Radio communication system and transmission mode selecting method

A radio communication system comprising first and second radio communication apparatuses which can communicate with each other by radio,

• wherein said first radio communication apparatus comprises:
• a propagation path environment estimator which outputs, as propagation path environment information, a result of estimation of an environment of a propagation path to said second radio communication apparatus on the basis of a signal from said second radio communication apparatus;
• a propagation path quality estimator which outputs, as propagation path quality information, a result of estimation of quality of the propagation path to said second radio communication apparatus on the basis of the signal from said second radio communication apparatus;
• an error detector which detects an error in the signal from said second radio communication apparatus and outputs the error as an error detection result;
• and
• transmitting means for transmitting the propagation path environment information, propagation path quality information, and error detection result together with a data signal to said second radio communication apparatus,
• wherein said second radio communication apparatus comprises:
• a transmission mode selector which includes a plurality of tables in which a plurality of transmission modes each having a threshold value corresponding to a value of the propagation path quality information are registered, selects one of said plurality of tables in accordance with the propagation path environment information, and selects, as a mode for transmission to said first radio communication apparatus, one of the transmission modes registered in the selected table in accordance with the propagation path quality information,
• wherein said transmission mode selector of said second radio communication apparatus rewrites, in accordance with the error detection result, a threshold value registered in the table to correspond to the selected transmission mode.