Apparatus and methods related to multipath bandpass filters with passband notches are provided herein. In certain configurations, a multipath bandpass filter includes multiple filter circuit branches or paths that are electrically connected in parallel with one another between an input terminal and an output terminal. The input terminal receives an input signal, and each filter circuit branch includes a downconverter that downconverts the input signal to generate a downconverted signal, a filter network that generates a filtered signal by filtering the downconverted signal, and an upconverter that upconverts the filtered signal to generate a branch output signal. The filter network includes at least one low pass filter and at least one notch filter to provide a passband with in-band notches. The branch output signals from the filter circuit branches are combined to generate an output signal at the output terminal.

A data bus interface may include a history buffer and a serializer. The history buffer may store bits representing a history of data recently transmitted on the data bus. The serializer may be configured to modify an input bit sequence containing original bits by interspersing padding bits with the original bits to suppress noise at one or more target frequencies. The serializer may output the modified input bit sequence on the data bus. Each padding bit of the plurality of padding bits may be generated based on values of at least two bits stored in the history buffer.

Multipath filters are provided herein. In certain configurations, a multipath filter includes multiple filter paths or circuit branches that are electrically connected in parallel with one another between an input terminal and an output terminal. The input terminal receives an input signal, and each filter circuit branch includes a double-in double-switched (DIDS) downconverter that downconverts the input signal with two different clock signal phases to generate a downconverted signal. Each filter circuit branch further includes a filter network that generates a filtered signal by filtering the downconverted signal and an upconverter that upconverts the filtered signal to generate a branch output signal. Additionally, the branch output signals from the filter circuit branches are combined to generate an output signal at the output terminal.

Systems and methods directed towards reducing noise introduced into a signal when processing the signal are discussed herein. In embodiments a signal may initially be split by a multiplexer into two or more frequency bands. Each of the frequency bands can then be forwarded through an assigned channel. One or more channels may include an amplifier to independently boost the signal band assigned to that channel prior to a noise source within the assigned channel. This results in boosting the signal band relative to noise introduced by the noise source. In some embodiments, a filter may also be implemented in one or more of the channels to remove noise from the channel that is outside the bandwidth of the signal band assigned to that channel. Additional embodiments may be described and/or claimed herein.

A method for reducing the peak factor of a signal transmitted in a frequency band comprising several channels, the signal using a plurality of channels in the band comprises: a step of clipping the signal, a step of subtracting the clipped signal from the signal, so as to obtain a peak signal, a step of filtering the peak signal with the aid of a multichannel filter configured to comply with a predetermined spectral mask for each of the channels used by the signal, and a step of subtracting the filtered peak signal from the signal. A device for emitting a multichannel signal implementing the method for reducing the peak factor is also provided.

A communication apparatus has a receiver that is capable of receiving an alternating phase signal and a tuned circuit whose input is adjusted to be capable of receiving the alternating phase signal. The communication apparatus can be used with both wireless and wired communication links and provide enable faster data rates, greater immunity to noise, increased bandwidth/spectrum efficiency and/or other benefits. Applications include but are not limited to: cell phones, smartphones (e.g., iPhone, BlackBerry, etc.), wireless Internet, local area networks (e.g., WiFi type applications), wide area networks (e.g., WiMAX type applications), personal digital assistants, computers, Internet service providers and communications satellites.

A transmission system includes a first transponder including a first I/Q modulator, and a second transponder including a second I/Q modulator, and configured to communicate with the first transponder using a frequency modulation scheme, wherein the first transponder is configured to set a first phase rotation mode in a first state for first light signal output from the first I/Q modulator, and transmit, to the second transponder, a first command to specify a second phase rotation mode for second light signal output from the second I/Q modulator, and the second transponder is configured to set, in response to the first command, the second phase rotation mode in a state specified by the first command.

The present disclosure relates to a method for transmitting and receiving a beamformed data transmission transmitted from a radio base station to a user equipment over an unlicensed band. The data transmission is transmitted by the radio base station within one or more resource blocks of a subframe, each resource block being composed of a plurality of resource elements. The beamformed data transmission is generated by the radio base station by 1) applying a first precoding for generating a beam directionality towards the user equipment to a subset of all the resource elements used for transmitting the data transmission in the subframe, and 2) applying a second precoding, different from the first precoding, to the remaining resource elements used for transmitting the data transmission in the subframe so as to achieve a radiation pattern different from the beam directionality towards the user equipment.

Embodiments of this application provide a signal transmission method and a communication apparatus in a multi-waveform scenario, and are applied to a scenario in which a single-carrier waveform and a multi-carrier waveform coexist. In this method, a network device indicates, via first indication information, a terminal device to transmit a signal by using transmission parameters corresponding to the first indication information, so that the terminal device transmits the signal by using the specified transmission parameters. Transmission parameters includes at least two of a transmission bandwidth, an extended bandwidth, or a total bandwidth. According to the embodiments of this application, a transmit end may perform sending by using the single-carrier waveform, and a receive end may perform receiving by using the multi-carrier waveform; or a transmit end may perform sending by using the multi-carrier waveform, and a receive end may perform receiving by using the single-carrier waveform.

A communication device, including a receiver configured to receive a signal from a transmitter, the signal including a plurality of data symbols; and at least one processor configured to: obtain a channel estimate and an estimated carrier frequency offset based on a result of an interference detection indicating whether interference is detected in the plurality of data symbols, obtain a data symbol of the plurality of data symbols, obtain a compensated data symbol corresponding to the data symbol based on the estimated carrier frequency offset, obtain an equalized compensated data symbol by performing channel equalization on the compensated data symbol based on the channel estimate, and demodulate and decode the equalized compensated data symbol to obtain decoded data.