Bluetooth Low Energy (BLE) is a short range, low power wireless networking technology that is increasingly used in various applications of the Internet of Things (IoT). The goals of this book is to design, implement, and evaluate simulation models for BLE focusing on multi device environments. Relevant performance metrics include the delay and energy consumption. Suitable abstraction of the different protocol layers has been defined to allow for implementing relevant aspects for the simulator. The simulation results are compared with real world hardware to measure the difference and to find the reasons for the differences.