Recently, wearable devices have been attracting attention, which can easily measure an individual's health status, process the measurement data in an integrated manner, and provide meaningful feedback to the user. One of technologies supporting the development of the medical and healthcare IoT system is the WBAN. In particular, the SmartBAN is attracting attention. Existing studies on SmartBAN have focused on reducing uplink latency and energy consumption. On the other hand, there have been few studies on downlink applications of SmartBAN, such as XR and medical actuator control. This research proposes two schemes for effective downlink transmission within an SAP in the MAC superframe of the SmartBAN. Numerical results from computer simulation show that the proposed scheme dividing SAP into sections for uplink transmission and downlink transmission is more suitable for downlink transmission than the existing SmartBAN technical specifications.