Environment Aware Virtual
Vehicle-to-Vehicle System Design
To ensure a robust automotive design against environment variations, a virtual software platform is key.

Dedicated Short Range Communications (DSRC) deployment is coming for vehicle-to-vehicle (V2V) communications. Module vendors and vehicle system integrators have commenced working in the design stage and are finding a series of issues impacting their module design or system integration that are out of their control (due to environment variations affecting vehicles on the road).

The environment changes depend on where the vehicles are located, i.e. rural, urban, or highway areas. In addition, the DSRC IEEE 802.11P standard specifies the V2V radio channel conditions include rural line-of-sight (LOS), urban approaching LOS, street crossing non-line-of-sight (NLOS), highway LOS, and highway NLOS.

Module vendors, car companies, and system integrators must devise a way to put together systems that operate with high connectivity and reliability in all these environments. Ignoring this challenge prior to deployment can cause market deployment delays and additional implementation cost.

One way to address the above challenge is to have design processes that can include a wide variety of environmental scenarios, to ensure a robust design in reducing the number of costly field road tests required. To achieve this, we need a virtual software platform emulating the environment, and meet the IEEE 802.11P physical layer requirements. The good news is, this virtual road test platform is already a reality.

Consider the radio channel for a pair of vehicles with NLOS at a major street crossing (as seen in Figure 1).

Initially, the two cars don’t have communication until
they clear the corner building. Once this is completed,
performance challenges are primarily equated to the
distance between the cars, relative speed, and angle
between the vehicles. These physical parameters are
directly responsible for signal loss, delay, doppler shift,
etc. The communication system needs to overcome for
a reliable transfer of information. System designers are
then faced with the possibility of having to perform
field driving tests in many locations with non-repeatable
conditions. These include weather, total number of
vehicles, and interferers which are not controllable
and can vary significantly with time. Having a software
platform to emulate this in a virtual environment will help
pre-deployment design and integration of the different
modules and components for the V2V communication
system since all these variables can be controlled. A virtual
software strategy that includes IEEE 802.11P standard
compliant physical layer emulation will contribute to the
system design, making the design more reliable and robust.

Figure 1: Street crossing NLOS urban scenario.

The physical properties of the vehicle will also impact the communication link. Consider the location of the communication radio antenna on the vehicle. It’s worth noting there’s a limited set of locations where the antenna can be placed. Take for example, a dipole antenna which has a typical radiation pattern as shown in Figure 2a. The same antenna (when mounted on a car) will have the pattern altered (as seen in Figure 2b) due to the presence of the vehicle body. As the vehicle moves in the NLOS scenario under consideration, the angle between the vehicles changes, which in turn means the receive and transmit antennas line-of-sight angle also changes. As the angle shifts, so does the overall antenna gain between transmitter and receiver. This gain change would not occur if the perfect dipole antenna pattern had been preserved once the antenna was mounted. Antenna gain changes coupled to a communication channel that’s also changing due to the relative movement of the vehicles, means keeping track of all these dynamics—this will involve more than just a classical channel link analysis.