Abstract: A system and method for controlling modulation. The system includes a plurality of modulators and a transmitting unit. The plurality of modulators decodes data from a data signal and also encodes the data into a clock signal. The transmitting unit transmits the encoded clock signal. According to the system and method disclosed herein, the present invention provides optimized coding efficiency while minimizing overall power consumption.

Abstract: An apparatus and a method for determining a multi-antenna transmission mode at a base station in a multi-antenna system are provided. The method for determining the multi-antenna transmission mode includes when using a Multiple Input Multiple Output (MIMO) transmission mode as a multi-antenna transmission mode, determining a reference set point; updating a set point for transmit power control of a terminal according to an error occurrence of a signal received from the terminal; determining whether a channel to the terminal is a channel for applying the MIMO transmission mode by comparing the updated set point with the reference set point; and when the channel to the terminal is not a channel for applying the MIMO transmission mode, changing the multi-antenna transmission mode to a fixed transmission mode.

Abstract: The present invention relates an apparatus and method of estimating a signal-to-noise ratio (SNR) of a received signal when the received signal has a timing offset. An apparatus for estimating a signal-to-noise ratio (SNR) according to an exemplary embodiment of the present invention includes a fast Fourier transform (FFT) unit that performs a fast Fourier transform on a received signal to convert the received signal into a frequency domain signal; a preamble selector that extracts a preamble from the frequency domain signal; a correlator that correlates the preamble to a preamble reference signal generated by a receiver to calculate a correlation value; an entire power estimator that calculates entire power; a noise power estimator that applies a differential demodulation method to the correlation value to remove a timing offset and calculate noise power; and an estimating unit that uses the entire power and the noise power to estimate the signal-to-noise ratio (SNR).

Abstract: In one implementation, a polar transmitter includes a digital signal processing component that processes baseband signals and provides a baseband data signal with amplitude values; and a digital pre-distortion component that receives the baseband data signal with amplitude values, compensates for jitter error in the baseband data signal with amplitude values, and provides an adjusted modulated signal.

Abstract: An apparatus and method for estimating a carrier-to-interference-and-noise ratio (CINR) of a received signal in an orthogonal frequency division multiplexing (OFDM) system are provided. A band-pass filter attenuates a signal region of the received signal and passes a signal in a noise region. A first power calculator calculates interference and noise power of the noise-region signal received from the band-pass filter. A second power calculator calculates total received power of the received signal. A ratio calculator calculates a CINR based on the interference and noise power, and the total received power.

Abstract: A method and system for digital spur cancellation may include removing a spur in a left channel minus right channel (L?R) baseband signal generated from a FM signal. The L?R baseband signal may be generated by demodulating a sub-carrier, for example, by using CORDIC algorithm, in a signal demodulated from the FM signal. An orthogonal signal may also be generated by demodulating a sub-carrier, for example, by using CORDIC algorithm, in a signal demodulated from the FM signal. The phase of the orthogonal signal may be further adjusted to introduce a substantially ?90° phase shift to spurs at a specific frequency. Accordingly, the spurs in the L?R baseband signal may be cancelled when the first L?R baseband signal is combined with the phase adjusted orthogonal signal.

Abstract: A system for detecting and correcting for spurious frequencies that may coincide in a bandwidth of interest in an RF metrology system. The system can (1) utilize a deterministic scheme to detect an interference by a spurious frequency and correct the distortion effect or (2) utilize a mixed signal processing architecture to avoid the occurrence of spurious frequency contamination. A detection scheme identifies the event of distortion and triggers either (a) a shift in the analog to digital convert sample rate or (b) a mathematical vector manipulation. The shift of the analog to digital convert sample rate moves an aliased image of the spurious frequency outside of the frequency of interest. The mathematical vector correction removes the distortion and restores the signal of interest.

Abstract: Systems and methodologies are described that facilitate employing downlink precoding based on uplink sounding channel measurement and channel reciprocity in time division duplex or time division multiplex systems. In particular, mechanism are provided that enable downlink precoding in situations where user equipment antenna configuration includes an unequal number of transmit chains and receive chains. A mobile device transmits modulated sounding reference signals on each antenna during a calibration stage. The mobile device then transmits non-modulated sounding reference signals during a normal mode. A base station utilizes the modulated and non-modulated sounding reference signals to restore a downlink channel estimate employed in downlink precoding.

