Abstract: A radio base station performs wireless communication with a wireless terminal. The radio base station includes a directivity pattern specifying unit, a communication unit, and a signal processor. The directivity pattern specifying unit specifies plural directivity patterns. The communication unit receives a search request frame from the wireless terminal, sends to the wireless terminal a search response frame which is a response to the search request frame, with at least one, specified by the directivity pattern specifying unit, of the directivity patterns, and receives a delivery acknowledgment frame for the search response frame from the wireless terminal with the directivity patterns specified by the directivity pattern specifying unit. The signal processor calculates, for each specified directivity pattern, a radio wave intensity of the delivery acknowledgment frame.

Abstract: According to an embodiment, a calculation method is for performing calculation on a wireless network including multiple terminals and multiple base stations. The method includes calculating a first probability with which a first base station and a second terminal are capable of connection with (h?1) hops, h being a finite integer equal to or larger than 2, and a first terminal and the second terminal are capable of direct connection with each other, by using a probability with which the first terminal and the second terminal are capable of direct connection with each other and a probability with which the second terminal and the first base station are capable of direct connection with each other; and calculating a second probability with which the first terminal is capable of connection with at least one of the base stations with h hops by using the first probability.

Abstract: According to an embodiment, a position calculation method includes obtaining a plurality of candidate positions each of which represents a position of a corresponding one of a plurality of base stations to be installed in a wireless network; calculating a condition of an optimization problem for deciding installation positions of base stations from the candidate positions by using probabilities of connection between a plurality of terminals included in the wireless network and the base stations installed at the candidate positions; and calculating the installation positions by solving the optimization problem under the condition.

Abstract: A communication device includes a signal processing device, a transceiver, and a controller. The signal processing device uses a first signal medium. The transceiver communicates with at least one of first devices by using a second signal medium. The controller controls usage of the first signal medium by the communication device and the at least one of first devices by communicating with the at least one of first devices by the transceiver.

Abstract: According to one embodiment, a monitoring apparatus includes a communication unit and a determination unit. The communication unit is configured to calculate a first indicator value and a second indicator value, the first indicator value relating to a received signal strength at a time when a packet transmitted from a first wireless device is received, the second indicator value relating to a received signal strength at a time when carrier sense is executed. The determination unit is configured to determine a state of the first wireless device to be one of three or more states, by performing a state determination using the first indicator value and the second indicator value, with a current state of the first wireless device being set as a basic point.

Abstract: A wireless communication device transmits data to a relay destination being one of first relaying devices capable of communicating out of relaying devices; obtains first information, from each first relaying device, that indicates a representative value of remaining operating times of relaying devices present on a relay route from the first relaying device to a target device; determines to perform a new route search, based on the first information; increases a transmission power; then transmits a request; receive responses from all or a part of second relaying devices, which are relaying devices that have received the request, including pieces of second information each of which indicates a representative value of remaining operating times of relaying devices present on a relay route from the second relaying device to the target device; and selects a relay destination of data from among the second relaying devices based on the pieces of second information.

Abstract: According to this embodiment, a position estimating device, that estimates a position of a target wireless device, includes a storage that stores positions of a plurality of reference wireless devices, a receiver which is notified of a received signal strength indicator value in signal transmission and reception between the target wireless device and each reference wireless device, a calculator that calculates a standard deviation for a probability distribution of a distance between the target wireless device and each reference wireless device, using the received signal strength indicator value, a first estimator that calculates an estimated distance between the target wireless device and each reference wireless device, using the received signal strength indicator value, and a second estimator that calculates the position of the target wireless device, using the standard deviation, the estimated distance, and the positions of the plurality of reference wireless devices.

Abstract: According to one embodiment, a failure detection apparatus includes a communicator, a selector, an execution unit, and a determiner. The communicator communicates with a wireless terminal mounted on a moving object via at least one of first bridge devices located at predetermined positions. The selector selects second bridge devices from the first bridge devices. The execution unit executes test connections to the wireless terminal using the second bridge devices. The determiner determines that the wireless terminal is inoperative if the test connection via any of the second bridge devices has failed.

Abstract: A wireless communication apparatus includes: a communication module configured to wirelessly communicate with first and second counterpart communication apparatuses through a wireless channel during a period in which the wireless channel is allowed to be exclusively used, wherein the communication module multiplexes first and second data frames and transmits the first and second data frames to the first and second counterpart communication apparatuses, wherein the communication module completes receiving first and second receipt confirmation frames being respectively sent from the first and second counterpart communication apparatuses at first and second receipt completion timings, the second receipt completion timing being in synchronization with the first receipt completion timing, and wherein the communication module transmits a next first data frame and a next second data frame after elapse of a given time from the first receipt completion timing and the second receipt completion timing.

Abstract: A wireless communication apparatus includes: a communication module configured to wirelessly communicate with first and second counterpart communication apparatuses through a wireless channel during a period in which the wireless channel is allowed to be exclusively used, wherein the communication module multiplexes first and second data frames and transmits the first and second data frames to the first and second counterpart communication apparatuses, wherein the communication module completes receiving first and second receipt confirmation frames being respectively sent from the first and second counterpart communication apparatuses at first and second receipt completion timings, the second receipt completion timing being in synchronization with the first receipt completion timing, and wherein the communication module transmits a next first data frame and a next second data frame after elapse of a given time from the first receipt completion timing and the second receipt completion timing.

