicated to the wireless device (1000) by the network node, or determined by the wireless device (1000).

11. The method of claim 7, wherein the timing offset value or the information related to the timing offset value determined by the wireless device (1000) is indicated using a Z-bit indicator, wherein Z > 1.

12. The method of claim 7, wherein the information related to the timing offset value comprises an indication of whether the determined timing offset value is greater than or less than a threshold offset value, wherein the threshold offset value is configured or indicated by the network node to the wireless device (1000), orindicated by the wireless device (1000) to the network node, or predetermined or fixed.

13. The method of claim 12, wherein the threshold offset value is a timing offset value that is associated with a sampling frequency offset of 10xppm, wherein x e {1,2, 3, 4, 5, 6}.

14. A method performed by a wireless device (1000), wherein the method comprises:o receiving a signal based on an on-off-keying, OOK, pulse waveform from a network node, wherein the signal comprises one or more OOK pulses; o determining from the signal a spreading duration or information related to a spreading duration, wherein the spreading duration or information related to a spreading duration is based on a time difference between a time duration of one or more received or detected OOK pulses and a time duration of one or more reference OOK pulses; ando reporting the spreading duration or information related to the spreading duration to a network node.

15. The method of claim 14, wherein the time duration of the one or more reference OOK pulses is determined or decided based on a predetermined chip rate M used for the OOK pulse waveform in an Orthogonal Frequency Division Multiplexing, OFDM, symbol.

16. The method of claim 14 or 15, wherein the time duration of the one or more received or detected OOK pulses is determined by the wireless device (1000) as the time difference between a rising edge and a falling edge or the time difference between a falling edge and a rising edge of the one or more received or detected OOK pulses.

17. The method of any of claims 14-16, wherein the information related to the spreading duration of the one or more received or detected OOK pulses is reported to the network node using Z'-bit indicator, wherein Z' > 1.

18. The method of any of claims 14-17, wherein the information related to the spreading duration comprises indication of whether the determined spreading duration is greater than or less than a threshold spreading duration, wherein the threshold spreading duration is determined by the wireless device (1000) based on the one or more reference OOK pulses or configured or indicated by the network node to the wireless device (1000), or indicated by the wireless device (1000) to the network node, or fixed.

19. The method of claim 18, wherein the threshold spreading duration is the time duration of the one or more reference OOK pulses.

20. The method of any of claims 14-19, wherein the time duration of the one or more reference OOK pulses is determined by the wireless device (1000) as the maximum duration or average duration among all possible OOK pulse duration values determined by the wireless device (1000) during timing recovery phase or timing acquisition phase.

21. A method (600) performed by a network node (1100) for generating a signal based on Orthogonal Frequency Division Multiplexing, OFDM, wherein M > 1 bits are modulated onto an OFDM symbol, the method comprising:o determining (601) a first Q-length real-valued or complex-valued sequence or vector using the M bits, where Q = ML and L > 1, and L is an integer number;o determining (602) a second sequence or vector of length D > 1 using at least the first Q -length sequence or vector and a discrete Fourier-based transform;o performing (603) a mapping of one or more symbols or entries to C > 1 resource elements or subcarriers in the frequency domain of the OFDM symbol, wherein the one or more entries are■ entries of the second sequence or vector, or■ based on an element-wise-multiplication of entries of the second sequence or vector with a D -length real-valued or complex-valued third vector; ando transmitting (604) the signal to a wireless device (1000).

22. A wireless device (1000) comprising a processor (1010) and a memory (1020) containing instructions executable by said processor (1010), whereby the wireless device (1000) is operative to perform the method according to any of claims 1-20.

23. A network node (1100) comprising a processor (1110) and a memory (1120) containing instructions executable by said processor (1110), whereby the network node (1100) is operative to perform the method according to claim 21.

24. The wireless device (1000) according to claim 22, wherein the wireless device (1000) is an Internet of Things, loT, device.

25. The network node (1100) according to claim 23, wherein the network node (1100) is a gNB.

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