Abstract: The present invention provides a method of windowing signals in a communication system. The method includes accessing at least one first signal associated with at least one of a plurality of orthogonal frequencies and applying a window function to the at least one first signal to form at least one second signal. The at least one second signal remains substantially orthogonal to signals associated with the plurality of orthogonal frequencies.

Abstract: In various embodiments of the present invention, optimal or near-optimal multidirectional context sets for a particular data-and/or-signal analysis or processing task are determined by selecting a maximum context size, generating a set of leaf nodes corresponding to those maximally sized contexts that occur in the data or signal to be processed or analyzed, and then building up and concurrently pruning, level by level, a multidirectional optimal context tree constructing one of potentially many optimal or near-optimal context trees in which leaf nodes represent the context of a near-optimal or optimal context set that may contain contexts of different sizes and geometries. Pruning is carried out using a problem-domain-related weighting function applicable to nodes and subtrees within the context tree. In one described embodiment, a bi-directional context tree suitable for a signal denoising application is constructed using, as the weighting function, an estimated loss function.

Abstract: A system and method for modulating and amplifying an input signal are provided in a communication transmitter. The transmitter includes a pre-distortion lookup table containing pre-distortion lookup data. An auto-calibration module is in communication with the pre-distortion lookup table. The auto-calibration module is configured to operate during a closed-loop auto-calibration interval and to calibrate the pre-distortion lookup data to compensate for a non-linearity in the transmitter. The pre-distortion is based on the pre-distortion lookup data and is used during an open-loop operational interval.

Abstract: Systems and methods for utilizing new communication standards in wireless local area networks are provided that also support legacy wireless stations. The method can include user equipment determining channel state information, selecting a unitary channel decomposition precoder format based on the determined channel state information and transmitting the precoder format information to a base station. During a return transmission the user equipment can receive user data with the precoder format information and utilize a non-linear detector to demodulate and decode the user data. Based on the reception the user equipment can estimate channel quality; and transmitting channel quality information as feedback.

Abstract: A technique for PAR reduction involves producing an optimized clipping pulse. The optimized clipping pulse may be designed to meet certain requirements, such as a spectral mask target or an EVM target, when applied to a signal.

Abstract: System and method of locating an interferer and mitigating its effect for stations of a wireless local area network. Embodiments provide a protocol and mechanism to evaluate the interferer location relative to a wireless link and to take accurate actions to mitigate the interference effect for specific cases. A method includes classifying a location of an interferer relative to a wireless communication device based on a comparison with a clear-channel threshold and a noise-tolerability threshold of the device, categorizing a location of the interferer relative to a wireless link based on a combination of the interference categories for the transmitting and the receiving devices, and mitigating interference in the wireless network according to the categorization. For example, in some cases, mitigating includes adapting a noise-tolerability threshold of the transmitting device to allow transmission.

Abstract: A method for transmitting multicast data in a WiMax/WiBro relay system, including transmitting carrier-interference-noise ratios from UEs to corresponding Relays; selecting the minimum value among the carrier-interference-noise ratios; determining the modulation and coding mode according to the selected minimum value; transmitting the modulation and coding mode to BS; selecting a modulation and coding mode with a highest rate for multicast data on an access link; transmitting the final modulation and coding mode to the Relays; and transmitting data via the access link with the modulation and coding mode determined by the BS.

Abstract: Device, system, and method of flicker noise mitigation. For example, an apparatus includes a digital adaptive filter to mitigate flicker noise from a received Orthogonal Frequency-Division Multiplexing (OFDM) signal, wherein the digital adaptive filter includes: a prediction filter to estimate a value of the flicker noise based on linear combination of past low-pass filtered signal samples; a trainer sub-circuit to modify a coefficient of the prediction filter based on a difference between: a known incoming signal filtered by the prediction filter in a training stage, and a locally-generated reference copy of the known signal; a first path including a first pair of analysis-synthesis filters; and a second, parallel, path including a second pair of analysis-synthesis filters and further including the prediction filter.

Abstract: A communication apparatus used in a spectrum sharing environment in which multiple communication systems coexist using the same spectrum band is provided. The apparatus includes a transmission pulse shaper that performs bandwidth limitation on a pulse which is used to send data symbols; a monitoring unit that monitors in-band interference conditions from coexisting systems other than a target system to which the communication apparatus belongs, and availability of unused spectrum on adjacent channels of the target system; a controller that controls a pulse transmission period and a pulse width of the transmission pulse shaper based on the monitoring result; and a transmission unit that transmits the band-limited signal.

