Abstract: A method includes determining a first aggregate received power level of an orthogonal frequency division multiplexed (OFDM) signal received at a first network node, adjusting a nominal PHY Margin an amount that is dependent upon a measurement of an aggregate received power level of the OFDM signal, determining a data transmission rate based on the adjusted nominal PHY Margin, and receiving data being transmitted in accordance with the data transmission rate at the first node.

Abstract: A transmission unit includes a transmission pulse signal generating circuit which generates a transmission pulse signal having pulses corresponding to a plurality of clock signals generated in a clock signal generating circuit, existing between a first pulse and a second pulse which are generated in an edge pulse generating circuit. A receiving unit is configured to decode a received pulse signal based on the transmission pulse signal received from the transmission unit via an isolated communication unit, as a signal that transitions from a first level to a second level when an initial pulse of the received pulse signal is detected and that transitions from the second level to the first level when a subsequent pulse is not detected within a predetermined first time period from when a most recent pulse of the received pulse signal is detected.

Abstract: In a transmission method using spectrum shaping, interference to other cells caused by an increase in transmit power of mobile station apparatuses is suppressed. A wireless control apparatus performs control in which at least one wireless terminal apparatus clips part of frequencies in a system band and locates a transmit signal. The wireless control apparatus determines frequencies at which the individual wireless terminal apparatuses locate transmit signals, so that an interference level of the entire system band is suppressed to be lower than or equal to a certain value. Also, the wireless control apparatus determines frequencies at which the individual wireless terminal apparatuses locate transmit signals, so that a total sum of frequency bands allocated to the wireless terminal apparatuses before clipping is smaller than or equal to the system band.

Abstract: Embodiments of the invention are generally directed to simultaneous transmission of clock and bidirectional data over a communication channel. An embodiment of a transmitting device includes a modulator to generate a modulated signal including a clock signal and a data signal, the clock signal being modulated by a first signal edge of the modulated signal and the data signal being modulated by a position of a second signal edge of the modulated signal; a driver to drive the modulated signal on a communication channel; an echo canceller to subtract reflected signals on the communication channel; and a data recovery module to recover a signal received on the communication channel, the received signal being encoded by Return-to-Zero (RZ) encoding, the signal being received simultaneously with driving the modulated signal on the communication channel.

Abstract: A method of canceling impulsive interference from a communications signal is provided. The method includes identifying an impulse interference contained in the communications signal, generating a model of impulse interference, matching the model in at least one of amplitude, phase and envelope time delay to the identified impulse interference, and cancelling the identified impulse interference by subtracting the matched model from the identified impulse interference.

Abstract: The method includes receiving a signal comprising a symbol-carrier matrix, the symbol-carrier matrix including a predetermined pattern of pilot symbols, and determining first channel estimates at pilot symbol positions of the pilot symbols in the symbol-carrier matrix. The method further includes correcting the first channel estimates at the pilot symbol positions using Bayesian estimation, and determining second channel estimates at symbol positions other than the pilot symbol positions using interpolation based on the correct first channel estimates.

Abstract: An apparatus and a method for operating a Mobile Station (MS) in a wireless communication system are provided. The method includes receiving a threshold for a gap of an average Receive (Rx) power between a neighboring Base Station (BS) and a serving BS, transmitting to the serving BS, identification information of a BS having the average power greater than a first value, receiving information of a BS involving joint processing generated using information of the BS having the average power greater than the first value, feeding Precoding Matrix Index (PMI) information of the BS involving the joint processing, back to the serving BS, receiving information indicating a PMI operation mode of the MS, from the serving BS, and determining a PMI operation mode according to the information indicating the PMI operation mode of the MS.

Abstract: A method is provided for processing received data symbols in an orthogonal frequency division multiplexing (OFDM) transmission scheme, and an OFDM baseband receiver which performs this method, in order to support frequency selective noise estimation, especially in interference limited environments, and to offer improved estimation performance and reduced computational complexity.

Abstract: A resource allocation in a broadband wireless communication system is provided. An apparatus for a base station in a broadband wireless communication system includes a manager for managing resources by dividing the resources into a plurality of regions based on a maximum supportable error vector magnitude (EVM) in a frequency axis; and an allocator for allocating resources of a region other than a first region, the region having the smallest maximum supportable EVM, to a service to which a maximum modulation and coding scheme (MCS) level is not applied.

