Tomoya Horiguchi

TL;DR: In this article, a radio communication system which includes a base station and terminal apparatuses and performs TDD two-way communications using an OFDM signal including subcarriers in a downstream communication from the base station apparatus to each terminal apparatus, and an FH signal having the same frequency band as that of the subcarrier in an upstream communication from each terminal device to the BS, is described.

TL;DR: In this article, a cognitive radio system includes a state detecting device that scans a frequency band allocated to another radio system than the CR system to detect a first use state of the frequency band; a first server including a first gathering unit that receives first information relating to the first use-state and a second gathering unit; a second server that stores a second use-State of the spectrum allocated to the other radio system; and a notifying unit that notifies a CR system of information of an available channel based on the first information and the second information.

TL;DR: In this paper, a radio communication apparatus for receiving OFDM signal from base station and transmitting FH signal to base station, using sub-channels, including estimation unit configured to estimate channel response values of subchannels based on OFDM signals, selector which selects, from sub-Channels, several sub-channel which have higher channel response value than a value, each of channel responses being expressed by power level, signal to noise power ratio, or signal to interference ratio.

TL;DR: In this article, a cognitive communication system consisting of a medium estimator 104 provided in a radio terminal 1005 for detecting whether the radio channel allocated to the other radio equipment is in use or in a free state was proposed.

TL;DR: In this article, a communication apparatus includes unit measuring a first interference feature quantity indicating a state of an interference signal in a transmission frequency band (TFB), unit determining from the first feature quantity whether the interference signal exists in the TFB, unit acquiring, after measurement of the first interference measure quantity, a transmission channel from a second interference measure, measured by the measuring unit, the transmission channel corresponding to at least one of a frequency orthogonal to the interference signals, a time orthogonality, and a spreading code, and unit performing a first transmission using the TF