Methods, systems, and devices for wireless communication are described. A wireless device, such as a device in a wireless local area network, may use a radio frame structure that includes a high efficiency (HE) signal field and an HE data field for communications, for example, over shared radio frequency spectrum. One or more bits or symbols within the HE signal field may be adjusted to avoid a high peak-to-average power ratio (PAPR). In some cases, the adjustment may be to a signal A (SIG-A) or signal B (SIG-B) field. In some examples, a random bit sequence may be used for padding in a signal field. In other examples, bits may be reversed or scrambled. In yet other examples, bits may be modulated and a phase rotation may be applied to the corresponding signal.

Various embodiments include a power amplifier with crest factor reduction embodied by first circuitry for producing a correlated out-of-band noise signal for controlling the adjacent channel leakage ratio (ACLR) of a communication device; and second circuitry for providing an output signal for controlling the error vector magnitude (EVM) of a digital radio. The ACLR and the EVM are concurrently individually controllable. Additional apparatus is described.

A very high frequency (VHF) transceiver can include an amplitude and phase shift keying (APSK) modulator configured to modulate signals for transmission across a first VHF channel of a plurality of VHF channels used to communicate between or among aircraft and one or more ground stations. Each of the VHF channels can have a bandwidth of at least 8.33 kilo Hertz (kHz) with a data rate per Hertz (Hz) greater than or equal to 3 bits per second per Hz (bps/Hz). The VHF transceiver can include a power amplifier configured to amplify the modulated signals prior to the transmission. The VHF transceiver can include a linearity controller configured to control linearity of the power amplifier according to at least one of a Cartesian feedback amplifier linearization, pre-distortion amplifier linearization or feedforward amplifier linearization to mitigate nonlinear distortion associated with signals output by the power amplifier.

Various aspects described herein relate to resolving failures in digital pre-distortion (DPD) training in wireless communications. A failure during DPD training can be identified for a transceiver. One or both of a severity of the failure or a type of the failure can be determined. It can also be determined whether to perform self-recovery from the failure to continue the DPD training based at least in part on one or both of the severity of the failure or the type of the failure.

An FEC coder in a transmission device according to an exemplary embodiment of the present disclosure performs BCH coding and LDPC coding based on whether a code length of the LDPC coding is a 16k mode or a 64k mode. A mapper performs mapping in an I-Q coordinate to perform conversion into an FEC block, and outputs pieces of mapping data (cells). The mapper defines different non-uniform mapping patterns with respect to different code lengths even an identical coding rate is used by the FEC coder. This configuration improves a shaping gain for different error correction code lengths in a transmission technology in which modulation of the non-uniform mapping pattern is used.

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.

Methods, systems, and devices for wireless communications are described. A transmitting device may modulate a first binary sequence using binary phase shift keying on a first axis of a complex plane. The device may modulate a second binary sequence using binary phase shift keying on a second plane of a complex axis. The first axis and the second axis may be orthogonal. The device may transmit the first binary sequence and the second binary sequence according to the modulation of the first binary sequence and the second binary sequence.

There is provided spectrum shaping of a signal. A frequency-domain representation of the signal to be spectrum-shaped is provided. The signal is associated with a set of constellation points having a minimum distance. A spectrum-shaped signal is determined by altering a proper subset of the constellation points while maintaining the minimum distance between all of the constellation points. The spectrum-shaped signal is transformed into a time-domain signal.

A system and method including multi-dimensional coded modulation wherein symbols within successive blocks of symbols are mapped using at least two different constellations to differentiate the symbols from each other. At least one data bit is encoded by an order of the symbols within each block of symbols. The receiver decodes the data by decoding at least one bit from the order of the symbols mapped with the first and second constellations.

An FEC coder in a transmission device according to an exemplary embodiment of the present disclosure performs BCH coding and LDPC coding based on whether a code length of the LDPC coding is a 16k mode or a 64k mode. A mapper performs mapping in an I-Q coordinate to perform conversion into an FEC block, and outputs pieces of mapping data (cells). The mapper defines different non-uniform mapping patterns with respect to different code lengths even an identical coding rate is used by the FEC coder. This configuration improves a shaping gain for different error correction code lengths in a transmission technology in which modulation of the non-uniform mapping pattern is used.