Abstract: A technique for agile region and band conscious frequency planning for wireless transceivers in which a comparison frequency is selected for generating a local oscillator signal. The comparison frequency (Fcomp) is selected for a frequency band of a particular communication standard or protocol, in order not to introduce harmonic components of the selected comparison frequency in a transmitted signal from the wireless device that generates spurious emissions restricted by the particular communication protocol or another protocol. The Fcomp selection may also take into consideration restrictive region-specific criteria for out-of band spurious emissions.

Abstract: A recursive method of calculating an inverse impairments matrix is used to generate an SINR estimate, which in turn is used to generate a CQI estimate. The recursive inverse impairments matrix calculation avoids the need to perform a computationally intensive matrix inversion, allowing for faster CQI estimate generation and consuming less power.

Abstract: Systems and methods are provided for providing a hybrid signal having a reduced crest factor. A digital signal is generated that assumes one of a plurality of vector states at discrete sampling times, with each of the plurality of vector states having an associated phase. An analog signal is monitored to determine when a phase of the analog signal is aligned with the phase of a vector state assumed by the digital signal. A crest factor reduction is applied to the digital signal if the digital signal assumes a vector state having an associated phase aligned with the phase of the analog signal to provide a compressed digital signal. The compressed digital signal and the analog signal are combined to provide the hybrid signal. The analog signal is not altered prior to being combined with the compressed digital signal.

Abstract: The present invention relates, in general, to a joint channel and frequency offset estimation apparatus and method based on a multi-band-orthogonal frequency division multiplexing system, and, more particularly, to a joint channel and frequency offset estimation apparatus and method based on an MB-OFDM system, which uses low-rank LMMSE channel estimation, in which a low-rank is applied to the MB-OFDM system, thus decreasing complexity, and adds a simple structure using the autocorrelation characteristics of an estimated channel, thus joining channel estimation to frequency offset estimation at low complexity. The apparatus includes a channel estimator for receiving a Fourier-transformed OFDM signal, and calculating results of channel estimation using a Linear Minimum Mean Square Error (LMMSE) channel estimation, which minimizes a Mean Square Error (MSE) between an actual channel value and an estimated channel value.

Abstract: A communications receiver may include an adaptive filter unit for removing coherent interference components from a received signal. In the absence of a signal of interest, the filter may adapt dynamically to remove current interference components. When a signal of interest is detected, the filter may be controlled to stop (or at least reduce) its adaptation, to prevent removal of the signal of interest. The received signal may be down-converted to a complex baseband by conditioning circuitry. A detector may detect the signal of interest, and control the filter. Autocorrelation may be used to estimate a characteristic of the signal of interest in the complex baseband. The detector may include hysteresis to react quickly to the start of signal of interest, and more slowly to an end of the signal of interest. The signal of interest may be a frequency shift keyed (FSK) signal. A demodulator may demodulate FSK components based on the autocorrelation result.

Abstract: The present invention provides a simple, easy to implement method and apparatus to reduce jitter in a channel and expand the eye width and eye height of the eye pattern of the signal. The method and apparatus of the present invention reduces jitter specific to a channel in a high speed interface. The present invention utilizes a phasing shifting mechanism based on history of the incoming bits at the receiver. The input bits from the channel are shifted in time before getting to the receiver. This approach significantly reduces Intersymbol Interference (ISI) and deterministic jitter, thus opening up the eye width and eye height for a given interface.

Abstract: A method for calculating zero-crossing reference sequences ({ti}) for the data detection of a sequence of zero crossings ({{circumflex over (t)}i}) of a received signal is disclosed. The data detection is determined in a receiver, wherein the received signal is based on a data symbol sequence ({dk}) angle-modulated at a transmitter and transmitted to the receiver. The zero-crossing reference sequences ({ti}) are calculated in accordance with an equation specifying an output of a finite state machine that describes, at least approximately, the signal generation in the transmitter.

Abstract: Methods and apparatus for allocating tones for communications in the strip-symbol periods in an OFDM system are described. In a strip-symbol, the signal is transmitted using the tones in a tone subset, which is selected from a predetermined set of tone subsets according to a fixed schedule sequence. Adjacent base stations and sectors use the same set of tone subsets but different schedule sequence to minimize the number of collisions between the tone subsets used in adjacent sectors and neighboring cells.

