A transmitter comprising a phase computation circuit configured to receive a complex baseband signal comprising an in-phase signal and a quadrature signal forming an I-Q data pair, and determine a first rotation angle and a second rotation angle based on the I-Q data pair. The transmitter further comprises a modulation circuit coupled to the phase computation circuit configured to determine a three-level modulated waveform having a lower negative level, a zero level and a higher positive level, based on the first rotation angle and the second rotation angle; and generate the three-level modulated waveform based on the determination.

A communications system may include radio frequency (RF) circuitry, an antenna assembly, and an RF cable coupling the RF circuitry and the antenna assembly. The antenna assembly may include an antenna and RF impedance selection circuitry coupled thereto. The RF circuitry may be configured to communicate RF signals with the antenna via the RF cable, and communicate RF impedance selection signals to the RF impedance selection circuitry via the RF cable and using an alternating pulse width modulation scheme.

Methods, systems, and devices for techniques for communicating multi-level signals are described. A first device may be configured to communicate signals with a second device according to a modulation scheme. The first device may transmit a first signal to the second device at a first voltage level of the modulation scheme corresponding to a first multi-bit value. The first device may select a second voltage level of the modulation scheme based on a difference between the first voltage level and a third voltage level of the PAM scheme, and may transmit a second signal to the second device at the second voltage level to indicate a second multi-bit value corresponding to the third voltage level. The second device may decode the second signal to determine the second multi-bit value based on receiving the first signal at the first voltage level and the second signal at the second voltage level.

A device includes a first interface to receive a signal from a first communication link, wherein the receive signal includes out-of-band (OOB) information. A detector coupled to the first interface detects the OOB information. An encoder coupled to the detector encodes the OOB information into one or more symbols (e.g., control characters). A second interface is coupled to the encoder and a second communication link (e.g., a serial transport path). The second interface transmits the symbols on the second communication link. The device also includes mechanisms for preventing false presence detection of terminating devices.

Embodiments of the present invention disclose systems and methods for providing an ATC Overlay data link. Through embodiments of the present invention, existing ATC (or other) modulated signals using existing standard frequencies may be utilized to transmit (e.g., from an aircraft transponder) additional information in a manner that does not render the transmitted signal unrecognizable by legacy ATC equipment. Legacy equipment will be able to demodulate and decode information that was encoded in the transmitted signal in accordance with preexisting standard modulation formats, and updated equipment can also extract the additional information that was overlaid on transmitted signals.

Using a transformation based at least in part on a non-simple orthogonal or unitary matrix, data may be transmitted over a data bus in a manner that is resilient to one or more types of signal noise, that does not require a common reference at the transmission and acquisition points, and/or that has a pin-efficiency that is greater than 50% and may approach that of single-ended signaling. Such transformations may be implemented in hardware in an efficient manner. Hybrid transformers that apply such transformations to selected subsets of signals to be transmitted may be used to adapt to various signal set sizes and/or transmission environment properties including noise and physical space requirements of given transmission environments.

A handshaking process for time-reversal wireless communication is provided. A first device receives a handshake signal transmitted from a second device through multiple propagation paths, the handshake signal including a preamble and a training sequence, in which the training sequence includes a sequence of symbols known to the first and second devices. A synchronization index is determined based on the preamble, and the training sequence in the handshake signal is identified based on the synchronization index. A channel response signal is determined based on the received training sequence, and a signature waveform that is a time-reversed signal of the channel response signal is generated. A transmission signal is generated based on transmit data and the signature waveform, in which the transmit data are data configured to be transmitted to the second device.

An apparatus for a mobile communication device adapted for digital pre-distortion that includes a memory and a processor operatively coupled to the memory of the processor. The processor receives a first input signal and also receives a first output signal from a power amplifier that is based on the first input signal. The processor additionally varies compression applied to a second input signal based on the first output signal of the power amplifier, generates a distortion compensation vector for the second input signal based on the first output signal of the power amplifier, and also varies an input excitation signal supplied to the power amplifier based on the first output signal of the power amplifier.

An apparatus for a mobile communication device adapted for digital pre-distortion that includes a memory and a processor operatively coupled to the memory of the processor. The processor receives a first input signal and also receives a first output signal from a power amplifier that is based on the first input signal. The processor additionally varies compression applied to a second input signal based on the first output signal of the power amplifier, generates a distortion compensation vector for the second input signal based on the first output signal of the power amplifier, and also varies an input excitation signal supplied to the power amplifier based on the first output signal of the power amplifier.

A device configured to perform wireless communication includes: a pre-distortion circuit configured to generate a pre-distorted input signal by performing pre-distortion on an input signal based on a parameter set comprising a plurality of coefficients; a power amplifier configured to generate an output signal by amplifying an RF signal based on the pre-distorted input signal; and a parameter obtaining circuit configured to obtain second memory polynomial modeling information corresponding to an operating frequency band based on first memory polynomial modeling information corresponding to each of a plurality of frequency sections and obtain a parameter set according to an indirect learning structure by using the second memory polynomial modeling information.