Abstract: A communication device includes a receiver, a transmitter and an interruption module. The receiver receives an allocation signal indicating a first period usable by the communication device and a second period usable by a plurality of communication devices including the communication device. The transmitter transmits a transmission signal in the first period. If the transmission of the transmission signal is completed within the first period, the interruption module interrupts at least a part of power supply to the receiver in the second period. If the transmission of the transmission signal is not completed within the first period and directivity of radio waves used by a second communication device includes a direction of the communication device in a communication period allocated before the second period, the transmitter transmits the transmission signal in the second period.

Abstract: One of a plurality of radio terminals that transmit radio signals to a radio base station under a space multiplexing scheme, including a receiving unit that receives an access right request signal with respect to the radio base station from an other radio terminal, a prevention unit that prevents transmission of radio signals when receiving radio signals directed to an other radio terminal, a cancellation unit that cancels the prevention of transmission when receiving an access right assignment signal during the prevention of transmission and a transmitting unit that transmits a data signal to the radio base station according to the assignment signal, wherein radio signals are transmitted to the radio base station simultaneously with the other radio terminals and under the space multiplexing scheme.

Abstract: A communication device includes a receiver, a transmitter and an interruption module. The receiver receives an allocation signal indicating a first period usable by the communication device and a second period usable by a plurality of communication devices including the communication device. The transmitter transmits a transmission signal in the first period. If the transmission of the transmission signal is completed within the first period, the interruption module interrupts at least a part of power supply to the receiver in the second period. If the transmission of the transmission signal is not completed within the first period and directivity of radio waves used by a second communication device includes a direction of the communication device in a communication period allocated before the second period, the transmitter transmits the transmission signal in the second period.

Abstract: One of a plurality of radio terminals that transmit radio signals to a radio base station under a space multiplexing scheme, including a receiving unit 42 that receives an access right request signal with respect to the radio base station from an other radio terminal, a prevention unit 43 that prevents transmission of radio signals when receiving radio signals directed to an other radio terminal, a cancellation unit 43 that cancels the prevention of transmission when receiving an access right assignment signal during the prevention of transmission and a transmitting unit 41 that transmits a data signal to the radio base station according to the assignment signal, wherein radio signals are transmitted to the radio base station simultaneously with the other radio terminals and under the space multiplexing scheme.

Abstract: One of a plurality of radio terminals that transmit radio signals to a radio base station under a space multiplexing scheme, including a receiving unit 42 that receives an access right request signal with respect to the radio base station from an other radio terminal, a prevention unit 43 that prevents transmission of radio signals when receiving radio signals directed to an other radio terminal, a cancellation unit 43 that cancels the prevention of transmission when receiving an access right assignment signal during the prevention of transmission and a transmitting unit 41 that transmits a data signal to the radio base station according to the assignment signal, wherein radio signals are transmitted to the radio base station simultaneously with the other radio terminals and under the space multiplexing scheme.

Abstract: A wireless communication apparatus which can simultaneously conduct communication on at least two frequency channels is described. The apparatus includes a communication unit which refers to a connection management table to determine a communication system which can be used by a wireless communication terminal using an identifier of the wireless communication terminal, and conducts communication with the wireless communication terminal on a second frequency channel using the communication system, when a request from the wireless communication terminal to change the first frequency channel to the second frequency channel is permitted.

Abstract: A communication device includes a receiver, a transmitter and an interruption module. The receiver receives an allocation signal indicating a first period usable by the communication device and a second period usable by a plurality of communication devices including the communication device. The transmitter transmits a transmission signal in the first period. If the transmission of the transmission signal is completed within the first period, the interruption module interrupts at least a part of power supply to the receiver in the second period. If the transmission of the transmission signal is not completed within the first period and directivity of radio waves used by a second communication device includes a direction of the communication device in a communication period allocated before the second period, the transmitter transmits the transmission signal in the second period.

Abstract: According to one embodiment, a communication device includes a receiver, a transmitter and an interruption module. The receiver receives an allocation signal indicating a first period usable by the communication device and a second period usable by a plurality of communication devices including the communication device. The transmitter transmits a transmission signal in the first period. If the transmission of the transmission signal is completed within the first period, the interruption module interrupts at least a part of power supply to the receiver in the second period. If the transmission of the transmission signal is not completed within the first period and directivity of radio waves used by a second communication device includes a direction of the communication device in a communication period allocated before the second period, the transmitter transmits the transmission signal in the second period.

Abstract: According to one embodiment, a communication device includes a receiver, a transmitter and an interruption module. The receiver receives an allocation signal indicating a first period usable by the communication device and a second period usable by a plurality of communication devices including the communication device. The transmitter transmits a transmission signal in the first period. If the transmission of the transmission signal is completed within the first period, the interruption module interrupts at least a part of power supply to the receiver in the second period. If the transmission of the transmission signal is not completed within the first period and directivity of radio waves used by a second communication device includes a direction of the communication device in a communication period allocated before the second period, the transmitter transmits the transmission signal in the second period.

Abstract: A wireless communication system includes a first wireless communication apparatus and a second wireless communication apparatus which communicate with each other. The first wireless communication apparatus simultaneously transmitting frames to the second wireless communication apparatus through first to nth (n is an integer of 2 or greater) frequency channels, the second wireless communication apparatus receives the frames from the first wireless communication apparatus through the first to nth frequency channels, judges success or failure of reception of each of the frames by performing error detection, creates delivery confirmation frame including information indicating success or failure of reception of each of the frames, and transmits the delivery confirmation frame through x specific channel (x is an integer in a range from 1 or more to n?1 or fewer) of the first to nth frequency channels to the first wireless communication apparatus a predetermined time after reception of the frames.