On the impact of quantized channel feedback in guaranteeing secrecy with artificial noise

Abstract

Physical-layer secrecy in wireless fading channels has been studied extensively in recent years to ensure reliable communication between the transmitter and the receiver subject to constraints on the information attainable by the eavesdropper. With multiple antennas at the transmitter, Goel and Negi proposed the use of artificial noise (AN) in the null space of the receiver's channel to corrupt the eavesdropper's reception, which helps guarantee secrecy without knowledge of the eavesdropper's channel. It has been shown that the secrecy capacity can be made arbitrarily large by increasing the transmission power, when perfect knowledge of the receiver's channel direction information (CDI) is available. However, in practice, this is not possible due to rate-limitations on the feedback channel. This paper studies the impact of quantized channel feedback on the secrecy capacity achievable with artificial noise. We show that, with imperfect CDI at the transmitter, the AN that was originally intended only for the eavesdropper may leak into the receiver's channel and limit the achievable secrecy rate. To maintain a constant performance degradation, the number of feedback bits must increase at least logarithmically with the transmission power. Moreover, we observe that the portion of power allocated to the transmission of AN should decrease as the number of quantization bits decreases to alleviate the degradation due to noise leakage.

Principles of Physical Layer Security in Multiuser Wireless Networks: A Survey

“…• The effects of imperfect and quantized CSIT of the main (Alice-to-Bob) channel upon the secrecy rate were examined in [62] and [63], respectively, while bounds on secrecy capacity with imperfect CSIT and limited ARQ feedback were given in [64], [65]. MIMOME secrecy rate maximization with imperfect CSIT of all channels was solved using an iterative algorithm in [66] via a Taylor series expansion to convexify the secrecy rate.…”

On the Impact of Quantized Channel Feedback in Guaranteeing Secrecy with Artificial Noise: The Noise Leakage Problem

“…However, to the best of our knowledge, these issues have not been addressed before in the context of secret communications. Compared to our previous works [10], [11], we improve the bit scaling law for the MISOSE case in [10] by removing some approximation steps, and provide detailed proofs for the results in [11]. The results on the AN power allocation and the impact of CQI have not been presented before.…”

A saddlepoint approximation to the distribution of the sum of independent non‐identically beta random variables

“…Sum of beta random variables arises in many applied areas: analysis of PERT networks ( Sculli & Wong , ); software reliability estimation ( Adams , ); project management processes ( Klein , ); maximal ratio combining in cellular MIMO‐CDMA downlink systems ( Ma et al , ); the impact of quantized channel feedback in guaranteeing secrecy with artificial noise ( Liang et al , ); to mention but a few.…”