Abstract: A communication system includes first and second transmitters, which are coupled to transmit respective first and second Radio Frequency (RF) signals carrying first and second data over a wireless communication channel. The transmitters are coupled to select an operational mode from a group of operational modes and to operate in the selected operational mode. The group of the operational modes includes at least two of a protection mode, wherein the second transmitter serves as backup to the first transmitter, a spatial multiplexing mode, in which the first data is different from the second data and the first and second transmitters transmit simultaneously, and a beam-forming mode, in which the first data is identical to the second data, the second RF signal includes a phase-shifted replica of the first RF signal, and the first and second transmitters transmit simultaneously.

Abstract: A method and system is disclosed for precoding in a two transmit antenna MIMO system, for example, a wireless backhaul network. The method only uses the first column of the 2×2 precoder as the feedback information. When the feedback information is available to the transmitter, the transmitter performs an interpolation and reconstruction procedure to obtain the precoder matrix for each subcarrier. The method offers no significant loss in performance, with reduced computational complexity and feedback overhead compared to conventional known matrix representation methods.

Abstract: A communication system includes multiple communication nodes and a processor. The communication nodes are configured to communicate over a tropospheric scattering channel. The processor is configured to communicate with the communication nodes over a secondary communication network, different from the tropospheric scattering channel, so as to control communication of the communication nodes over the tropospheric scattering channel.

Abstract: A method and system is disclosed for precoding in a two transmit antenna MIMO system, for example, a wireless backhaul network. The method only uses the first column of the 2×2 precoder as the feedback information. When the feedback information is available to the transmitter, the transmitter performs an interpolation and reconstruction procedure to obtain the precoder matrix for each subcarrier. The method offers no significant loss in performance, with reduced computational complexity and feedback overhead compared to conventional known matrix representation methods.

Abstract: A communication system includes multiple communication nodes and a processor. The communication nodes are configured to communicate over a tropospheric scattering channel. The processor is configured to communicate with the communication nodes over a secondary communication network, different from the tropospheric scattering channel, so as to control communication of the communication nodes over the tropospheric scattering channel.

Abstract: Octagonal non-rectangular Quadrature Amplitude Modulation (QAM) is disclosed. Grid points from a uniform rectangular grid, which includes points that have equal horizontal and vertical spacing, are selected to form a non-rectangular octagonal grid that approximates an octagonal shape. QAM symbols are mapped to respective grid points in the non-rectangular octagonal grid to form a non-rectangular octagonal QAM constellation that also approximates the octagonal shape. Input signals can then be modulated using the non-rectangular octagonal QAM constellation.

Abstract: A communication terminal includes first and second transmitters, which are coupled to produce respective first and second Radio Frequency (RF) signals that are phase-shifted with respect to one another by a beamforming phase offset, and to transmit the RF signals toward a remote communication terminal. The terminal includes a reception subsystem including first and second receivers and a phase correction unit. The first and second receivers are respectively coupled to receive third and fourth RF signals from the remote communication terminal. The phase correction unit is coupled to produce, responsively to the third and fourth RF signals, a phase correction for correcting an error component in the beamforming phase offset.

Abstract: A communication system includes first and second transmitters, which are coupled to transmit respective first and second Radio Frequency (RF) signals carrying first and second data over a wireless communication channel. The transmitters are coupled to select an operational mode from a group of operational modes and to operate in the selected operational mode. The group of the operational modes includes at least two of a protection mode, wherein the second transmitter serves as backup to the first transmitter, a spatial multiplexing mode, in which the first data is different from the second data and the first and second transmitters transmit simultaneously, and a beam-forming mode, in which the first data is identical to the second data, the second RE signal includes a phase-shifted replica of the first RE signal, and the first and second transmitters transmit simultaneously.

