# Key Technologies for 6G-Enabled Smart Sustainable City
## 4 Key Candidate Technologies for Future SSC
### Prime Technologies for SSC
#### 4.2.5 Integrated Sensing and Communication
In the following, we discuss the potential benefits of ISAC when applying ISAC in SSC. * _Ultra-wideband communication_: Millimeter wave is considered a key technology for future 6G networks. ISAC systems are particularly suited to high-resolution sensing tasks when operating in the millimeter wave band. This can be utilized effectively in 3D imaging and applications with millimeter-level resolution. mmWave can be used to help autonomous vehicles accurately sense and react to their surroundings, while 3D imaging allows vehicles to understand obstacles around them or interactions with other vehicles in real-time. It is also expected to be utilized in security systems and medical applications [52]. * _High accuracy and localization_: In future super-intelligent societies, location determination methods, such as collaborative mapping techniques, play a crucial role in training robots to emulate human-like senses. ISAC enables the localization and tracking of various objects such as vehicles and drones. High-precision relative localization becomes crucial when two or more entities approach each other or move cooperatively. The  
Figure 6: Application of ISAC on 6G-enabled SSC use cases. advanced accuracy and localization capabilities of ISAC can contribute to innovation in autonomous technologies such as robots and drones [53]. * _Gesture and activity recognition_: Human gestures play a crucial role as an interface for interacting with IoT and mobile devices. The ISAC networks, utilizing a broad bandwidth, offer enhanced resolution and accuracy in capturing gestures, thereby enabling a diverse range of applications that leverage gesture-capturing techniques. Furthermore, the ISAC-based technology for gesture and activity recognition is well suited for smart city scenarios, especially in minimizing the exposure of personal information when compared to camera-based activity recognition technology. For example, smart hospitals may incorporate functions such as intrusion detection or respiratory sensing without relying on camera devices [115]. * _Augmented human senses_: The ISAC system is recognized as a leading candidate for driving innovation in SSC, attributed to its capability to recognize surrounding environments beyond human capabilities. The augmented sensing technology utilizes portable devices to sense the surrounding environment, emphasizing the integration of high-resolution imaging and communication capabilities to intelligently manage the SSC infrastructure. For example, augmented human sensing functions in ISAC systems could enhance key SSC functions, including environmental monitoring, traffic flow management, and the reinforcement of safety and security [52; 54]. ISAC can be verified in real-world environments. Taking environmental monitoring as an example, it performs sensing by analyzing the path loss of mmWave links and observing changes in environmental characteristics such as moisture and insects. Cell networks with such sensing capabilities utilize communication systems to transmit collected data or receive commands. They contribute to the management and improvement of smart city infrastructure by detecting environmental factors like air pollution, noise levels, and temperature. Additionally, ISAC technology, applied to inter-vehicle communication within the city, concurrently achieves high-speed communication and precise vehicle localization. This enhances key functions such as secure access, simultaneous localization, and mapping, thereby elevating the efficiency and safety of smart city operations [116; 117].