Methods for ambient internet of things (IOT) reader-to-device (R2D) link waveform design

Abstract

In accordance with implementations, a wireless device encodes a first information bit and a second information bit. The wireless device generates a first signal by mapping a first encoded bit to a first time domain symbol and a second encoded bit to a second time domain symbol. The first encoded bit is 1, and the second encoded bit is 0. A first beginning portion of the first time domain symbol, a first ending portion of the first time domain symbol, a second beginning portion of the second time domain symbol, and a second ending portion of the second time domain symbol are the same. The wireless device generates an orthogonal frequency division multiplexed (OFDM) symbol including a cyclic prefix (CP) based on the first signal. The first signal includes the first time domain symbol and the second time domain symbol. The wireless device transmits the OFDM symbol.

Description

Methods for Ambient Internet of Things (IoT) Reader-to- Device (R2D) Link Waveform Design PRIORITY CLAIM AND CROSS-REFERENCE

[0001] This application claims priority to U.S. Provisional Application No. 63 / 574,567, filed on April 4, 2024, and entitled “Methods for Ambient Internet of Things (IoT) Reader-to-Device (R2D) link waveform design,” U.S. Provisional Application No. 63 / 680,960, filed on August 8, 2024, and entitled “Methods for Ambient Internet of Things (IoT) Reader-to-Device (R2D) Link Waveform Design,” and U.S. Provisional Application No.63 / 767,267, filed on March 5, 2025, and entitled “Methods for Ambient Internet of Things (IoT) Reader-to-Device (R2D) link waveform design,” applications of which are hereby incorporated by reference herein as if reproduced in their entireties. TECHNICAL FIELD

[0002] The present disclosure relates generally to wireless communications, and, in particular embodiments, to systems and methods for Ambient Internet of Things (IoT) waveform design. BACKGROUND

[0003] Within the framework of Release 19, 3GPP is studying a new device, so-called Ambient Internet of Things (IoT) device, aiming at expanding the 5G New-Radio device ecosystem. In comparison with a conventional 3GPP cellular IoT device (for example, Narrowband IoT), Ambient IoT devices are not powered by traditional batteries and have ultra-low complexity and power consumption. Such devices are characterized by their small form factor and capability to harvest energy sources from the environment such as electromagnetic waves, solar or light, kinetic or vibration, wind, thermal, among others. Additionally, these devices may be equipped with limited energy storage (e.g., supercapacitors) for storing electric energy harvested from the ambient energy sources. As a result, high maintenance costs and safety hazards due to manual changing or recharging batteries on individual IoT devices can be eliminated, leading to an eco- friendly and sustainable technology of the future, reducing the carbon footprint of today’s supply chain.

[0004] Ambient IoT devices, also known as ambient intelligence or ambient computing devices, are a subset of IoT devices that operate in the background, using sensors, data analytics, and connectivity to create intelligent and adaptive environments. These devices are often unobtrusive, embedded in our surroundings, and provide a continuous flow of data that can be analyzed and acted upon to improve various aspects of our lives. Ambient IoT devices are characterized by their ability to collect data from FW 6000699PCT03 1their surroundings, process it, and respond autonomously to changing conditions, making them well-suited for a variety of applications where automation and adaptability are important.

[0005] Ambient IoT technology enables massive deployment of battery-free and low- cost IoT devices, which opens a whole new world of use cases and provides added value across the entire supply chain. To date, 3GPP groups Ambient IoT use cases into four broad categories, viz. inventory, sensor, positioning, and command. The inventory and command use cases are selected for studies in Release 19.

[0006] In the 3GPP Release-19 study scope, an Ambient IoT device can connect either directly to a gNode B or indirectly via an intermediate node, an assisting node or a user equipment (UE). The former network connectivity structure is referred to as Topology 1 (gNode B ↔ Ambient IoT Device) and the latter is Topology 2 (gNode B ↔ Intermediate Node ↔ Ambient IoT). Two additional network connectivity topologies are documented in [2], namely Topology 3 (gNode B ↔ Assisting Node ↔ Ambient IoT Device ↔ gNode B), and Topology 4 (UE ↔ Ambient IoT Device). Even though Topologies 3 and 4 are considered out of scope in the current release, the embodiments described herein are applicable to all the aforementioned topologies.

[0007] In 3GPP discussions, the link from a gNode B or a UE to an AIoT device is defined as reader to device (R2D) link, and the link from an AIoT device to a gNode B or a UE is defined as a device to reader (D2R) link. The implementations described herein relate to the signal waveform for the R2D link.

[0008] In current systems, the slightly longer cyclic prefix (CP) of the first orthogonal frequency-division multiplexing (OFDM) symbol in a subframe is ignored, and the duration of each OFDM symbol including the CP is evenly divided into M portions for modulating On-Off keying (OOK) symbols. The OOK symbols that overlap with the CP are skipped, or not modulated with OOK information bits. This resulted in a uniform OOK symbol spacing across OFDM symbol boundaries. However, the device needs to be informed of the location of the OOK symbols skipped either through signaling or standard definition.

[0009] Once the OOK information bits are mapped to a sampled time series within each OFDM symbol, the time series is transformed into frequency domain using Discrete Fourier Transformation (DFT). The frequency domain signal is pulse shaped and truncated to occupy only the allocated frequency resources in terms of subcarriers. Then, it is combined with other new radio (NR) transmission signals. The total signal is then transformed back into time domain using inverse Fast Fourier Transform (iFFT). The time domain signal is transmitted after inserting the CP. FW 6000699PCT03 2SUMMARY

[0010] Technical advantages are generally achieved, by implementations of this disclosure which describe methods, apparatus, and system.

[0011] In accordance with implementations, a wireless device (e.g., a WTRU) generates a first signal by mapping a first encoded bit to a first time domain symbol and a second encoded bit to a second time domain symbol. The first signal includes the first time domain symbol and the second time domain symbol. The first encoded bit is 1, and the second encoded bit is 0. A first beginning portion of the first time domain symbol, a first ending portion of the first time domain symbol, a second beginning portion of the second time domain symbol, and a second ending portion of the second time domain symbol are the same. he wireless device generates an orthogonal frequency division multiplexed (OFDM) symbol including a cyclic prefix (CP) based on the first signal. The wireless device transmits the OFDM symbol.

[0012] In some implementations, the wireless device may encode a first information bit and a second information bit into a plurality of encoded bits including the first encoded bit and the second encoded bit. The first information bit may be 1, and the second information bit may be 0. Or, the first information bit may be 0, and the second information bit may be 1.

[0013] In some implementations, the first information bit may be encoded into a first codeword comprising two encoded bits [1, 0], and the second information bit may be encoded into a second codeword comprising one encoded bit [0].

[0014] In some implementations, the first codeword and the second codeword may each further comprise one or more additional encoded bits of 1 at a first beginning of the first codeword and a second beginning of the second codeword.

[0015] In some implementations, the first information bit and the second information bit may be encoded into a first codeword and a second codeword based on Manchester encoding.

[0016] In some implementations, the first encoded bit and the second encoded bit may be the same as the first information bit and the second information bit, respectively.

[0017] In some implementations, symbol durations of the first time domain symbol and the second time domain symbol may be the same.

[0018] In some implementations, the first time domain symbol may be a constant high value over a first symbol duration of the first time domain symbol. The second time domain symbol may include a first transition from the constant high value to a constant low value after a first duration corresponding to the second beginning portion of the second time domain symbol. The second time domain symbol may further include a second transition from the constant low value to the constant high value starting at a FW 6000699PCT03 3second duration corresponding to the second end portion of the second time domain symbol.

[0019] In some implementations, the first information bit may be encoded into a first codeword comprising two encoded bits [0, 1]. The second information bit may be encoded into a second codeword comprising one encoded bit [1], respectively.

[0020] In some implementations, the first codeword and the second codeword may each further comprise one or more additional encoded bits of 0 at a first beginning of the first codeword and a second beginning of the second codeword.

[0021] In some implementations, the second time domain symbol may be a constant high value over a second symbol duration of the second time domain symbol. The first time domain symbol may include a first transition from the constant high value to a constant low value after a first duration corresponding to the first beginning portion of the first time domain symbol. The first time domain symbol may further include a second transition from the constant low value to the constant high value starting at a second duration corresponding to the second end portion of the first time domain symbol.

[0022] In some implementations, the first duration and the second duration may be selected to correspond to at least a duration of the CP in the OFDM symbol.

[0023] In some implementations, numbers of the one or more additional encoded bits for the first codeword and the second codeword may be the same.

[0024] In some implementations, numbers of the one or more additional encoded bits for the first codeword and the second codeword may be different.

[0025] In some implementations, to generate the OFDM symbol, the wireless device may generate one or more second signals from the first signal. Each of the one or more second signals may have a duration corresponding to an OFDM symbol duration of the OFDM symbol including the cyclic prefix. The wireless device may generate one or more third signals from the one or more second signals by removing a number of samples corresponding to a CP duration from a corresponding beginning of each of the one or more second signals. The wireless device may generate a frequency domain representation of the one or more third signals. The wireless device may apply the frequency domain representation to one or more subcarriers of an OFDM generator function.

[0026] In some implementations, generating the frequency domain representation is based on at least one of a discrete Fourier transform (DFT) operation or mapping from one of the one or more third signals to one or more pre-stored or pre-generated frequency domain representations.

[0027] In some implementations, the one or more third signals may be further modified to reverse an operation of OFDM symbol windowing. FW 6000699PCT03 4

[0028] In some implementations, the OFDM generator function may comprise at least one of inverse fast Fourier transform (iFFT) operation, CP insertion, digital-to- analog conversion (DAC), or frequency domain upconversion.

[0029] In some implementations, the frequency domain representation may be any of a modified representation or a filtered representation before the applying the frequency domain representation to the one or more subcarriers.

[0030] In some implementations, to transmit the OFMD symbol, the wireless device may transmit the OFDM symbol including the CP over a physical reader to device channel (PRDCH).

[0031] In accordance with implementations, a wireless device (e.g., a WTRU) assembles respective information bits for each orthogonal frequency division multiplexed (OFDM) symbol based on information bits in a message for a plurality of OFDM symbols to generate assembled information bits for each OFDM symbol. The wireless device generates a time domain waveform for each OFDM symbol based on the assembled information bits for each OFDM symbol. The wireless device cyclic shifts the time domain waveform for each OFDM symbol. After the cyclic shifting, the wireless device transforms the time domain waveform for each OFDM symbol to generate complex modulation values for each OFDM symbol. The wireless device generates subcarrier modulation values based on the complex modulation values. The wireless device applies a phase rotation to the subcarrier modulation values.

[0032] In some implementations, to assemble the respective information bits, the wireless device may determine a repeating or redundant bit index for an OFDM symbol based on a cyclic shift value of a previous OFDM symbol. The wireless device may insert a repeating or redundant bit at a bit position based on the repeating or redundant bit index in the OFDM symbol. The repeating or redundant bit may have a same value as an incomplete bit of the previous OFDM symbol.

[0033] In some implementations, to assemble the respective information bits, the wireless device may determine a repeating or redundant bit index for an OFDM symbol based on a repeating or redundant bit index lookup table, a number of On-Off Keying (OOK) symbols per OFDM symbol, and a position of the OFDM symbol in the message. The wireless device may insert a repeating or redundant bit at a bit position based on the repeating or redundant bit index in the OFDM symbol. The repeating or redundant bit may have a same value as an incomplete bit at an end of a previous OFDM symbol.

[0034] In some implementations, to cyclic shift the time domain waveform for each OFDM symbol, the wireless device may determine a cyclic shift value for an OFDM symbol in the message based on cyclic prefix (CP) lengths of previous OFDM symbols in FW 6000699PCT03 5the message, a CP length of the OFDM symbol, and a length of each OOK symbol in number of discrete Fourier transform (DFT) samples.

