Wireless NoC (WiNoC) has low latency and simple wiring, which can reduce the energy consumption caused by the metal interconnection in traditional NoC architectures. However, traditional time division based media access control (MAC) mechanism in WiNoC is not aware of different wireless interfaces' (WIs) traffic demands, resulting in an unreasonable distribution of wireless communication channels and degradation in performance. Hence, in order to dynamically allocate wireless channels to the WIs based on their traffic demands, a dynamic and traffic-aware MAC mechanism is required. In this paper, we design a traffic demand predictor for each WI based on its current and history traffic conditions. According to the predicted demands, we are able to allocate access to wireless channels dynamically and switch between two kinds of time division based MAC mechanisms. Simulations under various conditions indicate that the average delay decreases by 30% and 20% on average compared with a traditional MAC mechanism and an existing dynamic time division based one, respectively. Moreover, the network with the dynamic and traffic-aware MAC enters the saturation point at a higher packet injection rate.