Patent application number | Description | Published |
20110002689 | OPTICAL OFDM RECEIVER, OPTICAL TRANSMISSION SYSTEM, SUBCARRIER SEPARATION CIRCUIT, AND SUBCARRIER SEPARATION METHOD - A high-performance optical OFDM receiver is realized. A subcarrier separation circuit receives an optical OFDM signal consisting of two subcarriers A and B and separates a subcarrier component, signal light and first local oscillator light are input to the subcarrier separation circuit, the subcarrier separation circuit converts the signal light and the first local oscillator into a baseband electrical signal, the subcarrier separation circuit converts the baseband electrical signal into a digital signal, the subcarrier separation circuit shifts the frequency of the converted digital signal so that a center frequency of the subcarrier A becomes zero, and the subcarrier separation circuit adds a frequency shifted signal to a signal obtained by delaying the frequency shifted signal by ½ of a symbol time to separate a component of the subcarrier A. | 01-06-2011 |
20110129041 | RECEIVER DEVICE, COMMUNICATION SYSTEM AND RECEIVING METHOD - A receiver device receives a signal inputted to one or a plurality of ports as a plurality of received signals, and includes: a phase offset estimating unit that, on the basis of a unique word of each signal block contained in said received signal, estimates the phase offset, and a phase offset compensating unit that, on the basis of a phase offset estimated by said phase offset estimating unit, compensates the phase offset; the receiver device uses a known signal component (unique word) contained in a frequency-domain equalized signal to compensate the phase offset, whereby it compensates complex phase offset fluctuation, and estimates the phase offset of a signal obtained at each port. | 06-02-2011 |
20120070159 | SIGNAL GENERATING CIRCUIT, OPTICAL SIGNAL TRANSMITTING APPARATUS, SIGNAL RECEIVING CIRCUIT, METHOD FOR ESTABLISHING OPTICAL SIGNAL SYNCHRONIZATION, AND OPTICAL SIGNAL SYNCHRONIZATION SYSTEM - To enable signal position detection, frequency offset compensation, clock offset compensation, and chromatic dispersion amount estimation in a communication system based on coherent detection using an optical signal, even on a signal having a great offset in an arrival time depending on a frequency due to chromatic dispersion. An optical signal transmitting apparatus generates specific frequency band signals having power concentrated on two or more specific frequencies and transmits a signal including the specific frequency band signals. An optical signal receiving apparatus converts a received signal into a digital signal, detects positions of the specific frequency band signals from the converted digital signal, estimates frequency positions of the detected specific frequency band signals, and detects a frequency offset between an optical signal receiving apparatus and an optical signal transmitting apparatus. Moreover, the optical signal receiving apparatus detects a clock offset between the optical signal receiving apparatus and the optical signal transmitting apparatus from an interval between the estimated frequency positions of the specific frequency band signals. Furthermore, the optical signal receiving apparatus estimates temporal positions of the detected specific frequency band signals and detects a chromatic dispersion amount from a difference between the temporal positions of the specific frequency band signals corresponding to different frequencies. | 03-22-2012 |
20120099460 | RADIO COMMUNICATION METHOD, RADIO COMMUNICATION SYSTEM, RADIO BASE STATION, AND RADIO TERMINAL STATION - This radio communication method is used to perform spatial multiplexing communication between cells in the overlap cell environment. In the MU-MIMO overlap cell environment, when a null is formed between a radio base station and a radio terminal station belonging to different cells, a first set of a “call signal” and a “response signal” is used to perform mutual detection with the radio base station and the radio terminal station belonging to different cells, and then a null is formed so as not to cause interference of radio waves between the radio base station and the radio terminal station belonging to different cells. At this time, the addresses of the radio base station and the radio terminal station are used to discriminate whether the radio base station and the radio terminal station belong to the same cell or different cells. | 04-26-2012 |
20120099864 | CHROMATIC DISPERSION VALUE CALCULATING APPARATUS, OPTICAL SIGNAL RECEIVING APPARATUS, OPTICAL SIGNAL TRANSMITTING APPARATUS, AND CHROMATIC DISPERSION VALUE CALCULATION METHOD - In order to compensate for chromatic dispersion caused by optical fiber transmission in a communication system with coherent detection using optical signals, specific frequency band signals are used to enable estimation of a chromatic dispersion value. The chromatic dispersion value calculating apparatus is provided with: a signal distributing circuit which distributes, into a plurality of signal sequences, an electrical digital signal converted from received optical signals of an optical signal transmitted by an optical signal transmitting apparatus, in which a known signal with concentrated frequency components of a plurality of specific frequencies is appended to a signal generated from a transmission data sequence; a plurality of