Abstract: A passive intermodulation (PIM) canceller of a communication device includes a combining unit, a replica generating unit, and a delay measuring instrument. The replica generating unit generates an intermodulation signal based on the amount of delay of each transmission signal. The combining unit cancels out the intermodulation signal from the reception signal using the generated intermodulation signal. The delay measuring instrument delays a transmission signal x2 included in a plurality of transmission signals by different first amounts of delay. The delay measuring instrument generates an intermediate signal Sm1 by multiplying the delayed transmission signal x2 to the reception signal. The delay measuring instrument calculates, based on the correlation values of the intermediate signal Sm1 corresponding to each first amount of delay and a transmission signal x1 included in the plurality of transmission signals, the amount of delay of the transmission signal x1 with respect to the intermodulation signal.

Abstract: A node apparatus calculates the arrival rate in a link, discretizes the calculated arrival rate according to thresholds that are set so that the intervals between thresholds in the range in which a large number of the arrival rates in the links with a high frequency of usage exist become narrower, and calculates the link cost according to the value after the discretization. The node apparatus then obtains, from adjacent node apparatuses, the route cost for each route to each final destination that may be reached, and integrates the obtained route cost by the calculated link cost to calculate the route cost to each final destination that can be reached from the local node apparatus via the adjacent node apparatus. The node apparatus then selects the adjacent node apparatus to be the transmission destination according to the route cost of the route to the final destination of a data frame.

Abstract: A distortion cancel device includes: a first acquiring unit that acquires a plurality of transmission signals including at least two transmission signals that are wirelessly transmitted at an identical frequency; a second acquiring unit that acquires a reception signal to which an intermodulation signal generated due to the transmission signals is attached; and a processor that executes a process including: determining a ratio of the transmission signals acquired by the first acquiring unit and wirelessly transmitted at the identical frequency; generating a ratio signal for each frequency from the transmission signals in accordance with the determined ratio; generating a cancel signal corresponding to the intermodulation signal by using an arithmetic expression that uses the generated ratio signal; and combining the generated cancel signal with the reception signal acquired by the second acquiring unit.

Abstract: A delay measuring instrument includes a generating unit and a calculating unit. The generating unit is, for example, a multiplier. The calculating unit is, for example, a maximum value detecting unit. The generating unit generates an intermediate signal by multiplying one of transmission signals or the complex conjugate of the one of the transmission signals included in the plurality of transmission signals that are transmitted at different frequencies by a reception signal that includes therein an intermodulation signal generated by the plurality of the transmission signals. The calculating unit calculates, based on a correlation value between the intermediate signal and the other one of the transmission signals included in the plurality of the transmission signals, an amount of delay of the other one of the transmission signals with respect to the intermodulation signal.

Abstract: A distortion cancellation device includes a first acquiring unit that acquires a plurality of transmission signals that are wirelessly transmitted at different frequencies; a second acquiring unit that acquires a reception signal to which an intermodulation signal generated due to the plurality of the transmission signals is added; and a processor that executes a process including acquiring a gain difference between the plurality of the transmission signals generated when the plurality of the transmission signals acquired by the first acquiring unit is sent to a generation source of the intermodulation signal, generating, by an arithmetic expression using both the acquired gain difference and the plurality of the transmission signals, a cancellation signal associated with the intermodulation signal, and combining the generated cancellation signal with the reception signal acquired by the second acquiring unit.

Abstract: Node device calculates reception rate of frames of particular frame type transmitted from adjacent node device, calculates arrival rate of unicast frames on the basis of calculated reception rate and frame length, and calculates inverse number of calculated arrival rate as link cost. Node device obtains from adjacent node device route cost for each route from adjacent node device to each node device that is reachable final destination, calculates route cost of route from node device itself to each node device that is final destination reachable via adjacent node device by integrating calculated link cost and obtained route cost. Node device selects adjacent node device that is transmission destination of data frame on the basis of route cost of route from node device itself to node device that is final destination of data frame when data frame is transmitted.

Abstract: A node apparatus calculates the arrival rate in a link, discretizes the calculated arrival rate according to thresholds that are set so that the intervals between thresholds in the range in which a large number of the arrival rates in the links with a high frequency of usage exist become narrower, and calculates the link cost according to the value after the discretization. The node apparatus then obtains, from adjacent node apparatuses, the route cost for each route to each final destination that may be reached, and integrates the obtained route cost by the calculated link cost to calculate the route cost to each final destination that can be reached from the local node apparatus via the adjacent node apparatus. The node apparatus then selects the adjacent node apparatus to be the transmission destination according to the route cost of the route to the final destination of a data frame.

Abstract: Node device calculates reception rate of frames of particular frame type transmitted from adjacent node device, calculates arrival rate of unicast frames on the basis of calculated reception rate and frame length, and calculates inverse number of calculated arrival rate as link cost. Node device obtains from adjacent node device route cost for each route from adjacent node device to each node device that is reachable final destination, calculates route cost of route from node device itself to each node device that is final destination reachable via adjacent node device by integrating calculated link cost and obtained route cost. Node device selects adjacent node device that is transmission destination of data frame on the basis of route cost of route from node device itself to node device that is final destination of data frame when data frame is transmitted.

Abstract: A cognitive radio system includes cognitive radio apparatuses and a management server via a network. The cognitive radio apparatus includes a terminal communication part selecting a communication protocol, a communication quality acquisition part acquiring a communication quality including a current location of the selected protocol, and a communication quality notification part notifying the server of the information. The server includes a server communication part communicating with the apparatus, a communication quality collecting part collecting the information, a communication quality managing part recording and managing the information, and an area communication condition providing part providing the information to the apparatus.