Abstract: A communication terminal includes first and second transmitters, which are coupled to produce respective first and second Radio Frequency (RF) signals that are phase-shifted with respect to one another by a beamforming phase offset, and to transmit the RF signals toward a remote communication terminal. The terminal includes a reception subsystem including first and second receivers and a phase correction unit. The first and second receivers are respectively coupled to receive third and fourth RF signals from the remote communication terminal. The phase correction unit is coupled to produce, responsively to the third and fourth RF signals, a phase correction for correcting an error component in the beamforming phase offset.

Abstract: A communication terminal includes first and second transmitters, which are coupled to produce respective first and second Radio Frequency (RF) signals that are phase-shifted with respect to one another by a beamforming phase offset, and to transmit the RF signals toward a remote communication terminal. The terminal includes a reception subsystem including first and second receivers and a phase correction unit. The first and second receivers are respectively coupled to receive third and fourth RF signals from the remote communication terminal. The phase correction unit is coupled to produce, responsively to the third and fourth RF signals, a phase correction for correcting an error component in the beamforming phase offset.

Abstract: A receiver includes an input circuit, which is coupled to at least one antenna so as to receive, process and digitize first and second signals, thus generating first and second streams of input samples. An interference cancellation circuit in the receiver includes first and second adaptive filters, which are respectively coupled to filter the first and second streams of input samples using respective first and second coefficients to generate respective first and second filter outputs. A phase rotator is adapted to apply a variable phase shift compensating for a phase deviation between the first and second signals, the phase rotator having at least one configuration parameter. A control module is operative to estimate signal characteristics of the interference cancellation circuit and to set the at least one configuration parameter of the phase rotator responsively to the estimated signal characteristics.

Abstract: A method for communication includes receiving over a communication link data that has been encoded using a forward error correcting (FEC) code. The encoded data is decoded using an iterative decoding process, which produces metrics. A condition of the communication link is assessed responsively to the metrics.

Abstract: A communication terminal includes first and second transmitters, which are coupled to produce respective first and second Radio Frequency (RF) signals that are phase-shifted with respect to one another by a beamforming phase offset, and to transmit the RF signals toward a remote communication terminal. The terminal includes a reception subsystem including first and second receivers and a phase correction unit. The first and second receivers are respectively coupled to receive third and fourth RF signals from the remote communication terminal. The phase correction unit is coupled to produce, responsively to the third and fourth RF signals, a phase correction for correcting an error component in the beamforming phase offset.

Abstract: A method for antenna alignment includes defining a first link budget for wireless communication between first and second communication systems via respective first and second antennas in a normal operational mode in which a main lobe of the first antenna points toward the second antenna. The first antenna is aligned to point to the second antenna responsively to an alignment indication provided by communicating between the first and second communication systems in an alignment operational mode having a second link budget greater than the first link budget.

Abstract: A method for antenna alignment includes defining a first link budget for wireless communication between first and second communication systems via respective first and second antennas in a normal operational mode in which a main lobe of the first antenna points toward the second antenna. The first antenna is aligned to point to the second antenna responsively to an alignment indication provided by communicating between the first and second communication systems in an alignment operational mode having a second link budget greater than the first link budget.

Abstract: A method for communication includes receiving over a communication link data that has been encoded using a forward error correcting (FEC) code. The encoded data is decoded using an iterative decoding process, which produces metrics. A condition of the communication link is assessed responsively to the metrics.

Abstract: A receiver includes an input circuit, which is coupled to at least one antenna so as to receive, process and digitize first and second signals, thus generating first and second streams of input samples. An interference cancellation circuit in the receiver includes first and second adaptive filters, which are respectively coupled to filter the first and second streams of input samples using respective first and second coefficients to generate respective first and second filter outputs. A phase rotator is adapted to apply a variable phase shift compensating for a phase deviation between the first and second signals, the phase rotator having at least one configuration parameter. A control module is operative to estimate signal characteristics of the interference cancellation circuit and to set the at least one configuration parameter of the phase rotator responsively to the estimated signal characteristics.