Abstract: According to one embodiment, a wireless communication device includes: a communicator and controlling circuitry. The communicator is configured to simultaneously communicate a first frame and a second frame, and after the first frame and the second frame are communicated, communicate a third frame indicating acknowledgement of the first frame and a fourth frame indicating acknowledgement of the second frame. The controlling circuitry is configured to control to prevent the third frame and the fourth frame from being simultaneously communicated.

Abstract: To save power consumed due to reception of frames destined to other communication devices and enable power saving by prolonging a sleep state. A communication device is provided including a communication unit which communicates with a base station, a switching unit which switches an operation mode of the communication unit from a normal mode for communicating with the base station to a power saving mode for uncommunicating with the base station, when the communication unit receives data from the base station in a state in which the communication unit does not transmit a data transmission request to the base station, and a determination unit which determines a duration time of the power saving mode, based on a data length of the data received.

Abstract: There is provided a wireless communication control device and a wireless communication control method, which control the transmission power of radio waves of base stations appropriately to reduce interference between cells. The wireless communication control method according to the present invention is a method of controlling plural base stations in a wireless communication system in which the plural base stations cover a target area with radio waves of a first radio wave strength or more, the method causing a computer to execute: a step of acquiring a relative positional relationship of the plural base stations; a step of identifying a base station, located in the neighborhood of the boundary of the target area, from the relative positional relationship of the plural base stations; and a step of lowering the transmission power of radio waves of a base station other than the identified base station among the plural base stations.

Abstract: There is provided a wireless communication control device and a wireless communication control method, which control the transmission power of radio waves of base stations appropriately to reduce interference between cells. The wireless communication control method according to the present invention is a method of controlling plural base stations in a wireless communication system in which the plural base stations cover a target area with radio waves of a first radio wave strength or more, the method causing a computer to execute: a step of acquiring a relative positional relationship of the plural base stations; a step of identifying a base station, located in the neighborhood of the boundary of the target area, from the relative positional relationship of the plural base stations; and a step of lowering the transmission power of radio waves of a base station other than the identified base station among the plural base stations.

Abstract: According to one embodiment, a wireless communication device includes: a communicator and controlling circuitry. The communicator is configured to simultaneously communicate a first frame and a second frame, and after the first frame and the second frame are communicated, communicate a third frame indicating acknowledgement of the first frame and a fourth frame indicating acknowledgement of the second frame. The controlling circuitry is configured to control to prevent the third frame and the fourth frame from being simultaneously communicated.

Abstract: To save power consumed due to reception of frames destined to other communication devices and enable power saving by prolonging a sleep state. A communication device is provided including a communication unit which communicates with a base station, a switching unit which switches an operation mode of the communication unit from a normal mode for communicating with the base station to a power saving mode for uncommunicating with the base station, when the communication unit receives data from the base station in a state in which the communication unit does not transmit a data transmission request to the base station, and a determination unit which determines a duration time of the power saving mode, based on a data length of the data received.

Abstract: A power line communication system is provided in which the influence of the impulsive noise unexpectedly generated on a power line which is a communication medium can be reduced according to the characteristics of the impulsive noise by an existing method and power line communication can be realized without a hindrance. A transmitter is constituted by: a modulator for conveying a LIN data signal by a power line; a filter that allows a signal of a predetermined band to pass therethrough; and a sinusoidal wave outputter (sinusoidal wave in the figure). In contrast, the receiver is constituted by the sinusoidal wave outputter, the filter and a demodulator that performs demodulation. To the power line, a limiter that limits the amplitude of the propagating signal to a predetermined amplitude (reception signal amplitude) is connected.

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.

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.

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.

Abstract: A power line communication system is provided in which the influence of the impulsive noise unexpectedly generated on a power line which is a communication medium can be reduced according to the characteristics of the impulsive noise by an existing method and power line communication can be realized without a hindrance. A transmitter is constituted by: a modulator for conveying a LIN data signal by a power line; a filter that allows a signal of a predetermined band to pass therethrough; and a sinusoidal wave outputter (sinusoidal wave in the figure). In contrast, the receiver is constituted by the sinusoidal wave outputter, the filter and a demodulator that performs demodulation. To the power line, a limiter that limits the amplitude of the propagating signal to a predetermined amplitude (reception signal amplitude) is connected.

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.

Abstract: In an OFDM packet communication receiver, the deterioration of received signal quality is suppressed, even when carrier frequency error and/or clock frequency error exists between a transmitter and a receiver, and/or phase noise and/or thermal noise is superimposed to a received signal in a receiver.

Abstract: A preamble for synchronization, or a reference timing for operation of an OFDM packet communication receiver system is detected finely even under environment of large waveform distortion due to thermal noise and/or multi-path propagation, and/or large carrier frequency offset between a transmit side and a receiver side. A correlator (1) detects a pattern of a short preamble (t1-t10) in a preamble for synchronization. An output of the correlator (1) is applied to a complex filter (7) which separates a short preamble having a predetermined repetition period from uniformly distributed noise. A scalar filter (9) integrates some period of short preambles which have distributed-delay by multi-path propagation as if a single short preamble with no delay were received for determining a reference timing.

Abstract: A coherent detection system for multicarrier modulation system capable of accurate channel estimation even in severe environment with high thermal noise and deep multipath fading, has been found with simple structure and small circuit size. The present coherent detection system comprises a channel estimation circuit (208) for estimating a channel attenuation of a preamble part of each subcarriers, an adaptive filter (210, 211) for smoothing estimated channel attenuation among subcarriers, a divider (213) for coherent detection of a data part by dividing a receive vector by smoothed estimated channel attenuation for each subcarriers, and a characteristic extraction circuit (209) for extracting characteristic value of each subcarriers. The adaptive filter (210, 211) is controlled depending upon characteristic value of each subcarriers measured by the characteristic extraction circuit (209).

Abstract: A method of packet transfer is provided to resolve the problem of fraudulent access to user LANs through falsified source address so that only those pre-registered terminals are permitted to transfer packets with specific data networks. Each user LAN is assigned an identifier to identify respective user LAN beforehand. Packet network stores terminal information including terminal addresses, identifiers assigned to one and more user LANs that are permitted to communicate with each packet terminal and information necessary for terminal authentication beforehand. When the packet terminal starts a communication through a base station, the packet network authenticates the packet terminal, and if it is an unauthorized terminal, the packet network informs a denial for communication to the packet terminal.

Abstract: A digital communication system using superposed transmission of high and low speed digital signals capable of transmitting superposed high and low speed digital signals through an identical frequency band efficiently by increasing a simultaneously transmittable number of channels in the low speed digital signals, while achieving the practically reasonable bit error rate performances for both the high speed digital signals and the low speed digital signals.

Abstract: An improved oscillator which can adjust phase and frequency of the output signal independently from each other without time delay is disclosed. The oscillator is used for instance as a clock signal generator in a TDMA satellite communication system. The oscillator (FIG. 3) comprises a fixed oscillator (13) for providing a fixed frequency signal, a quadrature hybrid circuit (14) for providing a pair of quadrature phased signals from the output of said fixed oscillator (13), a control signal generator (17) for providing a pair of quadrature phased signals which satisfy b cos (2.pi..DELTA.f.sub.D t+.DELTA..phi..sub.D) and b sin (2.pi..DELTA.f.sub.D t+.DELTA..phi..sub.D), where b is a constant, .DELTA.f.sub.D is a desired frequency change, and .DELTA..phi..sub.