[0035] In some implementations, the cyclic shift value for the OFDM symbol in the message may be based on the following. ^^^^^^^^^^^ = ^^^ ^^ ^^^^^^ , 2^^^^^^^^

[0036] ^^^^^^^^^^index to a k-th OFDM symbol in the message. ^^^^^^may be the CP length of an i-th OFDM symbol in the message in number of DFT samples. ^^^^may be the length of each OOK symbol in number of DFT samples.

[0037] In some implementations, to cyclic shift the time domain waveform for each OFDM symbol, the wireless device may determine a cyclic shift value for an OFDM symbol based on a cyclic shift value lookup table, a number of On-Off Keying (OOK) symbols per OFDM symbol, and a position of the OFDM symbol in the message.

[0038] In some implementations, to apply the phase rotation, the wireless device may determine a phase rotation value for an OFDM symbol in the message based on a previous phase rotation value of a previous OFDM symbol, a CP length of the OFDM symbol, a starting frequency index, a number of subcarriers, and a Fast Fourier Transform (iFFT) size.

[0039] In some implementations, the phase rotation value may be based on the following. "#∙%&'( * ^ ^^ ^ − 1 + ) +,)-*^.∙ / (0 ^^ 1^ = 0, ^^^^ = ^^ ^

[0040] ^^^^may be the phase rotation value. k may be an index to a k-th OFDM symbol in the message. ^4^may be the number of subcarriers allocated for transmitting the message, ^^^^^^ is the CP length of the k-th OFDM symbol. ^^++5may be the iFFT size, and 67"8∈{0,1,2,…, NiFFT -NSC}.

[0041] In accordance with implementations, a wireless device (e.g., a WTRU) receives a second message using a second data rate. The second message comprises a first set of bits. The wireless device determines a second set of bits by discarding one or more bits in the first set of bits.

[0042] In some implementations, the first data rate may be a low data rate that does not require additional handling capability. The second data rate may be a high data rate that requires the additional handling capability at the wireless device. FW 6000699PCT03 6

[0043] In some implementations, the first set of bits may be a set of Manchester encoded bits or chips.

[0044] In some implementations, the wireless device may determine a third set of bits by skipping one or more chips every M chips in the first set of bits. M is a number of On-Off keying (OOK) chips per OFDM symbol. The wireless device may decode a fourth set of bits from the third set of bits based on Manchester encoding. The wireless device may determine the second set of bits by discarding one or more bits in the fourth set of bits.

[0045] In some implementations, a number of the one or more chips or bits to be skipped or discarded may be received in one of a configuration message or a preamble preceding the second message.

[0046] In some implementations, a number of the one or more chips or bits to be skipped or discarded may be determined based on any of M, a data rate indication, a subcarrier spacing, or an OFDM symbol duration.

[0047] In some implementations, any of the first set of bits or the second set of bits may include encoded chips or information bits.

[0048] In this way, this disclosure provides the technical solutions for technical problems of waveform design in implementing OOK modulation. The disclosed techniques could prevent mis-detection of OOK symbols caused by cyclic prefix insertion, maintain RF signal transmission at high levels to facilitate better energy harvesting, and enable AIoT devices to track OOK symbol timing even with poor sampling clock accuracy. By designing time domain symbols with consistent beginning and ending portions and / or applying improved cyclic shifting techniques, this disclosure could enable low-complexity AIoT devices to reliably transmit, receive, and decode signals while minimizing power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0050] FIG.1A is an illustration of a subframe of OFDM symbols;

[0051] FIG.1B is an illustration of 2 OOK symbols per OFDM symbol without considering the CP;

[0052] FIG.2A shows an example symbol / basis function (S1) for coded bit 1, in accordance with some implementations;

[0053] FIG.2B shows an example symbol / basis function (S2) for coded bit 0, in accordance with some implementations; FW 6000699PCT03 7

[0054] FIG.2C shows an example symbol / basis function (S1) for coded bit 1, in accordance with some implementations;

[0055] FIG.2D shows an example symbol / basis function (S2) for coded bit 0, in accordance with some implementations;

[0056] FIG.3 illustrates an example procedure to generate M AIoT R2D symbols per OFDM symbol using DFT-S-OFDM, in accordance with some implementations;

[0057] FIG.4 shows an illustration of generating 2 OOK symbols per OFDM symbol using the defined mapping functions defined and the effect of CP insertion;

[0058] FIG.5 shows an illustration of generating 2 OOK symbols per OFDM symbol using the defined mapping functions defined when 9:"is equal or greater than the CP length, in accordance with some implementations;

[0059] FIG.6 illustrates an example procedure of compensating for transition edge timing error due to large sampling period employed, in accordance with some implementations;

[0060] FIG.7 shows PIE encoding as defined in RFID standards;

[0061] FIG.8A shows an example of effective time domain waveform after bit encoding and symbol mapping, in accordance with some implementations;

[0062] FIG.8B shows an example of OFDM-based PIE waveform generation, in accordance with some implementations;

[0063] FIG.9A illustrates an example procedure to generate a PIE signal within the OFDM signal generation framework, in accordance with some implementations;

[0064] FIGs.9B1 and 9B2 show the examples of mapping of data symbols to OOK constant value ON and OFF symbols, in accordance with some implementations;

[0065] FIG.9C illustrates CP insertion process causing OOK symbol timing jump and spurious transition edges for the case of M=4;

[0066] FIG.9D illustrates CP insertion processing causing phase discontinuity in a single OFDM tone;

[0067] FIG.9E illustrates removing jumps in OOK symbol timing and spurious transition edges caused by CP insertion process for the case of M=4 without considering Manchester encoding, in accordance with some implementations;

[0068] FIG.9F shows a flow chart illustrating the modified DFT-s-OFDM signal generation process, in accordance with some implementations;

[0069] FIG.9G shows the eye diagram of the envelope waveform at the receiver without noise;

[0070] FIG.9H shows the eye diagram without the phase compensation; FW 6000699PCT03 8

[0071] FIG.9I illustrates an example of OFDM-based Manchester encoded waveform generation with CP handling for large number of information bits per OFDM symbol, in accordance with some implementations;

[0072] FIG.10A shows a flow chart of a method performed by a wireless device, in accordance with some implementations;

[0073] FIG.10B shows a flow chart of a method performed by a wireless device, in accordance with some implementations;

[0074] FIG.10C shows a flow chart of a method performed by a wireless device, in accordance with some implementations;

[0075] FIG.11 illustrates an example wireless communication system, in accordance with some implementations;

[0076] FIG.12 illustrates an example communication system, in accordance with some implementations;

[0077] FIGs.13A and 14B illustrate example devices, in accordance with some implementations; and

[0078] FIG.14 shows a block diagram of a computing system, in accordance with some implementations.

[0079] Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale. DETAILED DESCRIPTIONS

[0080] For the purpose of co-existence, 3GPP is studying OFDM based waveform for the R2D link. To support low complexity and low power receiver design at the AIoT devices, the OOK waveform is the leading candidate. Within the low power wake-up signal (LP-WUS) study item, two OOK waveforms were defined and are being considered for specification, namely OOK-1, which is defined as 1 OOK symbol per OFDM symbol, and OOK-4, which is defined as M (M>1) OOK symbols per OFDM symbol. OOK-1 can support a data rate the same as the OFDM symbol rate, while OOK-4 can support M times higher data rate than the underlying OFDM symbol rate. For OOK-4, there is a problem of how to handle the cyclic prefix (CP). If the CP is simply ignored, the rest of the OFDM symbol divided up evenly into M OOK symbols, as illustrated in FIGs.1A and 1B, the OOK symbol timing becomes non-uniform. FIG.1A illustrates a subframe of OFDM symbols for numerology ;=0. The 2 green portions of the symbol are identical due to the CP processing. FIG.1B illustrates 2 OOK symbols per OFDM symbol without considering the CP. The CP lengths are exaggerated in FIGs.1A and 1B for the purpose of illustration. As shown in FIGs.1A and 1B, there is a jump in symbol timing whenever a crossing of the OFDM symbol boundaries occur. Moreover, there is a slight additional FW 6000699PCT03 9time jump when crossing the subframe boundaries caused by the slightly longer CP for the first OFDM symbol in each 0.5 ms. To receive such a signal, the AIoT device’s receiver may have to be able to handle this non-uniform OOK symbol timing, resulting in higher complexity and potentially higher power consumption.

[0081] The implementations described in this disclosure aim to solve the above technical challenges and provide other additional benefits to the AIoT R2D link.

[0082] The solutions of this disclosure provide techniques to encode the OOK bit stream in such that the solutions achieve the following technical benefits. • Uniform spacing between encoded bits is achieved regardless of the underlying OFDM symbol numerology, • The CP insertion process does not cause mis-detection of the OOK symbols. • The radio frequency (RF) signal transmission can be kept high for as long as possible to facilitate better RF energy harvesting by the AIoT device from the R2D transmission. • The AIoT device receiver is enabled to track the OOK symbol timing to overcome its poor sampling clock accuracy.

[0083] The implementations for generating OOK waveform define two functions to map encoded data bits into symbols of constant duration 9<<=. The symbol is described by its signal waveform amplitude. FIGs.2A and 2B show mapping functions that map encoded data bits into symbol waveform amplitudes. As shown in FIG.2A, an encoded data bit “1” is mapped to a symbol with a constant high amplitude. As shown in FIG.2B, an encoded data bit “0” is mapped to a symbol with a notched waveform. The notched waveform starts high and stays high for 9?1, transitions to low and stays low for @<<=,then transitions to high and stays high for 9?2, where 9?1 + @<<= + 9?2 = 9<<=. In analternative implementation, the opposite convention can be employed, where the “0” is mapped to a symbol with constant high amplitude and “1” is mapped to a symbol with a notched waveform.

[0084] In some implementations, the mapping functions are defined as shown in FIGs.2C and 2D, which show alternative mapping functions that map encoded data bits into symbol waveform amplitudes. FIG.2C shows that an encoded data bit “0” is mapped to a symbol with a constant low amplitude. FIG.2D shows an encoded data bit “1” is mapped to a symbol waveform that starts low and stays low for 9:^, transitions tohigh and stays high for @^^^, then transitions to low and stays low for 9:", where 9:^ +@^^^ + 9:" = 9^^^. In an alternative implementation, the opposite convention can beemployed, where the “1” is mapped to a symbol with constant low amplitude and “o” ismapped to a symbol with a narrow pulse of duration @^^^within the symbol duration9^^^.FW 6000699PCT03 10

[0085] To map M encoded data bits into M OOK-4 symbols (or basis functions) within an OFDM symbol, the procedure is as shown in FIG.3 and described below.

[0086] For a 5G NR numerology of A=0,1,…, the OFDM symbol length (without CP)is ^FB^CDE^ = 2^GHF, and the cyclic prefix length is^JHF MNOMP^M^ QR, ^PST^F 2 U^V W = 2^^,^ = I9 ∙ 2^LHF + 2^L P^VXYS QR, S = 0 ^V S = 7 ∙ 2F ,which are Ignoring theslightly a length of anOFDM symbol with CP is ^FB^CDE^ + ^F^^,^ = 137 ∙ 2^LHF 9^. At the operation 302 , thisperiod is divided evenly into M AIoT R2D symbol periods, i.e., the symbol period 9^^^= / g * gabcdef / (0,hi .

[0087] Then, at the operation 304, the parameters 9:^, @^^^, 9:" are determined interms of the time unit 9^, and the M encoded data bits per OFDM symbol are mappedinto an amplitude waveform in time domain N^O^, O = 1,2, … 137 ∙ 2^LHF 9^ using themapping functions defined in FIGs.2A-2D above.

