An adaptive secret transmission rate scheme in SIMO wireless wiretap channel

An adaptive secret transmission rate scheme with secret outage probability constraint in SIMO wireless wiretap channel is proposed to consider the physical layer security issue for the wireless communication with secrecy outage. The channel estimation and channel fading characteristics are used to obtain the channel state information (CSI) about the channel from the transmitter to the legitimate receiver (the main channel) and the CSI about the channel from the transmitter to the eavesdropper (the eavesdropper's channel), respectively. When the CSI about the main channel is known while the CSI about the eavesdropper's channel is not known by the transmitter, the secrecy rate is adjusted according to the CSI of the main channel and the probability density function of the eavesdropper's channel, and the emission threshold is obtained according to the definition of secrecy outage. Then the secrecy throughput is maximized in the condition of satisfying the constraint of secrecy outage probability. The quasi-static Rayleigh fading channel is used in the simulation. Simulation results show that when secrecy outage probability is lower than 0.1 and the antenna number of the legitimate receivers is no less than that of eavesdropper, the secrecy throughput of the proposed approach is twice that of the previous methods for SISO system, and that as long as there are sufficient antennas in the legitimate receiver, the secrecy throughput of SIMO system is larger than that of SISO system even if the antenna number of the legitimate receivers is smaller than that of eavesdropper.