The market for automotive electronic devices grows every year. Indeed, we have more and more electronic devices in cars for a lot of applications like comfort, security, infotainment, ... All these devices need to communicate and this will be more important in the next years. However, these new needs bring also some new problems for the car manufacturer. One of these are the bottleneck of cable bundles between electronic control unit (ECU), actuators, sensors and many other functions. In last years, to solve this problem, some new networks have been used like the CAN and more recently the FlexRay. In this thesis, we study an other kind of network which does not need new wires: the power line communication (PLC). More precisely, the PLC is a system for carrying data on wires that are also used for electric power transmission. Moreover, with a PLC system, we can expect higher data rates than existing in-vehicle networks. This type of communication system will be interesting for ADAS and Infotainment applications, ... In a first part, we study the feasability of in-vehicle PLC devices with indoor modem. The HPAV and HD-PLC standards are studied. The measurements show data rates higher than 10 Mbps. Then, we study the PLC channel with measurements realized on four different vehicles. With these measurements, we characterized the in-vehicle PLC channel: coherence bandwidth, delay spread, background noise and impulsive noises. In a second part, we perform a simulation work to study in detail the performance of a multi-carrier transmission. We observe the influence of electrical topology, points locations, and scenarios (car with engine ON/OFF, car moving, ...). The simulation results confirm the data rates variation observed during the feasability study with indoor PLC modems. Then, we optimize two important parameters in order to maximize the bit rate: the guard interval and the inter-carrier spacing. The simulation results show that the inter-carrier spacing can be increased and the guard intercal can be reduced compare to the HPAV parameters. Finally, we show that the PHY layer for a in-vehicle PLC system have to change according to the channel and the different electrical topology. In a last part, we present a demonstrator which uses a software-defined radio platform: the USRP2 card. With this kind of testbed, all the signal processing tasks are performed on a GPP which offers a high flexibility. The preliminary results confirm those found during the simulations. Several measurements of bit rates achieved are proposed, in the band [0-12.5] MHz, for two scenarios: car engine OFF and car engine ON.
Power Line Communication study and optimization en embedded vehicle