Abstract: The present technology provides noise reduction of an acoustic signal using a configurable classification threshold which provides a sophisticated level of control to balance the tradeoff between positional robustness and noise reduction robustness. The configurable classification threshold corresponds to a configurable spatial region, such that signals arising from sources within the configurable spatial region are preserved, and signals arising from sources outside it are rejected. In embodiments, the configurable classification threshold can be automatically and dynamically adjusted in real-time based on evaluated environmental conditions surrounding an audio device implementing the noise reduction techniques described herein.

Abstract: Interference is estimated in an Orthogonal Frequency Division Multiplexing system by receiving at a wireless receiver pilot symbols and data symbols transmitted in time and frequency via resource blocks, detecting a first one of the data symbols transmitted to the wireless receiver via a time-frequency resource element of a first one of the resource blocks and identifying a second one of the resource blocks adjacent the first resource block having related interference parameters. The interference is estimated based on the pilot symbols transmitted via the first resource block and the pilot symbols transmitted via the second resource block.

Abstract: Example embodiments include methods of interference cancellation at NodeB receivers of baseband antenna signals including physical channels. The methods include canceling interference from a received baseband antenna signal by removing a reconstructed baseband signal from the processed received baseband antenna signal. The processed reconstructed baseband signal includes users whose physical data channel signals were successfully decoded. Methods also include removing interference from a received baseband signal to form an interference cancelled baseband signal that will be processed by the receiver. The interference cancelled baseband signal is the received baseband antenna signal minus users' signal interference contributions whose demodulated physical data channel signals have a determined user symbol energy value that exceeds a threshold. Methods further include removing interference from a user's signal to be error corrected.

Abstract: A system for compensating for a Doppler frequency shift in communications between a mobile node and a fixed node. The system includes a Doppler frequency shift estimation unit configured to estimate the Doppler frequency shift experienced in a communication signal between the mobile node and the fixed node, wherein the Doppler frequency shift is estimated based on a location of the mobile node, a heading of the mobile node, and speed of the mobile node, and a location of the fixed node. The system also includes a frequency shift unit configured to shift a frequency of the communication signal in accordance with the estimated Doppler frequency shift.

Abstract: There is described the use of Digital Radio Frequency Memory (DRFM) modules to jam certain communication signals while allowing others to be received on a given frequency band. The DRFM modules exploit the multi-path phenomenon by using transmitted signals to cause full band destructive echoes and/or distortions. A set of receivers used in conjunction with the DRFM modules are aware of the exact multi-path induced by the DRFM modules and are therefore able to mitigate or even benefit from the effects of the destructive multi-path and maintain or improve communications.

Abstract: For processing symbols transmitted in frames and separated by guard intervals via a propagation channel between first and second communicating entities using time-division duplexing, the second entity receives at least one pulse transmitted by the first entity. The second entity estimates the impulse response of the propagation channel as a function of the pulse received and time reverses the estimated impulse response in order to filter the symbols as a function of the time-reversed impulse response. The second entity then transmits the modulated symbols and a second pulse to the first entity during a guard interval in a frame in order to process the modulated symbols.

Abstract: Embodiments provide a MIMO system having a plurality of service antennas and method for data transmission and reception. The system includes a plurality of service antennas, where each service antenna is configured to simultaneously serve a plurality of terminals and independently receive a pilot sequence from the plurality of terminals. The system further includes a plurality of channel estimation units configured to independently generate an antenna-specific channel estimate based on the received pilot sequence and a plurality of pre-coding units configured to independently generate a coded signal to be transmitted to the plurality of terminals via a respective service antenna based on a set of data symbols and the antenna-specific channel estimate.

Abstract: One embodiment includes a method of receiving a transmitted signal. The method comprises receiving a signal transmitted over a channel. The signal comprises a known signal and an information signal. The method further includes determining at least one indicator of channel characteristics based at least in part on the portion of the known signal. The method further includes generating a first value indicative of the information signal based at least in part on the at least one indicator of the channel characteristics. The first value comprises an error signal. The method further comprises removing the error signal from the first estimate of the signal based at least in part on the portion of the known signal. Other embodiments include systems for performing the method and methods of making such systems.

