Abstract: A packet processing apparatus includes a memory configured to store, for each time slot number, switching information for switching output of a packet of each packet type, a counter configured to count the time slot number, an output control circuit configured to control the output, based on the switching information that corresponds to the time slot number currently counted, a transmitter configured to transmit a control packet for resetting the time slot number currently counted in each packet processing apparatus in a set path, in a predetermined direction of the set path in accordance with a predetermined timing, and a reset circuit configured to, in response to a start of a transmission of the control packet, reset the time slot number currently counted and restart a count operation of the counter.

Abstract: A frame transmission system includes a frame transmitter and a frame receiver. The frame transmitter includes a frame fragmentation unit and a reproduction header appending unit. The frame fragmentation unit fragments an input frame and outputs transfer frames when the length of the input frame exceeds a predetermined fragmentation reference frame length, and does not fragment the input frame and outputs the input frame as a transfer frame when the length of the input frame is less than or equal to the fragmentation reference frame length. The reproduction header appending unit appends a reproduction header to the transfer frames outputted from the frame fragmentation unit. Here, the reproduction header being required when the transfer frames are reproduced at a receiving side. The reproduction header appending unit varies the header length of the reproduction header to be appended to the transfer frame, according to the length of the input frame.

Abstract: A frame transmission system includes a frame transmitter and a frame receiver. The frame transmitter includes a frame fragmentation unit and a reproduction header appending unit. The frame fragmentation unit fragments an input frame and outputs transfer frames when the length of the input frame exceeds a predetermined fragmentation reference frame length, and does not fragment the input frame and outputs the input frame as a transfer frame when the length of the input frame is less than or equal to the fragmentation reference frame length. The reproduction header appending unit appends a reproduction header to the transfer frames outputted from the frame fragmentation unit. Here, the reproduction header being required when the transfer frames are reproduced at a receiving side. The reproduction header appending unit varies the header length of the reproduction header to be appended to the transfer frame, according to the length of the input frame.

Abstract: Disclosed are a radio terminal device and the like, which achieve an improvement in the accuracy of ranging between a UWB reader and a UWB tag regardless of whether an active method or a semi-passive method. In a terminal (300), a timing control unit (340) outputs, to a transmission amplifier (350), a control signal for performing on-off control such that on the basis of the reception timing of a pulse signal transmitted from a base station (200) and a representative value of a circuit delay time required from when a reception pulse signal is received until a transmission pulse signal generated in response to a detection signal of the reception pulse signal is transmitted, the transmission amplifier (350) amplifies a reradiation pulse generated in response to a detection signal of the pulse signal transmitted from the base station (200); and a re-reradiation pulse generated in response to a detection signal of the reradiation pulse.

Abstract: Provided is an array signal processing device capable of, when a spatial averaging method is applied to array signal processing, reducing the number of antennas constituting an array antenna while making use of the spatial averaging method. In the array signal processing device (300), an array antenna (310) comprises four antennas (311-1 to 311-4) disposed at the four vertices of a parallelogram. Correlation calculation units (341-1, 2) calculate, based on a received signal, spatial correlation matrices for respective sub-array antenna (312-1) and sub-array antenna (312-2), the sub-array antenna (312-1) comprising the antennas (311-1, 3) disposed at the opposing two vertices and the antenna (311-2), the sub-array antenna (312-2) comprising the antennas (311-1, 3) and the antenna (311-4). An array rotation unit (342) converts a first spatial matrix of the calculated two spatial matrices to the complex conjugate thereof.

Abstract: Provided are a distance measuring device and a distance measuring method which can easily distinguish a reflected signal from a desired tag from an unnecessary wave so as to improve the distance measuring accuracy even when IR-UWB is used for measuring a distance. The method uses a reader ID indicated by a code string formed by P bits (P is a natural number) for identifying a base station and a tag ID indicated by a code string formed by Q bits (Q is a natural number) for identifying a radio terminal. The method generates a unique word containing P pulses, each of which is ON/OFF-modulated depending on whether each of P bits indicating the reader ID is 1 or 0. The method generates a frame containing 2 M unique words and a burst containing Q frames. The method further outputs a transmission signal containing a plurality of bursts. A radio terminal Amplitude Shift Keying (ASK)—modulates the transmission signal depending on whether each of the Q bits indicating the tag ID is 1 or 0.