[0088] The next operation 306 is to convert the waveform into the appropriate discrete time samples, e.g., down-sampling. First, the OFDM symbol + CP period is / ivided into ^ agbc * / gd def (0,h^^ + ^8+5 sampling periods, each sampling period is / (0* / -23 9^, forexample, if ^ = 144, ^8+5 = 2048, each sampling period is then 2]HFsampling grid, the waveform is converted into N^P^, P = 1,2, … , ^^^ + ^8+5. Out of thetotal ^^^ + ^8+5 discrete time samples, the last ^8+5 samples N^^^, ^ = ^^^ + 1, ^^^ +2, … , ^^^ + ^8+5 are extracted, and then the Discrete Fourier Transform-Spread-OFDM(DFT-s-OFDM) procedure, with proper frequency domain shifting and / or pulse shaping after the DFT operation, is employed to obtain modulation values for the allocated OFDM subcarriers.

[0089] The details of the DFT-s-OFDM procedure can be as following First, at the operation 308, Discrete Fourier Transform (DFT) is used to transform the discrete timesamples into ^m69 frequency domain values n^X^, X = 1,2, … ^8+5. Second, at theoperation 310, pulse shaping or filtering in the frequency domain is applied to n^X^ so that it fits into the allocated OFDM subcarriers. Third, at the operation 312, the signal is combined with other 5G NR signals in the frequency domain, and, at the operation 314, the total signal is converted into the time domain using inverse Fast Fourier Transform (iFFT). Finally, at the operation 316, the cyclic prefix (CP) is added to each OFDM symbol and the resulting time domain signal is upconverted and transmitted. FW 6000699PCT03 11

[0090] The distinction between “1” and “0” waveform is only during the low period of the “0” waveform, which may be called distinct period. To prevent the CP insertion process in OFDM signal generation from impacting this distinction for the first OOK symbol in the OFDM symbol, 9:^can be equal or greater than the CP length, such that the distinct period of the waveform does not overlap with the CP.

[0091] To preserve the two transition edges for each “0”, which is desirable for timing purpose as will be discussed later, 9:"can be greater than 0. The minimum value is determined by the bandwidth allocated for the signal. The smaller the bandwidth, the larger the value. Details of this relationship will be described below.

[0092] FIG.4 illustrates generating 2 OOK symbols per OFDM symbol using the mapping functions defined earlier and the effect of CP insertion. The CP lengths in FIG.4 are exaggerated for illustration purpose. When 9:"is smaller than the CP length, if a “0” happens to be the last symbol in an OFDM symbol, a portion of the notch in its waveform will be repeated at the beginning of the OFDM symbol due to the CP insertion process, creating extra spurious notches in the waveform, as illustrated in FIG.4. However, if the data decoding process in the receiver is based on sampling near the center of the distinct period, the spurious notches in the waveform do not negatively impact the data decoding and can be tolerated.

[0093] FIG.5 illustrates generating 2 OOK symbols per OFDM symbol using the mapping functions defined earlier when 9:"is equal or greater than the CP length, in accordance with some implementations. When 9:"is equal or greater than the CP length, then the CP insertion process does not modify the mapped waveform, because the CP is always at high amplitude, as shown in FIG. 5. However, the tradeoff is the smaller@^^^ = 9^^^ − 2 ∙ ^^^. The width of the notch as a fraction of the OOK symbol period isoppq5ppq = 1 − 2 ∙ / (05ppq = 1 − "i∙ / (0 / (0* / -23 = 1 − 0.131 ∙ ^. M>7 cannot be supported. Table 1value for various values of M.

[0094] Table 1: notch width as a fraction of the OOK symbol period when rst = rsu = vwxM: Number of OOK symbols per OFDM symbol

[0095] If 9:"is allowed to be smaller, for example, let 9:"= / (0, larger M values can be supported, which leads to higher data rate for the system,by Table 2. FW 6000699PCT03 12Table 2: notch width as a fraction of the OOK symbol period when rst = vwx and rsu =vwxz M: Number of OOK symbols per OFDM symbol 23 4 5 6 7 8 9 10sampling. However, when the number of subcarriers allocated for AIoT R2D link is small, computing 2048 point FFT may be an overkill and an inefficient use of resource. They can be scaled down proportionally while remaining integers. The lowest integer values can be ^^^ = 9, ^8+5 = 128, which correspond to a sampling period of 2^LHF 9^.

[0097] As the number of samples per OFDM symbol is decreased, the timing accuracy of converting the mapped (e.g., continuous or high sampling rate) time waveform into a discrete (e.g., lower sampling rate) time waveform suffers. The timing of the transition edges is only accurate to the sampling period. Optionally, if it is necessary to compensate for such an effect without increasing the number of samples per OFDM symbol, a procedure illustrated in FIG.6 and described below can be employed.

[0098] The first operation is to obtain the fraction of time within each sampling period that the mapped (e.g., continuous or high sampling rate) time waveform amplitude is high, {^P^, where P = 1, … , ^^^ + v|}r, then the discrete time amplitudevalues are set to the square root of the fractions obtained ~{^P^. Alternative functions other than square root can also be used.

[0099] The maximum number of independent discrete time samples that can be supported by the allocated bandwidth can be the number of subcarriers contained within the allocated bandwidth. Or the minimum sampling period that can be supported is / 9Bc1^ = agbcdef 9^. Here, ^4^ is the number of OFDM subcarriers used to generate theorder to ensure 2 transitions for each “0”, as mentioned above, 9:"can be greater than 9Bc1^.

[0100] Handling of the slightly longer CP in the first OFDM symbol of a subframe is described below.

[0101] In a normal CP subframe, the regular CP length is 9 ∙ 2^LHF 9^; however, theCP for the first OFDM symbol in the subframe is 9 ∙ 2^LHF + 2^L 9^. The symbol timingerror caused by this is negligible in an AIoT system, where the AIoT device’s sampling clock is not very accurate and the numerology being considered is W = 0 ^V 1.FW 6000699PCT03 13

[0102] In the case when 9:"is not required to be equal to or greater than the regular CP length to avoid spurious notch in the waveform, the signal generation procedure for the first OFDM symbol in a subframe is exactly the same as other OFDM symbols. The slightly longer CP is ignored.

[0103] In the case when 9:"is required to be equal to or greater than the regular CP length to avoid spurious notch in the waveform, for the first OFDM symbol in a subframe, when mapping the last OOK symbol in said OFDM symbol, 9:"can be set to atleast 9 ∙ 2^LHF + 2^L 9^. Correspondingly for that OOK symbol, either 9:^, @^^^ or bothare adjusted accordingly to compensate for the change in 9:".

[0104] Device sampling clock correction based on “0” bits is described below.

[0105] The AIoT device sampling clock can have large error (i.e., poor accuracy) on the order of 105to 104parts per million (ppm). When decoding a message, even when the initial timing can be established accurately through the means of a preamble, the sampling time can quickly drift too far from the ideal sampling time for even a relatively short message. With each “0” bit waveform having two transition edges ensured, the receiver can examine its symbol sample time relative to the two edges whenever a “0” bit is decoded to determine if the symbol sample timing needs to be adjusted for subsequent symbol decoding. This provides a way to maintain good symbol sample timing even with inaccurate sampling clock.

[0106] To ensure that there are no long runs of “1” symbols that could prevent timely correction of the symbol sample timing, scrambling and / or encoding schemes such as Manchester encoding can be used to encode the information bits such that no long runs of “1” symbols would occur.

[0107] In an example implementation, a UE or a device receives an OOK modulated signal over a reader to device (R2D) link.

[0108] The device may, in a first operation, receive configuration information including any of an R2D data rate, a coding scheme, and time domain symbols characteristics.

[0109] In a technical realization, the time domain symbol characteristics may include a mapping from an encoding bit to a time domain symbol, e.g., an information bit 1 to a time domain symbol (S1) and an information bit 0 to a time domain symbol (S2), where S1 and S2 are as defined in e.g., FIGs.2A-2D of this disclosure.

[0110] In another technical realization, the time domain symbol characteristics may include one or more indications of any of a first, a second, and a third time durations of one of the time domain symbols, wherein the first time duration refers to the duration of a high value at the beginning of the symbol, the second time duration refers to the FW 6000699PCT03 14duration of a low value at the middle of the symbol, and the third time duration refers to the duration of the high value at the end of the symbol.

[0111] The device, in a second operation, receives an OOK modulated signal over a physical reader to device channel (PRDCH).

[0112] The device, in a third operation, uses uniformly spaced samples of the received OOK modulated signal to decode one or more encoded bits.

[0113] In a technical realization, a subset of the uniformly spaced samples are selected such that the subset are aligned within the second time duration of at least one of the time domain symbols.

[0114] In another technical realization, the device detects the edges in the received OOK modulated signal. The device may then use the duration between two consecutive (e.g., falling and rising) edges and the second time duration for clock synchronization. In an example, the second time duration may be represented by a first number of samples that should be generated by the device’s clock within the second time duration, then the device may use a second number of samples that are generated by its clock during the duration between the two consecutively detected, e.g., falling and rising, edges for the clock synchronization, i.e., if the first and second numbers are different, then the device may adjust its sample timing depending on the difference.

[0115] Generation of the PIE waveform is described below.

[0116] Pulse interval encoding (PIE) is employed in radio frequency identification (RFID) standards for the reader to device link. In PIE, as illustrated in FIG.7, both data bit “0” and “1” are encoded with a waveform that starts high and then transition to low. The difference between the data bits is in how long the encoded signal stays high. Data bit “1” stays high for much longer time than data bit “0”.

[0117] The technical challenge with implementing the PIE in an OFDM based system is that the symbol period is not a constant, and the symbol period depends on the data bits being encoded, while OFDM symbols have constant duration. However, the waveform described in the section above for generating the OOK waveform can be employed to generate a PIE waveform as illustrated in FIGs.8A and 8B and described below for PIE encoding within the OFDM generation framework. First, data bits are converted into encoded OOK bits by mapping each data bit “1” into OOK bits “10”, and each data bit “0” into OOK bit “0”. Then, the procedure described above with respect to generating the OOK waveform can be used to generate the waveform. Since spurious notches in the waveform are not desirable, in the waveform mapping function, 9:"may be required to be equal to or greater than the CP length. Effectively, for the given example, each data bit “1” is mapped to two OOK symbols, and each Data bit “0” is mapped to 1 OOK symbol, as shown in FIG.8A. However, the duration of the high value FW 6000699PCT03 15can be extended (e.g., lowering the information bit rate) by considering a different encoding scheme where, for example, one or more additional encoded bits of 1 are inserted at the beginning of the codewords for information bits 0 and 1.

[0118] In some example implementations shown in FIG.9A, a gNB or a UE acting as a reader considers PIE for information bit encoding over a reader to device (R2D) link.

[0119] The reader may, in the first step of the first operation 902, encode / map an information bit 1 to a codeword

[0010] and information bit 0 to a codeword [0].

[0120] In another technical realization, the codewords for information bits 1 and 0 may include one or more additional encoded bits of 1 at the beginning of the codewords to support lower information data rate.

[0121] In the second step of the operation 902, the reader generates a first signal by mapping each coded bit to a symbol (e.g., basis function) where a coded bit 1 is mapped to a symbol / function (S1) and a coded bit 0 is mapped to a symbol / function (S2).

[0122] In a technical realization, the two symbols / functions (S1 and S2) can be selected as in FIGs.2A-2D, where it can be noted that the beginning and end of each of symbols / functions are always high and the duration of the high value at the beginning / end can be selected to correspond to at least the cyclic-prefix duration (9^^),i.e., 9:^, 9:" ≥ 9^^. The cyclic-prefix duration (9^^) may be selected to correspond to anyof the short cyclic prefix and the long cyclic prefix of OFDM symbols in a radio subframe. In another technical realization, other two symbols / functions may be selected such that the beginnings and ends of the two symbols are similar.

[0123] In the second operation 904, the reader generates one or more second signals from the first signal wherein each of the one or more second signals correspond to the OFDM symbol duration with cyclic prefix.

[0124] In the third operation 906, the reader generates one or more third signals from the one or more second signals by removing a number of samples corresponding to the cyclic-prefix duration from the beginning of each of the one or more second signals (i.e., from the beginning of the group of symbols / functions in an OFDM symbol.

[0125] In the fourth operation 908, the reader applies DFT to the one or more third signals, allocates the output to one or more subcarriers, and applies iFFT.

