Test methodologies for connected vehicles(2)

In other words, to deliver the medium term baseline service vision, automotive wireless connectivity solutions embedded into the vehicle will need to support LTE, 3G and 2G, as well as Wi-Fi 802.11 air interfaces. Each air interface needs to be tested separately across worst case network conditions that the vehicle is likely to encounter and interoperability between each air interface needs to be tested thoroughly.

Intelligent transport systems
Wireless connectivity that enables intelligent transport systems and vehicle safety solutions are based on extensions to existing Wi-Fi standards, which operate close to the 6GHz frequency range. In order to verify continuous vehicle-to-vehicle (V2V) connectivity, automotive manufacturers need to–early in the development cycle–conduct lab-based testing that accurately replicates on-road radio network conditions. Latency is a key consideration since it ultimately dictates the speed threshold that the system can safely operate.

Ensuring wireless connectivity performance and reliability
Signal interference issues can arise as a result of the extreme proximity of multiple radio transceivers within the vehicle where the transmit power of one transmitter may be much higher than the received power level of another receiver. In some coexistence scenarios, such as when different radio technologies within the vehicle operate on adjacent frequencies, current state-of-the-art filter technology might not provide sufficient signal rejection. This problem is further compounded by fact that final material composition of the vehicle is not known until late in the development cycle and consequently interference modes and paths become increasingly difficult to predict in real world network connection scenarios. These radio design challenges can be addressed by conducting testing as described below.

Mobile test industry developments
Test methodologies used in the mobile device industry–where there is already a strong focus on performance, low cost and shorter development cycles–can easily be adopted by the automotive industry. For example, the virtual drive testing concept–a lab-based performance and interoperability test solution–has been proven to accelerate product rollouts and quality assurance testing by integrating industry-leading lab and field test tools with a sophisticated test automation environment.

Virtual drive testing significantly reduces field testing by accurately replicating field mobility scenarios. Data captured in the field is used to build tests that replay drive or indoor routes in a virtual environment by emulating real-world RF network conditions in the laboratory. This replay can be performed with real network infrastructure or with a network simulator.

The majority of wireless connectivity technology resides in an embedded Telematics Control Unit (TCU). Automotive wireless systems use an Over-the-Air (OTA) test methodology to perform interoperability and performance testing first on the telematics unit including antenna cluster in the lab, and later on the prototype vehicle with the telematics unit and antenna cluster integrated.

Multiple Input Multiple Output (MIMO) OTA performance testing is used to assess user experience by replicating real-world radio network conditions as seen by the vehicle antenna cluster. MIMO OTA testing uses channel emulators in conjunction with either an anechoic chamber or a reverberation chamber to accurately emulate urban, suburban, rural, and indoor radio environments.

Automotive system developers also benefit from verifying that the data throughput performance of in-vehicle software and hardware modules complies with operator requirements from multiple geographic regions under real-world network conditions prior to final integration. The use of operator acceptance and data throughput tests enables the automotive industry to drastically reduce their performance-related test effort and highlight system issues that impact quality of experience much earlier in the vehicle development cycle.

The ability to successfully realise the vision and initiatives set out by the automotive industry and various governments will ultimately depend on manufacturers' ability to deliver robust, stable and flexible vehicle connectivity platforms. The manufacturer of a vehicle has to address a number of challenges when integrating a wide range of technologies to support future applications and services. By using testing methodologies deployed in the mobile device development industry, the automotive industry will be able to optimise their test regimes to deliver an enhanced Connected Car experience.

About the author
Steve Barraclough is Strategic Business Development Manager at Anite.