SYSTEM DESIGN
A. VANET-based Information Distribution and Estimation
The network topology considered here is shown in Figure
2. There are two traffic information sources. The first one is
to use the on-board GPS device and the electronic road
database for the vehicle to identify its current GPS location
and record the information like the instantaneous driving
speed in its memory when the vehicle starts to drive on the
road. As the flow shown in Figure 3, the on-board GPS
device detects whether it has passed through an intersection,
which indicates an end of the road segment. If yes, all
recorded driving speeds are averaged and stored in the
AverageSpeed field for traffic information of this road
segment, as listed in Table 1, with correct values in the
RoadSegmentID and RecordTime fields, which specifies the
time when the vehicle leaves this road segment.