Abstract: Multi-carrier transmission is performed without inserting a repetitive signal into guard interval periods. A transmitter provides guard interval periods by using a null signal to save transmission power and prevent the deterioration of the SN ratio. Delayed waves at the head of each received symbol cause high-frequency waves to occur and carriers to interfere with one another. Accordingly, a receiver adds a component following each received symbol to a delayed-wave component at the head of the received symbol. As a result, the delayed-wave component at the head of the received symbol and the added component become continuous in wave form and subcarriers do not interfere with each other.

Abstract: In a wireless communication system with a periodical frame structure, as a method for transmitting information using an allocated channel over a plurality of frames by a single channel allocation request, an allocated channel is released when transmission is terminated or when a communication apparatus is disconnected from a network, and a channel can be allocated over a plurality of continuous frames.

Abstract: Each wireless communication apparatus forming a wireless network has an operation mode in which a wireless communication apparatus becomes a control station with priority, an operation mode in which a wireless communication apparatus may operate as a control station, and an operation mode in which a wireless communication apparatus does not become a control station. By providing a function in which a user selects and sets one of these three operation modes, the wireless network can be constructed as desired by the user. As a result of providing the mode in which the wireless communication apparatus does not become a control station, a wireless communication apparatus that is connected to a device but that cannot operate as a control station is not specified as a control station. Therefore, by allowing a specific apparatus in the wireless network to function as a control station, the wireless network can be constructed.

Abstract: Disclosed is a method that preferably performs transmission processing to a time sequence signal of a known pattern as the pre-amble and an OFDM transmitted signal. In data communications, the general practice defines the pre-amble and detects the peaks of the mutual correlation to thereby detect synchronization. The pre-amble here is defined by the binary value in most cases for simplification of a correlation detecting device. In this case, the spectrum becomes irregular with sharp peaks and dips, which deteriorates the correlation characteristic. The method of the invention forcibly adjusts the spectrum amplitude of the pre-amble pattern on the transmitting side while retaining the phase information thereof, and thereby the method improves the spectrum and correlation characteristics while securing simplification of a correlation detecting device on the receiving side.

Abstract: Method and apparatus for sending and receiving pulses in the ultra wide band communication system while avoiding spectrum problems. Carrier waves, for example, are generated with a frequency set in the center of the transmission band of 7.5 GHz to avoid the 5 GHz currently used by wireless LAN systems and frequencies below 3 GHz specified for spectrum mask by the FCC. Baseband pulses are then generated at time intervals equal to a fraction 1/n of this frequency (n is an integer). The baseband pulses are rectangular waves with a length that is an integer multiple of one period of the carrier wave on the specified frequency. Finally 3-cycle pulses are made by frequency-modulating the baseband pulses with the carrier waves.

Abstract: A system and method for performing ranging and positioning as follows by using the procedure for packet transmission and reception between a sender and a recipient. A first radio set transmits packets to a second radio set as a recipient. The second radio set returns the packets without fail after the lapse of time (from the detection of packets) which corresponds to an integral multiple of a prescribed unit time. The first radio set counts, by using its counter, the time which has elapsed from its transmission of packets to its detection of packets from the second radio set. The remainder of the thus counted time after subtraction of the time taken by the second radio set from packet detection to packet return and the processing time of the first radio set itself is converted into the distance of propagation between the first radio set and the second radio set as a recipient.

Abstract: A communications system sets a network frame period that can be repeatedly used by a plurality of wireless networks in a predetermined time period. A plurality of channel slots for use by each of the wireless networks is prepared in advance in the network frame. A coordinator operating a PAN activates its PAN in an area of a channel slot that is not used by the other coordinator(s). Since each of the wireless networks detects an unused channel slot in the network frame and uses the unused channel slot, the association process is greatly simplified.