Abstract: A method, circuit and system for determining at least one of an amplitude and a relative phase of a signal under test. A reference signal is generated based, at least in part, upon the at least one of the amplitude and the relative phase of the signal under test. The reference signal is combined with the signal under test to generate a residual signal indicative of a distortion within the signal under test. The residual signal is measured.

Abstract: Method and apparatus are disclosed for obtaining improved performance when using Forward Error Correction (FEC) with channels experiencing block fading or burst jamming over some number of contiguous symbols. One suitable application is when the channel is periodically obstructed due to the rotation of a propeller blade, resulting in a periodic block fading channel. During operation zero symbols are inserted into the received signal stream, prior to the FEC decoder at times that are estimated or otherwise determined to correspond to periods of jamming or severe fading. The zero symbols effectively “erase” the severely degraded symbols. The zero symbols are less detrimental to the FEC decoder than the severely degraded symbols, especially when the channel interleaving/de-interleaving operations result in the zero symbols being temporarily distributed over a large block of received symbols.

Abstract: A digital communications apparatus for processing a data vector includes a transmitter for communicating with a receiver across a channel having channel characteristics. A transmit vector is computed from the data vector and from values defining a basis for a transmit lattice. The transmit lattice defines a set of transmit symbols of length N and is related to an orthogonal receive lattice by the channel characteristics. The computation is performed according to an algorithm of order N complexity.

Abstract: Interference is cancelled from a baseband signal by synthesizing interference from estimated symbols in interfering subchannels. The estimated symbols are hard-coded, soft weighted, or zeroed, depending on the value of an estimated pre-processed signal-to-interference-and-noise ratio (SINR) in each subchannel in order to maximize a post-processed SINR. The estimated pre-processed SINR is obtained from averages of estimated symbol energies and estimated noise variances, or from related statistical procedures.

Abstract: A system having a signal processor for detection of a signal type of a signal is disclosed. One embodiment includes a processor designed to determine a first variable which is characteristic of a first spectrum element of the signal spectrum, and to determine a second variable which is characteristic of a second spectrum element of the signal spectrum. A system is provided for determination of a ratio between the first variable and the second variable, and a detector which is designed to detect the signal type on the basis of the ratio.

Abstract: Apparatus and methods for use in a wireless communication system are disclosed for reducing channel estimation noise in a device such as a wireless transceiver. A disclosed apparatus includes a processor that determines a channel activity portion and a noise portion of a channel estimation. The processor also determines a threshold noise level based on channel estimate values in the noise portion of the channel estimation. The processor compares channel estimate energy values in the channel estimation to the threshold noise level and sets each of the channel estimate energy values being less than the threshold noise level to a predetermined value such as zero in order to reduce or eliminate the noise. Similar methods are also disclosed.

Abstract: Systems and methods are provided to process wireless data packets. A method includes determining a subset of data bits to be processed at a wireless transmitter and employing a clock edge to store the data. The clock edge allows parallel mapping of at least two bits from the subset of data bits into an interleaver memory per a given clock edge. From the memory, other encoding and scrambling processes are applied before transmitting the data packets across a wireless network.

Abstract: A wireless transmitter is configured to map N first samples of a first discrete Fourier transform (DFT) of a group of coded symbols to M sub-carriers according to a first sub-carrier mapping rule. In this case, M is greater than N. The wireless transmitter is also configure to perform a first inverse DFT (IDFT) on the M sub-carriers to provide M second samples and clip the M second samples according to a clipping rule to provide M third samples. The wireless transmitter is further configured to perform a second DFT on the M third samples, de-map the M third samples to N fourth samples, and map the N fourth samples to O subcarriers according to a predetermined second subcarrier mapping rule. In this case, O is greater than or equal to M.

Abstract: A predistortion linearized amplifier system that uses analog polynomial based predistortion is disclosed. An analog polynomial function generator receives polynomial parameter updates from a polynomial parameter generator. The polynomial parameter generator uses a combination of analog and digital signal processing to create the parameter updates. This processing is performed on input signal amplitude, detected using analog circuits, and RF coupled samples of the input signal, and the output signal. By using a combination of analog and digital signal processing means, digital processing can be performed at sub-Nyquist rates, significantly reducing the cost of digital circuits. Also, since the predistortion modulation signal is created with an analog function generator, time correlating delay is minimized reducing circuit costs.

