A transmitting multi-link device (MLD) includes circuitry and a transmitter. The circuitry, in operation, constructs an Additional Authentication Data (AAD) and a Nonce, and encapsulates a plaintext medium access control (MAC) protocol data unit (MPDU), the AAD, and the Nonce to generate an encapsulated MPDU. The AAD includes an Address 1 (A1) field, to which a recipient MLD's MAC address is set, and an AAD Address 2 (A2) field, to which the transmitting MLD's MAC address is set. The Nonce includes a Nonce Address 2 (A2) field, to which the transmitting MLD's MAC address is set. The transmitter, in operation, transmits the encapsulated MPDU to the recipient MLD on a first link.