Communication apparatus and communication method

A communication apparatus comprising:

• a receiver which, in operation, receives a PHY layer Data Unit that includes a duration field, the duration field including duration information that indicates a duration of time during which the communication apparatus is prohibited from transmitting a high efficiency (HE) trigger-based (TB) PHY layer Data Unit;
• and
• Physical (PHY) layer circuitry which, in operation, issues a PHY-CCA (clear channel assessment) primitive parameter indicating bandwidth information on a busy or idle state for each subchannel within an operating bandwidth;
• and
• Media Access Control (MAC) circuitry which, in operation, updates a Network Allocation Vector (NAV) value based on the duration information when the indicated duration is greater than a current NAV value and when it is determined that the communication apparatus is not a targeted recipient of the received PHY layer Data Unit;
• and, in operation, determines busy/idle state of at least one subchannel that includes an resource unit (RU) in which the HE TB PHY layer Data Unit is to be transmitted, based on the bandwidth information,
• wherein the MAC circuitry, in operation, controls transmission of the HE TB PHY layer Data Unit based on the updated NAV value and the busy/idle state of the at least one subchannel, and controls the PHY circuitry to have the HE TB PHY layer Data Unit transmitted when the at least one subchannel, which does not include a primary subchannel, is considered idle, regardless of whether the primary subchannel is busy or not.