Covert OFDM transmission using CDD based frequency selective channel

Orthogonal Frequency Division Multiplexing (OFDM) has become an increasingly common technique in communication systems and raised tremendous security concerns recently. This paper proposes to achieve covert OFDM transmission with cyclic delay diversity (CDD) featured multiple input multiple output (MIMO) technology. Particularly, our physical layer security scheme takes the advantage of CDD formed frequency selective channel and addresses uneven comb pilots to confuse unauthorized receivers and benefit authorized receivers. Numerical results justify that, with our design, the CDD paradigm can efficiently safeguard OFDM system, and the performance can be further optimized by fine tuning channel estimation for authorized users.