Systems and apparatuses for wireless power transfer system are described. A receiver may send an amplitude shift key (ASK) signal to a transmitter. The transmitter may receive the ASK signal from the receiver. The transmitter may perform a demodulation on the ASK signal. The transmitter may, in response to a failure to demodulate the ASK signal, encode a notification of failure in a frequency shift key (FSK) signal. The transmitter may transmit the FSK signal to the receiver. The receiver may receive the FSK signal. The receiver may perform a function to resolve the failure to demodulate the ASK signal.

Various embodiments of this disclosure relate to generation and reception of signals comprising cyclically shifted basis functions. A device may obtain a set of modulation symbols and modulate a plurality of basis functions based on the set of modulation symbols to generate a signal. The plurality of basis functions may comprise cyclically shifted versions of a basis function and a periodic autocorrelation function of the basis function may comprise an ideal (e.g., perfect) periodic autocorrelation function.

The invention discloses a modulator, a demodulator and a wireless communication system. The wireless communication system comprises a modulator and a demodulator. The modulator is suitable for generating a target linear frequency modulation signal, wherein the target linear frequency modulation signal is a signal of which the frequency is varied linearly over time, wherein the phase of the target linear frequency modulation signal is determined by an initial frequency and a frequency stepping of the target linear frequency modulation signal, and the frequency stepping is determined by the bandwidth of the target linear frequency modulation signal and the spreading factor of the target linear frequency modulation signal. The demodulator is suitable for demodulating the target linear frequency modulation signal. According to the scheme, power consumption can be reduced while long-distance signal transmission is realized.

This application provides communication apparatuses and methods for signal transmission and reception, applied to, for example, backscatter communications. In an example method, a tag device receives a downlink excitation signal, where the downlink excitation signal is a linear frequency modulated signal or a multi-carrier linear frequency modulated signal. The tag device generates an uplink reflection signal according to the downlink excitation signal and uplink information. The tag device sends the uplink reflection signal to a network device. When receiving the uplink reflection signal from the tag device and receiving the downlink excitation signal, the network device performs fractional Fourier transform on the uplink reflection signal and the downlink excitation signal, to obtain an uplink frequency domain reflection signal and a downlink frequency domain excitation signal. The uplink frequency domain reflection signal and the downlink frequency domain excitation signal do not overlap each other.

In an embodiment, an electronic device may include a first frequency synthesizing circuit outputting a second electronic signal from a first electronic signal, a second frequency synthesizing circuit outputting a fourth electronic signal for converting a frequency of a third electronic signal obtained from the first electronic signal based on the second electronic signal, and a communication processor. The communication processor may be configured to transmit, to the first frequency synthesizing circuit, a first parameter indicating a frequency of the second electronic signal, and changing based on a first preset frequency interval according to a first preset period. The communication processor may be configured to transmit, to the second frequency synthesizing circuit, a second parameter indicating a frequency of the fourth electronic signal based on a frequency of a second clock signal, and changing based on a second preset frequency interval different from the first preset frequency interval.

A system for determining a communication mode utilized by a transmitting node to transmit a data packet in a mesh network is provided. For example, a receiving node operates in a base communication mode to detect a pilot p of a data packet. The pilot prefix contains a signal with a predetermined frequency. In response to determining that the pilot prefix is detected, the receiving node detects a communication mode used to transmit the data packet based on preamble signals that are contained in a preamble of the data packet and are received after the detected pilot prefix. Once the communication mode is detected, the receiving node receives and processes the remaining portion of the data packet using the detected communication mode.

A system for determining a communication mode utilized by a transmitting node to transmit a data packet in a mesh network is provided. For example, a receiving node operates in a base communication mode to detect a pilot p of a data packet. The pilot prefix contains a signal with a predetermined frequency. In response to determining that the pilot prefix is detected, the receiving node detects a communication mode used to transmit the data packet based on preamble signals that are contained in a preamble of the data packet and are received after the detected pilot prefix. Once the communication mode is detected, the receiving node receives and processes the remaining portion of the data packet using the detected communication mode.

A method for modulating data for transmission within a communication system. The method includes establishing a time-frequency shifting matrix of dimension N×N, wherein N is greater than one. The method further includes combining the time-frequency shifting matrix with a data frame to provide an intermediate data frame. A transformed data matrix is provided by permuting elements of the intermediate data frame. A modulated signal is generated in accordance with elements of the transformed data matrix.

A method for modulating data for transmission within a communication system. The method includes establishing a time-frequency shifting matrix of dimension N×N, wherein N is greater than one. The method further includes combining the time-frequency shifting matrix with a data frame to provide an intermediate data frame. A transformed data matrix is provided by permuting elements of the intermediate data frame. A modulated signal is generated in accordance with elements of the transformed data matrix.

A method and apparatus for modulating/demodulating an FSK signal capable of overcoming a trade-off relationship between a modulation index and a spectral efficiency are disclosed. An apparatus for modulating/demodulating a frequency deviation keying (FSK) signal includes a channel selection-modulator, a phase locked loop, and an output unit. The channel selection-modulator modulates an FSK signal by setting a frequency channel to be used. The phase locked loop generates a desired output frequency ‘fout’ compared to a reference frequency ‘f.sub.REF’ by adjusting a frequency division ratio (N+n) with respect to a frequency of the modulated FSK signal. The output unit amplifies the FSK signal having the generated output frequency ‘fout’ and radiating the amplified FSK signal through an antenna. Here, each of the frequency channels is divided into two or more tones, and different frequency channels are allocated between the tones divided into two or more tones.