Abstract: A noise filter, used for a digital signal, configuring an [N?1]-stage filter by connecting the N-number of flip flops in series comprises a selection unit for outputting a filter output signal by selecting one of signals filtered by one to (N?1) stages based on a selection signals; and a wave form check unit for making the selection unit change a selection thereby by changing a value of the selection signal based on a pulse width on the filter output signal which is output from the selection unit.

Abstract: The method is based on the capability for coordination of the radio activities of two mobile radio transmitting and/or receiving devices (3, 4). In the case of the method, a value of at least one characteristic variable (PRSSI,BT, N; 15, 16, 17) is first of all determined, which is characteristic of the requirement for coordination of the radio activity of one or both transmitting and/or receiving devices. The coordination of the radio activity of one or both transmitting and/or receiving devices is then activated or deactivated as a function of the value.

Abstract: Methods and systems for processing a single sub-channel that includes two or more combined channels. Using intermediate frequency sub-sampling, two or more channels from a broad band signal are combined into a single sub-channel for further analog and digital processing. Each of the two or more channels is down converted to an intermediate frequency, filtered to remove certain undesired channels, and combined such that the two or more channels are adjacent to each other. A digital representation of the sub-channel is produced from the combined intermediate frequency channels. Each channel within the digital representation is down converted to baseband, and the in-phase and quadrature components are separated from each other. Compared to one direct down conversion technique, intermediate frequency sub-sampling as described in the application may reduce the number of analog to digital converters and control amplifiers used in analog processing by a factor of four.

Abstract: A receiver architecture for receiving an FSK signal having a predetermined number of modulation levels includes a selectivity filter (206) for selectively passing a wanted channel and rejecting unwanted channels. The selectivity filter has a filter bandwidth of about one-half the bandwidth of a pre-modulation filter in a transmitter sending the FSK signal. A discriminator (208) is coupled to the selectivity filter for demodulating the signal. A symbol recovery processor (210) is coupled to the discriminator for recovering the symbols through a maximum likelihood sequence estimation (MLSE) technique utilizing N states for each symbol time, wherein N equals the predetermined number of modulation levels, and wherein templates used in the MLSE for symbol transitions are optimized with a bandwidth substantially less than the bandwidth of the pre-modulation filter.

Abstract: A communications receiver may include an adaptive filter unit for removing coherent interference components from a received signal. In the absence of a signal of interest, the filter may adapt dynamically to remove current interference components. When a signal of interest is detected, the filter may be controlled to stop (or at least reduce) its adaptation, to prevent removal of the signal of interest. The received signal may be down-converted to a complex baseband by conditioning circuitry. A detector may detect the signal of interest, and control the filter. Autocorrelation may be used to estimate a characteristic of the signal of interest in the complex baseband. The detector may include hysteresis to react quickly to the start of signal of interest, and more slowly to an end of the signal of interest. The signal of interest may be a frequency shift keyed (FSK) signal. A demodulator may demodulate FSK components based on the autocorrelation result.

Abstract: The invention relates to a method and system for wideband digital pre-distortion linearization, which is used to overcome the influence of memory effect in radio frequency power amplifier, to expand digital pre-distortion linearization bandwidth, and to improve digital pre-distortion linearization performance.

Abstract: An impulse noise remover includes: a storage module for storing a plurality of digital values derived from a received signal; a calculating module coupled to the storage module for calculating a first detection value according to a first subset of the plurality of digital values, and for calculating a second detection value according to a second subset of the plurality of digital values; a control unit coupled to the calculating module for identifying a target digital value associated with impulse noise according to the first and the second detection values; and a correcting unit coupled to the storage module and the control unit for replacing the target digital value with a predetermined value.

Abstract: A method and apparatus for channel state information generation in a DVB receiver. The present invention comprises: obtaining the magnitude of an error signal and a channel response signal of a sub-carrier; combining the magnitude of the error signal and the magnitude of the channel response signal of each sub-carrier; averaging the magnitudes of the error signals for sub-carriers; calculating the ratio of the channel response signal and the average of the magnitudes of the error signals; and generating a channel state information according to the ratio for the sub-carrier of the OFDM symbol. The method exhibits good performance in either a channel with the AWGN or with co-channel interference, and provides a quick convergence in initialization for the receiver to mitigate the channel impulse response.

Abstract: A method and a power control device moving the resynchronisation point within the guard period to coincide with a calculated reduction in the RF PA power level such that the spurious frequency products are attenuated as much as possible and moved to be as central as possible within the guard period such that neither the previous burst nor the next burst are affected.

