Simulators are tools for understanding systems and predicting their behavior. They are supposed to be effective, efficient and to trade-off between the level of analytical detail, required to prevent misleading results, and simplicity, meant to keep computational load light. It is fundamental to evaluate the impact of any proposed improvement on the final results when enhancing the simulators. In accordance to these guidelines, this work proposes a novel WiFi physical model which is meant to be an enhancement of network simulators. An analytical model is proposed to adhere more closely to experimental benchmarks on Packet Error Rate (PER) vs Signal-to-Noise Ratio (SNR) for different packet lengths. Network simulations assess the relevance of the proposed model.