Information Technology Reference
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vehicles in an on-demand fashion. Figure 14.6 depicts the information flow
chart of V2R-based navigation systems. Figures 14.7 and 14.8 show two dif-
ferent network architectures of V2R-based navigation systems, which were
proposed in [9,13]. In Figure 14.7, wireless sensors are installed along the
roadside to collect local traffic information. The roadside sensors transmit
collected information to BSs using multi-hop relay. By doing so, the deploy-
ment density of BSs can be greatly reduced. In Figure 14.8, DSRC roadside
units are responsible for collecting real-time traffic information and trans-
mit it to WiMax BSs. The WiMax BSs are organized as a wireless mesh net-
work. That is, remote BSs can transmit its traffic information to TIC using
multi-hop relay. Since the transmission range of WiMax is about 50 km, and
the transmission bandwidth of WiMax is about 70 Mbps, the deployment
density of BSs can be very small.
TIC is responsible for merging local real-time traffic information,
generating routing information, and transmitting routing information to all
vehicles. There are two ways to generate routing information: proactive and
reactive. In the proactive approach, the routing information is generated
periodically. That is, for each source position, the quickest paths from
the source position to all potential destination positions are periodically
calculated and broadcasted to all vehicles. In implementation, both source
Local traffic info.
Navigation request
Local traffic info.
Navigation request
Roadside
units/base
stations
Traffic
information
center
Vehicles
Routing info.
Routing info.
Figure 14.6
Information flow chart of V2R-based navigation systems.
TIC
Roadside unit
(sensor node)
Base station
Figure 14.7
Network architecture used in a wireless mesh network for real-time vehicle guidance.
