Various communication systems may benefit from improved radio signaling. For example, communication systems may benefit from selective or partial filtering of a radio signal. A method, in certain embodiments, may include analyze at a network entity a radio signal comprising a plurality of orthogonal frequency division multiplexing symbols. The radio signal comprises at least one point of discontinuity between the plurality of symbols. The method may also include filtering a select time domain sample of the radio signal in the plurality of symbols. The select sample surrounds the at least one point of discontinuity. In addition, the method may include replacing the select time domain sample surrounding the at least one point of discontinuity of the radio signal with the filtered sample in the plurality of symbols.

An environmental sound generating apparatus generates an environmental sound signal representing an environmental sound that forms sound environment by being emitted. The environmental sound has at least one chain of phonemes constituted of individual phonemes which sound-emission start timings as one of attributes thereof are sequentially shifted. A plurality of subgroups are prepared each formed by combining individual plural pitches from pitches constituting a primary pitch group that is a group of phonemes musically treated as consonances if sounded simultaneously. One of the plurality of subgroups selected at random is set to each of the sections of the chain of phonemes, and each of the individual phonemes of each section of the chain of phonemes is set to a pitch selected at random from the plural pitches constituting the selected subgroup to attain hypersonic effects.

A method is provided for calibrating a device under calibration (DUC) for optimizing performance of the DUC. The method includes receiving stimulus signal characteristics of a stimulus signal to be generated by the signal generator, including modulation type and duty cycle, where the stimulus signal characteristics are within a normal operating range of the DUC; receiving average output power set points and RF carrier frequencies of a DUC output signal; outputting the stimulus signal characteristics to a signal generator for generating the stimulus signal; iteratively performing an optimization process, using DUC calibration parameters that are simultaneously adjusted between consecutive iterations of the optimization process, to determine corresponding error functions based on measured power supply currents, output powers and linearities of the DUC output signal for the consecutive iterations, respectively, until a difference between consecutive error function values reaches a specified minimum; and using values of the calibration parameters corresponding to a last iteration.

A direct current (DC)-DC converter that includes a first switching converter and a multi-stage filter is disclosed. The multi-stage filter includes at least a first inductance (L) capacitance (C) filter and a second LC filter coupled in series between the first switching converter and a DC-DC converter output. The first LC filter has a first LC time constant and the second LC filter has a second LC time constant, which is less than the first LC time constant. The first LC filter includes a first capacitive element having a first self-resonant frequency, which is about equal to a first notch frequency of the multi-stage filter.

Distance-based authentication is provided for mitigating undesirable interaction and/or attacks upon ranging systems, such as those involving vehicle entry or secure payment. As may be implemented in accordance with one or more embodiments, a leading edge of one or more pulses in a waveform of a signal is obscured as part of distance-based authentication. For instance, noise may be generated via a noise modulation circuit and combined with some or all of a leading edge of a pulse. Distance-based authentication is provided by transmitting a signal with a waveform having the obscured portion of the leading edge, which operates to mitigate detection of the polarity of the leading edge or otherwise of the leading edge itself.

Distance-based authentication is provided for mitigating undesirable interaction and/or attacks upon ranging systems, such as those involving vehicle entry or secure payment. As may be implemented in accordance with one or more embodiments, a leading edge of one or more pulses in a waveform of a signal is obscured as part of distance-based authentication. For instance, noise may be generated via a noise modulation circuit and combined with some or all of a leading edge of a pulse. Distance-based authentication is provided by transmitting a signal with a waveform having the obscured portion of the leading edge, which operates to mitigate detection of the polarity of the leading edge or otherwise of the leading edge itself.

Embodiments of the present invention provide a method and system of encryption, decryption, and encryption and decryption based on visible light communication. A transmit end performs a logical operation on an original data signal and a pseudocode signal varying with a unit interval to obtain a scrambling code signal, and sends the scrambling code signal in a form of a visible light signal. A receive end receives the visible light signal sent by the transmit end, and converts the visible light signal into a digital signal; and decodes the digital signal and a pseudocode signal varying with a unit interval, so as to obtain the original data signal. The visible light signal transmitted between the transmit end and the receive end is not original data, but a scrambling code signal varying with a unit interval, thereby improving security of the photonic Internet of Things.

Embodiments of the present invention provide a method and system of encryption, decryption, and encryption and decryption based on visible light communication. A transmit end performs a logical operation on an original data signal and a pseudocode signal varying with a unit interval to obtain a scrambling code signal, and sends the scrambling code signal in a form of a visible light signal. A receive end receives the visible light signal sent by the transmit end, and converts the visible light signal into a digital signal; and decodes the digital signal and a pseudocode signal varying with a unit interval, so as to obtain the original data signal. The visible light signal transmitted between the transmit end and the receive end is not original data, but a scrambling code signal varying with a unit interval, thereby improving security of the photonic Internet of Things.

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.

In order to prevent, without significantly reducing the power of a transmission path, a signal unnecessary for a branch station from being intercepted at the branch station, a node apparatus comprises: a first optical unit that outputs a first optical signal received from a first terminal station and addressed to a second terminal station and also outputs a second optical signal received from the first terminal station and addressed to a third terminal station; and a second optical unit that receives the first and second optical signals outputted from the first optical unit, optically removes a portion of the spectrum of the first optical signal, thereby generating a fourth optical signal, and passes the second optical signal as it is, thereby transmitting the second optical signal together with the fourth optical signal to the third terminal station.