Table 1 Notations used in the proposed methodology.
Notation | Description |
|---|---|
\(\:{T}_{i}\left(t\right)\) | Task generated by vehicle \(\:i\)at decision epoch \(\:t\), defined by ⟨\(\:{D}_{i},{C}_{i},D{L}_{i}\)⟩ |
\(\:{D}_{i}\) | Input data size of task \(\:i\)(bits) |
\(\:{C}_{i}\) | Required CPU cycles for task \(\:i\) |
\(\:D{L}_{i}\) | Execution deadline for task \(\:i\)(ms) |
\(\:{a}_{t}\) | Offloading action selected at decision epoch \(\:t\)(0: local execution; \(\:k\): offload to RSU \(\:k\); \(\:r\in\:\left[\text{0,1}\right]\): task split ratio) |
\(\:{L}_{t}\) | End-to-end latency of the task executed at epoch \(\:t\)(s) |
\(\:{E}_{t}\) | Total energy consumed for task execution at epoch \(\:t\)(J) |
\(\:{R}_{t}^{\text{comp}}\) | Binary task completion indicator at epoch \(\:t\)(1 if completed within deadline, else 0) |
\(\:\alpha\:,\beta\:,\gamma\:,\delta\:,\nu\:\) | Weighting coefficients in the optimization objective and reward function |
\(\:{L}_{tx}\) | Uplink transmission delay for task offloading (s) |
\(\:{L}_{proc}\) | Processing delay at the MEC server or OBU (s) |
\(\:{L}_{rx}\) | Downlink reception delay for task results (s) |
\(\:{f}_{\text{MEC}}\) | CPU processing rate of the MEC server (cycles/s) |
\(\:{f}_{\text{OBU}}\) | CPU processing rate of the onboard unit (cycles/s) |
\(\:{T}_{\text{proc}}^{\text{MEC}}\) | Processing time of task at the MEC server (s) |
\(\:{T}_{\text{proc}}^{\text{loc}}\) | Processing time of task executed locally on the OBU (s) |
\(\:{R}_{\text{link}}\) | Achievable wireless link data rate (bits/s) |
\(\:W\) | Channel bandwidth (Hz) |
\(\:{\text{S}\text{I}\text{N}\text{R}}_{\text{e}\text{f}\text{f}}\) | Effective signal-to-interference-plus-noise ratio |
\(\:{P}_{\text{CPU}}\) | Power consumption of the onboard CPU (W) |
\(\:{P}_{\text{TX}}\) | Power consumption of the wireless transmission module (W) |
\(\:{E}_{i}^{\text{comp}}\) | Energy consumed for local computation of task \(\:i\)(J) |
\(\:{E}_{i}^{\text{tx}}\) | Energy consumed for transmitting task \(\:i\)to MEC (J) |
TCR | Average task completion ratio over the observation window |
\(\:{B}_{j}\) | Total busy time of the MEC server at RSU \(\:j\)(s) |
\(\:{p}_{j}\) | Utilization ratio of the MEC server at RSU \(\:j\) |
\(\:{h}_{v}\) | Number of RSU handovers experienced by vehicle \(\:v\) |
\(\:\stackrel{\prime }{H}\) | Mean number of handovers per vehicle |
\(\:{T}_{\text{obs}}\) | Total observation period for performance evaluation (s) |
\(\:{n}_{v}\) | Vehicle density (vehicles per km\(\:{}^{2}\)) |
\(\:G=({g}_{x},{g}_{y})\) | RSU grid dimensions along horizontal and vertical axes |
\(\:{d}_{\text{RSU}}\) | Distance between adjacent RSUs (m) |
\(\:{R}_{\text{cov}}\) | Coverage radius of an RSU (m) |
\(\:{\Omega\:}\) | Mean RSU overlap factor (average number of RSUs within vehicle coverage) |