[0126] In a technical realization, the reader may apply any of frequency domain modification and filtering on the output of the DFT before allocating to the one or more subcarriers. The fifth step may further comprise multiplexing the DFT output with one or more other new radio (NR) signals / channels.

[0127] In the fifth operation 910, the reader inserts cyclic prefix and transmits the AIoT R2D signal over a physical reader to device channel (PRDCH). The fifth operation 910 may further comprises converting the signal from digital to analog domain, i.e., FW 6000699PCT03 16using an analog to digital converter (ADC), after cyclic prefix insertion. The fifth operation 910 may further comprise upconversion of the signal to an RF frequency.

[0128] An illustration of the first two steps of the operation 902 of the PIE generationprocedure is shown in FIG. 8B, assuming 9:^ = 9:", where the third operation 906combined with the cyclic-prefix insertion, as part of the OFDM generator, can result in the same waveform as in the second step of the operation 902.

[0129] Mapping with constant value OOK symbols is described below.

[0130] In the case where each OOK symbol is defined as having a constant amplitude value of either high (denoted as ON) or low (denoted as OFF) over a constant symbol period of 9^^^:, alternative implementations of this disclosure based on such OOK symbols can be utilized. The data symbol (e.g., information bit, to OOK symbol mappings) is illustrated in FIGs.9B1 and 9B2.

[0131] In one implementation illustrated in FIG. 9B1, a data bit of “1” is mapped intoP5 ON symbols, while a data bit of “0” is mapped into P^ ON symbols, followed by P"OFF symbols, and then P^ ON symbols, where P5 = P^ + P" + P^, and P5,P^, P", P^ arepositive integers. Alternatively, the mapping of data bit “1” and “0” can be swapped.

[0132] In another implementation illustrated by FIG.9B2, a data bit of “0” is mapped into P5OFF symbols, while a data bit of “1” is mapped into P^OFF symbols,followed by P" ON symbols, and then P^ OFF symbols, where P5 = P^ + P" + P^, andP5,P^, P", P^ are positive integers. Alternatively, the mapping of data bit “1” and “0” can beswapped.

[0133] Each OFDM symbol period including the cyclic prefix is an integer multiple of the OOK symbol period. Or, the number of OOK symbols ^ contained in each OFDM symbol period including the cyclic prefix is an integer. Further, ^ is an integer multiple of the number of OOK symbols in each data bit P5. To avoid any spurious transitioncaused by CP insertion in the OFDM signal generation, P^9^^^: ≥ 9^^ and P^9^^^: ≥ 9^^,where 9^^is the length / duration of the cyclic prefix in

[0134] Table 3 shows some example values of ^, P5,P^, P", P^ (assuming P^ = P^) thatavoid spurious transition caused by CP insertion. Table 3 Example values of , ^r,^t, ^u, ^^ (assuming ^t = ^^) that avoid spurioustransition caused by CP insertion. MP9 ^ / P9 P1, P^ P2FW 6000699PCT03 178 4 2 1 2 9 3 3 1 1.

[0136] Besides generating the waveform directly in the time domain then using a DFT to transform it into frequency domain for combining / multiplexing with other NR signals (i.e., through FDM), the waveform can also be generated using frequency domain representation without the need for the DFT operation. The frequency domain response / representation of the time domain waveform can be generated by modifying and superimposing one or more prototype / stored frequency domain responses / representations corresponding to the basis functions illustrated in FIGs.2A- 2D. The one or more prototype / stored frequency domain responses / representations can be modified by applying appropriate linear phase shifts across the frequency domain subcarriers to introduce time delays for the basis functions for proper time domain positioning within the OFDM symbol, i.e., the introduced time delay is an integer multiple of the data symbol, e.g., information bit, duration.

[0137] The procedure for frequency-domain based generation of an OFDM symbol waveform containing M OOK symbols is as follows.

[0138] In a first operation, prototype frequency domain responses / representations for basis functions S1 and S2 are produced. Two types of prototype responses may be generated, one for the first OOK symbol in the OFDM symbol, one for the rest of the OOK symbols in the OFDM symbol. For mapping functions illustrated in FIGs.2C-2D, FW 6000699PCT03 18the two types of prototype responses are the same, but for the mapping functions illustrated in FIGs.2A-2B, they are different. This first operation comprises of the following.

[0139] (a) A continuous time domain waveform of length equal to an OFDM symbol duration plus cyclic prefix is generated. For the first type, or the first OOK symbol in an OFDM symbol, one S1 or S2 function is set at the position of the first OOK symbol, and the value for the rest of the time is set to zero. For the second type, or the rest of OOK symbols in an OFDM symbol, one of S1 or S2 function is at the position of the second OOK symbol, and the value for the rest of the time is set to zero.

[0140] (b) The waveform to a length equal to an OFDM symbol duration is truncated by removing a beginning portion of the waveform equal to the length of the cyclic prefix.

[0141] (c) The waveform is sampled into uniform discrete time samples. The number of time samples is equal to the desired DFT size ^8+5, or the number of subcarriers used to encode the signal.

[0142] (d) Optionally, the discrete time samples are modulated using a modulus 1 complex sequence. An example sequence is a Zadoff-Chu sequence, or a bipolar m- sequence.

[0143] (e) The waveform is transformed into frequency domain using DFT to obtain the prototype frequency domain response / representation for basis function S1 or S2.

[0144] Any of the elements under this first operation can be applied in a different order, for example, elements (b) and (c) can be exchanged.

[0145] In a second operation, for each data symbol ^ within the OFDM symbol,where ^ ∈ 0,1, … , ^ − 1, the corresponding prototype frequency domain response (e.g.,data symbol value “1” corresponds to S1, “0” to S2) can be taken, a linear phase shift can be applied across subcarriers to obtain the proper frequency domain response of the ^^^OOK symbol accounting for its order within the OFDM symbol.

[0146] For ^ = 0, the corresponding frequency domain response is of the first type,and there is no need to apply any phase shift.

[0147] For ^ > 0, the corresponding frequency domain response is of the secondtype. The phase shift is calculated using the following equation: ^^^, S^ = "#^^^H^^i , whereS ∈ 0,1, … , ^8+5 − 1 is the index to the subcarriers.

[0148] In a third operation, the sum of all the modified frequency domain responses / representations corresponding to the data symbols within the OFDM symbol is used to produce the overall frequency domain response / representation of the OFDM symbol.

[0149] CP handling for high data rate OOK waveform is described below. FW 6000699PCT03 19

[0150] The implementations described above mainly addressed the case when a low data rate waveform is considered. For high data rate OOK waveform, alternative implementations can combine transmitter and receiver operation(s).

[0151] In this case, the mapping between information bits and chips can be utilized as opposed to the section above with respect to mapping with constant value OOK symbols (e.g., for Manchester encoding). An information bit 1 is mapped to chips {01} and information bit 0 is mapped to chips {10}.

[0152] Further, ^ chips with equal durations 9^^^:within the OFDM symbol, notincluding the cyclic prefix (CP) duration (i.e., 9^^^: = 9B^C / ^ where 9B^C is the durationof the OFDM symbol without CP) can be considered. Chip skipping pattern at the device side can be considered. Additionally, a design based on modulus operations and linear increasing cyclic shift of the ^ chips’ samples, per OFDM symbol, with OFDM symbol index can be considered.

[0153] For subcarrier spacing of 15 kHz, using an iFFT size of NiFFT=2048, the length of the CP is NCP=144 samples, except for the first OFDM symbol in a slot and subsequently every 7thOFDM symbol, for which the CP length is slightly longer at NCP=160 samples.

[0154] To generate ideal OOK waveforms with constant OOK symbol timing and no spurious transition edges, several technical issues are to be overcome. The issues are listed below and illustrated in FIGs.9C and 9D for the case of M=4. 1. The CP insertion introduces a timing jump between OOK symbols in 2 consecutive OFDM symbols. This disrupts the constant timing expected of an ideal OOK waveform. 2. The CP insertion introduces undesirable or spurious additional transition edges that the detector has to account for when demodulating the signal. 3. The CP insertion introduces phase discontinuity in the RF carrier between consecutive OFDM symbols, causing a dip in the RF envelope of an OOK ON pulse that straddles the OFDM symbol boundary.

[0155] This disclosure solves these technical issues through the following technical solutions, as illustrated in FIG.9E for the case of M=4.

[0156] 1. Cyclic shifting (or circular shifting) of the time domain waveform by a specific amount for each OFDM symbol before the DFT operation is carried out to adjust the OOK symbol boundaries or information bit (when Manchester encoding is employed) boundaries. The purpose is to remove the timing jump in OOK symbol timing introduced by CP insertion. This operation achieves a constant OOK symbol timing.

[0157] 2. The last OOK chip or information bit (when Manchester encoding is employed) in an OFDM symbol may not be complete due to the cyclic shifting. To ensure FW 6000699PCT03 20continuity, in the following OFDM symbol, an OOK chip or information bit is forced to the same value as (or repeats) the incomplete OOK chip or information at the end of the previous OFDM symbol. In FIG.9E, this chip repeating is illustrated by OOK chips with the same pattern. The index of the repeating OOK chip or information bit is determined by the amount of cyclic shift of the current OFDM symbol, the OOK symbol length, and the CP length. This operation prevents any transition edge from occurring at a location other than an OOK symbol boundary.

[0158] 3. A phase compensation is applied to each OFDM symbol to ensure RF carrier phase continuity. This may be a single phase rotation applied to all the R2D subcarriers in each OFDM symbol. The value of the phase rotation depends on the value applied to the previous OFDM symbol, the length of the CP of the current OFDM symbol, and the location of the center of the R2D spectrum in the large carrier. This operation removes any dip in the RF envelope of an OOK ON pulse that straddles the OFDM symbol boundary.

[0159] FIG.9F is a flow chart illustrating details of the modified DFT-s-OFDM signal generation process described above, in accordance with some implementations.

[0160] At the operation 921, the information bits are assembled to be transmitted per OFDM symbol, taking into account any bit that needs to be inserted and take on the same value as a bit in a previous OFDM symbol. Information assembled for this operation can be read from a lookup table (LUT). A detailed algorithm to calculate the LUT is described later in the document.

[0161] At the operation 922, Manchester encoding is applied to the information bits to obtain OOK chip values per OFDM symbol.

[0162] At the operation 923, a time domain waveform of NDFTsamples is generated based on the OOK chip values per OFDM symbol.

[0163] At the operation 924, the time domain waveform is cyclic shifted by a specific number of samples. The number of sample shifts per OFDM symbol is not dependent on data and can be read from a LUT. A detailed algorithm to calculate the LUT is described below in this disclosure.

[0164] At the operation 925, the waveform is transformed into the frequency domain using an NDFT point DFT to obtain NDFT complex modulation values for NDFT OFDM sub- carriers.

[0165] At the operation 926, an FFT shift operation is carried out to center the frequency spectrum in the middle of the NDFT subcarriers.

[0166] At the operation 927, the spectrum is truncated to leave only NSC(<NDFT) subcarriers in the center, where NSC is the number of subcarriers allocated for the R2D transmission. FW 6000699PCT03 21

[0167] At the operation 928, a phase rotation is applied to the NSC subcarrier modulation values. A detailed algorithm to calculate the phase rotation amount is described later in the disclosure.

[0168] At the operation 929, the NSC subcarriers are placed into a larger carrier with NiFFTsubcarriers starting at an index of FR2D∈{0,1,2,…, NiFFT-NSC}.

[0169] At the operation 930, an iFFT is performed on the full carrier of NiFFTsubcarriers to produce NiFFTtime sample waveform.

[0170] At the operation 931, NCP samples of the waveform from the end are copied and added to the beginning of the waveform.

