Abstract: Methods and apparatus for processing multichannel signals in a multichannel receiver are described. In one implementation, a plurality of demodulator circuits may provide a plurality of outputs to a processing module, with the processing module then simultaneously estimating noise characteristics based on the plurality of outputs and generating a common noise estimate based on the plurality of outputs. This common noise estimate may then be provided back the demodulators and used to adjust the demodulation of signals in the plurality of demodulators to improve phase noise performance.

Abstract: Joint transmit error (i.e., carrier leak and I/Q mismatch) calibration can be implemented in a transmitter unit in a wireless device. DC signals can be superposed onto digital complex tone signals to generate calibration signals for joint transmit error calibration. The calibration signals may also be phase shifted and/or pre-distorted with digital I/Q phase to yield distinct calibration measurements that can be used for joint transmit error calibration. Digital scaling can be applied at the transmitter unit in accordance with a transmitter gain setting to maintain a constant receiver gain setting. At a receiver unit of the wireless device, the DC signals can be separated from the digital complex tone signals for transmit error calibration. Such a joint transmit error calibration can minimize calibration time, reduce the number of computations required for transmit error calibration, improve the accuracy of the transmit error calibration, and improve performance of the wireless device.

Abstract: A method includes determining one or more metrics indicative of at least one of (i) interference on a communication link, (ii) noise on the communication link, and (iii) performance of a receiver receiving packets via the communication link, selecting a modulation and coding scheme as a function of (i) the determined one or more metrics, and (ii) one or more Quality of Service requirements for the communication link, and correcting the selected modulation and coding scheme using a current value of a correction factor. The corrected modulation and coding scheme is to be used to generate one or more packets. The method also includes determining an error rate corresponding to packets previously transmitted over the communication link, and adjusting the correction factor based on the determined error rate. Adjusting the correction factor includes incrementing or decrementing the correction factor.

Abstract: In a method for generating a physical layer (PHY) data unit for transmission via a communication channel, a first set of modulation coding schemes (MCSs) and a second set of MCSs that correspond to a number of spatial streams and a number of encoders are provided. The first set of MCSs correspond to a first channel bandwidth and the second set of MCSs correspond to a second channel bandwidth, and the first set of MCSs is different than the second set of MCSs. An MCS is selected from the first set of MCSs when the PHY data unit is to be transmitted using a channel having the first channel bandwidth, and the MCS is selected from the second set of MCSs when the PHY data unit is to be transmitted using a channel having the second channel bandwidth. Information bits are encoded using the number of encoders and according to the selected MCS, and the encoded information bits are parsed into the number of spatial streams.

Abstract: Control of a digital communication system having a plurality of communication lines on which signals are transmitted and received is implemented using a variety of methods and systems. According to one embodiment of the present invention, a method is implemented where the signals are affected by interference during transmission and each of the communication lines has at least one transmitter and at least one receiver. A model is created of the interference characteristics due to the signals carried on the communication lines. Interference characteristics for a line are determined based on the model and actual signals carried on other communication lines different from the line for which the characteristics are being determined. Actual interference is compensated for on the communication line using the determined interference characteristics.

Abstract: A system and method for communicating information through a powerline medium including at least three conductors, where the transmitter transmits at least two signals onto the powerline medium and the receiver receives one or more signals from the powerline medium. The transmitter adjusts the power transmitted into the powerline medium in order to set the adjusted transmit power to a predetermined level, e.g., a level that ensures power radiated from the powerline medium does not exceed a regulatory limit. The process of adjusting the transmit power may take into account a functional relationship between the transmitted power and properties of the channel.

Abstract: Method of estimating a channel in a wireless communication system by obtaining a channel impulse response from a pilot signal included in a received signal; estimating a timing offset with a maximum peak power value for the channel impulse response; and performing a phase compensation using the estimated timing offset and estimating a channel which is applied with the compensated phase.

Abstract: This invention uses one or more cancellation modules to eliminate the transmitter leakage at the output of the receive antenna and prior the receiver circuitry so that the received signals can be analyzed without degradation in quality due to simultaneous operation of the transmitter and receiver. Each cancellation circuit could be limited to only 30-50 dB of rejection due to component mismatches and other circuit non-idealities. To obtain further cancellation, more than one cancellation circuit can be applied after the first low noise amplifier. The output of the low noise amplifier can be repeatedly mixed with additional cancellation signals “n” number of times such that the “n” low noise amplifier is mixed with the “nth” cancellation signal. For each additional cancellation signal added a 20-30 dB reduction in noise may be achieved such that cascading three or four cancellation signals from cancellation modules may produce a 150 dB gain.

