Addressing the wireless digital communication system

a sufficient condition to ensure the physical-layer security transmission is derived from the viewpoint of information theory

and a space hopping secure transmission method is proposed

which can mask the characteristic of finite alphabets.First

since the multi-antenna eavesdropper in the finite-alphabet-input system possesses the architecture of Discrete Noisy Lossless Channel (DNLC)

it can reconstruct the secret signal and invalidate the artificial noise method.As a result

destroying the eavesdropper's DNLC architecture becomes a sufficient condition for ensuring the security of system transmission.Then

utilizing the diversity and uniqueness of wireless channel characteristics

a space hopping secure transmission method based on the Multiple Input Multiple Output (MIMO) system is proposed.It switches receiver/transmitter antennas and transmits spatial scrambling during the information transmission

which can mask the finite alphabet characteristic of the secret signal and destroy the eavesdropper's DNLC architecture.Finally

theoretical analysis and simulation results demonstrate the efficacy of the secure method.