[0171] FIGs.9G and 9H show the result time domain waveform at the receiver after band-limiting and envelope detection without noise in the form of an eye diagram. FIG. 9G shows the result for M=32, NiFFT=2048, NDFT= 384, NSC=144. The reason a value of 384 is chosen for NDFT is because it is the smallest number that can be evenly divided by all the supported M values while maintaining the length of the CP as an integer. This avoids fractional cyclic shift at the operation 924. This value can be further reduced if only M values of power of 2 are supported. FIG.9H shows the result when the operation 928 is bypassed. The phase compensation can help solve the occasional dips in the envelope waveform shown in FIG.9H.

[0172] At the receiver, after envelope detection, the OOK stream with Manchester encoding is decoded into an information bit stream. The repeated bits are then discarded or skipped. For the candidate M values (4, 8, 12, 16, 24, 32), 7 consecutive OFDM symbols contain exactly an integer number of OOK chips or information bits, therefore the pattern for discarding or skipping bits is periodic with a period of 7 OFDM symbols. For M=6, 14 consecutive OFDM symbols are used to fit an integer number of information bits with Manchester encoding. Therefore, its pattern is periodic with a period of 14 OFDM symbols. Table 4 shows the number of information bits that can fit into 7 consecutive OFDM symbol period, the number of information bits expected based on the M value, the number of information bits actually carried after discarding the repeated bits, and an efficiency number for all supported M values, assuming Manchester encoding is employed. The efficiency is calculated as the ratio between the number of bits actually carried and the number of bits expected based on M value. Table 4. Efficiency for supported M values M Value # of bits that fit # of bits # of bits EfficiencyFW 6000699PCT03 228 30 28 22 79% 12 45 42 36 86%supported M values. In the tables below, 0 represents a bit to keep, while 1 presents a bit to skip. The number of columns in the tables are chosen so as to show the pattern more clearly. Table 5. Bit skipping pattern for M=32. It repeats after 120 bits. (read row wise) Bit Index 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1a e . s ppng pa ern or . repeas a er s. rea row wse Bit Index 1 2 3 4 5 6 7 8 9 10 11 12 13 1 1 1 1 1 1Table 7. Bit skipping pattern for M=16. It repeats after 60 bits. (read row wise) Bit Index 1 2 3 4 5 6 7 8 9 1 1FW 6000699PCT03 230 0 0 0 0 0 0 1 0 Bit 0 0 0 0 0 0 1 1 0 0 0 Table 8. Bead row wise) Bit Index 1 2 3 4 5 6 7 0 0 0 0 0 0 1 0 0 0 0 0 Table 9. Bit sk. s. (read row wise) Bit Index 1 2 3 4 5 1 0 0 0 0 1 Table 10. Bit skipping pattern for M=6. It repeats after 45 bits. (read row wise) Bit Index 1 2 3 4 5 6 7 1 0 0 0 0 1FW 6000699PCT03 24Table 11. Bit skipping pattern for M=4. It repeats after 15 bits. (read row wise) Bit Index 1 2 3 0 0 1 0 1 0 1

[0174] The purpose of thM symbol of the message is to align the OOK symbol boundary with the beginning of the CP. For subsequent OFDM symbols, the cyclic shift needs to align the OOK symbol boundary with the OOK symbol boundaries in the previous OFDM symbol. The formula for calculating the amount of cyclic shift is the following, assuming Manchester encoding is applied (note the cyclic shift is assumed to be shifting to the left): ^^^^^^^^^^^ = ^^^ ^^ ^^^^^^ , 2^^^^^^^^where ^ = 1,2, … is ^^^^^^ is the CPlength as the number of DFT samples for the ^th OFDM symbol in the message, ^^^^isthe length of each OOK symbol as number of DFT samples, and ^^^^ ^ is the modulooperation.

[0175] Since the CP length is not the same for all the symbols, even though ^^^^^^^^^^is periodic with a period of 7 OFDM symbols for M=4,8,12,16, 24 and 32, and 14 for M=6, the actual values depends on where the first OFDM symbol in the message starts in relation to the OFDM symbol with slightly longer CP. Table 12 shows the cyclic shift values for M=32 for different starting position of the first OFDM symbol of the message. In the table, starting index of 1 means that the message starts with an OFDM symbol with slightly longer CP. The 7thOFDM symbol’s cyclic shift is always 0, because even number of information bits fit exactly into 7 OFDM symbols regardless of where the message starts in relation to the OFDM symbol with slightly longer CP. Table 12. Cyclic shift values for each OFDM symbol in a message for M=32 and NDFT= 384 Starting 7 3 9FW 6000699PCT03 25(number 12 9 9 9 9 12 12 of DFT 15 12 12 12 15 15 15 8 1

[0176] Since theation bit, the incomplete last bit in the OFDM symbol after cyclic shift is always the first bit. The following OFDM symbol’s CP has to continue this incomplete bit by repeating it in one of its bits. The index to the repeating bit is calculated using the following formula: ^^^^^^^ − ^^^^ ^^^= ^:^^^^ ^ ^^^^ ^ =2 − ^2^ ^^^^where ^ = 1,2, … is the and ^ ^ is the flooroperation.

[0177] If the last bit in the previous OFDM symbol is complete, then there is no need to repeat in the current OFDM symbol. This is represented by an index of 0 in the following table 13 which lists the bit repeating pattern for all supported M values. For all the supported M values, the bit repeating pattern is periodic with a 7 (14 for M=6) OFDM symbol period. Table 13. Repeating bit index in each OFDM symbol for all the supported M values. M Value 4 6 8 12 16 24 32FW 6000699PCT03 263

[0178] The forapplied to each OFDM symbol in the message is the following: "#∙%&'( *+,)-*^.∙ / ( ^^^^^1^ = 0, ^^^^ = ^^^ − 1^ + ) 0 / 1223where ^ = 2,3, …

[0179] Onceto determine the redundant bits in the message that need to be skipped by the receiver.

[0180] Let ^8+5be the DFT size, 9B,:^^be the pre-DFT sample time, ^B^Cbe thenumber of OFDM symbols used in the R2D transmission, ^^^^E,^ be the vector of ^^ =^ / 2 information bits in the ^^^ OFDM symbol, and ^^^^:,^ be the vector of ^ Manchesterencoded chips from ^^^^E,^ in the ^^^ OFDM symbol, where ^ ∈ ^1, 2, … , ^B^C^. The vectorof encoded chips ^^^^:,^is obtained here by Manchester encoding the ^′ information bits in ^^^^E,^; however, different encoding scheme for which the number of information bits in ^^^^E,^may not necessarily be equal to M / 2 may be considered. Then, the overall procedure for Manchester encoded R2D signal generation with CP handling can be described as follows.

[0181] In a first operation, a minimum circular shift value can be set in one technicalrealization as below.^B^^^^,C^^ = ^^^ − ^^^^:, where ^^^^: = 9^^^: / 9B,:^^

[0182] In another technical realization, the minimum circular shift can be set as below. ^^^ = / (0B^^^^,C ^^^ − ^^^^: or ^B^^^^,C^^ = X^^^^^^, ^^^^:^

[0183] shiftat the ^^^ OFDM symbol can be defined in one technical realization as below.^B^^^^,^ = X^^^^ × ^B^^^^,C^^, ^^^^:^, ^ ∈ ^1, 2, … , ^B^C^

[0184] In a second technical realization, in which the CP may be changing from one OFDM symbol to the other, the incrementing circular shift at the ^^^OFDM symbol can be defined as below. ^ where ^^^,BisOFDM symbol. FW 6000699PCT03 27

[0185] In a third technical realization, the incrementing circular shift at the ^^^OFDM symbol can be defined as below.^B^^^^,^ = ^^^ − X^^^−^^ − 1^ × ^^^, ^^^^:^, ^ ∈ ^1, 2, … , ^B^C^

[0186] In a third operation, the value of the T^*^ chip in the ^^ + 1^^^ OFDM symbolmay be set to be the same as the value of the N^ chip in the ^^^ OFDM symbol whereN^, T^*^ ∈ {1, 2, … , ^} are the chip index in ^^^^:,^ , ^^^^:,^*^, respectively, which can beobtained in a first technical realization as below. ^N^ = X^^ ^^ 8+5 + ^B^^^^,^^ ^ , ^^ + 1, ^ ∈ ^1, 2, … , ^B^C − 1^^^^:1^N^… , −N^ = 1,T^*^ = ^ − ^ ^^^^ ^,^^^:where the values of the N^^^ and T^^^*^ chips may be set the same only if ^B^^^^,^ ≠ 0.

[0188] In a third technical realization, the chip indices N^ and T^*^ ∀^ ∈^1, 2, … , ^B^C − 1^ can be set as below.^N^ = ^ ^^^ ^ + 1,

[0189] In case an information bit is encoded using multiple chips (e.g., Manchester encoding), the values of the two chips can be set to the same by setting the values of the two information bits that contain the two chips appropriately. For the case of Manchester encoding, the values of the two chips may be set to be the same by setting the values of the corresponding information bits in ^^^^E,^and ^^^^E,^*^to be the same or differentdepending on whether the N^ , T^*^ chips correspond to the same or different chips withinthe Manchester code representing the corresponding information bits. For example, ifX^^^N^, 2^ = X^^^T^*^, 2^, then ^^^^E,^*^¨^^T^*^ − 1^ / 2^ + 1© = ^^^^E,^¨^^N^ − 1^ / 2^ + 1©,FW 6000699PCT03 28

[0190] In a fourth operation, the ^^^^:,^vector is up-sampled by ^^^^:to obtain ^°^^^:,^for the ^^^OFDM symbol and the derived cycle shift ^B^^^^,^is applied to obtain ±°^^^:,^asbelow.±°^^^:,^¨_© = ^°^^^:,^²^_ + ^B^^^^,^^ X^^ ^ × ^^^^:³

[0191] DFT iFFT, and cyclic-prefix insertionthe waveform at the^^^ OFDM symbol.

[0192] Alternatively, the up-sampled vector ^°^^^:,^for the ^^^OFDM symbol is applied directly to the DFT module and the cyclic shift is implemented as a linear phase shift in the frequency domain after the DFT operation and before the iFFT operation.

[0193] At the device side, in a first embodiment, the device may be required to skip one or more chips every (e.g., ^, chips with a known pattern). In a technical realization, the minimum number of chips ^B^^:,C^^to be skipped by the device every, e.g., ^, chipscan be determined as below.^B^^:,C^^ = ´^^^ / ^^^^:µ

[0194] An additional chip on the accumulation ofcyclically shifted samples across an additional chip may be skipped if the following condition is satisfied. ^× ^B^^^^,C ^^ − 1^ × ^ ^^ ^^ ^ − ^ B^^^^,C^^ ^ > B^^^^,C^^^ ^ 9^¶^, 9^¶^ ∈ ·0, ^^ ^¸

[0195] if thefollowing condition is satisfied. ∑^ ^H^^ B^^ ^^^,B ∑^ − ^ B^^ ^^^,B^ ^ > 9^¶^where 9^¶^ may be set to

[0196] In a second implementation, in case an information bit is encoded using multiple chips (e.g., Manchester encoding), the device may be required to skip one or multiple information bits. In this case, any information bit that contains at least one chip that is to be skipped as described in the first embodiment is to be skipped. This implementation can preserve the uniform timing of the information bits in the transmission.

[0197] An illustration of a generated Manchester encoded R2D signal with ^ = 16chips per OFDM symbol for 4 OFDM symbols is shown in FIG.9C, along with the chips that needs to be skipped by the device. In the example, the device only sees chips with consistent / fixed duration as well as fixed spacing between the OOK chips. Further, with FW 6000699PCT03 29the proper (i.e., according to a specific / known pattern) skipping of extra chip(s), there will be no false rising or falling edges because of the CP insertion of the OFDM generator at the transmitter side.

[0198] In an implementation, the transmitter / reader may select a data transmission rate based on the device capability, i.e., chip skipping with known pattern. In a first operation, the reader may transmit a first message for capability poll using a low data rate. In a second operation, the reader receives a chip skipping capability indication from one or more devices. In a third step, the reader transmits one or more second messages to the one or more devices using a high data rate. In an alternative to the second operation, the reader receives one or more messages indicating chip skipping is not supported from one or more devices. Subsequently, the reader transmits one or more second messages to the one or more devices using a low data rate.

