(*)<..................>(*)<..................>(*)
      |                      |                      |
+-----------+          +-----------+          +-----------+
|           |          |           |          |           |
| +-------+ |          | +-------+ |          | +-------+ |
| |IP-OBU1| |          | |IP-RSU1| |          | |IP-OBU3| |
| +-------+ |          | +-------+ |          | +-------+ |
|     ^     |          |     ^     |          |     ^     |
|     |     |=====>    |     |     |          |     |     |=====>
|     v     |          |     v     |          |     v     |
| +-------+ |          | +-------+ |          | +-------+ |
| | Host1 | |          | | Host2 | |          | | Host3 | |
| +-------+ |          | +-------+ |          | +-------+ |
|           |          |           |          |           |
+-----------+          +-----------+          +-----------+
   Vehicle1                 EN1                  Vehicle3

 <----> Wired Link   <....> Wireless Link   ===> Moving Direction
 (*) Antenna