An Error Probability Approach to MIMO Wiretap Channels

TL;DR

This paper analyzes the probability of eavesdroppers decoding messages in MIMO wiretap channels and proposes a code design criterion using lattice codes to enhance security.

Contribution

It introduces a new approach based on error probability analysis to design MIMO lattice wiretap codes, including fading channel scenarios.

Findings

Derived a code design criterion minimizing Eve's decoding probability

Analyzed the Alamouti code as an example

Extended analysis to block and fast fading channels

Abstract

We consider MIMO (Multiple Input Multiple Output) wiretap channels, where a legitimate transmitter Alice is communicating with a legitimate receiver Bob in the presence of an eavesdropper Eve, and communication is done via MIMO channels. We suppose that Alice's strategy is to use a codebook which has a lattice structure, which then allows her to perform coset encoding. We analyze Eve's probability of correctly decoding the message Alice meant to Bob, and from minimizing this probability, we derive a code design criterion for MIMO lattice wiretap codes. The case of block fading channels is treated similarly, and fast fading channels are derived as a particular case. The Alamouti code is carefully studied as an illustration of the analysis provided.