An access point (AP) transmits Wi-Fi transmit frames according to a Wi-Fi protocol and Long-Term Evolution-Unlicensed (LTE-U) transmit frames according to an LTE-U protocol in a shared channel bandwidth that encompasses unlicensed channel bandwidth associated with the LTE-U protocol. The AP assigns a Wi-Fi access category to each Wi-Fi transmit frame and assigns to each LTE-U transmit frame an LTE-U access category. The AP schedules Wi-Fi and LTE-U transmit opportunities for the Wi-Fi transmit frames and the LTE-U transmit frames, respectively, in the shared channel bandwidth based on the Wi-Fi and LTE-U access categories. The scheduling includes, for each scheduled LTE-U transmit opportunity: constructing a Wi-Fi quiet message commanding Wi-Fi clients of the AP not to transmit in the shared channel bandwidth during the LTE-U transmit opportunity; and scheduling the Wi-Fi quiet message for transmission to the Wi-Fi clients.