Communication advances Chapter | 2 21includes the IEEE 802.11p standard (Jiang & Delgrossi, 2008) and the IEEE
1609 (IEEE, 2007) upper layer communication family of standards. The latter
contains a set of standards that define the details of V2V and V2I communica-
tion such as (1) the IEEE 1609.2 standard that handles communication security,
(2) the IEEE 1609.3 standard for setting up and managing WAVE connections,
and (3) the IEEE 1609.4 standard which combines IEEE 802.11p Physical
(PHY) layer and Medium Access Control (MAC) layer to provide better man-
agement of the higher layers across multiple channels.
The IEEE 802.11p standard has been used for V2V communications for
many years (Bai & Krishnan, 2006; Vinel, 2012 ). It has most of the features of
the IEEE 802.x family of standards, which means that it is simple and provides
mechanisms for distributed MAC. It has not yet been fully adopted, mainly
because of the reliability, resilience, and stability issues that it as. However,
its main issue is that it is not open and requires that both communication par-
ties use the same equipment. Several automotive applications on the market are
used the IEEE 802.11p standard and test it on real cases, and many manufactur-
ing companies (of both vehicles and vehicle electronics) are launching research
projects in collaboration with the academia in order to study all aspects of the
protocol application in the V2V and V2I communications. The applications can
be grouped into three major types, depending on the aspect that they examine—
(1) safety, (2) traffic, and (3) user comfort.
2.4.1 Safety-related applications
The applications in this group set many real-time response constraints that the
IEEE 802.11p standard does not provide alone. So they perform several extensions
in order to allow the development of safety applications (Bohm & Jonsson, 2009).
The communication can be either multipoint or p2p but requires low-latency for
real-time interaction. Information, such as position and speed can be exchanged
between vehicles (V2V) and collected in each one of them in order to allow driv-
ers to have a better idea of the surrounding traffic. This is extremely helpful in bad
weather conditions that reduce driver’s vision such as heavy snow, rain, or fog or
in blind-road spots (e.g., at intersections, sharp turns, or behind-bulk vehicles).
Another example is when an emergency-vehicle needs to inform the vehicles in
front for the urge to reach a destination as soon as possible. This can be done by
using the communication standard to transmit an emergency message. The latter
scenario also makes use of V2I communication by sending a message to the traf-
fic management operators to intervene in the traffic lights all along its path, thus
early reducing traffic ahead. In the opposite way, the emergency-vehicle driver is
alerted for possible queues in front in order to prevent a possible collision.
2.4.2 Traffic-management applications
This group of applications is based on information exchange about vehicles’
position and speed in order to collect useful data for real-time traffic analytics by
the traffic management operators. Analytics can support better traffic planning