Abstract: The invention provides a power-line carrier communication apparatus including a transmission unit with a signal point mapping device for mapping a plurality of bit streams produced from transmission data, a wavelet inverse transforming device for modulating the respective sub-carriers by wavelet waveforms which are orthogonal to each other for producing temporal waveform series data, and a D/A converter for converting the temporal waveform series data into an analog temporal waveform series signal; and a reception unit with an A/D converter for obtaining sampling-series waveform data from a power-line communication signal, a wavelet transforming device for wavelet-transforming the sampling-series waveform data into signal point data of the respective sub-carriers, and a symbol judging device for judging bit streams mapped by the signal point mapping device by inverse-mapping a plurality of these signal point data, and for synthesizing the judged bit streams with each other as a reception data series.

Abstract: A relay apparatus includes a plurality of connecting terminals, such as a modem connecting terminal, a power line connecting terminal, an electric appliance connecting terminal and an antenna line connecting terminal; a selector that selects at least one connecting terminal from among the plurality of connecting terminals to transmit and receive a communication signal; and a control circuit that controls the selector. The relay apparatus further includes a first communication filter that passes signals in a frequency band used for communication by a power line communication modem and that blocks signals in other frequency bands, and a second communication filter that passes signals in a frequency band used for communication by another electric appliance and that blocks signals in other frequency bands.

Abstract: A coexistence controller which performs management and control of time division for coexistence, is provided in a power line communication modem which has a function as a QoS controller for a QoS type communication system and a power line communication modem for a best-effort type communication system. In the QoS type communication system, by controlling allocation of a communication band in accordance with priorities given to the communication systems by cooperation of the coexistence controller and the QoS controller, the power line communication systems having different schemes can coexist.

Abstract: A communication apparatus has a electrical outlet that is electrically connected to a power connector so as to supply power externally; a connection detector that detects connection of an external plug to the electrical outlet; and a controller that uses a receiver and a transmitter so as to perform setting with a device connected to the electrical outlet, when external connection is detected at the electrical outlet.

Abstract: A power line communication apparatus is provided with an auto gain detector that detects a gain fluctuation of an AGC (Auto Gain Control) circuit that automatically adjusts a gain of a received signal; a retry ratio calculator that calculates a ratio of retry based on output from an ARQ (Automatic Repeat request) unit that detects an error in the received data and issues a repeat request; and a transmission rate calculator that calculates a transmission rate based on output from a channel estimation unit that calculates a CNR so as to estimate a transmission status. A display displays a transmission status, including the detected AGC noise fluctuation, retry ratio, transmission rate and the like.

Abstract: A digital transmission signal from a digital signal processing unit is converted to an analog signal in an analog circuit, and is transmitted from transmission lines via a communication transformer. The digital signal processing unit includes a time carrier detector that detects a carrier by using a time waveform of a reception signal and a frequency carrier detector that detects a carrier by using frequency characteristics of the reception signal. Under the control of a controller, carrier detection is performed by switching between the time carrier detector and the frequency carrier detector for operation.

Abstract: A communication apparatus repeatedly outputs a first multi-carrier signal SS during predetermined periods T1, T2, T3, . . . , and outputs a second multi-carrier signal RS whose phase vector is different from that of the first multi-carrier signal SS, at a predetermined timing based on the first multi-carrier signal SS. The communication apparatus further detects the second multi-carrier signal RS output from another communication apparatus, which uses a different communication method from the communication apparatus. Accordingly, both communication apparatuses can differentiate the first multi-carrier signal SS from the second multi-carrier signal RS without performing relatively cumbersome modulation and other processes.

Abstract: A communication apparatus repeatedly outputs a first multi-carrier signal SS during predetermined periods T1, T2, T3, . . . , and outputs a second multi-carrier signal RS whose phase vector is different from that of the first multi-carrier signal SS, at a predetermined timing based on the first multi-carrier signal SS. The communication apparatus further detects the second multi-carrier signal RS output from another communication apparatus, which uses a different communication method from the communication apparatus. Accordingly, both communication apparatuses can differentiate the first multi-carrier signal SS from the second multi-carrier signal RS without performing relatively cumbersome modulation and other processes.

Abstract: A coexistence controller which performs management and control of time division for coexistence, is provided in a power line communication modem which has a function as a QoS controller for a QoS type communication system and a power line communication modem for a best-effort type communication system. In the QoS type communication system, by controlling allocation of a communication band in accordance with priorities given to the communication systems by cooperation of the coexistence controller and the QoS controller, the power line communication systems having different schemes can coexist.

Abstract: A frequency band is divided into N subchannels. Sub-channels are first allocated for a power line communication system having a higher priority, such as public communication or the like. Sub-channels for a power line communication system having a relatively low priority, such as in-home communication or the like, are allocated from free subchannels. In this case, the subchannels used by the power line communication system having the high priority are limited to a plurality of consecutive subchannels from an upper side or a lower side of the frequency band.