Abstract: A method for communication includes, in a transmitter having a first number of transmit antenna ports, setting an upper limit on a second number of spatial layers to be used by the transmitter to be less than the first number. An actual number of the spatial layers, which does not exceed the upper limit, is allocated for transmission to a given receiver. One or more streams of modulated symbols are mapped onto the allocated actual number of the spatial layers. The actual number of the spatial layers are transmitted from the transmitter to the given receiver.

Abstract: A method of operation of a communication system includes: calculating a shift distance of a received signal having a distortion; calculating an approximate likelihood of the received signal matching a transmitted signal from the shift distance; determining a bias factor from the distortion; and selecting a determined modulation maximizing a combination of the approximate likelihood and the bias factor for communicating with a device.

Abstract: Provided are an RFID reader and a method for suppressing transmission leakage signals thereof. The RFID reader includes a first loop, a second loop, and a digital signal processor. The first loop suppresses a first transmission leakage signal of an RX signal in response to a first leakage control signal. The second loop suppresses a second transmission leakage signal of the RX signal, received through the first loop, in response to a second leakage control signal. The digital signal processor generates the first leakage control signal and the second leakage control signal. The digital signal processor generates the first leakage control signal until the level of the first transmission leakage signal becomes equal to or lower than the level of a first reference transmission leakage signal.

Abstract: Apparatus and methods for QAM modulation are disclosed using dual polar modulation. QAM modulation of a signal is accomplished by translating a QAM signal into two phasors having the same or constant amplitude and then phase shifting one of the phasor by 180 degrees for a differential load. The phasors are then polar modulated such that, when differentially combined in the load through summation or superposition, a QAM modulated symbol results. The use of constant amplitude phasors when power amplified for transmission of QAM modulated signals allows amplifiers to be operated in a saturation mode with greater efficiency than conventional amplifiers used in QAM modulation, which operate in a less efficient linear mode to effect amplitude modulation. Additionally, differential combining of the phasors affords relaxation of the turns of a transformer used in amplifying the phasors.

Abstract: Provided are a receiver, a transmitter and a radio communication method capable of using non-orthogonal multiple access while suppressing cost increase and processing delay. A mobile station 200A receives non-orthogonal signals, also receives a reference signal to be used for interference cancellation, and extracts the non-orthogonal signal addressed to the mobile station 200A from the received non-orthogonal signals by demodulating and cancelling the radio signal addressed to another mobile station. In addition, the mobile station 200A demodulates the extracted non-orthogonal signal addressed to the mobile station 200A on the basis of the reference signal. The reference signal is multiplexed in the same radio resource block as a resource block allocated to the non-orthogonal signals, and is multiplexed in the radio resource block only when at least one signal is scheduled in the radio resource block.

Abstract: A transmitter and a receiver of a multiple input multiple output (MIMO) communication system may use two codebooks to share channel information. When the transmitter uses eight transmit antennas, two codebooks may be defined. When the receiver generates two precoding matrix indicators from two codebooks, a combination of the two precoding matrix indicators may indicate a single precoding matrix. Precoding matrix candidates may also be defined.

Abstract: Provided are a transmitting apparatus and a transmitting method in a multiple input multiple output system. A power allocation controller includes a block Tomlinson-Harashima precoder (BTHP) that precodes and outputs data to be transmitted to each user in a nonlinear scheme. The BTHP removes and outputs inference signals from data for each user based on the channel information that is fed back from the users. The data for each user output from the BTHP are allocated with power by the power allocation controller. The power allocation controller calculates power allocation parameters so that receiving minimum distances at receiving ends for each user that receive data through the MIMO antennas are the same, and allocates the calculated parameters to data for each user.

Abstract: A method of reducing signal correlation in a symmetrical adaptive canceller link comprising spectrally inverting one of a first carrier signal and a second carrier signal by causing a spectral inversion of one of the first and second carrier signals using a modulator, transmitting the first and second carrier signals within a bandwidth to a remote receiver using a transmitting device such that a composite carrier signal results, and cancelling at least one of the first carrier signal from the composite carrier signal using a cancellation technique such that the second carrier signal results on one end of the link and the second carrier signal from the composite carrier signal using a cancellation technique such that the first carrier signal results on the opposite end of the link.

