  Millimeter wave (mmWave) vehicular communica tion systems have the potential
to improve traffic efficiency and safety. Lack of secure communication links,
however, may lead to a formidable set of abuses and attacks. To secure
communication links, a physical layer precoding technique for mmWave vehicular
communication systems is proposed in this paper. The proposed technique
exploits the large dimensional antenna arrays available at mmWave systems to
produce direction dependent transmission. This results in coherent transmission
to the legitimate receiver and artificial noise that jams eavesdroppers with
sensitive receivers. Theoretical and numerical results demonstrate the validity
and effectiveness of the proposed technique and show that the proposed
technique provides high secrecy throughput when compared to conventional array
and switched array transmission techniques.
