## 3 System Model and Problem Formulation  
### System Model  
As presented in Figure 1, the system consists of an ES deployed at a BS/RSU and N TaVs with intensive tasks. Vehicles can be expressed as \(\mathcal{N}=\{1,2,\cdots,N\}\). In addition, task vehicle n is represented as TaVn and the profile of TaVn's task as \(\text{I}_{n}=\{\text{D}_{n},\text{App}_{n},\tau_{n}\}\), where the three items represent data size (in bits), task processing density (in CPU cycles/bit), and maximum tolerable latency (in seconds), respectively. The total CPU cycles required to complete the task is \(\text{C}_{n}=\text{D}_{n}\text{App}_{n}\)[23]. Moreover, the channels of TaVs adopt \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Ref.** & **Year** & **Loc** & **SeV** & **Edge** & **Velocity** & **Advantages** & **Shortcomings** \\ \hline
[8] & 2021 & ✓ & ✓ & ✗ & ✗ & ✗ & A virtual queue model is proposed to optimize partitioning & The velocity of vehicle is not given & The mobility of vehicles is not considered \\
[9] & 2023 & ✓ & ✓ & ✗ & ✗ & ✗ & ✗ & ✗ & ✗ \\
[10] & 2022 & ✗ & ✓ & ✗ & ✗ & ✗ & ✗ & Multiple SeVs can provide service for a TaV & Only one TaV is considered \\
[11] & 2020 & ✗ & ✓ & ✗ & ✓ & ✗ & ✗ & ✗ & Pekative velocity is considered and BS is used for information management \\
[12] & 2022 & ✓ & ✓ & ✗ & ✓ & Vehicles are motivated to form coalitions to operate the resources cooperatively & Non-orthogonal multiple access is considered & of nearby vehicles \\
[13] & 2022 & ✓ & ✗ & ✓ & ✗ & ✗ & ✓ & V2V links are used to be aware of the surrounding environment and the potential offloading of EEs & Each TaV can offload data to only one ES \\
[14] & 2023 & ✓ & ✗ & ✓ & ✓ & The offloading probability of TaVs are considered & Handover problem between different MEC platforms is not considered \\
[15] & 2020 & ✓ & ✗ & ✓ & ✗ & The aggregers are classified into three categories & Information management needs to be considered \\
[16] & 2020 & ✓ & ✓ & ✓ & ✗ & Both SeV and ES can provide services once & Only one terminal can be chosen \\
[17] & 2022 & ✓ & ✓ & ✓ & ✗ & V2V migration and I2I migration are used to transfer the computing results & Only one task of a TaV is considered \\
[18] & 2022 & ✓ & ✓ & ✓ & ✓ & Multiple offloading modes are considered & Multiple offloading modes are considered & A computation task of a TaV is considered \\
[19] & 2023 & ✓ & ✓ & ✓ & Vehicle velocity distribution is analyzed & The time-varying or stochastic V2V channel gain is not considered \\
[20] & 2019 & ✓ & ✗ & ✓ & ✓ & Integrating load balancing with offloading is proposed & The arriving vehicle has a constant speed \\
[21] & 2019 & ✗ & ✓ & ✓ & ✗ & Task is generated in time period and V2I2V offloading is considered & Local computing resources is not used \\ Ours & ✓ & ✓ & ✓ & ✓ & The offloading mode can be chosen adaptively & A TaV has only one task \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison with the latest related studies. orthogonal frequency division multiple access method. Each TaV has a corresponding SeV, namely, SeVn. Then, the SNR of TaVn to BS/RSU and to SeVn can be expressed as  
\[\gamma_{n}^{edg}=\mathrm{P}_{n}^{edg}g_{n}^{edg}\Big{/}\delta^{2}, \tag{1}\]  
\[\gamma_{n}^{v2v}=\mathrm{P}_{n}^{v2v}g_{n}^{n^{\prime}}\Big{/}\delta^{2}, \tag{2}\]  
where \(\mathrm{P}_{n}^{edg}\) and \(g_{n}^{edg}\) represent the transmitting power and channel gain of TaVn to BS/RSU. Similarly, \(\mathrm{P}_{n}^{v2v}\) and \(g_{n}^{n^{\prime}}\) represent relevant parameters between TaVn and SeVn. We adopt the urban channel model [24; 25] for V2I and V2V links.