[0199] In another implementation, a device receives in a first operation a capability poll message using a low data rate. In a second operation, the device transmits an indication of support for high data rate and / or chip skipping capability. In a third operation, the device receives a second message using high data rate. In a fourth operation, the device decodes the second message by skipping one or more chip(s) every M chips and discarding one or more information bit(s) every ^′ information bits after the first ^′ information bits. In a technical realization, the number of the one or more chip(s) and the one or more information bit(s) to be skipped / discarded are received in any of a configuration message and a preamble preceding the high data rate message. In another technical realization, the device determines the number of the one or more chip(s) and the one or more information bit(s) to be skipped / discarded based on any of a value M of the number of chips per OFDM symbol, a data rate indication, a subcarrier spacing, and an OFDM symbol duration.

[0200] FIG.10A shows a flow chart of a method 1000 performed by a wireless device (e.g., a wireless transmit / receive unit (WTRU)), in accordance with some implementations. The wireless device may include computer-readable code or instructions executing on one or more processors of the wireless device. Coding of the software for carrying out or performing the method 1000 is well within the scope of a person of ordinary skill in the art having regard to the present disclosure. The method 1000 may include additional or fewer operations than those shown and described and may be carried out or performed in a different order. Computer-readable code or instructions of the software executable by the one or more processors may be stored on at least one non-transitory computer-readable medium, such as for example, at least one memory of the wireless device. In some embodiments, the method 1000 may be performed by one or more of units or modules (e.g., an integrated circuit) of the wireless FW 6000699PCT03 30device, such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0201] The method 1000 starts at the operation 1002, where the wireless device generates a first signal by mapping a first encoded bit to a first time domain symbol and a second encoded bit to a second time domain symbol. The first signal includes the first time domain symbol and the second time domain symbol. The first encoded bit is 1, and the second encoded bit is 0. A first beginning portion of the first time domain symbol, a first ending portion of the first time domain symbol, a second beginning portion of the second time domain symbol, and a second ending portion of the second time domain symbol are the same. At the operation 1004, the wireless device generates an orthogonal frequency division multiplexed (OFDM) symbol including a cyclic prefix (CP) based on the first signal. At the operation 1006, the wireless device transmits the OFDM symbol.

[0202] In some implementations, the wireless device may encode a first information bit and a second information bit into a plurality of encoded bits including the first encoded bit and the second encoded bit. The first information bit may be 1, and the second information bit may be 0. Or, the first information bit may be 0, and the second information bit may be 1.

[0203] In some implementations, the first information bit may be encoded into a first codeword comprising two encoded bits [1, 0], and the second information bit may be encoded into a second codeword comprising one encoded bit [0].

[0204] In some implementations, the first codeword and the second codeword may each further comprise one or more additional encoded bits of 1 at a first beginning of the first codeword and a second beginning of the second codeword.

[0205] In some implementations, the first information bit and the second information bit may be encoded into a first codeword and a second codeword based on Manchester encoding.

[0206] In some implementations, the first encoded bit and the second encoded bit may be the same as the first information bit and the second information bit, respectively.

[0207] In some implementations, symbol durations of the first time domain symbol and the second time domain symbol may be the same.

[0208] In some implementations, the first time domain symbol may be a constant high value over a first symbol duration of the first time domain symbol. The second time domain symbol may include a first transition from the constant high value to a constant low value after a first duration corresponding to the second beginning portion of the second time domain symbol. The second time domain symbol may further include a second transition from the constant low value to the constant high value starting at a FW 6000699PCT03 31second duration corresponding to the second end portion of the second time domain symbol.

[0209] In some implementations, the first information bit may be encoded into a first codeword comprising two encoded bits [0, 1]. The second information bit may be encoded into a second codeword comprising one encoded bit [1], respectively.

[0210] In some implementations, the first codeword and the second codeword may each further comprise one or more additional encoded bits of 0 at a first beginning of the first codeword and a second beginning of the second codeword.

[0211] In some implementations, the second time domain symbol may be a constant high value over a second symbol duration of the second time domain symbol. The first time domain symbol may include a first transition from the constant high value to a constant low value after a first duration corresponding to the first beginning portion of the first time domain symbol. The first time domain symbol may further include a second transition from the constant low value to the constant high value starting at a second duration corresponding to the second end portion of the first time domain symbol.

[0212] In some implementations, the first duration and the second duration may be selected to correspond to at least a duration of the CP in the OFDM symbol.

[0213] In some implementations, numbers of the one or more additional encoded bits for the first codeword and the second codeword may be the same.

[0214] In some implementations, numbers of the one or more additional encoded bits for the first codeword and the second codeword may be different.

[0215] In some implementations, to generate the OFDM symbol, the wireless device may generate one or more second signals from the first signal. Each of the one or more second signals may have a duration corresponding to an OFDM symbol duration of the OFDM symbol including the cyclic prefix. The wireless device may generate one or more third signals from the one or more second signals by removing a number of samples corresponding to a CP duration from a corresponding beginning of each of the one or more second signals. The wireless device may generate a frequency domain representation of the one or more third signals. The wireless device may apply the frequency domain representation to one or more subcarriers of an OFDM generator function.

[0216] In some implementations, generating the frequency domain representation is based on at least one of a discrete Fourier transform (DFT) operation or mapping from one of the one or more third signals to one or more pre-stored or pre-generated frequency domain representations.

[0217] In some implementations, the one or more third signals may be further modified to reverse an operation of OFDM symbol windowing. FW 6000699PCT03 32

[0218] In some implementations, the OFDM generator function may comprise at least one of inverse fast Fourier transform (iFFT) operation, CP insertion, digital-to- analog conversion (DAC), or frequency domain upconversion.

[0219] In some implementations, the frequency domain representation may be any of a modified representation or a filtered representation before the applying the frequency domain representation to the one or more subcarriers.

[0220] In some implementations, to transmit the OFMD symbol, the wireless device may transmit the OFDM symbol including the CP over a physical reader to device channel (PRDCH).

[0221] FIG.10B shows a flow chart of a method 1030 performed by a wireless device (e.g., a wireless transmit / receive unit (WTRU)), in accordance with some implementations. The wireless device may include computer-readable code or instructions executing on one or more processors of the wireless device. Coding of the software for carrying out or performing the method 1030 is well within the scope of a person of ordinary skill in the art having regard to the present disclosure. The method 1030 may include additional or fewer operations than those shown and described and may be carried out or performed in a different order. Computer-readable code or instructions of the software executable by the one or more processors may be stored on at least one non-transitory computer-readable medium, such as for example, at least one memory of the wireless device. In some embodiments, the method 1030 may be performed by one or more of units or modules (e.g., an integrated circuit) of the wireless device, such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0222] The method 1030 starts at the operation 1032, where the wireless device assembles respective information bits for each orthogonal frequency division multiplexed (OFDM) symbol based on information bits in a message for a plurality of OFDM symbols to generate assembled information bits for each OFDM symbol. At the operation 1034, the wireless device generates a time domain waveform for each OFDM symbol based on the assembled information bits for each OFDM symbol. At the operation 1036, the wireless device cyclic shifts the time domain waveform for each OFDM symbol. After the cyclic shifting, at the operation 1038, the wireless device transforms the time domain waveform for each OFDM symbol to generate complex modulation values for each OFDM symbol. At the operation 1040, the wireless device generates subcarrier modulation values based on the complex modulation values. At the operation 1042, the wireless device applies a phase rotation to the subcarrier modulation values.

[0223] In some implementations, to assemble the respective information bits, the wireless device may determine a repeating or redundant bit index for an OFDM symbol FW 6000699PCT03 33based on a cyclic shift value of a previous OFDM symbol. The wireless device may insert a repeating or redundant bit at a bit position based on the repeating or redundant bit index in the OFDM symbol. The repeating or redundant bit may have a same value as an incomplete bit of the previous OFDM symbol.

[0224] In some implementations, to assemble the respective information bits, the wireless device may determine a repeating or redundant bit index for an OFDM symbol based on a repeating or redundant bit index lookup table, a number of On-Off Keying (OOK) symbols per OFDM symbol, and a position of the OFDM symbol in the message. The wireless device may insert a repeating or redundant bit at a bit position based on the repeating or redundant bit index in the OFDM symbol. The repeating or redundant bit may have a same value as an incomplete bit at an end of a previous OFDM symbol.

[0225] In some implementations, to cyclic shift the time domain waveform for each OFDM symbol, the wireless device may determine a cyclic shift value for an OFDM symbol in the message based on cyclic prefix (CP) lengths of previous OFDM symbols in the message, a CP length of the OFDM symbol, and a length of each OOK symbol in number of discrete Fourier transform (DFT) samples.

[0226] In some implementations, the cyclic shift value for the OFDM symbol in the message may be based on the following. ^^^^^^^^^^^ = ^^^ ^^ ^^^^^^ , 2^^^^^^^^

[0227] ^^^^^^^^^^ may may an index to a k-th OFDM symbol in the message. ^^^^^^may be the CP length of an i-th OFDM symbol in the message in number of DFT samples. ^^^^may be the length of each OOK symbol in number of DFT samples.

[0228] In some implementations, to cyclic shift the time domain waveform for each OFDM symbol, the wireless device may determine a cyclic shift value for an OFDM symbol based on a cyclic shift value lookup table, a number of On-Off Keying (OOK) symbols per OFDM symbol, and a position of the OFDM symbol in the message.

[0229] In some implementations, to apply the phase rotation, the wireless device may determine a phase rotation value for an OFDM symbol in the message based on a previous phase rotation value of a previous OFDM symbol, a CP length of the OFDM symbol, a starting frequency index, a number of subcarriers, and a Fast Fourier Transform (iFFT) size.

[0230] In some implementations, the phase rotation value may be based on the following. FW 6000699PCT03 34"#∙%&'( *+ *^.∙ / ^ ^^ 1^ = 0, ^^^^ = ^^^ − 1^ + ,)- ^^ ) (0 / 1223

[0231] ^^^^ may be the phaseto a k-th OFDM symbol in the message. ^4^may be the number of subcarriers allocated for transmitting the message, ^^^^^^is the CP length of the k-th OFDM symbol. ^^++5may be the iFFT size, and 67"8∈{0,1,2,…, NiFFT-NSC}.

[0232] FIG.10C shows a flow chart of a method 1060 performed by a wireless transmit / receive unit (wireless device), in accordance with some implementations. The wireless device may include computer-readable code or instructions executing on one or more processors of the wireless device. Coding of the software for carrying out or performing the method 1060 is well within the scope of a person of ordinary skill in the art having regard to the present disclosure. The method 1060 may include additional or fewer operations than those shown and described and may be carried out or performed in a different order. Computer-readable code or instructions of the software executable by the one or more processors may be stored on at least one non-transitory computer- readable medium, such as for example, at least one memory of the wireless device. In some embodiments, the method 1060 may be performed by one or more of units or modules (e.g., an integrated circuit) of the wireless device, such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0233] The method 1060 starts at the operation 1062, where the wireless device receives a second message using a second data rate. The second message comprises a first set of bits. At the operation 1064, the wireless device determines a second set of bits by discarding one or more bits in the first set of bits.

[0234] In some implementations, the first data rate may be a low data rate that does not require additional handling capability. The second data rate may be a high data rate that requires the additional handling capability at the wireless device.

[0235] In some implementations, the first set of bits may be a set of Manchester encoded bits or chips.

[0236] In some implementations, the wireless device may determine a third set of bits by skipping one or more chips every M chips in the first set of bits. M is a number of On-Off keying (OOK) chips per OFDM symbol. The wireless device may decode a fourth set of bits from the third set of bits based on Manchester encoding. The wireless device may determine the second set of bits by discarding one or more bits in the fourth set of bits. FW 6000699PCT03 35

[0237] In some implementations, a number of the one or more chips or bits to be skipped or discarded may be received in one of a configuration message or a preamble preceding the second message.

