Alamouti space-time coding in car-to-car communications - SDR-based implementation and measurement

Car-to-car (C2C) communications requires reliable connectivity at moderate data rates. This is essential for safety-related applications. The development of such communication systems needs to cope with time-variant propagation channels and rich multipath environments. Moreover, the choice of the antennas and their position in/on the car highly influences the overall propagation channel. This paper proposes a measurement method by means of software-defined radio systems. That is, USRP N210 modules are used for implementation of IEEE 802.11p physical layer aspects at 5.9 GHz. Moreover, this standard is extended for using spatial diversity at transmitter and receiver side. For this, Alamouti space-time coding is implemented for exploitation of transmit diversity in combination of maximum ratio combining at the receiver side. Thus, four USRP modules are used in a 2×2 communication system while placing two transmit and two receive antennas at different positions on the car.