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ception buffers. This allows higher priority packets
to overtake less important ones.
• Signature Processing: As shortly introduced
above, V2XC calls for trustworthy information.
As we cannot assure the correctness of sensor
values obtained by remote vehicles, we assure at
least trustworthiness of the data by checking
properties of the issuing platform, i.e. the sending
on-board unit (OBU). This is done using ignatures
and certificates. Security functions are pooled in a
special security module [12],[13]. It performs signature
and certificate verifications for all incoming
packets and generates signatures for all outgoing
ones. Based on the IEEE WAVE security
standard [8] the Elliptic Curve Digital Signature
Algorithm (ECDSA) is implemented. To achieve
the required throughput, the processing is completely
done in specialized cryptographic hardware
and encapsulated in the module that can easily
be duplicated if there is need for more
throughput.
• Separation of Domains: By principal, V2XC
opens the internal architecture to outside communication.
Hence a malicious attacker may attempt
Denial-of-Service (DoS) attacks to influence the
overall vehicle’s behavior. Considering safety
relevant functions this may result in serious accidents
or even dead passengers. So protecting the
cars functionality is mandatory for each V2XC
OBU. FPGAs offer the unique opportunity to
physically divide Inter-VND and IntraVND and
connect them via a distinguished interface (firewall).
In our approach a dual ported memory
block serves as connection between both domains.
The memory block is split into two disjunct
regions. The two domains have write access
to one of the not-overlapping blocks but are able
to read both blocks. On each side the respective
module decides whether to process the incoming
data or not. Especially the IntraVND decides
when to take data offered by the InterVND. Additionally
high level protocols can pass the firewall
in another region. As the in-car environment is
considered to be trustworthy, information from
this side is directly given to the InterVND without
additional check.
E. Simulation-based Validation of V2XC Systems
Since V2XC systems have to fulfill a lot of different
requirements concerning high performance and functionality,
an intensive evaluation and investigation is
necessary in order to be able to optimize the overall
system architecture. From a more abstract perspective,
a V2XC system interacts with the two domains network
and environment. The network domain provides
stimulus in terms of network packets and the environmental
domain provides stimulus in terms of sensor
data.
6
PROCESSOR SOLUTIONS FOR SMART MOBILITY
Fig. 10: V2X-ACC-in-the-loop.
In this context, the simulation-based approach proposed
in [14] allows a flexible adaption to the test case
by being able to interconnect an arbitrary number of
simulators of the different domains system, network
and environment. It targets comprehensive design
space exploration, verification, and test of V2XC
system models. Therefore several SystemC based
architecture models can be integrated into a simulation
framework that allows observation of system behavior
and interaction.
In [15] the approach is extended towards capabilities
for more continuous and holistic considerations. The
ideas from [14] are included into the so called V2Xin-the-Loop
platform. The base frame of the platform
is given by the so called X-in-the- Loop framework
[16] which describes a consistent and integrated development
environment for drive systems. Thereby,
”X” stands for the unit under test (UUT) which is in
our case the complete vehicle equipped with the
V2XC system. The V2X-in-the-Loop platform extends
the environmental domain by the domains vehicle
and driver. Generally, each of them can be either
virtual or real which allows evaluating and investigating
interactions and interaction chains between real as
well as virtual and real systems and sub-systems.
In Fig. 10 an instance of the platform is exemplarily
illustrated that is used for evaluating the impact of a
V2XCbased adaptive cruise control system (ACC) on
the braking behavior of a real driver. Thereby, the
driver is sitting in the real vehicle which is running on
a roller test-bench or controls it via a driving simulator.
Both, real driver and real vehicle are embedded
into a virtual environment that simulates surrounding
traffic on microscopic level. Furthermore, the real
wireless network channel of the vehicle is connected
to a virtual wireless network communication channel
that allows V2XC between real and virtual vehicles.
IV. CONCLUSION AND OUTLOOK
Single-core based processor solutions are not
enough in order to cope with the performance requirements
of future general purpose and safetycritical
applications. New multicore solutions are
necessary to accelerate future applications. However,