Abstract: An apparatus for compensating nonlinearly distorted multicarrier signals, a multicarrier signal receiver using the same, and a method therefor are provided, where the apparatus for compensating multicarrier signals and the multicarrier signal receiver using the apparatus extract parameter information on the HPA mode from the received signal so that nonlinear distortion of the received multicarrier signal is compensated for even though an accurate transfer function of a high power amplifier (HPA) is not known and side information or a special training signal is not transmitted when a signal is transmitted, such that nonlinearly distorted multicarrier signals such as OFDM signals transmitted by an HPA having a variety of transfer functions can be adaptively compensated and therefore a demodulated signal with an improved symbol error rate (SER) can be obtained.

Abstract: A mixer for mixing a digital input signal with a sampled sinusoidal signal, comprising a calculating circuit for calculating multipliers (MC) of a multiplier group (MG) which exhibits a number of dividing circuits for dividing the digital input signal applied to an input of the mixer, and a number of switchable adders/subtractors, the dividing factors of the dividing circuits being Homer coefficients of the resolved multipliers (MC) of the multiplier group (MG), the adders/subtractors being controlled in dependence on a first control bit (SUB/ADD) read out of a memory; a demultiplexer for switching through a zero value or the multiplier (MC) calculated by the calculating circuit in dependence on a second control bit (zero) read out of the memory; and comprising a sign circuit for outputting the positive or negative value switched through by the demultiplexer to an output of the mixer in dependence on a third control bit (SIGN) read out of the memory.

Abstract: Systems, methods, and apparatus for reducing dynamic range requirements of a power amplifier in a wireless device are provided. An exemplary method may include modulating a symbol stream to generate a modulated waveform. The exemplary method may further include generating at least one pulse having a peak aligned with an anticipated position of a peak or a null corresponding to the modulated waveform, where the anticipated position of the a peak or the null corresponding to modulated waveform may be determined by detecting a transition in a phase or an amplitude of the modulated waveform.

Abstract: A method and apparatus for operation in a multi-frequency band system in the presence of an interference, the method comprising the steps of: receiving signaling in a plurality of wideband frequency sub-bands, each wideband frequency sub-band having a different center frequency, wherein a bandwidth of each wideband frequency sub-band is at least 2 percent of a center frequency of the wideband frequency sub-band; detecting an interfering signal having signal energy in a portion of a respective sub-band of the wideband frequency sub-bands; deciding to discontinue use of the respective sub-band; and instructing a transmitting device transmitting the signaling to transmit subsequent signaling in any except the respective sub-band of the plurality of wideband frequency sub-bands.

Abstract: Predistortion effective for a power amplifier with the memory effect is provided. An A/D converter digitizes a signal voltage value after quadrature modulation, and the result is supplied to a subtractor. A lookup table outputs voltage value data in accordance with an output of the subtractor. The output of the lookup table is used as address data for accessing respective lookup tables. The lookup tables output an accumulation adding value derived from multiplying, by impulse responses, the signal voltage value after quadrature modulation and supplies it to the subtractor. The voltage value data outputted from the lookup table is converted by a D/A converter to output it as a predistortion signal for amplitude component for the power amplifier.

Abstract: An I/Q modulator used for processing an I/Q signal to obtain a predistorted output signal. The I/Q signal has an I component and a Q component, and comprises a predistorter for predistorting, with a predistortion signal, a carrier signal, which comprises a first subcomponent and a second subcomponent that is substantially orthogonal to the first subcomponent, to obtain first and second predistorted subcomponents of the carrier signal. The predistortion signal depends on the I and Q components. A first multiplier multiples the I component by the first predistorted subcomponent to obtain a multiplied I component. A second multiplier multiples the Q component by the second predistorted subcomponent to obtain a multiplied Q component. An adder adds the multiplied I component and the negative multiplied Q component to obtain the predistorted output signal. Thus, a simplification of the I/Q modulator and a reduction in the number of necessary multipliers is achieved.

Abstract: Signalling between transmitting means and receiving means wherein signals from the transmitting means are subjected by the receiving means to deliberate reflections and resulting signals are transmitted back as meaningful at the transmitting means, different deliberate reflections having effects on said resulting signals that have different meanings at said transmitting means. Two-way signalling involves first signalling in one direction by sending signals with certainty of deliberate reflection thus resulting signals for return related to the signals sent according to the nature of the deliberate reflection and second signalling in the other direction by varying the nature of the deliberate reflection.