Wireless sensor networks (WSNs) support real-time communication in various criticalapplications such as disaster alerts, health monitoring, and industrial automation, amongothers. In such systems, the data have to reach the monitoring stations before the expira-tion of deadlines. Therefore, to guarantee deadlines TDMA MAC schemes for real-timeow can be considered with both node interference and ow deadlines. But these sys-tems required much time complexity as the number of nodes or real-time ows increases.To solve this problem, however cluster-based TDMA scheduling schemes provide goodscalability and suitability for real-time communications. But in these schemes due tostatic scheduling and inter-cluster interference some real-time ows cannot be scheduledin available slots.iiiTo address mentioned issues this thesis presents ecient scheduling and synchro-nization schemes that precisely utilize the available slots. For the former issue two cluster-based scheduling schemes are introduced for real-time ows. One is hybrid schedulingfor clusters having either inside or outside ows can utilize both their intra-cluster time-slots, while the other adaptively utilizes the intra-cluster time-slots according to thestates of the ows. For the latter issue a token-based synchronization scheme is pro-posed, which provides token-based slot assignment starting from the high priority owsin the neighbor clusters. The token containing the slot number of higher priority owthen send to next priority ow in the neighbor clusters. Which schedules their transmis-sion in the same slot if not interfere with higher priority ows otherwise schedule in thenext available slot.The performance of proposed scheme have been evaluated by simulation in an exten-sive range of scenarios and compared to existing algorithms. We show the eectivenessof the proposed scheme in many aspects and compare that our scheme have more owsadmitted and delivered than existing solutions.