Patent ID: 8009611

Claim:
A radio apparatus for communicating with a plurality of terminal apparatuses by using a packet signal composed of at least one stream, the apparatus comprising: an assignment unit which divides a specified period into a plurality of partial periods and assigns corresponding partial periods respectively to the plurality of terminal apparatuses by associating those periods with the terminal apparatuses; a generation unit which generates a control packet signal containing information on the corresponding partial periods assigned to the plurality of respective terminal apparatuses by said assigning unit and which generates a check packet signal in which known signals are assigned to streams, respectively, the number of the streams to which the known signals are assigned being greater than the number of streams to which data signal is assigned; and a communication unit including: a transmitting means which transmits the check packet signal in a corresponding partial period assigned by said assignment unit, after the control packet signal generated by said generation unit has been transmitted; and a receiving means which receives packet signals containing check results from the plurality of respective terminal apparatuses, in the corresponding partial periods assigned by said assignment unit, wherein said generation unit generates the check packet signal for the plurality of respective terminal apparatuses, as a single packet signal.