# Resource Allocation in C-V2X Mode 3 Based on the Exchanged Preference Profiles
## 4 Resource Allocation via Matching
### Exchanged Preference Profiles
As can be observed in Figure 10, the CUEs' total transmission capacities for all algorithms except the MCM algorithm increased linearly with the number of V2V links since an increase in V2V links could accordingly provide more RBs for the V2I links. In addition, as \(\alpha\) increased, the optimality finding capability of our proposed algorithm was enhanced. For the MCM algorithm, when the number of V2V links was larger than that of V2I links, the total available RBs in the system remained unchanged since the algorithm in [8] limited the number of V2V links and V2I links to be equal. Moreover, to pursue a higher fairness, the Hungarian algorithm was iteratively executed in the algorithm of [8], leading to overly stable allocation results. Thus, when the number of VUEs reached 60, the capacity performance was no longer affected by the number of V2V links. \[U_{m}(k)=\mathbb{E}\Big{\{}{W\text{log}\Big{(}1+{\gamma_{k,m}^{V}}^{*}\Big{)}} \Big{\}} \tag{15}\]0 The vehicular link’s outage ratio performance of different schemes with varying V2I links. In Figure 11, we compare the V2V links' outage ratio of the five schemes under different V2V link numbers. Except for the random selection, increasing the number of V2V links degraded the outage ratio performance of the allocation schemes. This was because the number of V2V links with bad channel conditions increased when the set of VUEs enlarged. In addition, our proposed algorithm with three \(\alpha\) values had better performance in outage ratio performance compared to the MCM algorithm and the random selection. When the number of VUEs reached 60, the outage ratio performance of the algorithm in [8] declined sharply since the MCM algorithm did not consider the resource allocation problem for the extra VUEs. In this paper, we also regarded the extra V2V links as the outage links. Due to the randomness in the resource allocation process, the outage ratio of the random selection scheme was maintained at a poor level and was less affected by the number of V2V links. \[U_{m}(k)=\mathbb{E}\Big{\{}{W\text{log}\Big{(}1+{\gamma_{k,m}^{V}}^{*}\Big{)}} \Big{\}} \tag{15}\]1 The total capacity performance of different schemes with varying V2V links. \[U_{m}(k)=\mathbb{E}\Big{\{}{W\text{log}\Big{(}1+{\gamma_{k,m}^{V}}^{*}\Big{)}} \Big{\}} \tag{15}\]2 The fairness performances of different schemes with varying V2V links. ## 6 Conclusions

In this paper, we investigated the RB allocation problem in the C-V2X mode 3 considering the different QoS requirements of VUEs and CUEs. We first established the system communication model and introduced the effective capacity and queuing theory to characterize the V2V link's maximum constant service data rate under the constraint of latency requirement. Then, we formulated the joint power control and RB allocation problem based on the \(\alpha\)-fair function to maximize the CUEs' total capacities with an \(\alpha\)-fair function, while guaranteeing the allocation fairness and the reliability of each V2V link. To solve this formulated problem, we proposed a novel matching-game-theoretic algorithm based on the exchanged preference profiles of the two participant sets. In the simulation, we investigated the effects of the \(\alpha\) parameter and different structures of the vehicular network on the CUEs' capacities, fairness among CUEs, and V2V links' outage ratio. Simulation results demonstrated that our proposed algorithm was greatly affected by the \(\alpha\) parameter and outperformed other resource allocation algorithms. Conceptualization, D.Y. and D.H.; methodology, D.Y. ; software, D.Y. ; validation, D.Y.and D.H.; formal analysis, D.Y. ; investigation, D.Y., D.H. and X.C. ; resources, X.C. ; data curation, X.C. ; writing--original draft preparation, D.Y. ; writing--review and editing, D.Y., D.H. and X.C. ; visualization, D.Y. ; supervision, X.C. ; project administration, X.C. All authors have read and agreed to the published version of the manuscript. This research received no external funding. The authors declare no conflict of interest.