LPD Communication: A Sequential Change-Point Detection Perspective

Abstract

In this paper, we establish a framework for low probability of detection (LPD) communication from a sequential change-point detection (SCPD) perspective, where a transmitter, Alice, wants to hide her signal transmission to a receiver, Bob, under the surveillance of an adversary, Willie. The new framework facilitates to model LPD communication and further evaluate its performance under the condition that Willie has no prior knowledge on when the transmission from Alice starts and that Willie wants to detect the existence of the communication as quickly as possible in real-time manner. We consider three different sequential tests for Willie, i.e., the Shewhart test, the cumulative sum (CUSUM) test, and the Shiryaev-Roberts (SR) test, to model the detection procedure. Communication is said to be covert if it stops before detection by Willie with high probability. Covert probability defined as the probability that Willie is not alerted during the communication procedure is investigated. We formulate an optimization problem aimed at finding the transmit power and transmission duration such that the total amount of information that can be transmitted is maximized subject to a high covert probability. Under Shewhart test, closed-form approximations of the optimal transmit power and transmission duration are derived, which well approximate the solutions obtained from exhaustive search. As for CUSUM and SR tests, we provide an effective algorithm to search the optimal solution. Numeric results are presented to show the performance of LPD communication.

Jamming Aided Covert Communication with Multiple Receivers

“…). Note that (28) differs from (13) in the sense that in (28), the signal matrices obtained in different time blocks are collected together to make a decision, while in ( 13), the decision is made based solely on the signal matrix obtained in a single time block.…”

“…Some recently efforts have been devoted to improving the covert communication performance. It has been revealed that by exploiting the adversary's uncertainty on the statistical information of its channel outputs, the covert communication performance can be greatly improved, and in some cases, non-vanishing covert communication rates exist, for example, when the adversary has uncertainty on its noise power [9], [10] or when the adversary is uncertain about the transmission time [11]- [13].…”

Robust Beamforming Design for Covert Communications

“…which is a convex SDP. Let W opt c,1 denote the optimal solution of problem (23). Due to relaxation, the rank of W opt c,1 may not equal to one.…”

“…Next, we consider the design of w b . Let w opt c,1 denote the beamformer of problem (23). Then, let P c = w opt c,1 2 denote the transmission power of w opt c,1 .…”

“…Fortunately, some works have revealed that Alice can achieve a positive covert rate under some given conditions, i.e., imperfect knowledge of noise [12]- [14]; imperfect channel statistics [15], [16]; unknown transmission time [17]- [19]; the presence of random jamming signals [20], [21]; finite blocklengths of transmissions [22], [23]; the existence of relay [24]- [26]; and appearance of injecting artificial noise (AN) [27], [28]. To be more specific, in [25], the authors proposed…”