## 5 Network Performance Parameters  
In this section, we present and define nine performance parameters that are used in this paper to comprehensively evaluate and compare the effectiveness of the proposed EEUCH protocol against existing benchmark routing protocols. These performance parameters are carefully selected to assess various aspects of the proposed protocol's performance and facilitate informed comparisons with existing benchmark routing protocols. 1. Number of alive SNs: This parameter represents the number of SNs having residual energy (\(E_{r}\)) greater than zero, known as alive SNs, as the rounds pass. Every single data packet transmission consumes a unit energy, and as several data packets are transmitted in a single round from SN to UAV, the SN energy is reduced from initial energy to zero as the rounds pass. This parameter provides an important metric of how many SNs are still operational at a particular round of the protocol. The higher the number of alive SNs, the better the protocol's efficiency in energy conservation, prolonging the network lifetime. 2. Number of dead SNs: This parameter indicates the number of SNs whose residual energy drops to zero during the rounds of the protocol. As each data packet transmission consumes a unit of energy, the SNs gradually consume their initial energy and eventually become unable to transmit data. This parameter indicates the number of SNs that have failed and cannot participate in subsequent rounds. 3. Total number of packets collected from FoI: This parameter determines the total number of data packets collected from the FoI over the course of the network's lifetime. This metric demonstrates the overall effectiveness of the protocol in gathering data. A more efficient protocol should be able to collect a larger number of data packets while extending the network lifetime. 4. Remaining network energy over the rounds: This parameter quantifies the amount of network energy that remains as the rounds pass. It reflects the overall network sustainability, which is vital for the longevity of the network lifetime. It is calculated by subtracting the total energy consumed till the current round from the initial network energy. A more efficient protocol should achieve a longer network lifetime by minimizing the rate at which energy is consumed. The total network initial energy is different for homogeneous, two-tier, and three-tier heterogeneous WSNs. For a homogeneous network, initial energy can be calculated using (4) below for which LEACH, LEACH-C, TEEN, IEE-LEACH, and the proposed EEUCH routing protocols are employed, while for two-tier and three-tier heterogeneous networks, we  
Figure 5: Illustration of the data flow for EEUCH. where \(E_{c}^{R}\) is the energy consumed in a single round, \(E_{TX}\) is given in Equation (2), \(N_{alive}\) is the total number of alive SNs in the particular round, \(CH_{nodes}\) CH nodes selected from \(N_{alive}\), and \(E_{DA}\) is data aggregation energy consumed by CH node. 7. Network lifetime: This is the time from the start till all the SNs die. More precisely, it is the time taken from the start (i.e., WSN or SNs deployment) till the last SN's death. Thus, \[T_{N}=(t_{r})\times(ASD)-(T_{START}),\] (9) where \(T_{N}\) is network lifetime, \(t_{r}\) is the time in which the data transmission occurs in each round, \(``ASD\"\) is the number of rounds when all SNs die, and \(T_{START}\) is the time when the WSN starts operating. 8. Stability time: It refers to the duration of time from the start of the network operation until the first SN in the network dies due to energy depletion. Stability time is an important metric to consider because it gives an indication of the overall network stability and robustness. A longer stability time means that the network is able to sustain its operation for a longer period without any significant disruptions or failures. This is particularly important for applications where the WSN is deployed in remote or inaccessible locations, and maintenance or repair may not be feasible or cost-effective.