Algorithm 1: Multi-Hop Path Latency Calculation

Input: $\mathrm{source}\mathrm{vehicle}{\mathcal{v}}_n$ $,\mathrm{target}\mathrm{RSU}{\mathcal{r}}_m$ $,\mathrm{task}\mathrm{data}\mathrm{size}{\mathcal{D}}_{\mathcal{i}}$

Output: $\mathrm{best}\mathrm{path}{\mathcal{P}}^{\mathrm{*}}$ $,\mathrm{minimum}\mathrm{latency}{\mathcal{L}}^{\mathrm{*}}$

$1:\mathrm{Initialize}{\mathcal{L}}^{\mathrm{*}}\leftarrow \infty$, ${\mathcal{P}}^{\mathrm{*}}$ ← None

$2:R_{access}\leftarrow \mathrm{Get}\mathrm{all}\mathrm{RSUs}\mathrm{directly}\mathrm{connected}\mathrm{to}\mathrm{vehicle}{\mathcal{v}}_n$

$3:\mathrm{Create}\mathrm{RSU}-\mathrm{only}\mathrm{subgraph}{\mathcal{G}}_{\mathcal{r}}$

$4:\mathbf{for}\mathrm{each}{\mathcal{r}}_{access}$$\mathrm{in}{R}_{access}$ do

$5:{\mathcal{L}}_{v2r}\leftarrow \mathrm{Get}\mathrm{V}2\mathrm{R}\mathrm{Latency}({\mathcal{v}}_n$$,{\mathcal{r}}_{access}$$,{\mathcal{D}}_{\mathcal{i}}$)

$6:\mathbf{if}{\mathcal{r}}_{access}$$\mathrm{is}{\mathcal{r}}_m$ then

$7:{\mathcal{L}}_{path}$ $\leftarrow {\mathcal{L}}_{v2r}$

$8:{\mathcal{P}}_c$$\leftarrow [{\mathcal{v}}_n$$,{\mathcal{r}}_m$]

9:            else

$10:\mathrm{Define}\mathrm{edge}\mathrm{weights}\mathrm{in}{\mathcal{G}}_{\mathcal{r}}$ as R2R latency:

$11:\mathbf{for}\mathrm{each}\mathrm{edge}({\mathcal{r}}_u,{\mathcal{r}}_v$$)\mathrm{in}{\mathcal{G}}_{\mathcal{r}}$ do

$12:W$ $({\mathcal{r}}_u,{\mathcal{r}}_v$ $)\leftarrow \mathrm{Get}\mathrm{R}2\mathrm{R}\mathrm{Latency}({\mathcal{D}}_{\mathcal{i}},{\mathcal{r}}_u,{\mathcal{r}}_v$ $)\mathrm{for}\mathrm{all}\mathrm{edges}\mathrm{in}{\mathcal{G}}_{\mathcal{r}}$

13:      end for

$14:{\mathcal{P}}_{v2r}$$\leftarrow \mathrm{Shortest}\mathrm{Path}({\mathcal{G}}_{\mathcal{r}}$$,\mathrm{source}={\mathcal{r}}_{access}$$,\mathrm{target}={\mathcal{r}}_m$$,\mathrm{weights}=W$)

$15:\mathbf{if}{\mathcal{P}}_{v2r}$ exists then

$16:{\mathcal{L}}_{r2r}$ $\leftarrow \mathrm{Calculate}\mathrm{total}\mathrm{latency}\mathrm{of}{\mathcal{P}}_{v2r}$ $\mathrm{using}\mathrm{weights}W$

$17:{\mathcal{L}}_{path}$ $\leftarrow {\mathcal{L}}_{v2r}$ $+{\mathcal{L}}_{r2r}$

$18:{\mathcal{P}}_c$$\leftarrow [{\mathcal{v}}_n$] ⊕${\mathcal{P}}_{r2r}$ // ⊕ is path concatenation

19:      else

20:        continue

21:      end if

22:          end if

$23:\mathbf{if}{\mathcal{L}}_{path}$$<{\mathcal{L}}^{\mathrm{*}}$ then

$24:{\mathcal{L}}^{\mathrm{*}}$ $\leftarrow {\mathcal{L}}_{path}$

$25:{\mathcal{P}}^{\mathrm{*}}$ $\leftarrow {\mathcal{P}}_c$

26:          end if

27:  end for

$28:\mathbf{return}{\mathcal{P}}^{\mathrm{*}}$ $,{\mathcal{L}}^{\mathrm{*}}$