Artificial-Noise-Aided Secure Multi-Antenna Transmission with Limited Feedback

TL;DR

This paper proposes an optimized artificial-noise-aided secure multi-antenna transmission method with limited feedback, balancing throughput, secrecy, and feedback bit allocation, demonstrating near-optimal performance with minimal feedback.

Contribution

It introduces an adaptive transmission strategy that optimally allocates power and coding parameters under feedback constraints, improving secure communication performance.

Findings

Using 20% of feedback bits for channel gain quantization is effective.

8 feedback bits per antenna achieve about 90% of perfect feedback throughput.

The proposed method outperforms previous solutions assuming perfect feedback.

Abstract

We present an optimized secure multi-antenna transmission approach based on artificial-noise-aided beamforming, with limited feedback from a desired single-antenna receiver. To deal with beamformer quantization errors as well as unknown eavesdropper channel characteristics, our approach is aimed at maximizing throughput under dual performance constraints - a connection outage constraint on the desired communication channel and a secrecy outage constraint to guard against eavesdropping. We propose an adaptive transmission strategy that judiciously selects the wiretap coding parameters, as well as the power allocation between the artificial noise and the information signal. This optimized solution reveals several important differences with respect to solutions designed previously under the assumption of perfect feedback. We also investigate the problem of how to most efficiently utilize the feedback bits. The simulation results indicate that a good design strategy is to use approximately 20% of these bits to quantize the channel gain information, with the remainder to quantize the channel direction, and this allocation is largely insensitive to the secrecy outage constraint imposed. In addition, we find that 8 feedback bits per transmit antenna is sufficient to achieve approximately 90% of the throughput attainable with perfect feedback.