Abstract: The number of data frames transmitted between two apparatuses is counted by a transmission counter, while the number of received frames is counted by a reception counter. When an OAM frame for frame loss measurement is transmitted, the value of the transmission counter is cached in a cache memory. At the time of generation of an OAM frame at an OAM frame generation unit, the value of the cache memory is used so as to generate an OAM frame carrying the value of the transmission counter at the time of transmission of the OAM frame transmitted previously. The frame loss is calculated from the difference of the value of the transmission counter carried in the OAM frame from the previous value and the difference of the value of the reception counter at the time of reception of the previous previous OAM frame from the previous value.

Abstract: A device for estimating a direction-of-arrival of a radio wave, the device comprising an array antenna including a plurality of antenna elements for receiving a high frequency signal, a demultiplexer for demultiplexing the received high frequency signal for each of the plurality of antenna elements to generate a plurality of frequency component signals and a direction estimating unit for estimating the direction-of-arrival of the radio wave by using two or more of the plurality of frequency component signals which are contiguous in a frequency direction.

Abstract: A receiver having an array antenna estimates arrival directions of multiple paths that arrive with an angular spread. Consequently, arrival direction estimation accuracy can be ensured without increasing throughput even if the power every path is low by estimating an average arrival direction of an entire set of multiple paths having the angular spread from a result of one angular spectrum by multiple correlation operation units that perform mutual correlation operations with pilot signals for baseband signals received by the array antenna, a path detection unit that detects multiple arrival path receiving timings by generating a delay profile based on output of each of the correlation operation units, a path correlation value synthesis unit that synthesizes a correlation operation value calculated in the multiple correlation operation units and an arrival direction estimation unit that collectively estimates multiple path arrival directions using output of the path correlation value synthesis unit.

Abstract: A receiver having an array antenna estimates arrival directions of multiple paths that arrive with an angular spread. Consequently, arrival direction estimation accuracy can be ensured without increasing throughput even if the power every path is low by estimating an average arrival direction of an entire set of multiple paths having the angular spread from a result of one angular spectrum by multiple correlation operation units that perform mutual correlation operations with pilot signals for baseband signals received by the array antenna, a path detection unit that detects multiple arrival path receiving timings by generating a delay profile based on output of each of the correlation operation units, a path correlation value synthesis unit that synthesizes a correlation operation value calculated in the multiple correlation operation units and an arrival direction estimation unit that collectively estimates multiple path arrival directions using output of the path correlation value synthesis unit.

Abstract: Wireless communication apparatus adopting a time division duplex system for transmission and reception using plural antennas, deviation of amplitude and phase occurring between transmission and reception circuits is detected and corrected using a communication signal. Channel estimation means detects channel information based on reception output of N reception circuits having a one-to-one correspondence with N antennas. Correction value detection means finds a correction value for correcting deviation occurring between each of N transmission circuits and each of the N reception circuits based on the channel information. A wireless communication apparatus transmits an already known signal (training signal) to a base station with which the wireless communication apparatus conducts communications. The base station executes channel estimation based on the already known signal and generates and transmits a correction signal (probe signal).

Abstract: A radio arrival direction estimation device that accurately estimates the arrival direction of radio waves from a desired tag, even when there are multiple antennas disposed at short intervals. When ID detection timing is provided from a timing detector (114) to a switch (201), relative amplitude/phase data related to the tag ID digital value “1” or “0” is obtained by an arrival direction estimation unit (125). One relative amplitude/phase datum is formed for each unit cycle in a first adder (202), which adds the relative amplitude/phase datum related to the tag ID digital value “1” to each element in a matrix, and a second adder (203), which adds the relative amplitude/phase datum related to the tag ID digital value “0” to each element in a matrix.

Abstract: Wireless communication apparatus adopting a time division duplex system for transmission and reception using plural antennas, deviation of amplitude and phase occurring between transmission and reception circuits is detected and corrected using a communication signal. Channel estimation means detects channel information based on reception output of N reception circuits having a one-to-one correspondence with N antennas. Correction value detection means finds a correction value for correcting deviation occurring between each of N transmission circuits and each of the N reception circuits based on the channel information. A wireless communication apparatus transmits an already known signal (training signal) to a base station with which the wireless communication apparatus conducts communications. The base station executes channel estimation based on the already known signal and generates and transmits a correction signal (probe signal).

