TY - JOUR
T1 - Delay-intolerant covert communications with either fixed or random transmit power
AU - Yan, Shihao
AU - He, Biao
AU - Zhou, Xiangyun
AU - Cong, Yirui
AU - Swindlehurst, A. Lee
N1 - Publisher Copyright:
© 2005-2012 IEEE.
PY - 2019/1
Y1 - 2019/1
N2 - In this paper, we study delay-intolerant covert communications in additive white Gaussian noise (AWGN) channels with a finite block length, i.e., a finite number of channel uses. Considering the maximum allowable number of channel uses to be N , it is not immediately clear whether the actual number of channel uses, denoted by n , should be as large as N or smaller for covert communications. This is because a smaller n reduces a warden's chance to detect the communications due to fewer observations, but also reduces the chance to transmit information. We show that n = N is indeed optimal to maximize the amount of information bits that can be transmitted, subject to any covert communication constraint in terms of the warden's detection error probability. To better make use of the warden's uncertainty due to the finite block length, we also propose to use uniformly distributed random transmit power to enhance covert communications. Our examination shows that the amount of information that can be covertly transmitted logarithmically increases with the number of random power levels, which indicates that most of the benefit of using random transmit power is achieved with just a few different power levels.
AB - In this paper, we study delay-intolerant covert communications in additive white Gaussian noise (AWGN) channels with a finite block length, i.e., a finite number of channel uses. Considering the maximum allowable number of channel uses to be N , it is not immediately clear whether the actual number of channel uses, denoted by n , should be as large as N or smaller for covert communications. This is because a smaller n reduces a warden's chance to detect the communications due to fewer observations, but also reduces the chance to transmit information. We show that n = N is indeed optimal to maximize the amount of information bits that can be transmitted, subject to any covert communication constraint in terms of the warden's detection error probability. To better make use of the warden's uncertainty due to the finite block length, we also propose to use uniformly distributed random transmit power to enhance covert communications. Our examination shows that the amount of information that can be covertly transmitted logarithmically increases with the number of random power levels, which indicates that most of the benefit of using random transmit power is achieved with just a few different power levels.
KW - Covert communications
KW - covertness
KW - delay-intolerant
KW - finite blocklength
KW - random transmit power
UR - http://www.scopus.com/inward/record.url?scp=85048474237&partnerID=8YFLogxK
U2 - 10.1109/TIFS.2018.2846257
DO - 10.1109/TIFS.2018.2846257
M3 - Article
SN - 1556-6013
VL - 14
SP - 129
EP - 140
JO - IEEE Transactions on Information Forensics and Security
JF - IEEE Transactions on Information Forensics and Security
IS - 1
ER -