[0238] In some implementations, a number of the one or more chips or bits to be skipped or discarded may be determined based on any of M, a data rate indication, a subcarrier spacing, or an OFDM symbol duration.

[0239] In some implementations, any of the first set of bits or the second set of bits may include encoded chips or information bits.

[0240] The following references are incorporated herein by reference in their entireties. [1] 3GPP RP-234058, New SID: Study on solutions for Ambient IoT (Internet of Things) in NR, Huawei, Dec 2023. [2] 3GPP TR 38.848, Study on Ambient IoT (Internet of Things) in RAN, Release 18, 2023.

[0241] FIG.11 illustrates an example communications system 1100. Communications system 1100 includes an access node 1110 serving user equipments (UEs) with coverage 1101, such as UEs 1120. In a first operating mode, communications to and from a UE passes through access node 1110 with a coverage area 1101. The access node 1110 is connected to a backhaul network 1115 for connecting to the internet, operations and management, and so forth. In a second operating mode, communications to and from a UE do not pass through access node 1110, however, access node 1110 typically allocates resources used by the UE to communicate when specific conditions are met. Communications between a pair of UEs 1120 can use a sidelink connection (shown as two separate one-way connections 1125). In FIG.11, the sidelink communication is occurring between two UEs operating inside of coverage area 1101. However, sidelink communications, in general, can occur when UEs 1120 are both outside coverage area 1101, both inside coverage area 1101, or one inside and the other outside coverage area 1101. Communication between a UE and access node pair occur over uni-directional communication links, where the communication links between the UE and the access node are referred to as uplinks 1130, and the communication links between the access node and UE is referred to as downlinks 1135.

[0242] Access nodes may also be commonly referred to as Node Bs, evolved Node Bs (eNBs), next generation (NG) Node Bs (gNBs), master eNBs (MeNBs), secondary eNBs (SeNBs), master gNBs (MgNBs), secondary gNBs (SgNBs), network controllers, control nodes, base stations, access points, transmission points (TPs), transmission-reception points (TRPs), cells, carriers, macro cells, femtocells, pico cells, and so on, while UEs may also be commonly referred to as mobile stations, mobiles, terminals, users, FW 6000699PCT03 36subscribers, stations, and the like. Access nodes may provide wireless access in accordance with one or more wireless communication protocols, e.g., the Third Generation Partnership Project (3GPP) long term evolution (LTE), LTE advanced (LTE- A), 5G, 5G LTE, 5G NR, sixth generation (6G), High Speed Packet Access (HSPA), the IEEE 802.11 family of standards, such as 802.11a / b / g / n / ac / ad / ax / ay / be, etc. While it is understood that communications systems may employ multiple access nodes capable of communicating with a number of UEs, only one access node and two UEs are illustrated for simplicity.

[0243] FIG.12 illustrates an example communication system 1200. In general, the system 1200 enables multiple wireless or wired users to transmit and receive data and other content. The system 1200 may implement one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), or non-orthogonal multiple access (NOMA).

[0244] In this example, the communication system 1200 includes electronic devices (ED) 1210a-1210c, radio access networks (RANs) 1220a-1220b, a core network 1230, a public switched telephone network (PSTN) 1240, the Internet 1250, and other networks 1260. While certain numbers of these components or elements are shown in FIG.12, any number of these components or elements may be included in the system 1200.

[0245] The EDs 1210a-1210c are configured to operate or communicate in the system 1200. For example, the EDs 1210a-1210c are configured to transmit or receive via wireless or wired communication channels. Each ED 1210a-1210c represents any suitable end user device and may include such devices (or may be referred to) as a user equipment or device (UE), wireless transmit or receive unit (wireless device), mobile station, fixed or mobile subscriber unit, cellular telephone, personal digital assistant (PDA), smartphone, laptop, computer, touchpad, wireless sensor, AIoT device (e.g., for asset management), or consumer electronics device.

[0246] The RANs 1220a-1220b here include base stations 1270a-1270b, respectively. Each base station 1270a-1270b is configured to wirelessly interface with one or more of the EDs 1210a-1210c to enable access to the core network 1230, the PSTN 1240, the Internet 1250, or the other networks 1260. For example, the base stations 1270a-1270b may include (or be) one or more of several well-known devices, such as a base transceiver station (BTS), a Node-B (NodeB), an evolved NodeB (eNB), a Next Generation (NG) NodeB (gNB), a gNB centralized unit (gNB-CU), a gNB distributed unit (gNB-DU), a Home NodeB, a Home eNodeB, a site controller, an access point (AP), or a wireless router. The EDs 1210a-1210c are configured to interface and communicate with the FW 6000699PCT03 37Internet 1250 and may access the core network 1230, the PSTN 1240, or the other networks 1260.

[0247] In the embodiment shown in FIG.12, the base station 1270a forms part of the RAN 1220a, which may include other base stations, elements, or devices. Also, the base station 1270b forms part of the RAN 1220b, which may include other base stations, elements, or devices. Each base station 1270a-1270b operates to transmit or receive wireless signals within a particular geographic region or area, sometimes referred to as a “cell.” In some embodiments, multiple-input multiple-output (MIMO) technology may be employed having multiple transceivers for each cell.

[0248] The base stations 1270a-1270b communicate with one or more of the EDs 1210a-1210c over one or more air interfaces 1290 using wireless communication links. The air interfaces 1290 may utilize any suitable radio access technology.

[0249] It is contemplated that the system 1200 may use multiple channel access functionality, including such schemes as described above. In particular embodiments, the base stations and EDs implement 5G New Radio (NR), LTE, LTE-A, or LTE-B. Of course, other multiple access schemes and wireless protocols may be utilized.

[0250] The RANs 1220a-1220b are in communication with the core network 1230 to provide the EDs 1210a-1210c with voice, data, application, Voice over Internet Protocol (VoIP), or other services. Understandably, the RANs 1220a-1220b or the core network 1230 may be in direct or indirect communication with one or more other RANs (not shown). The core network 1230 may also serve as a gateway access for other networks (such as the PSTN 1240, the Internet 1250, and the other networks 1260). In addition, some or all of the EDs 1210a-1210c may include functionality for communicating with different wireless networks over different wireless links using different wireless technologies or protocols. Instead of wireless communication (or in addition thereto), the EDs may communicate via wired communication channels to a service provider or switch (not shown), and to the Internet 1250.

[0251] Although FIG.12 illustrates one example of a communication system, various changes may be made to FIG.12. For example, the communication system 1200 could include any number of EDs, base stations, networks, or other components in any suitable configuration.

[0252] FIGs.13A and 13B illustrate example devices that may implement the methods and teachings according to this disclosure. In particular, FIG.13A illustrates an example ED 1310, and FIG.13B illustrates an example base station 1110. These components could be used in the system 1200 or in any other suitable system.

[0253] As shown in FIG.13A, the ED 1310 includes at least one processing unit 1300. The processing unit 1300 implements various processing operations of the ED 1310. For FW 6000699PCT03 38example, the processing unit 1300 could perform signal coding, data processing, power control, input / output processing, or any other functionality enabling the ED 1310 to operate in the system 1200. The processing unit 1300 also supports the methods and teachings described in more detail above. Each processing unit 1300 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 1300 could, for example, include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

[0254] The ED 1310 also includes at least one transceiver 1302. The transceiver 1302 is configured to modulate data or other content for transmission by at least one antenna or NIC (Network Interface Controller) 1304. The transceiver 1302 is also configured to demodulate data or other content received by the at least one antenna 1304. Each transceiver 1302 includes any suitable structure for generating signals for wireless or wired transmission or processing signals received wirelessly or by wire. Each antenna 1304 includes any suitable structure for transmitting or receiving wireless or wired signals. One or multiple transceivers 1302 could be used in the ED 1310, and one or multiple antennas 1304 could be used in the ED 1310. Although shown as a single functional unit, a transceiver 1302 could also be implemented using at least one transmitter and at least one separate receiver.

[0255] The ED 1310 further includes one or more input / output devices 1306 or interfaces (such as a wired interface to the Internet 1250). The input / output devices 1306 facilitate interaction with a user or other devices (network communications) in the network. Each input / output device 1306 includes any suitable structure for providing information to or receiving information from a user, such as a speaker, microphone, keypad, keyboard, display, or touch screen, including network interface communications.

[0256] In addition, the ED 1310 includes at least one memory 1308. The memory 1308 stores instructions and data used, generated, or collected by the ED 1310. For example, the memory 1308 could store software or firmware instructions executed by the processing unit(s) 1300 and data used to reduce or eliminate interference in incoming signals. Each memory 1308 includes any suitable volatile or non-volatile storage and retrieval device(s). Any suitable type of memory may be used, such as random access memory (RAM), read only memory (ROM), hard disk, optical disc, subscriber identity module (SIM) card, memory stick, secure digital (SD) memory card, and the like.

[0257] As shown in FIG.13B, the base station 1110 includes at least one processing unit 1350, at least one transceiver 1352, which includes functionality for a transmitter and a receiver, one or more antennas 1356, at least one memory 1358, and one or more input / output devices or interfaces 1366. A scheduler, which would be understood by one FW 6000699PCT03 39skilled in the art, is coupled to the processing unit 1350. The scheduler could be included within or operated separately from the base station 1110. The processing unit 1350 implements various processing operations of the base station 1110, such as signal coding, data processing, power control, input / output processing, or any other functionality. The processing unit 1350 can also support the methods and teachings described in more detail above. Each processing unit 1350 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 1350 could, for example, include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

[0258] Each transceiver 1352 includes any suitable structure for generating signals for wireless or wired transmission to one or more EDs or other devices. Each transceiver 1352 further includes any suitable structure for processing signals received wirelessly or by wire from one or more EDs or other devices. Although shown combined as a transceiver 1352, a transmitter and a receiver could be separate components. Each antenna 1356 includes any suitable structure for transmitting or receiving wireless or wired signals. While a common antenna 1356 is shown here as being coupled to the transceiver 1352, one or more antennas 1356 could be coupled to the transceiver(s) 1352, allowing separate antennas 1356 to be coupled to the transmitter and the receiver if equipped as separate components. Each memory 1358 includes any suitable volatile or non-volatile storage and retrieval device(s). Each input / output device 1366 facilitates interaction with a user or other devices (network communications) in the network. Each input / output device 1366 includes any suitable structure for providing information to or receiving / providing information from a user, including network interface communications.

[0259] FIG.14 is a block diagram of a computing system 1400 that may be used for implementing the devices and methods disclosed herein. For example, the computing system can be any entity of UE, access network (AN), mobility management (MM), session management (SM), user plane gateway (UPGW), or access stratum (AS). Specific devices may utilize all of the components shown or only a subset of the components, and levels of integration may vary from device to device. Furthermore, a device may contain multiple instances of a component, such as multiple processing units, processors, memories, transmitters, receivers, etc. The computing system 1400 includes a processing unit 1402. The processing unit includes a central processing unit (CPU) 1414, memory 1408, and may further include a mass storage device 1404, a video adapter 1410, and an I / O interface 1412 connected to a bus 1420.

[0260] The bus 1420 may be one or more of any type of several bus architectures including a memory bus or memory controller, a peripheral bus, or a video bus. The CPU FW 6000699PCT03 401414 may comprise any type of electronic data processor. The memory 1408 may comprise any type of non-transitory system memory such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), or a combination thereof. In an embodiment, the memory 1408 may include ROM for use at boot-up, and DRAM for program and data storage for use while executing programs.

[0261] The mass storage 1404 may comprise any type of non-transitory storage device configured to store data, programs, and other information and to make the data, programs, and other information accessible via the bus 1420. The mass storage 1404 may comprise, for example, one or more of a solid state drive, hard disk drive, a magnetic disk drive, or an optical disk drive.

