Method for quality assessment of hands-free phone call using hardware-in-the-loop techniques

This paper presents a method for assessing hands-free phone calls quality in an actual car infotainment system using Hardware-in-the-Loop (HiL) simulations. Hands-free is a Bluetooth profile that allows the communication between the owner’s phone and its car Bluetooth system which is a common feature in modern cars. This work aims to give a quantitative evaluation of the hands-free feature performance when receiving a phone call according to accepted quality standards in the industry. To do this, several HiL tests were made simulating an incoming call situation where the driver has a smartphone paired via Bluetooth with the vehicle infotainment system. After call acceptance, a 1 kHz tone is sent from the calling phone to the driver’s phone and the output of interest is the electrical signal sent to the vehicle’s speakers representing the audio information. This signal is acquired by a Real Time System (RTS) that analyzes the similarities of the original sent signal with the received one by the measurement of the fundamental frequencies and Total Harmonic Distortions (THD). The test procedure is completely automated with the help of automation tools, i.e. Froglogic Squish and Appium. The former was used to simulate the touch action of the user in the car infotainment system which is required to accept the incoming call in the proprietary company HMI and the latter to automate the caller phone in order to initiate the phone call. This way it is possible to make several automated tests routines in sequence much faster than in a manual fashion and acquire a representative quantity of data to make assumptions about the system performance quality. This method provided a low cost setup, without specialized hardware besides the HiL standard tools already available, and reliable results to investigate hardware and software issues that were before impossible to be found.