To appropriately select a beam used in communication in an environment in which massive-MIMO beamforming is performed, there is provided a base station including: a communication unit configured to form multiple beams and perform communication with a terminal apparatus; and a control unit configured to transmit, to the terminal apparatus, first identification information of a group that is used in communication with the terminal apparatus among the first identification information allocated to groups each of which includes multiple beams to be formed.

A transmission apparatus includes a plurality of orthogonal frequency division multiplexing (OFDM) modulation signal generators, which generate a first OFDM modulation signal and a second OFDM modulation signal. The transmission apparatus also includes a transmitter that transmits the first OFDM modulation signal from a first antenna and the second OFDM modulation signal from a second antenna, in an identical frequency band. A reception apparatus is provided, which includes a plurality of antennas that receive a plurality of OFDM modulation signals; a plurality of OFDM demodulators that transform the plurality of OFDM modulation signals to a plurality of reception signals using Fourier transform; an estimator that outputs a distortion estimation signal using one or more symbols for demodulation included in the plurality of reception signals; and a demodulator that compensates for distortion of the reception signals using the distortion estimation signal and demodulates a data symbol included in the reception signals.

As may be used in connection with frequency-modulated (FM) radio systems and receivers processing FM broadcast transmissions, exemplary aspects are directed to a method may be performed by the receiver circuitry to receive FM broadcast signaling within a particular bandwidth for which a plurality of target channels are to have a specified channel spacing. The method may include: assessing detected energy for a first adjacent channel having the specified channel spacing and having a frequency immediately adjacent to a targeted one of the plurality of target channels; and discerning whether the detected energy is associated with ultra-sonic energy in detected modulation energy (e.g., ultra-sonic noise in an MPX signal), and/or is associated with modulation energy (e.g., due to over-modulation) from a second adjacent channel also having such specified channel spacing.

A technique, including transmitting data and/or control information; and transmitting common phase error and/or inter carrier interference correction reference signal, wherein said common phase error and/or inter carrier interference correction reference signal occupies a variable amount of radio resources.

A radio transmission apparatus determines information indicative of an estimated communications channel condition and generates a single modulation signal or a plurality of modulation signals based on the estimated communications channel condition information. The single modulation signal is transmitted from a first antenna of a plurality of antenna or the plurality of modulation signals are transmitted from the first antenna and at least a second antenna of the plurality of antenna. The plurality of modulation signals include different information from each other and are transmitted over an identical frequency band and at an identical temporal point. The single modulation signal and the plurality of modulation signals contain parameter information indicating a number of modulation signals transmitted at the same time.

Systems and methods for mitigation of cross channel interference are disclosed in which the TDD configuration of a potential cross channel interference source is detected by received signals within the network with which the source interferes. The TDD configuration is then used to synchronize the transmissions from the network with which the source interferes to reduce the interference. In addition, interference is mitigated by providing adaptive guard bands based on results of a radio frequency environmental survey and/or coaxing an interfering user to another channel. Sub-channels can be assigned based on the results of the radio frequency environmental survey and Quality of Service requirements for traffic flows.

In one example, a communications circuit processes an amplitude modulated signal by using a first circuit having signal paths to process an amplitude modulated signal as represented by an in-phase component and by a quadrature component, and by using a second circuit to discern random noise pulses from the quadrature component of the amplitude modulated signal. In response, the second circuit generates an estimate of overall noise representing the random noise pulses in the amplitude modulated signal. In the above and more specific examples, the random noise pulses may appear as pulses which overlap with, in terms of time and bandwidth of frequency spectrum, information of the amplitude modulated signal, and the first and second circuits may be part of an RF radio receiving the amplitude modulated signal from an antenna.

A packet detecting method includes receiving the wireless signal, generating a local characteristic sequence, acquiring a first cross-correlation result between the wireless signal and the local characteristic sequence, determining if a packet format of the wireless signal is a target packet format according to the first correlation result, generating at least one interference characteristic sequence according to the local characteristic sequence, a signal sampling frequency, and at least one working frequency difference, acquiring a second cross-correlation result between the wireless signal and the at least one interference characteristic sequence, and detecting a center frequency of the wireless signal for determining if a packet of the wireless signal is transmitted through a target channel according to the first correlation result and the second correlation result. The at least one interference characteristic sequence corresponds to at least one interference frequency.

A base station, a communication system and a time synchronization method between base stations are provided, which are capable of performing a time synchronization with another base station using a downlink signal of the other base station cell in which the own cell is located, without stopping transmission of the own base station even during operation. A base station 20 receives a downlink signal 255 that includes a downlink signal 11 including a synchronization signal transmitted from the other base station 10 and a downlink wraparound signal 22 transmitted from own base station 20, removes an interference of the wraparound signal from the downlink received signal, with respect to a predetermined subframe in which the downlink wraparound signal from own base station 20 interferes with the synchronization signal of the base station 10, among subframes of the downlink signal including the synchronization signal of the base station 10, performs a time synchronization processing with the base station 10 by detecting a synchronization signal timing of the base station 10 based on the downlink received signal from which the interference of wraparound signal is removed.

Described are methods for dealing with phase noise, e.g., common phase error and/or inter-carrier interference, in communication systems, and apparatuses for the same. A method can include at least: transmitting one or more reference signals (in-band signals within a channel); and mapping the reference signals to radio resources in the channel for transmission of the reference signals. An amount of the radio resources may depend on, e.g., information about a modulation and coding scheme used for transmission. An associated method can include at least: receiving one or more reference signals, and mapping the reference signals to radio resources in the channel for reception of the reference signals; receiving information about a modulation and coding scheme to be used, an amount of the radio resources depending on, e.g., information about the modulation and coding scheme used for reception; and using the reference signals to compensate for phase noise.