## 6 Simulation Results
It is due to the involvement of many nodes for single-packet delivery in the existing schemes, while in the CoSiM-RPO, at most two nodes are involved in data transmission, leading to less consumption of energy comparatively. ODBR has the lowest energy consumption with respect to DBR and CoDBR. ODBR balances the cost of energy by assigning energy in an organized manner based on data load on the nodes, while in DBR, all nodes have the same energy level. Therefore, ODBR's energy cost is lower than DBR and CoDBR, because CoDBR consumes a high amount of energy due to the greater number of nodes involve in data forwarding. CoDBR has the greatest energy consumption among the other algorithms. In CoDBR, the data are cooperatively forwarded to the destination. Almost one packet is delivered to the destination along three paths, and three nodes are involved in a single delivery. Due to the cooperation of the nodes, they consume the greatest energy, while in DBR and ODBR, the data are delivered over a single path through multiple hops to the sink and energy is consumed only by one node for a single-packet transmission to the next forwarder. Therefore, the energy consumed by DBR and ODBR is lower than CoDBR. The cost paid as consumed energy is summarized as SiM-RPO energy consumption < CoSiM-RPO < ODBR < DBR < CoDBR. The remaining energy is reciprocally related to the energy cost. Therefore, all the above discussion for the consumption of energy is conversely true for the residual energy and is shown in Figure 7.  
The CoSiM-RPO algorithm outperformed all the schemes in terms of packets reception, as shown in Figure 8. The CoSiM-RPO algorithm has the greatest packet reception. In the proposed algorithm, MSs move to establish a direct link between the node and themselves for data collection directly from the nodes without multiple hops, which enhances the chance of the packets' reception. Furthermore, the MS checks the data quality to receive accurate data. If the received data do not meet the specified  
Figure 6: Consumption of energy. criteria of correct reception, then a request for retransmission is sent, and the relay forwards the data again toward the MS. Thus, this results in more packets being received at the MSs. While in the SiM-RPO scheme, the data are delivered only in a single path to the MS having a greater chance of packets being dropped compared to the CoSiM-RPO, the packets' reception is the highest in CoSiM-RPO. In the other counterpart schemes, the data are delivered through multiple relays to the sinks. Therefore, there is a high probability of data destruction due to the channel effects, and the chance of the packets' reception is always lower than the proposed scheme. Furthermore, the network density is directly related to the packet reception. This is because, if the nodes died, then the path to the sink is broken, and all the packets is dropped. The SiM-RPO algorithm has the greatest packet reception compared to the counterpart schemes. This is because the packet is delivered directly to the MS without multiple hops. The direct transmission has less chances of data corruption instead of multiple hops due to the channel effects. While in the  
Figure 8: Received packets. Figure 7: Remaining energy. counterpart schemes, the data are delivered in a multi-hop fashion, the packets reception in the SiM-RPO algorithm is the highest among the counterpart schemes. While before 500 rounds, the SiM-RPO has lower packets reception than CoDBR, this is because the data reception probability is high due to cooperation in CoDBR. The packet reception of CoDBR is the greatest compared to DBR and ODBR. The CoDBR algorithm forwards data to the destination along three different paths to reduce the channel effects. Therefore, the chance of the packets' reception is higher in CoDBR than in DBR and ODBR, while in DBR and ODBR, a single path that may be noisy and have greater channel effects is followed toward the sink. More packets are received in ODBR than DBR.