Abstract: The DFT 12 converts a modulated digital signal into a spectrum of a frequency band. A use frequency band notification unit in a reception device notifies a transmission device 1 of a use frequency band. A deletion unit 141 in the transmission device 1 deletes a spectrum of a band other than the use frequency band after shaping of a spectrum waveform based on the water filling principal by a shaping unit 13. Then, a digital signal for each data series concerning the spectrum obtained after deletion by the deletion unit 141 is synthesized by a synthesizing unit 16 and sent from the transmission device 1 to the reception device. A reception side conversion unit in the reception device converts the digital signal sent by the transmission unit into a spectrum of a frequency band. A turbo equalization unit performs turbo equalization on the converted spectrum.

Abstract: A post-distorter compensates for receiver nonlinearity in calibration mode. Linearized receiver-side output from the post-distorter is used to correctly compensate for transmitter-side nonlinearities in calibration mode. The post-distorter also compensates for receiver-side nonlinearities during normal receive mode. Thus, the post-distorter features dual modes of use, a calibration mode, wherein calibration signals received from the adjacent transmitter are linearized by the post-distorter and a normal receive mode, wherein communication signals from a remote transmitter are linearized by the post-distorter.

Abstract: A time delay adjustment method is provided, which includes the following steps. A same scrambling signal is added into two received signals. The added scrambling signals are then extracted. A delay difference between the two signals is detected according to a difference between the two extracted scrambling signals. The delay difference between the two signals is adjusted by delaying one or both of the two signals. Furthermore, a time delay adjustment device and an optical transmission apparatus are also provided. Therefore, time delay can be adjusted online, and real-time monitoring and adjustment of delay difference is also achieved.

Abstract: Methods and apparatuses for minimizing co-channel interference in communications systems are disclosed. A method in accordance with the present invention comprises shifting a characteristic of the first signal with respect to a like characteristic of the second signal to mitigate co-channel interference, and transmitting the first signal and the second signal over different channels of the communication system.

Abstract: Apparatus may be provided including a spectrum analyzer and decision circuitry. The spectrum analyzer may be configured to ascertain wireless signal signature data from a wide range of frequency bands. The decision circuitry may be configured to modify operation of one or both of a receiver and a transmitter based on the signal signature data.

Abstract: A communication system capable of achieving a high usage efficiency of frequencies without the need for cooperation of multiplexed users is disclosed. The communication system communicates over frequency channels set by dividing a frequency bandwidth assigned to the system and allows interference between channels by overlapping the adjacent frequency channels with each other in the frequency domain. A transmitting and receiving device, which transmits and receives a signal by allowing the interference between symbols at a waveform level for each channel to decrease the occupied bandwidth, is provided. The receiving device is provided with an Inter-Channel Interference (ICI) removal and Inter-Symbol Interference (ISI) compensation filter serving as either an ICI removal filter for removing the interference between channels or an ISI compensation filter for compensating the interference between symbols.

Abstract: An electronic device includes an analog-to-digital converter adapted to receive a radio-frequency signal and adapted to provide therefrom a digital signal, wherein the radio-frequency signal may include an interference signal. The electronic device has a controller adapted to perform a digital measure on the digital signal and adapted to generate therefrom a selection signal having a first value indicating a non-interference condition in the radio-frequency signal and having a second value indicating an interference-condition in the radio-frequency signal. A selector is adapted to transmit the digital signal in case the selection signal has the first value and to transmit a signal replacing the digital signal in case the selection signal has the second value.

Abstract: Embodiments provide an apparatus and method for interference alignment for channel-adaptive waveform modulation. The method includes obtaining at least a part of a first matrix and a part of a second matrix for the impulse response function of a communication channel. The method further includes designing a set of one or more linearly independent waveforms based on at least the obtained parts of the first and second matrices such that a first subspace spanned by the linearly independent waveforms when multiplied by the obtained part of the first matrix at least partially overlaps a second subspace spanned by the linearly independent waveforms when multiplied by the obtained part of the second matrix.

Abstract: A signal receiver apparatus includes a waveform shaping data storage device storing waveform shaping data of a signal transmitted with a given timing from a signal transmitter device of a plurality of signal transmitter devices which are coupled to the signal receiver apparatus for each of the plurality of signal transmitter devices, and a waveform shaping device reading waveform shaping data of the signal transmitter device in the plurality of signal transmitter device from the waveform shaping data storage device when a signal from the signal transmitter device is received, and shaping a waveform of a received signal from the signal transmitter device.