Abstract: According to an embodiment, a semiconductor integrated circuit includes an amplifier, an interference wave suppression unit, a coupler and a filter control circuit. The interference wave suppression unit includes a filter being controlled to be on or off. The filter is configured to suppress an interference wave component of an amplified signal to output the signal as an output signal when the filter is on. The coupler is configured to detect an input signal or the output signal. The filter control circuit controls the filter to be on when a signal level of a detection input signal or a detection output signal detected by the coupler is greater than or equal to a reference value, and controls the filter to be off when the signal level is smaller than the reference value, at arbitrary determination timing in a period of time between a transmission and a reception.

Abstract: A method and circuit for performing channel equalization in a high speed transmission system comprising a transmitter and receiver. An application specific digital signal processor, ASDSP, performs channel equalization and compensation on digital data received from an analogue-to digital converter of the receiver. The ASDSP is operable to execute an application specific set of op-codes needed for performing channel equalization and compensation. An ASDSP register is coupled between the ASDSP and a system CPU in a feedback loop for performing channel equalization at the receiver. The ASDSP stores equalizer parameters and bit error rate measurements used by the ASDSP for performing channel equalization and compensation. An ASDSP program storage memory, coupled to and accessible by the ASDSP, stores an ASDSP micro-sequence program for controlling the processing steps for channel equalization and dataflow through the ASDSP.

Abstract: Devices, networks, systems and methods for coordinating communications on multi-path radio transmission mesh networks include evaluating available path metrics to ensure the best available connection routes through the network can be understood and utilized. The evaluation of the path metric may include comparing an xth percentile signal strength indication (RSSI) value with a predetermined RSSI threshold level, wherein x is strategically selected to address multi-path signal fading issues.

Abstract: A signal detection apparatus detects the frequency of an input signal without using a PLL. The detection apparatus includes a first and a second orthogonalizer, a phase difference calculator and an integrator, to control the variable coefficient a1 of a band-pass filter. Information e[k]=M·sin(?) representing the phase difference ? between the input data x[k] and the output data y[k] is calculated with the first and second orthogonalizers and the phase difference calculator. The sign of e[k] is inverted and a predetermined integral calculation is performed with the integrator, and the calculated integral value is set as the coefficient a1 of the band-pass filter. Every time input data x[k] is input, the coefficient a1 is changed by reducing it when e[k]>0 and increasing it when e[k]<0. Thus, the frequency of the output signal of the band-pass filter is matched to the input signal.

Abstract: The basic idea of the present invention is to not only design a frequency-selective precoder with respect to the channel properties but also to ensure that the time-domain spread is limited. Hence the energy of the time-domain impulse response of the frequency-selective precoder is concentrated. According to a first embodiment, the time-domain spread is limited by designing a precoder such that it allows smooth transitions in the frequency domain between the values of the precoder when the precoder provides a staircase function. The smooth transitions can either be achieved by lowpass filtering the frequency-domain representation, the staircase function, of the precoder or by designing the precoder such that the sharp jumps are replaced by slopes. According to a second embodiment, the time-domain spread is controlled. The control may be achieved by employing a time-domain parameterization to precisely control the introduced additional time-domain spread.

Abstract: An interference canceller comprises a composite interference vector (CIV) generator configured to produce a CIV by combining soft and/or hard estimates of interference, an interference-cancelling operator configured for generating a soft projection operator, and a soft-projection canceller configured for performing a soft projection of the received baseband signal to output an interference-cancelled signal. Weights used in the soft-projection operator are selected to maximize a post-processing SINR.

Abstract: An arrangement of interleavers allocates bits from an input symbol across sub-symbols transmitted via sub-carriers of multiple orthogonal frequency division multiplex (OFDM) carriers. The input bits are allocated in a fashion to provide separation across subcarriers, and rotation of sub-symbols across the OFDM carriers provides additional robustness in the present of signal path impairments.

Abstract: Channel estimation for wireless communication between a motor vehicle and another communication subscriber is provided, such that, the result from an environment sensor system is used in the channel estimation. Using the environment sensor system, the propagation behavior of the wireless communication in the vicinity of the motor vehicle is recognized and classified, the channel estimation being adapted on the basis of the classification of the propagation behavior.

Abstract: A transmitter (50) includes a nonlinear predistorter (58) having two instances of an inverting transform (106, 106?) that may be implemented in a look-up table (122) and that implements a transform which is the inverse of an average terms component (96) of a nonlinear transform model (94) for an amplifier (70). The look-up table (122) may be updated using a continuous process control loop that avoids Cartesian to polar coordinate conversions. One of the two instances of the inverting transform (106) is cascaded with a non-inversing transform (108) within a residual cancellation section (110) of the predistorter (58). The non-inversing transform (108) implements a transform which is an estimate of a deviation terms component (98) of the nonlinear transform model (94). The residual cancellation section (110) produces a weak signal that replaces an unwanted residual term in an amplified communication signal (76) with a much weaker residual term.