Abstract: Provided is a MIMO communication device which can maintain the MIMO communication characteristic at a certain level regardless of the device installation position. The MIMO communication device (100) includes antenna elements (101-1, 101-2) as a first and a second antenna element which are arranged on a single straight line and an antenna element (102-1) or an antenna element (102-2) as a third antenna element which is arranged out of the straight line. A MIMO modulation unit (105) is connected to all the antenna elements. This assures that there exists a combination of antennas having other than 0 as a matrix expression of a channel estimation matrix in a propagation path between the MIMO communication device (100) and the communication partner regardless of the installation position of the MIMO communication device (100) with respect to a communication partner.

Abstract: A radio positioning system includes a plurality of base stations and a radio terminal. Each of the base stations includes a reference signal generating portion which generates a reference signal for positioning, a transmission portion which transmits the reference signal, a reception portion which receives a signal from its outside, a positioning portion which calculates a position relative to the radio terminal or base station as a signal sender based on the received signal, and a reference signal return portion which receives a reference signal transmitted from another base station and returns the reference signal to the another base station. The radio terminal includes a terminal reception portion which receives the reference signal, and a terminal transmission portion which returns the received reference signal.

Abstract: In a wireless communication apparatus adopting a time division duplex system for executing transmission and reception using a plurality of antennas, deviation of amplitude and phase occurring between transmission and reception circuits is detected and corrected using a communication signal. Channel estimation means 105 detects channel information based on reception output of reception circuits 104-1 to 104-N provided in a one-to-one correspondence with a plurality of antennas 101-1 to 101-N. Correction value detection means 110 finds a correction value for correcting deviation occurring between each of transmission circuits 103-1 to 103-N and each of the reception circuits 104-1 to 104-N based on the channel information. A wireless communication apparatus 100 transmits an already known signal (training signal) to a base station with which the wireless communication apparatus conducts communications.

Abstract: A wireless distance measurement system and wireless terminal improve the accuracy of distance measurement when the UWB communication scheme is used. In wireless terminal 200, a route of signals varies between a distance measuring operation and a synchronization establishing operation, and, when the distance measuring operation is performed, a detection result is inputted to comparator 208 without passing through integrator 204. By this means, the distance measuring operation of wireless terminal 200 does not involve integration processing, so that delay time due to integration processing is not produced and, consequently, it is possible to improve the accuracy of distance measurement. Further, the distance measuring operation uses the integration result acquired integrator 204 for a comparison reference voltage used in comparator 208.

Abstract: Disclosed are a radio terminal device and the like, which achieve an improvement in the accuracy of ranging between a UWB reader and a UWB tag regardless of whether an active method or a semi-passive method. In a terminal (300), a timing control unit (340) outputs, to a transmission amplifier (350), a control signal for performing on-off control such that on the basis of the reception timing of a pulse signal transmitted from a base station (200) and a representative value of a circuit delay time required from when a reception pulse signal is received until a transmission pulse signal generated in response to a detection signal of the reception pulse signal is transmitted, the transmission amplifier (350) amplifies a reradiation pulse generated in response to a detection signal of the pulse signal transmitted from the base station (200); and a re-reradiation pulse generated in response to a detection signal of the reradiation pulse.

Abstract: Provided is an array signal processing device capable of, when a spatial averaging method is applied to array signal processing, reducing the number of antennas constituting an array antenna while making use of the spatial averaging method. In the array signal processing device (300), an array antenna (310) comprises four antennas (311-1 to 311-4) disposed at the four vertices of a parallelogram. Correlation calculation units (341-1, 2) calculate, based on a received signal, spatial correlation matrices for respective sub-array antenna (312-1) and sub-array antenna (312-2), the sub-array antenna (312-1) comprising the antennas (311-1, 3) disposed at the opposing two vertices and the antenna (311-2), the sub-array antenna (312-2) comprising the antennas (311-1, 3) and the antenna (311-4). An array rotation unit (342) converts a first spatial matrix of the calculated two spatial matrices to the complex conjugate thereof.

Abstract: A positioning system and a positioning method which suppress the occurrence of jitter to improve positioning accuracy. A base station (100) of a positioning system (10) which comprises the base station (100) and a radio terminal (200), and measures the position of the radio terminal (200) to be positioned using a pulse signal, wherein a pulse generating block (103) transmits a pulse signal sequence, and an ID positioning block (110) calculates the time required for reciprocation between the transmission timing of the pulse signal sequence and the reception timing of a response pulse signal sequence transmitted from the radio terminal (200) which has received the pulse signal sequence, and calculates the position of the radio terminal (200) on the basis of the time required for reciprocation. Then, in the radio terminal (200) an LNA (203) amplifies the received pulse signal sequence and transmits the amplified pulse signal sequence to the base station (100) as a response pulse signal.