Vehicle-to-vehicle wireless channel characterization using digital signal processing

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Supervisor:
Dr. Horváth Péter
Department of Broadband Infocommunications and Electromagnetic Theory

Vehicle to Vehicle communications (V2V) can contribute decreasing road accidents and it can give us information abot the ever-changing traffic- and weather conditions in real time. But because of the continuous movement of the transmitter and the reciever, the changing terrain and different electromagnetic impacts, the V2V and other purpose mobile radio channels show time-changing transmissions. That's why it is so important to have a relevant model of the channel and its statistical characterisation.

Knowing the channel's time variant transfer characteristics, we are able to characterise it statistically. There are some protocolls and standards which rely on the statistical data such as coherence time and coherence bandwidth.

For measurements it is required to prepare a proper measuring signal (also called as sounding signal) which has a low crest factor for good efficency and covers the frequency band that is going to be measured.

It is recommended to calculate the transfer characteristis using digital signal processing (DSP). But before starting the real measurements some testing must be done on the algorithm calculating the channel characteristics in favor of being accurate and reliable.

My task was to develop a channel measuring system based on a multisine signal, and to write a program calculating the transfer characteristics. The sounding signal is mixed up to the appropriate frequency band and is released to the antenna by a USRP2 software radio. On the reciever end the signal coming from the antenna is digitalized by a USRP2 too.

Visualizing the transfer characteristics in real time has numerous advantages. At the end of my thesis I wrote the DSP software in C++ language on which I did run-time optimisation.

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