Abstract: A laser beam direct imaging apparatus and an imaging method which can precisely determine a back-surface-side position with respect to a front-surface-side position even if any kind of photosensitive material is used. In the laser direct imaging apparatus, a laser beam is deflected toward a main scanning direction (X-axis direction) while a workpiece mounted on a table is moved in a sub-scanning direction (Y-axis direction) so that a pattern is imaged on the surface of the workpiece. Hollow pins are disposed on the table so that the tips of the hollow pins 20 project over the surface of the table by a predetermined distance. The workpiece is sucked onto the table so that indentations (indentations by the tips of the hollow pins) are formed on the back surface of the workpiece. When a pattern is imaged on the back surface, imaging is performed with reference to the indentations.

Abstract: A receiver performs an inverse Fast Fourier Transform (FFT) on a plurality of carriers to receive an Orthogonal Frequency Division Multiplexing (OFDM) signal to be transmitted by converting a signal along a frequency-domain into a signal along a time-domain. The receiver includes a frequency response acquisition section configured to acquire a frequency response from the received OFDM signal. The receiver also includes a smoothing section configured to produce a smoothed frequency response from the frequency response, a decimation section configured to decimate a number of points from the smoothed frequency response to produce a decimated frequency response including points corresponding to a path that is reached first, and a time response acquisition section configured to acquire a time response from the decimated frequency response including the points corresponding to the path that is reached first.

Abstract: A laser direct imaging apparatus which can expose photosensitive materials having various sensitivities and which can correct an imaging position in accordance with deformation of a workpiece. In the laser direct imaging apparatus, the workpiece is moved in a sub-scanning direction while a cylindrical lens is used to converge a laser beam, which has been modulated based on raster data, in the sub-scanning direction and deflect the laser beam toward a main scanning direction so as to image a desired pattern on the workpiece. The cylindrical axis of the cylindrical lens is designed to be able to rotate horizontally and to be able to change an angle with respect to the main scanning direction.

Abstract: A radio communication network that requires no connection between base stations during handoff or when the cell is overloaded, is realized by using a receiver that has a multi-user detection function and a transmitter for synthesizing control information and user data to output the synthesized data. Upon reception of a signal that is transmitted from a mobile station located on the boundary with a neighboring cell, the base station synthesizes user data for a mobile station in its local cell and control information for controlling the handoff operation to transmit the synthesized data. In response to this transmission, a mobile station in the neighboring cell separates the control information by multi-user detection to detect the signal and transmits a handoff request to the base station.

Abstract: In the case where there is a conflict over a band between communication stations that have reserved the band, the communication stations mediate and avoid the conflict of reservation use with low-load processing. In a wireless communication system, band reservation use is permitted, and a plurality of reservation types are provided according to priority of communication. A communication station that performs reservation use describes a reservation type and a rock-paper-scissors value in a beacon. When there occurs a conflict of reservation use at some area, reservation use having higher priority remains, and a communication station that has performed reservation use having a lower priority moves it to another area. In the case where there is a conflict between reservations having the same priority, the communication apparatuses that have performed reservation use perform control by rock-paper-scissors between themselves, and move the reservation of the apparatus that has lost by the judgment.

Abstract: A transmitting apparatus, receiving apparatus, communication system, and a signal processing method for each apply a suitable modulation method and transmission path estimation method in accordance with the characteristics of the transmission information and capable of improving the transmission efficiency. At the transmission side, the method of estimation of the transmission path and the modulation method are selected in accordance with an attribute of the data to be transmitted, for example, the size of a packet to be transmitted, the transmission data is mapped by the selected modulation method, the signal is processed in accordance with the transmission path estimation method, and a transmission signal is created by increase fast Fourier transform processing and transmitted.

Abstract: A system and method for performing ranging and positioning as follows by using the procedure for packet transmission and reception between a sender and a recipient. A first radio set transmits packets to a second radio set as a recipient. The second radio set returns the packets without fail after the lapse of time (from the detection of packets) which corresponds to an integral multiple of a prescribed unit time. The first radio set counts, by using its counter, the time which has elapsed from its transmission of packets to its detection of packets from the second radio set. The remainder of the thus counted time after subtraction of the time taken by the second radio set from packet detection to packet return and the processing time of the first radio set itself is converted into the distance of propagation between the first radio set and the second radio set as a recipient.

