Mobile Adhoc Networks (MANET) within the Internet of Things (IoT) framework is one of the most important wireless networks in which mobile nodes are interconnected and transmit packets in a distributed way to provide various IoT oriented services. The heterogeneity characteristic feature of IoT poses technical challenges on the MAC layer such as the increasing network traffic load, heterogeneous Quality of Service(QoS) demands. To overcome these problems, a superframe structure is designed that helps to prioritize voice and data packets and that helps to improve the performance in MANET. Within each superframe, voice packets access the channel in a contention-free period (CFP) for its transmission and data packets content for channel access in a contention period (cp). so, the maximal QoS performance is achieved by adapting to the network traffic load variations and that supports the heterogeneous QoS demands. In addition to the large coverage area, the multihop connection is enabled that helps to reduce the energy consumption of the nodes