A method performed in a base station for frequency calibration of a receiver is disclosed. The base station generates a first signal with periodic ASK modulation and transmits the first signal as a preamble or frequency marker signal to facilitate frequency calibration of the receiver. The receiver sweeps its oscillator frequency to detect if there is a preamble or frequency marker signal present. When it is determined that there is a signal present, the oscillator frequency of the receiver is calibrated to the transmitting frequency of the base station. The base station then transmits a second signal as a wakeup signal to the receiver.

A method performed in a base station for frequency calibration of a receiver is disclosed. The base station generates a first signal with periodic ASK modulation and transmits the first signal as a preamble or frequency marker signal to facilitate frequency calibration of the receiver. The receiver sweeps its oscillator frequency to detect if there is a preamble or frequency marker signal present. When it is determined that there is a signal present, the oscillator frequency of the receiver is calibrated to the transmitting frequency of the base station. The base station then transmits a second signal as a wakeup signal to the receiver.

Methods and systems are described for measuring a vertical opening of a signal eye of a pulse amplitude modulated (PAM) signal received over a channel to determine a vertically-centered voltage decision threshold of a sampler receiving a sampling clock, determining channel-characteristic parameters indicative of a frequency response of the channel, determining a correctional vernier value from the channel-characteristic parameters, and generating a horizontally-centered voltage decision threshold that introduces a horizontal sampling offset in the sampling clock in a direction closer to a horizontal center of the signal eye by combining the vertically-centered voltage decision threshold and the correctional vernier value.

Methods and systems are described for measuring a vertical opening of a signal eye of a pulse amplitude modulated (PAM) signal received over a channel to determine a vertically-centered voltage decision threshold of a sampler receiving a sampling clock, determining channel-characteristic parameters indicative of a frequency response of the channel, determining a correctional vernier value from the channel-characteristic parameters, and generating a horizontally-centered voltage decision threshold that introduces a horizontal sampling offset in the sampling clock in a direction closer to a horizontal center of the signal eye by combining the vertically-centered voltage decision threshold and the correctional vernier value.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive an indication of a non-linearity model associated with one or more downlink communications. The UE may receive the one or more downlink communications based at least in part on the non-linearity model. Numerous other aspects are described.

Logic may define one or more wake-up preambles suitable for high data rates for a wake-up radio (WUR) packet. Logic may define wake-up preamble with different counts of symbols. Logic may generate a wake-up preamble as an on-off keying (OOK) signal. Logic may generate and receive a wake-up preamble that signals a high data transmission rate with respect to data rates defined for WUR packet transmissions. Logic may generate or receive a preamble that signals a rate of transmission of the WUR packet as 250 kilobits per second. Logic may transmit or receive bits of the wake-up preamble as two microsecond orthogonal frequency-division multiplexing (OFDM) based pulses, wherein each two microsecond OFDM based pulse is based on a 32-point Fast Fourier Transform (FFT) in a 20 Megahertz (MHz) bandwidth, with a subcarrier spacing of 625 Kilohertz (KHz) to produce six subcarriers in a four MHz bandwidth.

Logic may define one or more wake-up preambles suitable for high data rates for a wake-up radio (WUR) packet. Logic may define wake-up preamble with different counts of symbols. Logic may generate a wake-up preamble as an on-off keying (OOK) signal. Logic may generate and receive a wake-up preamble that signals a high data transmission rate with respect to data rates defined for WUR packet transmissions. Logic may generate or receive a preamble that signals a rate of transmission of the WUR packet as 250 kilobits per second. Logic may transmit or receive bits of the wake-up preamble as two microsecond orthogonal frequency-division multiplexing (OFDM) based pulses, wherein each two microsecond OFDM based pulse is based on a 32-point Fast Fourier Transform (FFT) in a 20 Megahertz (MHz) bandwidth, with a subcarrier spacing of 625 Kilohertz (KHz) to produce six subcarriers in a four MHz bandwidth.

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.

A faulted 5G/6G message may be recovered by finding the faulted message elements and altering them until the fault is corrected. Disclosed are methods to evaluate the modulation quality of each message element using multiple criteria. The receiver can determine a first quality by measuring the overall (sum-signal) amplitude and phase of each message element, and comparing to the predetermined amplitude and phase levels. The receiver can determine a second quality by separating the overall wave into orthogonal components (branches) and comparing the branch amplitudes to the predetermined levels. The receiver can determine a third quality according to the SNR of the overall signal and the two branch signals. By combining the first, second, and third quality factors, the receiver can identify the most likely faulted message elements. The receiver can then alter the worst message elements in a nested grid search to find the correct message version.

A faulted 5G/6G message may be recovered by finding the faulted message elements and altering them until the fault is corrected. Disclosed are methods to evaluate the modulation quality of each message element using multiple criteria. The receiver can determine a first quality by measuring the overall (sum-signal) amplitude and phase of each message element, and comparing to the predetermined amplitude and phase levels. The receiver can determine a second quality by separating the overall wave into orthogonal components (branches) and comparing the branch amplitudes to the predetermined levels. The receiver can determine a third quality according to the SNR of the overall signal and the two branch signals. By combining the first, second, and third quality factors, the receiver can identify the most likely faulted message elements. The receiver can then alter the worst message elements in a nested grid search to find the correct message version.