# A Novel Procedure of Enhancing the Throughput of a Mode-2 Sidelink Based on Partial Sensing
## 5 Conclusions  
The proposed method of combining the partial sensing results obtained from each P-UE provides a throughput comparable to that of full sensing while maintaining the merit of power saving offered by partial sensing. From the extensive simulations performed in a mode-2 sidelink environment, that is, CPE, it was observed that the proposed method increased the maximum throughput of each P-UE 4.94-fold when there were five P-UEs compared to that in the conventional partial sensing method. When the total number of P-UEs was 40, the throughput increased 4.11-fold due to the increase in the overhead and resource occupancy.  
The maximum number of P-UEs that can be supported by the proposed method was limited to 40 because of the quantity of PSCCH resources required for each of the reporting P-UEs. Thus, the proposed method was modified such that only some P-UEs (rather than all of them) for each time slot reported their partial sensing results to the RSU. Consequently, the maximum number of P-UEs that can be served by the proposed method can be increased in accordance with the reduced number of reported P-UEs. When the number of reporting P-UEs decreases to one, which allows for the maximum number  
Figure 10: Collision probability.  
Figure 9: Throughput and overhead of the modified proposed method.  
of P-UEs to increase to 55, the throughput performance is considerably inferior to the case in which the number of reporting P-UEs exceeds one. This is because the collision probability is high when only a single P-UE reports its partial sensing result to the RSU. As the number of reporting P-UEs exceeds one, the collision probability decreases rapidly, resulting in a throughput comparable to the case of employing all eight P-UEs as reporters. Consequently, based on the simulation results, it appears to be most suitable to use two reporting P-UEs. The simulation result regarding the required number of reporting P-UEs to fully exploit the merit of the proposed method may change depending on various environmental parameters, such as the transmit power, and the coverage of the RSU and each P-UE, which were set to 28 and 22 dBm, and 100 and 50 m, respectively.  
All of the approaches discussed in this paper were implemented under the assumption that there exists a single RSU among a number of P-UEs whose resources are to be properly allocated without collision. If there exists a number of RSUs in a given sidelink, meaning that there are multiple sets of P-UEs, each including a number of P-UEs sharing their sensing results via their own RSU, the sensing results of every RSU should also be shared. This scenario of multiple RSUs is left for future research. The realization of this scenario may yield results with greater practical value while imposing extra complexity and latency.  
Conceptualization, S.K.; Data curation, S.K.; Formal analysis, S.K.; Funding acquisition, S.C.; Investigation, S.K.; Methodology, S.K.; Project administration, S.K.; Resources, S.C.; Software, S.K.; Supervision, S.C.; Validation, S.K.; Visualization, S.K.; Writing-original draft, S.K.; Writing-review & editing, S.C. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the Commercialization Promotion Agency for R&D Outcomes (COMPA) funded by the Ministry of Science and ICT (MSIT). [2020K000081].  
Not applicable.  
The authors would like to thank the anonymous reviewers for their careful review and constructive comments.  
The authors declare no conflict of interest.