Abstract: A method for communication includes receiving a composite signal, which carries data at a first data rate and includes multiple sub-signals that are interleaved in a time domain and are separated by boundary indicators. The received composite signal is demultiplexed into the sub-signals by automatically detecting the boundary indicators between the sub-signals in the composite signal. The sub-signals are demodulated using multiple respective demodulators operating at second data rates that are lower than the first data rate so as to generate respective output data streams. The output data streams are combined so as to reconstruct the data at the first data rate.

Abstract: A communication receiver includes a front end, which is arranged to receive a Radio Frequency (RF) signal, which includes modulated symbols carrying data that have been encoded by a block Forward Error Correction (FEC) code. The front end converts the RF signal to a sequence of soft received symbols, wherein the soft received symbols are subject to distortion by at least first and second noise components having respective at least first and second statistical distributions. A metric calculation unit is arranged to process the soft received symbols so as to extract parameters indicative of the at least first and second statistical distributions, and to compute FEC metrics based on the extracted parameters. A FEC decoder is arranged to accept the FEC metrics as input, and to process the metrics in an iterative FEC decoding process so as to decode the FEC code and reconstruct the data.

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 communication receiver includes a front end, which is arranged to receive a Radio Frequency (RF) signal, which includes modulated symbols carrying data that have been encoded by a block Forward Error Correction (FEC) code. The front end converts the RF signal to a sequence of soft received symbols, wherein the soft received symbols are subject to distortion by at least first and second noise components having respective at least first and second statistical distributions. A metric calculation unit is arranged to process the soft received symbols so as to extract parameters indicative of the at least first and second statistical distributions, and to compute FEC metrics based on the extracted parameters. A FEC decoder is arranged to accept the FEC metrics as input, and to process the metrics in an iterative FEC decoding process so as to decode the FEC code and reconstruct the data.

Abstract: A method for communication includes receiving first and second data frames over first and second communication links, respectively, the first and second data frames containing respective first and second replicas of data, which has been encoded with a Forward Error Correction (FEC) code. The FEC code in the received first and second data frames is decoded, and respective first and second soft quality ranks of the first and second data frames are computed based on the decoded FEC code. One of the first and second replicas of the data are selected based on the first and second soft quality ranks. The selected one of the first and second replicas of the data is provided as output.

Abstract: A method for communication includes receiving a signal, which carries data bits and is distorted by multiple impairments including one or more frequency offsets and one or more In-phase/Quadrature (I/Q) imbalances. A corrected signal is produced by applying to the received signal a sequence of corrections to compensate for the impairments. The sequence includes a first and a third correction of one correction type and a second correction of another correction type intervening between the first and third corrections in the sequence, the correction types consisting of frequency offset corrections and I/Q imbalance corrections. The data bits are extracted from the corrected signal.

Abstract: A frequency conversion apparatus includes a frequency generation circuit, which is based on a first semiconductor material having a first elemental composition and is coupled to generate one or more Local Oscillator (LO) signals. The apparatus further includes a conversion circuit, which is based on a second semiconductor material having a second elemental composition different from the first elemental composition. The conversion circuit is coupled to accept an input signal in a first frequency range and to convert the input signal to an output signal in a second frequency range by mixing the input signal with the one or more LO signals.

Abstract: A method for signal conversion includes generating a complex digital signal, which includes digital In-phase (I) and Quadrature (Q) components, for conversion into respective analog I and Q components by first and second Digital-to-Analog Converters (DACs). A distortion generated by the DACS in the analog I and Q components is reduced by applying a phase rotation to the complex digital signal. After applying the phase rotation, the digital I and Q components of the complex digital signal are converted into the respective analog I and Q components using the first and second DACs.

Abstract: A configurable frequency conversion device includes an up-converter, which is arranged to convert an input transmit signal to an interim transmit signal at an intermediate transmit frequency and to convert the interim transmit signal to an output transmit signal at an output frequency. A down-converter is arranged to convert an input receive signal at an input frequency to an interim receive signal at an intermediate receive frequency and to convert the interim receive signal to an output receive signal. Local Oscillator (LO) generation circuitry is arranged to generate multiple LO signals having respective LO frequencies and is coupled to drive the up- and down-converter with the LO signals, and is externally configurable to modify one or more of the LO frequencies so as to modify any of the output frequency, the input frequency, and a separation between the output and input frequencies without changing the intermediate receive and transmit frequencies.

Abstract: A receiver includes a front end, an up-converter and an interface. The front end is configured to down-convert a first Radio Frequency (RF) signal at a first frequency, so as to produce a second signal at a second frequency, lower than the first frequency. The up-converter is configured to up-convert the second signal to produce a third Intermediate Frequency (IF) signal at a third frequency, higher than the second frequency. The interface is configured to transmit the third signal over a cable for remote demodulation.