Abstract: A communication network system sets communication parameters which enable an operation under a maximum possible communication rate in a situation where a transmission path has cyclic noise/impedance fluctuations. A transmission/reception apparatus 100 transmits training packets for checking the state of the power line at two distinct points in time. A transmission/reception apparatus analyzes SNR at each carrier frequency, and stores an SNR evaluation result. The transmission/reception apparatus compares two SNR evaluation results which are obtained through two instances of a channel estimation algorithm, selects an SNR evaluation result which dictates a faster PHY rate, and transmits it to the transmission/reception apparatus. The transmission/reception apparatus changes modulation/demodulation rules based on the received SNR analytical result.

Abstract: A power line communication apparatus is provided with an auto gain detector that detects a gain fluctuation of an AGC (Auto Gain Control) circuit that automatically adjusts a gain of a received signal; a retry ratio calculator that calculates a ratio of retry based on output from an ARQ (Automatic Repeat request) unit that detects an error in the received data and issues a repeat request; and a transmission rate calculator that calculates a transmission rate based on output from a channel estimation unit that calculates a CNR so as to estimate a transmission status. A display displays a transmission status, including the detected AGC noise fluctuation, retry ratio, transmission rate and the like.

Abstract: A communication apparatus repeatedly outputs a first multi-carrier signal SS during predetermined periods T1, T2, T3, . . . , and outputs a second multi-carrier signal RS whose phase vector is different from that of the first multi-carrier signal SS, at a predetermined timing based on the first multi-carrier signal SS. The communication apparatus further detects the second multi-carrier signal RS output from another communication apparatus, which uses a different communication method from the communication apparatus. Accordingly, both communication apparatuses can differentiate the first multi-carrier signal SS from the second multi-carrier signal RS without performing relatively cumbersome modulation and other processes.

Abstract: Provided is a multi-carrier communication apparatus, power line communication circuit, and multi-carrier communication method capable of decreasing omission of carrier detection even when a plurality of communication apparatuses are simultaneously transmitting signals at the state of time discord. Digital signals transmitted from a digital signal-processing unit 1 are converted into analog signals by an analog circuit unit 2 and then transmitted from a pair of lines 61 and 62 via a communication transformer 3. The digital signal-processing unit 1 has a frequency carrier detecting unit 10 which detects the existence of a carrier on the basis of a frequency characteristic of the received signal and the frequency carrier detecting unit 10 detects the carrier by taking correlation between sub-carriers adjacent to each other at every other interval.

Abstract: A PLC modem performs communication via transmission lines made of a pair of cables as an example of a wired transmission line. Data displaying an operation state of the PLC modem is transmitted to a light emitting part via a modulator, and is converted into a high-speed flash signal for output.

Abstract: A diversity circuit uses a plurality of sub-carriers showing CINRs below a lowest threshold, so as to form a sub-carrier group so that combined CINR of the sub-carriers is above the lowest threshold. A diversity tone map generator generates a tope map associated with the lowest primary modulation scheme, based on output from the diversity circuit. A tone map generator generates a tone map associated with primary modulation schemes applied to respective sub-carriers, based on output from the diversity tone map generator.

Abstract: A frequency band is divided into N subchannels. Sub-channels are first allocated for a power line communication system having a higher priority, such as public communication or the like. Sub-channels for a power line communication system having a relatively low priority, such as in-home communication or the like, are allocated from free subchannels. In this case, the subchannels used by the power line communication system having the high priority are limited to a plurality of consecutive subchannels from an upper side or a lower side of the frequency band.

Abstract: A multicarrier communication method selects carriers on the basis of an SN-ratio and the balancing of a transmission line. Available carriers are selected in accordance with the balancing of the balanced transmission line, in which the balancing is measured at either a sending terminal or a receiving terminal or alternatively at both, and the SN-ratio is measured between the sending terminal and the receiving terminal. Additionally, a modulation method having the greatest permissible multivalue is selected for each of the carriers, wherein the carriers are selected in light of the SN-ratio and balancing, or alternatively in a highest-to-lowest order of frequency. Transmission power is controlled for each of the carriers to suppress radiated emission, and the SN-ratio and balancing are measured at predetermined time intervals to renew the selection of the carriers and the selection of the modulation methods.

Abstract: The invention provides a power-line carrier communication apparatus including a transmission unit with a signal point mapping device for mapping a plurality of bit streams produced from transmission data, a wavelet inverse transforming device for modulating the respective sub-carriers by wavelet waveforms which are orthogonal to each other for producing temporal waveform series data, and a D/A converter for converting the temporal waveform series data into an analog temporal waveform series signal; and a reception unit with an A/D converter for obtaining sampling-series waveform data from a power-line communication signal, a wavelet transforming device for wavelet-transforming the sampling-series waveform data into signal point data of the respective sub-carriers, and a symbol judging device for judging bit streams mapped by the signal point mapping device by inverse-mapping a plurality of these signal point data, and for synthesizing the judged bit streams with each other as a reception data series.

Abstract: Channel estimation unit 16 includes CNR calculation unit 17, threshold setting unit 18, and modulation method determination unit 19. CNR calculation unit 17 calculates a CNR for each of a plurality of subcarriers from a received multicarrier communication signal. Threshold setting unit 18 takes statistics of a plurality of calculated CNRs, and, based on the statistics, sets CNR thresholds each assigned to one of a plurality of modulation methods. Modulation method determination unit 19 uses the set thresholds to determine a modulation method for each subcarrier, according to the calculated CNR of the subcarrier.