## 3 Major Applications of the Smart Grid Served by 6G
### Massive Connectivity and Monitoring  
The technology of 6G wireless communication is a feasible solution for massive connectivity and the time-critical monitoring of smart grid systems. Furthermore, 6G can provide seamless communication among a massive number of devices, thereby facilitating  
Figure 4: Flowchart of a 6G-Enabled Smart Grid.  
real-time data exchange, comprehensive time-critical monitoring, and effective energy management. For time-critical monitoring, along with massive connectivity, the important KPIs are connection density, area traffic capacity, data rate, reliability, latency, energy efficiency, and spectral efficiency. PD-NOMA offers notable performance and advantages that facilitate enhanced data rates, spectral efficiency, massive connectivity, as well as low latencies to support massive connectivity along with the time-critical monitoring of smart grid systems [104]. In PD-NOMA, distinct transmission powers are assigned to multiple users according to their respective channel conditions. The superimposed signal, containing data for all users, is then transmitted to them [105]. Based on the reception and channel condition, the users employ SIC or direct decoding to decode their respective signal. The SIC decodes the signal of individual users sequentially from the superimposed signal based on their assigned power [106]. Therefore, PD-NOMA, along with OAM-MIMO (NOMA-OAM-MIMO), can provide massive connectivity, high data rates, and improved spectral efficiency. Moreover, IRS, THz, and BF can be incorporated with the D2D/cooperative relay-based NOMA-OAM-MIMO communication for smart grid UDNs to provide improved reliability, low latency, less power consumption, enhanced area capacity, and an enhanced coverage area of the UDNs of a smart grid [81; 83; 84; 90; 91; 93; 95; 96; 97; 98; 99; 101]. Furthermore, NOMA-enabled Q-learning UDNs can also provide high area capacities and massive connectivity for the UDNs of a smart grid system [94; 107]. In addition, energizing the massive number of connected devices is another challenging issue. Thus, NOMA-incorporated wireless power transfers, such as NOMA-SWIPT, are required. They are needed to energize the IoTs, UAVs, robots, and edge/cloud devices, as well as provide energy efficiency [14].  
The grid monitoring algorithms (e.g., PLeC/AB-PLeC/FIB/BW-PLeC) can be processed by AI-based edge/cloud computing devices 8. The energy devices (e.g., IoTs, UAVs, and robots) can communicate with the edge/cloud devices via the abovementioned novel techniques of 6G wireless communication system for time-critical smart grid monitoring [108; 109]. The fault identification/location, as well as the deployment of the phasor measurement unit (PMU), are vital factors for grid monitoring [108]. For medium voltage grids, along with low latency monitoring, three different algorithms (path length constraint (PLeC), the application-level betweenness, along with PLeC (AB-PLeC), as well as the flow interference and bandwidth constraint (FIB)) were proposed in [108]. These algorithms are mainly focused on the strategic deployment of high-capacity links, thus aiming to strike a trade-off between deployment expenses and the achieved latency. The PLeC along with bandwidth and path length constraint (BW-PLeC) algorithms are introduced to achieve a low-latency communication framework [109]. These algorithms aim to enhance the performance of the conventional power-line communication technique by incorporating alternative enhanced speed communication links at crucial locations of the smart grid. The primary goal is to meet the specific delay requirements while minimizing deployment costs. All the requirements of the monitoring algorithms can be fulfilled by the abovementioned novel communication techniques of 6G.