Patent ID: 7363007

Claim:
A communication method in a radio communication system including a transmission device and a reception device, comprising the steps of: in the transmission device: estimating a first propagation condition regarding a propagation channel between the transmission device and the reception device, setting a multi-level modulation index m according to an estimation result of the first propagation condition, coding a transmission signal, multi-level-modulating the coded transmission signal with the multi-level modulation index m, and transmitting the modulated, coded transmission signal; and in the reception device: estimating a second propagation condition regarding the propagation channel between the reception device and the transmission device, setting a multi-level demodulation index n according to an estimation result of the second propagation condition, wherein n is different from the multi-level modulation index m that is used in transmission, receiving the signal transmitted from the transmission device, demodulating the reception signal received according to the second propagation condition with the multi-level demodulation index n, and decoding the demodulated reception signal.