Blind MIMOME Wiretap Channel with Delayed CSIT

TL;DR

This paper characterizes the secure degrees of freedom in the Gaussian MIMOME wiretap channel with delayed CSIT, providing a complete solution for all antenna configurations and improving existing schemes through advanced artificial noise alignment.

Contribution

It offers the first complete characterization of SDoF for all antenna setups in this channel model, introducing new inequalities and an improved artificial noise alignment scheme.

Findings

Complete SDoF characterization for all antenna configurations.

New inequalities for analyzing signal dimensions with delayed/no CSIT.

Enhanced artificial noise alignment scheme.

Abstract

We study the Gaussian MIMOME wiretap channel where a transmitter wishes to communicate a confidential message to a legitimate receiver in the presence of eavesdroppers, while the eavesdroppers should not be able to decode the confidential message. Each node in the network is equipped with arbitrary number of antennas. Furthermore, channels are time varying, and there is no channel state information available at the transmitter (CSIT) with respect to eavesdroppers' channels; and transmitter only has access to delayed CSIT of the channel to the legitimate receiver. The secure degrees of freedom (SDoF) for such network has only been characterized for special cases, and is unknown in general. We completely characterize the SDoF of this network for all antenna configurations. In particular, we strictly improve the state-of-the-art achievable scheme for this network by proposing more efficient artificial noise alignment at the receivers. Furthermore, we develop a tight upper bound by utilizing 4 important inequalities that provide lower bounds on the received signal dimensions at receivers which supply delayed CSIT or no CSIT, or at a collection of receivers where some supply no CSIT. These inequalities together allow for analysis of signal dimensions in networks with asymmetric CSIT; and as a result, we present a converse proof that leads to characterization of SDoF for all possible antenna configurations.