A transmitter includes: a modulation circuit that modulates a data sequence using QAM by mapping the data sequence to only four symbols each of which differs in phase by 90 degrees from an adjacent one of the four symbols and at least two of which have different amplitudes; and a transmission circuit that wirelessly transmits the data sequence mapped to the four symbols through the modulation by the modulation circuit, by assigning the data sequence mapped to the four symbols through the modulation by the modulation circuit to different subcarriers for Orthogonal Frequency Division Multiplexing (OFDM).

A network node operating in a communication network can determine a magnitude of a time sample of a modulated signal. The network node can determine a correction signal based on a difference between the magnitude of the time sample and a predetermined value. The network node can modify the modulated signal by the correction signal.

An electronic device may include wireless circuitry with a baseband processor, a transceiver, and an antenna. The transceiver may include a transmit path, a receive path, and a loopback path that couples the transmit path to the receive path. A passive all-pass filter may be interposed on the loopback path. Control circuitry may calibrate I/Q mismatch of the wireless circuitry using the all-pass filter to optimize the radio-frequency performance of the wireless circuitry. Performing I/Q mismatch calibration using the all-pass filter may serve to minimize area consumption in the transceiver, may minimize calibration time, and may allow for calibration over a relatively wide bandwidth.

The present disclosure relates to correction apparatus and correction methods. One example correction apparatus includes a first adjustment module, a plurality of second adjustment modules, a correction calculation module, and a plurality of non-ideal channels. One second adjustment module is disposed on one non-ideal channel. The first adjustment module is connected to each non-ideal channel. The correction calculation module is separately connected to the first adjustment module and the plurality of second adjustment modules. The correction calculation module is connected to an output end of each non-ideal channel. The non-ideal channel is a channel that outputs an output signal in response to a drive signal having an error value.

A communication unit comprises a modem configured to generate a first and second test digital quadrature signal. The modem is configured to: estimate a first sampling error performance associated with a first quadrature path from the first received test digital quadrature signal; estimate a second sampling error performance associated with a second quadrature path from the second received test digital quadrature signal; and generate at least one sampling error compensation signal based on the first estimated sampling error performance and second estimated sampling error performance to be applied to at least one of the receiver and transmitter.

Faulted messages in 5G or 6G are generally discarded and a retransmission is then requested. However, the faulted message contains valuable information despite the few faulted message elements. Retransmission is a time-consuming energy-intensive process. Therefore, the present disclosure pertains to procedures for determining which specific message elements, of a corrupted message, are actually faulted. To do so, the receiver can determine a modulation quality of each message element by measuring a difference between the amplitude levels of the message element and the predetermined amplitude levels of the modulation scheme. For example, the modulation scheme may involve an I-branch and an orthogonal Q-branch, each with a different amplitude. The message quality may be related to the deviation of each branch amplitude from the closest predetermined amplitude level of the modulation scheme. A large amplitude deviation indicates a suspicious message element. Many other aspects are also disclosed.

A scheme for generating asymmetric single sideband photonic vector signal at millimeter wave spectral region is described. At a transmitter, information bits to be transmitted are modulated using a vector modulation technique to generate a baseband signal. The baseband signal is converted into its single sideband (SSB) version using a complex frequency source having a first frequency. The real part of the upconverted signal is added to the real part of a second frequency source and is input as I component to an I/Q modulator. The imaginary part of the upconverted signal is added to the imaginary part of the second frequency source and is used as the Q component. The I/Q modulator is driven by a laser source at frequency fc. The resulting signal is transmitter over an optical transmission medium and upconverted by a single-ended photodiode to a desired radio-frequency (RF) carrier frequency.

Various arrangements for performing transmodulation of a forward feeder link are presented. A first data stream and a second data stream can be modulated into a higher-order modulation forward feeder link having a higher-order digital modulation scheme. A satellite can receive the higher-order modulation forward feeder link. The satellite can demodulate the higher-order modulator forward feeder link into a bit stream. This bit stream may then be remodulated and retransmitted as multiple forward user links.

A microelectromechanical system (MEMS) gyroscope sensor has a sensing mass and a quadrature error compensation control loop for applying a force to the sensing mass to cancel quadrature error. To detect fault, the quadrature error compensation control loop is opened and an additional force is applied to produce a physical displacement of the sensing mass. A quadrature error resulting from the physical displacement of the sensing mass in response to the applied additional force is sensed. The sensed quadrature error is compared to an expected value corresponding to the applied additional force and a fault alert is generated if the comparison is not satisfied.

Aspects relate to correcting Inphase/Quadrature (I/Q) imbalances across multiple wireless elements such as multiple receive elements or multiple transmit elements. In one example implementation, I/Q imbalances can be corrected using a digital circuit provided within a digital portion of a direct conversion wireless element (upconversion or downconversion) that implements only two multiplications and one addition per pair of I and Q samples.