Abstract: Methods of controlling a transmission power and configuring a codebook in a multi-antenna system to solve a transmission power unbalance between antennas are disclosed. The method of transmitting data in a multi-antenna system includes (A) transmitting one or more pilot signals within a first symbol region through a first antenna unit, and (B) transmitting one or more pilot signals within a second symbol region through a second antenna unit, wherein data within the first symbol region is transmitted through the second antenna unit, and data within the second symbol region is transmitted through the first antenna unit. According to the present invention, since a transmission power unbalance between antennas is solved, a transmission power can be uniformly assigned to each antenna and channel estimation can be easily performed. Moreover, a power amplifier having a uniform amplification range can be used and designed.

Abstract: To enable transmission power control (outer loop control) considering changes (for example, changes in encoding gain and number of diffusions or the like) in durability for transmission error. The radio communication apparatus for controlling a target quality of a received signal used for the inner loop power control with outer loop power control. The radio communication apparatus comprises a detector operable to detect a change in durability for transmission error of received data and an update controller operable to execute a gradual update of the target quality for detection of high durability, when the detected durability is low.

Abstract: Method, receiver and computer program product for processing a signal transmitted from a plurality of spatially separated transmit antennas using a Multiple-Input Multiple-Output transmission over a wireless network. The signal is received at a plurality of spatially separated receive antennas, the signal comprising a plurality of data streams and the quality/reliability of each of the data streams in the received signal is determined. Based on the determined quality/reliability of the data streams, a decoding technique is selected to be one of (i) a successive decoding technique for successively decoding data streams in which one of the data streams is decoded and a signal corresponding to said one of the data streams is removed from the received signal prior to decoding further data streams in the received signal, and (ii) a non-successive decoding technique in which each data stream is decoded from the received signal by treating the other data streams as noise in the received signal.

Abstract: The present disclosure provides a receiving device including, a receiver configured to receive a signal that is transmitted via a propagation path and is modulated by a predetermined system prescribed by a predetermined standard, a demodulator configured to demodulate a received signal, an estimator configured to estimate a signal-to-noise ratio relating to the propagation path, obtained from a data signal included in the demodulated received signal, and a corrector configured to correct an estimated signal-to-noise ratio in accordance with a transmission parameter obtained from the received signal.

Abstract: A method of operation of a communication system includes: calculating a total received power estimation based on a designated received signal having a designated pilot symbol; calculating an instantaneous channel estimation based on the designated pilot symbol calculating a channel gain power estimation based on the instantaneous channel estimation; calculating a total interference power estimation based on a difference between the instantaneous channel estimation and a delayed channel estimation; calculating a designated received power based on a difference between the total received power estimation and the total interference power estimation; and determining a relative transmission power estimation based on the designated received power and the channel gain power estimation for communicating with a device.

Abstract: The present disclosure shows new mechanisms fir sampling an input signal. In particular, some embodiments of the present disclosure include a new type of a level-crossing sampling mechanism called a derivative level-crossing sampling (D-LCS). At a high level, D-LCS involves quantizing the derivative of an input signal when the derivative of the input signal crosses one of the quantization thresholds. For certain class of signals, the derivative of the input signal can vary at a slower speed compared to the amplitude of the input signal. Therefore, by sampling the derivative of the input signal, instead of the input signal itself, the number of samples per unit time can be reduced.

Abstract: A system and machine-implemented method are described for performing precoding interpolation in a DIDO system which employs orthogonal frequency-division multiplexing (OFDM) and DIDO precoding to communicate with a plurality of distributed-input-distributed-output (DIDO) clients. For example, a system according to one embodiment of the invention comprises: selecting a first subset of ODFM tones to determine a first subset of precoding weights; deriving a second subset of precoding weights for a second subset of ODFM tones by interpolating between the first subset of precoding weights; and using a combination of the first subset of precoding weights and the second subset of precoding weights to precode a data stream prior to transmitting the data stream to a DIDO client.

