IEEE 802.11bc is especially designed for enhancing the broadcast performance in wireless local network. Focusing on improving the broadcast data frame scheduling and origin authenticity performance, the broadcast data frame scheduling scheme is completely re-designed and the data origin authenticity is introduced in the IEEE 802.11bc. However, after introducing these updated mechanisms, the data broadcast performance due to station mobility, especially during the handover period, remains un-explored. Motivated by this, in this paper, we investigate the downlink handover broadcast data frame loss rate in the IEEE 802.11bc. With special focus on the updated broadcast data frame scheduling and data authentication in the IEEE 802.11bc, we derive an analytical model for the downlink broadcast frame loss rate. Based on the analytical model and simulation test, we give the broadcast parameters configuration for the specified average broadcast data frame loss rate constraint.