frequency band pass filter circuits, each of which separating only each of a plurality of specific frequency components in which the known signal is included from each of the signal sequences distributed by the signal distributing circuit, and passing each of the specific frequency components therethrough; a plurality of power calculating circuits which are provided so as to correspond respectively to the plurality of frequency band pass filter circuits and which calculate power values of signals output from the corresponding frequency band pass filter circuits; a delay time calculating circuit which detects times at which power has the maximum value or times at which the power exceeds a predetermined threshold value, respectively from signal sequences of the power values output from the plurality of power calculating circuits, and which compares the detected times; and a chromatic dispersion value calculating circuit which calculates a chromatic dispersion value based on a comparison result of the times by the delay time calculating circuit. | 04-26-2012 |
20120106618 | METHOD FOR RECEIVING FREQUENCY DOMAIN MULTIPLEXED SIGNAL AND DEVICE FOR RECEIVING FREQUENCY DOMAIN MULTIPLEXED SIGNAL - A frequency domain multiplexed signal receiving method which decodes received signals that are multiplexed in a frequency domain, includes: a digital signal acquisition step of acquiring digital signals from the received signals that are multiplexed in the frequency domain; an offset discrete Fourier transform step of applying an offset discrete Fourier transform to odd discrete point numbers based on the acquired digital signals; and a decode step of decoding frequency domain digital signals in the frequency domain obtained by the offset discrete Fourier transform, and that are the frequency domain digital signals of one or more frequency channels. | 05-03-2012 |
20120307739 | SPATIAL MULTIPLEXING WIRELESS TRANSMISSION SYSTEM, SPATIAL MULTIPLEXING WIRELESS TRANSMISSION METHOD AND COMPUTER PROGRAM - A spatial multiplexing wireless transmission system is formed by a base station, and by a plurality of terminal stations that are provided with a plurality of antennas. The base station is provided with an information signal generating portion, a control signal generating portion, a transmission frame generating portion, a multiple beamforming portion, a transmission/reception switching portion, a reception signal processing portion, a propagation environment estimating portion, and an antenna information generating portion. At least one of the terminal stations is provided with a transmission/reception switching portion, a reception signal processing portion, a decoding portion, an antenna information extracting portion, an antenna information generating portion, an transmitting portion, a battery, a remaining battery detecting portion, a transmission request extracting portion, and a propagation environment estimating portion. | 12-06-2012 |
20120315043 | TRANSMISSION METHOD, RECEPTION METHOD, TRANSMITTER APPARATUS, AND RECEIVER DEVICE - A polarization state of a transmission signal can be changed at a high speed based on a symbol-rate By switching a first switch, a second switch, and a third switch with time, one of an X-polarized wave_I-signal as a Y-polarized wave_I-signal, a signal caused by performing logical inversion for an X-polarized wave_I-signal, an X-polarized wave_Q-signal and a signal caused by logical inversion for an X-polarized wave_Q-signal is input to a second modulator. Further, by switching the first switch, the second switch and the third switch with time, the second modulator is input one of the X-polarized wave_I-signal as the Y-polarized wave_Q-signal, the X-polarized wave_I-signal, the signal caused by performing logical inversion for the X-polarized wave_I-signal, the X-polarized wave_Q-signal and the signal caused by performing logical inversion for the X-polarized wave_Q-signal. Thereby, a polarization state of a transmission signal can be changed at high speed based on a symbol-rate speed. | 12-13-2012 |
20130028595 | FREQUENCY OFFSET ESTIMATING METHOD AND FREQUENCY OFFSET ESTIMATING APPARATUS - When a circuit that calculates a frequency offset using a shape of a frequency spectrum is implemented by hardware, the circuit size can be reduced. A frequency offset estimating method for estimating the difference between a carrier frequency of a reception signal and the frequency of an output signal of a local oscillator includes performing a discrete Fourier transform on a reception signal previously sampled at a predetermined sampling frequency and outputting a frequency spectrum with a plurality of frequency components, calculating an average power of the frequency spectrum, calculating a threshold by adding a predetermined value to the average power or power obtained by multiplying the average power by a constant, performing 1-bit quantization on powers of the frequency components of the frequency spectrum based on the threshold, and calculating a centroid frequency by multiplying frequencies of the frequency components by powers of 1-bit quantized frequency components, calculating the sum of multiplied products, and dividing the sum of the products by the sum of the powers of the 1-bit quantized frequency components of the frequency spectrum. | 01-31-2013 |
