Transmit Antenna Selection with Alamouti Scheme in MIMO Wiretap Channels

TL;DR

This paper introduces a transmit antenna selection scheme combined with the Alamouti scheme to improve physical layer security in MIMO wiretap channels without eavesdropper CSI, demonstrating lower secrecy outage probability.

Contribution

A novel TAS-Alamouti scheme for MIMO wiretap channels that enhances security without requiring eavesdropper channel information.

Findings

Lower secrecy outage probability compared to single TAS scheme.

Effective in nonidentical Rayleigh fading channels.

Improves security at higher SNR levels.

Abstract

This paper proposes a new transmit antenna selection (TAS) scheme which provides enhanced physical layer security in multiple-input multiple-output (MIMO) wiretap channels. The practical passive eavesdropping scenario we consider is where channel state information (CSI) from the eavesdropper is not available at the transmitter. Our new scheme is carried out in two steps. First, the transmitter selects the first two strongest antennas based on the feedback from the receiver, which maximizes the instantaneous signal-to-noise ratio (SNR) of the transmitter-receiver channel. Second, the Alamouti scheme is employed at the selected antennas in order to perform data transmission. At the receiver and the eavesdropper, maximal-ratio combining is applied in order to exploit the multiple antennas.We derive a new closed-form expression for the secrecy outage probability in nonidentical Rayleigh fading, and using this result, we then present the probability of non-zero secrecy capacity in closed form and the {\epsilon}-outage secrecy capacity in numerical form. We demonstrate that our proposed TAS-Alamouti scheme offers lower secrecy outage probability than a single TAS scheme when the SNR of the transmitter-receiver channel is above a specific value.