To Obtain or not to Obtain CSI in the Presence of Hybrid Adversary

TL;DR

This paper investigates the impact of different levels of channel state information (CSI) on secure communication rates in a wiretap channel with a hybrid adversary capable of jamming or eavesdropping, revealing that less CSI can sometimes be more beneficial.

Contribution

It analyzes the value of various CSI acquisition methods in the presence of a hybrid adversary, highlighting scenarios where no CSI yields higher secrecy rates.

Findings

Main CSI is more valuable to the adversary than jamming CSI.

In some ergodic scenarios, no CSI can outperform having CSI in terms of secrecy rates.

The value of CSI varies depending on the communication scenario and adversary capabilities.

Abstract

We consider the wiretap channel model under the presence of a hybrid, half duplex adversary that is capable of either jamming or eavesdropping at a given time. We analyzed the achievable rates under a variety of scenarios involving different methods for obtaining transmitter CSI. Each method provides a different grade of information, not only to the transmitter on the main channel, but also to the adversary on all channels. Our analysis shows that main CSI is more valuable for the adversary than the jamming CSI in both delay-limited and ergodic scenarios. Similarly, in certain cases under the ergodic scenario, interestingly, no CSI may lead to higher achievable secrecy rates than with CSI.