20130039205 | WIRELESS COMMUNICATION METHOD, BASE STATION, WIRELESS COMMUNICATION SYSTEM, AND COMMUNICATION APPARATUS - Provided are a wireless communication method, a base station, a wireless communication system and a communication apparatus whereby an interference power is calculated from an estimated propagation channel estimation result and the transmission power is controlled based on the interference power or the interference is suppressed by controlling the directivity, thereby increasing the transmission capacity. A propagation channel estimation circuit performs propagation channel estimation from a response signal transmitted from a terminal station and estimates a propagation channel estimation result. An interference power calculation circuit measures each interference power from a signal of each sub-carrier received by each of wireless units, and calculates an interference power for each sub-carrier from the propagation channel estimation result estimated by the propagation channel estimation circuit. When the calculated interference power is equal to or more than a predetermined threshold, an interference suppression signal generation circuit changes the transmission power and generates an interference suppression signal. | 02-14-2013 |
20130070874 | FREQUENCY OFFSET ESTIMATION APPARATUS, FREQUENCY OFFSET ESTIMATION METHOD, AND RECEPTION METHOD - Provided is a frequency offset estimation apparatus that appropriately estimates and compensates for a frequency offset of a received signal when estimating the frequency offset which is the difference between a carrier frequency of the received signal and the frequency of an output signal of a local oscillator. The frequency offset estimation apparatus converts the received signal sampled in advance with a predetermined sampling frequency into a frequency spectrum having N frequency components, limits a frequency band of negative frequency components from 1 to N/2 of the frequency spectrum and a frequency band of positive frequency components from N/2+1 to N of the frequency spectrum, calculates the sum of the squares of the positive frequency components of the frequency spectrum that have been subjected to frequency band limitation and the sum of the squares of the negative frequency components of the frequency spectrum that have been subjected to frequency band limitation to calculate power of the positive frequency components and power of the negative frequency components, and cyclically shifts all frequency components of the frequency spectrum in a frequency domain until the absolute value of a power difference between the power of the positive frequency components and the power of the negative frequency components is less than or equal to a predetermined threshold value, and estimates the frequency offset based on a shift amount until the absolute value is less than or equal to the threshold value. | 03-21-2013 |
20130208619 | WIRELESS COMMUNICATION SYSTEM AND WIRELESS COMMUNICATION METHOD - Communication quality is prevented from being deteriorated due to interference caused by low accuracy of channel information or interference from another base station or another wireless communication system. A wireless communication system includes a first wireless station including a plurality of antenna elements, transmission units corresponding to the plurality of antenna elements, and a transmission directivity control unit that controls transmission directivity of the plurality of antenna elements, and a plurality of second wireless stations each including a reception power measurement unit that measures a reception power. The transmission directivity control unit determines the transmission directivity of each of the plurality of antenna elements so that a signal does not reach a particular second wireless station among the plurality of second wireless stations. The transmission units generate wireless signals using the transmission directivity. The plurality of antenna elements transmit the generated wireless signals. The reception power measurement unit measures the reception power in a period that is set so that a signal does not reach the particular second wireless station, and detect the presence or absence of interference. | 08-15-2013 |
20130343749 | WAVELENGTH DISPERSION AMOUNT ESTIMATION METHOD, WAVELENGTH DISPERSION COMPENSATION CIRCUIT, AND RECEPTION DEVICE - A wavelength dispersion amount estimation method, a wavelength dispersion compensation circuit, and a receiving device which rapidly estimate and set a wavelength dispersion amount to compensate with high accuracy at the receiving device which compensates waveform distortion at an optical fiber transmission path. The wavelength dispersion compensation circuit includes an analog-digital converter which converts an optical analog waveform received from the optical fiber transmission path to a digital signal, a digital signal processor which compensates waveform distortion of the digital signal output from the analog-digital converter due to wavelength dispersion at the optical fiber transmission path with a dispersion compensation amount estimated with the wavelength dispersion amount estimation method, and a symbol clock extractor which extracts a symbol arrival timing clock of received data contained in the digital signal output from the analog-digital converter and outputs strength of the symbol arrival timing clock as the clock detection value. | 12-26-2013 |
