Technical Blogs

The in-vehicle infotainment (Apple CarPlay testing)
2017 2017-09-08

Technological development is changing the auto/driving experience and creating an ecosystem that supports connectivity between automobile and mobile applications. According to China Industrial Development Research Network report, the global car network terminals can reach 66.95 million units. China’s car network terminal was only 1 million units in 2013, expected to grow to around 10 million units in 2018. The “mobile phone-car mode” network terminal increased from 19% in 2013 and will increase to nearly 50% in 2018.

Automobile connectivity will improve traffic safety and also make traffic more efficient. The concept of car network connectivity is changed by "V2X (Vehicle-to-Everything)", divided into: Vehicle to Vehicle (V2V), Vehicle to Infrastructure (V2I) Vehicle to People (V2P) and Vehicle to Network (V2N). For V2X, the car is like a large mobile intelligence device that can be linked to the Internet, navigation and driving system, traffic monitoring and even unmanned applications for "safe", "convenient" and “comfortable “demands.

The car network application for information and entertainment (in-vehicle infotainment systems, IVI system) has a large market potential for its applications. Infotainment systems could grow in demand with more smartphones and compatibility as “Apple Carplay”, “Android Auto” and “MirrorLink” which needs to be connected to car with other in-built functions allowing drivers and passengers to take control of all kinds of information and data transmission between the car and the mobile device.

The car is no longer just a mere means of transportation, connectivity and networking application is changing the way we experience voice and interactive controls. Many manufacturers have now started making efforts to implement related technologies for better hands-free automobile communications and safety. Interoperability is a key part of the compatibility test that needs to be authorized before some OEM devices can be used with the car systems. The CarPlay certification requires a series of technical verification tests to be performed according certain requirements of part of the ITU-T standard.

Apple CarPlay put emphasis on "Car Handsfree Audio" Quality

The CarPlay was launched by Apple in 2014 to allow users drive safely while using their iPhone mobile devices. With the CarPlay, the iPhone can be connected to the car while the iPhone screen is projected to the car dashboard screen. The CarPlay technology currently supports wired (USB) and wireless (Wi-Fi, Bluetooth) modes of connections which can be controlled using voice control (Siri), touch knob and control keys.


Figure: CarPlay's modes of operation: Siri, touch and control keys (taken from Apple website)

To test and certify the CarPlay feature, Apple implements the ITU-T Telephony Audio Quality Test requirement to ensure better quality of calls. ITU-T Telephony Audio Quality Test allows real life scenarios test based on ITU-T P.1100 and P.1110 standards. The P.1100 version is designed for narrowband hands-free calling and the P.1110 version is the standard specification for wideband hands-free calling. This test requires ITU-T standard tests to cover the following four connection modes:

  1. NB(Narrow-band) CarPlay
  2. NB(Narrow-band) Bluetooth
  3. WB(Wide-band) CarPlay
  4. WB(Wide-band) Bluetooth

The reference standard for CarPlay tests using versions P.1100 and P.1110 of the ITU-T standards is based on testing for these nine areas:

  1. Delay
  2. Loudness Ratings
  3. Sensitivity Frequency Response
  4. Speech Quality During Single Talk
  5. Idle Channel Noise
  6. Out-of-band signals
  7. Echo Performance Without Background Noise
  8. Double Talk Performance
  9. Background Noise Transmission

Testing the nine items is designed to test the audio quality condition for better conversation performance. The test assesses delay time between calls, the sound quality, signal reception quality, the echo suppression, noise suppression of background noise, and other tests. In every capacity, the test simulates the real-world driving scenarios of the car using the mobile device application. Using expert equipment, each of these nine areas are tested and the result is explored to understand the auditory performance.

For example, "Background Noise Transmission" this test will simulate the impact of the noise generated by the car on the actual driving, and "Double Talk Performance" will measure the mutual interference of each other Status, and the test results are divided into five levels, namely 1,2a, 2b, 2c, 3 (refer to the following figure).

Indispensable interoperability test is needed for compatibility performance

The CarPlay tests need certain requirements to be met before endorsement for use or issuance of certification. One important condition is for all test result to be sent to Apple for verification and review of the procedures and details of the test performed. Apple demands the testing information, results and post-test updates to be delivered to ensure that the test was consistently performed with the right version of the software and hardware forms.

There is also the need for all tests to comply with the latest version of the test specification suggested by Apple. For test specifications that are in the process of being updated, Apple requires that the latest specification be tested along with details of the test tools and fixtures used in the test process. The configuration of the test set-up is delivered to Apple as part of the testing requirement.

Exacting testing requirements make its fairly challenging for manufacturers to perform self-verification test because of the capability and tools required. Allion is an authorized testing location for CarPlay USB Signal Integrity (USB SI) Test. Allion performs test in any of the following host and device modes with different speed ranges.

Figure: USB signal integrity tests

The CarPlay certification also focuses on car positioning capacity. For this certification, Apple suggests a total of eight designated routes for manufacturers to comply with and return positioning records to Apple for verification. A part of the road test requirements is the GPRMC head angle test assessed by turning the vehicle forward, backward and to stall position to check the degree rotational angle.

The CarPlay wireless connection requires the manufacturer to submit a wireless performance test for approval by Apple before testing can be permitted. Other wireless testing configurations such as Bluetooth compatibility information and wireless audio connection test are required.

Interoperability testing of vehicle applications

The CarPlay certification test requires that interoperability between the iPhone mobile device and the vehicle be tested. Interoperability is more important for smart device and accessories to connect flawlessly to the vehicle. Allion is a leading interoperability testing laboratory. With its many years of experience in testing we are able to deliver different types of interoperability testing for vehicle and smart devices. Some of the interoperability testing includes connectivity, instant messaging software operations and user scenario tests.

In general, connection technologies such as Bluetooth, USB, Wi-Fi, etc., have a standard authentication requirement which frequently brings interoperability challenges in its practical applications. Some of the interoperability issues are not only restricted to the OEM manufacturers but also from the software side such that VoIP applications may not interoperate with the other car applications.

The series of tests we execute at Allion, simulates real life scenarios such as making a phone call, accessing the car, listening to music etc., to ensure there is full interoperability between systems. Allion performs detailed compliance test against specified certifications and standards in areas such as Wi-Fi, USB, Bluetooth, DLNA, MirrorLink, and MHL to support compatibility regardless of the OEM manufacturer. With the assurances of interoperability, customers are able to rely on technologies from manufacturers to ensure vehicles are able to interact and connect to increasing mobile applications.

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