Abstract: Techniques to determine the rate for a data transmission in an OFDM system. The maximum data rate that may be reliably transmitted over a given multipath (non-flat) channel by the OFDM system is determined based on a metric for an equivalent (flat) channel. For the given multipath channel and a particular rate (which may be indicative of a particular data rate, modulation scheme, and coding rate), the metric is initially derived from an equivalent data rate and the particular modulation scheme. A threshold SNR needed to reliably transmit the particular data rate using the particular modulation scheme and coding rate is then determined. The particular rate is deemed as being supported by the multipath channel if the metric is greater than or equal to the threshold SNR. Incremental transmission is used to account for errors in the determined data rate.

Abstract: In a wireless communication system including a transmitter device and a receiver device used for transmission of wireless signals having a plurality of sub-carriers, the transmitter device performs error correction coding on transmitting data and selects at least one of the plurality of sub-carriers used for transmission of error-correction coded data as a null sub-carrier having zero amplitude, thus transmitting the error-correction coded data, while the receiver device receives signals having the plurality of sub-carriers from the transmitter device so as to retrieve original transmitted data by implementing error correction decoding on received signals, thus determining whether an interference wave occurs in the sub-carrier upon detecting reception power exceeding a predetermined threshold in the sub-carrier serving as the null sub-carrier.

Abstract: An objective problem of the invention is to provide a mechanism for improving the performance of a radio access network. According to a first aspect of the present invention, the object is achieved by a method in a first node for adapting a multi-antenna transmission to a second node over an effective channel. The first node and the second node are comprised in a wireless communication system. The method comprises the steps of obtaining at least one symbol stream and determining a precoding matrix having a block diagonal structure. The method comprises the further steps of precoding the at least one symbol stream with the determined precoding matrix, and transmitting the at least one precoded symbol stream over the effective channel to the second node.

Abstract: In one embodiment, a method can provide for dynamic updating of slope values used in determining a soft decision for a demodulated signal obtained in a receiver from a broadcast signal received by the receiver. The method includes generating a channel estimate for a channel traversed by the signal, computing channel state information from the channel estimate, computing statistical information from the channel state information, determining a slope value based at least in part on the statistical information, calculating a log-likelihood ratio (LLR) value for the signal, and applying the slope value to the LLR value to obtain a weighted LLR value.

Abstract: A transmitter transmits to a receiver a training sequence having symbols belonging to a single modulation scheme. At least 90% of symbols have low symbol amplitude, and at most 10% of the symbols have high symbol amplitude. A first symbol estimator estimates the symbols using substantially only the sign of the received symbols, and substantially disregarding symbol amplitudes. A timing recovery mechanism estimates the received symbols in order to continuously reduce a frequency drift between the receiver and the transmitter. The first symbol estimator is switched off and a second symbol estimator is switched on according to a certain criterion. The second symbol estimator estimates symbols belonging to the training sequence. Each of the symbols is estimated to either the low symbol amplitude or the high symbol amplitude. An equalizer uses the symbols estimated by the second symbol estimator to converge, achieve signal equalization, and eliminate inter-symbol interference.

Abstract: In a communication system, a timing-dependence cancelling module is included for cancelling timing-dependence of a transmission signal, so as to render a timing-dependent signal be capable of being utilized on communication systems. Besides, updating an echo cancelling parameter by applying an error difference variable and a data difference variable, or by directly decreasing a step-size coefficient, may also fulfill the purpose of reducing or eliminating timing dependence in a transmission signal of a communication system.

Abstract: A system and method is proposed for progressively quantizing channel state information for application in a MIMO (multiple input multiple output) communication system. A method includes computing an estimate of a communications channel between a subscriber unit and a base station, quantizing the estimate with a first codebook, thereby producing a first quantized estimate, quantizing an (n?1)-th quantized estimate with an n-th codebook, thereby producing an n-th quantized estimate, where n is an integer value ranging from 2 to R, R is a total number of quantizations of the estimate, wherein the n-th codebook is a localized codebook. The method also includes incrementing n, repeating the quantizing an (n?1)-th quantized estimate until n=R, and transmitting information based on the R quantized estimates to the base station.

