Previously, we developed an embodied virtual communication system for human interaction analysis by synthesis in avatar-mediated communication and confirmed that the speech-overlap between talkers is closely related with the period in which embodied interaction and communication is activated through their avatars. In this paper, we propose an interaction-activated communication model based on the heat conduction equation for enhancing embodied interaction in avatar-mediated communication. Further, we perform the evaluation experiment and demonstrate that the proposed model is effective for estimating the period of interaction-activated communication in avatar-mediated communication.