Localization plays a substantial role in the future Internet, especially within the context of the Internet of Things (IoT). Increased dependence on devices and sensed data presses for more efficient and accurate localization schemes. In the IoT environment the area covered is large making it impossible to localize all devices and Sensor Nodes (SNs) using single-hop localization techniques. A solution to this problem is to use a multi-hop localization technique to estimate devices' positions. Simulating localization techniques for wireless sensor networks is required in order to reduce cost and study the difference between localization techniques easily especially if the simulated environment is large. Thus a realistic model is required to simulate the localization process as accurately as possible. Many multi-hop localization techniques use Received Signal Strength Indicator (RSSI) to estimate the distance between SNs. Our interest in this work is to enhance the validation of these schemes prior to deployment. Specifically, we propose the use of a more realistic model for generating RSSI values. The model is based on practical measurements and is validated through extensive simulation.