Using OPNET simulation we evaluate performance of interference mitigation of wireless local area network (WLAN) systems by means of message exchange based approaches when basic service sets (BSSs) of WLAN systems are overlapped. To do that, we consider 802.11af systems that utilize registered location secure server (RLSS). RLSS provides channel schedule management (CSM) that enables 802.11af access points (APs) to schedule operating channel use in order to mitigate OBSS interference. We also consider 802.11af systems that take advantage of knowledge of neighbor discovery and radio environment information provided by 802.19.1 system, called 802.19.1 coexistence information service. In case of 802.11af system without 802.19.1 system, performance of OBSS interference mitigation is heavily affected by each OBSS AP's radio environments based on awareness of co-channel sharing situation with harmful interference that initiates CSM. It is demonstrated that 802.19.1 coexistence information service enables 802.11af APs to facilitate the channel with negligible harmful OBSS interference.