[0262] The video adapter 1410 and the I / O interface 1412 provide interfaces to couple external input and output devices to the processing unit 1402. As illustrated, examples of input and output devices include a display 1418 coupled to the video adapter 1410 and a mouse, keyboard, or printer 1416 coupled to the I / O interface 1412. Other devices may be coupled to the processing unit 1402, and additional or fewer interface cards may be utilized. For example, a serial interface such as Universal Serial Bus (USB) (not shown) may be used to provide an interface for an external device.

[0263] The processing unit 1402 also includes one or more network interfaces 1406, which may comprise wired links, such as an Ethernet cable, or wireless links to access nodes or different networks. The network interfaces 1406 allow the processing unit 1402 to communicate with remote units via the networks. For example, the network interfaces 1406 may provide wireless communication via one or more transmitters / transmit antennas and one or more receivers / receive antennas. In an embodiment, the processing unit 1402 is coupled to a local-area network 1422 or a wide-area network for data processing and communications with remote devices, such as other processing units, the Internet, or remote storage facilities.

[0264] It should be appreciated that not all components in the devices described in FIGs.11-14 are required. In a non-limiting example, the ED 1310 may be implemented as an AIoT device 1310. But, the AIoT device 1310 may not include an input / output devices 1306 for providing information to or receiving information from a user, such as a speaker, microphone, keypad, keyboard, display, or touch screen. The transceiver 1302 of the AIoT device 1310 may be capable of transmitting by backscattering a radio wave received, instead of by generating the radio wave, for wireless communication purpose. In another non-limiting example, the system 1400 may be implemented as an AIoT device 1400 that does not include or use the mass storage device 1404, the video adapter 1410, the mouse, keyboard, or printer 1416, or the display 1418. FW 6000699PCT03 41

[0265] It should be appreciated that one or more steps of the embodiment methods provided herein may be performed by corresponding units or modules. For example, a signal may be transmitted by a transmitting unit or a transmitting module. A signal may be received by a receiving unit or a receiving module. A signal may be processed by a processing unit or a processing module. Other steps may be performed by a performing unit or module, a generating unit or module, an obtaining unit or module, a setting unit or module, an adjusting unit or module, an increasing unit or module, a decreasing unit or module, a determining unit or module, a modifying unit or module, a reducing unit or module, a removing unit or module, or a selecting unit or module. The respective units or modules may be hardware, software, or a combination thereof. For instance, one or more of the units or modules may be an integrated circuit, such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0266] Although the description has been described in detail, it should be understood that various changes, substitutions and alterations can be made without departing from the spirit and scope of this disclosure as defined by the appended claims. Moreover, the scope of the disclosure is not intended to be limited to the particular embodiments described herein, as one of ordinary skill in the art will readily appreciate from this disclosure that processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, may perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. FW 6000699PCT03 42

Claims

CLAIMS What is claimed is:

1. A method for wireless communication by a wireless device, comprising: assembling respective information bits for each orthogonal frequency division multiplexed (OFDM) symbol based on information bits in a message for a plurality of OFDM symbols to generate assembled information bits for each OFDM symbol; generating a time domain waveform for each OFDM symbol based on the assembled information bits for each OFDM symbol; cyclic shifting the time domain waveform for each OFDM symbol; after the cyclic shifting, transforming the time domain waveform for each OFDM symbol to generate complex modulation values for each OFDM symbol; generating subcarrier modulation values based on the complex modulation values; and applying a phase rotation to the subcarrier modulation values.

2. The method of claim 1, the assembling the respective information bits comprising: determining a repeating or redundant bit index for an OFDM symbol based on a cyclic shift value of a previous OFDM symbol; and inserting a repeating or redundant bit at a bit position based on the repeating or redundant bit index in the OFDM symbol, wherein the repeating or redundant bit has a same value as an incomplete bit of the previous OFDM symbol.

3. The method of any of claims 1-2, the assembling the respective information bits comprising: determining a repeating or redundant bit index for an OFDM symbol based on a repeating or redundant bit index lookup table, a number of On-Off Keying (OOK) symbols per OFDM symbol, and a position of the OFDM symbol in the message; and inserting a repeating or redundant bit at a bit position based on the repeating or redundant bit index in the OFDM symbol, wherein the repeating or redundant bit has a same value as an incomplete bit at an end of a previous OFDM symbol.

4. The method of any of claims 1-3, the cyclic shifting comprising: determining a cyclic shift value for an OFDM symbol in the message based on cyclic prefix (CP) lengths of previous OFDM symbols in the message, a CP length of the OFDM symbol, and a length of each OOK symbol in number of discrete Fourier transform (DFT) samples; and FW 6000699PCT03 43performing a left cyclic shift of the time domain waveform by the cyclic shift value.

5. The method of claim 4, wherein the cyclic shift value for the OFDM symbol in the message is based on: ^^^^^^^^^^^ = ^^^ ^^ ^^^^^^ , 2^^^^^^^^wherein ^^^^^^^^^^ is the cyclic shift value, k is an index to a k-th OFDM symbol in the message, ^^^^^^is the CP length of an i-th OFDM symbol in the message in number of DFT samples, and ^^^^is the length of each OOK symbol in number of DFT samples.

6. The method of any of claims 1-2, the cyclic shifting comprising: determining a cyclic shift value for an OFDM symbol based on a cyclic shift value lookup table, a number of On-Off Keying (OOK) symbols per OFDM symbol, and a position of the OFDM symbol in the message.

7. The method of any of claims 1-6, the applying the phase rotation comprising: determining a phase rotation value for an OFDM symbol in the message based on a previous phase rotation value of a previous OFDM symbol, a CP length of the OFDM symbol, a starting frequency index, a number of subcarriers, and a Fast Fourier Transform (iFFT) size; and applying the phase rotation value to the subcarrier modulation values.

8. The method of claim 7, wherein the phase rotation value is based on "#∙%&'() *+,)-*^.∙ / (0^^^^^1^ = 0, ^^^^ = ^^^ − 1^ +wherein ^^^^is the phase th OFDM symbol inthe message, ^4^ is the number of subcarriers allocated for transmitting the message,^^^^^^ is the CP length of the k-th OFDM symbol, ^^++5 is the iFFT size, and67"8∈{0,1,2,…, NiFFT -NSC}.

9. A method for wireless communication by a wireless device, comprising: generating a first signal by mapping a first encoded bit to a first time domain symbol and a second encoded bit to a second time domain symbol, wherein the first signal includes the first time domain symbol and the second FW 6000699PCT03 44time domain symbol, wherein the first encoded bit is 1, and the second encoded bit is 0, and wherein a first beginning portion of the first time domain symbol, a first ending portion of the first time domain symbol, a second beginning portion of the second time domain symbol, and a second ending portion of the second time domain symbol are the same; generating an orthogonal frequency division multiplexed (OFDM) symbol including a cyclic prefix (CP) based on the first signal; and transmitting the OFDM symbol.

10. The method of claim 9, further comprising: encoding a first information bit and a second information bit into a plurality of encoded bits including the first encoded bit and the second encoded bit, wherein the first information bit is 1, and the second information bit is 0, or wherein the first information bit is 0, and the second information bit is 1.

11. The method of any of claims 9-10, wherein the first information bit is encoded into a first codeword comprising two encoded bits [1, 0], and the second information bit is encoded into a second codeword comprising one encoded bit [0].

12. The method of claim 11, wherein the first codeword and the second codeword each further comprise one or more additional encoded bits of 1 at a first beginning of the first codeword and a second beginning of the second codeword.

13. The method of any of claims 9-12, wherein the first information bit and the second information bit are encoded into a first codeword and a second codeword based on Manchester encoding.

14. The method of any of claims 9-13, wherein symbol durations of the first time domain symbol and the second time domain symbol are the same, and the first time domain symbol is a constant high value over a first symbol duration of the first time domain symbol, wherein the second time domain symbol includes a first transition from the constant high value to a constant low value after a first duration corresponding to the second beginning portion of the second time domain symbol, and wherein the second time domain symbol further includes a second transition from the constant low value to the constant high value starting at a second duration corresponding to the second end portion of the second time domain symbol. FW 6000699PCT03 4515. The method of any of claims 10, wherein the first information bit is encoded into a first codeword comprising two encoded bits [0, 1], and the second information bit is encoded into a second codeword comprising one encoded bit [1], respectively.

16. The method of claim 15, wherein the first codeword and the second codeword each further comprise one or more additional encoded bits of 0 at a first beginning of the first codeword and a second beginning of the second codeword.

17. The method of claim 15, wherein the second time domain symbol is a constant high value over a second symbol duration of the second time domain symbol, and wherein the first time domain symbol includes a first transition from the constant high value to a constant low value after a first duration corresponding to the first beginning portion of the first time domain symbol, and wherein the first time domain symbol further includes a second transition from the constant low value to the constant high value starting at a second duration corresponding to the second end portion of the first time domain symbol.

18. The method of claim 14 or 17, wherein the first duration and the second duration are selected to correspond to at least a duration of the CP in the OFDM symbol.

19. The method of any of claims 9-18, the generating the OFDM symbol comprising: generating one or more second signals from the first signal, wherein each of the one or more second signals has a duration corresponding to an OFDM symbol duration of the OFDM symbol including the cyclic prefix; and generating one or more third signals from the one or more second signals by removing a number of samples corresponding to a CP duration from a corresponding beginning of each of the one or more second signals; generating a frequency domain representation of the one or more third signals; and applying the frequency domain representation to one or more subcarriers of an OFDM generator function.

20. The method of any of claims 9-19, the transmitting the OFDM symbol comprising: transmitting the OFDM symbol including the CP over a physical reader to device channel (PRDCH).

21. A method for wireless communication by a wireless device, comprising: receiving a first message using a first data rate, wherein the first message FW 6000699PCT03 46indicates a request for device capability; and transmitting a high data rate handling capability indication.

22. The method of claim 21, further comprising: receiving a second message using a second data rate, the second message comprising a first set of bits; and determining a second set of bits by discarding one or more bits in the first set of bits.

23. The method of claim 22, wherein the first data rate is a low data rate that does not require additional handling capability, and the second data rate is a high data rate that requires the additional handling capability at the wireless device.

24. The method of any of claims 21-23, wherein the first set of bits is a set of Manchester encoded bits or chips.

25. The method of claim 24, further comprising: determining a third set of bits by skipping one or more chips every M chips in the first set of bits, wherein M is a number of On-Off keying (OOK) chips per OFDM symbol; decoding a fourth set of bits from the third set of bits based on Manchester encoding; and determining the second set of bits by discarding one or more bits in the fourth set of bits.

26. The method of claim 22 or claim 25, wherein a number of the one or more chips or bits to be skipped or discarded is received in one of a configuration message or a preamble preceding the second message.

27. The method of claim 22 or claim 25, wherein a number of the one or more chips or bits to be skipped or discarded is determined based on any of M, a data rate indication, a subcarrier spacing, or an OFDM symbol duration.

28. The method of any of claims 21-27, wherein any of the first set of bits or the second set of bits include encoded chips or information bits.

29. An apparatus for wireless communication, comprising: at least one processor; and at least one non-transitory computer readable storage medium storing programming, the programming including instructions that, when executed by the at FW 6000699PCT03 47least one processor, cause the apparatus to perform a method according to any of claims 1-8.

30. An apparatus for wireless communication, comprising: at least one processor; and at least one non-transitory computer readable storage medium storing programming, the programming including instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to any of claims 9-20.

31. An apparatus for wireless communication, comprising: at least one processor; and at least one non-transitory computer readable storage medium storing programming, the programming including instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to any of claims 21-28.

32. A non-transitory computer-readable medium having instructions stored thereon that, when executed by a wireless device, cause the wireless device to perform a method according to any of claims 1-8.

33. A non-transitory computer-readable medium having instructions stored thereon that, when executed by a wireless device, cause the wireless device to perform a method according to any of claims 9-20.

34. A non-transitory computer-readable medium having instructions stored thereon that, when executed by a wireless device, cause the wireless device to perform a method according to any of claims 21-28. FW 6000699PCT03 48

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