22 PART | I ITS technology enablers
as well as real-time management of emergencies. By collecting traffic data, it
is easier to regulate the traffic during a traffic jam or redirect traffic in order
to reduce delays. A more advanced application can be the implementation of a
smart network of traffic lights that will collect information about the amount of
vehicles waiting at all times and the delays they face and will consequently adjust
green light times in order to provide a smoother car flow and reduce traffic.
Using V2I communication, the road network operators are able to collect
information about vehicle flows and loads in road junctions and provide traffic
information to the drivers in real-time, thus helping them to take informed deci-
sions about the path to follow in order to avoid traffic.
The Electronic Toll Collection is another application that reduces traffic
and has been quite popular among many countries. The ETC system allows
the faster collection of tolls, gives the ability to create more flexible charging
policies, and reduces the congestion in tolls. Using the WAVE protocol, the on-
board transmitter can communicate with the antenna installed on the toll lane
and allow the vehicle to pass without stopping or reducing speed.
2.4.3 User-comfort and infotainment applications
The aim of such applications is to increase the comfort level of drivers and pas-
sengers and provide them with entertaining and informative content. Information
may relate to traffic or weather conditions ahead or can be completely irrelevant
to driving allowing passengers to relax with films or music that is streamed to
their vehicles on demand. They can also upload information to the cloud and
share it, but since it is not critical for driving it will have low-priority concerning
the use of the available bandwidth. The ongoing research in this field inflates the
expectations. However, the IEEE 802.11p has not been designed for this purpose
and can hardly support them in the case of a fast-moving vehicle or a vehicle that
is moving on a rural area, away from wifi hotspots and routers. Such applications
also raise a security issue, since in order to provide connectivity to the cloud a lot
of routers must be trusted in the path. As an alternative, such services examine
other technologies such as 3G or 4G that have been designed for such tasks.
2.5 IEEE 1609 family of standards
In order to cover dedicate short-range communication needs at all the layers
of the communication stack, the IEEE 1609 family of standards defines the
architecture of the network, the model of communication as well as the manage-
ment structure and the security mechanisms for providing high speed wireless
connectivity (>27 Mb/s) in the short-range (<1000 m) and with low-latency
between the vehicle and its surroundings.
The standard defines a simple architecture that comprises three main com-
ponents—(1) the On-board Unit (OBU) in the vehicle; (2) the Road Side Unit
(RSU) in the road infrastructure; and (3) the WAVE interface for the V2V and
V2I communication.