Abstract. Transaction Level Modeling (TLM) is seen as an efficientEmbedded System modeling technique to reduce the simulation time in large and complex designs. This is achieved by abstracting away pin-and cycle-accurate details from communication transactions, which reduces the number of events that need to be simulated.In this paper, we apply TLM principles to communication modeling in Wireless Sensor Networks (WSN). Modeling and simulating wireless communication is critical in exploration and optimization of WSNs as it enables evaluation of system design choices early in the design process.Unlike on-chip bus modeling, wireless communication modeling is broadcast-based and unreliable, which requires distributed medium access arbitration and timeout/retransmission capabilities. We present two TLMs of TDMA and CSMA/CA protocols. Our models are scalable to large networks and flexible in parameters and protocol configuration. Our experiments demonstrate insights to how adjusting protocol parameters in various network configurations affects the overall WSN performance.