A single channel receiver includes an input terminal that receives an analog input signal, a mixer that down-mixes the analog input signal by use of a phase- and/or frequency-corrected oscillator frequency signal and shifts complex-valued information contained in the analog input signal to the real part (or alternatively to the imaginary part) to obtain an intermediate real-valued analog signal, an analog-to-digital-converter that converts the intermediate analog signal into an intermediate digital signal, a demodulator that demodulates the intermediate digital signal into a digital output signal, a phase tracking loop that detects zero-crossings in the intermediate digital signal to obtain phase error information representing a phase error in the intermediate digital signal, and an oscillator that generates the phase- and/or frequency-corrected oscillator frequency signal by compensating the phase and/or frequency error in the intermediate digital signal by correcting the phase of the oscillator frequency signal with the phase error information.

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.

A modulator operable to control an oscillator is described. The modulator can include a memory that stores oscillator control values and a bit streaming block. The bit streaming block can generate a bit stream based on the oscillator control values and transmit the bit stream to the oscillator to control an oscillation frequency of the oscillator. The modulator can also include a bit streaming loader (BSL). The BSL can receive one or more of the oscillator control values from the memory, generate one or more corresponding bit values based on the one or more of the oscillator control values, and provide the one or more bit values to the bit streaming block. The bit streaming block can then generate the bit stream based the one or more bit values generated by the BSL.

Provided herein are apparatus and methods for wideband receivers. In certain configurations, a radio frequency (RF) communication system includes two or more receiver slices that operate in parallel with one another to process an RF input signal. The receiver slices generate digital signals by processing different sub-bands of the RF input signal. For example, the RF communication system can include a first receiver slice that processes a first sub-band of the RF input signal and that generates a first digital signal representing the first sub-band, and a second receiver slice that processes a second sub-band of the RF input signal and generates a second digital signal representing the second sub-band. The RF communication system further includes a clock generation circuit that generates one or more clock signals to control timing of the receiver slices, and a sub-band processing circuit that processes the digital signals from the receiver slices.

To actualize frequency synchronization with each of radio communication systems while suppressing increase in circuit scale of a user terminal in an environment in which the user terminal concurrently communicates with a plurality of radio communication systems with different frequencies, a radio base station of the present invention is a radio base station for forming a narrow-area cell to communicate with a user terminal in a radio communication system where the narrow-area cell is provided inside a wide-area cell, and has a carrier frequency synthesizer that generates a carrier frequency of the narrow-area cell based on a wide-area radio signal transmitted from a radio base station for forming the wide-area cell, and a sampling frequency synthesizer that generates a sampling frequency of a baseband signal of the narrow-area cell based on the wide-area radio signal.

Systems and methods for transpositional modulation and demodulation are provided. One such method for generating a signal includes the steps of providing a look-up table having a plurality of quarter-cycle waveforms, each of said quarter-cycle waveforms associated with a respective input level; receiving an input signal; and outputting quarter-cycle waveforms associated with levels of the received input signal. Systems for transpositional modulation are also provided. One such system for generating a signal includes a look-up table having a plurality of quarter-cycle waveforms. Each of the quarter-cycle waveforms are associated with a respective input level, and the look-up table is configured to receive an input signal, and output quarter-cycle waveforms associated with levels of the received input signal.

Methods, systems, and devices are described for mitigating an unwanted increase in a coding rate of a wireless communication signal. A plurality of symbols including a transmitted codeword is received. The plurality of symbols including a first group of data symbols with a first modulation and coding scheme and a second group of data modulated pilot symbols with a second modulation and coding scheme. Applicable demodulation schemes are adaptively switched for each group of the plurality of symbols. The second group of data modulated pilot symbols are used in lieu of pilot symbols. The second modulation and coding scheme is a more reliable modulation and coding scheme than the first modulation and coding scheme.

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.

A receiver comprising: a processing module configured to: receive a first portion of a packet of received signalling from a first antenna; receive a carrier estimate signal; adjust the first portion based on the carrier estimate signal and correlate the signal with an expected code sequence to provide a first correlated signal; a tracking module configured to: receive the first correlated signal and update the carrier estimate signal, wherein the processing module is further configured to: receive a second portion of the packet from a second antenna; adjust the second portion based on the carrier estimate signal and correlate the signal to provide a second correlated signal, and wherein the receive path further comprises a phase calculation module configured to: receive the first and second correlated signals and determine a respective first and second carrier phase and an angle of arrival of the received signalling.

Accordingly, there are disclosed herein receivers and receiving methods that provide a graceful transition from PAM2 to PAM4 signaling. One illustrative method includes: negotiating a link speed having PAM4 signaling; performing adaption of at least one gain or filter coefficient during PAM2 signaling; switching to PAM4 detection before receiving PAM4 signaling; disabling said adaptation before said switching to PAM4 detection; detecting PAM4 signaling using at least one statistic of detected PAM4 symbols; and enabling said adaptation after PAM4 signaling is detected. Another illustrative method includes: negotiating a link speed having PAM4 signaling; adapting at least one of gain and filter coefficients during PAM2 signaling; monitoring for a change in at least one signal characteristic while performing PAM2 detection; and transitioning to PAM4 detection after detecting said change.