Artificial-Noise-Aided Secure Multi-Antenna Transmission With Limited Feedback
Authors: Xi Zhang, M. R. McKay, Xiangyun Zhou, Robert W. Heath, Jr.
IEEE Transactions on Wireless Communications, vol. 14, no. 5, pp. 2742 - 2754, May 2015
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.