# Assessment of Affordable Real-Time PPP Solutions for Transportation Applications
## 3 Results
It can be seen that, for the RT-BKG scenarios, about 90% of the 2D position discrepancies are less than 0.22 m for the RT-BKG-GR, RT-BKG-GE, and RT-BKG-GRE solutions, with slight superiority for the RT-BKG-GRE solution. However, they dramatically increase to 0.4 m for the RT-BKG-G solution. On the other hand, the two-dimensional errors are within 0.2 m, 0.3 m, 0.42 m, and 0.5 m for 90% of the time using the RT-CNE-GE, RT-CNE-GRE, RT-CNE-G, and RT-CNE-GR solutions, respectively, with obvious superiority in the RT-CNE-GE scenario. The position differences in the horizontal component for the RT-WHU processing strategy are within 0.3 when the GR, GE, and GRE solutions are used; nevertheless, they are approximately 0.38 m in the GPS solution. The outperformance of the RTK scenarios is notable because 90% of the horizontal positioning errors are smaller than 0.02 m.  
As another analysis perspective, it can be seen that a four-decimeter-level horizontal positioning accuracy (i.e., 0.4 m) can be accomplished about 90% of the time when using the BKG GPS instantaneous satellite orbit and clock correction products. Conversely, this accuracy is achieved about 95% of the time when using the BKG GPS/GLONASS SRR  
Figure 7: CDF of the two-dimensional positioning errors for the RT-PPP and RTK scenarios. corrections. Moreover, this percentage increases to 98% for both the GPS/Galileo and GPS/GLONASS/Galileo scenarios. For the GPS CNE orbit and clock products, 85% of the RT-PPP solution outputs achieve a 0.4 m positioning accuracy; however, this percentage drastically decreases to 65% when the GPS and GLONASS correction products are both employed. Meanwhile, the CNE Galileo SSR products significantly increased the percentage to about 98% of the position estimates with 0.4 m horizontal accuracy. Likewise, the WHU Galileo orbit and clock corrections fostered two-dimensional positioning accuracy when they were applied to the GPS and GPS/GLONASS RT-PPP solutions, as about 98% of the 2D estimates were less than 0.4 m. Furthermore, both the WHU GPS and GLONASS SSR corrections are accurate enough that about 95% of the estimates have four-decimeter horizontal accuracy. In general, the Galileo SSR corrections from the three analysis centers are more accurate than the GPS and GLONASS SSR corrections; furthermore, GLONASS real-time orbit and clock products have some limitations regarding their accuracy. A histogram of the two-dimensional positioning differences is presented in Figure 8 to evaluate the accuracy of the proposed RT-PPP and RTK approaches. When the RT-BKG solution is applied, the 2D error range is less than 0.6 m for the RT-BKG-G solution and less than 0.45 m for the RT-BKG-GR solution; furthermore, it is lower than 0.35 m and 0.3 m for the RT-BKG-GE and RT-BKG-GRE solutions, respectively. Furthermore, it can be seen that the 2D error is under 0.3 m in 66%, 96%, 94%, and 98% of the epochs for the RT-BKG-G, RT-BKG-GR, RT-BKG-GE, and RT-BKG-GRE solutions, respectively. For RT-CNE, the extent of the two-dimensional discrepancy is no more than 0.6 m for both the RT-CNE-G and RT-CNE-GR solutions; on the other hand, it substantially decreases to under 0.25 m and 0.3 m for the RT-CNE-GE and RT-CNE-GRE scenarios, respectively. In the same context, around 67%, 48%, 99%, and 91% of the 2D discrepancies are less than 0.3 m when the RT-CNE-G, RT-CNE-GR, RT-CNE-GE, and RT-CNE-GRE scenarios are adopted, respectively. For the RT-WHU solution, the horizontal positioning error distribution is below 0.4 m for all scenarios, and 2D errors are less than 0.3 m approximately 63% and 86% of the time using the RT-WHU-G and RT-WHU-GR strategies, respectively. However, these percentages increase to 91% and 92% when the RT-WHU-GE and RT-WHU-GRE strategies are employed, respectively. Figure 8: _Cont._  
In the RTK scenario, the spread of two-dimension positioning differences is less than 0.035 m and 0.03 m for the RTK-G and RTK-GR solutions, respectively, while it is no more than 0.02 m for both the RTK-GE and RTK-GRE solutions.