Wireless communication system, wireless communication method, and transmitting device

[Problem]Conventionally, in a wireless communication system that performs single-carrier communication with formation of symbol blocks, it has been difficult to select the optimal GI length and modulation and coding method that achieve the maximum throughput.[Means of Solution]A transmission device and a reception device are included. The transmission device includes: a transmission-side communication unit that performs communication using a single or a plurality of antennas; a modulation unit that generates a single-carrier signal in which a symbol block has been formed; a GI insertion unit; a weight multiplication unit that performs multiplication by a weighting coefficient; and a control unit that obtains information of an impulse response of a communication path from the reception device by transmitting a training signal before starting communication, calculates the weighting coefficient, and determines a modulation and coding method and a length of a GI that achieve the maximum throughput in accordance with SINRs in a specific period that are calculated by changing a length of the GI. The reception device includes an estimation unit that estimates the impulse response of the communication path using a training signal transmitted from the transmission device, and notifies the transmission device of information of the estimated impulse response of the communication path.