4 [25 marks] Figure 5 illustrates an IoT-based perimeter intrusion detection system for railway applications. Application Layer Network Layer Perception Layer Perimeter intrusion type Wired network Perimeter intrusion position intrusion object Fiber optics vibrations Perimeter Data-Fusion Algorithms Internet LAN/Private wired network Video surveillance Sensor Network Perimeter intrusion track Wireless network 4G/WLAN/WIMAX Unmanned aerial vehicle Figure 5: IoT-based perimeter intrusion detection system for railway applications