Abstract: Modulated orthogonal frequency division multiplexing (OFDM) subcarriers generate high sidelobes, resulting in adjacent channel interference (ACI). Current sidelobe suppression techniques, such as inserting guard intervals or cancellation carrier bands, diminish the useful radio spectrum or consume significant wireless device resources. Disclosed is a method of suppressing sidelobes through adding an adaptive extension to OFDM symbols that is calculated to avoid ACI while keeping power consumption to low levels. Bandwidth and user location information are collected by a cognitive radio an utilized to determine the extension used. The method significantly reduces ACI to other bands and reduces the required guard bands, opening the radio spectrum to more efficient use.

Abstract: A baseband processing module according to the present invention includes a multi-path scanner module. The multi-path scanner module is operable to receive timing and scrambling code information regarding an expected multi-path signal component of a WCDMA signal. Then, the multi-path scanner module is operable to identify a plurality of multi-path signal components of the WCDMA signal by descrambling, despreading and correlating a known symbol pattern of/with a baseband RX signal within a search window. The multi-path scanner module is operable to determine timing information for the plurality of multi-path signal components of the WCDMA signal found within the search window and to pass this information to a coupled rake receiver combiner module.

Abstract: A method and system for dynamic configuring of one or both of a transmitter pulse-shaping filter and a receiver pulse-shaping filter to generate a total partial response that incorporates a predetermined amount of inter-symbol interference (ISI). The predetermined amount of ISI is determined based on an estimation process during extraction of data from an output of the receiver pulse-shaping filter, such that performance of total partial-response-based communication matches or surpasses performance of communication incorporating filtering based on no or near-zero ISI. The reconfiguring may comprise obtaining data relating to changes affecting one or more of: the pulse-shaping filtering, and a channel and/or an interface used in the communication of data based on the total partial response, and adjusting the filter configuration, such as by determining a new optimized filtering configuration or changes to existing configurations (e.g., by applying a filtering optimization process).

Abstract: A method and system to reduce the power supply noise of a platform during the training of high speed communication links. In one embodiment of the invention, the device has logic to stagger a bit lock pattern for each of one or more communication links and scramble a training sequence for each of the one or more communication links. By doing so, it removes the need for anti-noise circuits and in turn, reduces the silicon area and power of the devices. Further, by having the logic in the physical layers to facilitate the training of the communication links, it eliminates the need to redesign the package of the devices to shift the resonant frequencies.

Abstract: A method includes determining a signal strength value for a first received signal received from a first station in a first network. The first received signal is received in the first network through a shared communication medium that is shared with a second network. The method includes receiving an indicator of a signal strength value determined for a second received signal from a second station in the second network. Based on the signal strength value for the first received signal and based on the indicator of the signal strength value determined for the second received signal, a detection threshold is selected such that, in response to a third received signal having a signal strength in excess of the detection threshold, the third received signal is processed according to a protocol of the first network and is not processed according to a protocol of the second network.

Abstract: A communication level table storage unit stores a communication level table that defines correspondence between a communication level at least defined by MCS (modulation scheme and coding rate) and a range of required CINR at the communication level. A communication quality management unit obtains CINR of a received signal at another communication apparatus which is a communication partner. A setting unit refers to the communication level table, and when a difference between a representative value of a range of required CINR at a current communication level and a representative value of a range of required CINR of CINR at a communication level which is one level higher is more than or equal to a threshold value, sets a communication level such that the obtained CINR of the received signal is included in the range of required CINR.

Abstract: Disclosed are data transmission/reception apparatus and method that may be applied to a case where additional data is to be transmitted in a CE-OFDM modulation/demodulation scheme that satisfies an OFDM feature which is robust against multipath fading and simultaneously has a feature that amplitude is constant. Service channel information, modulation parameter information of a physical layer, and the like, may be transmitted by using an additionally secured information channel. If using this, a service search time may be saved, and power of a receiver may be reduced.

Abstract: An access node is configured to control crosstalk between an activating channel associated with a first terminal and active channels associated with respective other terminals. The access node detects a control signal sent by the first terminal over the activating channel in a designated phase of an initialization process of the first terminal, determines an error signal from the detected control signal, correlates the error signal with one or more corresponding signals sent by respective ones of the other terminals over the active channels, estimates crosstalk from the active channels into the activating channel based on the correlation, and configures a vectoring signal processing module to control the estimated crosstalk. The control signal sent by the first terminal comprises a value selected by the first terminal from a set of two or more values and prior to its detection the particular selected value is unknown to the access node.

Abstract: A method and apparatus to drive a load using a pulse-width modulated (PWM) signal and spread a spectrum of the PWM signal across a plurality of frequencies while maintaining a constant duty cycle for the load.

