## 4 Analytical Results
Even for larger spatial jitter values, however, the boresight should be taken into consideration for the design of THz links, as indicated in Figure 1. Consequently, the performance comparison between the first two figures mainly reveals the impact of generalized pointing errors on the ABER performance of single-hop or multi-hop THz systems. Figure 2: ABER vs. transmitted power for single-hop and quad-hop THz link configurations under different weather conditions, weak turbulence, FSPL, moderate water vapor concentration and weak generalized pointing errors. Figure 3 illustrates the ABER evolution for the dual-hop LOS THz link configuration over a wide range of transmitted power through weak-to-strong atmospheric turbulence, weak ZB pointing errors, different transceiver antenna gains, clear weather along with moderate-to-high air humidity conditions. For the same transceiver gain of \(G=55\) dBi along with the same amount of pointing mismatch, it is highlighted that the impact of stronger water vapor concentrations along with stronger atmospheric turbulence significantly degrade the total THz ABER performance. It is also highlighted that especially for low transmitted power values, the impact of attenuation due to water vapor dominates. In fact, the worst-case scenario in Figure 3 is that represented by the blue solid line. Although there is a performance improvement as turbulence becomes weaker (blue dashed line),a better performance improvement can be observed when attenuation due to water vapor becomes weaker (red solid line) instead of turbulence. Consequently, it is demonstrated that the detrimental impact of attenuation due to water vapor is more important than the impact of turbulence-induced scintillations on the THz outage performance. The latter is qualitatively consistent with the experimental results in [11; 14] that highlight that the atmospheric turbulence-induced scintillations are much less detrimental for THz links than molecular attenuation. Additionally, Figure 3 illustrates the potential of the utilization of more effective transceiver antennas of a higher gain \(G=70\) dBi, in an attempt to overcome turbulence, pointing errors and especially, high water vapor concentrations. Once again, these depicted outage performance improvements are qualitatively in accordance with the corresponding results obtained in several works. Figure 4 shows the ABER evolution for the triple-hop LOS THz link configuration over a wide range of transmitted power through strong atmospheric turbulence, strong NZB pointing errors, different operation frequencies, clear weather along with moderate-to-high air humidity conditions. It becomes evident from the illustrated results that even for strong joint turbulence and generalized pointing errors, the impact of THz signal's attenuation due to water vapor still drastically increases the total ABER of the system. Additionally,  
Figure 3: ABER vs. transmitted power for a dual-hop THz link configuration with different antenna gains, weak-to-strong turbulence, moderate-to-high water vapor concentrations and weak ZB pointing errors. it is highlighted that further significant ABER performance degradations are observed by increasing the operational frequency from \(f=0.3\) THz to \(f=0.35\) THz, especially for lower transmitted power values. This is consistent with the findings reported in Figure (3.1) of [60] which indicate that molecular attenuation due to water vapor becomes more significant in the region of 0.35 THz in comparison with the region of 0.3 THz. Consequently, although it appears that increasing the frequency of the carrier wave could have a positive contribution to establish THz links of a higher available bandwidth, particular attention should be given to the molecular attenuation due to water vapor.