Abstract: Data coding schemes perform level-based and/or transition-based encoding to avoid signaling conditions that create worst case crosstalk during transmission of multi-bit data from one circuit to another circuit via a parallel communication link. The coding schemes disallow certain patterns from being present in the signal levels, signal transitions, or a combination of the signal levels and signal transitions that occur in a subset of the multi-bit data that corresponds to certain physically neighboring wires of the parallel communication link.

Abstract: A method and apparatus is disclosed to process a received single stream communication signal and/or a multiple stream communication. A communications receiver is configured to receive the received communication signal. A communications receiver determines whether the received communication signal includes a single stream communication signal or a multiple stream communication signal. The communications receiver determines whether a received communication signal complies with a known single stream communications standard. The communications receiver determines whether the received communication signal complies with a known multiple stream communications standard. The communications receiver decodes the received communication signal according to the known single stream communications standard upon determining the received communication includes the signal single stream communication signal.

Abstract: In a wireless communications system, such as a multiband Ultra Wideband communications system, data is transmitted by means of the phases of pulses in multiple frequency bands. A signal is transmitted with a predetermined phase in at least one of the frequency bands for at least a part of the time, and can be used to allow accurate detection of the phases of the signals transmitted in the other frequency bands. One of the frequency bands can be designated as a reference band, and pulses can be transmitted with constant phase in the reference band. More generally, pulses can be transmitted in the other frequency bands with phases which have a known relationship with the phases of the pulses in the reference band.

Abstract: The present invention comprises methods and arrangements for selecting a CQI value based on an estimated or actual transport block size. This is achieved according to an embodiment by mapping the SIR value to a CQI value based on an indication of the expected transport block size to be received by the receiver.

Abstract: Techniques for performing interference cancellation in a wireless (e.g., CDMA) communication system are described. In one aspect, per-bin power estimates for multiple orthogonal bins are derived by estimating at least two components of these power estimates. The components may include, e.g., channel gain, noise and interference, and bin gain. Interference cancellation is performed based on the per-bin power estimates. In another aspect, interference cancellation is performed in multiple stages with fast tracking. A total power estimate and per-bin power estimates are derived for a first stage. A total power estimate is derived for a second stage. Per-bin power estimates are also derived for the second stage based on the total power estimates for the first and second stages and the per-bin power estimates for the first stage. Interference cancellation is performed for each stage based on the per-bin power estimates for that stage.

Abstract: Apparatuses, methods and systems for mitigating carrier offset of a received signal are disclosed. One embodiment of a receiver includes a receiver chain operative to receive a communication signal from a desired transmitter, and a controller operative to determine a carrier offset correction based on prior reception of communication signals from the desired transmitter. The receiver chain is operative to generate a carrier offset corrected received signal by applying the carrier offset correction to the received communication signal, and a correlation processor operative to correlate the carrier offset corrected received communication signal with a known sequence.

Abstract: A method of transmitting control information in a wireless communication system is provided. The method includes configuring downlink control information including a plurality of information fields according to a format of scheduling for transmission of a single codeword in a spatial multiplexing mode, wherein the plurality of information fields include a precoding matrix indicator (PMI) confirmation filed for indicating whether precoding is performed on downlink data by using a PMI reported by a user equipment and a transmitted precoding matrix indicator (TPMI) information field for indicating a codebook index, and at least one of the PMI confirmation field and the TPMI information field indicates an offset value of power for the downlink data transmission or interference information for the downlink data transmission, and transmitting the downlink control information.

Abstract: A data modulation method, a data demodulation method, and a method, include obtaining a target frequency band allocated to a transmitting terminal; calculating a precoding codeword index of spectrum shaping according to a codebook corresponding to a current radio scene and the target frequency band, where the codeword index corresponds to a return-to-zero subcarrier sequence, and the return-to-zero subcarrier sequence serves to calculate a precoding vector for modulating data; and sending the precoding codeword index out through broadcast.

Abstract: Rejecting radio frequency (RF) interference in a communication system. In one aspect, rejecting RF interference includes receiving a signal on a signal path of a receiver from a communication channel, the signal including one or more received signal components having a frequency within a predetermined subset range of frequencies within an operating signal bandwidth of the receiver. The received signal components are attenuated using a notch filter to reduce RF interference obtained during transmission of the signal over the communication channel. In some embodiments, the one or more signal components have been boosted in power at a link partner transmitter connected to the communication channel.

