Methods, systems, and devices for wireless communication are described. A user equipment (UE) may receive control signaling indicating a preamble configuration. The UE may receive a preamble in a time domain. The preamble may include a set of modulated bits during a first portion of an initial symbol duration of a slot. The set of modulated bits may include one or more of a first subset of network temporary identifier bits or a second subset of modulation and coding scheme (MCS) bits. The UE may process the preamble during a second portion of the initial symbol duration of the slot based on the preamble configuration.

A communication device selects a frequency bandwidth via which a physical layer (PHY) protocol data unit (PPDU) will be transmitted in a vehicular communication network, and generates, the PPDU i) according to a downclocking ratio of 1/2, and ii) based on an orthogonal frequency division multiplexing (OFDM) numerology defined by an IEEE 802.11ac Standard. In response to the selected frequency bandwidth being 10 MHz, the PPDU is generated according to the downclocking ratio of 1/2 and based on the OFDM numerology defined by the IEEE 802.11ac Standard for 20 MHz PPDUs. In response to the selected frequency bandwidth being 20 MHz, the PPDU is generated according to the downclocking ratio of 1/2 and based on the OFDM numerology defined by the IEEE 802.11ac Standard for 40 MHz PPDUs.

A method for implementing a fast UBDM transform includes receiving a first, input vector via a processor, and partitioning the first vector to produce a magnitude vector and a sign vector. A second vector, including a modified magnitude vector and a modified sign vector, is generated by: applying a permutation to the magnitude vector to produce the modified magnitude vector, converting the sign vector, based on an algorithm, into an intermediate sign vector, and applying nonlinear layers to the intermediate sign vector. Each nonlinear layer includes a permutation, an S-box transformation, a diffusive linear operation and/or an Xor operation. Multiple linear layers are applied to the second vector to produce a third vector, the third vector being a transformed version of the first vector. A first signal representing the third vector is sent to at least one transmitter for transmission of a second signal representing the transformed data vector.

Provided are a data transmission method and a network device, the method including: configuring a multiple access mode of uplink transmission for a terminal device; sending the multiple access mode of uplink transmission to the terminal device. The multiple access mode of uplink transmission is used for the terminal device to determine a multiplexing mode of a first uplink signal and a second uplink signal on a target time domain resource, wherein the first uplink signal and the second uplink signal are signals which the terminal device is scheduled to transmit on the target time domain resource simultaneously.

Utilizing a fast Fourier transform (FFT) to cancel a non-liner phase response of a digital infinite impulse response (IIR) lowpass filter is presented herein. An apparatus generates, via the digital IIR lowpass filter, respective discrete time domain orthogonal frequency-division multiplexing (OFDM) based digital output values comprising non-linear phase distortion; in response to removing respective cyclic prefix values from the respective discrete time domain OFDM based digital output values to obtain a group of discrete time domain OFDM based digital output values, generates, based on such values via a digital FFT, respective frequency domain OFDM based digital output values comprising a non-linear phase response of the digital FFT; and based on the non-linear phase response of the digital IIR lowpass filter, applies phase compensation to the respective frequency domain OFDM based digital output values to obtain frequency compensated frequency domain OFDM based digital output values comprising a linear phase response.

A multiple access method, a multiple access transmitter, and a multiple access receiver includes performing, by a transmitter, channel coding on a bit sequence to determine a coded sequence. The method also includes interleaving and/or scrambling the coded sequence, and performing multidimensional constellation modulation on the interleaved and/or scrambled sequence; performing grid mapping on the modulated symbol sequence to determine a mapped sequence, and transmitting the mapped sequence. The method also includes receiving, by a receiver, mixed signals from multiple transmitters, the mixed signals are obtained by performing, by each of the multiple transmitters, interleaving and/or scrambling, multidimensional constellation modulation and grid mapping on data. The method further includes decoding, by the receiver, mixed information according to interleaver information and/or scrambler information, multidimensional constellation information and grid mapping pattern information corresponding to each transmitter to obtain data corresponding to each transmitter.

Certain aspects of the present disclosure provide techniques for waveform parameters adaptation. Aspects provide for adapting waveforms to account for impairments that can occur when communicating in a high frequency band. A method that may be performed by a base station (BS) includes detecting one or more impairment conditions. The method includes determining a plurality of waveform parameters to adapt in response to the detected one or more impairment conditions. The method includes signaling the plurality of adapted waveform parameters to a user equipment (UE).

The disclosure deals with system and method for an over-the-air computation (AirComp) scheme for federated edge learning (FEEL) without channel state information (CSI) at the edge devices (EDs) or edge server (ES). The disclosure adopts the majority vote (MV) principle and defines multiple subcarriers and orthogonal frequency division multiplexing (OFDM) symbols for voting options, which reduces to frequency-shift keying (FSK) over OFDM subcarriers as a special case. Thus, FSK-based over-the-air computation is provided for federated edge learning without channel state information. Since the votes from EDs are separated on orthogonal resources, the proposed scheme eliminates the need for truncated-channel inversion (TCI) at the EDs and allows the ES to detect MV with a non-coherent detector. We also mitigate the peak-to-mean envelope power ratio (PMEPR) of the synthesized signals by using randomization symbols. Simulations show the proposed scheme provides high test accuracy in fading channels for both independent and identically distributed (IID) and non-IID data while resulting in OFDM symbols with lower PMEPRs as compared to one-bit broadband digital aggregation (OBDA) with quadrature amplitude modulation (QAM).

Methods, apparatus, and systems for reducing Peak Average Power Ratio (PAPR) in signal transmissions are described. In one example aspect, a wireless communication method includes determining, for an input sequence, an output sequence. The output sequence corresponds to an output of a convolutional modulation between a set of coefficients and an intermediate sequence. The intermediate sequence is generated by inserting N zero coefficients between coefficients of the input sequence. The number of non-zero coefficients in the set of coefficients is based on N, N being a positive integer. Values of the non-zero coefficients correspond to values between 0 to π/2 to reduce a peak to average power ratio of the output sequence. The method also includes generating a waveform using the output sequence.

Methods, apparatus, and systems for reducing Peak Average Power Ratio (PAPR) in signal transmissions are described. In one example aspect, a wireless communication method includes determining, for an input sequence, an output sequence corresponding to an output of a convolutional modulation between a plurality of values and an intermediate sequence. The intermediate sequence is generated by inserting a set of coefficients between coefficients of the input sequence. Each non-zero coefficient of the set of coefficients is inserted between a first adjacent coefficient and a second adjacent coefficient. Each non-zero coefficient has a power that is between a first power of the first adjacent coefficient and a second power of the second adjacent coefficient and a phase value between a first phase value of the first adjacent coefficient and a second phase value of the second adjacent coefficient. The method also includes generating a waveform using the output sequence.