Abstract: A frequency conversion system includes a mixer, which is coupled to mix an input signal with a Local Oscillator (LO) signal, so as to produce an output signal. Control circuitry is configured to adjust an actual level of the LO signal provided to the mixer, so as to maintain the actual level substantially constant. A nulling signal generator is coupled to inject a nulling signal into the input signal prior to mixing with the LO signal adjusted by the control circuitry.

Abstract: A signal conversion apparatus includes first and second input ports and first and second output ports. A first splitter is coupled to convert a first single-ended signal received on the first input port into a differential signal including first and second opposite-phase components, and to provide the first and second opposite-phase components respectively on the first and second output ports. A second splitter is separate from the first splitter and is coupled to convert a second single-ended signal received on the second input port into a common-mode signal including first and second in-phase components, and to provide the first and second in-phase components respectively on the first and second output ports together with the first and second opposite-phase components.

Abstract: A communication terminal includes first and second antennas for respectively communicating with first and second remote terminals and a single up-converter that is arranged to up-convert an input signal to produce an RF transmit signal. The communication terminal further includes a switching circuit, which is arranged to couple the single up-converter to the first antenna in order to transmit the RF transmit signal to the first remote terminal during first time intervals, and to couple the single up-converter to the second antenna in order to transmit the RF transmit signal to the second remote terminal during second time intervals, which do not overlap the first time intervals.

Abstract: A method for communication includes sending first data over a first communication link to a destination communication system at a first data rate, which can be varied. Second data, including at least a portion of the first data, is sent over a second communication link from the source communication system to the destination communication system at a second data rate, which can be varied. First and second data rates of the respective first and second communication links are dynamically set. At least the portion of the first data is selectively extracted from one of the first and second data at the destination communication system. In some embodiments, the first data equals the second data, and the data is extracted without data loss.

Abstract: A method for communication includes accepting input data from two or more data sources, one or more of which include continuous synchronous tributaries, for transmission over a wireless communication link having a variable data rate. Relative priorities are assigned to the respective data sources. A currently-available data rate of the communication link is determined. The input data accepted from the data sources is multiplexed to produce a composite data stream. The input data of at least one of the tributaries is selectively omitted from the composite data stream based on the respective relative priorities, in order to match the data rate of the composite data stream to the currently-available data rate of the communication link. The composite data stream is transmitted over the communication link.

Abstract: A transmitter includes an up-converter and a modular receptable. The up-converter is coupled to convert an input signal into a Radio Frequency (RF) signal having an output frequency, and is configurable to adjust the output frequency over a frequency range containing multiple sub-bands. The modular receptacle includes a first interconnection adapter coupled to the up-converter and a second interconnection adapter for coupling to an antenna. The receptable is configured to receive between the first and second interconnection adapters a Power Amplifier (PA), which is selected from a group of power amplifiers each covering a respective sub-band in the frequency range.

Abstract: A method for communication using a modulation scheme defined in a signal space includes determining demodulation confidence levels at a plurality of points distributed over the signal space. Weights are assigned to the respective points responsively to the demodulation confidence levels. A signal is received and demodulated using an adaptive loop so as to derive a corresponding signal point in the signal space. The adaptive loop is adjusted responsively to a weight assigned to the derived signal point.

Abstract: A method for communication includes transmitting data from a transmitter to a receiver using Adaptive Coding and Modulation (ACM). The data rate is set by selecting, based on feedback, an ACM profile defining a Forward Error Correction code and a modulation scheme. Upon detecting that the feedback is unusable, an operation of the transmitter is changed independently of the feedback. In another method, data is exchanged over two opposite directions of a bidirectional link that uses ACM by communicating using two ACM profiles. A joint constraint is defined on the two directions. The two ACM profiles are set based on first and second measured reception quality metrics of the two link directions, to meet the joint constraint. In yet another method, a subset of the ACM profiles is temporarily disabled, and the data is transmitted using only the ACM profiles that are not disabled.

Abstract: A method for communication includes transmitting data from a transmitter to a receiver using Adaptive Coding and Modulation (ACM). The data rate is set by selecting, based on feedback, an ACM profile defining a Forward Error Correction code and a modulation scheme. Upon detecting that the feedback is unusable, an operation of the transmitter is changed independently of the feedback. In another method, data is exchanged over two opposite directions of a bidirectional link that uses ACM by communicating using two ACM profiles. A joint constraint is defined on the two directions. The two ACM profiles are set based on first and second measured reception quality metrics of the two link directions, to meet the joint constraint. In yet another method, a subset of the ACM profiles is temporarily disabled, and the data is transmitted using only the ACM profiles that are not disabled.

Abstract: A method for communication over a communication link, which includes a transmitter and a receiver, includes transmitting and receiving data, which is encoded using a specified forward error correction (FEC) code, modulated using a specified modulation scheme and transmitted at a given power level. One or more parameters of the communication link are monitored. A condition, which is based on values of one or more of the parameters monitored at a plurality of historical time instants, is evaluated. At least one feature of the transmitted data, selected from a group of features consisting of the FEC code, the modulation scheme and the power level, is modified based on the condition.