Methods, systems, and devices for wireless communications are described. A user equipment (UE) may communicate with a base station by initiating a random access procedure with a two-root preamble. The UE may receive, from the base station, control signaling that indicates a set of root preamble sequences. The UE may transmit, to the base station, a preamble signal that is generated based on a first root preamble sequence and a second root preamble sequence of the set of root preamble sequences. The UE may then monitor for a preamble response based on the preamble signal. In some cases, the base station may be a base station in a terrestrial network. In other cases, the base station may be a satellite in a non-terrestrial network (NTN).

A platform for updating one or more properties of one or more digital twins including receiving a request for one or more digital twins; retrieving the one or more digital twins required to fulfill the request from a digital twin datastore; retrieving one or more dynamic models corresponding to one or more properties that are depicted in the one or more digital twins indicated by the request; selecting data sources from a set of available data sources based on the one or more inputs of the one or more dynamic models; obtaining data from selected data sources; determining one or more outputs using the retrieved data as one or more inputs to the one or more dynamic models; and updating the one or more properties of the one or more digital twins based on the one or more outputs of the one or more dynamic models.

A wireless station includes at least one oscillator to output a reference signal, and an error calculator to calculate a frequency of the reference signal and calculate a frequency error by subtracting a target frequency of the reference signal from the calculated frequency of the reference signal. The wireless station further includes a modulation data generator to generate modulation data by adding a correction value, varying in negative correlation with the frequency error calculated by the error calculator, to data to be transmitted, and a modulator to conduct frequency modulation on the basis of the modulation data and the reference signal.

Systems and techniques are described that are directed to filter frequency response shift compensation, including compensating for shifting in the rejection band of the filter. Compensation for the shifting in the rejection band can include applying a pre-distortion to attenuate edge resource units (RUs), and applying PHY Protocol Data Unit (PPDU) scheduling schemes. For example, a PPDU scheduling scheme reduce bandwidth in the channel, thereby dropping the out of band RUs. Front ends provide feedback to a respective radio, which allows that radio to apply the appropriate pre-distortion. The front ends can include one or more filters enabling frequency domain coexistence between collocated radios operating in the differing Wi-Fi bands, and a coupler that provides the feedback indicating the frequency response shift to a radio. The radio can then apply a digital pre-distortion to compensate for the shifting in the rejection band.

A method for carrier aggregation receives a signal with multiple non-contiguous carrier bands. Frequency converting of the signal to a compressed single intermediate frequency band with a pseudonoise code applied to a local oscillation of each of the multiple non-contiguous carrier bands while maintaining separation of the multiple non-contiguous carrier bands permits reduced complexity digital signal processing to detect spectral power density and demodulate waveforms across multiple channels A receiver includes a pseudorandom noise generator applying a pseudo noise code to the local oscillator generator to produce a unique set of spectral tones in the output signal that sample-specific channels over the multiple non-contiguous carrier bands.

A method of transmitting, by a transmitting device, an orthogonal frequency division multiplexing (OFDM) signal in a wireless communication system, the method including: generating, by a digital module of the transmitting device, a frequency-shifted OFDM baseband signal by performing frequency up-shift of a first signal by a difference between a carrier frequency f.sub.0 and a first frequency f.sub.base, wherein the first frequency f.sub.base is, among frequencies corresponding to integer multiples of 128Δf, closest to the carrier frequency f.sub.0, and wherein Δf is an OFDM subcarrier spacing; up-converting, by an analog oscillator of the transmitting device, the frequency-shifted OFDM baseband signal by the first frequency f.sub.base to generate an OFDM symbol signal at the carrier frequency f.sub.0; and transmitting the OFDM symbol signal at the carrier frequency f.sub.0.

When the ultra-low power mm-scale sensor node does not have a crystal oscillator and phase-lock loop, it inevitably exhibits significant carrier frequency offset (CFO) and sampling frequency offset (SFO) with respect to the reference frequencies in the gateway. This disclosure enables efficient real-time calculation of accurate SFO and CFO at the gateway, thus the ultra-low power mm-scale sensor node can be realized without a costly and bulky clock reference crystal and also power-hungry phase lock loop. In the proposed system, the crystal-less sensor starts transmission with repetitive RF pulses with a constant interval, followed by the data payload using pulse-position modulation (PPM). A proposed algorithm uses a two-dimensional (2D) fast Fourier transform (FFT) based process that identifies the SFO and CFO at the same time to establish successful wireless communication between the gateway and crystal-less sensor nodes.

An apparatus and method for carrier frequency estimation include a carrier frequency estimator having: a frequency input terminal disposed to receive a frequency-domain input signal comprising a plurality of symbols; a plurality of candidate pipelines, each comprising a frequency adder coupled to the frequency input terminal, a bit converter coupled to the frequency adder, a multi-bit buffer coupled to the bit converter; and a correlator coupled to the multi-bit buffer, respectively; and a candidate pipeline selector coupled to the correlators.

A wireless device includes a radio transceiver, and a digital transmitter configured to transmit, via the radio transceiver, a first data symbol, and to transmit, via the radio transceiver, a repetition of the first data symbol immediately after the first data symbol, where the first data symbol forms a cyclic prefix for the repetition of the first data symbol.

Methods, systems, and devices for wireless communications are described. A user equipment (UE) may transmit a random access preamble to a base station as part of a two-step random access procedure. The UE may generate the preamble by identifying a discrete Fourier transform (DFT) matrix and generating a set of sequences based on the DFT matrix. Each sequence of the set of sequences may be generated by selecting a column of the DFT matrix and performing deterministic sampling of respective entries from the selected column in accordance with a sampling function. The UE may then select a sequence from the set of sequences based on generating the set of sequence. The UE may transmit the selected sequence to a wireless device (e.g., a base station).