20140016929 | METHOD FOR ESTIMATING AMOUNT OF WAVELENGTH DISPERSION, WAVELENGTH DISPERSION COMPENSATION CIRCUIT, AND RECEIVING DEVICE - A wavelength dispersion amount estimation method, a wavelength dispersion compensation circuit, and a receiving device which rapidly estimate and set a wavelength dispersion amount to compensate with high accuracy at the receiving device which compensates waveform distortion at an optical fiber transmission path. A wavelength dispersion compensation circuit includes an analog-digital converter which converts an optical analog waveform received from the optical fiber transmission path to a digital signal, a digital signal processor which compensates waveform distortion of the digital signal output from the analog-digital converter due to wavelength dispersion at the optical fiber transmission path with a dispersion compensation amount estimated with the wavelength dispersion amount estimation method, and a symbol clock extractor which extracts a symbol arrival timing clock of received data contained in the digital signal output from the analog-digital converter and outputs strength of the symbol arrival timing clock as the clock detection value. | 01-16-2014 |
20140050178 | WIRELESS COMMUNICATION SYSTEM AND ACCESS POINT APPARATUS - In a system which performs wireless communication from an access point to stations using group identification information, the frequency of uses of group identification information that overlaps with that of another access point is reduced. An association between a station apparatus included in a group that is a target for simultaneous transmission and group identification information is stored, each station apparatus included in the group is notified of the group identification information, group identification information that is being used in the other access point apparatus is acquired, and if group identification information that is being used by the access point apparatus itself overlaps with the group identification information used by the other access point apparatus, the group identification information is changed so as to reduce the number of pieces of overlapping group identification information. | 02-20-2014 |
20140204890 | WIRELESS COMMUNICATION METHOD AND ACCESS POINT APPARATUS - The number of training signals for channel estimation is reduced. A wireless communication method includes: a step of reading, by an access point apparatus, stored training weights for a station which performs channel estimation; a step of generating, by the access point apparatus, a weight training symbol by multiplying the training weights by a training symbol and transmitting the generated weight training symbol; a step of estimating, by a station apparatus, weight channel information from the received weight training symbol; a step of transmitting, by the station apparatus, the weight channel information to the access point apparatus; a step of calculating, by the access point apparatus, transmission weights using the received weight channel information and the stored training weights; a step of transmitting, by the access point apparatus, a data signal in accordance with the transmission weights; and a step of calculating and storing, by the access point apparatus, new training weights using the weight channel information and the stored training weights. | 07-24-2014 |
20140328280 | Radio Communication Method, Radio Communication System, Radio Base Station, and Radio Terminal Station - This radio communication method is used to perform spatial multiplexing communication between cells in the overlap cell environment. In the MU-MIMO overlap cell environment, when a null is formed between a radio base station and a radio terminal station belonging to different cells, a first set of a “call signal” and a “response signal” is used to perform mutual detection with the radio base station and the radio terminal station belonging to different cells, and then a null is formed so as not to cause interference of radio waves between the radio base station and the radio terminal station belonging to different cells. At this time, the addresses of the radio base station and the radio terminal station are used to discriminate whether the radio base station and the radio terminal station belong to the same cell or different cells. | 11-06-2014 |
20140376355 | WIRELESS APPARATUS AND TRAINING SIGNAL TRANSMISSION METHOD - The number of OFDM symbols for channel estimation is reduced, overhead due to a pilot signal and a feedback signal is reduced, and the throughput is improved. A wireless apparatus is provided with: an iterative coefficient setting unit which sets, for a plurality of transmission ports, an iterative coefficient representing the number of transmission ports which share a plurality of frequency channels of training signals for estimating the channel information; a training signal generating unit which allocates frequency channels to each transmission port so as to satisfy the set iterative coefficient and generates L training signals based on the allocated frequency channels; a channel information acquiring unit which acquires channel information estimated from the training signals from a communication partner for the frequency channels allocated to each transmission port; and a channel information interpolating unit which interpolates channel information of a remaining frequency channel other than the frequency channels allocated to each transmission port from the acquired channel information. | 12-25-2014 |
