A radio frequency (RF) transmitter includes a set of input ports to receive baseband, a set of filter banks for each input port that includes a plurality of digital polyphase interpolation filters, and a set of oscillators banks, wherein each oscillator bank includes a plurality of polyphase Digital Direct Synthesizer (DDS) corresponding to the plurality of digital polyphase interpolation filters. The RF transmitter includes a set of mixer banks to mix corresponding sequences of samples of digital waveform, a parallel digital combiner to combine in-phase sequences of interpolated baseband phased samples, and a pulse encoder to modulate and encode the plurality of sequences of multiband upconverted samples. The RF transmitter converts a plurality of encoded multi-band signals into a RF bitstream and an E/O interface to convert the RF bitstream.

Processes and devices for finding signals within a frequency range include converting an analog input signal to a digital domain using an analog-to-digital converter to create a digital input signal. A first fast Fourier transform (FFT) converts the digital input signal to a frequency input signal, which is binned based on frequency and a threshold to create a binary filter. The digital input signal (from the analog-to-digital converter) is sorted into containers (e.g., using the Chinese remainder theorem) and then run through a second FFT to convert the digital input signal to a frequency intermediate signal. The frequency intermediate signal is sorted into bins and multiplied using the binary filter to create an output frequency signal.

A communication system includes a transmission station, a reception station, one or more relay stations configured to relay a first signal from the transmission station to the reception station without demodulating or decoding the first signal, and a controller. The controller is configured to acquire a first delay time and a first phase rotation amount to be provided to the first signal in relay by a first relay station so that one or more relay signals of the first signal arrive at the reception station at the same time and in the same phase after a first time length from a head of a slot in a radio frame and to cause the first relay station to provide the first delay time and the first phase rotation amount to the first signal.

A radio frequency (RF) transmitter includes a set of input ports to receive baseband, a set of filter banks for each input port that includes a plurality of digital polyphase interpolation filters, and a set of oscillators banks, wherein each oscillator bank includes a plurality of polyphase Digital Direct Synthesizer (DDS) corresponding to the plurality of digital polyphase interpolation filters. The RF transmitter includes a set of mixer banks to mix corresponding sequences of samples of digital waveform, a parallel digital combiner to combine in-phase sequences of interpolated baseband phased samples, and a pulse encoder to modulate and encode the plurality of sequences of multiband upconverted samples. The RF transmitter converts a plurality of encoded multi-band signals into a RF bitstream and an E/O interface to convert the RF bitstream.

Embodiments of this application provide a signal transmission method and apparatus, and the method includes: filtering a first time domain orthogonal frequency division multiplexing (OFDM) signal at each of M spatial transmission layers, where M is an integer greater than or equal to 1; performing spatial precoding on the filtered first time domain OFDM signal at each of the M spatial transmission layers, and mapping the filtered first time domain OFDM signal at each of the M spatial transmission layers to each of N.sub.t transmit antenna ports, where N.sub.t is an integer greater than or equal to M; and superposing and transmitting the first time domain OFDM signals that are at the M spatial transmission layers and that are mapped to all the N.sub.t transmit antenna ports.

A digital predistortion linearization method is provided for increasing the instantaneous or operational bandwidth for RF power amplifiers employed in wideband communication systems. Embodiments of the present invention provide a method of increasing DPD linearization bandwidth using a feedback filter integrated into existing digital platforms for multi-channel wideband wireless transmitters. An embodiment of the present invention utilizes a DPD feedback signal in conjunction with a low power band-pass filter in the DPD feedback path.

A 24 GHz band-pass filter includes a step impedance resonator, a first U-shape feeding portion, a second U-shape feeding portion, short-circuit stubs and open-circuit stubs. The step impedance resonator includes a first main portion, a second main portion, and a connection portion for connecting the main portions to each other. The first main portion and the second main portion are electrically connected to a first signal input/output port and a second signal input/output port. The first U-shape feeding portion is electrically connected between the first main portion and the first signal input/output port. The second U-shape feeding portion is electrically connected between the second main portion and the second signal input/output port. The short-circuit stubs are electrically connected to coupling segments of the step impedance resonator. The open-circuit stubs are electrically connected to the first U-shape feeding portion and the second U-shape feeding portion.

Methods and systems are provided for converting wideband signals. In an example system, a wideband signal that includes one or more narrowband signals may be received and handled, with the handling may include selecting a subset of signal processing circuits, from a plurality of signal processing circuits in the system, with the number of selected signal processing circuits being less than the total number of signal processing circuits in the system. Only the selected signal processing circuits are then enabled, such that all remaining signal processing circuits are not enabled. Signal processing adjustment may then be applied, via the subset of signal processing circuits, only to the one or more narrowband signals, such that a remainder of the wideband signal is not adjusted. The handling of the received wideband signal may include separating the one or more narrowband signals from the wideband signal.

Embodiments of this application provide a signal transmission method and apparatus, and the method includes: filtering a first time domain orthogonal frequency division multiplexing (OFDM) signal at each of M spatial transmission layers, where M is an integer greater than or equal to 1; performing spatial precoding on the filtered first time domain OFDM signal at each of the M spatial transmission layers, and mapping the filtered first time domain OFDM signal at each of the M spatial transmission layers to each of N.sub.t transmit antenna ports, where N.sub.t is an integer greater than or equal to M; and superposing and transmitting the first time domain OFDM signals that are at the M spatial transmission layers and that are mapped to all the N.sub.t transmit antenna ports.

A fully integrated power amplifier (PA) employing a transformer combiner with enhanced back-off efficiency includes a first PA to amplify a first radio frequency (RF) signal and a second PA to amplify a second RF signal. A first variable capacitor is coupled between differential output nodes of the first PA. A second variable capacitor is coupled between differential output nodes of the second PA. The differential outputs of the first PA and the second PA are coupled via respective first and second transformers to a load. Capacitance values associated with the first and second variable capacitors are dynamically adjustable based on an amplitude of the RF signal to achieve a desired power efficiency at an output power level.