A base-station apparatus (101) and a terminal apparatus (102) communicate with each other in a communication system. When reporting reception quality information together with data to the base-station apparatus via a channel for use in data transmission, the terminal apparatus reports the reception quality information using a spatial multiplexing method identical to a spatial multiplexing method of the data if the reception quality information is reception quality information that is to be nonoperiodically reported, and reports the reception quality information using a spatial multiplexing method independent of the spatial multiplexing method of the data if the reception quality information is reception quality information that is to be periodically reported. When extracting the reception quality information reported together with the data from the terminal apparatus, the base-station apparatus extracts the reception quality information based on the assumption that the spatial multiplexing method of the reception quality information is identical to the spatial multiplexing method of the data if the reception quality information is nonoperiodically reported, and extracts the reception quality information based on the assumption that the spatial multiplexing method of the reception quality information is independent of the spatial multiplexing method of the data if the reception quality information is periodically reported.