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Wireless Communications
Applications at
DaimlerChrysler
BY BEIJING WANG, MAJEED KADI, AND STEVE MUENCH
he task of incorporating the most up-to-date,
advanced wireless technology in their cars and
trucks may seem daunting to automotive manufacturers.
Recent consumer trends hint that on-board
navigations systems are one of the most desirable
features in a vehicle, second only to safety-related
features. Not surprising, because according to the
J. D. Power survey from October 2004, the number
of vehicles offering some type of navigation package is on the rise.
Besides navigational systems, the demand for satellite radio and
hands-free phone capabilities is also growing. Wireless technology
looks promising to assist automobile manufacturers in meeting
consumers’ increasing expectations for mobility, road safety,
system capacity/efficiency and in-vehicle entertainment features.
In this article, we’ll discuss the steps taken by the DaimlerChrysler
Chrysler Group (CG) to meet these expectations and some of the
communication applications that are expected to affect the
automotive industry in the future.
NAVIGATION
Navigation systems, used in both military and civil applications,
employ wireless signals transmitted via a global positioning
system (GPS). The GPS is based on 24 satellites orbiting the earth
(Fig. 2). The satellites act as reference points from which navigation
systems triangulate their positions. The GPS was developed by
the U.S. Department of Defense and can be used for civil and
military applications for no subscription cost.
In concept, at any given time, all GPS satellites are defined
in their orbits in space. A navigation system can mathematically
define a satellite’s unique position by knowing its relative
distance to at least four satellites simultaneously. The distance from
each satellite is calculated by knowing the time the
satellite signal took to reach the navigation system. A time
delay is calculated based on the time shift between the received
code from the satellite and a similar code generated by the
navigation receiver.
The mathematical calculations performed to determine
location (based on travel distance) is correct, but it assumes ideal
conditions. In reality, using the pure signal provided from the
GPS, the navigational system has an accuracy of no more than
30 meters. Inaccuracies are due to multiple factors including
clock errors, atmospheric delays, multipath and receiver
errors—assuming there is no intentional error added for security
measures by the U.S. Department of Defense. All of these errors
make the implementation of an in-vehicle navigation system a
very challenging task.
The accuracy of a vehicle navigation system is the product of
accurate map databases, powerful real-time processing capability
and multiple redundancy calculations, in addition to sophisticated
algorithms of map matching that have the capability of receiving
and processing the vehicle linear speed and the real-time vehicle
orientation using an on-board gyrometer. Currently, assuming
good system implementation and an accurate map in the area,
there is easily a 10-meter accuracy in vehicle navigation units.
The CG’s navigation system offers consumers various
features, for example, user-friendliness, routing capability,
real-time traffic (international markets only), system response
speed, map and routing display clarity, carefully designed
human machine interface (HMI) screens, GPS clock,
customized personal menu, point of interest (POI) feature,
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