20140376535 | WIRELESS SIGNAL TRANSMITTING METHOD AND WIRELESS APPARATUS - Interference in preamble signals and pilot signals in cooperative transmission using interference suppressing technology is avoided. A wireless apparatus for transmitting a wireless signal on which directivity control has been performed to stations in a wireless system including at least one wireless apparatus is provided with a known signal generating unit which generates a known signal to be added to the wireless signal, a weighting processing unit which performs weighting on the known signal generated by the known signal generating unit, and a wireless processing unit which transmits the known signal on which the weighting has been performed by the weighting processing unit. | 12-25-2014 |
20150036634 | WIRELESS COMMUNICATION METHOD, BASE STATION, WIRELESS COMMUNICATION SYSTEM, AND COMMUNICATION APPARATUS - Provided are a wireless communication method, a base station, a wireless communication system and a communication apparatus whereby an interference power is calculated from an estimated propagation channel estimation result and the transmission power is controlled based on the interference power or the interference is suppressed by controlling the directivity, thereby increasing the transmission capacity. A propagation channel estimation circuit performs propagation channel estimation from a response signal transmitted from a terminal station and estimates a propagation channel estimation result. An interference power calculation circuit measures each interference power from a signal of each sub-carrier received by each of wireless units, and calculates an interference power for each sub-carrier from the propagation channel estimation result estimated by the propagation channel estimation circuit. When the calculated interference power is equal to or more than a predetermined threshold, an interference suppression signal generation circuit changes the transmission power and generates an interference suppression signal. | 02-05-2015 |
20150078762 | SIGNAL GENERATING CIRCUIT, OPTICAL SIGNAL TRANSMITTING APPARATUS, SIGNAL RECEIVING CIRCUIT, METHOD FOR ESTABLISHING OPTICAL SIGNAL SYNCHRONIZATION, AND OPTICAL SIGNAL SYNCHRONIZATION SYSTEM - To enable signal position detection, frequency offset compensation, clock offset compensation, and chromatic dispersion amount estimation in a communication system based on coherent detection using an optical signal, even on a signal having a great offset in an arrival time depending on a frequency due to chromatic dispersion. An optical signal transmitting apparatus generates specific frequency band signals having power concentrated on two or more specific frequencies and transmits a signal including the specific frequency band signals. An optical signal receiving apparatus converts a received signal into a digital signal, detects positions of the specific frequency band signals from the converted digital signal, estimates frequency positions of the detected specific frequency band signals, and detects a frequency offset between an optical signal receiving apparatus and an optical signal transmitting apparatus. Moreover, the optical signal receiving apparatus detects a clock offset between the optical signal receiving apparatus and the optical signal transmitting apparatus from an interval between the estimated frequency positions of the specific frequency band signals. Furthermore, the optical signal receiving apparatus estimates temporal positions of the detected specific frequency band signals and detects a chromatic dispersion amount from a difference between the temporal positions of the specific frequency band signals corresponding to different frequencies. | 03-19-2015 |
20150078765 | SIGNAL GENERATING CIRCUIT, OPTICAL SIGNAL TRANSMITTING APPARATUS, SIGNAL RECEIVING CIRCUIT, METHOD FOR ESTABLISHING OPTICAL SIGNAL SYNCHRONIZATION, AND OPTICAL SIGNAL SYNCHRONIZATION SYSTEM - To enable signal position detection, frequency offset compensation, clock offset compensation, and chromatic dispersion amount estimation in a communication system based on coherent detection using an optical signal, even on a signal having a great offset in an arrival time depending on a frequency due to chromatic dispersion. An optical signal transmitting apparatus generates specific frequency band signals having power concentrated on two or more specific frequencies and transmits a signal including the specific frequency band signals. An optical signal receiving apparatus converts a received signal into a digital signal, detects positions of the specific frequency band signals from the converted digital signal, estimates frequency positions of the detected specific frequency band signals, and detects a frequency offset between an optical signal receiving apparatus and an optical signal transmitting apparatus. Moreover, the optical signal receiving apparatus detects a clock offset between the optical signal receiving apparatus and the optical signal transmitting apparatus from an interval between the estimated frequency positions of the specific frequency band signals. Furthermore, the optical signal receiving apparatus estimates temporal positions of the detected specific frequency band signals and detects a chromatic dispersion amount from a difference between the temporal positions of the specific frequency band signals corresponding to different frequencies. | 03-19-2015 |