Abstract: A transmitting station side transmits a transmitting signal obtained by a process of segmenting transmission information into a plurality of frames, of encoding each frame, of power amplifying each encoded signal with different amplitude, and of interleaving all signals with each amplitude signal collected into one. A receiving station side reproduces of the above transmitting signal into original segmental frames by a process of de-interleaving the above transmitting signal, of successively decoding codes of the signal in descending order of SINR, and of re-encoding the decoded signal to successively cancel the re-encoded signal from the above transmitting signal.

Abstract: An inner-space-sectioned tube wherein, in manufacturing the tube having four or more independent fluid channels formed inside thereof, while at least two lengths of inner tubes are set to inscribe an outer tube, cold working is applied, which is a simple manufacturing process, thereby enabling to reduce the number of cold drawing passes and allowing the inner space of the tube, even if the outer tube is small in size, to effectively be allocated for four independent fluid channels. Further, this inner-space-sectioned tube adopts a simple tube structure wherein the number of constituting members is reduced, thereby enabling to reduce weight while ensuring tube strength and to achieve further reduction of manufacturing costs.

Abstract: There is provided a communication apparatus compliant with ultra wide band communication systems for improving resistance to interfering waves in combination with DS-SS (direct sequence spread spectrum). There is provided a training section based on short code spread with the same pattern repeated for each symbol length. Actual communication itself is preceded by coherent channel measurement of a transmission channel by using the training section to specify a length of the short code to be a measurement period and using N cycles of a carrier as a time resolution for measurement. A chip timing is controlled at the time resolution for measurement. At all points given by a time resolution for a measurement period, a measured value is obtained by using the short code to despread A/D-converted values from an input signal based on the chip timing.

Abstract: A communication device configured to perform packet reception processing, with the header of a packet including a header sequence and a Reed-Solomon code, includes: a header check sequence inspecting unit configured to detect, based on the header check sequence included in a received packet header, an error of the header; a Reed-Solomon encoding unit configured to encode the header of a received packet other than the Reed-Solomon code to generate a Reed-Solomon code; a Reed-Solomon code inspecting unit configured to detect whether or not the Reed-Solomon code generated by the Reed-Solomon encoding unit is completely identical to the Reed-Solomon code within the received packet header; and a processing control unit configured to control payload processing of a received packet in accordance with the inspection results of the header check sequence inspecting unit and the Reed-Solomon code inspecting unit.

Abstract: There is provided a communication apparatus compliant with ultra wide band communication systems for improving resistance to interfering waves in combination with DS-SS (direct sequence spread spectrum). There is provided a training section based on short code spread with the same pattern repeated for each symbol length. Actual communication itself is preceded by coherent channel measurement of a transmission channel by using the training section to specify a length of the short code to be a measurement period and using N cycles of a carrier as a time resolution for measurement. A chip timing is controlled at the time resolution for measurement. At all points given by a time resolution for a measurement period, a measured value is obtained by using the short code to despread A/D-converted values from an input signal based on the chip timing.

Abstract: A transmitter and receiver carry out ultra wideband communications. The transmitter includes a generator of a chip clock, a generator of a spreading code sequence of a fixed chip rate by using the chip clock, and a frequency converter of a carrier wave frequency, being synchronous with the chip clock, by a transmission signal spread-modulated by the spreading code sequence. The receiver includes a generator of a chip clock synchronous in timing with a received signal, a generator of a spreading code sequence of a fixed chip rate by using the chip clock, a frequency converter of the received signal by using a regenerated carrier wave signal synchronous with the chip clock, and a despreading unit of the received signal frequency-converted by using the spreading code sequence.