Enhancing the real-time performance of a wireless hardware-in-the-loop test system in ISM bands

This paper presents a spectrum agile real-time wireless communication gateway (RT-WCGW) concept that is intended to replace the common wired communication interfaces between a hardware-in-the-loop (HIL) test system and an automotive electronic control unit (ECU). It makes the bidirectional transfer of time-critical control, diagnostics, and calibration (CoDiCa) data wireless and hence increases the HIL test setup flexibility as well as opens up novel opportunities for testing automotive ECUs or autonomous driving systems. The introduced approach applies the robust physical layer IEEE 802.11p and exploits multiple parallel radio front ends. This configuration enables a multi-channel operation and enhances the deterministic dynamic spectrum access in the coexistence-afflicted 2.4GHz industrial, scientific, and medical (ISM) frequency band required for real-time wireless CoDiCa data transmission. In addition, an adaptive spectrum access procedure is introduced that provides compliance with the revised European spectrum regulations in terms of the mandatory listen-before-talk mechanism. By employing interference measurements and link-level simulations the real-time performance of the RT-WCGW is characterized and evaluated under realistic coexistence conditions. The results show that the real-time capability of the RT-WCGW can be significantly improved by utilizing the multi-channel approach making it practicable for novel HIL test applications.