Abstract: A frequency-domain based echo and NEXT canceller is provided. The canceller uses log2 encoding to precondition the error signal representing the echo. An improved gradient constraint is applied on at least a portion of a full weight vector in a least-mean-square algorithm. The least-mean-square algorithm is used to compute filter coefficients. The filter coefficients are multiplied by a frequency-domain data vector using a frequency-domain multiplier to generate frequency-domain output vector.

Abstract: A method and system for pre-distorting a dual band signal to compensate for distortion of a non-linear power amplifier in a radio transmitter are disclosed. In one embodiment, the first signal of the dual band signal is tuned to a first intermediate frequency to produce a first tuned signal and the second signal of the dual band signal is tuned to minus the intermediate frequency to produce a second tuned signal. A single input pre-distorter pre-distorts the sum of the first tuned signal and the second tuned signal. The coefficients of the pre-distorter are obtained from a one-dimensional look-up table.

Abstract: A decoder arrangement comprising a receiver input for parameters of frame-based coded signals and a decoder arranged to provide frames of decoded audio signals based on the parameters. The receiver input and/or the decoder is arranged to establish a time difference between the occasion when parameters of a first frame is available at the receiver input and the occasion when a decoded audio signal of the first frame is available at an output of the decoder, which time difference corresponds to at least one frame. A postfilter is connected to the output of the decoder and to the receiver input. The postfilter is arranged to provide a filtering of the frames of decoded audio signals into an output signal in response to parameters of a respective subsequent frame.

Abstract: A method, an apparatus and a system for transmitting information bits are provided. The method for transmitting information bits includes: dividing the information bits to be transmitted into at least two groups; encoding the information bits to be transmitted in each group; modulating the coded bits obtained by the encoding to obtain modulation symbols, in which each modulation symbol is obtained by the modulation of the coded bits in the same group; and mapping and transmitting the modulation symbols. In this way, the receiving end easily reduces the algorithm complexity, thereby ensuring the performance of the receiving end.

Abstract: An interface module (4) for a unit (1, 2) which is designed to transmit and/or amplify essential communication signals inside an antenna distribution system (29) is specified, said module comprising a first analog interface (6) for forwarding and receiving essential communication signals from mobile terminals (32), a second interface (7) for forwarding and receiving essential communication signals from the antenna distribution system (29), at least one signal path (9, 10) for forwarding the received communication signals between the two interfaces (6, 7), and a controllable digital unit (11) which incorporates the signal path (9, 10) and has means for digitizing incoming communication signals and for subjecting outgoing communication signals to analog conversion. In this case, the digital unit (11) is designed to identify essential communication signals in the digitized communication signals, to mask the remaining signals and to forward the essential communication signals.

Abstract: A method and system for a sequence estimation in a receiver, such as for use when receiving a sample of a received inter-symbol correlated (ISC) signal corresponding to a transmitted vector of L symbols, with L being a integer greater than 1, and with symbol L being a most-recent symbol and symbol 1 being least recent symbol of the vector. A plurality of candidate vectors may be generated, wherein element L-m of each candidate vector holding one of a plurality of possible values of the symbol L-m, with m is an integer greater than or equal to 1, and elements L-m+1 through L of each candidate vectors holding determined filler values. A plurality of metrics may be generated based on the plurality of candidate vectors, and based on the generated plurality of metrics, a best one of the possible values of the symbol L-m may be selected.

Abstract: An impedance correction device and a method thereof are provided. A step generator is used to generate a step signal and send to a circuit under test. A reflected signal returned back from the circuit under test is used as a measurement signal; and the measurement signal can be measured to obtain a characteristic impedance value. When the measurement signal is greater than the initially measured step signal, an impedance value of a correction resistor is increased; when the measurement signal is smaller than the initially measured step signal, the impedance value of the correction resistor is reduced. Through adjustment of the correction impedance value, impedance matching between the correction impedance value and the characteristic impedance value is achieved.

Abstract: A method includes transmitting a first set of transmission signals over an operating frequency band. The method includes detecting if a second set of transmission signals are transmitted adjacent the operating frequency band and reducing power to a subset of the first set of transmission signals when the second set of transmission signals are detected.

Abstract: The present invention relates to a transmission interference cancellation method for a multiuser MIMO system. The method includes decomposing a channel matrix to represent formulae of permutation matrixes including a first matrix and a second matrix; determining an optimal permutation matrix among a plurality of available permutation matrixes using a norm of multiplication of the second matrix and a transmitting data vector; and determining the second matrix using the determined optimal permutation matrix and calculating a transmitting precoding vector using the determined second matrix and the transmitting data vector.