1. A communication apparatus comprising:receiving means for receiving a signal transmitted from a base station constructing a wireless network conforming to IEEE802.11 series of standards, the signal including information on an AIFSN value, and
control means configured to, in a case where the AIFSN value included in the signal received by the receiving means is zero and upon successfully transmitting data of an access category in an accessed uplink OFDMA resource unit provided by the base station,
switch the access category from a legacy contention mode to an MU contention mode and prevent data of the access category from being transmitted to the wireless network;
wherein, in the MU contention mode, Enhanced Distributed Channel Access (EDCA) transmission of data of an access category is disabled.