Abstract: A method (300) for performing dual carrier modulation (DCM) precoding. The method comprises generating data sub-blocks (S320), independently interleaving the sub-blocks (S330), generating bit vectors by grouping bits of the interleaved sub-blocks (S350), mapping the bit vectors into data symbols (S360), and precoding the data symbols using a precoding matrix to generate precoded symbols (S370).

Abstract: An apparatus including an adder, a delay line, and a first detector. The adder may be configured to generate an input signal in response to a received signal and a feedback signal. The feedback signal may include a contribution from each of a plurality of delayed versions of the input signal. The contribution from each of the plurality of delayed versions of the input signal may be determined by a respective weight value. The delay line may be configured to generate the plurality of delayed versions of the input signal. The first detector may be configured to recover a data sample from the input signal in response to a clock signal.

Abstract: The radio communication device offers data communication with no adverse effect of EMI radiation. In response to EMI radiation detected by the radiation detector, the controller changes the normal communication mode into the avoidance communication mode. In the avoidance communication mode, the transmitter prepares a transmission packet so as to satisfy the following relational expressions: T1=T0/2/M and T2=T0/2 (where, T0 represents the cycle of an AC power source; T1 represents the transmission time; and T2 represents the transmission cycle). The transmission power changer determines the transmission power by multiplying T2/T1 to the transmission power in the normal communication mode. The transmission rate changer determines the transmission rate by multiplying T2/T1 to the transmission rate in the normal communication mode. The transmission packet is transmitted in synchronization with the stopping time of EMI radiation detected by the timing detector.

Abstract: Systems and methods are disclosed for removing interference in a time-harmonic received composite signal, comprising, sampling an in-band interfering signal from a stationary transmitter at a stationary receiver; sampling a composite signal having the in-band interfering signal and an in-band desired signal from a stationary transmitter at the receiver, deriving at least one of a phase and time difference from the composite signal and sampled in-band interfering signal, applying the derived at least one of phase and time difference to the sampled in-band interfering signal to estimate a synchronized current in-band interfering signal, and generating the un-interfered, in-band desired signal by subtracting the synchronized current in-band interfering signal from a current composite signal.

Abstract: This disclosure relates a method and apparatus for generating pre-coding matrix codebook. The method for generating pre-coding matrix codebook, comprising: acquiring a universal set of pre-coding matrixes in a first format; acquiring a universal set of pre-coding matrixes in a second format; selecting a first predetermined number of pre-coding matrixes in the first format from the universal set of pre-coding matrixes in the first format; and selecting a second predetermined number of pre-coding matrixes in the second format from the universal set of pre-coding matrixes in the second format, according to the selected first predetermined number of pre-coding matrixes in the first format.

Abstract: A method (400) for performing a multiple-sub-carrier-joint-modulation (MSJM) precoding. The method includes grouping input information bits into bit blocks (S410); converting the bit blocks into bit vectors (S420); mapping each of the bit vectors into a symbol vector (S430); and modulating symbol vectors into data subcarriers (S440).

Abstract: A receiver may be operable to generate estimates of transmitted symbols using a sequence estimation process that may incorporate a non-linear model. The non-linear model may be adapted by the receiver based on particular communication information that may be indicative of non-linearity experienced by the transmitted symbols. The receiver may generate a reconstructed signal from the estimates of the transmitted symbols. The receiver may adapt the non-linear model based on values of an error signal generated from the reconstructed signal, and the values of the error signal may be generated from a portion of the generated estimates that may correspond to known symbols and/or information symbols. The values of the error signal corresponding to the known symbols may be given more weight in an adaptation algorithm, and the values of the error signal corresponding to the information symbols may be given less weight in the adaptation algorithm.

Abstract: For voltage values (observed noise sequence) in an electronic power line (communication medium) which are obtained at a predetermined interval, initial values of noise characteristics based on a statistic of the observed noise sequence itself are decided by a moment method (S301 to S307), the noise characteristics (state transition probabilities and state noise power) for maximization of the likelihood of the observed noise sequence are obtained from the initial values by MAP (Maximum A Posteriori) estimation using a Baum-Welch algorithm (S309 to S312), a state sequence is estimated from the obtained noise characteristics, and an impulsive noise at each time point is detected.