## 7 Performance Evaluation and Analysis
As there is no secondary chain head in PEGASIS so nodal delay also increases at the primary chain head. Initially, due to congestion consideration, the nodal delay in case of C-PEGASIS is greater than 2-Chain and 4-Chain based schemes, thus it leads to more end-to-end delay in C-PEGASIS as compared to the two multi-Chain schemes. However, later on, C-PEGASIS shows less end-to-end delay as compared to the two multi-Chain schemes. Although the per node end-to-end delay in C-PEGASIS is relatively high, but this is due to the fact that a relatively fewer number of nodes are alive in C-PEGASIS (during later simulation course) as compared to the two multi-Chain schemes. Thus, the overall end-to-end delay of C-PEGASIS is then lower than the two multi-Chain schemes. Figure 10 shows the comparison of transmission loss in the discussed schemes, which has been computed by the thorp model. It depends upon the transmission distance, bandwidth efficiency and the attenuation loss of the signal. Larger distance between communicating nodes causes high transmission loss which further increases due to the death of the intermediate nodes. The single-chain based scheme has low transmission loss due to less forwarding distances between the nodes causing high bandwidth efficiency. Moreover, multi-chain schemes have low signal attenuation loss. Transmission loss in the 4-chain based scheme is also less than the 2-chain based scheme due to a fewer number of transmissions. PEGASIS has more transmission loss due to longer transmission distance between chain head and sink than that of compared schemes. On the other hand, C-PEGASIS shows more transmission loss than  
Figure 9: End-to-end delay (sec) in 4-chain, 2-chain, single chain-based routing and PEGASIS. the two multi-Chain based schemes, and less transmission loss than PEGASIS and Single-Chain based schemes due to moderate communication distance in comparison to the other two groups of schemes. Path loss of the network depends on a number of factors such as depth of sender and receiver, Euclidean distance and the loss caused by the wave movement. Path loss is computed by using the MMPE model. Figure 11 depicts the comparison of path loss between the chain-based schemes and PEGASIS. It shows similar behavior to transmission loss. In the single-chain scheme, the loss is higher than the other chain-based schemes because of the large transmission distances between the forwarding nodes. However, it decreases with the decrease in number of alive nodes. In the other two chain based schemes, smaller chains reduce the loss of the network, thereby, improving the network performance. However, single-chain has less path loss than PEGASIS due to minimized forwarding distances in the chain. In PEGASIS, path loss keeps on changing due to the random selection of chain heads. Random noise function largely affects the performance of PEGASIS due to the presence of a long link problem. C-PEGASIS shows increase and decrease in path loss till 4000 s and after 4000 s, respectively. The increase in path loss is due to distant communication whereas the decrease is due to the increase in the number of dead nodes. Moreover, the path loss of C-PEGASIS is higher than PEGASIS and Single-Chain schemes, and lower than 2-Chain and 4-Chain schemes, respectively. Figure 12 shows the comparison of network throughput of 4-chain, 2-chain, single-chain based routing schemes and PEGASIS. Network throughput in single-chain based scheme quickly decreases due to the death of forwarding nodes, which have extra load of forwarding data. It also isolates the end nodes of the chain causing the loss of their data packets. In the other two chain based routing schemes, network throughput is much higher due to less burden on the nodes of the chains. The 4-chain based scheme performs better than the 2-chain based scheme due to the balanced load distribution of the intermediate nodes of the chains. Network throughput of PEGASIS and C-PEGASIS quickly falls due to the death of intermediate nodes of the chain.