A frequency-selective system that may be used as, or as part of, an add/drop multiplexer. An input signal is fed to a Mach-Zehnder interferometer configured to drop, or suppress, by destructive interference, a signal component in a first frequency band from among a plurality of frequency bands. One or more bandpass filters in one arm of the Mach-Zehnder interferometer suppress other frequencies, outside of the first frequency band, so that signals at these other frequencies are not suppressed by destructive interference and are present at the output of the Mach-Zehnder interferometer. A coupler connected after the output of the Mach-Zehnder interferometer adds, into the signal path, a replacement for the dropped signal.

One example includes a troposcatter communication terminal. The terminal includes an antenna comprising a plurality of communication ports that extend from a rear side of the antenna to a front side of the antenna. The terminal also includes a positioner mechanically coupled to the antenna and being configured to mechanically control positioning of the antenna. The terminal further includes an electronics package mechanically coupled to the rear side of the antenna. The electronics package includes a troposcatter radio communicatively coupled to the antenna via the plurality of communications ports to transmit and receive troposcatter communication signals via the plurality of communication ports at the front side of the antenna.

One example includes a troposcatter communication terminal. The terminal includes an antenna comprising a plurality of communication ports that extend from a rear side of the antenna to a front side of the antenna. The terminal also includes a positioner mechanically coupled to the antenna and being configured to mechanically control positioning of the antenna. The terminal further includes an electronics package mechanically coupled to the rear side of the antenna. The electronics package includes a troposcatter radio communicatively coupled to the antenna via the plurality of communications ports to transmit and receive troposcatter communication signals via the plurality of communication ports at the front side of the antenna.

Systems and methods for OFDM channelization are provided that allow for the coexistence of sub-band channels and diversity channels. Methods of defining diversity sub-channels and sub-band sub-channels are provided and systematic channel definition and labeling schemes are provided.

Systems and methods for OFDM channelization are provided that allow for the coexistence of sub-band channels and diversity channels. Methods of defining diversity sub-channels and sub-band sub-channels are provided and systematic channel definition and labeling schemes are provided.

Transmission quality is improved in an environment in which direct waves dominate in a transmission method for transmitting a plurality of modulated signals from a plurality of antennas at the same time. All data symbols used in data transmission of a modulated signal are precoded by hopping between precoding matrices so that the precoding matrix used to precode each data symbol and the precoding matrices used to precode data symbols that are adjacent to the data symbol in the frequency domain and the time domain all differ. A modulated signal with such data symbols arranged therein is transmitted.

Transmission quality is improved in an environment in which direct waves dominate in a transmission method for transmitting a plurality of modulated signals from a plurality of antennas at the same time. All data symbols used in data transmission of a modulated signal are precoded by hopping between precoding matrices so that the precoding matrix used to precode each data symbol and the precoding matrices used to precode data symbols that are adjacent to the data symbol in the frequency domain and the time domain all differ. A modulated signal with such data symbols arranged therein is transmitted.

A method of wireless communication includes, in response to a trigger event detected at a first base station, performing, by the first base station, a scan of a plurality of frequencies for a synchronization signal block (SSB) transmission from a second base station. The plurality of frequencies correspond to a plurality of global synchronization channel numbers (GSCNs) associated with the first base station and the second base station. The first base station is associated with a first coverage area that is at least partially within a second coverage area associated with the second base station. The method further includes transmitting, by the first base station, one or more SSBs having an SSB configuration that is based on a result of the scan.

A wireless communication system according to the present invention includes a transmission control device and a reception control device configured to communicate with each other via at least one wireless link established in a wireless network, the transmission control device including a composite signal generation unit configured to select at least one signal from a predetermined number of signals to generate a composite signal and a multipath control unit configured to transmit the composite signal via the at least one wireless link, the reception control device including a multipath control unit configured to receive the composite signal from the at least one wireless link and a signal recovery unit configured to accumulate the received composite signal and to recover the predetermined number of signals from the predetermined number or more of the composite signals, the predetermined number being 1 or more.

An apparatus is provided for generating a transmission wave. The apparatus includes a plurality of antennas and a plurality of signal generators. The plurality of antennas has polarization diversity. The plurality of signal generators are each coupled to one of the antennas and configured to generate a continuous twisted wave by driving each of the antennas using independent, coordinated, and distinct sinusoidal waves, and having a twist frequency and a carrier frequency, the twist frequency lower than the carrier frequency. A method is also provided.