## 6 Performance Evaluation Results
### Comparison with a BER of \(10^{-6}\)  
Figure 6 presents a comparison of the goodput (vs delay) of three different protocol options and their hybrid for file transmission over the primary and secondary cislunar communication paths with a BER = \(10^{-6}\). A general observation in Figure 6a, in comparison with a BER of 0, is that the goodput of most DTN protocol options slightly decreases at all the link delays because of bundle corruptions caused by the introduction of a channel BER of \(10^{-6}\). An exception happens for the performance of UDP LTP PRIM, which remains about the same as at a BER of 0. This implies that the performance of UDP LTP PRIM is not affected by link delay and channel noise. This is because its file transfer is mainly controlled by unreliable UDP-based transmission. However, in comparison to a BER of 0, the overall performance rank of all four protocol options remains about the same. This is because the increase in BER from 0 to \(10^{-6}\) does not affect the data transmission severely, as only a very limited number of bundles are corrupted on average.  
Similar to Figure 5a, a direct observation in Figure 6a is that LTP LTP PRIM outperforms all other protocol options throughput all the link delays over both relay paths, with an even more significant performance advantage than that with a BER = 0. With the increase in the delay, the goodput of other three protocol configurations merges. Figure 6b provides statistical analysis results for this observation. We observe that both \(P\)-LTP TCP SEC vs. UDP LTP PRIM and \(P\)-LTP UDP SEC vs. UDP LTP PRIM tend to increase from about 0 to above 0.1 for the delay increase from 1280 ms to around 4500 ms. In addition, the absolute goodput differences between each pair of protocols (i.e., LTP TCP SEC-LTP UDP SEC, LTP TCP SEC-UDP LTP PRIM, and LTP UDP SEC-UDP LTP PRIM) drop from a range of 1300-450 bytes/s to around 0 bytes/s.  
As shown in Figure 5b, LTP LTP PRIM is not compared with any other protocol options in Figure 6b because its goodput advantage over others is obvious.  
With the increase in the delay, the goodput of LTP TCP SEC drops drastically, but it is still the second highest for the delays of 1280 ms\(\sim\)3500 ms. As discussed, UDP LTP PRIM shows consistent performance at all the link delays, and it has the lowest goodput in the delay range of 1280 ms-3500 ms. \(P\)-LTP TCP SEC vs. UDP LTP PRIM in Figure 6b indicates that the \(p\)-value of their difference is originally very low (below 0.05) up to 3500 ms, but it increases to 0.4, 0.8 and 0.16 at 4000-5000 ms, respectively. This explains that LTP TCP SEC has significant goodput advantage over UDP LTP PRIM for short delays up to 3500 ms,  
Figure 6: Goodput (vs link delay) comparison of three different protocols and their hybrid over the primary and secondary cislunar communication paths with a BER of \(10^{-6}\). (a) Goodput. (b) Goodput differences and \(p\)-values.  
but the advantage disappears for longer link delays. A similar result is observed for the comparison between LTP UDP SEC and UDP LTP PRIM, as illustrated by \(P\)-LTP UDP SEC vs. UDP LTP PRIM. For the link delay longer than 3500 ms, LTP UDP SEC drops below UDP LTP PRIM--we observed that LTP UDP SEC-UDP LTP PRIM changes roughly linearly from the initial 450 bytes/s to \(-250\) bytes/s.