# An Improved Energy-Efficient Routing Protocol for Wireless Sensor Networks
## 3 Proposed Scheme
### Improved Energy-Efficient LEACH Protocol
#### 3.2.4 Data Transmission Scheme of the IEE-LEACH Protocol  
To decrease energy consumption, the radio network of the CH and nodes is closed until the transmission slot is assigned. The radio network of the CH and nodes that intend to send the data need to be activated. After activating the nodes, non-CH nodes send the data to the CH, while the CH receives these data and sends them to the BS [34; 35]. A single data communication approach will increase the energy consumption of the nodes because the best way to transfer data are to minimize the distance between nodes. Therefore, we propose a methodology that provides a single hop, multi-hop and hybrid communication network to minimize the distance. It is assumed that the cluster head node transmits data to BS by \((n-1)\) hops and the distance of each hop is \(r\) in the wireless sensor network with the free-space channel model. Therefore, to transmit an \(m\)-bit message, the energy consumption for signal hop is given by  
Figure 4: Cluster formation. Figure 5: Block diagram of proposed protocol. \[E_{1} = E_{TX}\left(m,n\times r\right) \tag{20}\] \[= m\times E_{elec}+m\times\varepsilon_{fs}\times\left(nr\right)^{2}\] \[= m\times\left(E_{elec}+\varepsilon_{fs}\times n^{2}\times r^{2} \right).\]  
The energy consumption for multi-hop can be expressed as  
\[E_{2} = n\times E_{TX}\left(m,r\right)+\left(n-1\right)\times E_{RX} \left(m\right) \tag{21}\] \[= n\times m\times\left(E_{elec}+\varepsilon_{fs}r^{2}\right)+\left( n-1\right)\times E_{elec}\times m\] \[= m\times\left[\left(2n-1\right)E_{elec}+\varepsilon_{fs}\times n \times r^{2}\right].\]  
Comparing the energy consumption of two communication modes, if the energy consumption of a multi-hop is less than that of a single hop, i.e.,  
\[m \times \left[\left(2n-1\right)E_{elec}+\varepsilon_{fs}\times n\times r ^{2}\right] \tag{22}\] \[<m\times\left(E_{elec}+\varepsilon_{fs}\times n^{2}\times r^{2} \right).\]  
Then, it can be devised as  
Figure 5:0  
Note that \(E_{elec}=50\) nJ/bit and \(\varepsilon_{fs}=10\) pJ/bit/m\({}^{2}\), when \(n=2\), it can be found that \(r>70\) m. Therefore, the energy consumption of multi-hop communication is less than that of single hop communication when \(r>70\) m. This mechanism is beneficial to the average energy dissipation of the network and prolongs the lifetime of network. The Algorithm 1 of the proposed protocol is shown below:  
```
1.\(N\)-number of nodes, \(r\)-number of rounds. 2. The first step is to initialize the network parameters for WSN. 3. The second step is the random deployment of the nodes in the network. 4. The third step is the deployment of the BS in the network. 5. Calculate \(d_{tBS}\)
6. for\(i=1\) to \(r\)
7.\(E_{a}=E_{i}(1-\frac{r}{r_{max}})/n\)
8.\(p_{i}=p*n*E_{i}*E_{i}/(E_{i}*E_{a})\)
9.\(T(s_{i})=p_{i}/(1-p_{i}(r\bmod(1/p_{i})))\)
10. t=Random number
11. If \((t\leq T(s_{i}))\)
12. CH \(\gets n_{i}\)
13. Calculate \(d_{tbcCH}\)
14. end if
15. if \((d_{tbcCH}<d_{tbB})\)
16. Select CH and join the cluster;
17. else
18. Nodes do not participate in the cluster
19. end if
20. Transfer to BS
21. i=i+1
22. go to step 6
23. end if
```  
**Algorithm 1**IEE-LEACH  
The conventional LEACH-based protocols do not consider the energy adjustment parameter, which exhausts the node energy quickly. However, the proposed IEE-LEACH protocol introduces four energy parameters when selecting the threshold, i.e., initial energy of nodes, residual energy of nodes, total energy of the network, and average energy of all nodes. This mechanism can balance the energy distribution of all nodes and improve energy efficiency. In addition, to decrease the energy consumption, the node closer to the BS than the CH will not participate in the cluster formation. Therefore, the robustness of the network is improved and the lifetime of the network is increased. Furthermore, the proposed protocol compares the energy consumption of single hop and multi-hop communication modes in data transmission. Then, the communication mode with less energy consumption will be adopted.