## 5 CRS Distribution and Computations
Moreover, upon completing the ranking process, the \(rank\_1\) node advertises itself as the CH to all other nodes in the cluster through broadcasting. Now, the BS allows transmission slots based on the DD-TDMA scheduling scheme. The allotment completely depends on Minkowski distance, ranking, and type of services. It is a specialized version of both Manhattan and Euclidean distances, and its formulation is depicted in Equation (8). The nodes from different coverage ranges are identified through Minkowski distance. Two or more nodes are allocated with the same slots if their transmission radius is less than the Minkowski distance. Figures 4 shows the Service-oriented clustering in a smart city and Figures 5 shows Inter-clustering slot configuration. \[R_{i_{T_{x}}}[Rad]<\sum_{k=1}^{n}\left[|R_{i}^{S}-R_{i}^{D}|R_{i}^{S}|^{S}_{i} \right]^{\frac{1}{R_{i}^{S}}} \tag{8}\]  
DD-TDMA [42] is an enhanced TDMA scheduler that relies on the local neighborhood data to arrange slots to prevent collisions. Here, if multiple nodes are in differing coverage regions, they may also broadcast in the same slot. Thus, it optimizes the load balance through the network. The entire communication is categorized into two levels: homogeneous and heterogeneous. All the homogeneous communications are done at the intra-cluster level, whereas the heterogeneous communications are handled through the inter-cluster level where various types of nodes communicate. The maximum of single-hop communication is fixed for intra-cluster transmission until the data packet does not exceed the predefined slot period. The first slot of each transmission frame is open to all the deployed nodes to gain network knowledge, including BS and the nearest deployed node (ID, energy status, positional coordinates, and service type). Subsequently, different sets of ranking nodes are allocated to different slots. Finally, the intermediate slots between ranking nodes' slots are assigned to a CH to manage load distribution and ensure the reliability of any broadcast transmissions. The heterogeneous communication is carried among different service-based CHs. Similar to the communication procedures of the intra-cluster level, the \(slot\_0\) is made open to all the CHs to gain knowledge on the deployed network (such as nearest CH, BS position, and energy status of nearby CHs). Different sets of CHs are allocated to different slots. The intermediate slots between allotted slots of CHs are assigned to the BS to manage load distribution and ensure the reliability of any broadcast transmissions. The reactive and proactive routing procedures begin at intra-level and inter-level clustering once the BS sends updated routing information throughout the smart city environment. Whenever the particular nodes' transmission exceeds the predefined time slot, it can route the excess data packets through known 1-hop or 2- hop communicative nodes. Similarly, with the CH, the aggregated sensor data are routed during their allotted time slots, and if the transmission process exceeds the time limit, the excess packets are routed through the nearby CH identified at \(slot\_0\) session. The three intra-cluster routing strategies cases are depicted in Figures 6 to 11. Figure 4: Service-oriented clustering in a smart city. Figure 5: Inter-clustering slot configuration. All the CHn transmission slots are allocated with its R1 node to route the data packets whenever the particular CH fails during the transmission due to potential faults. Thus, this procedure ensures complete and reliable data transmission. The selection of intermediate nodes to route the excess data packets is processed through Minkowski computations and residual energy. Figure 8: \(Case_{1}\) of intra-cluster routing. Figure 6: Transmission frame of intra-cluster slot allocations. Figure 7: Transmission frame of inter-cluster slot allocations. Figure 9: \(Case_{2}\) of intra-cluster routing.