Privacy via Modulation Rotation and Inter-Symbol Interference
career value
237K/year
🤖 AI Summary
This study addresses the challenge of achieving differential privacy at the user end of communication systems without introducing additional noise or energy consumption. The work proposes two novel physical-layer mechanisms: first, applying a deterministic phase rotation to BPSK signals at the transmitter that is unknown to the receiver; and second, intentionally inducing inter-symbol interference (ISI). Both approaches implicitly provide privacy by altering signal structure or reducing decision distances, thereby eliminating the need for explicit noise addition. This work is the first to leverage modulation rotation and controllable ISI as formal differential privacy mechanisms, demonstrating that non-ideal hardware characteristics can be proactively exploited to circumvent the overhead of conventional methods. Theoretical analysis and simulations confirm that both schemes offer effective privacy guarantees, with the ISI-based approach exhibiting input-distribution-dependent privacy leakage—maximal under equiprobable inputs.
Application Category
📝 Abstract
Two physical-layer mechanisms for achieving user-side differential privacy in communication systems are proposed. Focusing on binary phase-shift keying (BPSK) modulation, differential privacy (DP) is first studied under a deterministic phase rotation applied on the BPSK modulation at the transmitter, while the receiver is assumed to be unaware of the rotation angle. In this setting, privacy is achieved through an effective reduction in the decision distance, resulting in a controlled increase in the bit error rate (BER) without explicit noise injection. Next, a BPSK transmission scheme with intentionally induced inter-symbol interference (ISI) is studied, where the receiver is likewise unaware of the deterministic timing offset that generates the ISI. Unlike the rotated BPSK scheme, the DP obtained via ISI is shown to depend explicitly on the input data distribution. In particular, numerical results demonstrate that, for a fixed ISI parameter, the privacy loss is maximized when the binary input symbols are equiprobable. While conventional DP mechanisms rely on artificially added noise, often incurring additional energy or communication costs, it is shown that structured modifications, such as modulation rotation or induced ISI inherent to realistic communication channels can itself provide DP guarantees. While the analysis focuses on deterministic transmitter modifications unknown to the receiver, it is noted that real-world devices naturally introduce unintentional rotations or ISI due to hardware nonidealities and implementation errors. These effects can therefore provide a level of privacy without requiring explicit noise injection. Hence, it is possible to avoid deliberately perturbing the data, instead leveraging inherent device imperfections to achieve privacy guarantees with no additional privacy cost.
Problem
Research questions and friction points this paper is trying to address.
differential privacy
physical-layer privacy
modulation rotation
inter-symbol interference
BPSK
Innovation
Methods, ideas, or system contributions that make the work stand out.
differential privacy
modulation rotation
inter-symbol interference
physical-layer privacy
BPSK
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